Cannula insertion system

Abstract

The disclosure provides a cannula insertion system to insert a cannula into a blood vessel of a patient, comprising: a cannula insertion device configured to insert the cannula into the patient, a cannula insertion device positioning system to position the cannula insertion device with respect to the patient, and a control device arranged to control the positioning system to position the cannula insertion device in a suitable position to insert the cannula into patient, wherein the cannula insertion system is configured to carry out a blood drawing step, wherein the cannula insertion system comprises a blood flow rate sensor device arranged to determine a blood flow rate of blood being drawn from the patient during the blood drawing step, and wherein the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device and / or a blood collection system and / or an ultrasound transducer positioning system in dependence on the determined blood flow rate of blood being drawn from the patient.

Description

[0001] Title: Cannula insertion system

[0002] The present disclosure relates to a cannula insertion system for inserting a cannula into a body part of a patient.

[0003] WO21140116 A1 discloses a cannula insertion system. The cannula insertion system comprises a cannula insertion device arranged to insert the cannula into a blood vessel of a patient. The cannula insertion system may be used to draw blood from a patient. This blood may be collected in a blood collection tube which blood collection tube is in fluid communication with the cannula. Usually two or more blood collection tubes are filled after each other.

[0004] In an embodiment of the cannula insertion system of WO21140116 A1 , the cannula insertion system may comprise a blood presence sensor located near, on or in the cannula arranged to determine the presence of blood in the cannula. When the presence of blood has been detected in the cannula, a successful penetration of the blood vessel is assumed and filling of the one or more blood collection tubes is started.

[0005] Further, to determine whether a blood collection tube is sufficiently filled a sensor may be provided that is capable of providing a level signal representative for sufficient filling of the blood collection tube. This sensor is for example a level sensor that can measure whether a predetermined level of blood in the blood collection tube has been reached.

[0006] Once it is determined that the blood collection tube is sufficiently filled, blood drawing may be stopped or the cannula may be brought in fluid communication with another blood collection tube for filling of this blood collection tube.

[0007] It is an object of the present disclosure to provide a cannula insertion system with an improved control of drawing of blood using a cannula insertion system, or at least to provide an alternative.

[0008] According to a first aspect of the present disclosure there is provided a cannula insertion system to insert a cannula into a patient, comprising: a cannula insertion device configured to insert the cannula into the patient, a cannula insertion device positioning system to position the cannula insertion device with respect to the patient, and a control device arranged to control the positioning system to position the cannula insertion device in a suitable position to insert the cannula into patient and / or control the cannula insertion device to insert the cannula into the patient, wherein the cannula insertion system is configured to carry out a blood drawing step, wherein the cannula insertion system comprises a blood flow rate sensor device arranged to determine a blood flow rate of blood being drawn from the patient during the blood drawing step, and wherein the control device is configured to control the cannula insertion device positioning system, the cannula insertion device, a blood collection system and / or an ultrasound transducer positioning system in dependence on the determined blood flow rate of blood being drawn from the patient.

[0009] By providing a blood flow rate sensor device, a blood flow rate of blood being drawn from the patient during the blood drawing step may be determined. Such blood flow rate is not determined by the blood presence sensor or the level sensor described in WO21140116 A1. . In prior art devices, it is assumed on the basis of the detection of presence of blood in the cannula, as determined by the blood presence sensor, that there is a substantial blood flow through the cannula. However, the presence of blood in the cannula as determined by the blood presence sensor does not always reliably predict whether the cannula is correctly inserted in the blood vessel such that there is established a substantial blood flow to draw blood from the blood vessel. As a result, blood drawing might take a very long time or not succeed at all.

[0010] The blood flow rate can be used by the control device to control the cannula insertion device positioning system and / or control the cannula insertion device in dependence on the determined blood flow rate of blood being drawn from the patient. When it is determined that the blood flow rate is insufficient, e.g. lower than a desired (minimum) blood flow rate value, different remedial actions may be taken to improve the blood flow rate. For example, the cannula may be inserted further into the patient and / or the cannula may be at least partially retracted from and subsequently reinserted into the patient. If these actions do not result in a larger blood flow rate in the cannula, the cannula may be completely retracted from the patient. In some cases it may be directly decided to completely retract the cannula from the patient (e.g., without attempting any prior remedial actions). In some cases, retraction of the cannula from the patient may be performed when aborting the blood drawing procedure.

[0011] In addition or as an alternative, the blood flow rate as determined by the blood flow rate sensor device can also be used to determine when to switch to a next blood collection tube. For example, when it is determined that the blood draw rate decreases after a period of a substantial blood flow rate, it can be decided a vacuum in the blood collection tube is depleted. The control device may then decide to connect a new blood collection tube.

[0012] In an embodiment, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to maintain the cannula in its position when the blood flow rate is at and / or above a desired or otherwise predetermined blood flow rate value, and to reposition the cannula when the blood flow rate is below the desired blood flow rate value or otherwise predetermined blood flow rate value.

[0013] The desired blood flow rate value may be a desired minimum blood flow rate value or a desired blood flow rate value range at and / or above which the cannula is maintained in its position. Repositioning of the cannula may be carried out when the measured blood flow rate is below the desired (minimum) blood flow rate value or desired (minimum) blood flow rate value range.

[0014] The desired blood flow rate does not have to be a fixed value but may be dependent on different factors. The desired blood flow rate may depend on the patient or characteristics of the patient. For example, the desired blood flow rate may depend on age, weight, body mass index, health state and / or blood pressure. The desired blood flow rate may additionally or alternatively depend on the filling level of a blood collection tube, for example when the inflow of blood into the blood collection tube depends on a pressure level in the blood collection tube. Also other factors, such as cannula size may additionally or alternatively have an influence on the desired blood flow rate value.

[0015] The desired blood flow rate value for a patient may change over time. For example, during the blood drawing process the desired blood flow rate value may decrease over time.

[0016] In an embodiment, when the blood flow rate is below the desired blood flow rate value, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula further into the patient. It has been found that in some cases the blood presence sensor may detect that blood is present in the cannula once the cannula has pierced into the wall of the blood vessel, but before the distal end has completely entered the blood vessel. This may for instance be the case when the blood vessel is pushed away, e.g. in a downwards movement at least partially away from the skin of the patient, instead of penetrating into the cannula. In such a case, it may be beneficial to insert the cannula further into the patient to bring the distal end of the cannula completely into the blood vessel in order to increase the blood flow rate in the cannula.

[0017] The further insertion of the cannula into the blood vessel may be done with a number of subsequent steps (e.g., increments), whereby after each step it is determined on the basis of the measurement of the blood flow rate sensor device whether the blood flow rate value has increased. The steps of further insertion of the cannula into the patient may for example be 0.1 mm to 1.5 mm, for example in the range of 0.2 mm to 0.8 mm. It is also possible to gradually and continuously insert the cannula further into the patient, while monitoring the blood flow rate in the cannula.

[0018] When the blood flow rate value is at least the desired minimum blood flow rate value, further insertion of the cannula may be stopped. When further insertion of the cannula does not result in an increase of the blood flow rate, for example when a certain predetermined distance has been reached, further insertion of the cannula may be stopped.

[0019] In an embodiment, when the blood flow rate is below a desired blood flow rate value, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient. In some cases, when inserting a cannula into a patient, the cannula may push the blood vessel aside, e.g. at least partially perpendicular to the insertion direction of the cannula, instead of penetrating the blood vessel. In this situation, further insertion of the cannula into the patient may not result in penetration of the blood vessel. In such situation it may be beneficial to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient to bring the cannula into the blood vessel. Such retry of inserting the cannula into the blood vessel may lead to the cannula entering the blood vessel. To increase the chance that the cannula will enter the blood vessel the insertion parameters of the cannula may be changed. For example, it may be possible to change the insertion speed of the cannula.

[0020] In an embodiment, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula until only the distal cannula end is in the patient, to rotate the cannula, for example about a rotation point approximately at a penetration location where the cannula penetrates the skin of the patient, to adjust an insertion direction of the cannula, and to subsequently reinsert the cannula into the blood vessel in the adjusted insertion direction. Another insertion parameter that may be changed is the insertion direction with which the cannula is inserted into the patient. For example, when the blood vessel is pushed aside when the cannula is inserted into the patient, the chance that the cannula will enter the blood vessel may increase when the insertion direction is adjusted, for example by directing the cannula in a direction perpendicular to the wall of the blood vessel.

[0021] The insertion direction may be adjusted in different directions, for example the insertion angle of the cannula, e.g., the angle of the cannula with respect to a horizontal plane may be adjusted and / or an angle of the cannula with respect to a vertical plane may be adjusted.

[0022] It may be advantageous to retract the cannula until only the distal cannula end is in the patient and to use a rotation point of the cannula approximately at a penetration location where the cannula penetrates the skin of the patient to adjust the insertion direction to minimize the movement of the cannula within the arm of the patient.

[0023] In an alternative embodiment, the control device may be configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula until the cannula is out of the patient, e.g. to just above the skin, to rotate the cannula to adjust an insertion direction of the cannula, and to subsequently reinsert the cannula into the patient in the adjusted insertion direction.

[0024] In an embodiment, the cannula insertion system comprises a further sensor configured to determine a signal representative of a movement of a blood vessel (e.g., movement resulting from inserting the cannula into the patient), and wherein the control device is further configured to control the cannula insertion device positioning system and / or the cannula insertion device in dependence on the determined signal representative of the movement of the blood vessel resulting from inserting the cannula into the patient.

[0025] The further sensor may, for example, include an ultrasound transducer that is used to obtain an ultrasound image of the blood vessel in the patient. In the ultrasound image a movement, e.g., a change in position, of the blood vessel may be determined. The ultrasound transducer may also be used to determine a position of the cannula with respect to the blood vessel.

[0026] The further sensor may also be any other sensor, such as an infrared sensor or near infrared sensor, to determine a signal representative of a movement of a blood vessel (e.g., resulting from inserting the cannula into the patient).

[0027] As a further alternative, the further sensor may be a force sensor that determines a force exerted on a distal end of the cannula when the cannula is inserted into the body of the patient.

[0028] In dependence on the determined signal representative of the movement of the blood vessel, it may be decided whether the cannula should be inserted further into the patient, for example when the blood vessel is pushed away by the cannula, or the cannula should be at least partially retracted from the patient and reinserted, for example when the blood vessel is pushed away (downwards) and / or pushed aside (sidewards) by the cannula.

[0029] In an embodiment, the cannula is connected to a blood collection tube to receive blood that is drawn from the blood vessel, wherein the blood flow rate sensor device comprises a sensor to measure a quantity of blood in the blood collection tube and a processor to determine a blood flow rate in the cannula from a change in the measured quantity of blood in the blood collection tube. In this embodiment, a sensor that measures a quantity of blood in the blood collection tube may be used to determine the blood flow rate in the cannula, since the time derivative of this quantity of blood in the blood collection tube is representative of the blood flow rate in the cannula.

[0030] The blood flow rate sensor device may comprise a processing device that is configured to determine the blood flow rate in the cannula on the basis of the measured quantity of blood in the blood collection tube.

[0031] The sensor to measure the quantity of blood in the blood collection tube may for example comprise a sensor that is configured to determine a filling level of the blood collection tube, a weight of the blood collection tube and / or a temperature of the blood collection tube. The sensor can, for example, include a capacitive sensor and / or optical sensor.

[0032] In an embodiment, the blood flow rate sensor device comprises a sensor to measure a blood flow rate in the cannula. Any suitable location may be used to provide a sensor to measure a signal representative of the blood flow rate in the cannula. The cannula may have a patient needle to be inserted into a patient. The cannula may be part of a cannula set, the cannula set further comprising a tube needle to be inserted into a blood collection tube and a conduit connecting the patient needle and the tube needle. In such cannula set, the blood flow rate sensor device may also be arranged at another location to measure a blood flow rate in the cannula.

[0033] The sensor may for example be arranged on or in the patient needle that is inserted into the patient, on or in the tube needle that is inserted into the blood collection tube, or on or in the conduit connecting the patient needle and the tube needle. The sensor may also be arranged at a connector hub of one of the patient needle and the tube needle that connects the respective needle with the conduit. The sensor may also be arranged at any other suitable location.

[0034] The blood flow rate sensor device may comprise an optical sensor, a capacitive sensor, a weight sensor, a temperature sensor, an ultrasound sensor, and / or any other suitable sensor that provides a signal that is representative for or can be used to determine the blood flow rate in the cannula.

[0035] The blood flow rate sensor device may comprise a processing device to determine a blood flow rate based on the signal provided by the sensor. The processing device may be a separate processing device or be formed by a central processing device of the cannula insertion system. In addition to the blood flow rate sensor, the cannula insertion system may comprise a blood flow sensor to determine if there is a blood flow through the cannula or not, wherein the blood drawing step starts when the blood flow sensor determines a blood flow through the cannula. Such sensor may not be able to determine the blood flow rate, but only if there is blood flow or not. It is also possible that the blood flow rate sensor device is used to determine the presence of blood in the cannula.

[0036] In an embodiment, the control device is configured to control a blood collection system to switch a blood collection tube connected to the cannula in dependence on the determined blood flow rate of blood being drawn from the patient.

[0037] The blood flow rate as determined by the blood flow rate sensor device can be used to determine when to switch to a next blood collection tube. In some types of blood collection tubes, a vacuum in the blood collection tube is used to draw blood into the blood collection tube. Thus, when it is determined that the blood draw rate decreases after a period of a substantial blood flow rate, it can be decided that vacuum in the blood collection tube is depleted. The control device may then decide to connect a new blood collection tube held by the blood collection system.

[0038] In an embodiment, the blood flow rate profile, i.e. the change of the blood flow rate over time, may be compared with an expected blood flow rate under normal conditions. When the blood flow rate decreases in line with the expected blood flow rate profile, this can be used as an additional indication that a new blood collection tube should be connected to the cannula set.

[0039] Another parameter that may be taken into account is the location of the cannula with respect to the blood vessel.

[0040] In an embodiment, the cannula insertion system comprises a processing device, wherein the processing device is configured to determine a type of puncture failure when there is no blood flow in the cannula or when the blood flow rate in the cannula and / or in a blood collection tube is below a desired blood flow rate value. If after a puncture attempt there is no blood flow in the cannula, for example measured by a blood flow sensor, or when the blood flow rate in the cannula and / or in a blood collection tube is below a desired blood flow rate value, as measured by the blood flow rate sensor device, the type of puncture failure may be determined by a processing device based on information provided by the cannula insertion system. The processing device may be provided integrally with the control device or as a separate device. The control device and the processing device may be provided as a single processor, for example a PC. In an embodiment, the cannula insertion system comprises an ultrasound transducer to obtain an ultrasound image of the patient including at least partially the blood vessel, and wherein the processing device is configured to determine the type of puncture failure on the basis of the ultrasound image. An ultrasound image obtained with an ultrasound transducer may be used to determine a type of puncture failure that occurs. In addition or as an alternative, any other information available in the cannula insertion system, for example data obtained from NIR (near infrared), infrared and / or visible light sensors, may be used to determine the type of puncture failure.

[0041] The determined type of puncture failure can be, for example, that the blood vessel moves aside, e.g. at least partially perpendicular to the insertion direction of the cannula, that the blood vessel moves downwards, e.g. at least partially away from the skin of the patient, and / or that the blood vessel collapses.

[0042] As noted before, the desired blood flow rate does not have to be a fixed value but may be dependent on one or more factors or variables, such as the patient or characteristics of the patient, e.g. age, weight, body mass index, health state and / or blood pressure. The desired blood flow rate may additionally or alternatively depend on the filling level of a blood collection tube. The desired blood flow rate value for a patient may change over time.

[0043] When the determined type of puncture failure is that the blood vessel moves aside, any one or more of a first set of actions can be performed.

[0044] A first action that can be performed is that the control device can be configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient (e.g., without adjusting an insertion direction of the cannula). In this first action, the cannula can be partially be retracted from the patient such that at least the distal end of the cannula remains in the patient, or can be completely retracted from the patient.

[0045] A second action that can be performed is that the control device can be configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient, to rotate the cannula to adjust an insertion direction of the cannula and to subsequently reinsert the cannula into the patient in the adjusted insertion direction. With this second action, the adjusted insertion direction can be selected to improve the chance that the cannula will be inserted into the blood vessel. For example, when the blood vessel moves aside in a direction of movement, the adjusted insertion direction can be selected to insert the cannula to an adjusted insertion location, wherein the adjusted insertion location is shifted in the direction of movement with respect to the insertion location of the previous puncture attempt. The rotation of the cannula may for example be about a rotation point approximately at a penetration location where the cannula penetrates the skin of the patient. The rotation of the cannula may be over any suitable range of angles, for example within the range of 0 to 60 degrees, such as within the range of 0 to 30 degrees.

[0046] As a third action that can be performed, the control device can be configured to control the ultrasound transducer positioning system to adapt a position and / or an orientation of the ultrasound transducer to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient. For example, when the determined type of puncture failure is that the blood vessel moves aside in a direction of movement, the control device may be configured to control the ultrasound transducer positioning system to rotate the ultrasound transducer tangentially with respect to a longitudinal axis of the blood vessel in the direction of movement. As a result of this rotation, the ultrasound transducer will push more at the side of the vessel in which direction the blood vessel moved during a previous puncture attempt. This will reduce the chance that the blood vessel will move to the same extent in the same direction of movement as during the previous attempt.

[0047] The first, second and third actions of the first set of actions can be carried out independently of each other (e.g. a single one of the first set of actions, or multiple actions of the first set of actions performed separately and / or in series), but also in combination.

[0048] When the determined type of puncture failure is that the blood vessel moves downwards, any one or more of a second set of actions can be performed.

[0049] A first action of the second set of actions that can be performed is that the control device can be configured to control the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula further into the patient.

[0050] A second action of the second set of actions is that the control device can be configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient, wherein the insertion depth may the same or larger than the insertion depth of a previous puncture attempt.

[0051] As a third action of the second set of actions, the control device can be configured to control an ultrasound transducer positioning system to increase a force with which the ultrasound transducer is pushed onto the skin of the patient.

[0052] The first, second and third actions of the second set of actions can be carried out independently of each other (e.g. a single one of the second set of actions, or multiple actions of the second set of actions performed separately and in series), but also in combination. For example, the further insertion of the cannula into the patient may be combined with increasing the force with which the ultrasound transducer is pushed onto the skin of the patient When the determined type of puncture failure is that the blood vessel collapses, any one or more of a third set of actions can be performed.

[0053] As a first action of the third set of actions that can be performed, the control device can be configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient.

[0054] A second action that can be performed is that the control device can be configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient, to rotate the cannula to adjust an insertion direction of the cannula to a steeper angle and to subsequently reinsert the cannula into the patient in the adjusted insertion direction with steeper angle. The rotation of the cannula may for example be about a rotation point approximately at a penetration location where the cannula penetrates the skin of the patient. Adjusting the insertion direction of the cannula to a steeper angle results in a smaller angle with respect to a line perpendicular to the skin at the location where the cannula penetrates the skin.

[0055] As a third action that can be performed, the control device can be configured to control a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to increase a clamping pressure on the arm or leg, respectively. The cannula insertion system may comprise a tourniquet device through which an arm or leg of the patient is placed. The tourniquet device is arranged to hold the arm or leg and to exert a clamping pressure on the arm or leg to facilitate insertion of a cannula into the blood vessel. Once a cannula is inserted into the blood vessel, the clamping pressure may be reduced to promote blood flow into the arm or leg. By increasing the clamping pressure the blood pressure in the blood vessel will be increased. This may facilitate the insertion of the cannula into the blood vessel.

[0056] The first, second and third actions of the third set of actions can be carried out independently of each other (e.g. a single one of the third set of actions, or multiple actions of the third set of actions performed separately and in series), but also in combination.

[0057] It is noted that in any of the actions of the first, second or third set of actions in which the cannula was already inserted at least partially into the blood vessel and the cannula is, due to a determined puncture failure, at least partially retracted from the patient, a fluid connection between the cannula and a blood collection tube may be disconnected before retraction of the cannula. Disconnecting the fluid connection between the cannula and a blood collection tube may for example comprise pulling a tube needle out of a blood collection tube, closing a valve in a fluid connection between the cannula and the blood collection tube or by pressing a conduit between the cannula and the blood collection tube closed. The actions of the first, second and third set of actions may, in some applications, be applied together with any other action of the first, second and third set of actions, simultaneously in combination or subsequently, in dependence on the circumstances.

[0058] According to a second aspect of the present disclosure, there is provided a cannula insertion system to insert a cannula into a blood vessel of a patient, comprising: a cannula insertion device configured to insert the cannula into the patient, a cannula insertion device positioning system to position the cannula insertion device, and a control device arranged to control the cannula insertion system and / or the cannula insertion device, wherein the cannula insertion system is arranged to carry out two or more process steps, wherein the cannula insertion system comprises a sensor to measure an actual value of a process step related parameter, wherein the control device is arranged to compare the actual value with a desired value of the process step related parameter, and wherein the control device is arranged to control the cannula insertion system in dependence on the comparison of the actual value and the desired value.

[0059] During a blood drawing process using an automatic cannula insertion system, it may be desirable to monitor an actual value of a process step related parameter. This actual value may be compared with a desired value and action may be taken when the actual value does not correspond to the desired value.

[0060] The desired value (e.g., predetermined value) may be patient specific and / or may be different over time. The desired value may further be a threshold value, e.g., a minimum value or a maximum value, a range or a specific value.

[0061] In an embodiment, the process steps comprise: a localisation step to locate a suitable location for insertion of the cannula, a cannula insertion step to insert a cannula into the blood vessel, and a blood drawing step to draw blood from the patient.

[0062] For each of these steps, different process related parameters may be relevant and therefore different process related parameters may be monitored during different steps of the process. In an embodiment, the sensor is configured to determine during the localisation step: a shape of the blood vessel, a position of the blood vessel within the patient and / or a blood flow or blood flow rate in the blood vessel.

[0063] During the localisation step, the shape of the blood vessel, the position of the blood vessel within the patient and / or a blood flow or blood flow rate in the blood vessel may be relevant for deciding whether the specific blood vessel is suitable for insertion of a cannula into the blood vessel. Other process related parameters may also be relevant during the localisation step.

[0064] In an embodiment, the sensor is configured to determine during the cannula insertion step: a blood flow in the cannula, a position of the cannula with respect to the blood vessel, a shape of the blood vessel, a position of the blood vessel within the patient, a blood flow or blood flow rate in the blood vessel, and / or a force on the cannula.

[0065] During the cannula insertion step, these parameters may be relevant for insertion of the cannula into the blood vessel. In dependence on these parameters, actions can be taken to improve the insertion of the cannula into the blood vessel.

[0066] In an embodiment, the sensor is configured to determine during the blood drawing step: a blood flow or a blood flow rate in the cannula, a position of the cannula with respect to the blood vessel, a shape of the blood vessel, a position of the blood vessel within the patient, a blood flow or blood flow rate in the blood vessel, a quantity of blood or blood flow rate in a blood collection tube, and / or a force on the cannula.

[0067] During the blood drawing step, these parameters may be monitored. In dependence on these parameters actions can be taken to improve the blood drawing from the blood vessel.

[0068] In an embodiment, the control device is configured to control in dependence on the comparison of the actual value and the desired value: the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula into or retract the cannula from the patient (e.g., without changing an insertion direction of the cannula), the cannula insertion device positioning system and / or the cannula insertion device to reposition the cannula, for example retract, rotate and reinsert the cannula, a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, an ultrasound transducer positioning system to adapt a position and / or an orientation of an ultrasound transducer of the cannula insertion system to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, a patient interface to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system.

[0069] In case the actual value of the process related parameter is different than the desired value of the process related parameter one of these actions can be taken to influence the blood drawing process. If such action or series of action does not have the desired result, it may also be decided by the processing or control device to abort the blood drawing process.

[0070] In an embodiment, the cannula insertion system comprises an ultrasound transducer to determine a position and / or cross-section of the blood vessel, and the control device is configured to determine based on the position and / or cross-section of the blood vessel if the blood vessel is a vein or artery, the blood vessel is pushed away, a cannula is penetrated into the blood vessel, the blood vessel is pushed aside and / or the blood vessel has collapsed.

[0071] In an embodiment, the cannula insertion system comprises an infrared sensor to determine a position of the blood vessel with respect to the body, and the control device is configured to determine based on the position of the blood vessel if the blood vessel is a vein or artery, the blood vessel is pushed away, a cannula is penetrated into the blood vessel and / or the blood vessel is pushed aside.

[0072] In an embodiment, when the cannula is placed into the blood vessel and a blood flow rate in the cannula is below a desired blood flow rate value or when the blood vessel is pushed aside, the control device is configured to control: the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula into or retract the cannula from the patient (e.g., without changing an insertion direction of the cannula), the cannula insertion device positioning system and / or the cannula insertion device to reposition the cannula, for example retract, rotate and reinsert the cannula, a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, an ultrasound transducer positioning system to adapt a position and / or an orientation of an ultrasound transducer of the cannula insertion system to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, disconnect a fluid connection between the cannula and a blood collection tube, a patient interface to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system.

[0073] In an embodiment, when the blood vessel has collapsed, the control device is configured to control: the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula into or retract the cannula from the patient (e.g., without changing an insertion direction of the cannula), the cannula insertion device positioning system and / or the cannula insertion device to reposition the cannula, for example retract, rotate and reinsert the cannula, a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, an ultrasound transducer positioning system to adapt a position and / or an orientation of an ultrasound transducer of the cannula insertion system to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, disconnect a fluid connection between the cannula and a blood collection tube, a patient interface to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system.

[0074] Disconnecting the fluid connection between the cannula and a blood collection tube may for example result from pulling a tube needle out of a blood collection tube, closing a valve in a fluid connection between the cannula and the blood collection tube and / or by pressing a conduit between the cannula and the blood collection tube closed.

[0075] In an embodiment, the cannula insertion system comprises a blood flow rate sensor device arranged to determine a blood flow rate of blood being drawn from the patient during the blood drawing step, and wherein the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device in dependence on the determined blood flow rate of blood being drawn from the patient.

[0076] Further characteristics and advantages of the cannula insertion system of the present technology will now be explained by the following description, whereby reference is made to the appended drawings, in which: Figure 1 shows schematically an example embodiment of a cannula insertion system in accordance with the present disclosure;

[0077] Figure 2 shows a situation in which a cannula has pushed a blood vessel away, instead of penetrating the blood vessel V;

[0078] Figure 3 shows a situation in which a cannula has pushed a blood vessel aside, instead of penetrating the blood vessel V;

[0079] Figure 4 shows a situation in which the insertion direction of a cannula has been adjusted to penetrate into the blood vessel V;

[0080] Figure 5 shows a situation in which a blood vessel has collapsed during insertion of a cannula;

[0081] Figure 6 shows the position of an ultrasound transducer in the situation of Figure 3; and

[0082] Figure 7 shows an adjusted position of the ultrasound transducer to prevent or reduce movement of the blood vessel.

[0083] Figure 1 shows schematically a cannula insertion system, generally denoted by reference numeral 1. Further details of the cannula insertion system are for example described in W02021140116, the contents of which are herein incorporated by reference.

[0084] The cannula insertion system 1 is configured to autonomously insert a cannula 2, for example a needle into a blood vessel V of a patient. The patient may be any human or animal that uses the cannula insertion system 1 to insert a cannula into the body of the patient. The cannula insertion system 1 as shown in Figure 1 is in particular configured to autonomously draw blood from a blood vessel. In alternative embodiments, the cannula insertion system 1 may be configured to arrange a cannula in a blood vessel V for other suitable purposes such as intravenous medication and / or infusions.

[0085] To draw blood from the blood vessel V, the cannula insertion system 1 may be arranged to determine a location of a blood vessel underneath the skin S of the patient, insert a cannula 2 into the blood vessel V, and draw blood from the blood vessel V without direct interaction of an operator of the cannula insertion system 1.

[0086] The cannula insertion system 1 may comprise a tourniquet device through which an arm or leg of the patient is placed. The tourniquet device is arranged to hold the arm or leg and to exert a clamping pressure on the arm or leg to facilitate insertion of a cannula into the blood vessel V. Once a cannula is inserted into the blood vessel, the clamping pressure may be reduced to promote blood flow into the arm or leg.

[0087] The cannula insertion system 1 , shown in Figure 1, comprises an ultrasound transducer 3 to obtain one or more sensor signals that are representative for the location of a blood vessel V in the patient. The ultrasound transducer 3 may be a contact sensor. The ultrasound transducer 3 may also referred to as ultrasound probe. During use, contact between the ultrasound transducer 3 and the skin S enables the acquisition of relevant data with respect to the location of the blood vessel V. The ultrasound transducer may be guided along the skin S of the patient in a target area T. This target area T is an area of the skin S underneath which the presence of a blood vessel V suitable for insertion of a cannula 2 is expected and which is examined by the ultrasound transducer 3. A control device 5 controls the position of the ultrasound transducer 3.

[0088] The target area T may be determined by obtaining images of the skin of patient, for example using NIR (near infrared), infrared and / or visible light sensors 15, and determining on the basis of the images an area in which it is likely that a blood vessel suitable for insertion of a cannula will be found. The cannula insertion system 1 has multiple fixed sensors, i.e. sensors mounted at a fixed location, such as sensor 15. These multiple fixed sensors may be used to determine the target area, i.e. an approximate location of a blood vessel that can be used for insertion of the cannula 2. In an alternative embodiment, one or more of these NIR or visible light sensors may be arranged on a movable end-effector 4.

[0089] In addition, or as an alternative the fixed sensors 15 may be used to determine a location of the elbow pit of the arm and / or the shape of the arm. The sensors 15 could also be used to detect areas which should not be used for venipuncture, like birthmarks and wounds.

[0090] Once a target area T is determined, the ultrasound transducer 3 may be used to provide a sensor signal representative for a location of the blood vessel V within the target area T. The sensor signal is fed into a processing device 6 which is arranged to process the sensor signal. The control device 5 and the processing device 6 may be comprised in a single processer 7, such as a PC, or among a distributed network of multiple processors.

[0091] On the basis of the sensor signal provided by the ultrasound transducer 3, an image of the vein may be created by the processing device 6. This image may be based on multiple 2D images along a line in a certain direction, 3D coordinates and direction, 6D coordinates or may be a 3D image.

[0092] The processing device 6 determines on the basis of the sensor signal, or sensor signals, the location of a blood vessel V suitable for the insertion of the cannula 2. On the basis of this location, the processing device 6 may determine an insertion path for insertion of the cannula 2 into the blood vessel V. The processing device 6 may also locate nerves and prevent the cannula 2 from penetrating those nerves, when selecting an insertion path for the cannula 2.

[0093] If no suitable location for insertion of the cannula 2 can be found, the cannula insertion system 1 may request the patient to place the other arm in the cannula insertion system 1 (e.g., by displaying written and / or graphical instructions on a display device or other patient interface, providing audible instructions from a speaker device, etc.).

[0094] The cannula 2 is arranged on a cannula insertion device 8. The cannula 2 is held by a cannula holder 10. The cannula 2 can be taken out of the cannula holder to facilitate exchange of cannulas 2.

[0095] The cannula insertion device 8 is arranged to insert the cannula 2 in an insertion direction ID through the skin S at an insertion location and into the blood vessel V along the insertion path determined by the processing device 6. The cannula insertion device comprises a rotation actuator to adjust an insertion angle of the cannula 2 to align a longitudinal axis of the cannula 2 with the insertion direction ID. A linear actuator is provided to translate the cannula 2 along an insertion path in the insertion direction ID.

[0096] The insertion path of the cannula 2 may be adapted to anatomical structures in the arm of the patient. By adapting the position of the cannula insertion device 8 during insertion of the cannula 2, the cannula 2 may also be moved along a non-linear insertion path.

[0097] The cannula insertion device 8 may be provided with a force sensor with which the axial force exerted on the cannula 2 may be measured. By measuring the axial force exerted on the cannula 2, it can be determined when the wall of a vein is penetrated by the cannula 2. Further, this axial force on the cannula 2 may be compared with a maximum allowable axial force threshold value. Insertion of the cannula 2 may be stopped or at least the insertion speed may be lowered when this axial force exceeds this maximum allowable axial force threshold value.

[0098] The cannula insertion device 8 may comprise a safety device arranged to retract the cannula 2 or to release the cannula 2 from the cannula insertion device 8 when a force exerted on the cannula 2 in a direction perpendicular to the insertion direction ID results in exceeding a respective safety threshold value. The release of the cannula 2 from the cannula insertion device 8 may be a complete release or a release in a limited number of degrees of freedom, for example one or two rotation directions. The safety device may for example allow the cannula to freely rotate in the rotation direction in which a torque is exerted on the cannula when this torque exceeds a safety threshold value in order to follow an inadvertent movement of the patient.

[0099] The cannula insertion device 8 is supported by a positioning system 9, for example a robot arm, that is arranged to bring the cannula insertion device 8 in a position from which the cannula insertion device 8 may move the cannula 2 along the insertion path. The cannula insertion device 8 and the positioning system 9 are controlled by the control device 5.

[0100] In some cases, a vein positioned below the ultrasound transducer 3 may become displaced (e.g., laterally displaced) due to the pressure exerted by the ultrasound transducer 3. This may also be referred to as a ‘rolling vein’. When this occurs, this may be determined at least in part on the basis of the measurements of the ultrasound transducer 3. The cannula insertion system 1 may be configured to control the cannula insertion device 8 to actively follow the movement of the vein. In addition, or as an alternative, a mechanism may be provided to prevent displacement of the vein, for example by arranging two mechanical elements on the skin surface at opposite sides of the vein. Also, it is possible to abort the cannula insertion procedure when displacement of the vein is measured by the ultrasound transducer 3.

[0101] In the embodiment shown in Figure 1, the ultrasound transducer s and the cannula insertion device 8 are mounted on a single end-effector 4. This ensures a fixed spatial relationship between the ultrasound transducer 3 and the cannula insertion device 8. The positioning system 9 is therefore used for positioning of both the ultrasound transducer 3 and the cannula insertion device 8. In an alternative embodiment, the ultrasound transducer 3 may be held in a fixed spatial relationship with the cannula 2, such that the tip of the cannula 2 can be tracked very accurately.

[0102] The cannula insertion system 1 comprises a patient or treatment identification device 20. The patient or treatment identification device 20 is configured to read an identification of the patient. Such identification may for example be an identity card, token or chip, a passport, a hospital identity card, token or chip or a letter with barcode, or an insurance card. The patient or treatment identification device 20 may comprise any suitable reader or scanner to read / scan the information provided by the identification of the patient. The patient or treatment identification device 20 may be connected with a central information system, such as an electronic patient file, a laboratory information system (LIS) or other system and may receive all data required for that patient for carrying out a cannula insertion procedure. After the identity of a patient has been determined, the identity of the patient may be confirmed, for example by providing an audible or readable output to the patient that may be confirmed by the patient.

[0103] The cannula insertion system 1 may comprise an emergency button that can be operated by the operator and / or the patient. When this emergency button is operated, the cannula insertion system will start an abort procedure, in which the cannula insertion process is safely stopped.

[0104] The cannula insertion system 1 may further comprise a patient interface, for example a display device 19 that can be seen by the patient.

[0105] The patient interface can be used to provide instructions to the patient, for example to reposition an arm or other body part, to place a different arm or other body part in the cannula insertion system 1, to provide information with respect to the cannula insertion procedure, such as the remaining time of the procedure, and / or display media, such as a video, that may distract the patient from the procedure. The patient interface may also be used for patient input. For example, the patient may be requested to respond to questions, such as to provide confirmation of the identity of the patient, the use of anticoagulation, etc.

[0106] Similarly, the cannula insertion system 1 may comprise an operator interface, such as a display device or communication device, to provide relevant information with respect to the cannula insertion procedure to the operator. This operator interface may for example provide a sound or visual alarm system to inform the operator that the patient requests help. This operator interface may comprise a digital communication device that sends data to a remote device, e.g., a smart watch or tablet device.

[0107] The cannula 2 comprises a patient needle 71 to be inserted into a patient. The cannula is part of a cannula set, the cannula set further comprising a tube needle 72 to be inserted in a blood collection tube 41 and a conduit 73 connecting the patient needle 71 and the tube needle 72. Hubs may be provided to connect the conduit 73 to the patient needle 72 and the tube needle 73. The cannula 2 is provided as a disposable part. To fill a blood collection tube 41 with blood the tube needle 72 is inserted into the blood collection tube 41 and the patient needle 71 into a blood vessel of the human or animal body. Advantageously, the conduit 73 between the patient needle 71 and the tube needle 72 is relatively short so that a relatively low volume of blood is needed to fill the conduit 73.

[0108] Multiple blood collection tubes 41 are held by a blood collection system 75 which may, for example, be mounted on the positioning system 9. As a result, the blood collection system 75 may move together with the end-effector 4 between different positions, e.g. an operating position and an retracted position, and will stay relatively close to the end-effector 4. The blood collection system 75 may also be arranged at a fixed location or on a separate positioning system.

[0109] The blood collection system 75 comprises a carousel 76 comprising multiple holding locations each arranged to hold a blood collection tube 41 and a tube needle insertion device 77 to insert the tube needle 72 in a blood collection tube 41 aligned with the and pull the tube needle out of the blood collection tube 41 after the blood collection tube 41 has been filled with blood. The carousel 76 is rotatable about an axis of rotation extending in z-direction. By rotation about the axis of rotation a selected one of the holding locations can be aligned with the tube needle insertion device 77 to allow the tube needle 72 to be inserted into the blood collection tube held in the selected one of the holding locations. When the blood collection tube 41 is filled, the tube needle insertion device 77 may retract the tube needle 72 out of the blood collection tube 41 and a new holding location and blood collection tube 41 held therein may be aligned with the tube needle insertion device 76 by rotation of the carousel 76. When arranged in this position the tube needle insertion device 76 may insert the tube needle 72 into this new blood collection tube 41. The cannula insertion system 1 comprises a blood flow rate sensor device 80 arranged to determine a blood flow rate of blood being drawn from the patient during a blood drawing step.

[0110] The blood flow rate sensor device 80 comprises a filling level sensor configured to determine a filling level of the blood collection tube. This signal representative for the filling level cannot only be used to determine whether the blood collection tube is sufficiently filled, but can also be used to determine the blood flow rate in the cannula 2, since the time derivative of the filling is representative for this blood flow rate. A processing device, for example the processing device 6 or a separate processing device, may be used to calculate the blood flow rate in the cannula 2 based on the signal provided by the filling level sensor.

[0111] In addition, or as an alternative, any other sensor that can be used to determine the blood flow rate in the cannula 2 may also be used. For example, a blood flow rate sensor device 81 may be provided to measure the blood flow rate in the conduit 73. The blood flow rate sensor device 81 may be an optical sensor, a capacitive sensor, a weight sensor, a temperature sensor, an ultrasound transducer, or any other type of sensor that provides a signal representative for the blood flow rate in the cannula 2.

[0112] During the step of drawing blood from a patient, it may be desirable that the actual blood flow rate value as measured by the blood flow rate sensor device 80 and / or the blood flow rate sensor device 81 is at and / or above a desired blood flow rate value, for example at or above a desired minimum blood flow rate value. If the blood actual flow rate value is too low this may, for example, indicate that the cannula 2 is not or no longer properly arranged in the blood vessel of the patient. It may also happen that the blood vessel V has collapsed due to the relative low pressure in the interior of the blood collection tube 41 that is connected to the cannula 2 via the tube needle 72 and the conduit 73.

[0113] The desired (minimum) blood flow rate value may vary in dependence on specific circumstances. For example, the desired blood flow rate value may be different for different patients or patient characteristics, such as age, length, body weight, body mass index, health state and / or blood pressure. The desired blood flow rate value may also vary in dependence on the actual filling level of or pressure level in a blood collection tube 41.

[0114] In some embodiments, as long as the actual blood flow rate value is at or above the desired minimum blood flow rate value, the cannula 2 may be maintained in its position with respect to the blood vessel V to draw blood from the patient. When the actual blood flow rate value is below the desired blood flow rate value, the control device 5 may control the positioning system 9 and / or the cannula insertion device to reposition the cannula. This repositioning may comprise further insertion of the cannula 2 into the patient, or retraction and subsequent reinsertion of the cannula 2 into the patient. Between retraction and reinsertion it may be desirable to adjust the insertion direction ID of the cannula 2. In dependence on the situation one or more of these actions may be carried out.

[0115] When the cannula 2 is retracted from the blood vessel V, it may be desirable to disconnect the fluid connection between the patient needle 71 and the blood collection tube 41, for example by pulling the tube needle 72 out of the blood collection tube 41 , closing a valve in the cannula 2 or by pressing the conduit 73 closed in the connection between patient needle 71 and the blood collection tube 41. By disconnection of this fluid connection, it is prevented that the low pressure (vacuum) in the blood collection tube 41 will inadvertently be used to suck in fluid (gas or liquid) when the cannula 2 is no longer placed in the blood vessel V.

[0116] To decide how to reposition the cannula 2 may depend on the reason that the needle is not correctly placed in the blood vessel V.

[0117] Figure 2 shows a first situation in which the blood vessel V is pushed away (e.g., deeper, generally in the same direction as the insertion direction ID) by the cannula 2 instead of the cannula 2 penetrating through the wall of the blood vessel V. The dashed lines show a cross section of the blood vessel V before the cannula 2 is inserted into the patient. In the inserted position of the cannula 2, the distal end is only partly pierced into the wall of the blood vessel V and the blood vessel V has moved away from the cannula 2. As a result, the cannula 2 is not placed in the desired location with respect to the cannula 2. Even though a blood presence sensor may detect that blood is present in the cannula 2, the actual blood flow rate in the cannula 2 is likely to be smaller than the desired blood flow rate value.

[0118] In this case, it may be beneficial to insert the cannula 2 further into the patient to bring the distal end of the cannula 2 completely into the blood vessel V in order to increase the blood flow rate through the cannula 2 to above the desired blood flow rate value.

[0119] The control device 5 may control the cannula insertion device to insert the cannula 2 further into the patient. The further insertion of the cannula 2 into the blood vessel may be done with a number of subsequent steps, whereby at least after each step it is determined on the basis of the measurement of the blood flow rate sensor device whether the blood flow rate has increased. The steps of further insertion of the cannula 2 into the patient may for example be 0.1 mm to 1.5 mm, for example in the range of 0.2 mm to 0.8 mm. It is also possible to gradually and continuously insert the cannula 2 further into the patient, while monitoring the blood flow rate in the cannula.

[0120] When blood flow rate has at least the desired (minimum) blood flow rate value, further insertion of the cannula may be stopped. When further insertion of the cannula does not result in an increase of the blood flow rate, for example after a certain predetermined distance has been reached, further insertion of the cannula 2 may be stopped. Figure 3 shows a second situation, where the blood flow rate may be below a desired blood flow rate value. In this case inserting of the cannula 2 into a patient has resulted in pushing the blood vessel V aside (e.g., in a direction different than the insertion direction ID) instead of penetrating through the wall of the blood vessel V.

[0121] In this situation, further insertion of the cannula 2 in the same insertion direction ID is not likely to improve the chance that the cannula 2 will successfully enter the interior of the blood vessel V. The control device 5 may control the cannula insertion device 8 to retract the cannula 2 at least partially from the blood vessel V and to subsequently reinsert the cannula 2 into the blood vessel V. By retraction of the cannula 2, the blood vessel V may move back to its original position as shown by dashed lines. Reinsertion of the cannula 2 may now have the effect that the wall of the blood vessel V is successfully penetrated to allow blood to be drawn from the blood vessel V. To increase the chance that the cannula 2 will enter the blood vessel V the insertion parameters, such as insertion speed, of the cannula 2 may be changed.

[0122] In an additional or alternative action the chance on a successful insertion of the cannula 2 into the blood vessel V may be increased by controlling the positioning system 9 to rotate the cannula 2 after retraction to adjust an insertion direction of the cannula, and to subsequently reinsert the cannula 2 into the blood vessel V in the adjusted insertion direction, as shown in Figure 4 (dashed lines indicate the original insertion direction of the cannula 2 and solid lines indicate the adjusted insertion direction of the cannula 2). This adjustment of the insertion direction between retraction and reinsertion may for example be applied when retraction and reinsertion is not successful or expected not to be successful. In an alternative embodiment, possibly dependent on circumstances, the cannula insertion system may directly apply adjustment of the insertion direction between retraction and reinsertion of the cannula 2. The processing device may be configured to decide which action or actions should be taken.

[0123] The insertion direction may be adjusted in different directions, for example the insertion angle of the cannula 2, i.e. the angle of the cannula 2 with respect to a horizontal plane may be adjusted and / or an angle of the cannula 2 with respect to a vertical plane may be adjusted.

[0124] It is advantageous to retract the cannula 2 until only the distal cannula end, i.e. the distal end of the patient needle 71 , is in the patient and to use a rotation point of the cannula approximately at a penetration location where the cannula 2 penetrates the skin of the patient to adjust the insertion direction to minimize the movement of the cannula within the arm of the patient.

[0125] When it is determined that the actual blood flow rate value is smaller than the desired blood flow rate value, the above described actions may be carried out subsequently. For example, the control device 5 may be configured to control the cannula insertion device 8 to first insert the cannula 2 further into the patient (without adjusting insertion angle of the cannula 2). If this does not lead to an actual blood flow rate value above the desired blood flow rate value, the control device 5 may be configured to control the cannula insertion device 8 partially retract and reinsert the cannula 2. If one or more attempts of retraction and subsequent insertion also do not lead to an actual blood flow rate value at and / or above the desired blood flow rate value, the control device 5 may control the cannula insertion device 8 cannula 2 to partially retract the cannula, adjust the insertion direction and reinsert the cannula 2. Any other suitable order of actions may also be applied.

[0126] To improve the efficiency of this process, the decision on the action to be taken may depend on further information, for example a signal representative for a movement of a blood vessel resulting from inserting the cannula into the patient. The signal representative for a movement of a blood vessel may for example be obtained by the ultrasound transducer 3 that provides images of the cross section of the blood vessel V. On the basis of the images the location of the blood vessel V before and after insertion of the cannula 2, or on the basis of an ultrasound image showing the actual location of the cannula 2 and the cross section of the blood vessel, it may be determined whether further insertion or retraction and reinsertion is expected to be more promising for successful insertion of the needle into the blood vessel V.

[0127] In addition or as an alternative an infrared sensor or a near infrared sensor may be used to obtain a signal representative for a movement of a blood vessel resulting from inserting the cannula into the patient

[0128] As another addition or alternative, a force sensor that determines a force exerted on a distal end of the cannula 2 when the cannula 2 is inserted into the body of the patient may be used as a signal representative for a movement of a blood vessel resulting from inserting the cannula into the patient.

[0129] The blood flow rate as determined by the blood flow rate sensor device 80 can also be used to determine when to switch to a next blood collection tube 41. In some types of blood collection tubes, a vacuum in the blood collection tube is used to draw blood into the blood collection tube. Thus, when it is determined that the blood draw rate decreases after a period of a substantial blood flow rate, it can be decided that vacuum in the blood collection tube is depleted. The control device may then decide to connect a new blood collection tube, for example a next blood collection tube 41 in the carousel 76 of the blood collection system 75.

[0130] To further distinguish the decrease of a blood flow rate due to a depleted vacuum in the blood collection tube 41 from another situation other parameters may be taken into account. For example, in an embodiment, the blood flow rate profile, i.e. the change of the blood flow rate over time, may be compared with an expected blood flow rate under normal conditions. When the blood flow rate decreases in line with the expected blood flow rate profile, this can be used as an additional indication that a new blood collection tube should be connected to the cannula set. Another parameter that may be taken into account is the location of the cannula with respect to the blood vessel. When it is determined that the cannula is still properly placed in the blood vessel, for example based on images obtained by the ultrasound transducer 3, but at the same time the blood flow rate substantially decreases this may be a further indication that the vacuum in the blood collection tube 41 is depleted and that a new blood collection tube 41 can be connected to the cannula set.

[0131] It will be clear that when the last blood collection tube 41 to be filled is connected to the cannula set and the blood draw rate decreases after a period of a substantial blood flow rate, the blood drawing process may be stopped instead of connecting a new blood collection tube 41.

[0132] Another parameter that may be relevant for deciding to switch to a new blood collection tube 41 may be the quantity of blood that is already present in the blood collection tube 41. This may for example be determined by a quantity sensor measuring a blood quantity in the blood collection tube 41 or by integrating the measured blood flow rate in the cannula 2.

[0133] The cannula insertion system 1 may comprise a processing device, for example processing device 6, configured to determine a type of puncture failure when there is no blood flow in the cannula or when the blood flow rate in the cannula and / or in a blood collection tube is below a desired blood flow rate value. The type of puncture failure may for example be determined by the processing device 6 on the basis of an ultrasound image of the patient including at least partially the blood vessel V, which ultrasound image is obtained with the ultrasound transducer 3. The determined type of puncture failure is for example that the blood vessel V moves aside ( e.g., at least partially perpendicular to the insertion direction of the cannula, as shown in Figure 3), that the blood vessel moves downwards (e.g. at least partially away from the skin of the patient, as shown in Figure 2) or that the blood vessel V collapses (as shown in Figure 5). The puncture failure may also comprise a combination of two or three of these three types of puncture failures.

[0134] When the determined type of puncture failure includes that the blood vessel V moves aside, the control device 5 may be configured to control the cannula insertion device positioning system 4 and / or the cannula insertion device 10 to retract the cannula 2 at least partially from the patient and to subsequently reinsert the cannula 2 into the patient. Between retraction of the cannula 2 and reinsertion of the cannula 2 into the patient the cannula 2 may be rotated by the cannula insertion device positioning system 4 to adjust an insertion direction of the cannula. After rotation the cannula 2 may be inserted in the adjusted insertion direction as shown in Figure 4. With this adjusted insertion direction the chance that the cannula 2 will be inserted into the blood vessel V will for example be improved as the adjusted insertion direction can be selected to insert the cannula to an adjusted insertion location, wherein the adjusted insertion location is shifted in the direction of movement of the blood vessel during the first attempt.

[0135] In addition or as an alternative, the control device 5 can be configured to control the ultrasound transducer positioning system 9 to adapt a position and / or an orientation of the ultrasound transducer 3 to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer 3 on the skin of the patient.

[0136] Figure 6 shows a puncture failure in which the blood vessel V is moved aside in a direction of movement DM, corresponding to the situation of Figure 3. The ultrasound transducer 3 is shown on top of the skin S. To improve the chance of correct insertion of the cannula 2 into the blood vessel V, the control device 5 may be configured to control the ultrasound transducer positioning system 9 to rotate the ultrasound transducer tangentially with respect to a longitudinal axis of the blood vessel V in a direction of rotation R corresponding to the direction of movement DM of the blood vessel V during a previous puncture attempt.

[0137] Figure 7 shows the ultrasound transducer 3 after rotation in the direction of rotation R. As a result of this rotation the ultrasound transducer 3 will now push more at the side of the blood vessel V in which direction the blood vessel V moved during a previous puncture attempt. This repositioned ultrasound transducer 3 will reduce the chance that the blood vessel V will move to the same extent in the same direction of movement DM as in the previous puncture attempt.

[0138] If the puncture failure is that the blood vessel V moves downwards, as shown in Figure 2, the control device 5 may be configured to control the ultrasound transducer positioning system 9 to increase a force with which the ultrasound transducer 3 is pushed onto the skin S of the patient. By increasing the force exerted with the ultrasound transducer 3 on the skin S of the patient, the distance between the skin S and the blood vessel V may be decreased and the tissue surrounding the blood vessel V may be compressed. As a result, the chance that the cannula 2 is successfully inserted into the blood vessel V is substantially increased.

[0139] This increased force with which the ultrasound transducer 3 is pushed onto the skin S of the patient, may be applied in combination with further insertion of the cannula 2 into the patient or in combination with at least partial retraction of the cannula 2 from the patient and subsequent reinsertion of the cannula 2 into the patient. The force of the ultrasound transducer 3 may for example be increased after partial retraction and before subsequent reinsertion of the cannula 2 into the patient. When the cannula 2 is retracted and subsequently reinserted, the insertion depth may be the same or larger than the original insertion depth of the previous puncture attempt. When the determined type of puncture failure includes that the blood vessel V collapses, as shown in Figure 5, the control device 5 may be configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient. Between retraction and reinsertion, the cannula 2 may be rotated to adjust an insertion direction of the cannula to a steeper angle with respect to the skin S of the patient. Increasing the angle of the cannula with respect to the skin S to a steeper angle may increase the chance that the cannula 2 is successfully inserted into the blood vessel V.

[0140] In addition or as an alternative, the control device 5 may be configured to control the tourniquet device of the cannula insertion system 1 to increase a clamping pressure on the arm or leg exerted by the tourniquet device. The increased clamping pressure may increase the blood pressure in the blood vessel V which will facilitate the insertion of the cannula 2 into the blood vessel V.

[0141] The above described monitoring of the actual blood flow rate and comparing this actual blood flow rate with a desired blood flow rate value in order to decide whether an action is required to improve the blood drawing process is an example of monitoring a process step related parameter and taking subsequent action when needed. In the cannula insertion system 1 shown in Figure 1 also other process step related parameters may be monitored and used to decide whether action should be taken by the control device 5 to improve the blood drawing process.

[0142] Generally, at least three main process steps can be distinguished in the blood drawing process. These main process steps comprise a localisation step to locate a suitable location for insertion of the cannula, a cannula insertion step to insert a cannula into the blood vessel, and a blood drawing step to draw blood from the patient. During each of these process steps one or more actual process related parameter values may be monitored and action can be taken by the control device 5 or another control device when the actual process related parameter value does not correspond with the desired process related parameter value.

[0143] A sensor, for example one of the sensors described hereinabove may be used to measure the actual process related parameter value. The desired process related parameter value may be a specific value, a minimum value or maximum value or a value range. The desired process related parameter value may also be patient specific and be different during different moments in the blood drawing process.

[0144] During the localisation step, one or more of the following process step related parameters may be monitored: a shape of the blood vessel, a position of the blood vessel within the patient and / or a blood flow or blood flow rate in the blood vessel. These process step related parameters may for example be determined on a signal obtained with an infrared, near infrared or ultrasound sensor. A processing device, for example the processing device 6 may be used to process the measured signal to determine the process step related parameter.

[0145] During the cannula insertion step, one or more of the following process step related parameters may be monitored: a blood flow in the cannula, a position of the cannula with respect to the blood vessel, a shape of the blood vessel, a position of the blood vessel within the patient, a blood flow or blood flow rate in the blood vessel, and / or a force on the cannula.

[0146] During the blood drawing step, one or more of the following process step related parameters may be monitored: a blood flow or a blood flow rate in the cannula, a position of the cannula with respect to the blood vessel, a shape of the blood vessel, a position of the blood vessel within the patient, a blood flow or blood flow rate in the blood vessel, a quantity of blood or blood flow rate in a blood collection tube, and / or a force on the cannula.

[0147] The control device 5 is configured to control in dependence on the comparison of the actual value and the desired value of the process related parameter to take an action. These action may include: the positioning system 9 and / or the cannula insertion device 8 to insert the cannula 2 further into or retract the cannula 2 from the patient, the positioning system 9 and / or the cannula insertion device 8 to reposition the cannula 2, for example to retract the cannula 2, rotate the cannula 2 to an adjusted insertion direction and reinsert the cannula 2, a tourniquet device of the cannula insertion system 1 through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, respectively, the positioning system 9 to adapt a position and / or an orientation of an ultrasound transducer 3 of the cannula insertion system 1 to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, disconnect a fluid connection between the cannula and a blood collection tube, the patient interface 19 to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system 1.

[0148] The ultrasound transducer 3 may be configured to determine a position and / or crosssection of the blood vessel V. On the basis of the position and / or cross section of the blood vessel V, it may be determined whether the blood vessel V is a vein or artery, the blood vessel V is pushed away by the cannula 2, a cannula is penetrated into the blood vessel, the blood vessel is pushed aside by the cannula 2 and / or the blood vessel has collapsed.

[0149] When it is determined on the basis of the ultrasound image obtained by the signal of the ultrasound transducer that the cannula 2 is penetrated into the blood vessel V and an actual blood flow rate in the cannula is below a desired blood flow rate value or when the blood vessel is pushed aside, the control device may be configured to control: the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula into or retract the cannula from the patient, the cannula insertion device positioning system and / or the cannula insertion device to reposition the cannula, for example retract, rotate and reinsert the cannula, a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, an ultrasound transducer positioning system to adapt a position and / or an orientation of an ultrasound transducer of the cannula insertion system to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, disconnect a fluid connection between the cannula and a blood collection tube, a patient interface to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system.

[0150] When it is determined on the basis of the ultrasound image obtained by the signal of the ultrasound transducer that the blood vessel has collapsed, the control device may be configured to control: the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula into or retract the cannula from the patient, the cannula insertion device positioning system and / or the cannula insertion device to reposition the cannula, for example retract, rotate and reinsert the cannula, a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, an ultrasound transducer positioning system to adapt a position and / or an orientation of an ultrasound transducer of the cannula insertion system to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, disconnect a fluid connection between the cannula and a blood collection tube, a patient interface to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system.

Claims

CLAIMS1. A cannula insertion system to insert a cannula into a blood vessel of a patient, comprising: a cannula insertion device configured to insert the cannula into the patient, a cannula insertion device positioning system to position the cannula insertion device with respect to the patient, and a control device arranged to control the positioning system to position the cannula insertion device in a suitable position to insert the cannula into patient and / or control the cannula insertion device to insert the cannula into the patient, wherein the cannula insertion system is configured to carry out a blood drawing step, wherein the cannula insertion system comprises a blood flow rate sensor device arranged to determine a blood flow rate of blood being drawn from the patient during the blood drawing step, and wherein the control device is configured to control the cannula insertion device positioning system, the cannula insertion device, a blood collection system and / or an ultrasound transducer positioning system in dependence on the determined blood flow rate of blood being drawn from the patient.

2. Cannula insertion system according to claim 1, wherein the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to: maintain the cannula in its position when the blood flow rate is at and / or above a desired blood flow rate value, and reposition the cannula when the blood flow rate is below the desired blood flow rate value.

3. Cannula insertion system according to claim 2, wherein, when the blood flow rate is below the desired blood flow rate value, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula further into the patient.

4. Cannula insertion system according to claim 2, wherein, when the blood flow rate is below a desired blood flow rate value, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient.

5. Cannula insertion system according to claim 4, wherein the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula until only the distal cannula end is in the patient, to rotate the cannula to adjust an insertion direction of the cannula, and to subsequently reinsert the cannula into the patient along the adjusted insertion direction.

6. Cannula insertion system according to any of the claims 1-5, wherein the cannula is connected to a blood collection tube to receive blood that is drawn from the blood vessel, wherein the blood flow rate sensor device comprises a sensor to measure a quantity of blood in the blood collection tube and a processor to determine a blood flow rate from a change in the measured quantity of blood in the blood collection tube.

7. Cannula insertion system according to claim 6, wherein the sensor to measure a quantity of blood in the blood collection tube comprises a sensor that is configured to determine a filling level of the blood collection tube, a weight of the blood collection tube and / or a temperature of the blood collection tube.

8. Cannula insertion system according to any of the claims 1-7, wherein the blood flow rate sensor device comprises a sensor to measure a blood flow rate in the cannula and / or a tube connected to the cannula.

9. Cannula insertion system according to any of the claims 1-8, wherein the blood flow rate sensor device comprises an optical sensor, a capacitive sensor, a weight sensor, a temperature sensor, and / or an ultrasound sensor.

10. Cannula insertion system according to any of the claims 1-9, wherein the cannula insertion system comprises a blood flow sensor to determine if there is a blood flow through the cannula or not, wherein the blood drawing step starts when the blood flow sensor determines a blood flow through the cannula.

11. Cannula insertion system according to any of the preceding claims, wherein the control device is configured to control a blood collection system to switch a blood collection tube connected to the cannula in dependence on the determined blood flow rate of blood being drawn from the patient.

12. Cannula insertion system according to any of the preceding claims, wherein the cannula insertion system comprises a processing device, wherein the processing device is configured, when there is no blood flow in the cannula or when the blood flow rate in the cannula and / or in a blood collection tube is below a desired blood flow rate value, to determine a type of puncture failure.

13. Cannula insertion system according to claim 12, wherein the cannula insertion system comprises an ultrasound transducer to obtain an ultrasound image of the patient including at least partially the blood vessel, and wherein the processing device is configured to determine the type of puncture failure on the basis of the ultrasound image.

14. Cannula insertion system according to claim 12 or 13, wherein the determined type of puncture failure is selected from:- the blood vessel moves aside;- the blood vessel moves downwards; and / or- the blood vessel collapses.

15. Cannula insertion system according to claim 14, wherein, when the determined type of puncture failure is that the blood vessel moves aside, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient, to rotate the cannula to adjust an insertion direction of the cannula and to subsequently reinsert the cannula into the patient in the adjusted insertion direction, and / or the control device is configured to control an ultrasound transducer positioning system to adapt a position and / or an orientation of the ultrasound transducer to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient.

16. Cannula insertion system according to claim 15, wherein, when the determined type of puncture failure is that the blood vessel moves aside in a direction of movement, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient, to rotate the cannula and to subsequently reinsert the cannula into the patient in the adjusted insertion direction to an adjusted insertion location, wherein the adjusted insertion location is shifted inthe direction of movement with respect to the insertion location of a previous puncture attempt.

17. Cannula insertion system according to claim 15 or 16, wherein, when the determined type of puncture failure is that the blood vessel moves aside in a direction of movement, the control device is configured to control the ultrasound transducer positioning system to rotate the ultrasound transducer tangentially with respect to a longitudinal axis of the blood vessel in the direction of movement.

18. Cannula insertion system according to any of the claims 14-17, wherein, when the determined type of puncture failure is that the blood vessel moves downwards, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula further into the patient, or the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient, wherein the insertion depth may the same or larger than the original insertion depth, and / or the control device is configured to control an ultrasound transducer positioning system to increase a force with which the ultrasound transducer is pushed onto the skin of the patient.

19. Cannula insertion system according to any of the claims 14-18, wherein, when the determined type of puncture failure is that the blood vessel collapses, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient and to subsequently reinsert the cannula into the patient, wherein the insertion depth may the same or larger than the original insertion depth, and / or the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the patient, to rotate the cannula to adjust an insertion direction of the cannula to a steeper angle and to subsequently reinsert the cannula into the patient in the adjusted insertion direction with the steeper angle, and / or the control device is configured to control a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to increase a clamping pressure on the arm or leg, respectively.

20. A cannula insertion system to insert a cannula into a blood vessel of a patient, comprising: a cannula insertion device configured to insert the cannula into the patient, a cannula insertion device positioning system to position the cannula insertion device, and a control device arranged to control the cannula insertion system and / or the cannula insertion device, wherein the cannula insertion system is arranged to carry out two or more process steps, wherein the cannula insertion system comprises a sensor to measure an actual value of a process step related parameter, wherein the control device is arranged to compare the actual value with a desired value of the process step related parameter, and wherein the control device is arranged to control the cannula insertion system in dependence on the comparison of the actual value and the desired value.

21. Cannula insertion system according to any of the preceding claims, wherein the process steps comprise: a localisation step to locate a suitable location for insertion of the cannula, a cannula insertion step to insert a cannula into the blood vessel, and a blood drawing step to draw blood from the patient.

22. Cannula insertion system according to claim 21 , wherein the sensor is configured to determine during the localisation step: a shape of the blood vessel, a position of the blood vessel within the patient and / or a blood flow or blood flow rate in the blood vessel.

23. Cannula insertion system according to claim 21 or 22, wherein the sensor is configured to determine during the cannula insertion step: a blood flow in the cannula, a position of the cannula with respect to the blood vessel, a shape of the blood vessel, a position of the blood vessel within the patient, a blood flow or blood flow rate in the blood vessel, and / or a force on the cannula.

24. Cannula insertion system according to any of the claims 21-23, wherein the sensor is configured to determine during the blood drawing step: a blood flow or a blood flow rate in the cannula, a position of the cannula with respect to the blood vessel, a shape of the blood vessel, a position of the blood vessel within the patient, a blood flow or blood flow rate in theblood vessel, a quantity of blood or blood flow rate in a blood collection tube, and / or a force on the cannula.

25. Cannula insertion system according to any of the claims 20-24, wherein the control device is configured to control in dependence on the comparison of the actual value and the desired value: the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula into or retract the cannula from the patient, the cannula insertion device positioning system and / or the cannula insertion device to reposition the cannula, for example retract, rotate and reinsert the cannula, a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, an ultrasound transducer positioning system to adapt a position and / or an orientation of an ultrasound transducer of the cannula insertion system to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, disconnect a fluid connection between the cannula and a blood collection tube, a patient interface to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system.26 Cannula insertion system according to any of the claims 20-25, wherein the cannula insertion system comprises an ultrasound transducer to determine a position and / or cross-section of the blood vessel, and wherein the control device is configured to determine based on the position and / or cross-section of the blood vessel if the blood vessel is a vein or artery, the blood vessel is pushed away, a cannula is penetrated into the blood vessel, the blood vessel is pushed aside and / or the blood vessel has collapsed.

27. Cannula insertion system according to claim 26, wherein, when the cannula is penetrated into the blood vessel and a blood flow rate in the cannula is below a desired blood flow rate value or when the blood vessel is pushed aside, the control device is configured to control: the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula into or retract the cannula from the patient, the cannula insertion device positioning system and / or the cannula insertion device to reposition the cannula, for example retract, rotate and reinsert the cannula,a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, an ultrasound transducer positioning system to adapt a position and / or an orientation of an ultrasound transducer of the cannula insertion system to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, disconnect a fluid connection between the cannula and a blood collection tube, a patient interface to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system.

28. Cannula insertion system according to claim 26 or 27, wherein, when the blood vessel has collapsed, the control device is configured to control: the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula into or retract the cannula from the patient, the cannula insertion device positioning system and / or the cannula insertion device to reposition the cannula, for example retract, rotate and reinsert the cannula, a tourniquet device of the cannula insertion system through which an arm or leg of the patient is placed to adapt the clamping pressure on the arm or leg, an ultrasound transducer positioning system to adapt a position and / or an orientation of an ultrasound transducer of the cannula insertion system to adjust a magnitude and / or orientation of a force exerted by the ultrasound transducer on the patient, disconnect a fluid connection between the cannula and a blood collection tube, a patient interface to provide instructions to the patient, and / or a body part support positioning system to adapt a position and / or an orientation of a body support part, such as an arm support, hand grip or seat, of the cannula insertion system.

29. Cannula insertion system according to any of the claims 20-28, wherein the cannula insertion system comprises a blood flow rate sensor device arranged to determine a blood flow rate of blood being drawn from the patient during the blood drawing step, and wherein the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device in dependence on the determined blood flow rate of blood being drawn from the patient.

30. Cannula insertion system according to claim 29, wherein the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to:remain the cannula in its position when the blood flow rate is above at and / or above a desired blood flow rate value, and reposition the cannula when the blood flow rate is below the desired blood flow rate value.

31. Cannula insertion system according to claim 30, wherein, when the blood flow rate is below the desired blood flow rate value, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to insert the cannula further into the patient.

32. Cannula insertion system according to claim 30, wherein, when the blood flow rate is below the desired blood flow rate value, the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula at least partially from the blood vessel and to subsequently reinsert the cannula into the patient.

33. Cannula insertion system according to claim 32, wherein the control device is configured to control the cannula insertion device positioning system and / or the cannula insertion device to retract the cannula until only the distal cannula end is in the patient, to rotate the cannula about a rotation point approximately at a penetration location where the cannula penetrates the skin of the patient to adjust an insertion direction of the cannula, and to subsequently reinsert the cannula into the blood vessel in the adjusted insertion direction.

34. Cannula insertion system according to any of the claims 29-33, wherein the cannula is connected to a blood collection tube to receive blood that is drawn from the blood vessel, wherein the blood flow rate sensor device comprises a sensor to measure a quantity of blood in the blood collection tube, and a processor to determine a blood flow rate from a change in the measured quantity of blood in the blood collection tube.

35. Cannula insertion system according to any of the claims 29-34, wherein the cannula insertion system comprises a blood flow sensor to determine if there is a blood flow through the cannula or not, wherein the blood drawing step starts when the blood flow sensor determines a blood flow through the cannula.

Images