System for controlling blood oxygenation

Abstract

A system 100 for controlling blood oxygenation in a patient includes an oxygenator 200 configured to receive blood from a patient and expose the blood to a quantity of oxygen as the blood passes through the oxygenator 200 to produce oxygenated blood. The system 100 further includes a sensor 110 disposed downstream of the oxygenator 200 and configured to measure the oxygen saturation present in the oxygenated blood. The system 100 also includes a controller 150 configured to receive the measured oxygen saturation from the sensor 110, calculate a difference between a target oxygen saturation and the measured oxygen saturation, and adjust the amount of oxygen the blood is exposed to within the oxygenator 200 to reduce the difference.

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to systems and methods for controlling the blood oxygenation of a patient. In particular, the present disclosure relates to systems and methods for more accurately and safely controlling the oxygen saturation in a patient's blood. [Background technology]

[0002] Cardiac perfusion involves the extracorporeal oxygenation of a patient's blood when the patient is unable to oxygenate their own blood by breathing, for example. Extracorporeal oxygenation involves an artificial lung functioning in place of the patient's own lungs, for example during cardiac and / or pulmonary surgery.

[0003] An example of a physiological parameter related to blood oxygenation is blood oxygen saturation, which refers to the percentage of oxygenated hemoglobin relative to the total hemoglobin in a patient's blood. During extracorporeal perfusion, an oxygenator exposes blood to a constant amount of oxygen as it passes through the oxygenator. If this amount of oxygen remains constant, fluctuations in the patient's metabolic rate can lead to fluctuations in blood oxygen saturation. For example, a patient may experience a low metabolic rate. A patient's metabolic rate may be intentionally reduced (e.g., by lowering the patient's body temperature) before placing the patient in circulatory arrest, for example, to perform cardiac surgery. Although the patient's body consumes less oxygen, the oxygenator continues to supply a constant amount of oxygen to the blood. This leads to an increase in oxygen saturation, increasing the risk of hyperoxygenation (i.e., hyperoxia).

[0004] Traditionally, when controlling blood oxygenation, clinicians may directly measure various physiological parameters, such as the partial pressure of oxygen (abbreviated as "PaO2") in a patient's arterial blood. Clinicians may then treat some or all of the physiological parameters (e.g., the partial pressure of oxygen) as "surrogate indicators" of the patient's blood oxygen saturation. That is, clinicians typically rely on the change in and / or absolute value of the partial pressure of oxygen as an indicator of the change in and / or absolute value of the patient's blood oxygen saturation. Thus, control of a patient's blood oxygen level is traditionally achieved by controlling and monitoring the partial pressure of oxygen, which serves as a surrogate indicator of oxygen saturation.

[0005] However, controlling oxygenation based on partial pressure presents significant problems. Specifically, a patient's blood oxygen saturation reaches 100% saturation at a specific oxygen partial pressure (e.g., 100–125 mmHg), and further increases in partial pressure no longer affect blood saturation. Therefore, monitoring oxygen partial pressure leads to the conventional practice of clinicians intentionally maintaining a "too high" oxygen partial pressure (e.g., 200–300 mmHg) to ensure 100% oxygen saturation is achieved. (For comparison, a healthy oxygen partial pressure is considered to be in the range of 75–100 mmHg.)

[0006] While this traditional approach may reduce the risks associated with hypoxia (i.e., hypoxia), it exposes the patient to the lesser-known risks associated with hyperoxia, which can occur when the patient's metabolic rate is reduced, particularly during surgery (e.g., during circulatory arrest).

[0007] Therefore, conventional approaches can cause significant physiological harm to such patients. Exposing such patients' blood to high levels of oxygen can lead to an increased risk of hyperoxia and oxidative stress, which in turn can lead to an increased risk of damage to the patient's cardiovascular or nervous system (e.g., cardiac arrest and stroke).

[0008] Traditional approaches can also cause physiological harm to patients suffering from low blood oxygen saturation. For example, a specific patient population that may be susceptible to these adverse effects is cyanotic patients, a condition caused by low oxygen saturation in the blood, which typically leads to a blue discoloration of the skin. This condition commonly occurs among infants, especially those with congenital heart disease.

[0009] Therefore, there is a need to provide systems and methods for controlling blood oxygenation with improved accuracy and safety.

[0010] It should be noted that for accuracy, and in line with convention in the medical field, pressure values ​​given herein are given in units of mmHg ("millimeters of mercury"). However, these values ​​can be simply converted to atm ("atmospheres") by noting that 1 atm is equal to 760 mmHg, or to Pa ("Pascals") by noting that 1 mmHg is equal to approximately 133.3 Pa.

[0011] According to a first aspect, there is provided a system for controlling blood oxygenation of a patient, which is defined in claim 1.

[0012] The system includes an oxygenator configured to receive blood from a patient and expose the blood to a constant amount of oxygen as the blood passes through the oxygenator to produce oxygenated blood. The system further includes a sensor disposed downstream from the oxygenator and configured to measure oxygen saturation present in the oxygenated blood. The system further includes a controller configured to receive the measured oxygen saturation from the sensor, calculate a difference between a target oxygen saturation and the measured oxygen saturation, and adjust the amount of oxygen the blood is exposed to in the oxygenator to reduce the difference.

[0013] Advantageously, the sensor measures oxygen saturation in blood after oxygenation by the oxygenator. That is, a sensor "located downstream of the oxygenator" means that the blood passes the sensor after passing through the oxygenator. In other words, the sensor is located downstream relative to the direction of blood flow. In this regard, the oxygen saturation measured by the sensor can be referred to as "arterial oxygen saturation." This is in contrast to "venous oxygen saturation," which is measured upstream of the oxygenator (e.g., immediately after blood leaves the patient or between the venous reservoir and the oxygenator).

[0014] Venous oxygen saturation is significantly affected by a patient's physiological factors. For example, venous oxygen saturation is a function of a patient's metabolic rate, blood flow, hemoglobin level, and other physiological parameters. Therefore, measuring venous oxygen saturation inherently builds uncertainty and a lack of precision into any subsequent control of a patient's blood oxygen level based thereon. To control oxygen saturation based on venous oxygen saturation measurements, clinicians need to understand anesthetic factors, the patient's degree of paralysis, the patient's body temperature, the state of the patient's capillary bed, autonomic responses (e.g., immune or inflammatory responses), and various other factors. Therefore, using a sensor to measure oxygen saturation after oxygenation by an artificial lung improves the accuracy and safety of systems for controlling blood oxygen concentration and saturation.

[0015] As used herein, the term "oxygen saturation" refers to the percentage of oxygenated hemoglobin in a patient's blood relative to the total amount of hemoglobin in the patient's blood. The terms "oxygen saturation" and "blood oxygen saturation" are used interchangeably herein. A sensor configured to "measure oxygen saturation" means that the sensor generates a value that can be interpreted by a controller as a direct representation of oxygen saturation. For example, a sensor may output a digital value equal to the oxygen saturation measured by the sensor, or the sensor may output an analog value (e.g., a voltage) related to (e.g., proportional to) the oxygen saturation measured by the sensor. It should be understood that measuring oxygen saturation (e.g., by a sensor) is different from calculating oxygen saturation, which may involve measuring ancillary physiological parameters (e.g., oxygen partial pressure) and applying mathematical operations to these ancillary physiological parameters to derive oxygen saturation. The term "adjust" refers to increasing or decreasing a parameter.

[0016] Advantageously, the controller adjusts the amount of oxygen based on the measured oxygen saturation value to reduce the difference between the target saturation and the measured saturation. This control by the controller may be referred to as "closed-loop" control. The closed-loop control is performed with respect to the measured oxygen saturation, rather than with respect to a surrogate indicator of this value (such as oxygen partial pressure). In this respect, the present invention can be thought of as relating to "direct" closed-loop control of oxygen saturation, as compared to conventional "indirect" closed-loop control.

[0017] The controller may be configured to perform some or all of these operations continuously. For example, the controller may be configured to continuously receive the measured saturation levels, continuously calculate the difference, and / or continuously adjust the amount of oxygen. "Continuously" means that the operations may be performed in an ongoing manner without interruption. Alternatively or additionally, the controller may be configured to repeatedly perform some or all of these operations. For example, the controller may be configured to repeatedly receive the measured saturation levels, repeatedly calculate the difference, and / or repeatedly adjust the amount of oxygen. "Repeatedly" means that the operations may be performed at recurring discrete intervals (e.g., once per millisecond, once per second, once per minute).

[0018] By providing closed-loop control of measured oxygen saturation, several advantages are realized. For example, the system can accurately maintain oxygen saturation and respond to changes in the patient's metabolic rate by adjusting the amount of oxygen the blood is exposed to in response to changes in oxygen saturation. This is particularly beneficial in treating patients experiencing a reduced metabolic rate (e.g., a patient undergoing circulatory arrest). Additionally, the system can accurately maintain oxygen saturation at low levels without having to overcompensate to maintain a safe saturation level. This makes the system particularly beneficial in treating patients with low blood oxygen levels (e.g., cyanotic patients). That is, the system may be used to initially match a target oxygen saturation (e.g., the patient's current low saturation level) using closed-loop control, and then slowly adjust (e.g., increase) the oxygen saturation to establish a healthy oxygen saturation. For example, the target oxygen saturation may be taken as a typical oxygen saturation in a healthy patient, e.g., between 95 and 100%, between 98 and 99%, or approximately 98.5% oxygen saturation. Advantageously, an oxygen saturation of 98.5% approximates the oxygen saturation in the blood of a healthy patient. Furthermore, choosing an oxygen saturation below 100% allows "headroom" for further increases in saturation if needed.

[0019] The controller may be configured to receive a target oxygen saturation. Specifically, the target oxygen saturation may be received as an input by the controller. For example, the controller may be configured to receive the target oxygen saturation as an input from a user interface. Alternatively or additionally, the controller may be pre-programmed with the target oxygen saturation. Alternatively or additionally, the controller may be configured to retrieve the target oxygen saturation from a look-up table stored on a local or remote server.

[0020] It will be appreciated that in some embodiments, the sensor may be configured to measure a physiological parameter other than oxygen saturation. That is, while measuring oxygen saturation is preferred for the reasons discussed above, the sensor may generally be configured to measure a physiological parameter indicative of the oxygenation of oxygenated blood. In such embodiments, the controller may also be configured to perform any or all of the operations described herein, particularly those operations related to controlling the oxygenated gas present in the oxygenator. Operations may be performed with respect to controlling the measured physiological parameter rather than specifically controlling oxygen saturation. For example, the physiological parameter may include oxygen partial pressure.

[0021] In some embodiments, the sensor is placed on a blood line, the blood line being configured to connect to an oxygenator and carry oxygenated blood from the oxygenator to a patient.

[0022] In other words, the sensor may be located between the oxygenator and the patient. That is, the sensor may be located upstream of the patient. The blood line may connect the oxygenator directly to the patient. In such an example, the sensor may be integral with the oxygenator (e.g., integral with the blood outlet of the oxygenator), or the sensor may be separate from the oxygenator and connectable to the blood line. Alternatively, additional components of the system (e.g., sensors, fluid delivery devices, valves, and / or actuators) may be located between the oxygenator and the sensor and / or between the sensor and the patient.

[0023] Advantageously, the sensor is configured to measure "arterial oxygen saturation" (abbreviated as "SaO2") by placing the sensor on a blood line configured to carry oxygenated blood from the oxygenator to the patient. SaO2 is defined as the oxygen saturation in a patient's arterial blood measured directly from the blood. In the field of cardiac perfusion, SaO2 is considered to be the "true" value of oxygen saturation in a patient's arterial blood. This is in contrast to the so-called "peripheral" oxygen saturation in arterial blood (abbreviated as "SpO2"). SpO2 is considered to be an estimate of SaO2 and is measured using pulse oximetry.

[0024] Pulse oximetry involves placing a device called a pulse oximeter on a patient's peripheral body (e.g., ear, finger, toe, hand, or foot) and measuring oxygen saturation through the patient's skin. Pulse oximeters may include a light-emitting component and a light sensor. Here, the light-emitting component shines light of various wavelengths through the patient's skin onto blood vessels, and the light sensor detects reflected light to determine the level of oxygen present in the patient's blood. In this regard, pulse oximetry is performed directly on the patient, not on a blood line configured to carry oxygenated blood from an oxygenator to the patient. Therefore, saturation measured using pulse oximetry is considered less accurate because the patient's body may have already absorbed an unknown amount of oxygen before the blood reaches the point on the body where saturation is measured using pulse oximetry. Furthermore, measuring saturation through the patient's skin, as in pulse oximetry, introduces inaccuracies due to, for example, variations in light absorption by the patient's skin. Therefore, since SpO2 is considered merely an estimate of SaO2, placing a sensor on a blood line configured to carry oxygenated blood from an oxygenator to a patient has the effect of allowing for obtaining an accurate value of oxygen saturation, which in turn allows for accurate control of blood oxygenation in the patient.

[0025] In some embodiments, the sensor is configured to measure the oxygen saturation present in oxygenated blood via spectrophotometry performed on the blood line.

[0026] Advantageously, spectrophotometry provides an accurate means of measuring blood oxygen saturation. Furthermore, spectrophotometry is a noninvasive method that can be performed intraoperatively (e.g., to measure pH or temperature) without contacting the patient's blood. Performing spectrophotometry on the bloodline further improves the accuracy of the measurement because, as noted above, the measurement is performed directly on the blood itself, thus providing a measurement of SaO2 (rather than SpO2, which is measured through the patient's skin via pulse oximetry). Spectrophotometry involves a white light source being shone onto the blood in the bloodline. The white light is at least partially reflected by the blood, and the reflected light is detected by a receiver. The receiver detects only wavelengths reflected by the blood, not wavelengths absorbed by the blood. Some wavelengths of white light are strongly absorbed by oxygenated hemoglobin, while other wavelengths are strongly absorbed by deoxygenated hemoglobin. By measuring the absorption at each wavelength and comparing the relative absorption, the ratio of deoxygenated to oxygenated hemoglobin can be determined, which can then be used to determine the oxygen saturation in the blood.

[0027] To aid in spectrophotometry, the blood line may be transparent, for example, the blood line may be transparent to each wavelength of light used in spectrophotometry.

[0028] Alternatively, the sensor may be configured to measure the oxygen saturation present in oxygenated blood via an invasive method performed on the blood line. In either case, the sensor may include a cuvette.

[0029] In some embodiments, the controller is configured to regulate the amount of oxygen by adjusting the oxygen concentration in the oxygenated gas received by the oxygenator.

[0030] The oxygenator may be configured to expose blood to an oxygenated gas to produce oxygenated blood. The oxygenated gas may include a mixture of oxygen and nitrogen and / or carbon dioxide. For example, the oxygenated gas may include a mixture of nitrogen and oxygen (but no carbon dioxide). Adjusting the oxygen concentration in the oxygenated gas may include adjusting the relative proportions of nitrogen, carbon dioxide, and / or oxygen in the oxygenated gas. The "oxygen concentration in the oxygenated gas" may equivalently be referred to as "fraction of inspired oxygen" (abbreviated "FiO2"). The controller may be configured to adjust the oxygen concentration in the oxygenated gas in communication with one or more valves or actuators that control the gas supply to the oxygenator.

[0031] The ability to adjust the oxygen concentration in the oxygenated gas received by the oxygenator can improve the system's effectiveness in preventing hyperoxia. To explain, a patient's metabolic activity can slow significantly during cardiac perfusion. When metabolic activity slows, supplying pure oxygen to the oxygenator can increase the patient's oxygen saturation, even at low pure oxygen flow rates. By adjusting the oxygen concentration in the oxygenated gas, the system can maintain target oxygen saturation even when the patient's metabolic activity slows.

[0032] The system may further include a gas blender configured to receive one or more supply gases and blend the supply gases to generate one or more oxygenated gases for delivery to the oxygenator. For example, the gas blender may be configured to receive an oxygen gas supply, a nitrogen gas supply, and / or a carbon dioxide gas supply. The oxygen gas supply may include a pure oxygen gas supply (i.e., the oxygen gas supply consists of 100% oxygen). The nitrogen gas supply may include a pure nitrogen gas supply (i.e., the nitrogen gas supply consists of 100% nitrogen). Alternatively, the nitrogen gas supply may include a gas mixture including nitrogen (e.g., the nitrogen gas supply may be air or may include air). The carbon dioxide gas supply may include a pure carbon dioxide gas supply (i.e., the carbon dioxide gas supply consists of 100% carbon dioxide). Alternatively, the carbon dioxide gas supply may include a gas mixture including carbon dioxide (e.g., the carbon dioxide gas supply may be air or may include air). The gas blender may be configured to blend the oxygen gas supply with the nitrogen gas supply and / or the carbon dioxide gas supply to generate one or more oxygenated gases. It should be noted that blending of the feed gases may produce an oxygenated gas consisting of only one of the feed gases (e.g., a gas blender may provide an oxygenated gas consisting of 100% oxygen). The controller may be configured to control the gas blender to adjust the oxygen concentration and / or flow rate of the oxygenated gas.

[0033] It will be understood that the oxygenated gas may include additional gas components. For example, the oxygenated gas may additionally include one or more anesthetic gases (e.g., isoflurane, sevoflurane, desflurane, and / or nitrous oxide). The oxygenated gas may additionally or alternatively include other gases common in the art (e.g., helium and / or argon).

[0034] In some embodiments, the controller is configured to regulate the amount of oxygen by adjusting the flow rate of oxygenated gas received by the oxygenator.

[0035] It will be appreciated that adjusting the flow rate of oxygenated gas has the effect of adjusting the amount of oxygenated gas present in the oxygenator at a given time. Thus, adjusting the flow rate of oxygenated gas adjusts the amount of oxygenated gas to which blood is exposed in the oxygenator. For oxygenated gases that contain oxygen, this adjusts the amount of oxygen to which blood is exposed in the oxygenator. For example, increasing the flow rate of oxygenated gas increases the amount of oxygenated gas present in the oxygenator, thereby increasing the amount of oxygen to which blood is exposed.

[0036] The controller may be configured to adjust both the oxygen concentration in the oxygenated gas and the flow rate of the oxygenated gas. For example, the controller may be configured to adjust the oxygen concentration in the oxygenated gas and the flow rate of the oxygenated gas simultaneously.

[0037] In some embodiments, the oxygenated gas consists of pure oxygen.

[0038] Advantageously, oxygenated gas, consisting solely of oxygen, does not contain any nitrogen. Nitrogen is the main component of gaseous microemboli (GMEs), i.e., gas bubbles, in the blood passing through the oxygenator. Essentially, nitrogen does not dissolve in blood, leading to the formation of GMEs. These GMEs can grow in size by accumulating a layer of blood-derived substances (e.g., blood proteins) on their outer surface. GMEs act as obstructions in the blood and can lead to serious complications, such as tissue or organ damage. The nitrogen concentration in the oxygenated gas is too high when the partial pressure of nitrogen in the oxygenated gas is similar to or substantially equal to the partial pressure of nitrogen in blood. This results in reduced (or virtually no) removal of nitrogen from the blood as it passes through the oxygenator due to the lack of a diffusion gradient between the nitrogen in the blood and the nitrogen in the oxygenated gas. As a result, due to the high nitrogen content of blood, there is also a lack of a diffusion gradient between the nitrogen in the GMEs and the nitrogen in the blood itself. Therefore, little or no diffusion of nitrogen from the GME to the blood or from the blood to the oxygenated gas increases the risk that the GME will continue to pass through the bloodstream unaltered by the oxygenator. By providing pure oxygenated gas, a large diffusion gradient is created between the blood and the oxygenated gas, which in turn creates a large diffusion gradient between the GME and the surrounding blood. Thus, more nitrogen moves from the blood to the oxygenated gas and more nitrogen moves from the GME to the blood. This maximizes nitrogen removal, thereby significantly or completely reducing the risk of GME.

[0039] In some embodiments, the oxygenator includes a gas-blood interface configured to deliver oxygenated gas to expose the blood to that amount of oxygen, and the controller may optionally be configured to adjust the amount of oxygen by adjusting the proportion of the gas-blood interface delivered with oxygenated gas.

[0040] The term "gas-blood interface" refers to the component of the oxygenator that allows gas exchange between the gas supplied to the gas-blood interface and the blood supplied to the gas-blood interface. By adjusting the percentage of the gas-blood interface that is supplied with oxygenated gas, the system can control the blood's exposure to the oxygenated gas. That is, as blood passes through the oxygenator, it passes through a certain percentage of the gas-blood interface that is supplied with oxygenated gas and a certain percentage of the gas-blood interface that is not supplied with oxygenated gas. The blood can therefore exchange gas (and thus be oxygenated) only at a certain percentage of the gas-blood interface.

[0041] Advantageously, this provides a mechanism for adjusting the amount of oxygen the blood is exposed to, independently of the composition of the oxygenated gas. This means that the oxygenator can be used with standard gas supply lines that may already be installed in an operating room, for example. In such instances, the oxygenated gas may contain a mixture of oxygen and nitrogen or may consist of pure oxygen. In the former case, the amount of oxygen the blood is exposed to may be adjusted by adjusting the proportion of the gas-blood interface to which the oxygenated gas is supplied and / or by adjusting the oxygen concentration in the oxygenated gas. In the latter case, the amount of oxygen the blood is exposed to may be adjusted by adjusting the proportion of the gas-blood interface to which the oxygenated gas is supplied while maintaining a supply of pure oxygen, thus reducing the risk of GME as described above.

[0042] The gas-blood interface may include one or more hollow fiber groups. Each hollow fiber group may include multiple hollow fibers. Each hollow fiber group may take the form of a hollow fiber bundle, hollow fiber mat, hollow fiber spiral, or other hollow fiber configuration known in the art.

[0043] Each hollow fiber in a hollow fiber group can include an opening for receiving oxygenated gas. Each hollow fiber can include a gas permeable wall that allows gas exchange between the blood and the oxygenated gas. The hollow fiber group can be positioned across the blood flow (e.g., perpendicularly) to expose the blood to the oxygenated gas present within the hollow fiber group as the blood passes through the oxygenator.

[0044] In some embodiments, the gas-blood interface includes multiple interface regions, each configured to be independently supplied with a respective oxygenated gas, and the controller may be configured to adjust the percentage of the gas-blood interface that is supplied with oxygenated gas by varying the number of interface regions that are supplied with oxygenated gas.

[0045] The interface regions may be arranged sequentially relative to the direction of blood flow through the oxygenator, i.e., as blood passes through the oxygenator, it passes through each interface region in turn.

[0046] "Independently supplied" means that the composition (e.g., gas concentration) and / or flow conditions (e.g., flow rate) of each gas supply can be independently controlled for each interface region. The controller may be configured to change the number of interface regions to which oxygenated gas is supplied by switching one or more independent gas supplies on or off. For example, the controller may be configured to open or close one or more valves that allow or prevent gas flow from the independent gas supplies to the respective interface regions. In such an example, the gas-blood interface may include multiple hollow fiber groups, each hollow fiber group corresponding to a respective one of the interface regions. Alternatively, the gas-blood interface may include a single hollow fiber group, each interface region corresponding to a portion of the single hollow fiber group.

[0047] Alternatively or additionally, the controller may be configured to independently adjust the composition and / or flow rate of the oxygenated gas supplied to each interface region, i.e., more than one of the interface regions may be supplied with oxygenated gas, but the composition and / or flow rate of this oxygenated gas may be varied for each interface region independently from the composition and / or flow rate at the other interface regions.

[0048] The ability to independently adjust the composition and / or flow rate of the oxygenated gas delivered to each interface region can further improve the system's effectiveness in preventing hyperoxia in patients with reduced metabolic activity. For example, the system can maintain target oxygen saturation in such patients by reducing (or halting) the flow rate of the oxygenated gas delivered to one interface region while also reducing the oxygen concentration in the oxygenated gas delivered to another interface region. Because the system can accommodate numerous combinations of the composition and / or flow rate of the oxygenated gas delivered to each interface region, it allows for effective control of oxygen saturation in a wide variety of clinical situations.

[0049] In some embodiments, the oxygenator includes a gas inlet zone for receiving oxygenated gas from each independent gas supply to the gas-blood interface. The gas inlet zone may include one or more partitions that divide the gas inlet zone into multiple gas inlet regions. Each gas inlet region may be configured to receive oxygenated gas from a different one of the respective oxygenated gases. Each gas inlet region may be configured to provide oxygenated gas to a respective interface region.

[0050] In such an example, the gas-blood interface may include multiple hollow fiber groups, each hollow fiber group corresponding to one of the interface regions, i.e., one of the gas inlet regions. Alternatively, the gas-blood interface may include a single hollow fiber group, and each interface region (i.e., each gas inlet zone) may correspond to a portion of a single hollow fiber group.

[0051] One or more partitions may separate the gas-blood interfaces. For example, a partition may extend from the gas inlet zone into and through the gas-blood interface. If the gas-blood interface includes multiple hollow fiber groups, the hollow fiber groups may be separated from each other by gaps in which the partitions are located.

[0052] At least one of the one or more partitions may be movable. For example, the one or more partitions may be movable to adjust the relative size of each gas inlet area. The controller may be configured to adjust the position of the one or more partitions (e.g., by activating a motor coupled to the one or more partitions). For example, the controller may be configured to receive an input representing a desired oxygen saturation level and / or a desired position of the one or more partitions. The controller may be further configured to adjust the position of the one or more partitions in response to the input. The controller may be further configured to convert the desired oxygen saturation level into a position of the one or more partitions. For example, adjusting one or more partitions to increase the size of the interface area through which the oxygenated gas is delivered may increase the exposure of blood to the oxygenated gas, thereby increasing the oxygen saturation in the blood.

[0053] In some embodiments, the oxygenator includes a gas-blood interface configured to receive an oxygenated gas to expose the blood to a quantity of oxygen. The gas-blood interface may optionally include a first interface region configured to receive the first oxygenated gas and a second interface region configured to receive the second oxygenated gas. The first interface region and the second interface region may collectively comprise the entire gas-blood interface.

[0054] In other words, the gas-blood interface is divided into only two interface areas. Thus, it is understood that whatever proportion of the gas-blood interface forms a first interface area, the remaining proportion of the gas-blood interface forms a second interface area. The first interface area may be smaller, larger, or equal in size to the second interface area.

[0055] For example, the gas-blood interface may be split in half, with the first interface area and the second interface area each constituting 50% of the gas-blood interface (i.e., a "50 / 50 split"). In another example, the first interface area may constitute 40% of the gas-blood interface and the second interface area may constitute 60% of the gas-blood interface (i.e., a "40 / 60 split"), or vice versa (i.e., a "60 / 40 split"). Advantageously, a first interface area constituting 40% of the gas-blood interface provides for appropriate regulation (e.g., addition, removal, and / or maintenance) of carbon dioxide when oxygenated gas is delivered to the first interface area at a standard flow rate commonly used during perfusion procedures (e.g., the oxygenated gas flow rate is approximately the same as the blood flow through the oxygenator, e.g., about 4 to 5 liters per minute). Other possible divisions are also contemplated herein, such as a 30 / 70 split, a 70 / 30 split, a 25 / 75 split, a 75 / 25 split, a 20 / 80 split, an 80 / 20 split, a 10 / 90 split, or a 90 / 10 split.

[0056] In some embodiments, the controller is configured to initially adjust the amount of oxygen the blood is exposed to by only supplying the first oxygenated gas to the first interface region without supplying the second oxygenated gas to the second interface region. The controller may be further configured to adjust the amount of oxygen the blood is exposed to by adjusting the oxygen concentration and / or flow rate of the first oxygenated gas. The controller may be further configured to subsequently adjust the amount of oxygen by commencing supply of the second oxygenated gas to the second interface region to increase the amount of oxygen the blood is exposed to.

[0057] The controller may be configured to increase or decrease the amount of oxygen to which the blood is exposed by increasing or decreasing the oxygen concentration and / or flow rate of the first oxygenated gas.

[0058] Advantageously, this feature allows blood to be initially exposed to a small amount of oxygen by delivering only a portion of the gas-blood interface (rather than delivering the entire gas-blood interface). That is, blood is exposed to oxygenated gas only at the first interface region, and thus can only exchange gas while at the first interface region of the gas-blood interface. This is particularly advantageous when treating a patient currently experiencing a reduced metabolic rate (e.g., a patient undergoing circulatory arrest) and / or a patient experiencing reduced oxygen saturation (e.g., a cyanotic patient). This feature allows, for example, selecting a patient's current oxygen saturation as the target oxygen saturation (e.g., to initially match treatment to the patient's current clinical condition), even if the patient's current oxygen saturation is very low.

[0059] Initially, supplying the first oxygenated gas solely to the first interface region may include supplying the first oxygenated gas consisting of pure oxygen. Advantageously, supplying pure oxygen solely to the first interface region (e.g., 40% of the gas-blood interface) provides a sufficiently high diffusion gradient for carbon dioxide between the blood passing through the oxygenator and the first oxygenated gas to ensure adequate removal of carbon dioxide from the blood.

[0060] In particular, this feature allows the system to expose the blood to less oxygen (and thus operate at a lower oxygen saturation) than if oxygenated gas were delivered to the entire gas-blood interface. As an example, delivering oxygenated gas containing 20% ​​oxygen to the entire gas-blood interface will expose the blood to more oxygen than delivering oxygenated gas containing 20% ​​oxygen to only 40% of the gas-blood interface.

[0061] Advantageously, this feature also allows the system to gradually increase oxygen saturation by gradually increasing the oxygen concentration and / or flow rate of the first oxygenated gas. That is, the controller may be configured to increase the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate in the first oxygenated gas. This allows the amount of oxygen to which the blood is exposed to gradually increase, thereby increasing the patient's blood oxygen saturation (i.e., as measured by the sensor).

[0062] At a certain point, the system can begin to supply a second oxygenated gas to the second interface region to further increase the amount of oxygen the blood is exposed to, thus further increasing the oxygen saturation in the patient's blood.

[0063] In general, the first oxygenated gas may be the same as or different from the second oxygenated gas. For example, the first oxygenated gas may be supplied from a first gas supply that is independent of the second gas supply that supplies the second oxygenated gas. This allows the flow rates and / or compositions of the first oxygenated gas and the second oxygenated gas to be independently adjusted. Alternatively, the first oxygenated gas and the second oxygenated gas may be supplied from a single gas supply. In this case, the controller may be configured to independently adjust the flow rates of the first oxygenated gas and the second oxygenated gas by controlling which interface area is supplied by the single gas supply. However, in such an example, it may not be possible to change the composition of the first oxygenated gas independently from the second oxygenated gas.

[0064] In some embodiments, the controller is configured to initiate delivery of the second oxygenated gas in response to the oxygen concentration in the first oxygenated gas increasing to a threshold concentration.

[0065] That is, the controller first increases the oxygen concentration in the first oxygenated gas until the oxygen concentration reaches a threshold concentration, at which point the controller begins supplying a second oxygenated gas to the second interface region. For example, the threshold concentration may be 100%. In this case, the controller increases the oxygen concentration in the first oxygenated gas until it cannot be increased any further. That is, at this stage, the amount of oxygen to which the blood is exposed is at its maximum while gas is being supplied only to the first interface region. At this stage, a second oxygenated gas is supplied to the second interface region to continue increasing the amount of oxygen to which the blood is exposed. The threshold concentration need not be 100% but may instead be another value appropriate for a particular clinical situation.

[0066] In some embodiments, the controller is configured to adjust the amount of oxygen the blood is exposed to by supplying a first oxygenated gas to the first interface region and a second oxygenated gas to the second interface region. The controller may be further configured to adjust the amount of oxygen the blood is exposed to by adjusting the oxygen concentration and / or flow rate of the second oxygenated gas.

[0067] The controller may be configured to increase or decrease the amount of oxygen to which the blood is exposed by increasing or decreasing the oxygen concentration and / or flow rate of the second oxygenated gas.

[0068] Advantageously, this feature allows for the oxygen saturation to be adjusted while exposing the blood to a "high" amount of oxygen within the oxygenator. That is, oxygenated gas is delivered across the entire gas-blood interface. Thus, the blood is exposed to oxygenated gas at both the first and second interface regions, allowing gas exchange across the entire gas-blood interface. This is particularly advantageous when a patient requires a "normal" or "healthy" oxygen saturation (e.g., 98.5%).

[0069] In some embodiments, the controller is further configured to adjust the amount of oxygen to which the blood is exposed by reducing the oxygen concentration in the first oxygenated gas in response to the flow rate of the second oxygenated gas being reduced to a threshold flow rate.

[0070] That is, the controller first reduces the flow rate of the second oxygenated gas until the flow rate reaches a threshold flow rate, at which point the controller begins to reduce the oxygen concentration of the first oxygenated gas. For example, the threshold flow rate may be zero (i.e., there is no longer any flow of the second oxygenated gas in the second interface region). In this case, the controller reduces the flow rate of the second oxygenated gas until it cannot be reduced any further. Thus, at this stage, the amount of oxygen to which the blood is exposed is at the minimum level achievable by controlling only the flow rate of the second oxygenated gas. At this stage, the oxygen concentration in the first oxygenated gas is reduced to continue to reduce the amount of oxygen to which the blood is exposed. The threshold flow rate need not be zero, but may instead be another value appropriate for a particular clinical situation.

[0071] In some embodiments, the target oxygen saturation is a first target oxygen saturation. The controller may be further configured to increase the oxygen concentration and / or flow rate of the first oxygenated gas to reach a second target oxygen saturation in response to the sensor measuring an oxygen saturation equal to the first target oxygen saturation. Alternatively or additionally, the controller may be further configured to initiate delivery of a second oxygenated gas to reach the second target oxygen saturation in response to the sensor measuring an oxygen saturation equal to the first target oxygen saturation. The second target oxygen saturation may be higher than the first target oxygen saturation.

[0072] The controller may be configured to increase or decrease the oxygen concentration and / or flow rate of the first oxygenated gas to reach a first target oxygen saturation.

[0073] The first target oxygen saturation may be equal to the patient's current oxygen saturation. The patient's current oxygen saturation may be measured, for example, by the sensor or a peripheral sensor connected to the patient (e.g., a pulse oximeter). Alternatively, the patient's current oxygen saturation may be assumed (or estimated) based on the patient's known physiological parameters (e.g., average oxygen saturation based on known physiological parameters). For a cyanotic patient, the first target oxygen saturation may be 75% or less.

[0074] The second target oxygen saturation may be equal to the desired oxygen saturation of the patient's blood. For example, the desired oxygen saturation may be selected to be an oxygen saturation typical of a healthy patient. For example, the second target oxygen saturation may be in the range of 95-100%, in the range of 98-99%, or approximately 98.5%. Alternatively, the desired oxygen saturation may be an intermediate value between the patient's current oxygen saturation and the oxygen saturation of a healthy patient, to further gradually increase the patient's oxygen saturation. For example, the second target oxygen saturation may be in the range of 80-95%. The second target oxygen saturation may be iteratively adjusted (e.g., increased) until the patient's oxygen saturation is at the oxygen saturation of a typical healthy patient.

[0075] The controller may be configured to receive the second target oxygen saturation. More specifically, the second target oxygen saturation may be received by the controller as an input. For example, the controller may be configured to receive the second target oxygen saturation as an input from a user interface. Alternatively or additionally, the controller may be pre-programmed with the second target oxygen saturation. Alternatively or additionally, the controller may be configured to obtain the second target oxygen saturation from a look-up table stored on a local or remote server.

[0076] In some embodiments, the controller is configured to further adjust the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate of the second oxygenated gas.

[0077] The controller may be configured to further increase or decrease the amount of oxygen to which the blood is exposed by increasing or decreasing (i) the oxygen concentration in the second oxygenated gas and / or (ii) the flow rate of the second oxygenated gas.

[0078] Advantageously, this allows for adjustment of the amount of oxygen the blood is exposed to even after both the first and second interface regions have been supplied with oxygenated gas, which in turn allows for an increase in oxygen concentration up to 100% across both the first and second interface regions, and therefore an increase in the amount of oxygen the blood is exposed to, up to its maximum possible value.

[0079] In some embodiments, the controller is further configured to decrease the flow rate of the second oxygenated gas in response to the sensor measuring an oxygen saturation level that is greater than the first target oxygen saturation. The controller may be further configured to decrease the oxygen concentration in the first oxygenated gas after decreasing the flow rate and in response to the sensor measuring an oxygen saturation level that remains greater than the target oxygen saturation.

[0080] In some embodiments, the system further includes a venous reservoir configured to receive blood from the patient. The system may optionally further include a pump configured to drive blood flow from the venous reservoir through the oxygenator.

[0081] The venous reservoir may be located upstream of the oxygenator. The venous reservoir may be configured to be located between the oxygenator and the patient. That is, the venous reservoir may receive deoxygenated blood from the patient. The pump may be configured to withdraw deoxygenated blood from the venous reservoir and to infuse the deoxygenated blood into the oxygenator. The pump may be located upstream of the oxygenator. The pump may be located downstream of the venous reservoir. The pump may be located between the venous reservoir and the oxygenator. The pump may be a centrifugal pump or a roller (peristaltic) pump.

[0082] Also disclosed herein is a method of controlling blood oxygenation in a patient with an oxygenator configured to receive blood from a patient and expose the blood to a constant amount of oxygen as the blood passes through the oxygenator to produce oxygenated blood.

[0083] The method includes measuring oxygen saturation present in oxygenated blood downstream of the oxygenator, calculating a difference between a target oxygen saturation and the measured oxygen saturation, and adjusting the amount of oxygen the blood is exposed to in the oxygenator to reduce the difference.

[0084] In some embodiments, the oxygen saturation present in the oxygenated blood is measured on a blood line connected to the oxygenator and configured to carry the oxygenated blood from the oxygenator to the patient.

[0085] In some embodiments, measuring oxygen saturation includes performing spectrophotometry on blood in the bloodline.

[0086] In some embodiments, adjusting the amount of oxygen comprises adjusting the oxygen concentration in the oxygenated gas received by the oxygenator.

[0087] In some embodiments, the oxygenated gas consists of pure oxygen.

[0088] In some embodiments, the oxygenator includes a gas-blood interface that is supplied with oxygenated gas to expose the blood to the amount of oxygen, and adjusting the amount of oxygen can include adjusting the percentage of the gas-blood interface that is supplied with oxygenated gas.

[0089] In some embodiments, the gas-blood interface includes multiple interface regions, each configured to be independently supplied by a respective oxygenated gas, and adjusting the proportion of the gas-blood interface supplied with oxygenated gas may include varying the number of interface regions supplied with oxygenated gas.

[0090] In some embodiments, the oxygenator includes a gas-blood interface configured to receive an oxygenated gas to expose the blood to the amount of oxygen. The gas-blood interface includes a first interface region configured to receive the first oxygenated gas and a second interface region configured to receive the second oxygenated gas. The first interface region and the second interface region collectively comprise the entire gas-blood interface.

[0091] In some embodiments, adjusting the amount of oxygen to which the blood is exposed initially includes only supplying a first oxygenated gas to the first interface region without supplying a second oxygenated gas to the second interface region. Adjusting the amount of oxygen to which the blood is exposed may further include adjusting the oxygen concentration and / or flow rate of the first oxygenated gas. Adjusting the amount of oxygen may further include subsequently commencing supply of a second oxygenated gas to the second interface region of the gas-blood interface to increase the amount of oxygen to which the blood is exposed.

[0092] In some embodiments, initiating the delivery of the second oxygenated gas is in response to the oxygen concentration in the first oxygenated gas increasing to a threshold concentration.

[0093] In some embodiments, adjusting the amount of oxygen to which the blood is exposed comprises supplying a first oxygenated gas to the first interface region and a second oxygenated gas to the second interface region, and may further comprise adjusting the oxygen concentration and / or flow rate of the second oxygenated gas.

[0094] In some embodiments, adjusting the amount of oxygen to which the blood is exposed includes reducing the oxygen concentration in the first oxygenated gas in response to the flow rate of the second oxygenated gas being reduced to a threshold flow rate.

[0095] In some embodiments, the target oxygen saturation is a first target oxygen saturation. The method may further include, in response to measuring an oxygen saturation equal to the first target oxygen saturation, increasing the oxygen concentration and / or flow rate of the first oxygenated gas to reach a second target oxygen saturation. Alternatively or additionally, the method may further include, in response to measuring an oxygen saturation equal to the first target oxygen saturation, initiating the supply of a second oxygenated gas to reach the second target oxygen saturation. The second target oxygen saturation may be higher than the first target oxygen saturation.

[0096] In some embodiments, the method further comprises adjusting the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate of the second oxygenated gas.

[0097] In some embodiments, the method further includes decreasing the flow rate of the second oxygenated gas in response to measuring an oxygen saturation greater than the target oxygen saturation. The method may further include decreasing the oxygen concentration in the first oxygenated gas after decreasing the flow rate and in response to measuring an oxygen saturation that remains greater than the target oxygen saturation. [Brief explanation of the drawings]

[0098] Examples will now be described with reference to the accompanying drawings.

[0099] [Figure 1] FIG. 1 is a schematic diagram of a system for controlling blood oxygenation in a patient. [Figure 2A] FIG. 2A is a schematic diagram of a first example of an artificial lung of a system for controlling blood oxygenation of a patient. [Figure 2B] FIG. 2B is a schematic diagram of a second example of an artificial lung of a system for controlling blood oxygenation of a patient. [Figure 3A] FIG. 3A is a schematic diagram of the oxygenator of FIG. 2B having a first interface region supplied with a first oxygenated gas. [Figure 3B]FIG. 3B is a schematic diagram of the oxygenator of FIG. 2B having a first interface region supplied with a first oxygenated gas and a second interface region supplied with a second oxygenated gas. [Figure 4] FIG. 4 is a flow chart of a first example of a method for controlling blood oxygenation of a patient by an artificial lung. [Figure 5] FIG. 5 is a flow chart of a second example of a method for controlling blood oxygenation of a patient by an artificial lung. [Figure 6] FIG. 6 is a schematic diagram showing the operating state of the oxygenator of FIG. 2B. DETAILED DESCRIPTION OF THE INVENTION

[0100] 1 depicts a system 100 for controlling a patient's blood oxygenation. The patient's position relative to system 100 is indicated by arrow P, which indicates which blood lines (see below) lead to the patient. System 100 includes an oxygenator 200. Oxygenator 200 is configured to receive blood from the patient and expose the blood to a constant amount of oxygen as the blood passes through oxygenator 200 to produce oxygenated blood.

[0101] System 100 further includes sensor 110. Sensor 110 is positioned downstream of oxygenator 200. In the illustrated example, sensor 110 is positioned upstream of the patient on the blood line (in this case, arterial line 132) exiting oxygenator 200. Sensor 110 is configured to measure the oxygen saturation present in oxygenated blood (i.e., in the blood after oxygenation by oxygenator 200). For example, sensor 110 may be configured to measure the oxygen saturation present in oxygenated blood via spectrophotometry performed in arterial line 132. In this case, sensor 110 is considered to measure "arterial oxygen saturation" (SaO2). It is understood that other techniques for measuring oxygen saturation may be used in sensor 110.

[0102] System 100 further includes a controller 150. Controller 150 is configured to receive the measured oxygen saturation from sensor 110. Controller 150 is further configured to calculate the difference between the target oxygen saturation and the measured oxygen saturation. Controller 150 is further configured to adjust the amount of oxygen the blood is exposed to in oxygenator 200 to reduce the difference. The functionality of controller 150 is described in detail below with reference to Figures 3A through 5.

[0103] Controller 150 is communicatively connected to oxygenator 200 and sensor 110, as shown by the dashed-dotted lines in FIG. 1 . That is, controller 150 may be configured to communicate with oxygenator 200 and sensor 110. This communication may occur via a hard connection (e.g., a wired connection) or wireless communication. In this regard, it is understood that the dashed-dotted lines depicted in FIG. 1 are merely exemplary and do not necessarily represent physical connections between components. Furthermore, it is understood that controller 150 may be communicatively connected to more or fewer components in system 100. For example, controller 150 need not necessarily communicate directly with oxygenator 200, but instead may be configured to communicate with valves, actuators, and / or other gas flow control mechanisms that control gas flow to and / or from oxygenator 200. Similarly, controller 150 need not necessarily communicate directly with sensor 110, but instead may be configured to communicate with an intermediate transceiver that relays measurements from sensor 110 to controller 150. The controller 150 may be further configured to communicate with the pump 130 and / or other components present in the system 100. Other arrangements of communication connections between components will be readily appreciated by those skilled in the art.

[0104] It should be noted that "communication" with the controller 150 refers to both the receipt of data (e.g., measurements) by the controller 150 and the transmission of data (e.g., instructions or commands) by the controller 150.

[0105] The controller 150 may include any suitable type of data processing device, such as a microprocessor, microcontroller, or application specific integrated circuit (ASIC), which may be communicatively coupled to memory (e.g., volatile memory, non-volatile memory, or both volatile and non-volatile memory) that stores processor-executable instructions that cause the controller to perform any of the methods disclosed herein.

[0106] As shown in FIG. 1 , system 100 is configured to receive blood from a patient via venous line 122 and return blood to the patient via arterial line 132. The connection of system 100 to the patient is indicated by arrow P in FIG. 1 . System 100 further includes a venous reservoir 120 configured to receive blood from the patient via venous line 122. Venous reservoir 120 may additionally be configured to receive blood from the patient via one or more salvage lines, one or more purge lines, and / or one or more lines configured to carry surgical fluids (e.g., priming solution, volume expander, blood, and / or medications), as represented by line 124 in FIG. 1 . Venous reservoir 120 is positioned between the patient and oxygenator 200, upstream of oxygenator 200. It will be understood that the exact location of venous reservoir 120 and pump 130 may vary in other implementations. Indeed, system 100 need not necessarily include venous reservoir 120 and pump 130. In such cases, the oxygenator 200 may be configured to receive blood directly from the patient.

[0107] Blood is collected in venous reservoir 120 and driven through oxygenator 200 by pump 130. Pump 130 is positioned downstream of venous reservoir 120 and upstream of oxygenator 200. In the depicted embodiment, pump 130 is a roller (or peristaltic) pump. However, it is understood that other types of pumps, such as centrifugal pumps, may be used depending on the circumstances. Blood exits pump 130 and is received by oxygenator 200 via blood inlet 210. The blood is oxygenated by oxygenator 200, then exits the oxygenator via blood outlet 212, passes sensor 110, and is returned to the patient via arterial line 132. The blood flow path through system 100 is indicated in FIG. 1 by arrow A.

[0108] The oxygenator 200 may take a variety of forms. Two examples of oxygenators that may be used in the present system are shown in Figures 2A and 2B. Accordingly, example structures of the oxygenator 200 will now be described with reference to Figures 2A and 2B.

[0109] Beginning with FIG. 2A, oxygenator 200′ is shown. As described above, oxygenator 200′ includes blood inlet 210 for receiving blood from a patient and blood outlet 212 for returning blood to the patient. Oxygenator 200′ further includes gas inlet 222, as indicated by arrow G, for accepting oxygenated gas into oxygenator 200′. Oxygenated gas enters oxygenator 200′ from gas inlet 222 via gas inlet zone 230′. Oxygenator 200′ further includes gas outlet 226 (which may be referred to as gas exhaust 226) for venting waste gas from oxygenator 200′. Oxygenated gas exits oxygenator 200′ from gas outlet 226 via gas outlet zone 231.

[0110] Oxygenator 200' further includes gas-blood interface 240. Gas inlet zone 230' is fluidly connected to gas-blood interface 240. Gas outlet zone 231 is also fluidly connected to gas-blood interface 240. That is, oxygenated gas enters gas-blood interface 240 from gas inlet zone 230 and exits gas-blood interface 240 via gas outlet zone 231.

[0111] The gas-blood interface 240 may include one or more hollow fiber groups, each of which may include multiple hollow fibers. Each hollow fiber group includes an inlet potting fluidly connected to the gas inlet zone 230'. Each hollow fiber group includes an outlet potting fluidly connected to the gas outlet zone 231.

[0112] Gas-blood interface 240 is configured to receive oxygenated gas to expose the blood to a constant amount of oxygen. For example, oxygenated gas may enter the hollow fiber group from gas inlet zone 230' through inlet potting. Blood enters oxygenator 200' through blood inlet 210. The blood and oxygenated gas pass through gas-blood interface 240 as they pass through oxygenator 200'. Gas-blood interface 240 is configured to allow gaseous exchange between the blood and the oxygenated gas supplied to gas-blood interface 240. This includes the transfer of gases (e.g., carbon dioxide, nitrogen) from the blood into the oxygenated gas and the transfer of gases (e.g., oxygen) into the blood and out of the oxygenated gas. After gas exchange, the (now oxygenated) blood exits oxygenator 200' through blood outlet 212 to the patient, and the oxygenated gas (now waste gas) exits oxygenator 200' through gas outlet 226.

[0113] Controller 150 may be configured to adjust the amount of oxygen to which blood is exposed within the oxygenator by adjusting the oxygen concentration in the oxygenated gas received at gas-blood interface 240 from gas inlet 222. Alternatively or additionally, controller 150 may be configured to adjust the amount of oxygen to which blood is exposed within the oxygenator by adjusting the flow rate of oxygenated gas through oxygenator 200′. For example, as shown in FIG. 2A , system 100 may further include valve 224 that controls the flow of oxygenated gas to gas inlet 222. Controller 150 may be configured to control valve 224 (e.g., by opening or closing valve 224) to adjust the amount of oxygenated gas delivered to gas-blood interface 240.

[0114] Alternatively or additionally, the system may further include a gas blender (not shown) configured to blend one or more supply gases to produce one or more oxygenated gases for supply to the oxygenator 200'. The controller 150 may be configured to control the gas blender to adjust the composition (e.g., oxygen concentration) and / or flow rate of the oxygenated gas.

[0115] Turning to FIG. 2B, oxygenator 200'' will now be described. Oxygenator 200'' is similar to oxygenator 200', and like reference numerals are used for like features where appropriate. For the sake of brevity, the description of these like features will not be repeated here. The difference between oxygenator 200' and 200'' lies in the features that allow for the delivery of oxygenated gas to oxygenator 200''.

[0116] While oxygenator 200′ includes a single gas inlet 222 for accepting a single oxygenated gas into oxygenator 200′, oxygenator 200″ includes two gas inlets for accepting two oxygenated gases into oxygenator 200″. Oxygenator 200″ includes a first gas inlet 222a and a second gas inlet 222b. First gas inlet 222a and second gas inlet 222b are each fluidly connected to a gas inlet zone 230″. Gas inlet zone 230″ includes a partition 232 that divides gas inlet zone 230″ into multiple (in this case, two) gas inlet regions 234a, 234b. Each gas inlet region 234a, 234b is configured to receive a different one of the respective oxygenated gases. More specifically, the first gas inlet region 234a is configured to receive oxygenated gas from the first gas inlet 222a, and the second gas inlet region 234b is configured to receive oxygenated gas from the second gas inlet 222b.

[0117] 2B, the presence of multiple gas inlet regions 234a, 234b effectively permits the supply of respective oxygenated gases to different percentages of the gas-blood interface 240. In this regard, the gas-blood interface 240 includes multiple (in this case, two) interface regions 240a, 240b, each configured to be supplied with a respective oxygenated gas independently. In such an example, the controller 150 may be configured to adjust the percentage of the gas-blood interface 140 that is supplied with oxygenated gas by varying the number of interface regions 240a, 240b that are supplied with oxygenated gas.

[0118] The partition 232 shown in FIG. 2 divides the gas inlet zone 230″ into first and second gas inlet regions 234a and 234b of equal size. That is, the partition 232 divides the gas inlet zone 230″ (and thus the gas-blood interface 240) in half, such that the first and second gas inlet regions 234a and 234b each comprise 50% of the gas inlet zone 230″. Furthermore, the partition 232 functions to divide the gas-blood interface 240 in half, such that the first and second interface regions 240a and 240b each comprise 50% of the gas-blood interface 240. However, it will be understood that this division is merely one example, and that the partition 232 (and / or multiple partitions) may be positioned in various locations to create different divisions of the gas inlet zone 230″ and the gas-blood interface 240. For example, the partitions 232 may be positioned such that the first gas inlet area 234a comprises 40% of the gas inlet zone 230'' and the second gas inlet area 234b comprises 60% of the gas inlet zone 230''. That is, the gas-blood interface 240 may be divided such that the first interface area 240a comprises 40% of the gas-blood interface 240 and the second interface area 240b comprises 60% of the gas-blood interface 240.

[0119] The partition 232 shown in FIG. 2 penetrates the gas inlet zone 230″ but not the gas-blood interface 240. In such a case, the partition 232 may abut the inlet potting of the hollow fiber group to prevent gas flow between interface regions 240a, 240b. Alternatively, the partition 232 may not abut the inlet potting, since leakage of gas flow between gas inlet regions 234a, 234b may be tolerated. In other examples, the partition 232 may penetrate the gas inlet zone 230″ and at least partially penetrate the gas-blood interface 240, physically separating the gas-blood interface 240 into interface regions 240a, 240b.

[0120] It is noted that, in general, the oxygenated gas supplied to each of the gas inlet regions 234a, 234b may come from the same or different gas sources. The oxygenated gases may have the same composition or different compositions.

[0121] As described above, system 100 may include one or more valves for controlling the flow of gas to the gas inlets of the oxygenator. In the case of oxygenator 200″, system 100 may include a first valve 224a configured to control the flow of oxygenated gas to first gas inlet 222a and a second valve 224b configured to control the flow of oxygenated gas to second gas inlet 222b. Controller 150 may be configured to control (e.g., open or close) first valve 224a and second valve 224b independently of one another to adjust (e.g., increase or decrease) the flow rate through each interface region 240a, 240b. Alternatively or additionally, system 100 may include a gas blender for controlling gas flow and / or composition, as described above. It will be understood that other examples of valves, actuators, blenders, gas flow controllers, or other components for controlling gas flow rate and / or composition may be used in place of and / or in addition to the valves or gas blenders described herein.

[0122] 3A and 3B, the function of the oxygenator 200'' will be described. As previously explained, the partition 232 allows the gas inlet regions 234a, 234b to be independently supplied with oxygenated gas. Starting with FIG. 3A, the first gas inlet 222a may be supplied with a first oxygenated gas 242a. The first gas inlet 222a may be supplied with the first oxygenated gas 242a without supplying oxygenated gas to the second gas inlet 222b (i.e., oxygenated gas is supplied only to the first gas inlet 222a). This allows the first oxygenated gas 242a to be supplied to the first gas inlet region 234a and, therefore, to the first interface region 240a.

[0123] In this situation, blood passing through oxygenator 200″ is exposed to first oxygenated gas 242a through only a portion (50% in this case) of gas-blood interface 240. That is, the blood is not substantially exposed to oxygenated gas while passing through second interface region 240b. Blood is exposed to first oxygenated gas 242a only as it passes through first interface region 240a. Thus, the amount of oxygen to which blood is exposed within oxygenator 200″ can be kept low. To further adjust (e.g., increase or decrease) the amount of oxygen to which the blood is exposed, the concentration and / or flow rate of first oxygenated gas 242a can be adjusted as described above. It will be appreciated that, depending on the relative sizes of first interface region 240a and second interface region 240b, a similar effect can be achieved by supplying oxygenated gas only to second interface region 240b via second gas inlet 222b.

[0124] 3B, a first oxygenated gas 242a is provided to the first gas inlet 222a as in FIG. 3A, and a second oxygenated gas 242b is provided to the second gas inlet 222b, thereby providing the second oxygenated gas 242b to the second gas inlet region 234b and thus to the second interface region 240b.

[0125] In this situation, blood passing through oxygenator 200″ is exposed to second oxygenated gas 242b as it passes through second interface region 240b, and then to first oxygenated gas 242a as it passes through first interface region 240a. Thus, the amount of oxygen to which blood is exposed within oxygenator 200″ is increased relative to the situation shown in FIG. 3A. To further adjust (e.g., increase and / or decrease) the amount of oxygen to which the blood is exposed, the concentration and / or flow rate of first oxygenated gas 242a and / or second oxygenated gas 242b can be adjusted as described above. It will be understood that the flow rate and / or composition of first oxygenated gas 242a can be adjusted independently from the flow rate and / or composition of second oxygenated gas 242b.

[0126] In this manner, the controller 150 can use the oxygenator 200' or 200'' to control the amount of oxygen that the blood is exposed to within the oxygenator.

[0127] The first oxygenated gas 242a and / or the second oxygenated gas 242b may consist of pure oxygen. The first oxygenated gas 242a and / or the second oxygenated gas 242b may include a mixture of oxygen and nitrogen.

[0128] While specific examples of oxygenators that can be used in system 100 have been described, it is understood that other oxygenators that achieve the same or similar functions may be used. For example, an oxygenator may include multiple gas inlet zones, each connecting to a separate gas inlet. Alternatively, one or more gas inlets may be directly connected to a gas-blood interface, which may be separated into multiple interface regions within the oxygenator. It is understood that other oxygenator configurations exist that allow multiple interface regions to be independently supplied with respective oxygenated gases. Furthermore, while the oxygenator is shown as including one or two gas inlet regions and one or two interface regions, it is understood that virtually any number of gas inlet regions and interface regions may be present. The more gas inlet regions and interface regions there are, the more independent oxygenated gases can be supplied to the gas-blood interface.

[0129] The overall functionality of the system 100 will now be described with reference to FIGS.

[0130] FIG. 4 depicts a first example method 400 of controlling a patient's blood oxygenation as contemplated herein. Controller 150 may be configured to perform any or all of the operations of method 400. Method 400 includes measuring 402 the oxygen saturation present in oxygenated blood. Measuring 402 may be performed, for example, by sensor 110. Method 400 further includes calculating 404 the difference between a target oxygen saturation and the measured oxygen saturation. Method 400 further includes adjusting 408 the amount of oxygen to which the blood is exposed to reduce the difference. Adjusting 408 may include adjusting the composition (e.g., oxygen concentration) and / or flow rate of the oxygenated gas(es) supplied to the oxygenator, as described above with reference to FIGS. 2A-3B . Following adjusting 408 the amount of oxygen to which the blood is exposed, method 400 may include recalculating the difference between the target oxygen saturation and the measured oxygen saturation. Thus, the adjustment 408 and calculation 404 may be repeated and / or performed continuously, as indicated by the return arrows connecting these boxes in FIG.

[0131] Optionally, method 400 (e.g., adjusting 408) may further include delivering 406 the first oxygenated gas 242a only to the first interface region 240a of the gas-blood interface 240. Adjusting 408 may include adjusting the composition (e.g., oxygen concentration) and / or flow rate of the first oxygenated gas 242a.

[0132] Optionally, method 400 (e.g., adjusting 408) may further include starting 410 the supply of second oxygenated gas 242b to second interface region 240b of gas-blood interface 240. Adjusting 408 may include adjusting the composition (e.g., oxygen concentration) and / or flow rate of second oxygenated gas 242b.

[0133] For example, initiating 410 the supply of second oxygenated gas 242b may be in response to the oxygen concentration in first oxygenated gas 242a increasing to a threshold concentration (eg, 100% oxygen).

[0134] In one example scenario, oxygenated gas (in the form of first oxygenated gas 242a) may initially be supplied only to the first interface region 240a. At this stage, the first oxygenated gas 242a may include a mixture of nitrogen and oxygen. In this regard, the blood is exposed to a "low" amount of oxygen (and thus a "low" oxygen saturation may be achieved in the patient's blood). The oxygen concentration in the first oxygenated gas 242a may be gradually increased to increase the amount of oxygen to which the blood is exposed (and thus increase blood oxygen saturation). When the oxygen concentration in the first oxygenated gas 242a reaches 100%, it is no longer possible to increase the amount of oxygen to which the blood is exposed by increasing the oxygen concentration in the first oxygenated gas 242a. Therefore, the supply of the second oxygenated gas 242b is initiated to further increase the amount of oxygen to which the blood is exposed. The oxygen concentration and / or flow rate of the second oxygenated gas 242b can then be further adjusted to adjust the amount of oxygen the blood is exposed to.

[0135] Although operations 406, 408, and 410 in FIG. 4 are shown sequentially for ease of explanation, it is understood that these operations are interrelated, and that, for example, adjust 408 can be considered to include supply 406 and start 410.

[0136] FIG. 5 depicts a second example method 500 of controlling a patient's blood oxygenation as contemplated herein. Controller 150 may be configured to perform any or all of the operations of method 500. Method 500 includes measuring 502 the oxygen saturation present in oxygenated blood. Measuring 502 may be performed, for example, by sensor 110. Method 500 further includes calculating 504 the difference between a first target oxygen saturation and the measured oxygen saturation. Method 500 further includes supplying 506 the first oxygenated gas 242a only to the first interface region 240a of the gas-blood interface 240. Method 500 further includes adjusting 508 the amount of oxygen to which the blood is exposed to reduce the difference. Adjusting 508 may include adjusting the composition (e.g., oxygen concentration) and / or flow rate of the oxygenated gas(es) supplied to the oxygenator, as described above with reference to FIGS. 2A-3B. For example, adjusting 508 may include adjusting the composition (eg, oxygen concentration) and / or flow rate of the first oxygenated gas 242a.

[0137] The method 500 further includes, in response to measuring 510 (e.g., by the sensor 110) an oxygen saturation equal to the first target oxygen saturation, increasing 512 the oxygen concentration and / or flow rate of the first oxygenated gas 242a and / or initiating 514 the supply of a second oxygenated gas 242b to the second interface region 240b of the gas-blood interface 240. The increasing 512 and / or initiating 514 may be performed to reach a second target oxygen saturation. The second target oxygen saturation may be higher than the first target oxygen saturation. The method 500 may further include adjusting 516 the oxygen concentration and / or flow rate of the second oxygenated gas 242b to reach the second target oxygen saturation.

[0138] In one example scenario, oxygenated gas (in the form of first oxygenated gas 242a) is initially supplied only to first interface region 240a. At this stage, first oxygenated gas 242a may include a mixture of nitrogen and oxygen. At this point, a low amount of oxygen (and therefore a low oxygen saturation in the patient's blood) may be achieved. The oxygen concentration in first oxygenated gas 242a may be gradually increased to increase the amount of oxygen to which the blood is exposed (and thus increase the oxygen saturation in the blood) until the oxygen saturation (measured by sensor 110) reaches a first target oxygen saturation (i.e., until there is no difference between the first target oxygen saturation and the measured oxygen saturation). At this stage, a second (e.g., higher) target oxygen saturation may be received or obtained by controller 150 (or selected by the clinician). The oxygen concentration and / or flow rate of the first oxygenated gas 242a at the first interface region 240a may be increased and / or the supply of the second oxygenated gas 242b to the second interface region 240b may be initiated to achieve the second target oxygen saturation. The oxygen concentration and / or flow rate of the second oxygenated gas 242b may then be further adjusted to adjust the amount of oxygen to which the blood is exposed.

[0139] Method 500 may be particularly useful for treating cyanotic patients. A cyanotic patient is a patient suffering from low blood oxygen saturation. During surgery and / or treatment of a cyanotic patient, it is desirable to increase the patient's blood oxygen saturation. However, oxygenating a patient's blood to a high oxygen saturation level too quickly can cause hyperoxia, which can cause physiological damage to the patient. Therefore, in method 500, a first target oxygen saturation level may be selected to be equal to, similar to, or slightly greater (e.g., 1-2%) than the patient's current oxygen saturation, which may be approximately 75% for a cyanotic patient. The oxygen saturation level may be maintained and gradually increased using the closed-loop functionality described herein. A second target oxygen saturation level may then be selected to be higher (e.g., slightly higher, e.g., 1-2%) than the current oxygen saturation. System 100 then increases the blood saturation level (i.e., adjusts the amount of oxygen the blood is exposed to to reduce the difference). The second target oxygen saturation can be repeatedly and incrementally increased until the target oxygen saturation is typical of a healthy patient (e.g., 98-100%), thereby bringing the patient from a cyanotic state to a healthy oxygen saturation.

[0140] The oxygen concentration in first oxygenated gas 242a and second oxygenated gas 242b may be increased to substantially 100% (i.e., pure oxygen). This has the advantage of maximizing the removal of nitrogen from the patient's blood, which in turn reduces the risk of harmful GME formation in the patient's blood. Notably, this increase to 100% may be performed as a final maneuver during the patient's treatment to ensure the removal of GME before the treatment is terminated.

[0141] Turning to Figure 6, an example of the operation of the system described herein will be described. Figure 6 shows a schematic representation of several "states" that may exist in the operation of the system described herein. In particular, Figure 6 shows a series of states that may occur during the treatment of a patient experiencing a low metabolic rate (e.g., undergoing circulatory arrest).

[0142] FIG. 6 is divided into a series of four states (a) through (d), which are described sequentially below. Transitions between states are indicated by arrows 660, 662, 664, and 666. In each state, oxygenator 600 is depicted. For clarity, details of oxygenator 600 are not described or labeled in FIG. 6 . However, it is understood that oxygenator 600 may share any or all of the features of oxygenator 200″ described above. The only features labeled in FIG. 6 are first interface region 640a, second interface region 640b, first oxygenated gas 642a, and second oxygenated gas 642b. While the following description begins with state (a), it is understood that any state can be considered “start” because the process is cyclical.

[0143] In state (a), first interface area 640a is supplied with first oxygenated gas 642a. No oxygenated gas is supplied to second interface area 640b. As shown in FIG. 6, first oxygenated gas 642a is supplied at 100% FiO2. That is, in state (a), first oxygenated gas 642a consists solely of oxygen. Oxygenator 600 may be operated in this state to both oxygenate the patient's blood and remove carbon dioxide from the patient's blood. In this regard, first oxygenated gas 642a may be considered a "sweep gas." However, given that first interface area 640a represents only a percentage (e.g., 40%) of the total gas-blood interface, the supply of first oxygenated gas 642a may not be sufficient to reach a target oxygen saturation in the patient's blood. For example, a sensor may measure an oxygen saturation level below the target oxygen saturation. The system may then transition to state (b), as indicated by arrow 660.

[0144] In state (b), the first interface region 640a continues to be supplied with the first oxygenated gas 642a at 100% FiO2. However, the second interface region 640b now begins to be supplied with the second oxygenated gas 642b. That is, the flow rate of the second oxygenated gas 642b may be increased from zero. The flow rate of the second oxygenated gas 642b may continue to be increased until a target oxygen saturation level in the patient's blood is reached (e.g., until a sensor measures an oxygen saturation level equal to the target oxygen saturation level). It will be appreciated that by supplying the second oxygenated gas 642b to the second interface region 640b, the amount of oxygen to which the blood is exposed increases beyond the amount possible by supplying only the first interface region 640a. Thus, high oxygen saturation levels may be achieved by supplying both interface regions 640a, 640b. The second oxygenated gas 642b may be provided at 100% FiO (i.e., pure oxygen). The oxygen concentration in the second oxygenated gas 642b may be adjusted in addition to or instead of adjusting the flow rate of the second oxygenated gas 642b. The system may operate in this state to increase the oxygen saturation in the patient's blood to a healthy level (e.g., 98.5%). However, during a surgical procedure, the patient's metabolic rate may decrease. This, in turn, means that the blood needs to be exposed to less oxygen in the oxygenator to achieve the same blood oxygen saturation. This decrease in metabolic rate may be detected in the form of an increase in the patient's blood oxygen saturation caused by the continued supply of the first and second oxygenated gases 642a, 642b at the same oxygen concentration and flow rate despite the decreased metabolic rate. This may be detected, for example, by a sensor. In such a case, the system may transition to state (c), as indicated by arrow 662.

[0145] In state (c), the flow rate of the second oxygenated gas 642b is reduced. This reduces the amount of second oxygenated gas 642b present at the second interface region 640b at a given time. This reduces the amount of oxygen the blood is exposed to, leading to a decrease in the patient's blood oxygen saturation. The oxygen saturation may return to the target oxygen saturation (e.g., 98.5%) with a lower flow rate of the second oxygenated gas 642b. Alternatively, the flow rate of the second oxygenated gas 642b may need to be reduced to zero (so that no oxygenated gas is present at the second interface region 640b) before the target oxygen saturation is achieved. In some instances, this reduction to zero may not be sufficient to achieve the target oxygen saturation. Therefore, the system may transition to state (d), as indicated by arrow 664, to continue reducing the amount of oxygen the blood is exposed to (e.g., in response to the flow rate of the second oxygenated gas 642b being reduced to zero).

[0146] In state (d), there is no supply of oxygenated gas to the second interface region 640b. The oxygen concentration in the first oxygenated gas 642a may be reduced to further reduce the amount of oxygen to which the blood is exposed. This further reduces the amount of oxygen in the oxygenator 600, allowing the oxygen saturation to be further reduced until a target oxygen saturation is reached. Advantageously, this allows the system to effectively manage oxygen saturation in a patient experiencing a low metabolic rate (e.g., a patient undergoing circulatory arrest). As the patient returns to a high (e.g., normal) metabolic rate, the FiO2 of the first oxygenated gas 642a can again be increased to increase the amount of oxygen present in the oxygenator 600. The FiO2 may continue to be increased until it reaches 100%. The system thereby returns to state (a), as indicated by arrow 666.

[0147] It will be appreciated that Figure 6 represents a specific example of the operation of the system described herein in a patient who initially has a normal metabolic rate and then has a low metabolic rate. In practice, as the patient's metabolic rate may increase or decrease during a surgical procedure, the system may freely move between all of the states in Figure 6. That is, the system is not simply limited to the sequence depicted, but instead may increase or decrease the concentration and / or flow rate of the first and / or second oxygenated gas as needed to achieve a target oxygen saturation (or other physiological parameter).

[0148] It will be understood that any feature, function, characteristic, or advantage described with respect to the system example above may also be applied to the method example above, and vice versa. Similarly, any feature, function, characteristic, or advantage described with respect to the oxygenator example above may also be applied to any of the system or method example above.

[0149] According to the present disclosure, the following aspects are also contemplated.

[0150] Aspect 1. A method of controlling blood oxygenation of a patient with an artificial lung, the artificial lung configured to receive blood from the patient and expose the blood to a constant amount of oxygen as the blood passes through the artificial lung to produce oxygenated blood; The method comprises: measuring the oxygen saturation present in the oxygenated blood downstream of the oxygenator; calculating a difference between a target oxygen saturation and the measured oxygen saturation; adjusting the amount of oxygen the blood is exposed to in the oxygenator to reduce the difference; A method comprising:

[0151] Aspect 2. The method of aspect 1, wherein the oxygen saturation present in the oxygenated blood is measured on a blood line, the blood line being connected to the oxygenator and configured to carry oxygenated blood from the oxygenator to the patient.

[0152] Aspect 3. The method of Aspect 2, wherein measuring the oxygen saturation comprises performing spectrophotometry on the oxygenated blood in the blood line.

[0153] Aspect 4. The method of any one of Aspects 1 to 3, wherein adjusting the amount of oxygen comprises adjusting the oxygen concentration in the oxygenated gas received by the oxygenator.

[0154] Embodiment 5. The method of any one of embodiments 1 to 5, wherein the oxygenated gas consists of pure oxygen.

[0155] Aspect 6. The method of any one of Aspects 1 to 5, wherein the artificial lung includes a gas-blood interface through which oxygenated gas is supplied to expose the blood to the constant amount of oxygen, and adjusting the amount of oxygen includes adjusting the proportion of the gas-blood interface through which the oxygenated gas is supplied.

[0156] Aspect 7. The method of Aspect 6, wherein the gas-blood interface comprises a plurality of interface regions each configured to be independently supplied by a respective oxygenated gas, and wherein adjusting the proportion of the gas-blood interface supplied with oxygenated gas comprises varying the number of interface regions supplied with oxygenated gas.

[0157] Aspect 8. The method of any one of Aspects 1 to 7, wherein the oxygenator includes a gas-blood interface configured to receive an oxygenated gas to expose the blood to the amount of oxygen, the gas-blood interface including a first interface region configured to receive a first oxygenated gas and a second interface region configured to receive a second oxygenated gas, the first interface region and the second interface region collectively comprising the entire gas-blood interface.

[0158] Aspect 9. Adjusting the amount of oxygen to which the blood is exposed comprises: first supplying the first oxygenated gas only to the first interface region without supplying the second oxygenated gas to the second interface region; adjusting the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate of the first oxygenated gas; thereafter, commencing delivery of the second oxygenated gas to the second interface region of the gas-blood interface to increase the amount of oxygen to which the blood is exposed. The method of embodiment 8, further comprising:

[0159] Aspect 10. The method of claim 9, wherein initiating the supply of the second oxygenated gas is in response to an increase in the oxygen concentration in the first oxygenated gas to a threshold concentration.

[0160] Aspect 11. Adjusting the amount of oxygen to which the blood is exposed comprises: supplying the first oxygenated gas to the first interface region and the second oxygenated gas to the second interface region; adjusting the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate of the second oxygenated gas; 11. The method of any one of embodiments 8 to 10, comprising:

[0161] Embodiment 12. The method of embodiment 11, wherein adjusting the amount of oxygen to which the blood is exposed comprises reducing the oxygen concentration in the first oxygenated gas in response to the flow rate of the second oxygenated gas being reduced to a threshold flow rate.

[0162] Aspect 13. The target oxygen saturation is a first target oxygen saturation; The method further comprises: in response to measuring an oxygen saturation level equal to the first target oxygen saturation level, to achieve a second target oxygen saturation level; i) increasing the oxygen concentration and / or flow rate of said first oxygenated gas, and / or ii) starting the supply of said second oxygenated gas; Including, 13. The method of any one of embodiments 8 to 12, wherein the second target oxygen saturation is higher than the first target oxygen saturation.

[0163] Embodiment 14 The method of any one of embodiments 8 to 13, further comprising further adjusting the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate of the second oxygenated gas.

[0164] Embodiment 15. The method further comprises: decreasing the flow rate of the second oxygenated gas in response to measuring an oxygen saturation greater than the target oxygen saturation; decreasing the oxygen concentration in the first oxygenated gas after decreasing the flow rate and in response to the sensor measuring an oxygen saturation that remains greater than the target oxygen saturation. 15. The method of any one of embodiments 8 to 14, comprising:

Claims

1. 1. A system for controlling blood oxygenation of a patient, comprising: an oxygenator configured to receive blood from the patient, the oxygenator configured to expose the blood to a quantity of oxygen as the blood passes through the oxygenator to produce oxygenated blood; a sensor disposed downstream of the oxygenator and configured to measure oxygen saturation present in the oxygenated blood; Controller and Including, The controller receiving the measured oxygen saturation from the sensor; calculating a difference between a target oxygen saturation and the measured oxygen saturation; adjusting the amount of oxygen to which the blood is exposed in the oxygenator to reduce the difference; A system configured to:

2. 10. The system of claim 1, wherein the sensor is disposed on a blood line, the blood line being configured to connect to the oxygenator and carry the oxygenated blood from the oxygenator to the patient.

3. The system of claim 2 , wherein the sensor is configured to measure the oxygen saturation present in the oxygenated blood via spectrophotometry performed on the blood line.

4. 4. The system of claim 1, wherein the controller is configured to adjust the amount of oxygen by adjusting the oxygen concentration in the oxygenated gas received by the oxygenator.

5. 5. The system of claim 1, wherein the controller is configured to adjust the amount of oxygen by adjusting the flow rate of oxygenated gas received by the oxygenator.

6. 6. The system of claim 1, wherein the oxygenated gas consists of pure oxygen.

7. 7. The system of claim 1, wherein the oxygenator includes a gas-blood interface configured to deliver an oxygenated gas to expose the blood to the amount of oxygen, and the controller is configured to adjust the amount of oxygen by adjusting the proportion of the gas-blood interface to which the oxygenated gas is delivered.

8. 8. The system of claim 7, wherein the gas-blood interface includes a plurality of interface areas each configured to be independently supplied with a respective oxygenated gas, and the controller is configured to adjust the proportion of the gas-blood interface supplied with the oxygenated gas by varying the number of interface areas supplied with the oxygenated gas.

9. 9. The system of claim 8, wherein the oxygenator includes a gas inlet zone for receiving oxygenated gas to the gas-blood interface, the gas inlet zone including one or more partitions dividing the gas inlet zone into a plurality of gas inlet regions, each gas inlet region configured to receive oxygenated gas from a different one of the respective oxygenated gases and provide the respective oxygenated gas to a respective one of the interface regions.

10. 10. The system of claim 1, wherein the oxygenator includes a gas-blood interface configured to receive an oxygenated gas to expose the blood to the amount of oxygen, the gas-blood interface including a first interface region configured to receive a first oxygenated gas and a second interface region configured to receive a second oxygenated gas, the first interface region and the second interface region collectively comprising the entire gas-blood interface.

11. The controller controls the amount of oxygen to which the blood is exposed. first supplying the first oxygenated gas only to the first interface region without supplying the second oxygenated gas to the second interface region; adjusting the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate of the first oxygenated gas; thereafter, commencing delivery of the second oxygenated gas to the second interface region to increase the amount of oxygen to which the blood is exposed; The system of claim 10 configured to adjust by:

12. 12. The system of claim 11, wherein the controller is configured to initiate delivery of the second oxygenated gas in response to an increase in oxygen concentration in the first oxygenated gas to a threshold concentration.

13. The controller controls the amount of oxygen to which the blood is exposed. supplying the first oxygenated gas to the first interface region and the second oxygenated gas to the second interface region; adjusting the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate of the second oxygenated gas; 13. The system of claim 10, configured to regulate by:

14. 14. The system of claim 13, wherein the controller is further configured to adjust the amount of oxygen to which the blood is exposed by reducing the oxygen concentration in the first oxygenated gas in response to the flow rate of the second oxygenated gas being reduced to a threshold flow rate.

15. the target oxygen saturation is a first target oxygen saturation; The controller further comprises: in response to the sensor measuring an oxygen saturation level equal to the first target oxygen saturation level, to achieve a second target oxygen saturation level; i) increasing the oxygen concentration and / or flow rate of the first oxygenated gas; and / or ii) starting the supply of the second oxygenated gas; Including, The system of claim 10 , wherein the second target oxygen saturation is higher than the first target oxygen saturation.

16. 16. The system of any one of claims 10 to 15, wherein the controller is configured to further adjust the amount of oxygen to which the blood is exposed by adjusting the oxygen concentration and / or flow rate of the second oxygenated gas.

17. The controller further comprises: decreasing the flow rate of the second oxygenated gas in response to the sensor measuring an oxygen saturation greater than the target oxygen saturation; 15. The system of claim 10, wherein the system is configured to: reduce the oxygen concentration in the first oxygenated gas after reducing the flow rate and in response to the sensor measuring an oxygen saturation that remains greater than the target oxygen saturation.

18. a venous reservoir configured to receive blood from the patient; a pump configured to drive blood flow from the venous reservoir through the oxygenator; and 18. The system of claim 1, further comprising:

Images