A device for dynamic assessment of blood loss in the early postpartum period

Abstract

This utility model pertains to the field of medicine, specifically obstetrics, and can be used for dynamically assessing the volume of blood loss in the early postpartum period. The device is a device for dynamically assessing the volume of blood loss in the early postpartum period. It is designed as a two-lever mechanism integrated into a two-section obstetric bed, the levers of which are the seat and backrest. It consists of three main elements: a fixed support platform with a built-in strain gauge, digital indicator, and power source; a movable seat (first lever) with a single support point on the platform; and a movable backrest (second lever) with a roller support at the apex and a common point of force application, connected to the seat via a hinge mechanism. The backrest of the device can be tilted parallel to the backrest of the obstetric bed, and a rotary seat lock and a goniometer are provided to control the tilt angle.The supporting elements of the platform, seat, and backrest are made of 20 mm thick cold-pressed birch plywood, the contact surfaces are covered with polyurethane foam (50 mm, density 22 kg / m³) and vinyl leather. The fastening units, hinges, locking eccentrics, rollers, and goniometers are made using additive technology (3D printing) from polylactide, the hinge axes and load-bearing elements are made of low-carbon steel. A load cell (range 0-200 kg, accuracy class C3) is installed at the common point of application of the lever force. Overall dimensions: platform and seat 650 × 340 mm, backrest 820 × 600 mm. The digital LED indicator provides a display accuracy of 0.01% FS, powered by a network AC / DC converter (220 V → 24 V, 60 W). The protractors provide step-by-step adjustment of the backrest angle from 0° to 55° in 5° increments. All electronic components and housings comply with IP65 protection and CE / RoHS standards.

Description

[0001] The utility model relates to the field of medicine, namely obstetrics, and can be used for dynamic assessment of the volume of blood loss in the early postpartum period.

[0002] Postpartum hemorrhage is a leading cause of maternal morbidity and mortality worldwide, affecting up to 10% of all births. Most deaths due to postpartum hemorrhage occur within the first 24 hours (early postpartum period) [1]. According to current clinical guidelines, visual assessment of blood loss during childbirth is associated with an underestimation of 30-50% [1, 2]. An objective method is considered to be gravimetric (weighing) using graduated containers and measuring the mass of blood-soaked materials [2]. However, existing solutions require the involvement of medical personnel to transfer materials to scales, interrupt the observation process, create a risk of contamination, and do not provide continuous recording of blood loss dynamics in the context of active management of the early postpartum period.

[0003] A device is known for dynamically assessing the volume of blood loss in the early postpartum period, which is a collection bag consisting of pads on the shins and thighs, a support frame that ensures the tightness of the bag opening, an internal bag for collecting amniotic fluid, an external bag for collecting blood, a scale for assessing the volume of amniotic fluid and blood in 100.0 ml increments, and a drain valve for evacuating the contents of the bag with blood [3].

[0004] The device has a number of disadvantages:

[0005] 1. Insufficient accuracy due to the fact that the scale step for measuring the volume of blood loss is 100.0 ml, the device collects only freely flowing blood and does not take into account the volume absorbed by the adsorbent material used during medical care, and the researcher's viewing angle affects the visual assessment of the blood level corresponding to the scale value of the collection bag.

[0006] A device for gravimetrically assessing the volume of blood loss is known, consisting of a medical electronic scale for weighing blood-soaked materials. The electronic medical scale consists of a control unit and a weighing module comprising a housing, a base, a weighing platform with mounting points, and a measuring device located between them and designed as two upper load arms with strain gauges [4].

[0007] The device has the following disadvantages:

[0008] 1. Insufficient accuracy due to the fact that only the weight of materials soaked with blood is taken into account, and the volume of lost blood not absorbed by the absorbent material, as well as the volume of blood loss during the birth of the placenta, are not taken into account.

[0009] 2. Complexity of use due to the need for additional technical steps, such as collecting, sorting, and transferring blood-soaked materials to the measuring device.

[0010] A device for dynamically assessing blood loss volume is known, taken as a prototype. It consists of a bed with a support frame and a weighing frame, on which load cells are mounted. The readings from the sensors are summed to obtain the total weight on the weighing frame. The patient's weight is subtracted from the tare weight. The weighing frame, with its patient support surface, is attached to the bed's support frame via four load cells located at the corners. The sensor signals are summed to determine the total weight, from which the tare weight is subtracted [5].

[0011] The device has the following disadvantages:

[0012] 1. Insufficient accuracy due to the fact that artifacts of the patient's movements (contractions, pushing, changes in position) can lead to an increase in measurement error.

[0013] 2. The limited use of the device in obstetric practice, since the process of delivery in most cases requires the lithotomy position of the patient [6].

[0014] To improve accuracy and optimize the use of the device in obstetric practice, a special device has been developed that allows an obstetrician-gynecologist to analyze the volume of blood loss in the early postpartum period dynamically with high accuracy.

[0015] The device is designed as a two-lever weight measurement mechanism integrated into a two-section obstetric bed. The levers in this mechanism are the seat and backrest of the device, where the backrest of the device can be tilted parallel to the backrest of the obstetric bed. The device consists of three main elements: a fixed support platform with a built-in load cell, a digital load cell indicator, and a DC power source; a movable seat, which functions as the first lever, having one fulcrum with the support platform and a common point of force application together with the backrest; a movable backrest, which functions as the second lever, having one fulcrum, made in the form of a roller located at the top of the backrest, as well as a common point of force application with the seat, connected by a hinge mechanism. The device is equipped with a rotary mechanism for locking the mobility of the seat and a goniometer for measuring the deflection of the backrest.

[0016] The base of the support platform, seat, and backrest are made of 20mm thick cold-pressed birch plywood. The seat and backrest are covered on the contact surface with 50mm thick polyurethane foam with a density of 22 kg / m3. 3 and vinyl leather. The support platform measures 650 x 340 mm, the seat measures 650 x 340 mm, and the backrest measures 820 x 600 mm. The load cell and weight indicator mounting elements, the roller with support, the rotary mechanism handle, the seat locking eccentrics, the protractors, and the hinge mechanism connecting the fixed support platform to the seat are manufactured using additive manufacturing technology using 3D printing from polylactide. The hinge mechanism axes, the rotary locking mechanism, and the hinge mechanism connecting the seat and backrest force application points are made of mild steel.

[0017] The load cell is installed in the support platform at the common point of application of the force of the seat and backrest levers of the device. The load cell is factory-made and has a weight measurement range of 0 to 200 kg. Accuracy class C3. CE, RoHS certification. Sensitivity 0.5-2.0 mV / V, delay error ≤0.3% FS, nonlinearity ≤0.5% FS, repeatability error ±0.3 FS, temperature effect on sensitivity ±0.1% FS, input resistance 350 ± 30 Ω, output resistance 350 ± 5 Ω, insulation resistance> 5000 MΩ, reference voltage 5-24 V, operating temperature range -20 ~ 80, protection level IP65.

[0018] The load cell indicator is installed in the space between the support platform and the movable seat. The indicator is factory-made and has a display range of -19999~99999 on a 5-digit, 7-segment LED display, an accuracy of 0.01% FS, 24-bit DAC and ADC, an operating temperature of -10~60°C, a zero drift of no more than ±0.5 μV / °C, a reference voltage of 5-24 V, and is equipped with auto-zeroing and operating mode setting keys. The indicator has an IP65 protection level and is CE and RoHS certified.

[0019] The DC power supply is installed in the space between the support platform and the movable seat and is a factory-made AC / DC voltage converter. The converter has an input voltage of 220 V (AC 50 / 60 Hz), an output voltage of 24 V (DC), an error of ±5%, a power of 60 W, an operating temperature of 0~60 °C, CE and RoHS certification, and an IP65 protection level.

[0020] The protractor for measuring the backrest tilt is installed at the junction point of the hinge joint of the seat and backrest on two opposite sides, made by 3D printing from polylactide, and has a measuring range of 0~55° with a measuring increment of 5°.

[0021] The design of the device is explained in Fig. 1 and 2.

[0022] In Fig. 1, the main design elements of the device are indicated by numbers 1-3 (isometric view):

[0023] 1. Fixed support platform;

[0024] 2. A movable seat that functions as the first lever;

[0025] 3. Movable backrest that functions as a second lever.

[0026] In Fig. 2, numbers 4-9 indicate auxiliary elements of the structure (isometric view; element of Fig. 1, the movable seat, is hidden):

[0027] 4. Digital load cell indicator;

[0028] 5. DC power supply;

[0029] 6. Load cell;

[0030] 7. Roller with support;

[0031] 8. Angle meter;

[0032] 9. Seat locking mechanism rotary handle.

[0033] The operating principle of the device is explained in Fig. 3 and 4 (side view):

[0034] Fig. 3 shows the device in the weight measurement mode with the backrest in a horizontal position (0° position). Fig. 4 shows the device in the weight measurement mode with the backrest in the maximum tilt position (55° position).

[0035] The technical result is the creation of a device that is a lever-measuring mechanism designed for dynamic assessment of the volume of blood loss in the early postpartum period.

[0036] The dynamic blood loss assessment process using the developed device is carried out in stages. Initially (after the birth of the baby and the rupture of the posterior amniotic fluid), the device, on which the patient can remain positioned throughout labor, must be set to weight measurement mode with the backrest horizontal (0° position). Next, turn on the DC power source, activate the load cell indicator, turn the locking mechanism counterclockwise, and press the auto-zero button. The woman's weight is then monitored on the display. To determine the volume of blood loss in the early postpartum period, the placenta weight and urine volume are subtracted from the display value, and the volume of infusion therapy administered at a specific point in time is then added to this value.The developed device then dynamically assesses the volume of blood loss before the patient is transferred to the postpartum ward or other departments of the maternity hospital. Before transporting the patient, the rotary locking mechanism is turned clockwise, and the load cell indicator and DC power source are turned off.

[0037] Specific example of using the device

[0038] Patient N., 29, a multiparous woman, was admitted to the maternity ward in the first stage of labor at 39 weeks and 2 days of gestation. After obtaining written, voluntary, informed consent for the use of the developed technical solution, the patient remained on the developed device, integrated into the obstetric bed, for the entire observation period. The delivery was vaginal. A live, full-term boy was born, weighing 4180 g and measuring 54 cm in length, with an Apgar score of 8 and 9. The total duration of labor was 5 hours 20 minutes, with an anhydrous period of 35 minutes.

[0039] The dynamic blood loss assessment process using the developed device was carried out in stages. Initially, after the birth of the baby and the rupture of the posterior amniotic fluid, the device was switched to weight measurement mode with the backrest in a horizontal position (0° position). Next, the DC power source was turned on, the load cell indicator was activated, the rotary locking mechanism was turned counterclockwise, and the auto-zero button was pressed. After the display reached zero, continuous assessment of the woman's weight dynamics began.

[0040] Early postpartum hypotonic bleeding developed in the early postpartum period: uterine tone was decreased, the fundal height was 2 cm above the umbilicus, and active discharge of bright red blood with clots was observed from the birth canal. The device display recorded a decrease in weight. To determine the volume of blood loss in the early postpartum period, the placenta weight (0.490 kg) and the volume of urine excreted (0.010 L) were subtracted from the display value, then the volume of infusion therapy administered at a specific point in time (0.300 L) was added to the resulting value. The estimated blood loss was 0.500 kg (500 ml) in the first 15 minutes, which met the criteria for pathological blood loss according to current clinical guidelines. The obtained objective data allowed for a timely initiation of an action plan aimed at treating early postpartum hypotonic bleeding.By the 25th minute, the display showed stabilization of the mass value, which confirmed the effectiveness of the hemostatic measures taken.

[0041] Before transporting the patient, the rotary locking mechanism was turned clockwise, the load cell indicator and the DC power supply were turned off. The patient was transferred in satisfactory condition. The postpartum period was uneventful. The patient was discharged on the fifth day in satisfactory condition.

[0042] To develop an optimal device design to improve accuracy and simplify the process of dynamically assessing blood loss volume in the early postpartum period, the S2200 VICTORIA childbirth and clinical skills simulator for maternal care was initially used. Validation tests were conducted by simulating 100 clinical scenarios of early postpartum blood loss by placing a reservoir with a variable volume from 150 to 3600 ml in a cavity along the body of the S2200 VICTORIA model, covering the entire diagnostic spectrum: from physiological losses to critical massive blood loss with the development of hemorrhagic shock. The results were evaluated by comparing the readings of the developed device with the absolute values ​​of the simulated blood loss. The relative error of the developed device was 5.7 (3.6; 8.5)%.

[0043] Conclusion: The use of the developed device for dynamic assessment of the volume of blood loss in the early postpartum period allows us to simplify the process and increase the accuracy of measurements, which will optimize the tactics of patient management in the development of early postpartum hemorrhage.

[0044] Bibliography

[0045] 1. Clinical guidelines "Postpartum hemorrhage" - (2025): [approved by the Ministry of Health of the Russian Federation]. URL: https: / / cr.minzdrav.gov.ru /

[0046] 2. Clinical recommendations “Prevention, management algorithm, anesthesia and intensive care for postpartum hemorrhage” (letter of the Ministry of Health of the Russian Federation dated March 26, 2019 No. 15-4 / i / 2-2535).

[0047] 3. Wang F. Measurement of postpartum blood loss using a new two-set liquid collection bag for vaginal delivery: A prospective, randomized, case control study / Wang F., Lu N., Weng X., Tian Y., Sun S., Li B. / / Medicine (Baltimore). - 2021. - Vol. 100, N. 14. - 25906. DOI: 10.1097 / MD.0000000000025906.

[0048] 4. Patent for utility model No. 19159 Russian Federation, IPC G01G 3 / 12 (2000.01); A61G 11 / 00 (2000.01). Electronic medical scales: No. 2000122549 / 20; declared 01.09.2000; published 10.08.2001 / Novikov Yu.S., Sitdikov F.G.; applicant and patent holder: AOZT PTP "Resonance". - Bulletin No. 22. - 13 p.: ill.

[0049] 5. U.S. Patent No. 4,953,244, IPC A61G 7 / 00; A61G 19 / 59. Hospital bed for weighing patients: U.S. Pat. No. 138,829; filed 12 / 28 / 1987; published 09 / 04 / 1990 / Koerber CJ Sr., Boyd HJ; applicant and patent holder: Hill-Rom Company, Inc. - 14 pp.: 3 ill.

[0050] 6. Clinical guidelines "Normal childbirth (singleton birth, spontaneous delivery in the occipital presentation)" - (2024): [approved by the Ministry of Health of the Russian Federation]. URL: https: / / cr.minzdrav.gov.ru /

Claims

A device for dynamically assessing the volume of blood loss in the early postpartum period, including a support platform with a built-in strain gauge, a digital indicator and a power source, characterized in that the platform is integrated into the base of a two-section obstetric bed and is connected to a two-lever mechanism, the levers in which are a movable seat and a movable backrest, wherein the seat is made with one support point on the platform, the backrest is made with a roller support at the top and a common point of application of force, connected to the seat by means of a hinge mechanism in which a strain gauge is installed, and the backrest is equipped with a goniometer that provides stepwise fixation of the angle of inclination in the range of 0 ° - 55 ° in 5 ° increments, and a rotary lock of the seat mobility, the digital indicator is made with the function of automatic zeroing after fixing the position of the patient and continuous dynamic recording of the change in the patient's weight, and the fastening units, hinges, locking eccentrics,The rollers and angle gauges are made using additive technology from polylactide, the hinge axes and power elements are made of low-carbon steel, the supporting elements of the platform, seats and backrests are made of 20 mm thick cold-pressed birch plywood, the contact surfaces are covered with 50 mm thick polyurethane foam with a density of 22 kg / m³ and vinyl leather, the load cell has a range of 0-200 kg and accuracy class C3, the digital LED indicator provides a display accuracy of 0.01% FS and is connected to a network AC / DC converter with an input voltage of 220 V and an output voltage of 24 V, a power of 60 W, all electronic and housing components comply with IP65 protection level and CE / RoHS standards.

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