Repositioning device

Abstract

An inflatable prone repositioning device is provided and comprises a multi-chamber inflatable pillow positionable underneath a proned patient and which can be inflated to raise a patient's chest and h

Description

The present invention relates generally to patient care and particularly, although not exclusively, to a repositioning device for patients requiring respiratory support. Respiratory support is one of the most common reasons for patients to be admitted to the Intensive Care Unit (ICU). Approximately 235,000 patients per year are admitted to ICUs in the UK1. Evidence suggests that over 16,500 of these (7%)2 have lung injury of such significant severity that “proning” will be beneficial. Proning describes the technique whereby sedated, ventilated patients are turned on their front. Once proned, patients stay on their front for 16-18 hours. Depending upon the patient’s condition, this process may be repeated multiple times during an ICU stay. Proning improves oxygen levels and improves survival in patients who are severely oxygen dependent on ICU6'7. With a reduction in the absolute risk of death by 17.4%4, proning represents the single most beneficial intervention that can be afforded to patients who are severely oxygen dependent on ICU. As such, the technique forms part of national guidance for ICU clinicians in the UK10. However, the complications associated with the technique are well recognised910. To mitigate the risk of complications, national guidance recommends that whilst proned a patient’s head needs to be turned and their arms repositioned every 2-4 hours to minimise pressure sores and nerve injuries3. This labour-intensive process requires a team of 5+ staff and takes 20-60 minutes to perform (more if full PPE is required). Repositioning is currently carried out in one of three ways: 1. The patient is slid up the bed to allow their head (now clear of the mattress) to be rotated before returning to the original position. 2. A hoist can be used to lift the patient off the bed, allowing repositioning whilst elevated. The hoist is a large device which are typically limited in number and can be difficult to manoeuvre. This approach requires regular insertion / removal of slings and movement of the patient can be unpredictable. 3. A specialist proning bed can be used, but this is prohibitively expensive (£800+ per day), complicated and requires large areas when not in use. During repositioning, the greatest risk is the inadvertent removal, blockage or displacement of patient support systems (on which the patient’s life is continuously dependent). This is particularly true with method 1, the commonest technique used in the UK. All techniques also require the patient’s chest and pelvis to rest on pillows, which if moved during repositioning, can damage organs such as the eyes, liver, pancreas or genitals. All three repositioning methods also require five or more staff members. At the height of the COVID-19 pandemic, dedicated teams were formed to perform proning and head turns on patients. These teams are no longer available, and the process of head turning must now be undertaken with the limited number of busy staff available on the ICU. Staff shortages on ICU in the post-pandemic era are more significant than they were pre-pandemic, making liberating staff to perform head turns more challenging than ever before3. Liberation of staff time and staff cost is vital in ICU because: - Staff shortages on ICU remain a continual and pressing concern in the post-pandemic era3. Staff shortages impact the number of patients that can be cared for in ICU and the quality of care. - Staff burnout remains an ongoing challenge on ICU5, deepening the staffing crisis. Greater awareness of the benefits of proning, mean that the threshold for this technique is lower in the post-pandemic era. This increased use, in combination with the demanding and far from risk free repositioning process (and a general desire for reduction in manual handling injuries), means there is a need to explore safer and more efficient repositioning techniques. The present invention seeks to provide improvements in or relating to patient repositioning. Aspects and embodiments of the present invention may have one or more of the following goals: 1. Allow repositioning of the head and arms whilst perceptively reducing the risk of line and tube blockage, or displacement and personal injuries. 2. Reliably reduce the number of staff required in the full range of patient height / weights in ICU. 3. Reduce manual handling and the time it takes for repositioning. Some embodiments provide an Inflatable Prone Repositioning Device (IPRD). Some embodiments provide an IPRD that improves the safety of repositioning proned patients and reduces the number of staff and the time required. In some embodiments a device is provided as an inflatable pillow that can be placed under a patient while proned and inflated to allow them to be repositioned in a controlled fashion and / or to allow them to maintain a more anatomical position. Embodiments of the present invention may use controllable inflatable vessels to enable a patient to be positioned or repositioned. An aspect of the present invention provides an inflatable prone repositioning deviceprovided as a bag or pillow, the device has only three vessels, the three vessels can be individually inflated and deflated, the bag is positionable underneath a proned patient, the bag or pillow is configured for use with the three vessels extending generally orthogonal to the length of a patient, whereby, in use, vessels can be selectively inflated to raise a patient’s chest and hips to provide clearance for turning of the patient’s head . In some embodiments the chambers can be individually inflated and deflated. In other embodiments the chambers can be inflated together to a maximum extent. In some embodiments a control system may be provided. The control system may, for example, allow a preset inflation or deflation sequence to be initiated. In some embodiments the device assumes or can assume a generally wedge-like configuration. For example, at least one of the vessels may have a predetermined and / or maximally inflated height different to other vessels, whereby the device can assume a wedge-like configuration. In aspects and embodiments of the present invention a quick release mechanism for rapid deflation may be provided. For example a quick release pull-tab may be provided for rapid deflation if CPR is required. Some embodiments may be provided as disposable / single patient use vessels. In some embodiments the geometry of the device may be configured to prevent wrinkling upon deflation. Some embodiments may be provided with a line indicating shoulder height on the vessels. Some embodiments may comprise anti-slip means to prevent slippage. Anti-slip feature may, for example, be provided underneath the vessels to prevent slippage, for example rubber strips. In aspects and embodiments of the present invention a quick release mechanism for rapid deflation may be provided. For example a quick release pull-tab may be provided for rapid deflation if CPR is required. Some embodiments may be provided as disposable / single patient use vessels. In some embodiments the geometry of the device may be configured to prevent wrinkling upon deflation. Some embodiments may be provided with a line indicating shoulder height on the vessels. Some embodiments may comprise anti-slip means to prevent slippage. Anti-slip feature may, for example, be provided underneath the vessels to prevent slippage, for example rubber strips. In some embodiments pressure sensing means is provided, for example to monitor and avoid / prevent overinflation. In some embodiments a pressure relief system is provided, such as a pressure relief valve to prevent overinflation. Some devices further comprise a pressure relief layer. The pressure relief layer may comprise a secondary layer on the top of the vessels to reduce pressure sores over long term inflation of the device underneath patients. Some embodiments may include the addition of a secondary layer on the top of the vessels to reduce pressure sores over long-term inflation of the device underneath patients. Some embodiments may include pressure sensors (e.g. inside and / or on the device) to identify potential “hot spots” (areas of higher pressure on the skin) that could lead to pressure sores. A feedback system may be provided to take account of areas identified as applying too much pressure and to take remedial action (e.g. by inflating / deflating a vessel, or one or more chambers of a multi-chamber vessel). This opens up the potential for mapping of skin pressure of the patients to understand high pressure locations and improve care of patients. The intended use of some embodiments is for proned patients while intubated and ventilated to allow bespoke repositioning and for a small number of staff to reposition a patient. In some embodiments an IPRD comprises a multi-vessel inflatable pillow placeable underneath a proned patient and which can be inflated by use of a controller to raise the patient’s chest and hips. With the patient raised, repositioning of the head and arms can occur with ease before the device is returned to the resting position. Some embodiments provided a bag / pad / pillow / cushion that can be positioned under the chest region of a patient and includes multiple (e.g. three or more) chambers (e.g. heat sealed vessels) that extend laterally and are separately / independently inflatable / deflatable for the particular purpose of head turning of a proned patient. A further aspect provides a proning inflation device using air-pressure chambers to lift a patient’s torso, freeing the head from the mattress and enabling the manual turning of their head. This removes the need for manual patient lifting, provides significantly more control (and thereby safety) and reduces the staff and time required. It may also reduce the risk of manual handling injuries to staff (which currently account for 15% of all NHS absences). A bariatric version may be provided: a wider version suitable for a larger maximum patient weight. A paediatric version may be provided: a smaller version suitable for children. This may require adjustment capability to adapt to a variety of sizes. For use of devices in operating theatres: the device may require adaptations to allow for use in theatre, such as removal of any metallic components. Some embodiments are pneumatically operated. For example, compressed air may be driven into vessel / s and / or a vacuum may be generated to suck air out. Some embodiments are provided as a single “bag” or "mat" that is internally divided (e.g. heat sealed) into multiple vessels. In other embodiments multiple separate vessels may be provided; in this case a “overbag” may be provided to house the vessels together. Some embodiments may be configured to allow a subject to be moved to bespoke positions. A further aspect provides a system for proned patient repositioning, the system comprising a plurality of inflatable, flexible vessels to lift a patient from their torso, allowing their head to be turned manually, and a controller for selectively inflating or deflating the vessel. In some embodiments the controller can provide a predetermined automated inflation and / or deflation sequence of the vessels. In some embodiments the controller can provide an automated repetitive inflation I deflation cycle. The automation of a repetitive inflation / deflation exercise could further alleviate pressure sores. A further aspect provides a method of repositioning a proned patient comprising the steps of: using air-pressure chambers to lift a patient’s torso, freeing their head from a bed; manually turning the patient’s head; and lowering the head. The method may be performed using a device or a system as described herein. A further aspect provides an inflatable prone repositioning device comprising an inflatable pillow positionable underneath a proned patient in a deflated form and which can be inflated to a wedge-like inflated form to raise a patient’s torso such that with the patient raised, repositioning of the head can occur before the device is returned to a deflated form. The device may be provided as a single inflatable chamber with a predetermined wedge-like form. The device may be provided as multiple inflatable chambers (provided separately or as part of a single unit) which together can assume a wedge-like form. In some aspects and embodiments, where multiple chambers are provided, each chamber may be substantially the same or similar, in terms of shape and / or size and / or maximal inflation extent. In other embodiments one or more features of a chamber / s may be different from other chamber / s. In some embodiments the device is configured / adapted / intended for use with chamber / s extending laterally i.e. generally orthogonal to the length of a patient. A further aspect of the present invention provides or relates to a pressure sensing array to be used with an Inflation Proning Repositioning Device (IPRD). The IPRD is an inflatable vessel which aids healthcare workers in repositioning, for example, intubated patients with Acute Respiratory Distress Syndrome (ARDS) in the prone position by reducing the number of healthcare professionals and time required for repositioning. Currently, manual repositioning is not done regularly enough to prevent pressure ulcer formation in some cases, a problem which can be improved by using the IPRD, but this could be further improved by incorporating pressure data feedback. This could inform doctors where pressure points are for more effective repositioning, or optionally through automated closed- loop control of the IPRD vessel pneumatics to constantly reposition the patient to avoid pressure ulcers forming. Pressure ulcers are one of the biggest sources of litigation against the NHS and treatment costs an estimated £1.4 - £2.1 billion annually in the UK. Embodiments may provide the ability to map surface pressure distribution across the IPRD to help mitigate the formation of pressure ulcers, which form because patients with ARDS are unable to move themselves while proned. Pressure mapping capabilities may be integrated with the IPRD to provide live pressure location data. A sensor architecture may be provided which is flexible, thin, and does not introduce hard lumps or sources of pressure concentrations, while also having a good enough resolution to detect pressure point locations. Example Features • Unobtrusive design: The pressure sensor cannot contain any rigid objects or components that would potentially introduce pressure points. • Flexible surface: The IPRD is an air vessel that will inflate and deflate with the pressure sensor array between it and the patient. The sensor array should conform to the IPRD surface as much as possible. • Sterilisable: Ultimately the pressure sensor may be used with ICU patients. It is completely unsustainable to make the sensor array single-use so there may be considerations allowing sterilisation / protection for reuse. Example Pressure Sensor Array: - Minimum sensor array resolution: 0.125 cells / cm2 (80 mm spacing) - Sensor array covers IPRD (850 x 500 mm) - Sensor array is thin, flexible, and bendable - No hard objects or pressure points introduced to IPRD surface Example Measurement Scanning Electronics: - Minimum sensor array sample rate 0.3 Hz - Sensitive to ±5 mmHg (0.6 kPa) A pressure sensor matrix / array may be provided. Piezoresistive and / or capacitive sensors may be used. Some embodiments comprise a thin, flexible piezoresistive-based pressure sensor array. Some embodiments provided a separate mat / layer which is attached or associated with an inflation vessel. Some embodiments integrate a pressure sensor array with an IPRD air vessel. For example a vessel could be screen printed. The pressure sensors can be used to map areas of higher pressure on the body on the body and the pressure vessel can be adjusted (manually and / or automatically) to help reduce / avoid pressure sores. A feedback system may be used to drive pneumatics. For example the device may be able to reposition automatically based on a live pressure mapping data feed. Pressure vessels may be changed rhythmically and / or in sequence. The system may track pressure distribution and / or when a patient is repositioned. Machine learning may be used to predict / anticipate future repositioning requirements. Software-based versions may be provided. Alternatively or additionally analogue logic may be used. Examples: - A Kapton (polyimide) substrate with conductive silver ink. - A screen-printing transfer process to deposit conductive ink onto a polydimethylsiloxane (PDMS) substrate. - Printing conductive ink (silver or carbon-infused) onto a flexible polymer substrate (PET or polyimide). In aspects and embodiments of the present invention one or more of the following features may be provided: - handles - curved corners - fabric welding (no adhesive) - double sealed edges - individual control of chambers - emergency deflation - connectable to a standard 4 bar pressure line - bed hooks - uses a standard 3-pin power supply (medically rated) - air lines run internally - air lines connect at the same place - deflation is slower than inflation - deflation using vacuum - bariatric version - paediatric version - pressure relief valves Different aspects and embodiments of the invention may be used separately or together. The present invention is also described, by way of example, with reference to the accompanying drawings. All orientational terms, such as upper, lower, radially and axially, are used in relation to the drawings and should not be interpreted as limiting on the invention or its connection to a closure. Example embodiments are described in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein. Accordingly, while embodiments can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed and as well as individual embodiments the invention is intended to cover combinations of those embodiments as well. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included. Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate. The terminology used herein to describe embodiments is not intended to limit the scope. The articles “a,” “an,” and “the” are singular in that they have a single referent; however, the use of the singular form in the present document should not preclude the presence of more than one referent. In other words, elements referred to in the singular can number one or more, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and / or “including,” when used herein, specify the presence of stated features, items, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, items, steps, operations, elements, components, and / or groups thereof. Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealized or overly formal sense unless expressly so defined herein. Proning was used extensively throughout the Covid-19 pandemic to significantly improve mortality rates. Due to the risk of pressure sores and nerve injury, prone patients have their heads turned approximately once every two hours. This process currently takes five or more staff members and can take 30-60 minutes to complete. In addition this introduces significant manual handling risks for staff and can dislodge vital lines. The present invention was developed as a device to support turning patients’ heads when they are laying prone in ICU. As illustrated in Figures 1 to 6, medical literature was reviewed and anthropometric data combined with neck flexibility studies to consider the optimum geometry. Figure 1 shows the key at-risk areas for pressure injury. The diagram has been adapted to show the regions along the torso which are safest for the application of pressure due to being less sensitive areas. The abdomen is not marked as an at-risk area for pressure sores; however, it has been excluded from the ‘safe’ zones following further guidance from clinicians. It was advised that adverse pressure on the abdomen can lead to deterioration of the patient’s condition when sedated. This is corroborated by studies showing the critical nature of abdominal pressure in sedated patients. Figure 2: example neck flexibility assessment used in the design of some embodiments. A neck flexibility assessment was carried out to determine the relationship between the flexibility of a patient’s neck and the height at which a patient would have to be lifted to provide clearance for the turning of the head. The design needs to allow for patients, even those with greatly reduced neck flexibility, to have their head turned without displacing the Endotracheal Tube (ETT or Breathing Tube). Due to the large number of variables such as: positioning / number of pillows, neck straightness, head shape and width, a statistically significant relationship was not determined. The alternative method chosen to generate a lifting height was based on using the absolute maximum predicted height requirement, then adding an agreed upon (with a clinician) safety margin including an estimated ETT length of 50mm, taking the total height to 230mm. Figures 3 and 4: example vessel sizing based on anthropometric data. Anthropometric data was used to determine the width and length requirements of the vessel. The key measurements used are illustrated and shown below: | Dats Point 1st Percentile 99th Percentile 1st Percentile 99th Percentile Waist to Shoulder 326.5mm 448.8mm 301.5mm 408.5mm 1 Forearm to Forearm 451.2mm 652.7mm 394.2mm 559.5mm The device 10 of Figure 6 is formed as a cushion that goes under the patient and inflates and deflates, allowing the head to turn without sliding the patient up and down the bed. This helps reduce the number of staff needed to turn the patient and makes it safer for them. It also lowers the risk of patient injuries or mishaps like disturbing a breathing tube. In this embodiment the device 10 has three sub-cushions 15, 20, 25. The sub-cushions 15, 20, 25 are of increasing maximum volume / size / height. Figure 7: a) Inflation (1-3) deflation (4-6), b) control unit with user-friendly interface, c) Rendered overview of entire device 110, d) hospital trial with healthy volunteer. Figure 8 shows a device 210 comprising inflatable, flexible vessel formed as a “rubbery” bag 212 with three inflatable / deflatable chambers 215, 220, 225 under the control of a control box 230 to lift a patient from their torso, allowing their head to be turned manually. A step-by-step diagram of device 310 operation is shown in Figures 9a to 9k. Figure 9a: whilst positioning the sheet under the patient 305 for prone position, the “air mattress” 310 is also slid under the patient. Figure 9b: the mattress can then stay under the patient in the prone position. Figure 9c: plug the pump into the power supply. Figure 9d: plug the pump air-tube into the “air mattress”. Figure 9e: preparing the manoeuvre the patient, one staff member holds the head of the patent and the second operates the pump. Figure 9f: lift the mattress by using the pump. Figure 9g: as the patient’s torso lifts up, the staff member at the head keeps the patient’s level. Figure 9h: once at the top, this staff member then turns the head of the patient to the other side. Figure 9i: then lower the mattress by using the pump controls. Figure 9j: again the patient’s head must be kept level. Figure 9k: disconnect the pump from the mattress and mains, and clean / pack away to take to the next required location. Figure 10 shows a device 410 formed according to a further embodiment. Upper and lower vessel positions can be positioned correctly on the safe lifting locations of the upper chest and across the hip region. To improve versatility for the lower vessel it could, for example, be formed as two or more smaller vessels with separate control. This would allow the medical staff to make their own decision on which vessels are the safest to inflate, based on each patient’s individual need. Features shown include: Figure 10A: Vessel and Pump Assembly Upper lifting vessel 450. Positioned on upper chest region. Rectangular shape chosen based on previous testing. Lower lifting vessel 452. Positioned on hip region. Two large vessels chosen to reduce wrinkles. Valve sub-assembly 454. One-way electric pump 456. Provides required flow rate to inflate vessels. Stitched sheet 458. Holds vessels together underneath he patient, and provides some skin protection. Figure 10B: Valve Sub-Assembly Removable vessel fitting 460. Allows for removal of valve sub-assembly from vessels. 3-way fitting 462. Diverts air from single pump out to two separate vessels. 8mm hose 464. Stiff pneumatic hose removes risk of folding when bent - 8mm diameter matches output of pump. 2 / 2 manual valves 466. Allow individual control of vessel inflation if vessels need to be inflated to different pressures. Exhaust valve 468. 2 / 2 valve can be opened to deflate the vessels. Figure 11 shows a device 510 formed according to a further embodiment. Features shown include: Acrylic casing 470. Pneumatics and electronics encased in an acrylic case with removable lid to reduce noise. Electronics and pneumatics system 472. With pressure sensor included for over-inflation fail safe, and to stop the device when fully inflate. Control panel 474. 4 button user interface with “push and hold” functionality to inflate / deflate vessels. Folded upper edge 476. The vessel is manufactured with a folded upper edge instead of a seam to eliminate folding around the neck region under deflation. 90° elbow push fittings 478. Fittings moved wider than previous versions. 90 fitting helps to keep the tubing along the edge of the vessels, reducing the risk of accidental dislodging. Removable fittings 480. Push-fittings allow for removal of the pneumatics and tubing to leave the deflated device under the patient when not in use. Once piece material 482. The vessel is manufactured from one piece of material, reducing redundant seam space between individual chambers. 2 side fittings 484. Fittings attached to both sides of the vessel to allow for inflation from left / right or both sides. Testing of the device 510 is illustrated in Figures 12a (device deflated under patient at rest) and 12b (device inflated for repositioning of the head) and has shown: 1. The device: - Can be used safely on patients from 1.42 m to 2 m in height (1st-99th percentiles) and weights from 50kg to 100kg. - Successfully elevated the body to allow the head to be turned with ease, then lowered the patient back onto the bed. - Was comfortable to lie on when deflated with no evidence for pressure related injuries. - Substantially reduced the time taken for head turning. 2. 100% of staff said they felt comfortable using the device to perform a head turn with two staff present. 3. There were no complications during testing. Figure 13 shows an IPRD 610 under patient 605 on bed 600, demonstrating multiple inflatable vessels to lift and position patient in a targeted fashion. Slow, controlled movements eliminate safety concerns. A sequence of drawings showing how a patient’s head would be lifted, turned and lowered. The proposed solution comprises a flexible, inflatable air vessel positioned underneath the patient’s torso, which remains deflated under the patient when not in use. A removable pump and control system is used to lift the patient’s upper body, providing the clearance to allow for a clinician to manually turn the patients head. The pneumatic control system comprises a 4-way valve system to both inflate and deflate the vessel in a controlled manner and solenoids allowing individual control of the vessels, this is important when considering a variety of body shapes / sizes. The energy storage and transfer method is via pneumatics, which could be provided either through the use of a pump or using the available 4 Bar pressure medical air system available throughout ICUs. Figures 14 to 16 show pneumatics diagrams for different embodiments of the present invention. Pump and 4-bar examples are shown in Figures 15 and 16. Both systems use 2 Port / 2 Way (2 / 2) Solenoid Valves to allow for selection between the lower vessels, and 3 / 2 valves to divert the air flow to where it is required. In the case of the pump system, the 3 / 2 valves divert the pump intake and output, meaning that the same pump can be used to both inflate and deflate the vessels. A 4 / 2 Solenoid valve was considered for this purpose as this would require just one valve rather than two, however these use ‘pilot’ air pressure to operate, which is not possible when using just a pump. The 4 Bar pressure system uses 2 / 2 valves to divert air flow into a vacuum generator which uses the Venturi effect to create a vacuum - this vacuum is then used to suck the air out from the vessels. Due to the ICU outlet 4 Bar pressure being much higher than the required pressure, a pressure regulator may be required in this design to avoid over inflation and control inflation speed. Figure 17 shows an example electronic schematic. Figure 18 shows an example interaction architecture. Figures 19 and 20 show a device 710 formed according to a further embodiment. The device 710 comprises three (less / more are possible in other embodiments) successively larger air chambers 715, 720, 725 which are served by separate air lines 716, 721,726 and are individually inflatable / deflatable. Over the chambers a pressure sensor mat 730 is provided (only part of which is depicted to show the underlying chambers). The mat comprises a thin, flexible piezoresistive-based pressure sensor array. A control box 750 is provided and in this embodiment has bed hooks 755. An example piezoresistive sensor matrix is shown in Figure 21. This was constructed from copper tape electrodes on a paper substrate to form a 7x7 grid with a piece of Velostat (piezoresistive material) in between. The copper tape is 6mm wide, with 6mm spacing in between rows to give a sensing cell size of 12mm (resolution of 0.83 d / cm). The top layer of copper tape are the columns, and the bottom layer are the rows. The sheet of Velostat is sandwiched in between to act as a pressure varying resistance between each of the 49 intersection points of the matrix. Each row and column is connected to an input on an Arduino microcontroller. Applying pressure to the sensor decreases the resistance of the Velostat which results in an increase in measured voltage of certain rows and columns, which can then be used to create a live-plot of pressure distribution. Since the cross-section of the IPRD vessel in some embodiments is generally constant along its width (all seams are straight and parallel) there would be no out-of-plane deformation or wrinkling expected where the pressure sensor is placed. This is beneficial since wrinkling or stretching the pressure sensor may cause erroneous readings. It also means the pressure sensor only has to be flexible and not stretchy, making material selection of the sensor less restricted. To replace the paper and copper tape used in the initial prototype, one option is to use a screen-printed flexible circuit. Figure 22 shows how this could be constructed using a Kapton (polyimide) substrate 890 with conductive silver ink 895, to give a thickness of 125pm. To replace the Velostat (which can be unreliable and has widely varying material characteristics between samples), polydimethylsiloxane (PDMS) can be synthesised with varying concentrations of CNTs to achieve the same piezoresistive properties seen in Velostat, except with a greater level of control and reliability. A screen-printing transfer process may, for example, be used to deposit conductive ink onto a PDMS substrate. This is beneficial over plastic film required for basic screen printing as PDMS is not as susceptible to creasing or wrinkling and is softer and more flexible than plastic films. The table below shows example product specifications / considerations for aspects and embodiments of the present invention. 1.1 Minimum pressure sensor array spatial resolution < 80 mm spacing 1.2 Ideal pressure sensor array spatial resolution < 20 mm spacing 1.3 Pressure sensor covers entire IPRD 850 x500 mm 1.4 Pressure sensor covers entire hospital bed 900 x2000 mm 1.5 Pressure sensor array sample rate > 0.3 Hz 1.6 Pressure sensor array accuracy ±5 mmHg (±0.6 kPa) 1.7 Minimum pressure sensor array cell saturation pressure > 100 mmHg {13 kPa) 1.8 Data output has minimal noise or artefacts that affect true pressure map visibility Clean data 1.9 1.10 1.11 Pressure sensor array does not introduce hard objects to the IPRD surface Pressure sensor array is flexible Device can automatically reposition based on live pressure mapping data feedback No hard / rigid objects in sensor surface Minimum bend radius <50 mm Closed-loop control of pneumatics for constant repositioning 2. 2.1 Live pressure distribution map can be displayed Real-time display 2.2 Data interface is easily accessible by healthcare workers Attached screen, phone app, or similar 2.3 Device has intuitive user interface - 2.4 Device provides feedback to indicate pressure ulcer formation risk Audio-visual alerts to healthcare staff 2.5 Device can be switched between manual and automatic repositioning easily User i nterface allows mode switch 3.1 3.2 3.3 Sensor array should not cost more to ......manufacture than the IBRD................................. ......... Product does not use non-recyclable plastics Outer surface is non-porous and waterproof No single-use plastics Outer surface is 4. Life in service 4.1 Lifetime number of uses >10 uses 4.2 Device can be reused safely Sterilizable 4,3 Device is sealed and protected from water ingress IP32 4.4 Device is modular and sub-systems can be replaced All sub-systems replaceable 4.5 Device is maintenance friendly Easy access to electronics 4.6 Device has handles for lifting Handles can support 200 kg 4,7 Pressure sensor is thin and unobtrusive < 3 mm total thickness 4.8 Device can be stored easily by one person Rolled or folder without damage repeatedly Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the 5 precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention. References 1 Hospital admitted patient care activity (NHS Digital Leeds, UK, 2020) 2 Guerin, C. et al. N. Engl. J. Med. 368, 2159-2168 (2013) 3 ICS. Intensive Care Staff. Stand. NHS Workforce Crisis (2023) 5 4 King-Robson, J. et al. BMJ Case Rep. CP 15, e243798 (2022) 5 Kerlin, M. P. et al. Crit. Care 24, 98 (2020) 6 Taccone, P. et al. JAMA 302, 1977-1984 (2009) 7 Griffiths, M. J. D. et al. BMJ Open Respir. Res. 6, e000420 (2019) 8 Fernandez, R. et al. Intensive Care Med. 34, 1487-1491 (2008) 10 9 Binda, F. et al. Intensive Crit. Care Nurs. Q7, 103088 (2021) 10 Ayala, K. et al. J. Am. Assoc. Nurse Pract. (2021)

Claims

1. An inflatable prone repositioning device provided as a bag or pillow, the device has only three vessels, the three vessels can be individually inflated and deflated, the bag or pillow is positionable underneath a proned patient, the bag or pillow is configured for use with the three vessels extending generally orthogonal to the length of a patient, whereby, in use, vessels can be selectively inflated to raise a patient’s chest and hips to provide clearance for turning of the patient’s head .

2. A device as claimed in claim 1, in which the bag or pillow is internally divided into multiple vessels.

3. A device as claimed in claim 1, in which separate vessels are provided and an overbag is provided to house the vessels together.

4. A device as claimed in any preceding claim, in which the shape and / or size of each vessel is different from the other two vessels.

5. A device as claimed in any preceding claim, in which at least one of the vessels has a maximally inflated height different to other vessels, whereby the device can assume a wedgelike configuration.

7. A device as claimed in any preceding claim, comprising a quick release mechanism for rapid deflation.

8. A device as claimed in any preceding claim, comprising anti-slip means to prevent slippage.

9. A device as claimed in claim 8, in which the anti-slip means comprises rubber strips.

10. A device as claimed in any preceding claim, further comprising a pressure relief layer.

11. A device as claimed in claim 10, in which the pressure relief layer comprises asecondary layer on the top of the vessels to reduce pressure sores over long term inflation of the device underneath patients.

12. A device as claimed in any preceding claim, comprising means for measuring pressure.

13. A device as claimed in claim 12, in which the means for measuring pressure comprisesa layer.

14. A device as claimed in claim 13, in which the layer is separate from the vessels.

15. A device as claimed in any preceding claim, comprising pressure sensors.

16. A device as claimed in any of claims 12 to 15, comprising a feedback system for identifying areas identified as applying too much pressure and for taking remedial action.

17. A system for proned patient repositioning, the system comprising a device as claimed in any preceding claim to lift a patient from their torso, allowing their head to be turned manually, and a controller for selectively inflating or deflating the vessels individually.

18. A system as claimed in claim 17, in which the controller can provide a predetermined automated inflation and / or deflation sequence of the vessels.

19. A system as claimed in claim 17 or claim 18, in which the controller can provide an automated repetitive inflation I deflation cycle.

20. A method of repositioning a proned patient comprising the steps of:- providing a device as claimed in any of claims 1 to 16 or a system according to any ofclaims 17 to 19;- using the vessels to lift a patient’s torso, freeing their head from a bed;- manually turning the patient’s head;- deflating the vessels; and- lowering the head.

Images