Periodic Weight Measurement for Bedridden Patients Using a Pressurized Liquid-Filled Channel System Integrated with Hospital Beds

Variations in body fluids in a short time can lead to significant health issues. The risk due to body fluid variations increases for critically ill and bedridden patients. Changes in body weight in short intervals are the primary indicator of body fluid imbalances. The clinical practice for periodic monitoring of body weights of critically ill or bedridden patients includes a dedicated weighing scale or lift scale, detachable or built-in units of weighing scale on to the legs of hospital cots or as integrated bed scales attached permanently to the cot. However, these methods have limited mobility and usability in a practical setting and often require the involvement of multiple personnel to measure the body weight of a bedridden patient. Owing to such constraints, periodic monitoring of body weights is seldom recorded. In this work, we propose a novel measurement scheme for periodic monitoring of body weight. The prototype consists of an active (piston-based syringe pump) pressurized liquid-filled flexible and elastic channel sandwiched between the hospital cot and mattress. The required displacement of the syringe pump to achieve an optimal internal pressure is calibrated with the known weights. A calibration model (R² = 0.99, p < 0.001) is developed that maps the displacement of the piston pump in mm to known weights in kg for the range 0 to 90 kg. Using the calibration model, the accuracy and precision of the system are characterized at various loading conditions. A practical scenario of rising body weights was emulated as an invitro-experiment, resulting in a maximum error of 3%. The design of the system is modular, so it can easily be integrated with any type of hospital bed. This design is proof of concept for using alternative technologies for weight measurement over periodic intervals, where conventional designs seem cumbersome.