How reliable is measurement of posture during sleep: real-world measurement of body posture and movement during sleep using accelerometers

Objective Understanding sleeping behaviours could improve prevention and treatment of sleep problems and associated health conditions. This study aimed to evaluate a method to assess body posture and movement during sleep using trunk-worn accelerometers for 28 days. Approach Participants (50 adults with low back pain (66% female); aged 32(±9) years) wore two activPAL-micro sensors (thigh, trunk) during their normal daily life for 28 consecutive days. Parameters related to body posture (e.g., time spent lying supine or prone) and movement (e.g., number of turns) during sleep were calculated for each night. Average values for each parameter were identified for different periods, the Spearman-Brown Prophecy Formula was used to estimate the minimum number of nights required to obtain a reliable estimate of each parameter, and repeatability of measures between different weeks was calculated. Main Results Participants spent 8.1(±0.8) hours asleep and most time (44%) was spent in a supine posture. The minimum number of nights required for reliable estimates varied between sleep parameters, range 4-21 nights. The most stable parameters (i.e., requiring less than seven nights) were “average activity”, “no. of turns”, “time spent prone”, and “posture changes in the first hour”. Some measures differed substantially between weeks. Significance Most sleep parameters related to body posture and movement require a week or more of monitoring to provide reliable estimates of behaviour over one month. Notably, one week may not reflect behaviour in another week, and the time varying nature of sleep needs to be considered.

INVESTIGATION OF THE RELATIONSHIP BETWEEN ANTHROPOMETRIC MEASUREMENTS AND FOREARM POSTURES WITH GRIP STRENGTH IN YOUNG ADULTS

BACKGROUND: Grip strength is widely accepted as an indicator of maximum hand strength and contraction of active muscles of the hand and forearm. OBJECTIVE: The aim of this study was to assess the effects of forearm posture (pronation, supination and neutral) and anthropometric variation on MVC grip strength and grip endurance time in young university adults. METHODS: Fifty healthy, right-handed men volunteered to participate in this study. The experiment was characterized by measuring MVC grip strength and endurance time of 50% MVC randomly in three different postures (supine, pronation and neutral). Performance was assessed in terms of dependent variables: MVC grip strength and grip endurance time. RESULTS: MANCOVA results showed no significant effect of posture on MVC grip strength ([Formula: see text]) and grip endurance time ([Formula: see text]). There was a significant effect of age ([Formula: see text]), height ([Formula: see text]) and forearm length ([Formula: see text]) on the grip endurance time in supine position. However, palm circumference had a significant effect on MVC grip strength ([Formula: see text]) in pronation posture only. The pronation forearm posture produces 7.4% more grip strength than a supine posture. In addition, the grip endurance time was improved in the supine position, compared to the neutral and pronation forearm posture. CONCLUSIONS: This study showed that the MVC grip strength is affected by the weight and palm circumference. In addition, palm circumference was the most influential factor affecting grip strength. Thus, anthropometric and posture-specific grip strength data are essential for clinical and industrial applications. The results can be used to prepare guidelines for rehabilitation, health care, sport and medicine.

O015 Upper airway collapsibility measurement under anaesthesia in children: feasibility and utility in predicting perioperative respiratory adverse events

Background Perioperative respiratory adverse events (PRAE) pose significant risk in paediatric anaesthesia, and identifying risk is vital. Perioperative measurement of pharyngeal closing pressure (PCLOSE) is a quick, objective method of assessing upper airway collapsibility that may identify PRAE risk. Aim To investigate if PCLOSE measurement is feasible and predictive of PRAE in children. Method Fifty-six children (1-8years, 34 male, without significant co-morbidities) underwent PCLOSE measurements immediately preceding (pre-PCLOSE) and following (post-PCLOSE) adenotonsillectomy. Measurement was performed under anaesthesia while breathing spontaneously in supine posture with head/jaw neutral. After application of a face mask, inspiratory flow was occluded with an associated decrease in mask/nasal pressure seen with each inspiratory effort. With airway collapse, a plateau developed in minimum pressure observed (= PCLOSE): less collapsible airways occluded at more negative pressures. PCLOSE was averaged over 5–6 sequential efforts, at least 3 times on each occasion. Results Both pre-and post-PCLOSE were successfully measured in 94.6% children without affecting procedure. Pre-PCLOSE and change in PCLOSE from pre- to post- were associated with an increased incidence of PRAE (Poisson regression coefficient 0.083(0.03) (mean, SE); p=0.0054 and 0.03(0.01); p=0.018, respectively). There was no significant association between post-PCLOSE and PRAE. The odd of PRAE occurrence during recovery was 1.5 times higher than in other phases. Conclusion This study demonstrated the feasibility of obtaining PCLOSE. A more collapsible airway before surgery and an increase in collapsibility with surgery were both associated with increased PRAE. PCLOSE measurement could be a valuable risk assessment tool for PRAE in children undergoing surgery.

Development and Clinical Evaluation of Bed with Standing-Up Function

The risk of disuse syndrome caused by prolonged supine posture in hemiplegic stroke in- and outpatients has become a social problem. This study aimed to develop a new bed with a standing-up function, allowing medical caregivers and patients to freely take a standing position on the bed to reduce the amount of time spent in the supine position and to clarify its effectiveness through evaluation of its usability and clinical use. In addition to the Gatch function of the developed bed, it allows transition from a supine position to a chair-sitting or standing position on the bed, and from a standing position to walking action. In addition, as with the tilt table used for standing-position training, the bed’s tilt angle can be adjusted, reducing the load on the lower limbs and allowing appropriate rehabilitation to be carried out anytime, consequently reducing the burden of nursing care. The bed was developed with the cooperation of a specialized bed manufacturer and supported by public funds, and clinical evaluation was conducted after confirming its safety. We evaluated the physical and physiological functions of two hemiplegic patients after 4 weeks of standing training using a prototype bed, to which results from the six-item test showed no significant improvement. However, medical professionals, such as doctors, nurses, and physical therapists, who participated in the clinical evaluation indicated that the bed can safely replace the tilt table for standing-position rehabilitation, and it is effective in eliminating related human and time burdens.

Mechanical Countermeasures to Headward Fluid Shifts

Head-to-foot gravitationally-induced hydrostatic pressure gradients in the upright posture on Earth are absent in weightlessness. This results in a relative headward fluid shift in the vascular and cerebrospinal fluid compartments and may underlie multiple physiological consequences of spaceflight, including the Spaceflight Associated Neuro-ocular Syndrome. Here, we tested 3 mechanical countermeasures (lower body negative pressure [LBNP], veno-constrictive thigh cuffs [VTC] and impedance threshold device [ITD] resistive inspiratory breathing) individually and in combination to reduce a posture-induced headward fluid shift as a ground-based spaceflight analog. Ten healthy subjects (5 male) underwent baseline measures (seated and supine postures) followed by countermeasure exposure in the supine posture. Noninvasive measurements included ultrasound (internal jugular veins [IJV] cross-sectional area, cardiac stroke volume, optic nerve sheath diameter, noninvasive IJV pressure), transient evoked otoacoustic emissions (OAE; intracranial pressure index), intraocular pressure, choroidal thickness from optical coherence tomography imaging, and brachial blood pressure. Compared to the supine posture, IJV area decreased 48% with application of LBNP (mean ratio: 0.52, 95% CI: 0.44-0.60, P<0.001), 31% with VTC (mean ratio: 0.69, 95% CI: 0.55-0.87, P<0.001), and 56% with ITD (mean ratio: 0.44, 95% CI: 0.12-1.70, P=0.46), measured at end-inspiration. LBNP was the only individual countermeasure to decrease the OAE phase angle (Δ -12.9 degrees, 95% CI: -25 to -0.9, P=0.027), and use of combined countermeasures did not result in greater effects. Thus, LBNP, and to a lesser extent VTC and ITD, represent promising headward fluid shift countermeasures, but will require future testing in analog and spaceflight environments.

Supine-Related Pseudoanemia in Hospitalized Patients

A patient’s supine posture redistributes plasma into the vascular space, leading to dilution of blood constituents. The extent to which posture may influence identification of hospital-acquired anemia is unknown. Patients in this quasi-experimental study had blood obtained for hemoglobin measurement while recumbent for at least 6 hours, and then again after sitting upright for at least 1 hour. Of the 35 patients who completed the study, 13 were women (37%). Patients had a median increase in hemoglobin of 0.60 g/dL (range, –0.6 to 1.4 g/dL) with sitting, a 5.2% (range, (–4.5% to 15.1%) relative change (P < .001). Ten of 35 patients (29%) exhibited an increase in hemoglobin of 1.0 g/dL or more. Posture influences hemoglobin levels in hospitalized patients on general medicine wards; this knowledge may help curb unnecessary testing to evaluate small changes in hemoglobin concentration.

Impact of Prone Position on 12-Lead Electrocardiogram in Healthy Adults: A Comparison Study with Standard Electrocardiogram

Background. The standard electrocardiogram (ECG) is commonly performed in the supine posture. It may be difficult to report ECG in a supine posture for those who are unable to adopt the supine posture because of certain circumstances such as acute respiratory distress syndrome—patients who are placed in a prone position for long periods to improve oxygenation. Few data are available on the impact of the prone position on the ECG recording with electrodes on the posterior chest. Examining and analyzing the type and extent of changes observed in the prone ECG in healthy adults have become vitally valuable. Methods. A cross-sectional observational study enrolled forty healthy adults (24 males and 16 females) aged between 18 and 40 years. The ECG was performed in two different body positions, supine and prone. Influence of prone position on the heart rate, mean QRS axis, amplitude, morphology, duration, mean T wave axis and polarity, mean P wave axis, PR, and mean QTc duration was evaluated. Results. The mean heart rate was higher in the prone position (73.2 ± 12.4 bpm) compared with the supine position (69.5 ± 11.5 bpm, p = 0.03). The QRS duration decreased considerably from supine (92.8 ± 12.6 ms) to prone (84.9 ± 11.9 ms, p < 0.001 ). The mean QRS axis moved to the left in the prone posture (40.5° ± 32°) relative to the supine (49° ± 28°, p = 0.015 ). The QRS amplitude in the precordial leads was significantly decreased from supine (7.42 ± 3.1 mV) to prone (3.68 ± 1.7 mV, p < 0.001 ). In addition, changes in the QRS morphology in leads V1–V3 with the appearance of new Q waves were noted. A notable variation in the mean corrected QT (QTc) period with decrease in duration in prone posture ECG (385 ± 64.8) relative to supine (406 ± 18.8, p = 0.05 ). Conclusions. Prone position ECG resulted in significant changes in healthy adults that should be aware of this as this can affect diagnosis and management strategies. Further studies are needed to investigate the impact of prone position on ECG recording in patients with cardiovascular diseases.

A Smart IoT System for Detecting the Position of a Lying Person Using a Novel Textile Pressure Sensor

Bedsores are one of the severe problems which could affect a long-term lying subject in the hospitals or the hospice. To prevent lying bedsores, we present a smart Internet of Things (IoT) system for detecting the position of a lying person using novel textile pressure sensors. To build such a system, it is necessary to use different technologies and techniques. We used sixty-four of our novel textile pressure sensors based on electrically conductive yarn and the Velostat to collect the information about the pressure distribution of the lying person. Using Message Queuing Telemetry Transport (MQTT) protocol and Arduino-based hardware, we send measured data to the server. On the server side, there is a Node-RED application responsible for data collection, evaluation, and provisioning. We are using a neural network to classify the subject lying posture on the separate device because of the computation complexity. We created the challenging dataset from the observation of twenty-one people in four lying positions. We achieved a best classification precision of 92% for fourth class (right side posture type). On the other hand, the best recall (91%) for first class (supine posture type) was obtained. The best F1 score (84%) was achieved for first class (supine posture type). After the classification, we send the information to the staff desktop application. The application reminds employees when it is necessary to change the lying position of individual subjects and thus prevent bedsores.