O-293 Motionless Suspension in Full-Body Harnesses: Perceived Discomfort, Strap Pressure and Physiological Response of Human Subjects

Introduction Falls from height are one of the leading causes of occupational injuries in most countries. A way of protecting workers against falls from height is to choose personal fall arrest systems, which implies the wear of a safety harness. Following a fall arrest, motionless suspension in a full-body harness can be hazardous and lead to death due to suspension trauma syndrome, which has long been known. This paper investigates the perception of discomfort, the pressure exerted by the straps on the body and the evolution of physiological parameters in 10-minute motionless suspension. Materials and Methods For this study, 30 male and 30 female were suspended from the dorsal D-ring, in four different commercial harnesses (one X, one Y and two H configuration harnesses). During suspension, participants rated their perceived discomfort on a visual analog scale for different body regions every 2 minutes and physiological parameters were recorded continuously throughout the suspension. Pressures exerted by the straps were measured for a short period using pressure mats. Results and discussion The results show that H-configuration harnesses, which are very common in the construction industry and often the cheapest models, are perceived to be the least tolerable in suspension. Moreover, H-configuration harnesses lead to greater reduction in muscular blood oxygenation and greater increase in the heart rate, which could make this type of harness hazardous for prolonged motionless suspension. The Y-configuration harness seems to be the best performer in suspension. The X-configuration creates a constriction effect around the neck during motionless suspension, which causes a significant increase in heart rate and decrease in cerebral oximetry.