Venous Pooling in Suspension Syndrome Assessed with Ultrasound

Abstract

Introduction: Suspension syndrome describes a potentially life-threatening event during passive suspension on a rope. The pathophysiological mechanism is not fully understood; however, the most widespread hypothesis assumes blood pools in the lower extremities, prompting a reduction in cardiac preload and cardiac output and leading to tissue hypoperfusion, loss of consciousness, and death. The aim of this study was to assess venous pooling by ultrasound in simulated suspension syndrome using human subjects. Methods: In this trial, 20 healthy volunteers were suspended in a sit harness for a maximum of 60 min with and without preceding exercise. Venous pooling was assessed by measuring the diameter of the superficial femoral vein (SFV) with ultrasound at baseline in supine and standing positions as well as during and after suspension. Results: SFV diameter increased and blood flow became progressively sluggish. In 30% of the tests, near syncope occurred. However, SFV diameter did not differ between subjects with and without near syncope. Conclusions: Free hanging in a harness leads to rapid venous pooling in the lower limbs. The most important measure to prevent suspension syndrome might be constant movement of the legs.