Standard and alternative methods of stretcher carriage: performance, humanfactors, and cardiorespiratory responses

Transporting a casualty on a stretcher is a common task for medical and mil itary personnel. Stretchers are usually carried by hand, but distributing t he load to other parts of the body may have advantages. To examine alternat ive carriage methods, ii soldiers walked on a treadmill at 4.8 km/h while p erforming two-person carries of a stretcher containing an 80-kg manikin. In separate trials, soldiers carried the stretcher using: (1) hand carriage, (2) shoulder straps, (3) a specially designed harness that allowed load shi fting between the hips and shoulders (hip-shoulder system), and (4) a clip that fitted on the belt of standard military load carrying equipment (LCE) and placed the stretcher mass mainly on the hips. With each system, subject s walked until volitional fatigue or 30 min. While walking, expired gases a nd heart rates were obtained and subjects rated their perceived exertion (B org Scale). At the conclusion of all four trials, subjects rated each syste m on a number of subjective measures. Results showed that average (+/- SD) carriage times were 2.7 +/- 1.4, 14.5 +/- 8.3, 25.4+/-8.1, and 21.7+/-9.9 m ill with the hand, shoulder, hip-shoulder and LCE systems respectively (p<0 .01). Hand carriage resulted in considerably more cardiorespiratory stress (higher heart rate and minute ventilation, p<0.05) than the other three sys tems, but there were few consistent differences among the other three syste ms. Perceived exertion in the upper body was less with the hip - shoulder a nd LCE systems than with the other two systems (p<0.05). Subjects preferred the hip-shoulder and LCE systems overall and for specific subjective chara cteristics such as comfort, ease of use and stability (p<0.01). These data indicate that moving the stretcher load from the hands and placing that loa d on the shoulders and/or hips results in improved performance, reduced car diorespiratory stress and favourable subjective evaluations. Further develo pmental work should focus on the hip-shoulder and LCE systems.