Comparison of Distal Limb Warming With Fluidotherapy and Warm Water Immersion for Mild Hypothermia Rewarming

Objective.-The purpose of the study was to determine the effectiveness of Fluidotherapy rewarming through the distal extremities for mildly hypothermic, vigorously shivering subjects. Fluidotherapy is a dry heat modality in which cellulose particles are suspended by warm air circulation. Methods.-Seven subjects (2 female) were cooled on 3 occasions in 8 degrees C water for 60 minutes, or to a core temperature of 35 degrees C. They were then dried and rewarmed in a seated position by 1) shivering only; 2) Fluidotherapy applied to the distal extremities (46 +/- 1 degrees C, mean +/- SD); or 3) water immersion of the distal extremities (44 +/- 1 degrees C). The order of rewarming followed a balanced design. Esophageal temperature, skin temperature, heart rate, oxygen consumption, and heat flux were measured. Results.-The warm water produced the highest rewarming rate, 6.1 degrees C.h(-1), 95% CI: 5.3-6.9, compared with Fluidotherapy, 2.2 degrees C.h(-1), 95% CI: 1.4-3.0, and shivering only, 2.0 degrees C.h(-1), 95% CI: 1.2-2.8. The Fluidotherapy and warm water conditions increased skin temperature and inhibited shivering heat production, thus reducing metabolic heat production (166 +/- 42 W and 181 +/- 45 W, respectively), compared with shivering only (322 +/- 142 W). Warm water provided a significantly higher net heat gain (398.0 +/- 52 W) than shivering only (288.4 +/- 115 W). Conclusions.-Fluidotherapy was not as effective as warm water for rewarming mildly hypothermic subjects. Although Fluidotherapy is more portable and technically simpler, it provides a lower rate of rewarming that is similar to shivering only. It does help decrease shivering heat production, lowering energy expenditure and cardiac work, and could be considered in a hospital setting, if convenient.