Assessment of Convective Heat Loss From Humans in Cold Water

Convective heat loss is a primary cause of hypothermia in humans undergoing water immersion, particularly for swimmers and divers at relatively shallow depths. Various biophysical models have been advanced to account for body heat loss in water of different temperatures and cold stress, most of which have made use of physiological data obtained with easily applied classical thermometry techniques. Explicit techniques for the determination of body heat loss must involve direct calorimetry or the use of heat flow transducers, techniques which are difficult to apply in realistic simulations of actual cold water exposure. This paper describes these latter two techniques in some detail, concentrating on the accuracy to be attained and the calibration necessitated with each method. Results obtained with each method specific to heat loss determination at surface and both dry and wet hyperbaric exposures are shown, illustrating the types of data that can be attained.