Burn wound evaporation--measurement of body fluid loss by probe evaporimeter and weight change.

A knowledge of the rate of fluid loss from the body is a useful aid in planning treatment of patients with severe burns. Different methods for obtaining this data have been investigated. Evaporation rates recorded from a probe evaporimeter have been compared with gravimetric measurements. The evaporimeter underestimated evaporation, especially at high levels, but could be calibrated against known evaporation rates. Estimates of whole-body fluid loss have been made from calibrated evaporimeter data and results compared with measurements of fluid loss by weight change for three patients. Problems with assessing whole-body evaporation rates in the clinical environment are highlighted. Weight change gives a more accurate assessment of total body fluid loss, but considerable effort is necessary to record all relevant information. Probe evaporimeter measurements are simple to perform and allow local evaporation rates to be estimated, but results should be treated with caution. Evaporation rates from wounds of 17 patients with severe burns have been evaluated in terms of surface diffusion resistances. The diffusion resistances of some burn wounds increased with time, but many did not change significantly during the first ten days after injury, and there was considerable variation with burn type and severity.