Heat losses associated with continuous venovenous haemodiafiltration in intensive care patients

Abstract

Objective: To determine the magnitude of heat loss associated with the use of continuous venovenous haemodiafiltration (CVVHD), and the effect of warming the dialysate and insulating the circuit. Design: Extracorporeal temperature decrease was measured by thermocouples inserted into injectate sensor housings across the standard CVVHD circuit, and across circuits with dialysate warmed in a 40°C bath and/or insulated by aluminium foil. Setting: Intensive Care Unit (ICU) of a tertiary referral centre. Subjects: Twelve critically ill patients undergoing CVVHD. Main results: Mean extracorporeal temperature decrease using a standard circuit was 4.4°C (95% confidence interval [CI], 3.9-4.7), 3,000 kJ (710 kcal) per day would be required on average to maintain thermal homeostasis. Warming dialysate fluid reduced mean temperature decrease to 2.9°C (95% CI, 2.7-3.2), but aluminium foil insulation did not have a significant effect. Conclusion: Heat loss is a significant proportion of expected daily energy requiremen...