Indirect calorimetry methods for determination of energy expenditure.
Brief history and development of calorimetric methods for the determination of energy expenditure are discussed. The author demonstrates the measuring principles of direct and indirect calorimetry. In two clinical studies the practical use of closed and open technique of indirect calorimetric measurements are presented. In 10 operated patients under isoflurane-nitrous oxide anaesthesia in closed breathing circuit dose related decrease of oxygen consumption and carbon dioxide production was found. The indirect calorimetry showed higher mean energy expenditure (+14%) than was calculated by the Brody-Kleiber formula. These values indicate that the metabolic response due to surgical stress exceeds the metabolism decreasing effect of anaesthesia. The modalities of exact determination of energy expenditure of septic patients under respiratory treatment are discussed. Data of modified Harris-Benedict equation adapted to clinical conditions and of continuous indirect calorimetric measurement of energy expenditure were compared in 25 septic patients. The measured and the calculated mean values showed good correlation (r = 0.82). The modified Harris-Benedict equation may be properly used in clinical practice, when indirect calorimetric measuring instrument is unavailable.
Dárdai
E
E
2nd Department of Surgery, Semmelweis University Medical School, Budapest, Hungary.
D002153:Calorimetry, Indirect / Q000295:instrumentation / Q000379:methods*; D002245:Carbon Dioxide / Q000502:physiology; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D012119:Respiration
D002245:Carbon Dioxide