[CO2 production and thermogenesis induced by enteral and parenteral nutrition].
The objectives of this study were to quantify, in critically ill patients, the thermogenesis induced by artificial nutrition (AN), when the caloric supply restores the energetic losses, and to evaluate the effects of the AN suppression on the production of CO2 (VCO2).


METHODS
20 patients were studied, 14 with mechanical ventilation and 6 with spontaneous respiration, divided into two groups, depending on whether the AN was enteral (EN) or parenteral (PN). The VCO2 and the consumption of oxygen (VO2) were measured by means of the Douglas bag. The resting energy expenditure during the AN (REET) and 2 hours after discontinuing the AN (REE) were measured. The thermogenesis induced by the nutrition (TIN) was defined as the difference between REET and REE, expressed as a percentage of the caloric supply.


RESULTS
After discontinuing the AN, there were no statistically significant differences between EN and PN patients in the VCO2 decreases (p = 0.60) and the VO2 decreases (p = 0.78), and in the TIN percentage referred to the caloric supply (p = 0.82). After discontinuing the caloric supply, which was 1.12 times the REET, the VCO2 decreased 5 +/- 4.9% (Confidence interval (CI) of 95%, from 3% to 7%), the VO2 decreased 2 +/- 6.1% (CI of -0.36% to 5.32%), and the TIN represented 3 +/- 4.5% of the caloric supply (CI of 0.72% to 4.95%).


CONCLUSIONS
The results of this study indicate that the thermogenesis induced by artificial nutrition, when restores the energetic losses, is equivalent to 3% of the caloric supply. The discontinuation of the artificial nutrition induced a VCO2 decrease of 5% and thus this measure would probably not be useful for decreasing the ventilatory demand.
Raurich
J M
JM
Servicio de Medicina Intensiva, Hospital Son Dureta, Palma de Mallorca, España.
Ibáñez
J
J
Marsé
P
P
D000293:Adolescent; D000328:Adult; D001833:Body Temperature Regulation; D002245:Carbon Dioxide / Q000502:physiology*; D016009:Chi-Square Distribution; D002149:Energy Intake; D004734:Energy Metabolism; D004750:Enteral Nutrition / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D010288:Parenteral Nutrition / Q000706:statistics & numerical data; D012121:Respiration, Artificial
D002245:Carbon Dioxide
Producción de CO2 y termogénesis inducidas por la nutrición enteral y parenteral.