Metabolic responses--(VO2, VCO2 and energy expenditure)--associated with nasal intubation of the trachea.

The effect of nasotracheal intubation on oxygen consumption (VO2), carbon dioxide production (VCO2), and resting energy expenditure (REE) was studied in 12 critically ill patients. All patients were given midazolam 0.3 mg/kg and etomidate 0.3 mg/kg followed by 8 mg of vecuronium to facilitate intubation. After nasotracheal intubation the patients were mechanically ventilated with an Erica Engström ventilator and connected to an Engström metabolic computer (EMC). Carbon dioxide production was measured using an infrared CO2 analyzer. Resting energy expenditure was calculated by the EMC, which incorporated an oxygen cell for VO2 measurement. VO2, VCO2, and REE were recorded 5, 10, 15, 20, 25, and 30 minutes after intubation. High values of the above parameters were observed 5 minutes after intubation, values that gradually declined during the next 25 minutes. At 25 and 30 minutes after intubation VO2 was 25% and 27% lower (P = 0.054) than the VO2 at 5 minutes after intubation. Carbon dioxide production and REE were also lower 10, 15, 20, 25, and 30 minutes after intubation but were not significantly different from values obtained at 5 minutes. The increase in VO2 associated with nasotracheal intubation may be detrimental for patients already suffering from hypoxia.