Laryngeal microsurgery under general anesthesia using small-bore endotracheal tubes: blood gas analysis.

This study reports variations observed under general anesthesia through small-bore endotracheal tubes in PO2, PCO2, HCO3, percentage saturation of O2, and pH levels in 39 patients who underwent laryngeal microsurgery lasting from 10 to 100 minutes. The tendency to an increase in PCO2 levels reached statistical significance only at the 100th minute but did not constitute a risk for patients as values remained within the limits of "permitted hypercapnia." PO2, percentage saturation of oxygen, and HCO3 levels did not vary significantly. pH values tended to fall (respiratory acidosis) in correlation to the increase in PCO2. Small-bore endotracheal tubes can safely be used for laryngeal microsurgery when operating times are not longer than 100 minutes.