Short-acting barbiturate sedation: effect on arterial pH and PaCO2 in children.

One hundred and fifteen unpremedicated children, induced with thiamylal, a short-acting thiobarbiturate, administered rectally (25 mg.kg-1 body wt) or intravenously (6 mg.kg-1) had arterial pH of 7.36 +/- 0.03 and PaCO2 of 40 +/- 4 mmHg. In 22 children over two years of age, the use of fentanyl (1.2 +/- 0.7 microgram.kg-1) in addition to the thiamylal did not change blood gas data compared to those children over two years receiving only barbiturates (pH 7.36 vs 7.36, PaCO2 41 vs 40 mmHg). Children with cyanotic congenital heart disease showed similar pH and PaCO2 to acyanotic children following administration of the short-acting barbiturate. Thiobarbiturates, given in a titrated fashion under direct observation, have clinically small effects on arterial pH and PaCO2 in paediatric patients.