Effect of premedication on arterial oxygen saturation in children with congenital heart disease.

The effect of a standardized intramuscular premedication (morphine, 0.1 mg/kg, scopolamine, 13 micrograms/kg, and secobarbital, 2.5 mg/kg) on the arterial oxygen saturation of hemoglobin was evaluated in 33 patients with congenital heart disease by use of the Nellcor pulse oximeter. Sixteen patients had noncyanotic congenital heart disease and 17 patients had cyanotic congenital heart disease. In the noncyanotic congenital heart disease group, pulse oximeter saturations decreased from 98.1% +/- 1.5% (mean +/- SD), before premedication, to 96.5% +/- 1.5% following premedication. Although this decrease was statistically significant (P less than 0.05), it was determined to not be clinically meaningful. In the patients with cyanotic congenital heart disease, oxygen saturation increased from 73.5% +/- 11.8 to 74.7% +/- 10.2 following premedication, but this change was not statistically significant. The effect of premedication on SaO2 was highly variable in patients with cyanotic heart disease; although the group mean appeared to increase, 6 of the 17 patients had decreases in saturation and the decrease exceeded 10% in saturation in 3 of them. Therefore, oxygen saturation should be monitored following premedication in patients with cyanotic heart disease and oxygen administered as needed.