[Effect of intravenous anesthetic premedication using diazepam and fentanyl on the arterial oxygen saturation. A pulse-oximetric study].

The effects of anesthetic premedication with diazepam and phentanyl on the arterial oxyhemoglobin saturation (SpO2) were monitored with a pulsioximeter (BIOX 3700, Ohmeda) in 83 patients scheduled for traumatologic and orthopedic surgery who had baseline SpO2 higher than 95%. Premedication was carried out with phentanyl (0.1 mg) and diazepam (2.5 mg increments) until a somnolence state (eye closure), reversible with verbal stimuli, was achieved. The patients were breathing room air during the study. Premedication induced a significant reduction of SpO2 (p less than 0.001) from baseline values of 96.6 +/- 1.2% to 92.7 +/- 2.9% after sedation and to minimal values of 85.9 +/- 6.1%. In 60 patients (72.3%), minimal SpO2 was lower than 90%, and it was lower than 85% in 32 (38.8%). However, 34 of them (73.3%) recovered a SpO2 higher than 90% with verbal respiratory stimuli, but 16 (26.7%) only did so with oxygen administration. Cyanosis was not detected in any case. Minimal saturation was significantly correlated with baseline SpO2, age and smoking habit. Pulsioximetric monitoring or, if not available, routine oxygen administration, are recommended in patients undergoing pharmacological sedation.