Abstract

Oxygen saturation in eighty-two patients having elective urologic and gynecologic procedures in the lithotomy position using spinal anesthesia was studied to determine if clinically significant changes of oxygen saturation occurred during these procedures. The oxygen saturation was measured using the pulse oximeter and recorded on a paper chart recorder. Forty-eight patients sustained a normal oxygen saturation throughout the procedure. Twenty-one patients showed a trend of falling oxygen saturation of 3.4% (range: 2-6%). Fourteen patients had transient changes of less than 2-minute durations with falls in oxygen saturation averaging 6.4% (range: 2-14%). Minor artifacts in the oxygen saturation trace occurred in 28 patients, and major artifacts preventing interpretation of the oxygen saturation occurred in 10 patients. There was no correlation between the changes in oxygen saturation observed and the age, weight, height, body mass index, physical status, or height of the spinal block. The effects of hypotension and sedation on oxygen saturation during spinal anesthesia needs further study. It was therefore concluded that although a minimum of patients have clinically significant oxygen desaturation while breathing air during these surgical procedures, oxygen administration would minimize the risk of significant hypoxia.