Oxygen desaturation and changes in breathing pattern in patients undergoing colonoscopy and gastroscopy

The respiratory effect of diagnostic colonoscopy and upper endoscopy were studied in 32 elderly patients. Twenty-two underwent colonoscopy and 10 upper endoscopy. In the group undergoing upper endoscopy, 4 of 10 patients experienced a decrease in oxygen desaturation ≥4% during the medication period; an additional 2 patients desaturated during the procedure. In the group undergoing colonoscopy, 12 of 22 patients experienced oxygen desaturation during the medication period; 3 other patients desaturated during the procedure. Mean SaO₂ for each group was lowest (p<0.05) during the medication period. Central apneas occurred in 13 of the patients undergoing colonoscopy during the medication period; however, only 8 of these patients with apneas experienced desaturation ≥4% and the periods of desaturation did not correlate with the periods of apneas. Oxygen desaturation ≥4% occurs frequently during both upper endoscopy and colonoscopy in this elderly population. This is related to the effects of sedation; the procedure itself worsened the desaturation in only 16% of the patients. Furthermore, the desaturation did not correlate with changes in the breathing patterns of the patients. Low-flow oxygen and/or close monitoring of patients during and subsequent to administration of medication is advised.