Effect of oxygen on tachycardia and arterial oxygen saturation during colonoscopy.

OBJECTIVE: To evaluate the effect of supplementary oxygen on heart rate and arterial oxygen saturation during colonoscopy. DESIGN: Controlled study. SETTING: Two university hospitals, Denmark. SUBJECTS: 40 patients having colonoscopy. INTERVENTIONS: 20 patients were given supplementary oxygen through nasal prongs (2 L/min), and 20 patients breathed room air during colonoscopy. All patients were given conscious sedation and were monitored with a pulse oximeter during colonoscopy. MAIN OUTCOME MEASURES: Tachycardia (pulse rate>100 min(-1)) and arterial oxygen desaturation (SpO2<90%) during colonoscopy. RESULTS: There were no differences in the incidence of tachycardia or mean heart rate during endoscopy between the two groups, and no patient developed symptomatic cardiac arrhythmias or hypotensive episodes. 10 patients in the room air compared with none in the oxygen treatment group (p = 0.0004) had one or more episodes during which arterial oxygen saturation fell below 90% during colonoscopy, and mean oxygen saturation was higher in the oxygen treatment group than in the room air group (p < 0.001). No clinical complications occurred in either group. CONCLUSION: Hypoxaemia and tachycardia are common during routine colonoscopy. The use of supplemental oxygen prevented hypoxaemia, but had no significant effect on heart rate.