Risk factors associated with changes in oxygenation and pulse rate during colonoscopy

Although hypoxemia is a relatively common complication of colonoscoy, the possible predictive factors of oxygen desaturation and tachycardia in patients undergoing this procedure are not well known. In this study, the possible predictive factors of severe oxygen desaturation (SaO2<90%) and tachycardia in patients with undergoing colonoscopy were investigated.

A total of 79 consecutive patients were evaluated in the study (46 men and 33 women). Significant oxygen desaturation was considered to be a reduction of arterial oxygen saturation (SaO2) to less than 90%. Tachycardia was defined as a heart rate above 100/min. Patients with inadequate colonoscopy were excluded from the study. The incidence of arterial hemoglobin oxygen desaturation and changes of heart rate during colonoscopy were evaluated and clinical factors in relation to these findings were assessed.

The SaO2 during colonoscopy fell below 90% in 19 of the 79 patients (24.1%). The risk factors for desaturation were advanced (>60yr) age (OR: 6.03; 95% CI, 1.35-26.99), receiving sedation (OR: 11.42; 95% CI, 2.05-63.49), chronic lung disease (OR: 4.54; 95% CI and 1.40-11.68), and obesity (OR: 8.95; 95% CI, 1.17-68.55). The presence of hypertension and anemia, a history of cigarette smoking and duration of the colonoscopy had no significant effect on arterial oxygen desaturation (p>0.05). The pulse rate was raised above 100/min during colonoscopy in 26 of 79 patients (32.9%). lncrease in heart rate was found to be related to arterial oxygen desaturation (OR: 13.72; 95% CI, 2.67-70.32), anemia (OR:6.17; 95% CI, 1.15-32.91) and advanced (>60 yr) age (OR: 6.08; 95% CI, 1.62-22.81). Gender, sedation, obesity, hypertension, chronic lung disease and smoking did not affect the heart rate (p>0.05). Two patients had transitional bradyarrythmia, which had no relationship with the parameters studied. There was no incidence of significant hypoxia or change in heart rate which might have caused termination of the procedure.

Benign and transient arterial oxygen desaturation and tachycardia may occur during colonoscopy procedure. Sedation, obesity, advanced age and chronic lung disease might contribute to these adverse events.