A prospective, randomized, comparative trial evaluating respiratory depression during patient-controlled versus anesthesiologist-administered propofol-remifentanil sedation for elective colonoscopy

Background: Patient-controlled sedation (PCS) with propofol-remifentanil (PR) is associated with rapid sedation and recovery, but it is associated with a greater requirement for airway rescue than PCS with midazolam-fentanyl.

Objective: To demonstrate that respiratory depression associated with PR is more frequent during anesthesiologist-administered sedation (AAS) than during PCS.

Design: Prospective, randomized, open-label study.

Setting: Academic medical center.

Patients: Fifty patients undergoing elective colonoscopy.

Intervention: PCS or AAS using PR. All patients breathed 100% oxygen via an anesthesia mask with continuous spirometry and bispectral index (BIS).

Main outcome measurements: Respiratory rate and BIS.

Results: Colonoscopy was completed in all patients. No patient under PCS required airway rescue. Five patients under AAS required bag-mask ventilation to resolve Sao(2) (arterial oxygen saturation) less than 90% lasting longer than 30 seconds. The median BIS for the AAS group was 71.7 (range 61.06-82.34) and 88.1 (range 83.15-93.05) for the PCS group. Median respiratory rates were 5.97 (range 1.21-10.73) breaths per minute for AAS and 13.19 (range 9.54-16.84) for PCS. Respiratory rates less than 2 breaths per minute composed 28% of the procedure time for AAS, but only 5% for PCS. Patients under PCS had lower median predicted effect site concentrations for PR, but were able to achieve brief peak levels exceeding those with AAS. These differences were significant (P < .001).

Limitations: Potential for bias with AAS.

Conclusions: Patients undergoing colonoscopy with PR are significantly more likely to require intervention for hypoventilation compared with PCS. (

Clinical trial registration number: NCT00868920.).