Patient-controlled analgesia for conscious sedation during colonoscopy: a randomized controlled study

Background: The aim of this study was to assess whether patient-controlled anesthesia (PCA) can improve patient tolerance for colonoscopy. We compared baseline sedation and analgesia with baseline sedation and PCA. Methods: Fifty-six consecutive patients were alternatively allocated to 1 of 2 groups: either to control group (n = 28) to receive standard sedation (meperidine and midazolam as baseline and additional doses of meperidine administered by the anesthesiologist) or to a PCA group (n = 28) to receive the same baseline premedication but additional analgesia with meperidine being self-administered. Cardiopulmonary parameters were recorded and tolerance for the examination was evaluated by a numeric rating scale, 0 meaning "no pain" and 10 meaning "maximal pain." Results: Patients' mean pain score (on a scale of 0 to 10) was 4.85 +/- 3.74 for the PCA group and 5.30 +/- 3.53 (not significant) for the control group. Physicians' assessment of patient tolerance registered a lower numeric rating score than patients' assessment. The duration of the procedure was slightly longer in the PCA group. None of the patients experienced a decline in oxygen saturation below 90%; a decrease in expiratory carbon dioxide during the examination was noted in both groups of patients, particularly during the first minutes of the examination. Mean additional sedation per patient in the PCA group was slightly higher, but not significantly different. Conclusions: Our results suggest that patient-controlled analgesia during colonoscopy is as effective as standard sedation with respect to patient tolerance and safety of the examination.