Patient-controlled analgesia versus oral controlled-release oxycodone - are they interchangeable for acute postoperative pain after laparoscopic colorectal surgeries?
BACKGROUND
Standard therapy for postoperative pain after laparoscopic colorectal surgeries at the Tan Tock Seng Hospital consists of intravenous morphine via patient-controlled analgesia (PCA) for the first 24-48 h, followed by oral analgesics. We compared the efficacy and safety of oral controlled-release (CR) oxycodone hydrochloride (OxyContin tablets) and PCA after laparoscopic colorectal surgeries.


METHODS
Between March and August 2006 (phase 1 study), 14 patients underwent laparoscopic colectomy, laparoscopic hemicolectomy or laparoscopic-assisted anterior resections. All patients were on oral CR oxycodone with oral immediate-release oxycodone on an as-needed basis for breakthrough pain. Pain intensity, analgesic use, length of hospital stay and side effects were evaluated. These were compared to data obtained from a second study of a similar design where 9 patients underwent similar operations from October 2006 to July 2007 (phase 2 study) and were on PCA morphine.


RESULTS
All patients in the CR oxycodone and PCA morphine groups needed the opioid medication for only 2 days. There was no difference in mean (range) postoperative pain intensity scores between patients on oxycodone and those on PCA morphine for the 1st postoperative day [2.07 (0-5) vs. 2.78 (2-4) on a Visual Analogue Scale (VAS) from 0 to 10; p = 0.10] and the 2nd postoperative day [1.14 (0-2) vs. 1.67 (0-3); p = 0.10]. Generalized estimating equations with linear link function confirmed that there was a significant relief of pain in patients after operation. On average, the VAS score of pain was 1.00 units lower on day 2 when compared with day 1 (p < 0.01). The mean (range) doses of oxycodone used on the 1st and 2nd postoperative day were 13.57 mg (10-30) and 15.36 mg (10-30), and the mean (range) doses of morphine used on the 1st and 2nd postoperative day were 14.9 mg (8-28) and 16.3 mg (4-31), respectively. Incidence of nausea and vomiting was 14.2 and 20% for the CR oxycodone and PCA groups, respectively.


CONCLUSIONS
Oral CR oxycodone 20 mg per day is a cheaper, convenient and an efficacious alternative analgesic to PCA opioids after laparoscopic colorectal surgery.
Ho
Hwee Shih
HS
Mount Alvernia Hospital, Singapore. hohweeshih@yahoo.com.sg