Adequate analgesic regimen would be required after minimally invasive colorectal surgery

To the editor: Postoperative pain management is important not only in patient wellbeing, but in recovery. An appropriate strategy for pain management is required in the perioperative period. We read with interest the article on the necessity of intravenous patient controlled analgesia (IV-PCA) in patients undergoing mini mally invasive colorectal surgeries [1]. The authors suggested that IV-PCA may not be necessary in patients who underwent minimally invasive surgeries for colorectal cancer, because there were no significant differences on postoperative analgesia between opioid-based IV-PCA and intravenous tramadol on demand. However, we cannot agree with their conclusion on some points. First, all patients in their study had suffered extremely severe pain at postoperative days 1 and 2. According to the methods of this study, the authors aimed to maintain scores less than visual analogue scale (VAS) 4 on a 10-point VAS, but the aim was not achieved and they failed to provide adequate analgesia for all patients during postoperative periods. It's especially surprising that even the patients who had received IV-PCA treatment had suffered severe pain during postoperative periods. The main purpose of PCA is literally analgesia, but the IV-PCA regimen in this study failed to provide adequate analgesia. The main cause of inadequate analgesia in IV-PCA group was insufficient dosage of fentanyl, and inappropriate IV-PCA regimen. IV-PCA regimens consist of several variables, including the bolus dose, lockout time, and maintenance infusion. These variables can affect the analgesic efficacy of IV PCA. Usually, the recommended IV-PCA regimen of fentanyl is 10–20 mg for bolus dose and 4–10 minutes of lockout interval [2]. Use of continuous maintenance infusion was not recommended for fentanyl IV-PCA. In their study, the PCA formulation contained 25 mg/kg fentanyl diluted to 100 mL in normal saline. The bolus volume was 0.5 mL with 10 minutes of lockout interval, and the maintenance rate was set at 0.5 mL/hr. For example, a patient weighing 50 kg received 6.25 mg of fentanyl as bolus dose with a maintenance rate of 6.25 mg/hr of fentanyl according to their IV-PCA regimen. Compared with the recommended regimen, the regimen in their study might be insufficient to provide adequate analgesia for their patients. Second, their pharmacologic effect of tramadol may affect the results of the study. The authors said that tramadol is an anti-inflammatory drug, but it is not. Tramadol is a synthetic opioid that has weak m agonist activity and inhibits reuptake of sero …