Pre- Versus Post-Incisional Epidural Morphine: Higher Postoperative Pain Perception and Extra Morphine Consumption

Pre- Versus Post-Incisional Epidural Morphine: Higher Postoperative Pain Perception and Extra Morphine Consumption

Pre- vs. Post-Incisional Epidural Morphine: Higher Postoperative Pain Perception and Extra Morphine Consumption

Background and Objectives: Neuraxial administration of morphine is an effective way of controlling postoperative pain and reducing analgesic consumption. Several animal models have demonstrated that preemptive administration of neuraxial narcotics reduced pain while others revealed the induction of post-incisional hypersensitivity. There have been no consistent results in clinical setting either. This double blind, randomized study compared the effects of PRE- vs. POST-incisional administration of neuraxial morphine on postoperative pain perception and analgesic requirements over 48 hours following laparotomy for open colectomy under standardized general anesthesia. Methods: Twenty patients received epidural morphine (3 mg) pre-incision and saline after wound closure (MO1 group), and 20 patients received epidural saline before incision and morphine after wound closure (MO2 group). Postoperatively, all patients received boluses of morphine (1.5 mg) via intravenous patient-controlled analgesia (IV-PCA), and rescue doses of intramuscular diclofenac (75 mg) every 6 hours, as needed.

Epidural, Morphine, Preoperative, Postoperative, Analgesia, Tolerance, Preoperative, Postoperative Analgesia

On the day of surgery, patients were brought to the operating room (OR) where routine monitors were placed and an epidural catheter was inserted at the level of L3-4 to a distance of 10 cm. All patients received two injections via the catheter: one injection contained 3 mg morphine (MO), and the other contained normal saline (NS) of the same volume. Patients were randomized to receive either NS preoperatively and MO postoperatively or vice versa. The first injection was administered 40 minutes before initiation of surgery, and the second one was given 15 minutes after surgery ended. All epidural catheters were removed before the patients were discharged from the post-anesthesia care unit (PACU).

Subjective pain intensity, using a visual analogue scale (VAS) from 0 (no pain) to 10 (unbearable pain)

Inclusion Criteria: 1.adults scheduled for elective laparotomy and colon surgery with the duration of surgery expected to last for at least 2 hours. Exclusion Criteria: allergy to morphine, fentanyl, non-steroidal anti-inflammatory drugs or any of the intraoperative anesthetic medications use of opioids, sedatives or stimulants during 21 days prior to surgery, psychiatric illness congestive heart failure, respiratory failure, neuromuscular disease or presence of a chronic pain syndrome Pregnant women and patients unable to sign their own consent form