Randomized Study Comparing the Use of Epidural Analgesia to Intravenous Narcotics for Laparoscopic Colorectal Resection.

Laparoscopic colorectal surgery has now become the standard of care in the treatment of many colorectal pathologies. In comparison to open or conventional surgery it has the benefit of decreased length of hospital stay (1), reduced postoperative pain, earlier return of bowel function (2,3) , earlier return to normal activities and improved cosmetic results.

Several criteria must be met before patients are discharged from the hospital. These discharge criteria are the same objective criteria we use to discharge our surgical patients:

1. Return of bowel function (as manifested by passage of flatus or bowel movement)
2. Ability to tolerate a regular diet
3. Stable vital signs for 24 hrs
4. Good pain control on oral medications
5. Ability to void freely
6. Return to a similar level of preoperative functioning

All attending surgeons will strictly adhere to the above 6 criteria when discharging patients.

Poor pain control is known to increase the length of hospital stay after surgery. Good pain control thus becomes essential in order to decrease the length of hospital stay and make patients more comfortable.

Pain control has been traditionally achieved through the intravenous route with the use of narcotic and non-narcotic medications. Postoperative pain is mainly incisional in nature and is due to enhanced responses to mechanical and thermal stimuli in the area of incision (6). Despite the fact that laparoscopic surgery is done through smaller incisions, several of these incisions are required to place the different trocars needed to safely perform the procedure. These incisions still cause a significant amount of pain and discomfort.

Opioid narcotics delivered systemically through the intravenous route are well known for their side effects, which range from mild nausea to opioid-induced bowel dysfunction (6). They are also known to prolong postoperative ileus by blocking coordinated bowel motility after surgery. The pathophysiology of ileus is multifactorial and incompletely understood. Major mechanisms contributing to ileus include surgical stress from physical manipulation of the bowel, secretion of inflammatory mediators, changes in fluid balance, hormones and electrolyte concentrations (7). Postoperative ileus can take several days to resolve and every effort should be made to help the bowel regain its function. This includes judicious use of IV fluids, correcting electrolyte abnormalities and finding the right balance between adequate pain control and delivering the right amount of intravenous pain medications. Controlling postoperative pain in an adequate manner without substantial systemic side effects becomes of primary importance. One way would be through the use of epidural analgesia where local anesthetics are injected through a catheter placed into the epidural space. The injection can cause both a loss of sensation and a loss of pain, by blocking the transmission of signals through nerves in or near the spinal cord while preserving motor function. The epidural space is the space inside the bony spinal canal but outside the membrane called the Dura mater. Thus there is no contact with the cerebrospinal fluid and the spinal cord itself.

Several trials of epidural analgesia in colorectal surgery patients have demonstrated the potential benefits of this technique such as decreased postoperative pain (8-10,12,14-18), faster return of bowel function with faster resolution of ileus (8,9,12, 14, 16,17) as well as a decreased incidence of nausea (17). These trials also showed that patients using epidural analgesia required less pain medications (10,11). A retrospective review from Sweden demonstrated a reduction in mortality after epidural anesthesia in patients undergoing rectal resection (19).

However, the results of these reports concerning length of hospital stay, cost and quality of life have been inconclusive. Most of the trials conducted until now have been very small with no more than 39 patients in each arm in the largest trial (9-17). The only study that showed a decreased length of hospital stay consisted of a cohort of 22 patients compared to a "historic" standard group (12). This study was small and non-randomized (12). The remaining studies, despite being randomized, were again small and thus have failed to show a decreased length of hospital stay in patients receiving epidural analgesia as compared to intravenous analgesia (9-11, 13-15, 16). The hypothesis advocated by some was that if the epidural decreases postoperative pain and allows for a faster recovery of bowel function then it should decrease the length of hospital stay. On the other hand, epidurals are usually left in place for 2-3 days following surgery before patients are transitioned to different forms of pain medications. This transition might in fact take time and actually increase the length of hospital stay thus potentially adversely affecting hospital costs. In addition, all the studies conducted until now have failed to adequately assess quality of life in patients receiving EA after laparoscopic colectomy.

Other measures that have been shown to reduce length of hospital stay and opioid induced side effects are with the use of alvimopan which is a peripherally acting μ-opioid receptor antagonist, recently approved for the reduction of postoperative ileus after colectomy. Alvimopan was associated with reduced ileus-related morbidity compared with placebo, without compromising opioid-based analgesia in patients undergoing surgery (20-21). Thus the use of alvimopan may obviate advocating the use of EA solely to reduce opioid-induced ileus.

This is a large prospective randomized trial recruiting 160 patients in each arm: an epidural arm and a conventional analgesia one. The trial will be performed in adult patients undergoing elective laparoscopic colorectal surgery for both benign and malignant conditions at the University of California, Irvine (UCI). The primary end point of the study would be to show a difference in length of hospital stay of one day between the 2 groups, and the secondary end points would be to show a decreased incidence of pain, earlier return of bowel function, earlier ambulation, better quality of life, less incidence of complications and side effects in the epidural group. This will be the largest randomized trial looking at the use of epidural analgesia in laparoscopic colorectal surgery to be ever conducted. It will hopefully provide definitive answers regarding any difference in the length of hospital stay. It will also address issues related to cost-effectiveness as well as quality of life using validated questionnaires, points that were not addressed by previously published data.