Intraperitoneal Atomization of Ropivacaine During Gynecologic Laparoscopic Surgery: Impact on Pain, Opioid Use and Length of Recovery Room Stay

Introduction:

Laparoscopic surgery has replaced open surgical techniques for a large number of abdominal general surgical and gynecologic interventions. However pain following laparoscopic surgery continues to be a clinically important problem with 80% or more patients requiring opioid analgesia post-operatively to control their pain. Post-operative pain and to a lesser extent post-operative nausea and vomiting (PONV) are the main factors leading to delayed discharge from the surgical recovery room and from the hospital following most surgical cases. Hence, post-operative pain and PONV lead to increased costs of care. By reducing these surgical complications patients can be discharged from the recovery room more rapidly leading to reduced resource utilization and expense. This is especially true for routine surgical cases (laparoscopic cholecystectomy -gallbladder removal, gynecologic procedures, gastric surgery) that have the potential for same day surgery and discharge to home if their pain can be adequately treated. It also applies to inpatient cases where superior pain control and less PONV require less nursing care and potentially earlier discharge.

The origin of pain after laparoscopic surgery is multifactorial with pain arising from the incision site, direct trauma in the area of surgical dissection, peritoneal micro-tears and inflammation due stretching during insufflation and peritoneal and diaphragm irritation of from the residual CO2 remaining after the pneumoperitoneum is deflated. Because this pain is multifactorial - a multifactorial approach is needed. Although the somatic pain associated with the abdominal wall incision responds well to nerve blocks or opiate medications, visceral pain due to pneumoperitoneum induced stretching, compression, oxygen deprivation and inflammation during the surgery is less responsive to these interventions. However, visceral pain can be treated by topical anesthetics sprayed directly onto the nerve endings of the visceral peritoneal lining and diaphragm surface. This knowledge has resulted in extensive research studying the effects of applying topical anesthetics to the peritoneal surface during laparoscopic surgery in an effort to reduce post-operative pain and its attendant complications. Fairly clear conclusions can be drawn from review of the research investigating topical anesthetic application to the peritoneum, diaphragms and surgical site: they effectively reduce postoperative pain and opioid use. They do not have any of the adverse effects of systemically administered opioids such as sedation, respiratory depression, nausea, or GI dysmotility. They are safe and relatively inexpensive. Their use results in earlier progression to ambulation, less shoulder tip pain, less post-operative nausea and vomiting, earlier discharge from the recovery room and in some studies earlier discharge from the hospital.

Despite this research and international recommendations to use this therapy topical anesthetic application during laparoscopic surgery is not routinely used by most general or obstetrical surgeons. There are probably two inter-related reasons for this lack of adoption of this simple concept. First, no simple method exists for delivering topical anesthetics to the peritoneal surface. Most studies diluted the drug with large volumes of saline (making it less potent and less likely to work), then injected it into a trocar where gravity took the solution straight into the gravity dependent gutters. This type of delivery system would not be expected to optimize results of any topically active medication since the majority of the peritoneal surface is never exposed to the anesthetic. Secondly, the pain reductions reported in most topical anesthetic studies were positive but not impressive enough for surgeons to change practice. This marginal reduction in post-operative pain is probably due to these poor delivery systems with non-directed application of the drug and the great variations in drug concentrations, site of delivery, and timing of application. Studies that used more directed spray seem to show better results. A 2010 metaanalysis concludes that future studies should not be designed to determine if topical intraperitoneal local anesthesia is effective (this is already proven), rather this research should focus on optimization of the method of delivery (aerosolized), location of application, timing of drug delivery, and drug dose and concentration.

This study is designed to address these issues. The investigators will use topical anesthetic (namely 0.25% ropivacaine) delivered directly onto the target sites both at the beginning and the end of surgery. The drug will be delivered using an inexpensive delivery system that will direct a fine mist of drug directly to the areas of the peritoneal cavity that are theoretically the cause of post-op pain (diaphragms, peritoneal abdominal surface, surgical dissection site). Our primary goal is to assess the efficacy of intraperitoneal topical anesthesia in reducing postoperative pain, opioid requirements in patients undergoing laparoscopic gynecologic laparoscopic procedure for uterus or adnexal benign pathology.