A Randomized Controlled Study of the Effect of Intraperitoneal Ropivacaine on Visceral Pain After Laparoscopic Gastrectomy

Postoperative pain is a common adverse reaction after laparoscopic gastrectomy. Insufficient analgesia can cause severe stress response,affect the recovery of postoperative gastrointestinal function, increase the incidence of postoperative complications and prolong the length of hospital stay. Although laparoscopic surgery significantly reduces postoperative pain compared to traditional open surgery, the management of postoperative pain remains a challenge. Postoperative pain after laparoscopic surgery is mainly divided into three parts: incision pain(somatic pain component), deep abdominal pain (visceral pain component) and shoulder pain (referred pain component). In a prospective study, Blichfeldt-Eckhardt et al. found that visceral pain accumulated in the first week after surgery was identified as an independent risk factor for unexplained chronic pain at 12 months after surgery, and visceral pain was the only pain component that was independently and significantly associated with chronic unexplained pain at 12 months after surgery .

Visceral pain is generally defined as pain caused inside the body, but is usually caused by excessive contraction, stretching, or ischemia of the walls of internal organs . In contrast to pain signals originating from the skin,pain originating from the viscera is described as dull and diffuse, often poorly localized, and can be distant from its origin.Visceral pain is considered more unpleasant and frightening than somatic pain.

Therefore,relieving the visceral pain is of great significance for patients' postoperative emotional experience, functional recovery and reducing the formation of long-term chronic pain. However, there is no clear clinical consensus on relieving visceral pain by now, so effective clinical methods to relieve visceral pain need to be explored urgently.

Intraperitoneal spraying local anesthetics is a simple and inexpensive method, which has been proved to be a safe and effective way to reduce the use of opioid and postoperative pain score in randomized controlled trials and Meta-analysis of various surgical types such as laparoscopic cholecystectomy , laparoscopic appendectomy , laparoscopic gynecology and so on. Intraperitoneal spraying local anesthetics is a type of topical anesthesia.Local anesthetics produce local anesthesia by acting on nerve endings on the surface of the visceral organs.Visceral organs mainly transmit nociceptive signals through the vagus nerve and spinal nerve, among which the spinal nerve mainly transmits mechanical stimulation signals, while the vagus nerve mainly transmits chemical stimulation signals. Arman Kahokehr et al. found that intraperitoneal spraying local anesthetics during colectomy may reduce postoperative pain by blocking intra-abdominal vagus nerve signals. At the same time, it inhibits the corresponding neuroendocrine stress pathway, thus resulting in behavioral benefits. However, it does not separately evaluate the different pain components of patients after surgery.

At the same time,the effect of intraperitoneal spraying local anesthetics is still controversial and many studies lack evaluation of postoperative recovery quality,so this technique has not been widely used in clinical practice. Schipper IE et al. spray 20ml 2.5% bupivacaine into the abdominal cavity during laparoscopic gastric bypass surgery, and the test results indicated that the experimental group did not significantly reduce postoperative pain or opioid use, and the use of antiemetic drugs and the length of hospital stay were not significantly reduced.A review in 2021 included 85 clinical trials of intraperitoneal spraying local anesthetics during laparoscopic cholecystectomy, found that intraperitoneal spraying local anesthetics could reduce pain for up to 24 hours in patients undergoing laparoscopic cholecystectomy. However,none of these trials provided postoperation follow-up information and evaluation of postoperative recovery quality.