Fentanyl Versus Dexmedetomidine as an Adjuvant to Bupivacaine in Spinal Anesthesia ; Peritoneal Symptomatic Effects

Acute appendicitis is among the most common causes of lower abdominal pain leading patients to attend the emergency department and the most common diagnosis made in young patients admitted to the hospital with an acute abdomen .

In intracavitary abdominal surgery (e.g. Appendectomy),general anesthesia is conventionally chosen as it provides a higher safety profile with respect to the risk of aspiration, abdominal discomfort, and better exposure secondary to muscle relaxation however, at present it is considered safe to do spinal anesthesia in various abdominal procedures, even where significant muscle relaxation is required in certain complex cases such as peritonitis many patients with complicated conditions were operated under spinal anesthesia, which did not significantly interfere with surgical technique or exposure. Additional advantages of spinal anesthesia include faster recovery, better oral tolerance, and shorter hospital stay compared to general anesthesia.

The Covid-19 pandemic currently affects almost every aspect of healthcare. The risk to the operating room team from the contaminated aerosols produced by intubation and positive pressure ventilation may be reduced by performing suitable open operations with neuraxial anaesthesia instead of General anesthesia .

Neuroaxial anesthesia is commonly preferred for surgeries of lower abdomen, perineal and lower limb. It is easy to administer and very economical but needs skills. Intrathecal local anesthetics are limited by short duration of action and needs early use of rescue analgesia postoperatively. Adjuvants are added to improve quality and duration, provide better postoperative analgesia and patient comfort.

A common problem during abdominal surgeries under spinal anesthesia is peritoneal related symptoms as visceral pain, nausea, vomiting, vagal symptoms like bradycardia and hypotension.

Many adjuvants like fentanyl, morphine, ketamine, neostigmine, and clonidine are being used to prolong the analgesic effects of local anaesthetic for many years. These drugs including opioids are usually results in several side effects include itching, decrease respiratory rate, difficulty in urination, postoperative gastrointestinal disturbance which can be overcome by preferring them as adjuvant with other analgesics.

Intraoperative peritoneal related symptoms as visceral pain, nausea, vomiting, vagal symptoms like bradycardia and hypotension are a common problem and there are some intrathecal adjuvants can solve these symptoms.

Fentanyl is µ receptor agonist 80 times more potent than morphine as an analgesic added to spinal 0.5% heavy bupivacaine improves quality of spinal analgesia, reduces visceral and somatic pain. However, their addition may have side effects like pruritus, respiratory depression, urinary retention, postoperative nausea and vomiting which limits their use.

Dexmedetomidine is highly selective α2-agonist, S-enantiomer of veterinary sedative medetomidine. Food and Drug Administration has approved its use for short-term ICU sedation, it is reported to provide sedation that parallels natural sleep, anxiolysis, analgesia, sympatholytic, and anaesthetic-sparing effect with minimal respiratory depression. α2- agonists produce clinical effects.

It was reported in a previous study that intraoperative dexmedetomidine can reduce the incidence of postoperative nausea and vomiting (PONV)in patients undergoing thoracic surgery and a dose-response relationship between intraoperative dexmedetomidine and PONV was Observed; and the optimal dose range for antiemetic effects of PONV is 50-100 μg. Previous small Some meta-analyses demonstrated that intraoperative dexmedetomidine significantly lowered post-operative pain scores and opioid consumption, which could lead to a reduced opioid-related adverse events, including PONV.

Dexmedetomidine prevents and reduces peritoneal related symptoms Intraoperative, and it can significantly lower the demand for opioids and inhalation anesthesia during and after operation, which could help to reduce opioid-related adverse events, including PONV.