Opioid-Free Anesthesia in Morbid Obese Patients: Review Article

Abstract

Abstart Morbid obese patients are highly susceptible to postoperative respiratory depression and delayed recovery owing to the pathophysiological changes of the obesity and the increased sensitivity to opioids. Opioid-free anesthesia technique is a technique in which the opioids aren't administrated throughout any route with the use of non-opioid analgesics to maintain analgesia, satisfaction, and hemodynamic stability of the patients. Many agents that can be used as non-opioid analgesics as clonidine, dexmedetomidine, ketamine, lidocaine, magnesium, non-steroidal anti-inflammatory agents, gabapentin, pregabalin, and dexamethasone. Each one of them has a different mechanism of analgesia through its effect on the pain pathway. Opioid-free anesthesia is indicated mainly in morbid obese patients with increased risk of obstructed breathing. It has many advantages especially the improvement of recovery profile, avoidance of respiratory depressant effect of opioids, and avoidance of opioid use and opioid-induced hyperalgesia. Hypotension and bradycardia are common complications of OFA technique especially with the use of alpha-2 adrenergic receptor agonists. It is contraindicated in patients with increased risk of hypotension as hypovolemic patients, patients with ischemic heart disease, and patients with autonomic neuropathy. The use of OFA technique requires the presence of monitoring of the depth of anesthesia and expert anesthesiologists. Mulier, described a technique for OFA that depends upon the use of an infusion called mulimex which is composed of premixed 1-3 of dexmedetomidine, lidocaine, ketamine, magnesium, deep neuromuscular block, and titrated MAC of desflurane. Many other regimens of OFA technique were described by many authors as that of Sultana. Despite the growing use of OFA technique in many bariatric centers, no definite protocol has an evidence base as each center have its own protocol. For introduction of OFA technique into the era of evidence-based medicine, many clinical trials evaluating different regimens and medications are required.