Hemodynamic Effects of Opioid Free Anesthesia Versus Opioid Anesthesia on Adult Patients Undergoing Craniotomies for Supratentorial Tumors. Randomized Controlled Trial

Anesthesia for craniotomies can be very challenging because of the presence of periods of noxious stimuli that interposes with periods of little stimulation which makes hemodynamic control a little bit more complicated. Intraoperative episodes of hypertension during periods of intense stimulations and early postoperative hypertension may lead to serious complications as post craniotomy intracranial hemorrhage and vasogenic brain edema. Anesthetic techniques based on usage of high doses of potent opioid analgesics such as fentanyl and remifentanil have been widely popular among anesthesiologists. However, the intra operative use of large bolus doses or continuous infusions of potent opioids may be associated with postoperative hyperalgesia and increased analgesic consumption.

More recently, concerns have arisen about impaired healing,immunosuppression,and worsening of oncologic outcomes with systemic opioids. Another technique that started gaining its popularity is opioid free anesthesia (OFA) technique whose corner stone is depending on multiple anesthetic adjuvants that have analgesic effects, , therefore when given together in small doses they result in good anesthesia with less side effects and faster recovery compared with opioids. This technique has been successfully used in anesthesia for bariatric surgeries combining multiple drugs as dexmedetomidine, lidocaine, ketamine, ketorolac and magnesium.

Dexmedetomidine is a highly selective α2-adrenoceptor agonist with sedative, anxiolytic and analgesic properties that has minimal effects on respiratory drive. Although preoperative intravenous dexmedetomidine administration is associated with a reduction in postoperative pain intensity, analgesic consumption and nausea, the analgesic property of dexmedetomidine is less effective compared with opioids. Intravenous lidocaine has been described as having analgesic, anti-hyperalgesic, and anti-inflammatory properties. Intravenous lidocaine infusion in the perioperative period is safe and has clear advantages, such as decreased intra operative anesthetic requirements, lower pain scores, reduced postoperative analgesic requirements, as well as faster recovery. In addition to ketamine magnesium is also reported to enhance analgesia by blocking NMDA receptor, also magnesium has the properties of a sympatholytic and has been introduced as a safe component of balanced anesthesia.

This comparative study between Opioid free anesthesia (OFA) and Opioid anesthesia (OA) aims to compare the effect of both techniques on intra operative hemodynamics, intracranial tension and recovery in cranial surgeries for supratentorial tumors.

After obtaining an informed written consent from the patients or their responsible relative, patients will be divided into 2 groups randomly using computer software (research randomizer.org); Opioid free Anesthesia group (OFA) and Opioid Anesthesia group (OA). To assure blindness, numbers will be concealed by closed envelope, analgesic infusions will prepared by a clinical pharmacist not included in data collection and the attending anesthetist will be blinded to the type of analgesic solution injected.