Opioid Free Versus Opioid Balanced Anesthesia

After approval of the Ethical Committee of Faculty of Medicine, Alexandria University and having an informed written consent from every patient included in the study, the present study will be carried out in Alexandria Main University Hospitals on sixty adult patients belonging to ASA class I or II scheduled for middle ear surgery under general anaesthesia.

(The sample size is approved to be sufficient by the Department of Statistics, Medical Research Institute, University of Alexandria).

Inclusion criteria:

• Patients of either sex.
• American Society Anesthesiologists' physical status I-II.
• Age between 18 and 50 years. Exclusion criteria:(depend on table 1)
• Patients with gastrointestinal disease.
• A history of motion sickness, or a previous episode of PONV.
• Patient received any opioid, steroid, or antiemetic medication within 72 h before surgery.
• Those who were pregnant or menstruating.
• History of opioid or drug abuse. METHODS Patients will be randomly allocated into two equal groups (thirty patients each) using the closed envelope method.

I will compare postoperative nausea and vomiting (PONV) in patients scheduled for middle ear surgery. Sixty patients will be randomly allocated to receive either balanced anaesthesia (group A) using fentanyl, propofol and isoflurane, or opioid free anaesthesia (group B) using propofol and isoflurane. Pain scores, nausea ⁄ vomiting scores, conditions for surgery and analgesic requirements will be recorded post operatively.

Anaesthetic management Preoperative management

All patients will be visited before surgery to be clinically assessed and the preoperative surveillance includes:

• Haematological screening (Complete blood picture, Serum electrolytes).
• Standard coagulation studies e.g. prothrombin time, international normalized ratio (PT-INR).

On arrival to the operating room and before anaesthetic induction all patients will be monitored by the standard routine monitoring, which include:

• A 5-lead electrocardiography.
• A non-invasive blood pressure (NIBP) (mmHg).
• Pulse oximetry (%).
• Capnography. (End Tidal CO2 pattern and value in mmHg).
• Temperature monitoring. A peripheral intravenous cannula of 20 gauges will be inserted in a dorsal vein of the non-dominant hand.

Premedication with Midazolam in a dose of 0.02mg/ Kg will be used. Induction Preoxygenation with 100 % O2 for 3 minutes. General anaesthesia will be induced by propofol (2 mg/kg) and atracurium (0.5 mg/kg) intravenously guided by a nerve stimulator, followed by endotracheal intubation after loss of train of four.

All the patients will receive i.v. acetaminophen (1000 mg) _20 min after induction and i.v. ketorolac (30 mg).

Local analgesia will be injected by surgeon. All patients will receive beta blocker (Inderal 1mg) and magnesium sulphate (15-30mg/kg) for achieving hypotensive anaesthesia.

Maintenance Maintenance of general anaesthesia with a mixture of isoflurane (1MAC) and oxygen.

All patients will be mechanically ventilated with an anaesthesia machine to keep SpO2 > 95% and end-tidal CO2 between 35-45 mmHg.

Additional atracurium will be administrated as appropriate in bolus doses if needed.

Group A Fentanyl (1mg/kg i.v.) will be administered before general anaesthesia (GA). GA will be maintained with inhalation anaesthetics (isoflurane) at a minimum alveolar concentration of 0.7-1.3.

Group B Opioid free anesthesia (syringe of saline is given instead of fentanyl) and the same general anesthesia is given as group A(muscle relaxant ,propofol, inhalation for maintance).

Recovery At the end of surgery, isoflurane will be discontinued, 100% oxygen will be given, all patients will be planned for extubation in the operating room depending on recovery criteria after complete reversal of muscle relaxant with neostigmine (up to 5 mg).

Tracheal extubation will be performed in a semi- sitting position after fulfilling the criteria for extubation. Extubation criteria include: a fully conscious patient, haemodynamic stability, reversal of neuromuscular blockade, TOF ratio 0.9 - 1 on nerve stimulator, and the ability of head lift for 5 seconds.

Postoperative multimodal pain management Postoperative pain will be treated with i.v. acetaminophen (1000mg) and i.v. ketorolac (30 mg) every 6 h for the first 24 h. Postoperative pain will be measured on an 11-point numeric pointscale (NPS).

management of PONV Dexamethasone (8 mg i.v.) will be administered during induction, ondansetron (4 mg i.v.) and metoclopramide (10 mg i.v.) post operative if Patients complaining of PONV after discharge from the PACU.

Measurements

1. Demographic data: Age (years), sex, weight (kilograms).
2. Hemodynamic parameters:

• Pulse oximetry (%)
• Heart rate (HR). Beats/minute
• Mean Non-Invasive arterial blood pressure (NIBP) (mmHg)

1. Pain assessment The level of pain will be assessed on an 11-point NPS. Patients will be asked to determine their own 'acceptable' pain score. The 11-point numeric scale ranges from '0' representing no pain extreme to '10' representing the other pain extreme (worst pain imaginable).(8)
2. Nausea and vomiting assessment (table2,3) Patients will be asked to rate the worst episode of PONV on a four-point verbal rating scale (VRS) (none, mild, moderate, or severe). Patients were also will be asked whether they experienced retching or vomiting.
3. Sedation assessment

Sedation score:

1. Alert
2. Mild, drowsy, easy to awake
3. Moderate, easy to arouse
4. Severe: somnolent difficult to arouse
5. Sleeping The Sedation score will be documented at 0, 1, 2, 4, 6, 12, 18, and 24 hours.
6. Satsifacation of patient assessment by QoR40 questionnaire The QoR-40 is a global measure of quality of recovery. It incorporates five dimensions: patient support, comfort, emotions, physical independence, and pain; each item is graded on a five-point Likert scale. QoR-40 scores range from 40 (extremely poor quality of recovery) to 200 (excellent quality of recovery).(29) Timing Hemodynamic (blood pressure, pulse) of Patients will be assessed during the surgery every 10 minutes and at 1 and 2 h after the end of surgery and at discharge from the day unit. At each of these times, the nurse recorded the incidence and worst severity of pain, nausea and emesis since the last evaluation using the same criteria as before. Any medication will be given for pain or nausea (administered for moderate-severe symptoms, or at patient request) will be also recorded, till the time of discharge. Patients will be discharged with medication comprising slow-release ibuprofen. The following day, the researcher will telephone the patient to assess the incidence and worst severity of pain, nausea and emesis since discharge and whether any analgesia or antiemetics will be taken. Patients will be also asked to record their satisfaction with the control of pain, the control of sickness and their overall day surgery experience on 11-point (0-10) verbal rating scales.