Effect of Opioid-sparing Anesthesia on Quality of Recovery After Emergency Laparotomy

Upon arrival to the operating room, routine monitors will be applied; intravenous line will be secured, and 8 mg dexamethasone will be slowly administrated. Baseline preoperative blood pressure will be recorded as the average of three readings with difference less than 5 mmHg.

Preoperative fluid management Fluid responsiveness will be defined as a 10% increase in stroke volume after passive leg raising maneuver. Fluid responder will be given 500-mL bolus of lactated ringer. Passive leg raising will be repeated until wither the patient is non-responder or 1500 mL were infused.

induction of anesthesia: 2 mg/kg propofol and 1 mg/kg succinyl choline. Anesthesia will be maintained by isoflurane in air/oxygen admixture (with target end tidal isoflurane 1-1.2%). Atracurium will be administered after patient recovery from succinylcholine at a dose of 0.5 mg/Kg and then regularly according to local protocols.

A 10-12 mL/kg/hr of lactated ringer will be infused during the procedure. Heart rate and blood pressure will be monitored at 2 min intervals. The average of every 5 successive readings would be recorded every 10 min. If patients developed hypotension (mean arterial pressure (MAP) ≤ 70% of the baseline reading and/or \<65 mmHg), a fluid bolus of 4 mL/kg will be given and the change in the pulse pressure will be noted. If the pulse pressure increases by \>10 %, the fluid bolus will be given until the increase in pulse pressure is \<10%. If hypotension persists despite the adequate volume replacement a 5-mcg bolus of norepinephrine will be given. The bolus will be repeated if MAP was not restored within 2 min. Infusion of norepinephrine can be given if MAP persisted \<65 mmHg despite 5 boluses of norepinephrine.

If bradycardia occurred (defined as heart rate less than 55 bpm), it will be managed by IV atropine bolus (0.5 mg).

Intraoperative tachycardia and/or hypertension (defined as 20% increase from the baseline value) will be managed by fentanyl bolus of 0.5 mcg/kg, in absence of other causes.

At the end of the procedure, all patients will receive 1 gm of paracetamol intravenously and local infiltration of the wound with 40 mL of 0.125% bupivacaine. Patients who are not indicated for extubation at the end of the surgery will be excluded from the study.

Postoperative management All patients will receive 1 gm/ 6h of paracetamol. Static (at rest) and dynamic (during cough) numerical rating scale (NRS) will be assessed at 0.5, 2, 6, 10, 16, 24 hr postoperatively. If the NRS\>3, a 2 mg morphine bolus will be given to be repeated after 30 min if pain persists.

4 mg of ondansetron will be given if patients developed nausea or vomiting.

• intraoperative fentanyl consumption [Time frame: from time of induction of anesthesia until end of procedure]
• mean arterial pressure [Time frame: at baseline preoperatively, every 10 minutes (averaging of each 5 readings) from induction of anesthesia until end of procedure, and 2, 6, 10, 16, 24 hours postoperatively.]
• heart rate [Time frame: at baseline preoperatively, every 10 minutes (averaging of each 5 readings) from induction of anesthesia until end of procedure, and 2, 6, 10, 16, 24 hours postoperatively.]
• postoperative opioid consumption [Time frame: from extubation until 24 hours postoperatively]
• numeric rating scale [Time frame: 30 minutes, 2-, 6-, 10-, 16-, 24 hours postoperatively]
• serum lactate [Time frame: 30 minutes postoperative]
• respiratory rate [Time frame: 30 minutes postoperative]
• Oxygen saturation/ fraction of inspired oxygen (SF ratio) [Time frame: 30 minutes postoperative]