This study will be conducted in Cairo University Hospitals at Uorolgy OR. This study will
include 40 patients divided into two groups, aged 18 to 65 years, both sexes, belonging
to the American Society of Anesthesiologists (ASA) physical status I, II undergoing
simple nephrectomy.
Inclusion criteria
Exclusion criteria
Patient refusal.
Patients with a history of allergic reactions to melatonin.
Patients receiving drugs with known analgesic and sedative properties.
Body Mass Index (BMI) over 30 kg/m2.
Drug or alcohol abuse.
History of cardiovascular disease.
Renal Failure.
Mental impairment.
Renal impairment.
Medical and surgical history of the patients will be taken, clinical examination of the
patients will be performed and routine laboratory investigations as CBC, coagulation
studies, renal function and liver function will be done.
Preoperative visit will be conducted the day before surgery. All patients will be
evaluated by the same anesthesia resident, who provided information on the preoperative
course and instructed them on the procedure.
Each patient will be instructed about postoperative pain assessment with the visual
analog scale (VAS) which [0 represents "no pain" while 10 represents "the worst pain
imaginable"] and level of anxiety.
Intraoperative management All patients will be connected to standard monitoring which
include electrocardiography (ECG), non-invasive arterial blood pressure (NIBP), pulse
oximetry, temperature probe, and capnography (will be connected after induction of
general anesthesia).
Induction of general anesthesia will be done after inserting 20G venous cannula by IV
propofol 2-2.5 mg / kg and IV fentanyl 2ug / kg. After IV Atracurium 0.5mg / kg,
endotracheal intubation will be done.
Maintenance of anesthesia will be isoflurane (1-1.5%) with 50-100% oxygen. Incremental
doses of IV Atracurium 0.1mg/Kg will be given every 20 min. Patients will be mechanically
ventilated and end-tidal CO2 will be maintained between 35-45 mmHg.
Additional fentanyl bolus dosages of 1 µg/kg IV will be administered if heart rate or
mean arterial blood pressure elevated more than 20% of the baseline (after exclusion of
other causes than pain).
At the end of the surgery, inhalational anesthetics will be stopped waiting for motor
power and conscious level to be regained. Then the reversal will be given IV Neostigmine
0.03-0.07 mg/kg + Atropine 0.02 mg/kg.
A standardized analgesic regimen will be prescribed in the post-operative period. All
patients will receive paracetamol 1 gm every 6 h as routine analgesia.
Rescue analgesia of morphine will be given as 3 mg bolus if the VAS > 3 to be repeated
after 30 min if pain persists until the VAS < 4. VAS will be assessed at 0, 2, 4, 6, 8,
12, 18, and 24 h postoperatively. The adverse effects will be assessed: hypotension
(decrease in basal mean arterial blood pressure by 20%) will be treated with I.V. fluid,
bradycardia (defined by decrease in basal heart rate by 20%) will be treated by I.V.
atropine 0.02 mg/kg, respiratory depression (the SpO2 < 95% and need O2 supplementation),
and 4 mg of ondansetron every 6 hours will be administered for postoperative
nausea/vomiting (PONV) as required.