This research is done to examine the effect of N-acethylcystein on postoperative pain after laparascopic cholecystectomy. This research is randomized double blind controled clinical trial. Thirty patients with this inclusion criteria: 20-50 years old; candidate for laparascopic cholecystectomy; with ASA1(healthy patient without other disease)
are selected and randomly divided in two groups.
Exclusion criteria include previous abdominal surgery; known sensivity to N-acethylcystein; operation time more than two hours; any uncommon complication in surgery or in intubation; neuropsychiatric disease; chronic pain before surgery; addiction; pregnancy; lactation and other concurrent surgery.
The used substance is N-acethylcysteine, its chemical compound is Acetamido-3-sulfanylpropanoic acid (C5H9NO3S) and is acethylated derivative of L-cysteine amino acid.
The night before surgery, 1200mg oral N-acethylcysteine in the form of two effervescent tablets (600mg) dissolved in water, were given to the intervention group and the morning before operation, 3cc of intravenous N-cethylcystein(200mg/cc) that was equal to 600 mg, in 100cc normal saline in a 5 minute transfusion . The prescribtion duration is twice, the night before and the morning of surgery and no longer required to be prescribed.
For the control group, two vitamin c effervescent tablets (placebo) dissolved in water, were given at night before surgery and 3cc distilled water in 100cc normal saline as placebo transfused in 5 minutes in the morning before surgery.The liquid volume in all syringes specified as number 1 and number 2 with 3cc fluid, only the researcher's colleague knows about this and to avoid observer bias, in double-blind study. The anesthesia plan is similar in all of the cases including premedication, induction, antiemetic (plasil), volatile anesthetics and administration of morphine (1mg/kg). Mechanical ventilation is set to low tidal volume (6-8 cc/Kg) and high respiratory rate (14-16/minute) to prevent chest pain(confounding factor) caused by ventilation of small lung. Small lung in laparascopy is induced by insufflation of Co2 into the abdominal cavity and its resulted low lung functional residual capacity .
The blood pressure, heart rate, occurrence of nausea and vomiting and severity of pain (by visual analog scale) are evaluated during postoperative recovery consecutively 1, 2, 4, 8 and 12 hours after the surgery. The total amount of pethidine consumed within 24 hours after surgery in two groups is evaluated and compared. If the pain score is more than 5, 30 milligrams of pethidine is administered each 4 to 6 hours. The total duration of the study is 12 months.
Results: The study findings show a reduction of pain, the need for opioid and less side effects.
Other outcoms studied are The existing nausea, vomiting and blood pressure and pulse rate alterations after the surgery, in the above-mentioned intervals, and decrease the use of this drug to reduce pain and decline in using of pethidine.