Efficacy of Granisetron for Prevention of the Postoperative Nausea and Vomiting after Laparoscopic Surgery in Adults

Abstract

Summary P ostoperative nausea and vomiting are among the most distressing post-operative complications. Routine prophylaxis is becoming a growing demand and the choice of antiemetics is very broad. Prompt dealing with the multiple risk factors involved in PONV is also an important aspect of the problem. Physiology of Nausea and vomiting: Key structures and pathways identified are: • The chemoreceptor trigger zone in the area postrema which responds to circulating emetogenic neuro-transmitters, hormones, toxins and drugs. • The vomiting center in the reticular formation which coordinates the visceral and somatic components of the emetic reflex. Risk factors for PONV: I. Patient-related factors: A- Pre-existing patient factors: Female gender, history of PONV, motion sickness or migraine. B- Preoperative factors: Prolonged fasting, full stomach, anxiety and drugs like opioids. II. Anesthesia-related factors: Opioids, nitrous oxide, some intravenous agents like ketamine and volatile anesthetic agents. III. Surgery-related factors: Type and duration of surgery. IV. Postoperative factors: Dehydration, hypotension, hypoxia, early ambulation, early oral intake and pain. Prevention & treatment of postoperative nausea & vomiting: Drugs used for the symptomatic relief of nausea and vomiting include: • 5-HT3 receptor antagonists. • Dopamine receptor antagonists. • Muscarinic receptor antagonists. • Histamine H1 receptor antagonists. • Sedative and hypnotics. • Phenothiazines. • Corticosteroids. • Neurokinin1 (NK1) receptor antagonists. We studied 135 adult patients with the following inclusion criteria: ASA I and II physical status, aged (20-50 years) scheduled for laparoscopic procedure. Patients were randomly allocated into one of five groups:  Group I (G) n = 27 received equal volume of saline intravenously at the end of surgery.  Group II (G) n = 27 received 10/kg granisetron intravenously at the end of surgery.  Group III (G) n = 27 received 20/kg granisetron intravenously at the end of surgery.  Group IV (G) n = 27 received 40/kg granisetron intravenously at the end of surgery.  Group V (G) n = 27 received 80/kg granisetron intravenously at the end of surgery.

Exclusion Criteria included: 1. Patients who had gastrointestinal disease. 2. Patients who had a history of motion sickness, inner ear problems and/or previous PONV. 3. Patients who were pregnant, menstruating or taking hormonal therapy. 4. Patients who has taken an antiemetic medication within 24 hours before surgery. 5. Patients who had a history of alcohol or drug abuse of the past 3months 6. Morbid obese patients.  The same standard general anesthesia technique was used in all groups. Patients were assessed for: 1. All episode of PONV. 2. The need for rescue antiemetic medication. 3. Undesirable side effects as dizziness headache constipation or diarrhea will be recorded. 4. Postoperative pain according to VAS (visual analogue scale). 5. Hemodynamics (heart rate and main arterial blood pressure): by routine monitoring as pulse oximetry, ECG and non-invasive blood pressure during postoperative period. 6. Cost effectiveness; by calculation of cost effectiveness and evaluation of granistron efficacy in different doses between patient groups. In our study, we showed that the efficacies of granisetron 20 µg/kg, granisetron40 µg/kg and granisetron 80 µg/kg for the prevention of PONV were all superior to that of granisetron 10 µg/kg (all p < 0.05). These findings suggest that granisetron20 µg/kg is the minimum effective dose for the treatment of PONV after laparoscopic surgery. The optimal dose of Granisetron to prevent PONV after various surgical procedures was found to be 40µ/kg. Higher doses have not been found to be more