A randomised control trial of ondansetron and metoclopramide in the prevention of post operative nausea and vomiting in thyroidectomy patients

Backgrounds: Nausea, retching and vomiting are among the most common post operative complaints next to pain for patients undergoing all surgical procedures requiring sedation and anaesthesia-general, regional or local anaesthesia. The incidence of post operative nausea and vomiting has been reported to be 1 in 1000,[1,2]. John Snow in 1848 has given extensive descriptions on nausea and vomiting[3] .He observed that vomiting was more likely to occur if the patient had eaten recently. Persistent nausea and vomiting may result in dehydration, electrolyte imbalance and delayed discharge after outpatient surgeries[4] . Objectives: Primary objective is to find out the effectiveness of Ondansetron and Metoclopramide in the prevention of post operative nausea and vomiting in thyroidectomy patients. Secondary objectives are 1) to compare the incidence of nausea and vomiting in patients administered with ondansetron and the control.2) To compare the incidence of nausea and vomiting in patients administered with metoclopramide and the control.3) To compare the effectiveness of ondansetron with metoclopramide in the prevention of PONV.4)To find whether there is any co relation between the type of drug and clinical recovery score Methodology: A randomized control trial involving 60 female patients of ASA I in the age group 21-45 years undergoing elective thyroidectomy under general anaesthesia. The study was conducted in the department of Anaesthesiology and General surgery in Government Medical college,Trivandrum.The patients were randomly allocated into 3 groups of 20, group I (control group),treated with placebo2)Study group! –treated with ondansetron 4 mg IV 3) Study groupII treated with metoclopramide 10 mg IV..All patients were pre medicated with oral diazepam 10 mg on night before surgery and 10 mg at 6 AM on the day of surgery.For all patients an IV line was established on left forearm with an 18G cannula and 5% dextrose in water was started.Then, control group received 2 ml of normal saline IV over 1-2 minutes 5 minutes prior to induction of anaesthesia.Study groupI received 4mg of ondansetron IV over 1-2 minutes 5 minutes prior to induction of anaesthesia. Study groupII received 10mg of metoclopramide IV over 1-2 minutes 5 minutes prior to induction of anaesthesia..General anaesthesia was induced with inj. thiopentone sodium 5mg/kgiv.,Inj.Morphine 0.1 mg/kg IV and Succamethonium 1.5 mg/kg IV.Patients were intubated and anaesthesia was maintained with nitrous oxide 60%,Oxygen 40% , halothane 0.5% and Inj. Vecuronium 0.08 mg iv.At the end of surgery, neuromuscular blockade was reversed and patients were shifted to post operative recovery room, where patients were assessed at 0,30,60 and 120minutes for nausea and vomiting, clinical recovery score, blood pressure, pulse rate and at the end of 24 hours for nausea grade, emetic episodes, side effects like head ache, dyskinesis, pyrexia, hypertension etc. and also about any rescue antiemetics taken( eg; Inj.Promethazine 25mg IV) Results : The overall incidence of nausea is 45%.It was only 15% in the ondansetron group and 55 to 65% in the other two groups It is evident that the reduction in the incidence of nausea in the. ondansetron group is definitely due to the effect of the drug and metoclopramide has little antiemetic effect post operatively. The overall incidence of vomiting was 60% post operatively within 24 hours. In ondansetron group 25% of patients had vomiting, 75% had vomiting in metoclopramide group and in control group 80% had vomiting. Frequency of vomiting at 1 hour and 2 hour is almost same with both Ondansetron and metoclopramide groups. But after 2 hours metoclopramide was found to have no effect on frequency of vomiting. Better clinical recovery score was achieved with ondansetron compared to metoclopramide at the end of 24 hours. No significant side effects were noted in all 3 groups. Conclusion: In conclusion a direct comparison of ondansetron 4 mg IV with metoclopramide 10 mg IV showed Ondansetron to be far more superior for the prophylaxis against PONV. Devoid of distressing side effects, ondansetron is a promising agent against PONV.