Efficacy of risk score dependent antiemetic regimens in reduction of post operative nausea and vomiting

Postoperative nausea and vomiting (PONV) is a common complication after anaesthesia. Although self limiting and non fatal, it can cause significant morbidity and delay discharge. The intention of doing this study was, to evaluate the accuracy of three risk scores in predicting PONV and to evaluate the efficacy of different therapeutic regimens based on the risk score in the reduction of PONV. Materials and Methods: In this prospective, randomized, double blinded study, 180 patients between 18-60 years age group, belonging to ASA 1 and ASA 2 categories coming for elective surgeries under general anaesthesia of 1-4hrs duration irrespective of the type of surgery were scored preoperatively for postoperative nausea and vomiting using APFEL, KOIVURANTA, PALAZZO and EVANS scoring systems into low risk and high risk groups. Low risk group (i.e., Group O) consisting of 60 patients - inj. ondansetron 4mg was given intravenously 30 minutes before administration of reversal agent. High risk group was further categorized into Group M and Group D consisting of 60 patients each, based on the intervention to assess the efficacy of the drugs used in these two groups. Group M patient received inj.ondansetron 4mg+inj.metoclopramide 10mg intravenously (IV) 30 minutes before administration of reversal agent. Group D patient received inj. dexamethasone 4mg IV at induction and inj.ondansetron 4mg IV 30 minutes before administration of reversal agent. After the procedure, patients were observed for any retching, nausea or vomiting in postanaesthesia care unit and up to 24 hours. Rescue treatment from a drug of different pharmacological group was administered if required. Results: Area under the curve (AUC) and the corresponding 95% confidence intervals for the scores drawn from Receiver operator characteristic (ROC) curves were: Apfel: 0.6154 (0.50470-0.72618); Koivuranta: 0.6154 (0.50470-0.72618); Palazzo & Evans: 0.6443 (0.54096-0.74764). And, a complete response of 71.67% was observed in Group O, 76.67% in Group M and 90% in Group D. Thus we concluded that, all the three scores had moderate accuracy in predicting the risk of PONV and ondansetron-dexamethasone combination was found to be superior to ondansetron- metoclopramide combination in high risk patients.