Comparison of ondansetron & dexamethasone in prevention of postoperative nausea & vomiting in laparoscopic surgery

Objectives: Incidence of post-operative nausea and vomiting (PONV) is high in patients undergoing laparoscopic surgeries under general anaesthesia. Aim of this study is to compare dexamethasone and ondansetron in preventing PONV.Methods: In this randomized, open clinical trial, we studied 100 ASA Grades I, II and III patients between the ages of 20 and 60 years undergoing elective laparoscopic surgeries under general anaesthesia. Group I received 4 mg of ondansetron i.v. and group II received 8 mg of dexamethasone i.v. 5 minutes before the induction of anaesthesia. The incidences of PONV were recorded with in the first 24 hours after surgery at intervals of 0-2 hours, 2- 6 hours and 6-24 hours.Results and conclusion: Nausea in the first two hours of post-operative period was significantly more in Group D as compared with Group O. In the 2 6 hour period and 6 24 hours period nausea was present in both the Groups and was statistically insignificant. There was no statistically significant difference between both the groups in incidence of vomiting and PONV in postoperative period. Incidence of PONV is not related to increase BMI, phases of menstrual and inhalational anaesthetic agent used. We conclude that ondansetron given intravenously just before induction is safe and more effective than intravenous dexamethasone in early nausea and vomiting and dexamethasone reduces delayed post-operative nausea and vomiting in patients undergoing elective laparoscopic surgeries.

IJBR (2014) 05 (02) www.ssjournals.com after intubation. Maintenance of anaesthesia was with nitrous oxide (50%) and oxygen (50%) with halothane /isoflurane/sevoflurane and Inj. vecuronium 0.08 mg/kg i.v. was used to provide muscle relaxation during surgery using controlled ventilation through closed circuit. Patients were monitored during anaesthesia using continuous ECG, heart rate, blood pressure, EtCO2 and pulse oximetry. On completion of surgery, the residual paralysis was reversed with Inj. glycopyrrolate 0.008 mg/kg i.v. and Inj. neostigmine 0.05 mg/kg i.v. Extubation of trachea was done after adequate oral suctioning and criteria for extubation were fulfilled. Inj. diclofenac sodium 1.5 mg/kg i.v. was given for post-operative analgesia. Patients were transported to the recovery room and later to the ward after confirming an adequate level of consciousness and intact reflexes. The incidences of PONV were recorded with in the first 24 hours after surgery at intervals of 0-2 hours, 2-6 hours and 6-24 hours.    On comparing female patients in group D and group O ( Table 2) for PONV in relation to follicular, luteal and menstrual phase of menstrual cycle showed that the difference was statistically insignificant. On comparing patients in group D and group O ( Table 2) for PONV in relation to inhalational agents halothane, isoflurane and sevoflurane showed that the analysis was statistically insignificant.

Results
In www.ssjournals.com vomiting while 5 patients (10%) out of 50 in the 6-24 hours period experienced vomiting in Group O. This analysis was found to be statistically nonsignificant. In Group D, 30 patients (60%) out of 50 experienced PONV, while in Group O, 17 patients (34%) out of 50 experienced PONV in the first twenty four hours of post-operative period. This analysis was found to be statistically significant. The total number of patients suffering from PONV is 47 out of 100 patients.
In Group O, 17 patients (34%) out of 50 experienced PONV and only 3 patients (18%) required rescue-antiemetics while 14 patients (88%) who experienced PONV did not require rescue-antiemetics. This analysis was found to be statistically insignificant.

Discussion
Postoperative nausea and vomiting (PONV) is of multifactorial origin. Three most common causes for admission following day care surgery are pain, bleeding and intractable vomiting. This can delay discharge and result in unplanned overnight hospital admission. In fact, its contribution to patient dissatisfaction is such that over 70% of patients considered avoidance of PONV to be very important 4 . Anxiety increases the incidence of PONV. 5 In our study anxiolysis was provided with Inj. midazolam 0.05 mg/kg i.v. as premedication. Lack of control group (placebo) in our study is a drawback. However, conducting a surgery with a high incidence of PONV, without any prophylactic antiemetic was not acceptable. Laparoscopic surgeries were taken in the study as it is an independent predictor of PONV. 6 In our study the incidence of PONV is not related to increase BMI as also seen in study by Kranke et al 7 . There was no relationship between incidence of PONV and phases of menstrual cycle in our study and is supported by studies done by Panditrao et al 8 and Irwin et al 9 . There is no difference between the three inhalation anaesthetics currently used with regard to frequency or severity of postoperative nausea, vomiting, or both also seen byWallenborn. 10 Prolonged duration of surgery is an independent risk factor for PONV. 6 Nausea in the first two hours of post-operative period was significantly more in Group D as compared with Group O. In the 2 -6 hour period and 6 -24 hours period nausea was present in both the Groups and was statistically insignificant. Similar findings were seen in study done by Gautam B 11 .There was no statistically significant difference between both the groups in incidence of vomiting and PONV in postoperative period as also seen in studies by Thomas and Jones 12 Mehernoor et al 13 suggested that, administering a repeat dose of same antiemetic to patients who have already received a prophylactic dose, fails to control established PONV. So an antiemetic from a different 14 pharmacological, Metoclopramide 10mg was used as rescue antiemetic in our study.
Updated guidelines 14 for managing postoperative nausea and vomiting were announced at the 2006 Annual Meeting of the American Society of Anaesthesiologists in Chicago, Illinois, USA. Evaluating the current medical literature, they recommended the use of antiemetic, with an emphasis on the use of the 5HT3 receptor antagonists. The guidelines also suggest a potential benefit of combination prophylaxis. Overall the panel recommended prophylactic therapy with combination, three or more interventions, in patients at high risk for PONV group should be used as rescue antiemetic.

Conclusion
PONV is one of the most distressing side-effects of anaesthesia and surgery with a high incidence following general anaesthesia .The quest for more effective antiemetic drugs without the potential for sedative or extrapyramidal side-effects has led to the development of a relatively new class of drugs, 5-HT3 antagonists of which ondansetron is a prototype.
We conclude that ondansetron given intravenously just before induction is safe and more effective than intravenous dexamethasone in early nausea and vomiting and dexamethasone reduces delayed post-operative nausea and vomiting in patients undergoing elective laparoscopic surgeries under general anaesthesia. There was no relationship between incidence of PONV and phases of menstrual cycle and inhalational agents used.