Comparison of High Dose Ondansetron versus Low Dose Ondansetron for Prevention from Postansthesia Shivering

Background: Postanesthesia shivering (PAS) is a very common anesthesia-related complication the not only is a discomfortable phenomenon for that patients, but can cause undesirable events and affect the patient’s prognosis negatively. This study compares the high dose ondansetron versus low dose of this agent for PAS control. Methods: In this clinical trial 101 patients under general anesthesia for elective surgeries in three groups of premedication with high dose ondansetron (8mg) (n=33), low dose ondansetron (4mg) (n=34) and placebo (normal saline) (n=34) were evaluated. The agents were injected immediately before anesthesia induction, and hemodynamic data, nausea and vomiting incidence and shivering severity were compared. Results: Mean arterial pressure and pulse rate significantly decreased within the time (P-value<0.05), while oxygen saturation, peripheral and central body temperature did not have statistically significant alterations (P-value>0.05). The duration of recovery room stays and use of meperidine for shivering control were not different in the three groups (P-value>0.05), while incidence of nausea and vomiting and shivering intensity in placebo treated group was worse than ondansetron treated groups regardless of the dose (P-value<0.05). Comparison of two ondansetron treated groups represented insignificant difference considering nausea and vomiting and shivering intensity (P-value>0.05). Conclusion: Ondansetron use regardless of the dose was superior to placebo in terms of PAS intensity and nausea and vomiting prevention. Low dose of ondansetron (4mg) was superior to high dose (8 mg) considering the hemodynamic stability, while the two doses were similar in terms of PAS intensity, nausea and vomiting occurrence, duration of recovery room stay and meperidine requirement for shivering control.