Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Pediatric Anesthesia
Introduction: The 5-HT3 receptor antagonists ondansetron and granisetron have been shown to decrease post-op nausea and vomiting (PONV) in pediatric outpatient (OP) surgery [1,2], however they are expensive when used intravenously. Recently, preoperative oral ondansetron was shown to decrease PONV following tonsillectomy and at reduced cost . This study was designed to determine the doseresponse relationship and cost effectiveness of preoperative oral granisetron in reducing PONV after pediatric OP strabismus surgery.
Methods: A randomized, double blind, placebo controlled trial studied 59 ASA 1-2 children aged 1-12 years undergoing strabismus surgery. With IRB approval and parental consent, children were allocated to receive either placebo, low dose (20 mcg/kg) or high dose (40 mcg/kg) granisetron 20 mins prior to induction. All patients received 0.1 ml/kg of the study drug orally. Anesthesia consisted of halothane/N (2) O induction, insertion of a LMA and maintenance with isoflurane/N2 O. Glycopyrrolate 10 mcg/kg IV, ketorolac 0.5 mg/kg IV and rectal acetaminophen 20 mg/kg were administered intra-op, and all children received fluids as per existing protocols. At the end of surgery the LMA was removed with the patient deep and the stomach was suctioned. Perioperative data was collected, post-op pain was treated with morphine 0.05 mg/kg IV and > 1 episode of emesis with metoclopramide 0.15 mg/kg IV. A phone call 24 hrs later inquired about PONV after discharge and the use of analgesics and antiemetics. Statistical analysis used Chi-square, unpaired t test and ANOVA.
Results: The groups had similar demographic data, number of eyes or muscles operated on, length of anesthesia and surgery, fluid and analgesic requirements, and PACU stay. No patients were admitted due to prolonged post-op emesis. The incidence of PONV is shown below. (Table 1)
Discussion: Preoperative oral granisetron was effective in reducing the incidence of PONV following pediatric OP strabismus surgery. The granisetron syrup costs $15.58/mg and is slightly cheaper on a dose/kg basis than ondansetron ($2.18/mg). With a shelf-life of 2 weeks granisetron may make an economically attractive alternative in this high risk group of patients. A previous study  showed 40 mcg/kg IV (but not 10 mcg/kg IV) to be effective. In this study, an oral dose of 20 mcg/kg was as effective as 40 mcg/kg in decreasing both in-hospital emesis and emesis during the first 24 hours. This work suggests that 20 mcg/kg may be the optimal oral dose. Further studies are needed to compare selective 5-HT3 antagonists with other established antiemetics.
1. Anesthesiology 1996;85:1076-85
2. Anesthesiology 1995;82: 47-52
3. Anesth Analg 1996;82:558-62