Single Prophylactic Dose Of Dexamethasone Antiemetic Versus Ondansteron In Patients Undergoing Middle Ear Surgery: A Comparative Clinical And Experimental Animal Study

This prospective, randomized, double-blinded, placebo-controlled study in which 150 ASA I-II patients scheduled for middle ear surgery were randomized into three equal groups. The dexamethasone group (group D) received a single dose of dexamethasone 10 mg IV at induction of anesthesia, ondansetron group (group O) received 4 mg IV ondansetron and the control group (group C) received 5 ml saline IV as placebo by the same technique. The study demonstrated that the incidence of early postoperative nausea, retching and vomiting (PONV) was significantly greater in the placebo group than the dexamethasone group (P<0.001) and the ondansetron group (P<0.001), indeed the incidence was comparable in the dexamethasone and ondansetron groups (P> 0.05). More over, the severity of late PONV (6-24h) was markedly less in the dexamethasone group than the ondansetron group (P< 0.05) and still the incidence of late PONV was markedly less in both dexamethasone and ondansetron groups than the control group (P< 0.001). The study also reported that postoperative analgesic requirement was notably lower in the dexamethasone group than the ondansetron and control groups. An experimental animal study was also done to assess the extrapyramidal reaction associated with the use of both dexamethasone and ondansetron. Increasing doses of both drugs were given IV to the rats, up to 5 times the therapeutic dose of each drug. The rats then stimulated for 24h after injection by light, sound and 6 volt electric current in the Rat Conditioning Chamber. No one rat developed akathisa or acute dystonic reaction. In conclusion, dexamethasone and ondansetron were quite effective and have limited side-effects profile when given as single prophylactic antiemetic doses in patients undergoing middle ear surgery. The advantages of dexamethasone over ondansetron were its prolonged antiemetic effect, its analgesic effect and the lower cost. Introduction Postoperative nausea, retching and vomiting (PONV) are among the most common complications after anesthesia and surgery, with a relatively high incidence after middle ear surgery (tympanoplasty or mastoidectomy). (1-2) PONV may lead to serious medical complications such as aspiration pneumonia (3) and dehydration (4) . It may delay discharge from the hospital with obvious economic (5) consequence, and at the very least is distressing to the patient (6) . The concept of using steroids for the prevention of PONV is not a new one (7-10) . Even though the concept is not 50 Refree : Prof ; Dr. Ibrahin Abd ElGany