Dexamethasone and Ondansetron Versus Placebo for Postoperative Nausea and Vomiting

Obese patients having bariatric surgery have frequently postoperative nausea and vomiting (PONV). We want to test if it is indicated to associate dexamethasone and ondansetron in obese patients having bariatric surgery under total intra-venous closed-loop anesthesia.

Two groups to be studied: one will receive 4 mg dexamethasone at the end of the anesthetic induction and 4 mg ondansetron at the end of the surgical procedure, one will receive normal saline.

One hundred twenty consecutive patients meeting the inclusion and exclusion criteria and who give written informed consent to participate in the study will be randomly assigned to one of two experimental groups using a 1:1 ratio.

Patients will be continuously monitored in the post anesthesia care unit (PACU) and the medical floor for a total of 24 hours post operatively. Episodes of nausea, vomiting and administration of rescue therapy for either nausea or vomiting will be recorded and time stamped. In addition, severity of nausea will be evaluated by the patient using a standard verbal response scale (VRS) ranging from 0-10, 0 being no nausea and 10 being severe nausea. Rescue therapy for PONV episodes will consist of 4 mg ondansetron followed by 0.625 mg droperidol if necessary.

Inclusion criteria

• Adult patients aged 18-75 years
• Scheduled for bariatric surgery under total intra-venous closed-loop anesthesia
• Apfel score equal or greater than 2
• Consenting to participate in the study

Exclusion criteria

• Pregnant, breast feeding women
• Allergy
• Contraindication to dexamethasone
• Contraindication to ondansetron
• Contraindication to propofol, remifentanil, morphine, ketoprofen
• Limit to the use of bispectral index