Efficacy of Low-Dose Ondansetron Combined with Dexamethasone for the Prevention of Postoperative Nausea and Vomiting Following Total Knee Arthroplasty

Efficacy of Low-Dose Ondansetron Combined with Dexamethasone for the Prevention of Postoperative Nausea and Vomiting Following Total Knee Arthroplasty

This randomized, double-blind, parallel-group phase II/III clinical trial will enroll 110 patients assigned 110 patients assigned to one of two groupsansetron plus dexamethasone or placebo plus dexamethasone, administered by injection before induction of anesthesia. No separate control group will be included. Randomization will be performed using permuted blocks of four.

In this randomized, double-blind trial on total knee arthroplasty patients at Imam Reza Hospital (Tabriz), participants will receive IV dexamethasone (0.2 mg/kg) combined with either ondansetron (0.05 mg/kg) or saline placebo 10 minutes pre-induction; patients and outcome assessors will remain blinded using identical, code-labeled syringes prepared independently.

Inclusion Criteria: Candidates for total knee arthroplasty under general anesthesia Patients with ASA Physical Status I and II Exclusion Criteria: Patients with known hypersensitivity to the study medications Patients with a history of postoperative nausea and vomiting

In this study, conducted at Imam Reza Hospital in Tabriz, patients undergoing total knee arthroplasty will be assigned to two groups: Group A will receive low-dose ondansetron combined with dexamethasone, and Group B will receive dexamethasone plus a placebo, prior to the induction of anesthesia. The administration of these medications will be performed by the attending anesthesiologist.

Postoperative nausea and vomiting

In this study, with a sample size of 110 , participants will be assigned to three groups using permuted block randomization. A block size of four will be employed, utilizing all possible combinations, including: Block 1 (BBAA), Block 2 (AABB), Block 3 (ABAB), Block 4 (BABA), Block 5 (ABBA), and Block 6 (BAAB). To accommodate 110 participants, 28 blocks will be generated using Random Allocation Software, with blocks randomly selected from numbers 1 to 6. For instance, if block 6 and block 2 are selected sequentially, the allocation sequence will be BAABAABB, assigning individuals to Intervention Group (A)and the Control Group (B). To ensure allocation concealment, the randomization list will be prepared and numbered by an independent researcher who is not involved in patient recruitment or assessment. The assignments will be placed in sequentially numbered, opaque, sealed envelopes (SNOSE). The study investigator will open the envelopes in numerical order only after a patient has been formally enrolled and their code has been recorded, ensuring that the allocation sequence remains unpredictable.

In this study, to ensure proper patient blinding, the medications for groups A and B will be prepared in identical appearance, color, packaging, and administration method, making them indistinguishable to participants. Each medication will be labeled with a unique code (A or B), known only to an independent researcher who is not involved in patient recruitment or evaluation. The envelopes containing the coded medication will be provided to the study investigator in sequential order, without any indication of treatment type. Consequently, both patients and the investigator will remain unaware of group allocation, thus maintaining a practical and effective double‑blind design throughout the trial.