The Effect of Ketamine and Dexamethasone on Frequency and Intensity of Fentanyl-Induced Cough

Intravenous (IV) administration of fentanyl during induction of general anesthesia often elicits cough, with frequency of 18% to 80%. Therefore, in this study, we aimed to compare the effects of ketamine and dexamethasone on decreasing cough in patients undergoing general anesthesia with fentanyl.
During a double-blind randomized clinical trial study, 99 patients aged 18-64 years with class I and II based on the scale of American Society of Anesthesiologists (ASA) who were undergoing general anesthesia with fentanyl were investigated. Patients were randomly divided equally into 3 groups receiving ketamine (0.5 mg/kg), dexamethasone (0.1 mg/kg), and placebo (5 ml normal saline). All drugs were administered 1 minute before administration of 2.5 µg/kg fentanyl. Vital signs, and frequency and intensity of cough were measured and recorded. Statistical analysis was performed using one-way ANOVA and Kruskal-Wallis tests.
Findings: The frequency of cough was significantly lower in the ketamine group (81.8%) compared with dexamethasone (90.9%) and placebo (93.1%) groups (P = 0.03). The intensity of cough was significantly lower in the ketamine group (mild: 18.2%; moderate: 78.8%; severe: 3.0%) compared with placebo group (mild: 9.1%, moderate: 72.7%; severe: 18.2%) (P = 0.04). Furthermore, there were significant differences between the three groups in variations of systolic blood pressure, diastolic blood pressure, and heart rate (P Administration of low-dose ketamine can effectively reduce frequency and intensity of fentanyl-induced cough during anesthesia in patients undergoing general anesthesia.