A priming dose of intravenous ketamine-dexmedetomidine suppresses fentanyl-induced coughing: a double-blind, randomized, controlled study.

Objective: This study was designed to investigate whether a priming dose of ketamine-dexmedetomidine can effectively suppress fentanyl-induced coughing (FIC).

Methods: Altogether 400 patients of ASA I and II, aged 18-70 years, undergoing various elective surgical procedures, were randomly allocated into four groups of 100 patients each. Patients in the placebo group received volume-matched normal saline 0.15 mL/kg + normal saline 0.05 mL/kg. One group of patients was given ketamine 0.15 mg/kg + normal saline 0.05 ml/kg (KET), and another group dexmedetomidine 0.5 μg/kg + normal saline 0.05 ml/kg (DEX). Finally, one group of patients received ketamine 0.15 mg/kg + dexmedetomidine 0.5 μg/kg (KETODEX). After fentanyl administration, the onset time and severity of cough for 1 min were recorded. Cough severity was graded as mild (grade 1-2), moderate (grade 3-5), or severe (grade >5).

Result: The incidence of FIC was 53%, 34%, 20%, and 9% in the placebo, DEX, KET, and KETODEX groups, respectively. The incidence of cough was significantly lower in the KETODEX group. Likewise, the onset time of cough was significantly delayed in the KETODEX group. Only nine patients in the KETODEX group had either mild (6%) or moderate (3%) cough, with none suffering from severe cough.

Conclusion: A priming dose of KETODEX effectively suppressed the cough reflex induced by fentanyl and delayed the onset time of cough. Therefore, treatment with KETODEX may be a clinically useful method for preventing FIC.