Fentanyl is commonly used as a preinduction adjunct to general anaesthesia. Incidence of fentanyl induced cough varies between 18-65%. Aims of the study are to evaluate the occurrence rate and severity of fentanyl induced cough and comparison of effectiveness of ketamine (0.5 mg/kg), priming dose of Fentanyl (0.5 ?g/kg) one min before bolus of Fentanyl and diluted Fentanyl (10 cc with saline) to suppress fentanyl induced cough. 400 patients posted for elective surgeries under general anaesthesia were randomly allocated into 4 groups of 100 patients. During induction, Group S received saline and Group PK received Inj. Ketamine Hydrochloride (0.5 mg/kg) one minute before Inj. Fentanyl 2 ?g/kg. Group PF received Inj. Fentanyl Citrate (0.5 ?g/kg) one minute before Inj. Fentanyl 1.5 ?g/kg. Group DF received Inj. Fentanyl 2 ?g/kg diluted in saline upto 10 cc over 30 sec. Observation was done for occurrence and severity of cough for three minutes and heart rate, systolic and diastolic blood pressure at 1 min before and 5 min after giving bolus of fentanyl. Incidence of fentanyl induced cough is significantly lower in Group DF (2%) as compared to others (45% in Group S, 10% in Group PK, 14% in Group PF). (p< 0.0001) Severity grade was mild (1-2 episode) in Group DF as compared to others. (p 0.0001) Dilution of fentanyl (10 ?g/ml) with normal saline and prolonged injection time is the simple and cost effective method to prevent fentanyl induced cough
