Butorphanol premedication to facilitate invasive monitoring in cardiac surgery patients before induction of anaesthesia

Cannulations (peripheral vein, radial artery and jugular vein) performed for invasive monitoring before induction of anaesthesia in cardiac surgery patients may be associated with stress and anxiety. The efficacy and safety of butorphanol premedication was assessed in setting up of invasive monitoring. The study was a prospective, randomized, double blind, placebo controlled one with 70 patients undergoing elective cardiac surgery. In group-1 patients (n = 35) (placebo) intramuscular saline was administered 1-2 hours before the surgery in equivalent volume to butorphanol. In group-2 (n = 35) butorphanol (1, 1.5 and 2 mg for three body weight groups < 40 kg, 41-60 kg and> 60 kg, respectively) was administered 1-2 hours before surgery. Observer blinded for medication recorded the sedation score, pupil size and pain after each cannulation using visual analogue score (VAS). Student's 't' test and Chi-square test for proportions, Mann-Whitney test for non-parametric data was carried out. The median pain score of cannulation in group-2 (butorphanol) in the hand (10 mm) and neck (20 mm) were significantly (P < 0.05) lower than group-1 (placebo) patients (hand = 30 mm and neck = 40 mm). Pain during neck cannulation was significantly (P < 0.05) reduced (VAS < 30 mm) in patients with the pupil size of < 2.5 mm. Since the pain during neck cannulation was more than pain during hand cannulations in both the groups, we conclude that the intensity of pain depends also upon the site of cannulation. Besides the analgesic effect of butorphanol, its sedative effect helped to effectively decrease the pain during neck cannulation in conscious patients.