Effect of bolus dose of remifentanil on haemodynamic response to tracheal intubation

A randomized placebo-controlled double-blinded study was conducted in 40 AS A 1 and 2 patients to determine the dose response of remifentanil in attenu ating the haemodynamic response to tracheal intubation. Patients were alloc ated to one of four groups: placebo, remifentanil 1 mu g.kg(-1), remifentan il 2 mu g.kg(-1) and remifentanil 4 mu g.kg(-1). A propofol target-controll ed infusion was started at 4 mu g.ml(-1) and incrementally titrated to loss of verbal contact, Muscle relaxation was provided by cisatracurium. The st udy drug was given three minutes later over 30 seconds, and 90 seconds late r the patient's trachea Il,as intubated under direct laryngoscopy. Baseline noninvasive blood pressure an heart rate recordings were made prior to sta rting target-controlled infusion, then at one-minute intervals after loss o f verbal contact for the duration of the study. Demographic data and target -controlled infusion rate at intubation was similar for the groups. Followi ng intubation, heart rate increased by 15% in the placebo group, 10% iii I mu g.kg(-1) group, with no changes ill 2 mu g.kg(-1) and 4 mu g.kg(-1) grou ps. Systolic blood pressure following intubation ina eased by 30% in the pl acebo group, 10% in the I mu g.kg(-1) group and remained unchanged in the 2 mu g.kg(-1) and 4 mu g.kg(-1) groups. Remifentanil I mu g.kg(-1) attenuate d the rise in heart rate and systolic blood pressure. Remifentanil 2 mu g.k g(-1) blocked the haemodynamic response completely: no further benefit was shown from increasing the dose to 4 mu g.kg(-1).