Eighty patients, ASA physical status II-IV, scheduled for noncardiac surgery, were randomly assigned in a double-blind, placebo-controlled manner to receive a preintubation dose of either placebo, 200 mg lidocaine, 200 micrograms fentanyl, or 150 mg esmolol. Induction of anesthesia was accomplished with 4-6 mg/kg thiopental IV followed immediately by the study drug; 1-1.5 mg/kg succinylcholine was given at minute 1. Laryngoscopy and intubation were performed at minute 2 with anesthesia thereafter maintained with 1 MAC (+/- 10%) isoflurane in 60% nitrous oxide in oxygen at a 5 L/min flow for 10 min. Heart rate was recorded every 15 s and blood pressure every minute from induction until 10 min after intubation. Maximum percent increases in heart rate (mean +/- SE) during and after intubation were similar in the placebo (44% +/- 6%), lidocaine (51% +/- 10%), and fentanyl (37% +/- 5%) groups, but lower in the esmolol (18% +/- 5%) group (P less than 0.05). Maximum systolic blood pressure percent increases were lower in the lidocaine (20% +/- 6%), fentanyl (12% +/- 3%), and esmolol (19% +/- 4%) groups than in the placebo (36% +/- 5%) group (P less than 0.05), but not different from each other (P greater than 0.05). Only esmolol provided consistent and reliable protection against increases in both heart rate and systolic blood pressure accompanying laryngoscopy and intubation.

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Summary Key wordsHeart; tachycardia. Sympathetic nervous system; 8-adrenergic antagonists, esmolol.Tachycardia and hypertension are undesirable in patients with ischaemic heart disease, but tachycardia increases myocardial oxygen consumption more than hypertension, and results in a greater incidence of myocardial ischaemia.' Heart rates (HR) greater than 100 beats/minute have been associated with increased incidences of ischaemia and myocardial infarction.2 Intra-operative tachycardia may be caused by severe painful surgical stimulation, unrecognised light anaesthesia, or numerous other causes. Increased anaesthetic depth and adrenergic blockers are frequently chosen to control heart rate. Volatile agents can cause cardiovascular depre~sion,~ while opioids prolong recovery time and cause postoperative respiratory depre~sion.~ Most adrenergic blockers outlast the transient stimulus and may cause prolonged hypotension and brady~ardia.~ Esmolol, an ultrashort-acting cardioselective beta-blocker has an elimination half-life of 9 minutes and plasma concentrations are undetectable after 15 minutes.6 The objective of this study was to examine the effectiveness of a single bolus dose of esmolol(50 mg or 100 mg compared to placebo) in treating surgically-induced increases of heart rate regardless of stimulus. MethodsThe study design was double-blind, randomised, parallel and placebo-controlled, and was approved by the institutional Human Studies Subcommittee. Eligible patients were those in ASA classes 2 to 4 scheduled to undergo general or orthopaedic surgical procedures and who had given written informed consent. Patients with atrioventricular conduction block greater than first degree, atrial fibrillation or flutter, asthma, or severe cardiac, renal, or hepatic disease were not studied, nor were patients in ASA class 1. Premedication consisted of midazolam 0.03 mg/kg and glycopyrronium 0.2 mg intramuscularly 30-90 minutes before induction. Standard monitoring was performed in the operating room (electrocardiogram, Accutor noninvasive blood pressure monitor, SARA mass spectrometer and Nellcorr pulse oximeter). Anaesthetic technique was identical in all patients, and consisted of induction with thiopentone 4-6 mg/kg, suxamethonium 1-1.5 mg/kg, tracheal intubation, and maintenance with isoflurane 0.6% +0.06% (end-tidal) and 60% nitrous oxide in oxygen at a flow rate of 5 litres/minute (1 MAC total) for 10 minutes. By definition, we expected 50% of patients to respond by movement in all three groups. The lungs were ventilated to achieve an end-tidal carbon dioxide tension of 4 kPa. Inhalation anaesthesia was continued for a further 10 minutes; if, after this time, systolic blood pressure (SBP) was at least 110 mmHg, patients entered the study if, in response to surgical stimulation, the heart rate (HR) increased either to: greater than 95 beats/minute; or greater than 20% of pre-induction values. Patients did not enter the study if SBP was < 110 mmHg and anaesthesia was lightened. Two qualifying (baseline) HR and SBP valu...

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