[Atracurium in the elderly subject].

The effects of age on the pharmacodynamics of atracurium have been studied in twenty-four consenting adult patients undergoing elective surgery. They were divided in three groups according to their age (mean +/- SEM): group 1 (n = 8; 26 +/- 3 yr), group 2 (n = 8; 53 +/- 2 yr) and group 3 (n = 8; 76 +/- 2 yr). Anaesthesia was induced with methohexitone (1 mg . kg-1) and fentanyl (5 micrograms . kg-1), and maintained with 66% N2O plus fentanyl on demand. Ventilation was controlled and adjusted to produce normocapnia. The isometric contraction of the adductor pollicis muscle in response to supramaximal cubital nerve stimulation delivered at 0.1 Hz was measured with a force displacement transducer. A loading dose of atracurium (0.3 mg . kg-1) was given before tracheal intubation. Thereafter, twitch height (TH) was maintained at 10% of its baseline reading by adjusting the flow of a Harvard syringe containing 0.5 mg . ml-1 of atracurium in saline. The amount of atracurium required to maintain a stable twitch height, calculated for a 60 min period, was 14.7 +/- 1 mg . m-2 . h-1 for group 1, 13.6 +/- 1.5 mg . m-2 . BSA-1 for group 2 and 15 +/- 2.1 mg . m-2 . BSA-1 for group 3. At the end of the infusion period, the TH25-75 recovery rates were not statistically different in the three groups: 15.4 +/- 1.9 min for group 1, 14.8 +/- 1.1 min for group 2 and 14.5 +/- 1.6 min for group 3.(ABSTRACT TRUNCATED AT 250 WORDS)