Intubating conditions and blockade after mivacurium, rocuronium and their combination in young and elderly adults

Purpose: Mivacurium-rocuronium combinations have been demonstrated to be mo re potent than either drug given alone. Combinations were compared with miv acurium and rocuronium, with respect to onset, intubating conditions, and d uration of action in young and elderly adults. Methods: Fentanyl-propofol-N2O-isoflurane anesthesia was given to ASA I and II adults aged 18-65 yr (45 patients) and over 66 yr (45 patients), In thi s blinded randomized study, we compared accelerographic adductor pollicis r esponse and visual assessment of response to facial nerve stimulation after 0.25 mg.kg(-1) mivacurium, 0.6 mg.kg(-1) rocuronium, and a combination of 0.08 mg.kg(-1) mivacurium plus 0.2 mg.kg(-1) rocuronium. Intubating conditi ons at 2.5 min were rated as excellent, good, fair or poor. Results: Onset times were similar for all drugs regimens and for both age g roups (204-276 sec at the thumb; 142-196 sec at the eye) (P < 0.05 between muscles). Intubating conditions were similar in all groups, and rated good or excellent, except in two subjects, In young patients duration to 25% rec overy was longer (P < 0.05) for rocuronium (mean +/- SD) (39 +/- 11 min) th an for either mivacurium (23 +/- 6 min), or the combination (27 +/- 7 min). Duration was prolonged in the elderly for rocuronium (54 +/- 17 min), and the combination ( 35 +/- 11 min), but not for mivacurium (24 +/- 6 min), Conclusions: Mivacurium-rocuronium combinations yield onset times and intub ating conditions similar to either parent agent with only two thirds as muc h total drug. Duration for such a mixture is similar to that of mivacurium in young adults and slightly prolonged in the elderly.