RESUMO
Preliminary disposition studies of the investigational, long-acting muscle relaxant doxacurium chloride (Nuromax) have demonstrated dual elimination by renal and hepatobiliary pathways, as well as slow hydrolysis by plasma cholinesterase. The present study compares the kinetics and dynamics of doxacurium in eight ASA physical status I or II elderly patients (67-72 yr of age) and eight ASA I or II young patients (22-49 yr of age). After institutionally approved written informed consent, kinetic and dynamic measurements were made after a 25-micrograms/kg bolus injection of doxacurium during 1.25 MAC nitrous oxide/oxygen/isoflurane anesthesia. Maximum twitch depression was similar in older patients (96.4% +/- 1.3%) to that in the young patients (96.6% +/- 1.8%). The time to achieve this level of block was significantly longer in the elderly than in the young (11.2 +/- 1.1 min versus 7.7 +/- 1.0 min, respectively). Recovery times to twitch heights of 5% and 25% of control tended to be prolonged and were more variable in the elderly (82.6 +/- 17.2 and 97.1 +/- 20.1 min, respectively) than in the young (54.8 +/- 9 and 67.5 +/- 8.2 min, respectively). Elimination half-life (96 +/- 20 min) and clearance (2.47 +/- 0.69 mL.kg-1.min-1) in the elderly patients were not statistically different from values found in the younger group. Volume of distribution at steady state in the elderly (220 +/- 80.2 mL/kg) was significantly larger than in the young (150 +/- 40.0 mL/kg).(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Envelhecimento/fisiologia , Anestesia por Inalação , Isoflurano , Isoquinolinas/farmacologia , Fármacos Neuromusculares não Despolarizantes/farmacologia , Adulto , Idoso , Hemodinâmica/efeitos dos fármacos , Humanos , Isoquinolinas/farmacocinética , Pessoa de Meia-Idade , Junção Neuromuscular/efeitos dos fármacos , Fármacos Neuromusculares não Despolarizantes/farmacocinéticaRESUMO
We describe the anaesthetic management of a patient with a rare form of muscular dystrophy (Facioscapulohumeral or Landouzy-Dejerine type). Anaesthesia and controlled ventilation using alfentanil-nitrous oxide and atracurium was satisfactory. In this patient, sensitivity to atracurium was found to be similar to that of the normal population, but more rapid recovery was observed.
