British Journal of Anaesthesia, Vol 82, Issue 1 61-65, Copyright © 1999 by The Board of Management and Trustees of the British Journal of Anaesthesia
T. Fuchs-Buder, T. Ziegenfuss, K. Lysakowski and E. Tassonyi
We have investigated the dose-effect relationship of neostigmine in
antagonizing vecuronium-induced neuromuscular block with and without
magnesium sulphate (MgSO4) pretreatment. Neuromuscular block was assessed
by electromyography with train-of-four (TOF) stimulation. First, we
determined neostigmine-induced recovery in patients pretreated with MgSO4
(group A) or saline (group B) (n = 12 each). The height of T1, 5 min after
neostigmine, was 43 (7)% in group A and 65 (6)% in group B (P < 0.01).
Respective values after 10 min were 59 (7)% and 83 (5)% (P < 0.01). TOF
ratio, 5 min after neostigmine, was 29 (6)% in group A and 29 (5)% in group
B. Respective values after 10 min were 38 (11)% and 51 (7)% (P < 0.01).
To gain insight into the mechanisms leading to delayed recovery after
MgSO4, we calculated assisted recovery, defined as neostigmine-induced
recovery minus mean spontaneous recovery. Spontaneous recovery was assessed
in another 24 patients. Patients in group C received MgSO4/vecuronium and
patients in group D vecuronium only (n = 12 each). Five minutes after
neostigmine, assisted recovery was 22 (7)% in the MgSO4 pretreated patients
and 28 (6)% in controls (P < 0.05). Ten minutes after neostigmine,
values were 24 (7)% and 22 (6)%. Maximum assisted recovery was not
influenced by MgSO4 pretreatment (27 (6)% in group A and 32 (6)% in group
B) and time to maximum effect was comparable between groups: 6 (4-10) min
and 7 (5- 8) min, respectively. We conclude that neostigmine-induced
recovery was attenuated in patients treated with MgSO4. This was mainly a
result of slower spontaneous recovery and not decreased response to
neostigmine.
CLINICAL INVESTIGATIONS
Antagonism of vecuronium-induced neuromuscular block in patients pretreated with magnesium sulphate: dose-effect relationship of neostigmine
Department of Anaesthesia and Critical Care, University of the Saarland, D-66421 Homburg/Saar, Germany; Division of Anaesthesia, Geneva University Hospital, CH-1211 Geneva, Switzerland
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