Antagonism of neuromuscular blockade but not muscle relaxation affects depth of anaesthesia.
BACKGROUND
Conflicting effects of neuromuscular blocking drugs and anticholinesterases on depth of anaesthesia have been reported. Therefore we evaluated the effect of atracurium and neostigmine on bispectral index (BIS) and middle-latency auditory evoked potentials (AAI).


METHODS
We studied 40 patients (ASA I-II) aged 18-69 yr. General anaesthesia consisted of propofol and remifentanil by target-controlled infusion and neuromuscular function was monitored by electromyography. When BIS reached stable values, patients were randomly assigned to one of two groups. Group 1 received atracurium 0.4 mg kg(-1) and, 5 min later, the same volume of NaCl 0.9%; group 2 received saline first and then atracurium. When the first twitch of a train of four reached 10% of control intensity, patients were again randomized: one group (N) received neostigmine 0.04 mg kg(-1) and glycopyrrolate 0.01 mg kg(-1), and the control group (G) received only glycopyrrolate.


RESULTS
Injection of atracurium or NaCl 0.9% had no effect on BIS or AAI. After neostigmine-glycopyrrolate, BIS and AAI increased significantly (mean maximal change of BIS 7.1 [SD 7.5], P<0.001; mean maximal change of AAI 9.7 [10.5], P<0.001). When glycopyrrolate was injected alone BIS and AAI also increased (mean maximal change of BIS 2.2 [3.4], P=0.008; mean maximal change of AAI 3.5 [5.7], P=0.012), but this increase was significantly less than in group N (P=0.012 for BIS; P=0.027 for AAI).


CONCLUSIONS
These data suggest that neostigmine alters the state of propofol-remifentanil anaesthesia and may enhance recovery.
Vasella
F C
FC
Department of Anaesthesiology, University Hospital, CHUV BH-10, 1011 Lausanne, Switzerland.
Frascarolo
P
P
Spahn
D R
DR
Magnusson
L
L
D000328:Adult; D000368:Aged; D019162:Anesthetics, Combined / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D001279:Atracurium / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D004311:Double-Blind Method; D004347:Drug Interactions; D004569:Electroencephalography / Q000187:drug effects; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D009126:Muscle Relaxation / Q000187:drug effects*; D009388:Neostigmine / Q000494:pharmacology; D019148:Neuromuscular Blockade; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D015742:Propofol / Q000494:pharmacology; D011446:Prospective Studies; D000077208:Remifentanil
D019162:Anesthetics, Combined; D018686:Anesthetics, Intravenous; D002800:Cholinesterase Inhibitors; D003473:Neuromuscular Nondepolarizing Agents; D010880:Piperidines; D001279:Atracurium; D009388:Neostigmine; D000077208:Remifentanil; D015742:Propofol