Pretreatment with sedative-hypnotics, but not with nondepolarizing muscle relaxants, attenuates alfentanil-induced muscle rigidity.
OBJECTIVE
To evaluate and compare the efficacy of various pretreatment agents to attenuate or prevent opioid-induced muscle rigidity using a well-established, previously described clinical protocol.


METHODS
Prospective, controlled, single-blind, partially randomized study.


METHODS
Large medical center.


METHODS
ASA physical status I-III patients undergoing elective surgical procedures of at least 3 hours' duration.


METHODS
The effect of pretreatment with nondepolarizing muscle relaxants (atracurium 40 micrograms/kg or metocurine 50 micrograms/kg), benzodiazepine agonists (diazepam 5 mg or midazolam 2.5 mg), or thiopental sodium 1 mg/kg on the increased muscle tone produced by alfentanil 175 micrograms/kg was compared with a control group (given no pretreatment).


RESULTS
Rigidity was assessed quantitatively by measuring the electromyographic activity of five muscle groups (biceps, intercostals, abdominals, quadriceps, and gastrocnemius). Rigidity also was rated qualitatively by attempts to initiate and maintain mask ventilation, attempts to flex an extremity, and the occurrence of myoclonic movements. Pretreatment with the two nondepolarizing muscle relaxants had no effect on the severe muscle rigidity produced by high-dose alfentanil. Whereas thiopental was only mildly effective, the benzodiazepines midazolam and diazepam significantly attenuated alfentanil rigidity (p < 0.05).


CONCLUSIONS
This study suggests that benzodiazepine pretreatment is frequently, but not always, effective in preventing opioid-induced muscle rigidity.
Sanford
T J
TJ
Department of Anesthesiology, University of California, San Diego, School of Medicine.
Weinger
M B
MB
Smith
N T
NT
Benthuysen
J L
JL
Head
N
N
Silver
H
H
Blasco
T A
TA
D000009:Abdominal Muscles / Q000187:drug effects; D015760:Alfentanil / Q000009:adverse effects* / Q000037:antagonists & inhibitors; D001279:Atracurium / Q000008:administration & dosage / Q000494:pharmacology; D003975:Diazepam / Q000008:administration & dosage / Q000494:pharmacology; D017558:Elective Surgical Procedures; D004576:Electromyography; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology*; D007366:Intercostal Muscles / Q000187:drug effects; D008874:Midazolam / Q000008:administration & dosage / Q000494:pharmacology; D008875:Middle Aged; D009127:Muscle Rigidity / Q000139:chemically induced* / Q000503:physiopathology / Q000517:prevention & control; D009129:Muscle Tonus / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage / Q000494:pharmacology*; D011229:Preanesthetic Medication; D011446:Prospective Studies; D016037:Single-Blind Method; D013874:Thiopental / Q000008:administration & dosage / Q000494:pharmacology; D014403:Tubocurarine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology
D006993:Hypnotics and Sedatives; D003473:Neuromuscular Nondepolarizing Agents; D015760:Alfentanil; D001279:Atracurium; D013874:Thiopental; D003975:Diazepam; D008874:Midazolam; C032943:metocurine; D014403:Tubocurarine