[Intubation conditions: importance of the rate of repetition of the train-of-four].
OBJECTIVE
To assess that neuromuscular relaxation onset of the adductor pollicis (AP) is related to neuromuscular stimulation rate. To assess that train-of-four (TOF) at 0.05 Hz is a more accurate indicator of optimal tracheal intubation time and conditions, than TOF at 0.08 Hz.


METHODS
Prospective, comparative, randomized double-blind study.


METHODS
Forty adults, physical class ASA 1 or 2, undergoing general anaesthesia with tracheal intubation were allocated to two groups (n = 20) according to the sequence of stimulation of the AP: either TOF at 0.05 Hz (test group) or TOF at 0.08 Hz (control group).


METHODS
Induction of anaesthesia was achieved with thiopentone, fentanyl and vecuronium (0.1 mg.kg-1). Neuromuscular monitoring was obtained with force displacement transducers attached to each AP. Tracheal intubation was performed once AP muscular response obtained with TOF at 0.05 Hz for test group and TOF at 0.08 Hz for control group was abolished. Results are expressed as mean +/- SEM. Fisher exact test was used for intubation conditions comparison. Curarization time between groups was compared with unpaired Student's t test (P < 0.05 accepted).


RESULTS
TOF with 0.05 Hz stimulation significantly increased curarization time: 217 +/- 7 versus 162 +/- 6 s (P < 0.001). Intubation conditions were excellent in 95% and good in 5% of patients in the study group, compared to 15 and 40% in the control group, respectively (P < 0.01) in 45% of the control group patients coughing at intubation occurred.


CONCLUSIONS
Low stimulation rate (TOF at 0.05 Hz) of AP is a reliable technique to determine the appropriate intubation time for patients paralyzed with vecuronium.
de Quattro
A
A
Service d'anesthésiologie, centre hospitalier universitaire Vaudois, CH-1011 Lausanne.
Gardaz
J P
JP
Bissonnette
B
B
D006801:Humans; D007442:Intubation, Intratracheal; D016343:Monitoring, Intraoperative; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D004561:Transcutaneous Electric Nerve Stimulation; D014673:Vecuronium Bromide / Q000494:pharmacology*
D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide