Influence of nondepolarizing muscle relaxants on intraoperative neuromonitoring during thyroid surgery.
OBJECTIVE
The objective of this study was to find a nondepolarizing muscle relaxant to replace succinylcholine during thyroid surgery with intraoperative neuromonitoring (IONM) because succinylcholine can cause severe adverse effects.


METHODS
Prospective study of 232 patients undergoing thyroidectomies.


METHODS
A tertiary medical centre.


METHODS
One hundred thirty-one patients received 0.5 mg/kg rocuronium (group R) and 101 patients received 0.5 mg/kg atracurium (group A) to facilitate electromyographic (EMG) endotracheal tube insertion. EMG signals were obtained from the vagus nerve before and after dissection of the recurrent laryngeal nerve and were defined as the V1 and the V2 signal, respectively. Accelerometry (twitch [% TW]) was used to monitor the quantitative degree of neuromuscular transmission at the adductor pollicis muscle.


METHODS
The amplitude (muV) of the V1 and V2 signals and the correlated degree of neuromuscular transmission (% TW).


RESULTS
V1 and V2 signals were obtained from all patients successfully. The % TW at the V1 signal was significantly lower than that at the V2 signal in group R and group A. The mean recovery time from complete neuromuscular blockade to the initial twitch was 43.9 +/- 11 minutes. Only in the subgroup in which the correlated TW was 0% while eliciting the V1 signal were the amplitudes of the V1 signals significantly lower than those of the V2 signal in both groups.


CONCLUSIONS
A single dose (0.5 mg/kg) of rocuronium and atracurium was feasible for IONM during thyroid surgery. This study showed that 44 minutes after administration of these two muscle relaxants is adequate for eliciting an EMG signal from the vagus nerve.
Chu
Koung-Shing
KS
Department of Anesthesiology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
Tsai
Cheng-Jing
CJ
Lu
I-Cheng
IC
Tseng
Kuang-Yi
KY
Chau
Siu-Wah
SW
Wu
Che-Wei
CW
Lee
Ka-Wo
KW
Kuo
Wen-Rei
WR
Chiang
Feng-Yu
FY
D000328:Adult; D000368:Aged; D000732:Androstanols / Q000008:administration & dosage; D000768:Anesthesia, General / Q000379:methods*; D001279:Atracurium / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004576:Electromyography / Q000187:drug effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009469:Neuromuscular Junction / Q000187:drug effects; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage*; D011446:Prospective Studies; D000077123:Rocuronium; D013965:Thyroidectomy / Q000379:methods*; D016896:Treatment Outcome; D014826:Vocal Cord Paralysis / Q000517:prevention & control; D055815:Young Adult
D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D001279:Atracurium; D000077123:Rocuronium