Neuromuscular blockade can be assessed accelerographically over the vastus medialis muscle in patients positioned prone.
OBJECTIVE
To study accelerographic monitoring of neuromuscular blockade over the vastus medialis muscle in anesthetized patients in the prone position.


METHODS
Sixty adult patients were divided into four groups of 15: prone (P)-post-tetanic count (PTC), P-train-of-four (TOF), supine (S)-PTC or S-TOF group. In the P-PTC and P-TOF groups, the muscular branch of the femoral nerve was stimulated and the movement of the vastus medialis muscle was measured accelerographically. In the S-PTC and S-TOF groups, the depth of neuromuscular blockade was assessed mechanically at the thumb. After administration of vecuronium 0.1 mg.kg(-1), TOF stimuli were delivered every 20 sec in all groups. Onset of neuromuscular blockade (time from vecuronium to the minimum level of T1 (first response of TOF) was compared between the P-PTC or P-TOF group and S-PTC or S-TOF group. Recoveries of PTC and those of TOF were compared between the P-PTC and S-PTC groups and P-TOF and S-TOF groups, respectively.


RESULTS
Onset of neuromuscular blockade in the P-PTC or P-TOF group was shorter than in the S-PTC or S-TOF group (132 +/- 43 vs 233 +/- 40 sec, mean +/- SD, P < 0.001). Recoveries of PTC in the P-PTC and S-PTC groups followed a similar time course. Recoveries of T1/control in the P-TOF and S-TOF groups were also comparable. In contrast, train-of-four ratio (T4/T1, TOFR) in the P-TOF group was higher than in the S-TOF group 60-120 min after vecuronium (P < 0.05).


CONCLUSIONS
The degree of neuromuscular blockade can be assessed accelerographically over the vastus medialis muscle even when patients are in the prone position. When evaluated accelerographically over the vastus medialis muscle, onset of neuromuscular blockade is quicker and TOFR is higher than that assessed at the thumb.
Saitoh
Yuhji
Y
Department of Anesthesiology, Fukushima Medical University School of Medicine, Hikarigaoka 1, Fukushima-City, Fukushima 960-1295, Japan. ys@m6.people.or.jp
Nakajima
Hiroshi
H
Hattori
Hisashi
H
Aoki
Kenichi
K
Katayama
Takaaki
T
Murakawa
Masahiro
M
D000704:Analysis of Variance; D016903:Drug Monitoring / Q000706:statistics & numerical data; D004558:Electric Stimulation; D005260:Female; D005267:Femoral Nerve / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000187:drug effects*; D019148:Neuromuscular Blockade; D003473:Neuromuscular Nondepolarizing Agents / Q000627:therapeutic use*; D016684:Prone Position / Q000502:physiology; D013514:Surgical Procedures, Operative; D013848:Thigh; D013997:Time Factors; D014673:Vecuronium Bromide / Q000627:therapeutic use*
D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide