Comparison of neuromuscular blockade in upper facial and hypothenar muscles

Abstract

Facial and hand muscles are used frequently for monitoring neuromuscular blockade. Therefore, we compared changes in electrically evoked muscle potential magnitude in upper facial and hypothenar muscles after fixed doses of neuromuscular blockers (succinylcholine, 750 micrograms/kg; pancuronium, 70 micrograms/kg; vecuronium, 50 micrograms/kg; and atracurium, 300 micrograms/kg). Face-hand comparisons were made in both anesthetized (nitrous oxide/narcotic, n = 51) and comatose (closed-head injuries, n = 5) patients. In 24 anesthetized patients, complete blockade of the hypothenar muscles prevented quantitative comparison. In the remaining 27 patients, the relaxant effect (as determined by the percentage change from prerelaxant baseline muscle potentials) was significantly smaller (P less than 0.0001) in the upper facial muscles (65 +/- 24% versus 92 +/- 8%, mean +/- SD). All four evoked muscle responses to train-of-four stimulation were detectable in upper facial muscles of the 19 patients receiving non-depolarizing neuromuscular blocking drugs; this pattern was seen in hand muscles of only 7 patients (P less than 0.001). The neuromuscular blockade in both the hand (49 +/- 54%) and the upper facial area (68 +/- 28%, P greater than 0.05) of comatose patients was smaller and more variable than that seen during anesthesia. These results illustrate the value of quantitative monitoring of neuromuscular function, especially during highly variable and unpredictable drug-induced blockade in the comatose state. We conclude that during narcotic-based anesthesia the upper facial and hand muscles are differentially sensitive to commonly used neuromuscular blockers.

Time‐frequency balanced spectral entropy as a measure of anesthetic drug effect in central nervous system during sevoflurane, propofol, and thiopental anesthesia

“…Electrical activity of the upper facial muscles is of rather high frequency, mostly above 32 Hz (17). Nociception typically activates these muscles, causing the amplitude of FEMG to increase, and they are very resistant to NMBAs (18). Frontal electromyogram activation due to strong nociceptive stimulation is measurable during a 80-90% neuromuscular block in electrically evoked hypothenar EMG responses (19), and even during 100% hypothenar block (20).…”

Auditory steady-state response, upper facial EMG, EEG and heart rate as predictors of movement during isoflurane-nitrous oxide anaesthesia

“…Several studies have documented the relative insensitivity of the upper facial muscles to nondepolarizing neuromuscular block [31,32]. These muscles remain responsive even when the electrically evoked thenar EMG response has been depressed by 90% from pre-block baseline values [7].…”

Phonomyographic measurements of neuromuscular blockade are similar to mechanomyography for hand muscles

“…Several intrinsic hand muscles can be used to monitor NMB of the patient, mainly the adductor pollicis muscle, but also the hypothenar and first dorsal interosseus muscles. 3,4 Because of different innervation, blood perfusion and tissue composition, these muscles are prone to different responses to non-depolizaring agents. The goal of this study was to compare measurements of NMB after rocuronium 0.6 mg•kg -1 at all three muscle sites of the hand (first dorsal interosseus, the hypothenar muscles, and the thenar muscle group) using PMG with measurements of NMB at the adductor pollicis muscle using mechanomyography (MMG).…”