Simultaneous determination of neuromuscular block at the larynx, diaphragm, adductor pollicis, orbicularis oculi and corrugator supercilii muscles

We simultaneously determined the neuromuscular blocking effectof mivacurium 0.2 mg kg^–1 at five muscles in 20 womenundergoing gynaecological surgery. Evoked electromyographicresponses were obtained using surface electromyography (EMG)at the adducting laryngeal muscles, the diaphragm (lateral tovertebrae T12/L1 or L1/L2) and the adductor pollicis muscleand acceleromyographic (AMG) responses were measured at theorbicularis oculi and the corrugator supercilii muscle. Onsettime and times for the first twitch response (T₁/T₀) to returnto 25, 75 and 90% at the adducting laryngeal muscles and thediaphragm were significantly (P<0.005) shorter than at theadductor pollicis, the corrugator supercilii or the orbicularisoculi muscles (mean (SD) onset time: 89 (26) s and 78 (17) sto 202 (45) s, 152 (41) s, 194 (40) s; T₁/T₀=25%: 10.4 (1.5)and 11.4 (1.2) min versus 20.5 (3.9), 15.9 (3.3), 16.3 (3.7)min; T₁/T₀=90%: 15.5 (1.6) and 16.1 (1.6) min versus 27.4 (4.6),21.5 (3.8), 23.3 (5.1) min). Onset and clinical duration ofneuromuscular block at the larynx and the diaphragm after mivacurium0.2 mg kg^–1 are shorter than in the peripheral muscles.Monitoring of neuromuscular block in the diaphragm was successfullyused in all patients. Br J Anaesth 2000; 85: 856–60     

The corrugator supercilii, not the orbicularis oculi, reflects rocuronium neuromuscular blockade at the laryngeal adductor muscles

BACKGROUND: Some studies suggest that the orbicularis oculi is resistant to neuromuscular blocking drugs and behaves like laryngeal muscles. Others report little or no difference between the orbicularis oculi and the adductor pollicis. These discrepancies could be related to the exact site of recording. The purpose of this study was to compare two monitoring sites around the eye with the adductor pollicis and the laryngeal adductor muscles. METHODS: After institutional approval and informed consent, the evoked response to train-of-four stimulation was measured in 12 patients by acceleromyography at the thumb (adductor pollicis), the eyelid (orbicularis oculi), and the superciliary arch (corrugator supercilii) after 0.5 mg/kg rocuronium during propofol-fentanyl-nitrous oxide anesthesia. In 12 other patients, laryngeal adductor neuromuscular blockade was assessed via the cuff of the tracheal tube and compared with the adductor pollicis and the corrugator supercilii after 0.6 mg/kg rocuronium. RESULTS: After 0.5 mg/kg, maximum blockade (%T1, mean +/- SD) was less at the corrugator supercilii (80+/-20%) than at the adductor pollicis (100+/-1%) and the orbicularis oculi (93+/-8%) (P < 0.01). Clinical duration (25%T1) was shorter at the corrugator supercilii (12+/-7 min) than at the adductor pollicis (25+/-4 min) and orbicularis oculi (24+/-10 min) (P < 0.01). After 0.6 mg/kg, maximum blockade was similar at the corrugator supercilii (88+/-8%) and the laryngeal adductor muscles (89+/-11%). Clinical duration at the corrugator supercilii and the laryngeal adductors was 17+/-7 and 17+/-10 min, respectively. CONCLUSIONS: Muscles around the eye vary in their response to rocuronium. The response of the superciliary arch (corrugator supercilii) reflects blockade of laryngeal adductor muscles. However, the eyelid (orbicularis oculi) and thumb (adductor pollicis) have similar sensitivities.     

Infusion requirements and reversibility of rocuronium at the corrugator supercilii and adductor pollicis muscles

Background: The aim of this study is to compare the infusion rates required to maintain a constant neuromuscular block and the reversibility of rocuronium at the corrugator supercilii muscle (CSM) and the adductor pollicis muscle (APM).
Methods: We randomly allocated 30 female patients into two groups of 15 patients each to monitor neuromuscular block at either the CSM or the APM. After induction of anaesthesia and laryngeal mask insertion, contraction of the CSM to the facial nerve stimulation or that of the APM to the ulnar nerve stimulation was quantified using an acceleromyograph during 1.0–1.5% end-tidal sevoflurane anaesthesia. All the patients received a bolus of 1 mg/kg rocuronium. When the first twitch (T1) of train-of-four (TOF) recovered to 10% of the control, rocuronium infusion was commenced and maintained at T1 of 10% of the control at the CSM or APM for 120 min. Immediately after rocuronium infusion was discontinued, the time required for 0.04 mg/kg neostigmine-facilitated recovery to a TOF ratio of 0.9 was recorded.
Results: Rocuronium infusion dose after a lapse of 120 min was significantly larger in the CSM than in the APM [7.1 (2.3) vs. 4.7 (2.6) μg/kg/min; P =0.001]. The time for facilitated recovery was shorter in the CSM than in the APM [11.4 (3.8) vs. 16.2 (6.0) min; P =0.016].
Conclusion: A larger rocuronium infusion dose was required to maintain a constant neuromuscular block at the CSM. Neostigmine-mediated reversal was faster at the CSM.     

Blood flow and mivacurium-induced neuromuscular block at the orbicularis oculi and adductor pollicis muscles

We have studied the pattern of blood flow and pharmacodynamic profile of mivacurium-induced block at the adductor pollicis and orbicularis oculi muscles. We studied 30 adult patients anaesthetized with fentanyl, thiopentone, nitrous oxide-isoflurane, and mivacurium 0.2 mg kg-1. Neuromuscular transmission was monitored with accelerometry (TOF Guard, Biometer, Denmark). Blood flow was measured at the two muscles with the use of a laser Doppler flowmeter (Laserflo BPM2, Vasamedics, USA). All patients developed 100% neuromuscular block at the adductor pollicis muscle. Mean maximum neuromuscular block at the orbicularis oculi was 96.4 (SD 3.5)% (ns). Onset time, time required for 25% and 75% recovery of the first twitch in the train-of-four (T1), and a train- of-four ratio (T4/T1) of 90% at the orbicularis oculi were respectively, mean 130.4 (SD 28.5) s, 9.1 (3.2) min, 16.2 (3.9) min and 20.2 (4.3) min and were significantly shorter than the corresponding values at the adductor pollicis: 202.7 (37.2) s, 12.9 (3.9) min, 21.1 (5.1) min and 30.8 (7.4) min. For a given T1, there was significantly less train-of-four fade (T4/T1) at the orbicularis oculi than at the adductor pollicis muscle during recovery. Blood flow was comparable at the two muscles before induction of anaesthesia. Thiopentone significantly increased thenar muscle blood flow from 2.9 (1.5) to 12.3 (6.8) ml 100 g-1 min-1, with a further increase to 22.7 (8.0) ml 100 g- 1 min-1 after isoflurane (P < 0.001). Blood flow at the orbicularis oculi was not altered by thiopentone or isoflurane and was consistently lower than that at the adductor pollicis muscle. We conclude that the different pharmacodynamic profiles of mivacurium-induced block at the orbicularis oculi and adductor pollicis muscles were not related primarily to a difference in blood flows.      

TOF count at corrugator supercilii reflects abdominal muscles relaxation better than at adductor pollicis

Background: A recovery profile from neuromuscular block similar to thatof abdominal (AB) muscles, but different to that of the adductorpollicis (AP) muscle, has been demonstrated at the corrugatorsupercilii (CSC) muscle. We hypothesized that neuromusculartransmission (NMT) monitoring of CSC might provide useful informationon AB relaxation compared with AP. We compared the visual estimationof NMT at CSC and AP with electromyographic measurements ofAB during recovery from a vecuronium block. Methods: Ten adult patients were studied during balanced anaesthesia.After induction of anaesthesia and tracheal intubation withoutneuromuscular blocking agents, supramaximal stimulations wereapplied to three nerves: left 10th intercostal, ulnar, and facial.Electromyographic activity (EMG) of AB was measured (ABEMG).After a bolus dose of vecuronium 0.1 mg kg^–1, an independentobserver blinded to the EMG measurements counted visually detectabletrain-of-four (TOF) responses at CSC and AP. Values of ABEMGassociated with 1 to 4 TOF responses at CSC and AP were compared.Values are means (SD). Results: Reappearance of the first and second TOF responses at CSC occurredsignificantly (P < 0.05) earlier and at lower ABEMG recoverythan that of AP [35 (8) and 41 (9) min vs 51 (10) and 56 (12)min; and 17 (8) and 26 (9)% vs 56 (10) and 75 (11)%, respectively]. Conclusions: We demonstrated that the TOF response count at the CSC, comparedwith the AP, allowed a better quantification of the degree ofAB muscle relaxation during recovery from vecuronium block.     

Vecuronium neuromuscular blockade at the diaphragm, the orbicularis oculi, and adductor pollicis muscles

To determine the relationship among diaphragm, orbicularis oculi, and adductor pollicis blockade, train-of-four stimulation was applied to the phrenic, facial, and ulnar nerves in 16 adult patients anesthetized with alfentanil-propofol-oxygen. Vecuronium 0.04 or 0.07 mg/kg was given. The response of the adductor pollicis was measured with a force transducer, and that of the other muscles by electromyography (EMG). No statistically significant differences were detected with either dose in the intensity of maximum blockade measured at the three muscles. With 0.04 mg/kg, the first response (T1) in the train-of-four was decreased (mean +/- SEM) 78 +/- 8, 62 +/- 11, and 84 +/- 3% for the diaphragm, orbicularis oculi, and adductor pollicis, respectively. Corresponding values after 0.07 mg/kg were 95 +/- 3, 82 +/- 11, and 95 +/- 2%, respectively. However, onset time was longer at the adductor pollicis than at the diaphragm, and the orbicularis oculi onset time approached that of the diaphragm. With 0.04 mg/kg, time to maximum diaphragmatic blockade was 2.9 +/- 0.3 min, compared with 3.7 +/- 0.6 min at the orbicularis oculi (no significant difference [NS]) and 6.6 +/- 0.4 min at the adductor pollicis (P less than 0.001). With vecuronium 0.07 mg/kg the values were 2.2 +/- 0.3, 3.4 +/- 0.5 (P = 0.024), and 6.3 +/- 0.6 (P less than 0.001), respectively. Time to 75% T1 recovery was similar at the diaphragm and the orbicularis oculi, but significantly longer at the adductor pollicis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cisatracurium neuromuscular block at the adductor pollicis and the laryngeal adductor muscles in humans

We have compared the dose-response relationship (n = 30) and time course of neuromuscular block (n = 20) of cisatracurium at the laryngeal adductor and the adductor pollicis muscles. ED95 values for cisatracurium were 66.8 (95% confidence interval 61.3-72.3) micrograms kg-1 at the larynx and 45.2 (42.1-48.3) micrograms kg-1 at the adductor pollicis muscle (P < 0.0001). After administration of cisatracurium 0.1 mg kg-1, onset time was 2.7 (2.2-3.2) min at the larynx and 3.9 (3.0- 4.8) min at the adductor pollicis (P < 0.0001). Time to 95% recovery of the first twitch of the TOF was 26.9 (20.1-33.7) min and 45.6 (39.7- 51.5) min, respectively (P < 0.0001). We found that the laryngeal adductors were more resistant to the action of cisatracurium than the adductor pollicis muscle, but onset and recovery were faster at the larynx.      

Onset of neuromuscular block at the masseter and adductor pollicis muscles following rocuronium or succinylcholine

PURPOSE: To compare the onset time of two different rocuronium doses (0.6 and 0.9 mg x kg(-1)) and succinylcholine (1.5 mg x kg(-1), preceeded by 0.06 mg x kg(-1) rocuronium) at the masseter and the adductor pollicis muscle. METHODS: In a randomized study, 60 ASA I or II adult women, 18-65 yr of age, were anesthetized with propofol and fentanyl and nitrous oxide in oxygen. Neuromuscular monitoring was performed using acceleromyography simultaneously on the masseter and adductor pollicis. Onset time was measured at both muscles using supramaximal 0.1 Hz single twitch stimulation (square-wave pulse 0.2 msec duration). RESULTS: In all patients, complete neuromuscular block occurred at the masseter and adductor pollicis muscles. Lag-time and onset time were faster at the masseter that at the adductor pollicis muscle in both rocuronium-groups (P < 0.01) and in the succinylcholine-group (P < 0.01). Furthermore, onset time was more rapid after 0.9 mg x kg(-1) rocuronium (65 +/- 7 s) than after succinylcholine (83 +/- 19 sec) at the AP (P < 0.05), but did not differ at the masseter (33 +/- 6 vs 36 +/- 7 sec). CONCLUSIONS: Following rocuronium and succinylcholine, onset time is faster at the masseter than at the adductor pollicis muscle.     

Vecuronium neuromuscular blockade at the adductor muscles of the larynx and adductor pollicis.

The differences between neuromuscular blockade of the adductor muscles of the vocal cords and the adductor pollicis were examined in 20 adult women anesthetized with fentanyl and propofol. Vecuronium 0.04 or 0.07 mg/kg was given as a single bolus by random allocation. The force of contraction of the adductor pollicis was recorded. Laryngeal response was measured as pressure changes in the cuff of the tracheal tube positioned between the vocal cords. Train-of-four stimulation was applied to the recurrent laryngeal nerve at the notch of the thyroid cartilage and to the ulnar nerve at the wrist. Neuromuscular blockade had a faster onset, was less intense, and recovered more rapidly at the vocal cords. With 0.04 mg/kg, maximum blockade of first twitch (T1) was 55 +/- 8 (mean +/- standard error of the mean [SEM]) and 88 +/- 4% at the vocal cords and the adductor pollicis, respectively (P = 0.006). Onset time was 3.3 +/- 0.1 and 5.7 +/- 0.2 min, respectively (P = 0.000001), and time to 90% T1 recovery was 11.3 +/- 1.6 and 26.1 +/- 1.8 min, respectively (P = 0.001). With 0.07 mg/kg, onset time was unchanged; maximum blockade was more intense, being 88 +/- 4 and 98 +/- 1%, respectively (P = 0.04 between muscles); and time to 90% T1 recovery was 23.3 +/- 1.8 min at the vocal cords versus 40.3 +/- 2.9 min at the adductor pollicis (P = 0.001). Approximately 1.73 times as much vecuronium was required at the larynx compared with the dose required at the adductor pollicis for the same intensity of blockade.(ABSTRACT TRUNCATED AT 250 WORDS)     

Post-tetanic count at adductor pollicis is a better indicator of early diaphragmatic recovery than train-of-four count at corrugator supercilii

Background: Because the intensity of neuromuscular block at the diaphragm(DIA) is indirectly assessed, the electromyographic measurementsof the DIA (DIA_EMG) from surface electrodes were related toinformation provided by visual estimation of neuromuscular transmissionat the adductor pollicis (AP) and the corrugator supercilii(CSC) during recovery from vecuronium block. Methods: Twelve adult patients were studied during balanced anaesthesia.After induction of anaesthesia and tracheal intubation withoutneuromuscular blocking agent, supramaximal stimulations wereapplied to phrenic, ulnar and facial nerves. During recoveryfrom vecuronium 0.1 mg kg^–1 an independent observer blindedto DIA_EMG counted visually detectable train-of-four (TOF) atCSC (TOF_CSC) and post-tetanic AP (PTC_AP) responses. Times torecovery of PTC_AP = 1, 5, <10 and >10, and TOF_CSC = 1–4responses were related to DIA_EMG. Values are means (SD). Results: Reappearance of the first response to PTC_AP occurred significantly(P < 0.05) earlier and for a lower recovery of DIA_EMG thanthat of TOF_CSC [24 (8) min vs 33 (9) min, and 10 (10)% vs 25(8)%, respectively]. With PTC_AP 5 response, DIA_EMG recoverywas 21 (11)%. Recovery of TOF_CSC = 1 and 2 coincided with DIA_EMGrecovery of 25 (8)% and 47 (9)%, respectively. Conclusions: PTC_AP may better reflect early recovery of vecuronium-inducedDIA paralysis than TOF_CSC. The findings suggested that PTC_AP 5 warranted deep neuromuscular block of the DIA.     

Comparison of cisatracurium-induced neuromuscular block at the masseter and adductor pollicis muscle

Adequate relaxation of the masseter muscle is important during endotracheal intubation and for the patency of a patient's airway during recovery from anaesthesia. We evaluated onset and recovery from cisatracurium-induced neuromuscular block at the masseter and adductor pollicis muscles. Thirty patients were randomly allocated to receive either 0.1 or 0.15 mg kg(-1) cisatracurium. The evoked response was measured at both muscles using acceleromyography. Onset time was significantly shorter at the masseter muscle than at the adductor pollicis (0.1 mg kg(-1) cisatracurium: 155+/-52 vs. 229+/-44 s; 0.15 mg kg(-1) cisatracurium: 105+/-24 vs. 174+/-35 s). Following 0.1 mg kg(-1) cisatracurium, recovery to a TOF-ratio of 0.7 was faster at the masseter compared to the adductor pollicis (P < 0.05). In the 0.15 mg kg(-1) cisatracurium group recovery of T1 to 75% of control and to a TOF-ratio of 0.7 occurred sooner at the masseter (P < 0.05). We conclude that onset and recovery from cisatracurium neuromuscular block occurs more rapidly at the masseter than at the adductor pollicis. It appears unlikely that residual paralysis is present at the masseter once neuromuscular function at the adductor pollicis has completely recovered.     

Acceleromyography of the orbicularis oculi muscle II: comparing the orbicularis oculi and adductor pollicis muscles

BACKGROUND: The orbicularis oculi (OO) muscle has been recommended for neuromuscular monitoring when the adductor pollicis (AP) muscle is not available. We investigated whether neuromuscular block could be measured reliably from the orbital part of the OO muscle by the use of acceleromyography. METHODS: During propofol, fentanyl, and alfentanil anaesthesia two TOF-Guards (Organon Teknika NV, Boxtel, the Netherlands) with acceleration transducers placed on the distal phalanx of the thumb and over the middle of the eyebrow, respectively, were used to measure neuromuscular block simultaneously in 23 patients during vecuronium-induced and neostigmine-antagonized neuromuscular block. For both muscles, the simultaneously recorded first response (T1) in the train-of-four (TOF) and TOF-ratio were measured both during onset and recovery of the block. Furthermore, both the AP muscle T1 and TOF-ratio responses were plotted against 10% intervals of the OO muscle responses during onset and recovery, respectively. RESULTS: The orbicularis oculi muscle had a shorter latency and a faster recovery to TOF-ratio 0.80 compared with the AP muscle. During onset and recovery, pronounced variations of the AP muscle T1 and TOF-ratio responses were observed when compared with the OO muscle. CONCLUSION: A significant clinical disagreement exists between the degree of paralysis measured at the OO and the AP muscles. It is impossible to obtain a reasonable estimate of the degree of block at the AP muscle when the block is measured from the OO muscle with acceleromyography. If used, there is substantial risk of overlooking a residual block, and adequate recovery of the block should be confirmed by a final AP muscle measurement.     

Neostigmine-induced neuromuscular blockade in the corrugator supercilii muscle

ObjectiveTo investigate whether a single dose of neostigmine, administered when the adductor pollicis muscle presents 2 twitches in train-of-four (TOF) stimulation, can reduce the TOF ratio in the corrugator supercilii muscle.Patients and methodsWe designed a case-control study of patients between 18 and 65 years of age classified ASA 1-2. We used 2 accelerometers—1 for the cubital nerve/thumb adductor muscle and 1 for the facial nerve/corrugator supercilii muscle. Neuromuscular blockade was induced with 0.6 mg·kg^-1 of rocuronium, and 40 µg·kg^-1 of neostigmine was administered at the third twitch in the TOF in the thumb adductor. If the TOF ratio in the corrugator supercilii fell by 10% or more at that time, the patient was classified as a case. We recorded the age, sex, weight, height, body mass index, duration of the procedure, and TOF ratio in the corrugator supercilii muscle when the neostigmine was administered.ResultsTen cases and 10 controls were enrolled. No significant differences between cases and controls were found in any variables except the mean (SD) TOF ratio in the corrugator supercilii muscle: 70.9% (17.8%) in cases and 35.3% (7.8%) in controls (P<.001).ConclusionsIn our patients, administration of neostigmine after the appearance of the third twitch in TOF stimulation of the thumb adductor was associated with a reduction in the TOF ratio in the corrugator supercilii. The similarity between blockades of the corrugator muscle, the diaphragm, and the larynx is of clinical interest.     

Rocuronium (ORG 9426) neuromuscular blockade at the adductor muscles of the larynx and adductor pollicis in humans

The effects of rocuronium, 0.25 or 0.5 mg.kg-1, were measured simultaneously on the adductor muscles of the larynx and adductor pollicis in 14 adult patients. Anaesthesia was induced and maintained with propofol and fentanyl. Tracheal intubation was performed without muscle relaxants. The recurrent laryngeal and ulnar nerves were both stimulated supramaximally, at the notch of the thyroid cartilage and at the wrist respectively, using train-of-four stimulation. The laryngeal response was evaluated by measuring the pressure change in the cuff of a tracheal tube positioned between the vocal cords. Onset time, intensity of blockade and duration of action were less at the larynx than at the adductor pollicis. After rocuronium, 0.25 mg.kg-1, the onset time (interval between injection and maximal T1 blockade) was 1.6 +/- 0.1 min and 3.0 +/- 0.3 min (mean +/- SEM) at the laryngeal muscles and adductor pollicis, respectively (P less than 0.01 between muscles). Maximum blockade was 37 +/- 8% and 69 +/- 8%, respectively (P less than 0.05), and time to 90% T1 recovery was 7 +/- 1 min and 20 +/- 4 min, respectively (P less than 0.05). With 0.5 mg.kg-1, the onset time was also more rapid at the vocal cords (1.4 +/- 0.1 min) than at the adductor pollicis (2.4 +/- 0.2 min, P less than 0.001). Maximum blockade was 77 +/- 5% and 98 +/- 1%, respectively (P less than 0.01), and time to 90% T1 recovery was 22 +/- 3 min and 37 +/- 4 min, respectively (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Temporal relation between acoustic and force responses at the adductor pollicis during nondepolarizing neuromuscular block

BACKGROUND: Contracting muscle emits sounds. The purpose of this study was to compare the time course of muscular paralysis at the adductor pollicis muscle (AP) with use of acoustic myography and mechanomyography. METHODS: Thirteen elective surgery patients, American Society of Anesthesiologists physical status I, received rocuronium (0.6 mg/kg intravenously) as a bolus dose during general anesthesia. Force of AP was measured with use of a strain gauge, and sounds were recorded simultaneously with use of a small condenser microphone fixed on the palmar surface of the hand over the AP. Supramaximal stimulation was applied to the ulnar nerve at 0.1 Hz for 45-60 min. In seven patients, the response to train-of-four stimulation was also recorded during recovery. RESULTS: Force and sounds both were equally sensitive in measuring maximum block. The relation between sound and force was curvilinear, with good agreement near 0 and 100% and acoustic response exceeding mechanical response at intermediate levels of block. The acoustic signal had a slower onset and a faster recovery than the force response. The fade response of sound to train-of-four stimulation also recovered faster than that of force. CONCLUSION: Acoustic myography is an alternative method to monitor muscular paralysis that is easy to set up and applicable to most superficial muscles. However, the time course of relaxation at AP using acoustic myography differs from the time course of force relaxation. Therefore, these two methods are not equivalent when applied to AP.     

Phonomyography and mechanomyography can be used interchangeably to measure neuromuscular block at the adductor pollicis muscle

The standard of neuromuscular monitoring is the measurement of the force of contraction (mechanomyography, MMG). Phonomyography (PMG) consists of recording low-frequency sounds created during muscle contraction. In this study, we compared and used both methods to determine neuromuscular blockade (NMB) at the adductor pollicis muscle. In 14 patients, PMG was recorded via a small condenser microphone taped to the thenar mass, and a standard mechanomyographic device was applied to the same arm. In another group of 14 patients, only PMG was measured. After induction of anesthesia, the ulnar nerve was stimulated supramaximally using single twitch stimulation (0.1 Hz) for onset and train-of-four (TOF) stimulation every 12 s during offset of NMB produced by mivacurium 0.1 mg/kg. Onset and recovery indices measured by the 2 methods were compared using Student's t-test (P < 0.05). Similar comparisons were made between the two PMG groups (with or without special board). Agreement between PMG and MMG was examined using a Bland-Altman test. Onset was 165 (68) s versus 172 (67) s [mean (SD)], and maximum blockade was 89 (10)% versus 90 (11)%, for PMG and MMG respectively (NS). Time to 25%, 75%, and 90% recovery was 16.5 (4.2) min, 22.1 (6.9) min, and 24.5 (8.2) min, respectively for PMG, not different from 16.7 (4) min, 22.8 (8.1) min, and 24.8 (8.8) min for MMG. Mean bias was 0% with limits of agreement of -10 and + 10% of twitch height for all signals (MMG minus PMG). Time to TOF of 0.5, 0.7, 0.8, and 0.9, was 1 min faster with PMG than with MMG, with limits of agreement of -1.5 to 3.5 min. Pharmacodynamic data derived without or with special arm fixation were not significantly different. MMG and PMG can be used interchangeably to determine NMB at the adductor pollicis muscle. PMG is easier to apply, does not need a special monitoring board and could be a reliable monitor to determine NMB in daily routine. IMPLICATIONS: Mechanomyography and phonomyography (PMG), a novel method of monitoring neuromuscular blockade (NMB) by recording low-frequency sounds emitted by muscle contraction, can be used interchangeably to determine NMB at the adductor pollicis muscle. PMG is easier to apply, does not need a special monitoring board and could be a reliable monitor to determine NMB in daily routine.     

The staircase phenomenon at the corrugator supercilii muscle in comparison with the hand muscles

Background. Phonomyography (PMG) is a novel method to monitorneuromuscular block. It is non-invasive and can be applied toany muscle. It can be used interchangeably with mechanomyography(MMG). The staircase phenomenon has not been investigated forthis method or at the corrugator supercilii muscle. The purposeof this work was to determine the staircase effect at threedifferent muscles using two different methods. Methods. In 10 patients undergoing general anaesthesia withsevoflurane, using a laryngeal mask airway without the aid ofneuromuscular block, one piezo-electric microphone each wasapplied to the corrugator supercilii muscle and the first dorsalinterosseus muscle. In addition, a force transducer was attachedto the tip of the thumb to determine the force of the adductorpollicis muscle. Supramaximal stimulation at 1 Hz was used atthe ulnar and the facial nerve. All signals were simultaneouslyrecorded for 30 min. Data are presented as means (SD). Results. The staircase effect was significantly positive forthe first dorsal interosseus muscle and the adductor pollicismuscle. The signal potentiation was not significantly differentbetween the first dorsal interosseus muscle with a maximum increaseat 148 (19)% using PMG, and the adductor pollicis muscle at154 (22)% using MMG. The evoked signals reached a plateau after15–18 min at both muscles. There was only a small initialincrease in signal height at the corrugator supercilii to amaximum of 117 (20)% at 7 min, after which the signals decreasedto reach a plateau at 25 min. In comparison with the signalheight of 105 (25)% at 30 min, there was no significant differenceof signal heights throughout the observation period. Conclusions. A positive staircase phenomenon is found equallyat the first dorsal interosseus muscle and the adductor pollicismuscle. There is no significant staircase effect at the corrugatorsupercilii muscle.      

不同剂量顺式阿曲库铵对患者拇内收肌与眼轮匝肌肌松效应的比较

目的 比较不同剂量顺式阿曲库铵对患者拇内收肌与眼轮匝肌的肌松效应.方法 全麻患者25例,ASA Ⅰ或Ⅱ级,年龄42～64岁,体重51～81 kg,随机分为2组,顺式阿曲库铵0.075ms/ks组(Ⅰ组,n=11)和顺式阿曲库铵0.15 mg/kg组(Ⅱ组,n=14).静脉注射咪达唑仑0.035～0.045mg/kg、异丙酚1.5～2 mg/kg、芬太尼0.1～0.2 mg、顺式阿曲库铵0.075 mg/kg或0.15 mg/kg行麻醉诱导,吸入50%氧化亚氮、间断静脉注射芬太尼维持麻醉.采用2台TOF-Watch SX加速度肌松监测仪同步监测眼轮匝肌和拇内收肌的神经肌肉阻滞情况,记录肌松起效时间、无反应期及T25%和T75%恢复时间.于眼轮匝肌肌颤搐抑制75%～80%时行气管插管,并评价气管插管条件.结果 2组气管插管条件良好且差异无统计学意义(P>0.05);与Ⅰ组比较,Ⅱ组拇内收肌和眼轮匝肌肌松起效时间缩短,T25%恢复时间、T75%恢复时间和无反应期延长(P<0.01);与拇内收肌比较,Ⅰ组眼轮匝肌T75%恢复时间缩短,Ⅱ组眼轮匝肌无反应期和T25%恢复时间缩短(P<0.05或0.01).结论 顺式阿曲库铵对拇内收肌和眼轮匝肌的肌松效应呈剂量依赖性,眼轮匝肌对顺式阿曲库铵的敏感性低于拇内收肌;监测顺式阿曲库铵对眼轮匝肌神经肌肉阻滞情况可有效指导气管插管.