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.     

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.     

Neuromuskuläres Monitoring

The effect of muscle relaxants varies among people and the extent, the duration and recovery from the neuromuscular block varies. Clinical tests cannot determine the effect of muscle relaxants which is only possible with neuromuscular monitoring. The relaxometry procedure measures the muscular response to electrical stimulation of the corresponding motor nerve and the adductor pollicis muscle is mostly used; however, this muscle is not representative for other muscle groups, such as the muscles of the larynx and diaphragm. The muscles of the larynx and diaphragm are more resistant against nondepolarizing muscle relaxants than the adductor pollicis muscle. The train of four (TOF) is used at the beginning of surgery for monitoring of the optimal time for tracheal intubation; moreover, the TOF is used during surgery for monitoring of the muscle blockade and at the end of surgery for monitoring recovery. Monitoring of deep muscular blockades, however, is only possible with the posttetanic count (PTC) when there are no TOF counts. The PTC allows repetition and higher doses of muscle relaxants during abdominal surgery; therefore, conditions for surgery are optimal and cumulation of muscle relaxants is avoided.     

Effects of an intubating dose of succinylcholine and rocuronium on the larynx and diaphragm: an electromyographic study in humans

BACKGROUND: Paralysis of the vocal cords is one objective of using relaxants to facilitate tracheal intubation. This study compares the neuromuscular blocking effect of succinylcholine and rocuronium on the larynx, the diaphragm, and the adductor pollicis muscle. METHODS: Electromyographic response was used to compare the neuromuscular blocking effect of succinylcholine and rocuronium on the laryngeal adductor muscles, the diaphragm, and the adductor pollicis muscle. Sixteen patients undergoing elective surgery were anesthetized with propofol and fentanyl, and their tracheas were intubated without neuromuscular blocking agents. The recurrent laryngeal and phrenic nerves were stimulated at the neck. The electromyographic response was recorded from electrodes placed on the endotracheal tube and intercostally before and after administration of 1 mg/kg succinylcholine or 0.6 mg/kg rocuronium. RESULTS: The maximum effect was greater at the adductor pollicis (100 and 99%) than at the larynx (96 and 97%) and the diaphragm (94 and 96%) after administration of succinylcholine and rocuronium, respectively (P < or = 0.05). Onset time was not different between the larynx (58+/-10 s), the diaphragm (57+/-8 s), and the adductor pollicis (54+/-13 s), after succinylcholine (all mean +/- SD). After rocuronium, onset time was 124+/-39 s at the larynx, 130+/-44 s at the diaphragm, and 115+/-21 s at the adductor pollicis. After succinylcholine administration, time to 90% recovery was 8.3+/-3.2, 7.2+/-3.5, and 9.1+/-3.0 min at the larynx, the diaphragm, and the adductor pollicis, respectively. Time to 90% recovery after rocuronium administration was 34.9+/-7.6, 30.4+/-4.2, and 49.1+/-11.4 min at the larynx, the diaphragm, and the adductor pollicis, respectively. CONCLUSION: Neuromuscular blocking effect of muscle relaxants on the larynx can be measured noninvasively by electromyography. Although the larynx appears to be resistant to muscle relaxants, we could not demonstrate that its onset time differed from that of peripheral muscles.     

Neuromuscular blockade monitoring at the corrugator supercilii and ocular myasthenia gravis

A 67-year-old patient suffering from an ocular myasthenia gravis was scheduled for an elective ENT surgery. General anaesthesia was induced intravenously. Neuromuscular responses after train-of-four stimulation were normal at both the adductor pollicis (T(4)/T(1) = 1) and the corrugator supercilii (4 visual responses). Then cisatracurium (0,15 mg kg(-1)) was administered to allow tracheal intubation. The laryngoscopy attempted 45 s after cisatracurium injection (no response at the supercilii, T(1)/T(0) = 1 at the adductor pollicis) was unsuccessful because of closing and moving vocal cords. The second attempt was successful 4 min after cisatracurium injection (no response at the corrugator supercilii, T(1)/T(0) = 0.05 at the adductor pollicis). Residual neuromuscular blockade was antagonized at the end of surgery (1 h long) allowing an uneventful extubation. We concluded that monitoring neuromuscular blockade at the corrugator supercilii to assess the intubating conditions is not recommended in a case of ocular myasthenia gravis.     

Brief review: Neuromuscular monitoring: an update for the clinician

PURPOSE: To review established techniques and to provide an update on new methods for clinical monitoring of neuromuscular function relevant to anesthesia. SOURCE: A PubMed search of relevant article for the period 1985-2005 was undertaken, and bibliographies were scanned for additional sources. PRINCIPAL FINDINGS: There is no substitute for objective neuromuscular monitoring; for research purposes, mechanomyography (MMG) is the gold standard; however, the most versatile method in the clinical setting is acceleromyography since it can be applied at various muscles and has a long track record of clinical utility. Kinemyography is valid to monitor recovery of neuromuscular transmission at the adductor pollicis muscle (AP), whereas phonomyography is easy to apply to various muscles and shows promising agreement with MMG. Monitoring of the corrugator supercilii muscle (CS) may be used to determine the earliest time for tracheal intubation as it reflects laryngeal relaxation better than monitoring at the AP. Recovery of neuromuscular transmission is best monitored at the AP, since it is the last muscle to recover from neuromuscular blockade (NMB). If train-of-four (TOF) stimulation is used, a TOF-ratio > 0.9 should be the target before awakening the patient. If surgery or the type of anesthesia necessitates NMB of a certain degree, e.g., TOF-ratio = 0.25, monitoring of muscles which best reflect the degree of NMB at the surgical site is preferable. CONCLUSION: Objective methods should be used to monitor neuromuscular function in clinical anesthesia. Acceleromyography offers the best compromise with respect to ease of use, practicality, versatility, precision and applicability at various muscles. The CS is the optimal muscle to determine the earliest time for intubation, e.g., for rapid sequence induction.     

Effects of an Intubating Dose of Succinylcholine and Rocuronium on the Larynx and Diaphragm: An Electromyographic Study in Humans

Background: Paralysis of the vocal cords is one objective of using relaxants to facilitate tracheal intubation. This study compares the neuromuscular blocking effect of succinylcholine and rocuronium on the larynx, the diaphragm, and the adductor pollicis muscle.

Methods: Electromyographic response was used to compare the neuromuscular blocking effect of succinylcholine and rocuronium on the laryngeal adductor muscles, the diaphragm, and the adductor pollicis muscle. Sixteen patients undergoing elective surgery were anesthetized with propofol and fentanyl, and their tracheas were intubated without neuromuscular blocking agents. The recurrent laryngeal and phrenic nerves were stimulated at the neck. The electromyographic response was recorded from electrodes placed on the endotracheal tube and intercostally before and after administration of 1 mg/kg succinylcholine or 0.6 mg/kg rocuronium.

Results: The maximum effect was greater at the adductor pollicis (100 and 99%) than at the larynx (96 and 97%) and the diaphragm (94 and 96%) after administration of succinylcholine and rocuronium, respectively (P 相似文献   

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.     

Assessment of neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles

Purpose  

We studied neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles in anesthetized patients.     

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     

Neuromuscular monitoring at the orbicularis oculi may overestimate the blockade in myasthenic patients

BACKGROUND: In most publications about myasthenia, monitoring neuromuscular blockade during anesthesia is recommended. In healthy patients, the relation of blockade between muscles has been established, but there is little information about the relation in myasthenic patients. Our objective was to investigate whether the relation between the orbicularis oculi and adductor pollicis muscles is the same in healthy patients and myasthenic patients. METHODS: After anesthesia was induced with 4-6 mg/kg thiopental and 2 microg/kg fentanyl, followed by 2% sevoflurane and 60% nitrous oxide in oxygen, 10 healthy patients and 10 myasthenic patients received 0. 025 and 0.01 mg/kg vecuronium, respectively. Neuromuscular monitoring was performed with use of accelerometry at the orbicularis oculi and the adductor pollicis muscles by stimulating the temporal branch of the facial nerve and the ulnar nerve. RESULTS: The relation of blockade between these two muscles was not the same in healthy patients and myasthenic patients: in healthy patients, the maximum neuromuscular blockade with 0.025 mg/kg vecuronium was less in the orbicularis oculi than in the adductor pollicis (median 72% vs. 91%; P < 0.05); in contrast, in myasthenic patients, the blockade with 0.01 mg/kg vecuronium was greater in the orbicularis oculi than in the adductor pollicis (median 96% vs. 62%; P < 0.05). CONCLUSION: Neuromuscular monitoring at the orbicularis oculi may overestimate blockade in myasthenic patients. Extubation must be performed when the muscle most sensitive to neuromuscular blocking agents is recovered. Therefore, neuromuscular monitoring at the orbicularis oculi is recommended to avoid persistent neuromuscular blockade in patients with myasthenia gravis.     

Neuromuscular effects of rapacuronium on the diaphragm and skeletal muscles in anaesthetized patients using cervical magnetic stimulation for stimulating the phrenic nerves

BACKGROUND AND OBJECTIVE: Non-depolarizing neuromuscular blocking agents have a shorter duration of action on the diaphragm than on skeletal muscles. It was to be tested if this also held true for rapacuronium, a short-acting, amidosteroid non-depolarizing neuromuscular blocker, lately withdrawn from the market, using a novel technique for stimulating the diaphragm and assessing its function. METHODS: Anaesthesia was induced with propofol 2 mg kg(-1) and remifentanil 1 microg kg(-1), and the trachea was intubated after topical anaesthesia. Rapacuronium was given at a dose of 1.5 mg kg(-1). The diaphragm was stimulated by cervical magnetic stimulation of the phrenic nerves (2 Tesla, single coil) and airway pressure responses were measured at the endotracheal tube connector. The neuromuscular effects at the adductor pollicis and orbicularis oculi muscles were measured by acceleromyography. RESULTS: Fifteen males and five females (ASA I and II; 27 +/- 8 yr; 73 +/- 13kg; mean +/- SD) were recruited. Median maximal relaxation was less (P < 0.01) for the diaphragm (89%) than for the adductor pollicis or orbicularis oculi muscles (each 100%). The time to 25% recovery was shorter for the diaphragm than for adductor pollicis or orbicularis oculi (7.5 +/- 3.1 versus 14.1 +/- 3.7 and 15.1 +/- 3.5 min, respectively, P < 0.01). Recovery from 25 to 75% was identical for the diaphragm and adductor pollicis (9.4 +/- 2.9 versus 9.1 +/- 3.5 min), but longer for orbicularis oculi (13.4 +/- 4.2 min, P < 0.01). The median recovery time to TOF0.8 was shorter for the diaphragm (23.9 min) than for the adductor pollicis or orbicularis oculi muscles (31.5 and 28.4 min, respectively; P < 0.05). CONCLUSIONS: As with other non-depolarizing muscle relaxants, the duration of the clinical effect of rapacuronium was shorter for the diaphragm than for skeletal muscle. The recovery index was identical for the diaphragm and adductor pollicis.     

Duration of Anesthesia before Muscle Relaxant Injection Influences Level of Paralysis

Background: Dosage guidelines for muscle relaxants are based on dose-response studies, normally performed after several minutes of stable nitrous oxide (N2O)-opioid anesthesia. However, relaxants are used immediately after induction of anesthesia. The study was designed to determine the influence of the duration of anesthesia and N2O on the onset time at the adductor pollicis (AP) and the corrugator supercilii (CS) muscles of maximum neuromuscular blockade after mivacurium.

Methods: After institutional approval and informed consent, patients were randomly allocated into three groups. Anesthesia was induced with alfentanil and propofol. Group A (n = 10) received mivacurium (0.1 mg/kg) immediately after loss of consciousness. Groups B (n = 10) and C (n = 10) received mivacurium after 15 min of anesthesia with propofol alone (B) or propofol with N2O (C). The evoked response to train-of-four stimulation was measured by acceleromyography at the AP and the CS.

Results: Maximum neuromuscular blockade (%T1, median [range]) was significantly less in group A than in groups B and C (P < 0.001) at both the AP (81 [47-90]; 90 [35-100]; 100 [93-100], respectively) and the CS (19 [5-63]; 68 [61-100]; 89 [72-100], respectively). Maximum neuromuscular blockade was less in group B than in group C (P < 0.001) at the AP. Onset time of maximum neuromuscular blockade was not different between groups but was shorter at the CS than at the AP.     

Duration of anesthesia before muscle relaxant injection influences level of paralysis

BACKGROUND: Dosage guidelines for muscle relaxants are based on dose-response studies, normally performed after several minutes of stable nitrous oxide (N O)-opioid anesthesia. However, relaxants are used immediately after induction of anesthesia. The study was designed to determine the influence of the duration of anesthesia and N O on the onset time at the adductor pollicis (AP) and the corrugator supercilii (CS) muscles of maximum neuromuscular blockade after mivacurium. METHODS: After institutional approval and informed consent, patients were randomly allocated into three groups. Anesthesia was induced with alfentanil and propofol. Group A (n = 10) received mivacurium (0.1 mg/kg) immediately after loss of consciousness. Groups B (n = 10) and C (n = 10) received mivacurium after 15 min of anesthesia with propofol alone (B) or propofol with N O (C). The evoked response to train-of-four stimulation was measured by acceleromyography at the AP and the CS. RESULTS: Maximum neuromuscular blockade (%T1, median [range]) was significantly less in group A than in groups B and C ( < 0.001) at both the AP (81 [47-90]; 90 [35-100]; 100 [93-100], respectively) and the CS (19 [5-63]; 68 [61-100]; 89 [72-100], respectively). Maximum neuromuscular blockade was less in group B than in group C ( < 0.001) at the AP. Onset time of maximum neuromuscular blockade was not different between groups but was shorter at the CS than at the AP. CONCLUSIONS: Duration of anesthesia and N O before mivacurium injection affect intensity of neuromuscular blockade but not onset time. Neuromuscular blockade obtained at the AP after several minutes of stable anesthesia with N O is greater than immediately after induction. This explains in part the discrepancy between the measured ED and the intubating dose.     

Potency of succinylcholine at the diaphragm and at the adductor pollicis muscle

To quantify the differential effect of succinylcholine at the diaphragm and the adductor pollicis muscle, 10 patients were studied during halothane-nitrous oxide anesthesia. Train-of-four stimulation was applied to the ulnar and phrenic nerves. The force of contraction and the electromyographic response of the adductor pollicis were measured and compared with the diaphragmatic electromyogram. Then dose-response curves for both muscles were constructed using incremental doses of succinylcholine with an infusion to replace metabolized or redistributing drug. Linear regressions were obtained between the logit transformation of neuromuscular blockade at the adductor pollicis and diaphragm and the logarithm of the dose. The diaphragm was relatively resistant to succinylcholine. At 90% adductor pollicis block, the diaphragm was only (mean +/- SEM) 37 +/- 3% blocked. The diaphragm required 1.8 +/- 0.2 times as much succinylcholine as the adductor pollicis for an identical 90% block. The ED50 and ED90 values for succinylcholine at the diaphragm were 0.23 +/- 0.04 and 0.40 +/- 0.09 mg/kg, respectively. Corresponding values for the adductor pollicis were 0.14 +/- 0.01 and 0.21 +/- 0.02 mg/kg. The data indicate that the degree of adductor pollicis blockade might overestimate the intensity of diaphragmatic paralysis.     

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.      

Effects of mivacurium on the diaphragm evaluated by cervical magnetic stimulation of the phrenic nerves

BACKGROUND AND OBJECTIVE: Non-depolarizing neuromuscular blocking agents have differential effects on the diaphragm and skeletal muscles. We employed a new method to study the effects of mivacurium on the diaphragm and compared the results obtained with this method with published data. METHODS: Anaesthesia was induced and maintained with propofol and alfentanil and the trachea was intubated after topical anaesthesia. Contractions of the diaphragm were induced by cervical magnetic stimulation of the phrenic nerves and quantified by measuring airway pressure responses. The neuromuscular effects on skeletal muscles were measured by acceleromyography of the adductor pollicis muscle. Mivacurium (0.15 mg kg(-1)) was injected and neuromuscular responses were recorded until the effects had waned. RESULTS: Eleven male and 10 female patients (ASA I-II; 57 +/- 16 yr; 78 +/- 13 kg; mean +/- standard deviation) participated. Median maximal reduction of twitch response was less (P < 0.05) for the diaphragm (89%) than for the adductor pollicis (100%). Time to 25% recovery was shorter for the diaphragm than for the adductor pollicis (8.8 +/- 2.2 min vs. 22.6 +/- 5.0 min, P < 0.05). The difference between the recovery index of the diaphragm (7.3 min (3.6-18.4)) and the adductor pollicis (8.2 min (4.4-20.9) (median (range)) just missed our chosen level of statistical significance (P = 0.06). The recovery time to train-of-four 0.8 was shorter for the diaphragm (median and 95% confidence interval 25.1 +/- 10.2 min) than for the adductor pollicis (median and 95% confidence interval 37.5 +/- 9.4 min, P < 0.05). CONCLUSIONS: The duration of the clinical effect of mivacurium on the diaphragm is markedly shorter than on the adductor pollicis muscles but there was only a small difference in the recovery index of the two muscles. These effects and the time courses determined with the new method closely resemble the results obtained with different methods in other studies.     

Dominance of the hand does not change the phonomyographic measurement of neuromuscular block at the adductor pollicis muscle

Phonomyography (PMG) is a novel method to determine neuromuscular blockade (NMB) with high sensitivity and applicability at all muscles. The adductor pollicis muscle has long been used in research and clinical practice as reference for neuromuscular monitoring. The goal of our study was to compare PMG signals (train-of-four [TOF] ratios and T(1)/T(0) values) from both hands of the same patient to investigate the influence of hand dominance on neuromuscular monitoring. In 14 patients, PMG was recorded via small piezoelectric microphones taped over the thenar mass of both hands. After induction of anesthesia, both ulnar nerves were stimulated supramaximally using TOF stimulation every 12 s. Mivacurium 0.2 mg/kg was administered within 5 s. Onset, maximum effect, and offset of NMB were compared between both adductor pollicis muscles. Twelve patients were right-handed and two patients were left-handed. No statistical difference was found between the signals from the dominant or nondominant hand. Correlation was very good (r = 0.95). Agreement was excellent with a bias of -0.57% and limits of agreement of -17.9% to 16.7% (dominant - nondominant hand). This study shows minimal bias, good correlation and no statistical difference when NMB is monitored at both the dominant and nondominant adductor pollicis muscles. Both hands could be used interchangeably to assess NMB at the adductor pollicis muscle.     

The neuromuscular blocking effect of vecuronium on the human diaphragm

This study compares the neuromuscular blocking effect of vecuronium (0.1 mg/kg) on the diaphragm and the adductor pollicis in nine anesthetized patients. Monitoring of the diaphragm consisted of measurement of the transdiaphragmatic pressure after bilateral phrenic nerve stimulation. Onset time for neuromuscular blockade of the diaphragm was 1.6 +/- 0.3 min (+/-SD) compared to 2.5 +/- 0.3 min in the adductor pollicis (P less than 0.001). The diaphragm recovered earlier and more rapidly than the adductor pollicis. The twitch height (TH) returned to 25% of its control value after 27 +/- 8 min for the diaphragm, compared to 41 +/- 11 min for the adductor pollicis (P less than 0.01). Complete TH recovery was achieved after 49 +/- 14 min for the diaphragm and after 74 +/- 22 min for the adductor pollicis (P less than 0.01). The recovery index of 12 +/- 4 min for the diaphragm was significantly shorter (P less than 0.05) than for the adductor pollicis (20 +/- 9 min.) We conclude that monitoring of peripheral muscles in anesthetized patients given vecuronium provides adequate information about the degree of paralysis of the diaphragm.     

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)