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At least 415 records · Page 23Linked to original sources
PubMed2003

Surface electromyography and mechanomyography recording: a new differential composite probe.

The objective of the study was to develop a new surface probe for differential mechanomyographic (MMG) and electromyographic (EMG) recording. Differential amplification is commonly used in electromyography to improve the signal-to-noise ratio. A new composite probe was developed with two electrodes (EMG) and two identical piezo-electric membranes (MMG) to be positioned on muscle. The probe had two built-in fixed-gain differential amplifiers: one to amplify the electric signal and the other to amplify the vibration signal. A similar non-differential MMG probe was used for comparisons. Burst muscular activity was recorded using the non-differential and differential probes and was used to test the performance of the two probes in suppressing artifacts of non-muscular origin. Power spectrum analysis of signals from the two probes showed that differential amplification significantly improved the signal-to-noise ratio in MMG recordings and significantly suppressed artifacts (power difference > 90%). The composite probe allowed simultaneous differential recording of MMG and EMG signals from the same muscular site. It recorded muscular activity more efficiently than the non-differential probe and could therefore be useful in studying fatigue and neuromuscular diseases.

Artifacts↗
PubMed2004

Effect of accelerometer location on mechanomyogram variables during voluntary, constant-force contractions in three human muscles.

To understand better the features of the mechanomyogram (MMG) with different force levels and muscle architectures, the MMG signals detected at many points along three muscles were analysed by the application of a linear array of MMG sensors (up to eight) over the skin. MMG signals were recorded from the biceps brachii, tibialis anterior and upper trapezius muscles of the dominant side of ten healthy male subjects. The accelerometers were aligned along the direction of the muscle fibres. One accelerometer was located over the distal muscle innervation zone, and the other six or seven accelerometers were placed over the muscle, forming an array of sensors with fixed distances between them. The array covered almost the entire muscle length in all cases. MMG signals detected from adjacent accelerometers had similar shapes, with correlation coefficients ranging from about 0.5 to about 0.9. MMG amplitude and characteristic spectral frequencies significantly depended on accelerometer location. The MMG amplitude was maximum at the muscle belly for the biceps brachii and the tibialis anterior. Higher MMG characteristic spectral frequencies were associated with higher amplitudes in the case of the biceps brachii, whereas the opposite was observed for the tibialis anterior muscle. In the upper trapezius, the relationship between characteristic spectral frequencies, MMG amplitude and contraction force depended on the accelerometer location. This suggested that MMG spectral features do not only reflect the mechanical properties of the recruited muscle fibres but depend on muscle architecture and motor unit territorial distribution. It was concluded that the location of the accelerometer can have an influence on both amplitude and spectral MMG features, and this dependence should be considered when MMG signals are used for muscle assessment.

Acceleration↗
PubMed1998

Technical aspects of mechnomyography recording with piezoelectric contact sensor.

The piezoelectric contact sensor has been widely utilised in mechanomyography (MMG). The authors aim to clarify the mechanical variables (i.e. acceleration, velocity or displacement) reflected by the MMG signal detected with a piezoelectric contact sensor (PEC), and compare the results with those obtained simultaneously by an accelerometer (ACC). To measure the acceleration-frequency response, a mechanical sinusoidal excitation of 5 to 300 Hz at a constant magnitude of 0.01 G was applied to the two transducers. The acceleration-frequency response of the ACC transducer was confirmed to be almost flat. The PEC without any restriction of the transducer housing (including the combined seismic mass) demonstrated a similar response to the ACC transducer. The PEC transducer output with restricted housing decreased with increasing sinusoidal frequency and an attenuation slope of -40 dB/decade and phase angle of -180 degrees. The voluntary MMG signal during isometric knee extension was recorded simultaneously with the two transducers. The amplitude spectral density distribution of the MMG from the PEC transducer was narrow and the mean frequency was approximately one-half that obtained from the ACC transducer. The amplitude spectral density distribution with the PEC transducer resembled that of the double integral over time of the ACC transducer signal. The phase angle of the PEC transducer signal was different from that of the ACC transducer signal by approximately -180 degrees. These results suggest that the PEC transducer acts as a displacement meter of muscle vibration. In addition, differences in the MMG frequency components relating to the transducer type must be taken into consideration when investigating the mechanical activity of muscle.

Humans↗
PubMed1997

Dynamometer for rat plantar flexor muscles in vivo.

A dynamometer is designed and fabricated to measure the force output during static and dynamic muscle actions of the plantar flexor muscles of anaesthetised rats in vivo. The design is based on a computer-controlled DC servomotor capable of angular velocities in excess of 17.5 rad s-1. The system controls the range of motion, angular velocity and electrical stimulation of the muscles, while monitoring the force output at the plantar surface of the foot. The force output is measured by a piezo-electric load cell that is rated at 5 kg capacity. Angular velocity and position are measured by a DC tachometer and potentiometer, respectively. All measurement devices are linear (r2 = 0.9998). The design minimises inertial loading during high-speed angular motions, with a variation in force output of less than 0.2%. The dynamometer proves to be an accurate and reliable system for quantifying static and dynamic forces of rat plantar flexor muscles in vivo.

Animals↗
PubMed1986

Anorectal continence and bladder function. Effects of major sacral resection.

The effect of sacral resection up to S-2 has been investigated in two patients with "chordomas," surgical division of the spinal roots was unilateral and bilateral, respectively. Anal manometry, electromyography of the sphincters, and the ascertaining of tactile, thermic, and painful stimuli perception in the perineum and anal canal were executed to determine the effects of denervation on anorectal continence. Vesical function was tested by vesical manometry. Results differ strongly between the two patients: the first, with unilateral loss of S-2, has perfect anorectal continence. The second, with bilateral loss of S-2, is incontinent and unable to discriminate rectal contents. It is sufficient to retain only one S-2 root for the maintenance of physiologic continence, including distinction between different types of bowel contents (gaseous or solid) passing through the anal canal. The same is true concerning bladder function.

Anal Canal↗
PubMed1990

Clinical, electrical and mechanical correlations during recovery from neuromuscular blockade with vecuronium.

In order to determine correlations between electromyographic (EMG), mecanomyographic (MMG) and clinical criteria of adequate recovery from neuromuscular blockade with vecuronium, seven young healthy conscious volunteers were given subparalysing doses of vecuronium. During recovery from neuromuscular blockade, vital capacity, negative inspiratory pressure, peak expiratory flow rate and five-second head lift were assessed. Neuromuscular monitoring included the evoked EMG response of the adductor digiti minimi and the simultaneous evoked MMG response of the adductor pollicis on the same side. We found that all subjects maintained head lift for five seconds at EMG T4T1 of 0.70, and they achieved normal respiratory tests at EMG T4/T1 of 0.90. The MMG T4/T1 needed for the subjects to perform normal respiratory tests was found to be 0.50, at which time six of the seven subjects were able to perform adequately the head lift test.

Adult↗
PubMed1986

Rapid tracheal intubation with atracurium--a comparison of priming intervals.

To determine the optimal interval between the administration of the priming dose and the intubating dose, atracurium was given to 44 patients either in a single dose of 0.5 mg X kg-1 or in an initial dose of 0.06 mg X kg-1 followed two, three or five minutes later with 0.44 mg X kg-1. When atracurium was given as a single bolus of 0.5 mg X kg-1 the time to 100 per cent twitch suppression (onset time) was 90.9 +/- 36 (mean +/- SD) seconds. When the priming interval was two minutes, the onset time of the intubating dose was 76.6 +/- 42.2 seconds (p = NS). But when the priming interval was three or five minutes, the onset times were 42.2 +/- 16.5 (p less than 0.01) and 52.6 +/- 28.8 (p less than 0.05) seconds respectively. Waiting for five minutes after the administration of the priming dose did not improve the intubating conditions. It is concluded that three minutes appears to be the optimal time interval for the administration of atracurium in divided doses. When a priming dose of atracurium is given three minutes before the intubating dose, it can provide an alternative to succinylcholine for rapid endotracheal intubation.

Adolescent↗
PubMed1996

Acceleromyography improves detection of residual neuromuscular blockade in children.

PURPOSE: To determine whether detection of residual blockade is improved by using the accelerograph. A secondary objective was to compare acceleromyographic measurements with those obtained by electromyography. METHODS: In a prospective, randomized, double-blind investigation, 22 anaesthetized children were studied during recovery from neuromuscular blockade following 0.1 mg.kg-1 vecuronium i.v.. Assessments of depth of block began 10 min after injection and were repeated at one minute intervals using electromyography (Datex, Relaxograph) in one hand, and acceleromyography (Biometer, Tofguard) in the other, to measure response of the adductor pollicis to train-of-four (TOF) stimulation of the ulnar nerve. Monitoring was stopped when no fade was visible and TOF ratio > or = 0.7. The electromyographic (EMG) and acceleromyographic (AMG) data were compared with corresponding observations of the number of twitches and TOF fade in the visible responses of the thumb, made by the attending anaesthetist. The method of Bland and Altman was used to compare differences between AMG and EMG data. RESULTS: During recovery from neuromuscular blockade, fade was no longer visible clinically 38.6 +/- 10.4 min (mean +/- SD) after the administration of vecuronium. This corresponded to TOF ratios of 0.04 +/- 0.23 by AMG and 0.34 +/- 0.21 by EMG. Usually, two twitches were visible before AMG detected the first twitch. The time to TOF ratio > or = 0.7 by AMG and EMG was similar at 49.1 +/- 10.5 and 50.9 +/- 9.0 min, respectively. The bias between AMG and EMG was one minute, with limits of agreement from -10 to nine min. CONCLUSION: AMG is superior to visual assessment in detecting residual neuromuscular block and provides similar estimates of recovering block as the more cumbersome EMG.

Anesthesia Recovery Period↗
PubMed1997

Onset of vecuronium neuromuscular blockade at the hand with an arterio-venous shunt.

PURPOSE: To evaluate the onset of vecuronium neuromuscular blockade in the hand with an arterio-venous shunt for haemodialysis. METHODS: In 15 adult patients receiving haemodialysis for renal failure the onset of vecuronium-induced neuromuscular blockade after 0.08 mg-kg-1 vecuronium i.v. was measured. Using train-of-four mechanomyographic monitoring, the force of contraction of the adductor pollicis of both hands with and without arterio-venous shunt was measured simultaneously. RESULTS: The times from the injection to the first depression of twitch response (latent onset) and 95% twitch depression (onset) in the hand with and without arterio-venous shunt were 114.7 +/- 33.4 and 218.7 +/- 59.9 and 117.3 +/- 34.3 and 208.7 +/- 60.9 sec respectively. No difference in the onset of vecuronium neuromuscular blockade in the hand an arterio-venous shunt was demonstrated. CONCLUSION: The presence of an arteriovenous fistula does not modify the onset on neuromuscular blockade. Either arm can be used to monitor onset of neuromuscular blockade in chronic renal failure patients with an arterio-venous shunt in the hand for haemodialysis.

Adult↗
PubMed1999

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.

Adolescent↗
PubMed2002

Duration of control stimulation does not affect onset and offset of neuromuscular blockade at the corrugator supercilii muscle measured with phonomyography or acceleromyography.

PURPOSE: Phonomyography (PMG) is a novel technique for measuring neuromuscular blockade (NMB). The effect of the duration of control stimulation on the onset and duration of blockade was investigated using PMG and acceleromyography (AMG). METHODS: After induction of anesthesia, a microphone was placed above the middle portion of the left eyebrow, and an acceleromyographic probe was placed above the middle portion of the right eyebrow. Twenty patients were randomized to receive bilateral, single-twitch, facial nerve stimulation (0.1 Hz, 20 mA) with three minutes (n = 10) or ten minutes (n = 10) of supramaximal stimulation before mivacurium 0.2 mg.kg(-1) was administered. Onset, maximum effect, and offset of NMB were measured. RESULTS: Using PMG, lag time, onset time, maximum effect, and time to reach 75% of control twitch height (mean +/- SD) were 36 +/- 27 sec, 136 +/- 35 sec, 89 +/- 10%, and 12.1 +/- 4.5 min, respectively, after three minutes of control stimulation and were 40 +/- 22 sec, 122 +/- 40 sec, 93 +/- 3%, and 12.4 +/- 4.9 min, after ten minutes. Using AMG, the values were 38 +/- 23 sec, 106 +/- 28 sec, 79 +/- 6%, and 14.3 +/- 5.9 min, respectively, after three minutes and were 34 +/- 22 sec, 106 +/- 28 sec, 76 +/- 10%, and 14.9 +/- 3.7 min, after ten minutes. Compared to PMG, AMG revealed significant bias for onset time (-30 sec), maximum effect (-16%) and time to reach 75% of control twitch height (1.5 min), with wide limits of agreement of 66 sec, 22%, and 5.6 min, respectively. CONCLUSION: The duration of control stimulation did not influence the time course of blockade measured by either method. Three minutes of supramaximal stimulation is sufficient to measure pharmacodynamic parameters. AMG measures a shorter onset and longer recovery time and reduced anesthesiology the maximum effect compared to PMG.

Adult↗
PubMed2004

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

PURPOSE: Phonomyography consists of recording low frequency sounds created during muscle contraction. In this study, phonomyography of three regions of the hand was compared to mechanomyography of the adductor pollicis. METHODS: In 12 patients, phonomyography was recorded via small condenser microphones taped over the thenar mass, the hypothenar eminence, and the dorsal groove between the first and second metacarpal bones to record the acoustic signals of adductor pollicis and the hypothenar and first dorsal interosseus muscles, respectively. Mechanomyography of the adductor pollicis was recorded simultaneously using a force transducer. After induction of anesthesia, the ulnar nerve was stimulated supramaximally using train-of-four (TOF) stimulation every 12 sec. Onset, maximum effect, and offset of neuromuscular block after rocuronium 0.6 mg x kg(-1) were measured using phonomyography and compared to mechanomyography using ANOVA and the Bland-Altman test. RESULTS: Phonomyographic measurements of onset and maximum effect of neuromuscular blockade were not significantly different from mechanomyographic measurements. Phonomyographic measurements of offset (T25%, T75 %, TOF 0.8) of neuromuscular block at the thenar muscles and first dorsal interosseus muscles were not significantly different from mechanomyographic measurements at adductor pollicis; however, T50%, T75% and T90% phonomyographic measurements at the hypothenar muscle were significantly shorter than at any other muscle site. CONCLUSION: There was good agreement between mechanomyographic measurements at the adductor pollicis muscle and phonomyographic measurements at the thenar and the first dorsal interosseus muscles. Phonomyography of those two muscles could be used interchangeably with mechanomyography of adductor pollicis for clinical purposes.

Analysis of Variance↗
PubMed2004

Comparison of phonomyography with balloon pressure mechanomyography to measure contractile force at the corrugator supercilii muscle.

PURPOSE: Phonomyography is based on the creation of low frequency sounds during muscle contraction, which can be recorded and used for neuromuscular monitoring. In this study, balloon pressure mechanomyography, a novel method to measure the force of contraction via pressure changes in an air-filled balloon, was compared with phonomyography to determine neuromuscular blockade at the corrugator supercilii muscle. METHOD: After approval of the Ethics Committee and informed consent, 15 patients were studied. A small condenser microphone was taped to the area just above the eyebrow for phonomyography; an air-filled balloon was taped to the area just above the opposite eyebrow. After induction of anesthesia using remifentanil and propofol, a laryngeal mask airway was inserted without the aid of neuromuscular blocking agents. The facial nerve was stimulated supramaximally with single-twitch stimulation (0.1 Hz) using superficial electrodes placed on both temporal areas for onset and train-of-four stimulation every 12 sec during offset of neuromuscular blockade produced by mivacurium 0.1 mg.kg(-1). Onset and recovery measured by the two methods were compared using the t test and agreement between phonomyography and balloon pressure mechanomyography was examined using the Bland-Altman method. RESULTS: Onset, peak effect, and time to reach 25%, 75%, and 90% of control twitch response for phonomyography vs balloon pressure method were 83 +/- 16 sec vs 81 +/- 15 sec, 80 +/- 15% vs 82 +/- 17%, 7.7 +/- 2.3 min vs 7.5 +/- 2.4 min, 9.9 +/- 4.1 min vs 10.5 +/- 4 min, and 12.6 +/- 4.3 min vs 13.1 +/- 4.5 min respectively without being significantly different. Mean bias was 1% with limits of agreement of -9 and +9% of twitch height (T1). CONCLUSION: We applied a balloon pressure method to measure the force at the corrugator supercilii. Phonomyography at the corrugator supercilii shows good agreement with this modified version of mechanomyography.

Adult↗
PubMed2005

Monitoring neuromuscular blockade at the vastus medialis muscle using phonomyography.

PURPOSE: The vastus medialis muscle has been recently proposed as a new site for monitoring neuromuscular blockade (NMB). The purpose of this study is to compare NMB at the vastus medialis with the adductor pollicis muscle using phonomyography (PMG). METHODS: Fifteen patients were enrolled in the study. Anesthesia was induced with remifentanil 0.25 to 0.5 microg x kg(-1) x min(-1), followed by propofol 2 to 2.5 mg(-1) x kg(-1) iv. Analgesia was provided by remifentanil 0.05 to 0.25 microg x kg (-1) x min(-1) iv throughout surgery. A small piezo-electric microphone was attached to the middle of the thenar mass of the right hand to record acoustic signals produced by the contraction of the adductor pollicis muscle. A second microphone was fixed to the medial part of the thigh, 10 cm over the patella, to record the response from the vastus medialis muscle. The ulnar nerve and the im branches of the femoral nerve were stimulated using train-of-four stimulation every 12 sec. Onset, maximum effect, and offset of neuromuscular block were measured after mivacurium 0.2 mg x kg(-1) iv and compared. RESULTS: At the vastus medialis muscle, the onset of NMB was significantly shorter at 1.9 +/- 0.6 min vs 2.8 +/- 0.7 min, the maximum effect less pronounced at 85 +/- 11% vs 96 +/- 2% and recovery of NMB to 25%, 75%, 90% of twitch control height more rapid than at the adductor pollicis muscle at 17 +/- 2.2 min vs 21.6 +/- 4.2 min, 26.7 +/- 6.5 vs 21 +/- 4.1 min and 30.7 +/- 6.6 vs 35.9 +/- 7.1 min, respectively. CONCLUSIONS: PMG can be used to measure NMB at the vastus medialis muscle. We found a shorter onset time, less pronounced maximum effect and more rapid recovery of NMB at the vastus medialis muscle than at the adductor pollicis muscle.

Adult↗