Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MYOGRAPHY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
PubMed2006

Comparison of phonomyography, kinemyography and mechanomyography for neuromuscular monitoring.

PURPOSE: The gold standard of neuromuscular monitoring is mechanomyography (MMG). Phonomyography (PMG) and kinemyography (KMG) are new methods of neuromuscular monitoring. In this study, all three methods were compared to determine neuromuscular blockade at the adductor pollicis muscle. METHODS: In 14 patients, phonomyography was recorded via a microphone taped to the thenar region. A standard mechanomyographic device was applied to the same thumb, and attached to the force transducer. On the contralateral side, a NMT-Mechanosensor(R) probe was attached to the thumb and forefinger (KMG). After induction of general anaesthesia, the ulnar nerves were stimulated supramaximally using superficial electrodes at the wrists using train-of-four (TOF) stimulation every 12 sec. Onset and recovery indices measured by the three methods after mivacurium 0.2 mg x kg(-1) iv were compared using ANOVA-multiple group comparisons. Agreement between methods was determined using Lin's concordance correlation coefficient. RESULTS: Onset time and peak effect measured via MMG and PMG were similar. Recovery times from neuromuscular blockade (NMB) as measured via the three methods were not different. Agreement between PMG and MMG was excellent for onset and offset of NMB but unsatisfactory for peak effect. Agreement between MMG and KMG was satisfactory for TOF 0.25 and 0.50, and excellent for TOF 0.75 and 0.90 (onset and peak effect not determined for KMG). Agreement between PMG and KMG was satisfactory for TOF 0.25, 0.50 and 0.75, and excellent for TOF 0.90. CONCLUSION: Mechanomyography, PMG and KMG show satisfactory agreement for determination of recovery of NMB for clinical purposes.

Adult↗
PubMed2006

Mivacurium-induced neuromuscular block in adult patients suffering from Charcot-Marie-Tooth disease.

PURPOSE: The response to non-depolarizing neuromuscular blocking drugs is variable in patients with Charcot-Marie-Tooth (CMT) disease. We speculated that CMT involvement of the monitored muscle may be partially responsible for this inconsistency. We therefore investigated the response to a standard dose of mivacurium simultaneously assessed at adductor pollicis (AP) and orbicularis oculi (OO) muscles in five patients with CMT. CLINICAL FEATURES: Over a period of one year, five adult patients with CMT scheduled for orthopedic surgery were studied. The right arm and the right supercilliary arch were prepared for acceleromyographic (AMG) neuromuscular monitoring. The AMG probes were attached at the distal interphalangeal joint of the right thumb and on the right upper eyelid to record the response of the AP and OO, respectively. The ulnar nerve and upper part of the facial nerve were stimulated supramaximally with repeated train-of-four stimuli (2 Hz, 0.2 msec) every 15 sec via applied surface electrodes. Following monitor calibration and induction of general anesthesia, mivacurium 0.2 mg x kg(- 1) iv was given, and the time course of relaxation and recovery were assessed. Times to spontaneous recovery of T1 to 25% were 15 +/- 3 vs 12 +/- 4 min in the AP and OO muscle groups respectively, whereas times to 90% recovery were 23 +/- 5 vs 29 +/- 10 min, respectively. CONCLUSION: The onset and recovery characteristics associated with mivacurium-induced neuromuscular block were similar at the AP and OO muscle groups. A near normal response to mivacurium was observed in this small series of patients with CMT disease.

Adult↗
PubMed2000

[The effect of different priming doses on the pharmacodynamics of cisatracurium].

OBJECTIVE: The aim of the study was to evaluate the effect of two different priming regimen on the onset time of 100 micrograms/kg cisatracurium, when compared to bolus administration. METHODS: 51 patients were randomly assigned and received either a bolus of 100 micrograms/kg cisatracurium, or a priming dose of 10 micrograms/kg cisatracurium followed after 4 min by 90 micrograms/kg cisatracurium, or a priming dose of 15 micrograms/kg cisatracurium followed after 4 min by 85 micrograms/kg cisatracurium. The neuromuscular monitoring was performed using a mechanomyograph (Groningen II Monitor). Anaesthesia was induced with propofol and fentanyl and maintained by continuous infusion of propofol. RESULTS: The priming combination of 15 micrograms/kg cisatracurium followed after 4 min by 85 micrograms/kg cisatracurium produced a statistically significant reduction in the onset time (95% block) (180 +/- 60 s) and time to complete block (210 +/- 48 s), when compared to the bolus group (240 +/- 60 s and 288 +/- 66 s) (p < 0.05). CONCLUSION: Our data indicate that the "priming principle" is an appropriate technique to shorten the onset time of cisatracurium. To achieve a maximum effect the priming combination of 15 micrograms/kg cisatracurium followed after 4 min by 85 micrograms/kg cisatracurium is recommended.

Adult↗
PubMed1999

[Accuracy and dose dependency of the train-of-four count].

UNLABELLED: The estimation of a nondepolarizing neuromuscular block using the train-of-four (TOF) count shows wide differences compared to the mechanomyographic measurement. The purpose of this study was to evaluate the clinical significance of these differences. METHODS: 89 patients (ASA I-II) in 6 groups received general anesthesia with fentanyl, propofol and a single dose atracurium (150, 200, 250, 300, 450 and 600 microg/kg). Neuromuscular transmission was monitored by stimulation of the ulnar nerve at the wrist with supramaximal TOF stimuli repeated every 15 s using a peripheral nerve stimulator. The isometric force contraction of the m. adductor pollicis was recorded. The height of T1 at reappearance of the second (T2) and fourth (T4) twitch was noted. Also noted was the time difference between the first reappearance of T4 and the 25% recovery of T1. Statistical significance of the results was calculated by the h-test of Kruskal and Wallis. Testing the reliability of the TOF count, a 95% interval of confidence was calculated RESULTS: There were no significant differences between the mean ages, heights and weights of the six groups. T2 and T4 re-appeared at 11+/-2% and 24+/-6% recovery of T1, respectively. Again, there were no significant differences between the six dose groups (Fig. 1). The time difference between the re-appearance of T4 and the 25% recovery was -1.0+/-2 (range: -5-3) minutes. The calculation of a 95% interval of confidence indicated a recovery between 14% and 33% at reappearance of T4, 25% recovery can be expected 5 min before to 3 min after reappearance of T4, respectively. CONCLUSIONS: At reappearance of T4, a recovery of neuromuscular block of 25% is missed only by 3 to 5 min during relaxation with atracurium. We consider this margin of error as unimportant for clinical use. More-over we were able to show that the TOF-count is not dose dependent.

Adult↗
PubMed2003

Transients of the force and surface mechanomyogram during cat gastrocnemius tetanic stimulation.

The aim of the study was to investigate the time relationship between force and muscle surface displacement, detected as the surface mechanomyogram (MMG) by a laser distance sensor, in the transient phases of a tetanic stimulation. For this purpose the motor nerve of the exposed medial gastrocnemius of four cats was supramaximally stimulated at 30, 40 and 50 Hz for 9 s. Force was detected by a transducer connected at the distal tendon while MMG was measured after pointing the laser beam at the muscle belly. We found that the MMG always anticipated and trailed the force changes during the on- and off-phase of the tetani, respectively. Independently of the stimulation rate, the half-times of the two signals were: on-phase, about 76 ms for force and 33 ms for MMG; off-phase, about 83 ms for force and 132 ms for MMG. There are two main comments to make about these results. First, during the on-phase the shortening of the contractile elements results at first in a muscle geometry change with low output force. After this, when the slack of the elastic-connective tissue has been taken up, the tension is efficiently transmitted to the tendon. Second, the different force and MMG dynamics in the on- and off-phases determine a counter-clockwise hysteresis with more force produced at a given muscle surface displacement during relaxation. To explain the results, the possible specific roles of some components of the muscle mechanical model, muscle mechanical properties and intra-muscular phenomena taking place during contraction have been discussed.

Animals↗
PubMed2003

Chronic hypobaric hypoxia does not affect electro-mechanical muscle activities during sustained maximal isometric contractions.

The aim of the study was to evaluate the influence of chronic hypobaric hypoxia [43 days at 5050 m above sea level, a.s.l.] on the electrical and mechanical activities of the elbow flexor and knee extensor muscles during sustained maximal isometric contractions. Seven subjects participated in this study. The maximal voluntary contraction (MVC) of the two muscle groups was assessed. The subjects were then asked to perform a sustained MVC for 1 min, during which surface EMG and MMG signals were recorded before (SL) and after 43 days at high altitude (HA). From the time and frequency domain analysis of the surface EMG and MMG, the root mean square (RMS) and the mean frequency (MF) were then calculated. After HA exposure, in both the investigated muscle groups the results showed that: (1) the MVC did not change; (2) the maximum force decay during the sustained MVC was similar; (3) surface EMG and MMG parameters did not show any statistical difference. These data suggest that exposure to HA did not affect the electrical and mechanical properties of the two investigated muscle groups. We conclude that exposure to chronic hypobaric hypoxia seems to have no effect on the central motor drive or on muscle performance during sustained maximal isometric contractions of the active muscles.

Acclimatization↗
PubMed2003

The surface mechanomyogram as a tool to describe the influence of fatigue on biceps brachii motor unit activation strategy. Historical basis and novel evidence.

The surface mechanomyogram (MMG) (detectable at the muscle surface as MMG by accelerometers, piezoelectric contact sensors or other transducers) is the summation of the activity of single motor units (MUs). Each MU contribution is related to the pressure waves generated by the active muscle fibres. The first part of this article will review briefly the results obtained by our group studying the possible role of motor unit recruitment and firing rate in determining the characteristics of the MMG during stimulated and voluntary contractions. The second part of this article will study the MMG and EMG during a short isometric force ramp from 0 to 90% of the maximal voluntary contraction (MVC) in fresh and fatigued biceps brachii. The aim is to verify whether changes in motor unit activation strategy in voluntarily fatigued muscle could be specifically reflected in the time and frequency domain parameters of the MMG. MMG-RMS vs. %MVC: at fatigue the MMG-RMS did not present the well known increment, when effort level increases, followed by a clear decrement at near-maximal contraction levels. MMG-MF vs. %MVC: compared to fresh muscle the fatigued biceps brachii showed an MF trend significantly shifted towards lower values and the steeper MF increment, from 65 to 85% MVC, was not present. The alteration in the MMG and EMG parameters vs. %MVC relationships at fatigue seems to be related to the impossibility of recruiting fast, but more fatigable MUs, and to the lowering of the global MUs firing during the short isometric force ramp investigated.

Acceleration↗
PubMed2004

Mechanomyographic responses in human biceps brachii and soleus during sustained isometric contraction.

The purpose of this study was to elucidate the responses of the mechanomyogram (MMG) from two apparently different muscles (biceps brachii and soleus) during a sustained voluntary contraction at 50% maximum voluntary contraction. The MMG and surface electromyogram (EMG) were recorded from human biceps brachii and soleus during sustained elbow flexion and plantar flexion, respectively. Results indicated that the slope coefficient of rise in EMG amplitude as a function of time for the biceps was significantly greater than that for the soleus ( P<0.001). On the contrary, the MMG amplitude of the biceps showed a significant increase during the initial phase of sustained contraction ( P<0.05); however, when exhaustion was approached the amplitude declined significantly ( P<0.05). In the soleus muscle the decrease in MMG amplitude toward exhaustion occurred to a much lesser extent than that observed in the biceps. This difference could be attributed to the nature of the fusion state of the underlying muscle fibers. That is, the great extent of fusion observed in the biceps may be as a result of a greater quantity of fatigable motor units. In addition, the absence of MMG reduction in the soleus would indicate the absence of fatigue-induced slowing of contractile machinery and/or the lack of full activation (tetanus) of muscle fibers even at the exhaustion phase of plantar flexion.

Adult↗
PubMed2004

Muscle tissue oxygenation, pressure, electrical, and mechanical responses during dynamic and static voluntary contractions.

Dynamic muscle contractions have been shown to cause greater energy turnover and fatigue than static contractions performed at a corresponding force level. Therefore, we hypothesized that: (1) electro- (EMG) and mechanomyography (MMG), intramuscular pressure (IMP), and reduction in muscle oxygen tension (rTO(2)) would be larger during dynamic (DYN) than intermittent static (IST) low force contractions; and that (2) oxygen tension would remain lower in the resting periods subsequent to DYN as compared to those following IST. Eight subjects performed elbow flexions with identical time-tension products: (1) DYN as a 20 degrees elbow movement of 2 s concentric and 2 s eccentric followed by a 4 s rest; and (2) IST with a 4 s contraction followed by a 4 s rest. Each session was performed for 1 min at 10 and 20% of the maximal voluntary contraction (MVC). The force, bipolar surface EMG, MMG, IMP, rTO(2) were measured simultaneously from the biceps brachii, and the data presented as the mean values together with the standard error of the means. Comparison of the corresponding time periods showed the EMG(rms) and MMG(rms) values to be larger during DYN than IST (concentric phase: DYN vs IST were 14.2 vs 9.4, and 22.0 vs 15.9%(max)-EMG(rms); eccentric phase: in DYN, the MMG was approximately 1.5 and approximately 2.0-fold IST at 10 and 20%MVC, respectively). In contrast, the IMP of the concentric phase in DYN was lower than in IST (2.3 vs 29.5 and 10.9 vs 42.0 mmHg at 10 and 20%MVC, respectively), and a similar picture was seen for the eccentric phase. However, no differences were seen in rTO(2) in either the contraction or the rest periods. In a prolonged rest period (8 s) after the sessions, DYN but not IST showed rTO(2) above baseline level. In conclusion, rTO(2) in DYN and IST were similar in spite of major differences in the MMG and EMG responses of the muscle during contraction periods. This may relate to the surprisingly lower IMP in DYN than IST.

Biomechanical Phenomena↗
PubMed2005

The effect of postactivation potentiation on the mechanomyogram.

To examine whether postactivation potentiation (PAP) was related to changes in the electromyogram (EMG) and in the mechanomyogram (MMG), evoked twitch torque properties were compared before and after a 10 s plantar flexion MVC in ten male subjects. Peak twitch torque (Pt), and the peak acceleration of the twitch torque development (d2T/dt2) were measured from electrical tibial nerve stimulation. In addition, from the medial gastrocnemius muscle, peak to peak MMG (p-p MMG) by means of accelerometer, and peak to peak EMG (M-wave) amplitudes were recorded. Immediately (2 s) following the MVC there were significant increases in Pt (47%), d2T/dt2 (86%), and p-p MMG (70%), but no change in the M-wave. At 2 s, 15 s, 30 s after the MVC, individual percent changes in p-p MMG were significantly and positively correlated with individual percent changes in both Pt and d2T/dt2. These results indicate that evoked MMG reflects acute enhanced force output elicited by PAP, and that the increases in twitch contraction properties represent intrinsic mechanical changes of the muscle, that are not associated with electrical changes. Furthermore, measurements of the evoked p-p MMG signal following PAP support the utility of describing the gross lateral movement phase of the MMG signal.

Action Potentials↗
PubMed2000

In vivo human triceps surae and quadriceps femoris muscle function in a squat jump and counter movement jump.

An optic fibre method was used to measure in humans in vivo Achilles (ATF) and patellar tendon forces (PTF) during submaximal squat jumps (SJ) and counter movement jumps (CMJ). Normal two-legged jumps on a force plate and one-legged jumps on a sledge apparatus were made by four volunteers. Kinetics, kinematics, and muscle activity from seven muscles were recorded. The loading patterns of the tendomuscular system differed among the jumping conditions, but were similar when the jumping height was varied. Peak PTF were greater than ATF in each condition. In contrast to earlier simulation studies it was observed that tendomuscular force could continue to increase during the shortening of muscle-tendon unit in CMJ. The concentric tendomuscular output was related to the force at the end of the stretching phase while the enhancement of the output in CMJ compared to SJ could not be explained by increases in muscle activity. The stretching phase in CMJ was characterised by little or no electromyogram activity. Therefore, the role of active stretch in creating beneficial conditions for the utilisation of elastic energy in muscle was only minor in these submaximal performances. The modelling, as used in the present study, showed, however, that tendon underwent a stretch-shortening cycle, thus having potential for elastic energy storage and utilisation. In general, the interaction between muscle and tendon components may be organised in a manner that takes advantage of the basic properties of muscle at given submaximal and variable activity levels of normal human locomotion.

Achilles Tendon↗
PubMed2000

Mechanomyographic and electromyographic responses during submaximal cycle ergometry.

The purpose of this study was to examine the mechanomyographic (MMG) and electromyographic (EMG) responses during continuous, cycle ergometer workbouts performed at constant power outputs. Eight adults [mean (SD) age, 21.5 (1.6) years] volunteered to perform an incremental test to exhaustion for the determination of peak power (Wpeak) and four, 15-min (or to exhaustion) rides at constant power outputs of 50%, 65%, 80%, and 95% Wpeak. Piezoelectric crystal contact sensors were placed on the vastus lateralis (VL) and vastus medialis (VM) muscles to record the MMG signals. Bipolar surface electrode arrangements were placed on the VL and VM to record the EMG signals. Five-second samples of the MMG and EMG signals were recorded every 30 s at power outputs of 50%, 65%, and 80% Wpeak, and every 15 s at 95% Wpeak. The amplitudes of the selected portions of the signals were normalized to the first values recorded during the continuous rides, and regression analyses were used to determine whether the slope coefficients for the MMG and EMG versus time relationships were significantly (P < 0.05) different from zero. The results indicate that EMG amplitude increased (range of slope coefficients: 0.03-0.56) during the continuous rides for both muscles at all four power outputs (except the VM at 50% Wpeak), while MMG amplitude increased (slope coefficient at 95% Wpeak for VM = 0.19), decreased (range of slope coefficients for VL and VM at 50% and 65% Wpeak = -0.14 to -0.24), or remained unchanged (range of slope coefficients for VL and VM at 80% Wpeak and VL at 95% peak = -0.06 to 0.12) depending on the power output. The patterns of the MMG responses, however, were similar for the VL and VM muscles, except at 95% Wpeak. Fatigue-induced changes in motor-unit recruitment and discharge rates, or muscular compliance may explain the differences between power outputs in the patterns of the MMG amplitude responses.

Adult↗
PubMed1997

Mechanomyography of the human quadriceps muscle during incremental cycle ergometry.

The mechanical activity of the human quadriceps muscle during maximal incremental cycle ergometry was investigated by mechanomyography (MMG). MMG and surface electromyography (EMG) recordings of vastus lateralis muscle activity were obtained from nine males. Cycle ergometry was performed at 60 rev/ min and work load was incremented step wise by 20 W (3.2 Nm) every minute until volitional fatigue. The mean amplitudes of MMG (mMMG) and EMG (mEMG) during the contraction phase were calculated from the last six contractions in each load. The duration, load and work rate of exercise at exhaustion were 13.3 (1.6) min, 44.1 (5.5) Nm, 276.7 (34.7) W, respectively. A linear relationship between mMMG and load was evident in each subject (r = 0.868-0.995), while mEMG seemed to dissociate as the load became greater. In the grouped mean data, mMMG was linearly related to load whether aligned to the absolute (r = 0.995) or maximal (r = 0.995) load. Involvement of the noise component was further investigated by studying passive cycling by four subjects. Pedals were rotated passively for the first half of each stage (PAS) and the subject then pushed the pedals for the second half (ACT). In the lighter load region, the mMMG of ACT was as small as that of PAS. However, the change in the mMMG of PAS was very small compared with that of ACT. In conclusion, this study demonstrates a linear relationship between the mMMG of the quadriceps muscle and work load during maximal incremental cycle ergometry. The effect of movement noise was thought to be small and stable.

Adult↗
PubMed1997

Mechanomyography and oxygen consumption during incremental cycle ergometry.

The purpose of this investigation was to describe and compare the relationships for mechanomyography (MMG) and oxygen consumption rate (VO2) versus power output during incremental cycle ergometry. Twenty four adult males [mean (SD) age, 22.1 (2.0) years] volunteered to perform an incremental test to exhaustion on a cycle ergometer. A MMG piezoelectric recording device was placed mid-thigh over the vastus lateralis muscle and VO2 was measured using standard open circuit procedures. The r2 values for the MMG and VO2 versus power output relationships ranged from 0.79 to 0.99 and 0.97 to 0.99, respectively. In 20 of the 24 subjects there was no significant (P > 0.10) difference between the slope values for the normalized MMG and VO2 (expressed as a percentage of maximal values) versus power output relationships. The results of this study indicate that MMG procedures can be used to quantify muscular activity and monitor changes in exercise intensity during cycle ergometry. Furthermore, the present findings demonstrated a close association between the mechanical (MMG) and metabolic (VO2) aspects of muscular contraction during incremental cycle ergometry.

Adult↗
PubMed1998

Summation of elementary phonomyograms during isometric twitches in humans.

To study its summation principle, the phonomyogram (PMG) from the first interosseus dorsalis muscle was recorded in five subjects during single twitches evoked by electrical stimulation over the motor point. By increasing the current pulse from threshold to maximal intensity, PMG amplitude increased linearly with motor unit recruitment. The twitch amplitude-intensity relationship was also linear. The PMG amplitude was therefore linearly related to the external force. For all these relationships highly significant correlation coefficients were found. These relationships were interpreted as being a consequence of an orderly recruitment, although, contrary to what happens during voluntary contraction, the largest and strongest motor units were recruited before the smallest and weakest ones during axon electrical stimulation. The PMG onset always preceded twitch onsets as indicated by latency measurements [mean 3.2 (SD 1.3) ms versus 11.5 (SD 3.9) ms, respectively]. Moreover, PMG and twitch latencies may have been significantly reduced by recruitment, suggesting that orderly recruitment influenced both PMG amplitude and occurrence. These results were interpreted as being the result of the summation of elementary PMG from every contracting motor unit and the stiffness change of the muscle medium occurring with recruitment.

Acoustics↗
PubMed1998

The effect of leg flexion angle on the mechanomyographic responses to isometric muscle actions.

The purpose of this investigation was to examine the effect of leg flexion angle on the relationship between mechanomyographic (MMG) amplitude and isometric torque production. Adult males (n = 9) performed isometric muscle actions of the leg extensors at 25, 50, 75, and 100 percent maximal voluntary contraction (%MVC) on a calibrated CYBEX 6000 dynamometer at 25, 50, and 75 degrees below full extension. A piezoelectric MMG recording device was placed over the mid-portion of the rectus femoris. At 25 degrees of leg flexion, the MMG amplitude increased to 100%MVC. At 50 and 75 degrees of leg flexion, however, MMG amplitude increased to 75%MVC, and then did not change significantly (P > 0.05) between 75 and 100%MVC. These findings indicate that the MMG amplitude-isometric torque relationship is joint angle specific and may be the result of leg flexion angle differences in: (1) muscle stiffness, or (2) motor unit activation strategies.

Adult↗