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Biomedical subjects

Thomas M Hemmerling

Publications and source records attributed to Thomas M Hemmerling.

At least 19 recordsLinked to original sources
PubMed2007

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.

Diaphragm↗
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↗
PubMed2005

A priming technique accelerates onset of neuromuscular blockade at the laryngeal adductor muscles.

PURPOSE: Priming is a known technique to accelerate onset of neuromuscular blockade (NMB). Its effect on NMB of the larynx has not been studied yet. METHODS: We compared a priming technique with a bolus application of rocuronium on the onset of NMB at the laryngeal adductor and the adductor pollicis muscles (AP). In 30 female patients, after induction of anesthesia a tube with a surface electrode was placed into the trachea prior to the administration of any neuromuscular blocking agent to monitor electromyography (EMG) of the laryngeal adductor muscles. Neuromuscular monitoring consisted of EMG of the laryngeal adductor muscles and the left AP. Patients were randomized into two groups. After transcutaneous stimulation of the recurrent laryngeal nerve and ulnar nerve, a bolus of rocuronium 0.6 mg x kg(-1) (Bolus group) or a priming dose of rocuronium 0.06 mg x kg(-1) followed by rocuronium 0.54 mg x kg(-1) three minutes later (Priming group) were injected. Lag time, onset 90%, onset time and peak effect of NMB were recorded and compared; a P < 0.05 was considered significant. RESULTS: The onset 90% and onset time measured at the laryngeal adductor muscles (onset: 44.7 +/- 7.4 vs 74.0 +/- 23.8 sec) and at the AP (onset: 105.4 +/- 29.9 vs 139.2 +/- 51.5 sec) were significantly shorter in the Priming group than in the Bolus group. Within groups, the onset times were significantly shorter at the laryngeal muscles in comparison to AP. CONCLUSION: Our results indicate that a priming technique with rocuronium significantly accelerates the onset of NMB at the laryngeal adductor muscles. Our results further support the use of rocuronium as an alternative to succinylcholine for rapid sequence induction.

Adult↗
PubMed2005

Awake cardiac surgery using a novel anesthetic technique.

PURPOSE: We describe the first published cases of awake cardiac surgery in Canada. In addition, a novel anesthetic technique consisting of combined femoral block/high epidural thoracic anesthesia is presented. CLINICAL FEATURES: Two patients, both 65 yr of age and with good left ventricular function, were scheduled to undergo off-pump coronary artery bypass grafting (OPCAB) for two grafts each. Anesthesia consisted of combined femoral 3:1 block and high thoracic epidural anesthesia. Both surgeries proceeded without hemodynamic or respiratory complications; in both cases, opening of the pleural spaces was treated with insertion of thoracic drainage tubes. Both patients were transferred to the postanesthesia care unit immediately after surgery and six hours later to the cardiac surgical ward. Both patients were discharged from the hospital within five days of surgery. CONCLUSION: We conclude that awake OPCAB is feasible using a combined femoral block/high thoracic epidural anesthesia technique which allows cardiac surgery and harvesting of the saphenous vein. Further clinical experience is required to define the technical limitations of this technique before randomized studies should be undertaken to better define the role of awake procedures in the future of cardiac surgery.

Aged↗
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↗
PubMed2005

Immediate extubation after aortic valve surgery using high thoracic epidural analgesia or opioid-based analgesia.

OBJECTIVE: Fast-track anesthesia has gained widespread use in cardiac centers around the world. No study has been published focusing on immediate extubation after aortic valve surgery. This study examines the feasibility and hemodynamic stability of immediate extubation after simple or combined aortic valve surgery using either thoracic epidural analgesia or opioid-based analgesia. DESIGN: Prospective audit, pilot study. SETTING: Single-institution university medical center. PARTICIPANTS: Adult patients undergoing aortic valve replacement (N = 45). INTERVENTIONS: Forty-five patients undergoing aortic valve surgery with an ejection fraction of more than 30% were included in this prospective audit. Induction of anesthesia was done using fentanyl, 2 to 4 mug/kg, propofol, 1 to 2 mg/kg, and endotracheal intubation facilitated by rocuronium; anesthesia was maintained using sevoflurane titrated according to bispectral index (BIS [BIS target: 50]). Perioperative analgesia was provided by high thoracic epidural analgesia (TEA group, bupivacaine 0.125%, 6 to 14 mL/h) or fentanyl, up to 10 microg/kg, followed by patient-controlled analgesia with morphine (OPIOID group). MEASUREMENTS AND MAIN RESULTS: Success of extubation within 30 minutes after surgery was recorded. Hemodynamic data during surgery were compared by using an analysis of variance test; p < 0.05 was considered as showing a significant difference. Data presented as median (25th-75th percentile). In the TEA group, patients underwent simple aortic valve replacement (N = 21) or combined aortic valve surgery (N = 14), with additional coronary artery bypass grafting (N = 10) and replacement of the ascending aorta (Bentall, N = 4). In the OPIOID group, patients underwent simple aortic valve replacement (N = 5) or combined aortic valve surgery (N = 5), with additional aortocoronary bypass grafting (N = 2), replacement of the ascending aorta (Bentall, N = 2), and reconstruction of the mitral valve (N = 1). All 45 patients were extubated within 15 minutes after surgery. There was no need for reintubation; pain scores were lower in the TEA group than in the OPIOID group immediately after surgery and at 6 hours, 24 hours, and 48 hours after surgery. For the TEA group and OPIOID group, the pain scores were 0 (0-2), 0 (0-2), 0 (0-1.5), and 0 (0-0) and 5 (4-5.75), 4 (3-4.5), 4 (3.25-4), and 1 (0-2.5), respectively. During and up to 6 hours after surgery, there was no significant hemodynamic difference between the TEA and OPIOID groups. Eighteen of 45 patients needed temporary pacemaker activation. There were no epidural hematoma or neurologic complications related to TEA. CONCLUSION: Immediate extubation is feasible after aortic valve surgery using either high thoracic epidural analgesia or opioid-based analgesia; both techniques maintain hemodynamic stability throughout surgery. TEA provides superior pain control.

Adult↗
PubMed2005

Bispectral index as an indicator of cerebral hypoperfusion during off-pump coronary artery bypass grafting.

Bradycardia and hypotension are common during off-pump coronary artery bypass grafting (OPCAB). We present a case of possible reversible global cerebral hypoperfusion during distal grafting of the left circumflex coronary artery. The bispectral index (BIS) suddenly decreased from values of 45-50 to 0 during distal grafting. Neurologic evaluation after immediate tracheal extubation in the operating room was normal and the 58 yr old patient did not suffer any neurologic sequelae. Postoperative recovery was uneventful and the patient was discharged 5 days after surgery. Cerebral hypoperfusion is a possible complication during OPCAB. BIS monitoring in OPCAB could be an indicator of cerebral hypoperfusion.

Angina Pectoris↗
PubMed2005

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.

Adult↗
PubMed2005

An external monitoring site at the neck cannot be used to measure neuromuscular blockade of the larynx.

Using phonomyography, a new monitoring technique of neuromuscular blockade (NMB), we compared NMB after mivacurium 0.1 mg/kg at the lateral cricoarytenoid muscle (LCA) with a possible external monitoring site of the larynx. In 12 patients, data were obtained at both sites using phonomyography. Anesthesia was induced with remifentanil 0.25-0.5 microg . kg(-1) . min(-1) followed by propofol 2-3 mg/kg. A small piezo-electric microphone was positioned beside the vocal cords into the muscular process at the base of the arytenoid cartilage to record acoustic signals from the contraction of the LCA. A second microphone was positioned at an external site, lateral to the trachea, just below the thyroid notch. The recurrent laryngeal nerve was stimulated supramaximally using train-of-four (TOF) stimulation every 12 s. Onset, maximum effect, and offset of NMB were measured and compared. Peak effect, time to reach (T) 25%, 75%, and 90% of control twitch response, and TOF recovery to TOF ratios 0.5-0.8 were significantly longer at the external site. The onset time was not significantly different between the two sites. We used phonomyography with a microphone placed at the neck to evaluate the possibility to externally monitor NMB at the larynx. When compared with LCA, we found a more pronounced peak effect and longer offset of NMB. The acoustic signals recorded at this external site are unlikely to stem from laryngeal muscle contraction but are rather a result of contraction of the strap muscles of the neck.

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↗
PubMed2004

Ultra-fast-track anesthesia in off-pump coronary artery bypass grafting: a prospective audit comparing opioid-based anesthesia vs thoracic epidural-based anesthesia.

PURPOSE: To examine the feasibility of immediate extubation after off-pump coronary artery bypass grafting (OPCAB) using opioid based analgesia or high thoracic epidural analgesia (TEA) and compare postoperative analgesia with continuous TEA vs patient-controlled analgesia (PCA). METHODS: One hundred consecutive patients undergoing OPCAB were included in this prospective audit. After induction of anesthesia using fentanyl 2 to 5 microg.kg(-1), propofol 1 to 2 mg.kg(-1) and endotracheal intubation facilitated by rocuronium, anesthesia was maintained using sevoflurane titrated according to bispectral index monitoring. Perioperative analgesia was provided by TEA (n = 63) at the T3/T4 interspace or T4/T5 interspace using bupivacaine 0.125% 8 to 14 mL.hr(-1) and repetitive boluses of bupivacaine 0.25% during surgery. In patients who were fully anticoagulated or refused TEA, perioperative analgesia was achieved by i.v. fentanyl boluses (up to 15 microg.kg(-1)) and remifentanil 0.1 to 0.2 microg.kg(-1).min(-1), followed by morphine PCA after surgery (n = 37). Maintenance of body temperature was achieved by a heated operating room and forced-air warming blankets. RESULTS: Ninety-five patients were extubated within 25 min after surgery (PCA, n = 33; TEA, n = 62). Five patients were not extubated immediately because their core temperature was lower than 35 degrees C. One patient was re-intubated because of agitation (TEA group); one was re-intubated because of severe pain and morphine-induced respiratory depression (PCA group). Pain scores were low after surgery, with pain scores in the TEA group being significantly lower immediately, at six hours, 24 hr and 48 hr after surgery (P < 0.05). CONCLUSION: Immediate extubation is possible after OPCAB using either opioid-based analgesia or TEA. TEA provides significantly lower pain scores after surgery in comparison to morphine PCA.

Analgesia, Patient-Controlled↗
PubMed2004

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

UNLABELLED: 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.

Acoustic Stimulation↗
PubMed2004

Simultaneous determination of neuromuscular blockade at the adducting and abducting laryngeal muscles using phonomyography.

UNLABELLED: Phonomyography (PMG) is a new method for measuring neuromuscular blockade (NMB) at the larynx. In this study, we used PMG to compare NMB at the posterior cricoarytenoid (PCA) and the lateral cricoarytenoid muscle (LCA) in humans. Twelve patients were included in this study. Endotracheal intubation was performed without aid of neuromuscular blocking drugs. One small condenser microphone was inserted beside the vocal cords into the muscular process at the base of the arytenoid cartilage to record acoustic responses of the LCA (vocal cord adduction), and a second microphone was placed behind the larynx to measure NMB of the PCA (vocal cord abduction). Stimulation of the recurrent laryngeal nerve was performed using superficial electrodes placed at the neck (midline between jugular notch and cricoid cartilage) using train-of-four (TOF) stimulation every 12 s. After supramaximal stimulation, mivacurium 0.1 mg/kg was injected and onset, peak effect, and offset of NMB measured and compared using t-test (P < 0.05). The data are presented as mean (SD). Peak effect, onset time, and early recovery to 25% of control twitch height were not significantly different between PCA and LCA at 86% (13) versus 78% (16), 2.3 min (0.45) versus 2.3 min (1.0), and 9.55 min (3.05) versus 8.5 min (4.7), respectively. However, recovery to 75%, 90% of control twitch height, and recovery to a TOF ratio of 0.8 were significantly longer at the PCA than at the LCA at 14 min (4) versus 11 min (5), 17 min (5) versus 11.8 min (5.6), and 17.5 min (5.6) versus 12.3 min (5.5), respectively. The authors conclude that recovery of NMB at the PCA takes longer than at the LCA in humans after mivacurium. IMPLICATIONS: After neuromuscular blockade in humans, the recovery of the ability to open the vocal cords takes longer than the ability to close the vocal cords.

Adult↗