Anesth Analg 2005;100:718-721
© 2005 International Anesthesia Research Society
doi: 10.1213/01.ANE.0000144067.42615.AD
ANESTHETIC PHARMACOLOGY
Dominance of the Hand Does Not Change the Phonomyographic Measurement of Neuromuscular Block at the Adductor Pollicis Muscle
Guillaume Michaud,
Guillaume Trager, MSc,
Stéphane Deschamps, MSc, and
Thomas M. Hemmerling, MD, DEAA
From the Neuromuscular Research Group (NRG), Department of Anesthesiology, Centre Hospitalier de l'Université de Montréal (CHUM) Hôtel-Dieu, Université de Montréal, Montréal, Canada
Address correspondence and reprint requests to T. M. Hemmerling, MD, DEAA, Department of Anesthesiology, Université de Montréal, Hôtel-Dieu, 3580, rue St-Urbain, Montréal (Québec) H2W 1T8, Canada. Address e-mail to thomashemmerling_2000{at}yahoo.com.
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Abstract
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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 T1/T0 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.
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Introduction
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Phonomyography (PMG) is a novel method for recording neuromuscular blockade (NMB) with high sensitivity and applicability at all muscles. It can be used at several muscles, including the adductor pollicis muscle (1), the adducting laryngeal muscles (2), and the corrugator supercilii (3). PMG is based on the fact that muscles create low-frequency sounds when contracting via lateral movement of the muscle fibrils. Muscles of the hand, especially the adductor pollicis muscle, have long been used in research and clinical practice as reference sites for neuromuscular monitoring. Monitoring of this muscle is easy and essential for determination of complete recovery of neuromuscular transmission after NMB during surgery. It is known from electromyographic studies that hand dominance can cause adaptations in the fiber composition of the dominant muscles (4,5). However, few studies have investigated how the dominance of the hand influences measurements of NMB. The focus of this study is to determine the influence of the dominance of the hand on measurements of NMB at the adductor pollicis muscle using PMG.
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Methods
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After approval of the local ethics committee and obtaining informed consent, 14 patients undergoing general surgery were included in the study. Patients with neuromuscular, hepatic, or renal disease and patients receiving medications known to interact with NMB drugs were excluded. After arrival in the operating room, routine monitoring (noninvasive arterial blood pressure, pulse oximetry, five-lead electrocardiography) was applied. Anesthesia was induced with remifentanil 0.25–0.5 µg · kg–1 · min–1 followed by propofol 2 – 2.5 mg/kg. After loss of consciousness and ventilation via face mask for 2 min with 100% oxygen, a laryngeal mask airway (size 4 for women, size 5 for men; LMA, London, UK) was inserted and controlled ventilation started with minute ventilation set to maintain a Petco2 of 25–35 mm Hg. Anesthesia was maintained with 1–1.5 MAC of sevoflurane in a gas mixture of 30% oxygen in air to maintain a bispectral index (BIS) of 50 (A-2000 monitoring system; Aspect Medical Company, Newton, MA). Analgesia was provided by remifentanil 0.05–0.25 µg kg–1min–1 throughout surgery.
A small piezoelectric microphone (1.6 cm diameter, Model 1010, Grass Instruments, Astro-Med, Inc., West Warwick, RI; frequency response: 2.5 Hz to 5 kHz, signal output: 20–40 mV into 1 M
) was attached to the middle of the thenar mass of each hand (dominant and nondominant) using gluing tape to record the acoustic signals produced by the contraction of the adductor pollicis muscle (Fig. 1). Each arm was fixed to a routine armboard with tape to limit movements from the arm resulting from hand contraction. The microphone signals were amplified and bandpass filtered between 0.5 Hz and 1000 Hz using an AC/DC amplifier. The PMG signals were continuously sampled at 100 Hz using the Polyview® software package, digitized, and stored on a portable microcomputer. The twitch amplitude from PMG signals was measured peak-to-peak.
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Figure 1. Positioning of the microphones to monitor neuromuscular blockade of the adductor pollicis (thenar region) on each hand – dominant hand shown. Arm was fixed to a routine armboard using tape.
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In all patients, the ulnar nerve was stimulated at the wrist (the same positioning was used on both sides) with train-of-four supramaximal stimulation each 12 s via surface electrodes using a constant current stimulator (Innervator®, Fisher and Paykel Healthcare, Auckland, New Zealand). Current intensity was set between 0 and 70 mA. Stimulation intensity was the same for both hands. Heating blankets over both upper extremities were used to maintain temperature throughout the observation period. When all signals were stable and free of artifacts, mivacurium 0.2 mg/kg was injected within 5 s into a fast flowing solution of Ringer's lactate. Location of venous access was established according to surgical needs. Onset, maximum effect, and offset of NMB were determined. Recordings of signals were continued until train-of-four ratio was more than 0.9 in all patients.
The first twitch response was used to analyze onset time (time to reach maximum decrease of twitch response) and time to reach 25%, 50%, 75%, and 90% of control twitch response. The maximum effect was determined as the maximum decrease of the twitch response and was also recorded. Train-of-four ratios of 0.5, 0.7, 0.8, and 0.9 were recorded.
Sample size was calculated to achieve a power of 0.9 with an estimated difference of 1 min at a standard deviation of 0.25 min of time to reach 25% of control value between both hands. The results are expressed as mean and sd. Paired Student's t-tests were performed. P < 0.05 was regarded as showing a significant difference. A Bland-Altman test was performed using all the twitches of each patient between the dominant and the nondominant hand. Correlation between dominant and nondominant hand of the same patient was also calculated using the Pearson test.
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Results
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We were able to obtain pharmacodynamic data in all 14 patients (five men and nine women) with a mean age of 48.2 ± 19.2 years, mean weight of 76.8 ± 11.1 kg, and mean height of 170.2 ± 12.3 cm. Twelve patients were right-handed and two patients were left-handed. Control amplitude height was not statistically different between the dominant hand and the nondominant hand at 1.13 mV ± 0.66 mV versus 1 mV ± 0.7 mV. Supramaximal stimulation current was equal for both sides with a mean of 50 ± 10 mA. No statistical difference was found for the pharmacodynamic variables from the dominant and nondominant hand for the same patient (Fig. 2). Correlation between data from dominant and nondominant hand were r = 0.95 (Fig. 3). Bland-Altman testing between dominant versus nondominant hand revealed a bias of –0.57% and limits of agreement of –17.9% to 16.7% for all signals (Fig. 4). The position of the microphone over thenar mass was checked before and after the procedure to detect possible movement of the microphones. In no patient could movement of the microphone be observed.
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Figure 2. A, all twitches as means (sd) of all patients for dominant hand (gray triangle) and nondominant hand (black square). B, train-of-four ratios as means (sd) of all patients for dominant hand (gray triangle) and nondominant hand (black square).
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Figure 3. Bland-Altman plot for dominant and nondominant hand. Two patients were left-handed and 12 patients were right-handed.
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Discussion
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Our results show a good correlation and minimal bias between the dominant and nondominant adductor pollicis muscle for all pharmacodynamic values. The dominance of the hand does not influence NMB as measured via PMG.
The results of studies investigating the influence of the hand dominance on neuromuscular transmission and NMB are contradictory. It is known from electromyographic studies that hand dominance can cause alterations in the fiber composition of the dominant muscles (4,5). In those studies, motor unit recruitment and firing behavior of the first dorsal interosseous muscle from dominant and nondominant hands were compared. Slower firing rates and recruitment thresholds in the dominant muscles suggested an increased percentage of slow twitch fibers. Those adaptations could potentially lead to a different response to NMB drugs. A study by Caldwell et al. (6) investigating NMB at the adductor pollicis muscle via mechanomyography suggested a different sensitivity between the dominant and nondominant hands. In another study using mechanomyography at the thumb, Lee et al. (7) contradicted those results showing no difference in onset time, peak effect, T25%, and T75% between the two hands of the same volunteers. PMG measures sound evoked by muscle contraction. The morphology of the muscle, therefore, could have influenced the amplitude of the sound. However, we could not find any statistical difference between adductor pollicis muscles of opposite hands.
Factors other than hand dominance could have influenced our measurements. Slight movements of the microphone relative to the skin during surgery and movement of the arm could lead to a significant bias. Therefore, great care was taken to solidly fix the microphones to the skin and to minimize arm movement caused by evoked contractions. Arm and microphone positions were also checked before and after the procedure to detect any potential movement of position during the measurement period.
In conclusion, this study shows minimal bias and excellent correlation between the dominant and nondominant adductor pollicis muscle. According to the results, both hands can be used interchangeably to assess NMB at the adductor pollicis muscle.
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References
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- Hemmerling TM, Michaud G, Babin D, et al. Phonomyography and Mechanomyography can be used interchangeably to measure neuromuscular block at the adductor pollicis muscle. Anesth Analg 2004;98:377–81.[Abstract/Free Full Text]
- Hemmerling TM, Babin D, Donati F. Phonomyography as a novel method to determine neuromuscular blockade at the laryngeal adductor muscles: comparison with the cuff pressure method. Anesthesiology 2003;98:359–63.[ISI][Medline]
- Hemmerling TM, Donati F, Beaulieu P, Babin D. Phonomyography of the corrugator supercilii muscle: signal characteristics, best recording site and comparison with acceleromyography. Br J Anaesth 2002;88:389–93.[Abstract/Free Full Text]
- Adam A, De Luca CJ, Erim Z. Hand dominance and motor unit firing behavior. J Neurophysiol 1998;80:1373–82.[Abstract/Free Full Text]
- Kamen G, Greenstein SS, De Luca CJ. Lateral dominance and motor unit firing behavior. Brain Res 1992;576:165–7.[ISI][Medline]
- Caldwell JE, Szenohradszky J, Segredo V, et al. The pharmacodynamics and pharmacokinetics of the metabolite 3-desacetylvecuronium (ORG 7268) and its parent compound, vecuronium, in human volunteers. J Pharmacol Exp Ther 1994;270:1216–22.[Abstract/Free Full Text]
- Lee GC, Iyengar S, Szenohradszky J, et al. Improving the design of muscle relaxant studies. Anesthesiology 1997;86:48–54.[ISI][Medline]
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Abstract
Introduction
