Examining Awake Volunteer Pain Scores and Operator Ease of Use of a Novel Neuromuscular Blockade Monitor J. Ross Renew, MD; Ilana Logvinov, MSN, RN; Sorin J. Brull, MD, FCARCSI (Hon) Mayo Clinic, Jacksonville, FL © 2017 Mayo Foundation for Medical Education and Research Introduction Postoperative residual neuromuscular blockade is a significant problem that exposes patients to unnecessary risks (hypoxemia, airway obstruction, unpleasant subjective symptoms, longer recovery, delays in extubation, increased risk of postoperative pulmonary complications and cost). 1 The use of peripheral nerve stimulators is common to guide management of neuromuscular blocking agents (NMBAs). However, this technique relies on clinicians to subjectively determine the degree of fade in response to train-of-four (TOF) stimulation. This subjective assessment fails when TOF ratio is between 0.4 and 0.9, because this degree of fade cannot be appreciated by subjective means. In the normal, unblocked state, the TOF ratio is 1.0; the ratio decreases as an increasing number of receptors (>70%) are blocked by the NMBA, and when 75-80% or receptors are blocked, the ratio approaches 0. Once approximately 90-95% of receptors are blocked, the TOF stimulation produces no evoked responses (TOF count = 0). During recovery of neuromuscular block, the TOF count increases progressively from TOF count = 0 to TOF count 1, then 2, then 3, and ultimately TOF count = 4, at which point the TOF ratio again can be calculated. A sufficient recovery of block is defined as a TOF ratio ≥0.9. 2 Quantitative monitors that display, measure and calculate the amplitude of evoked muscle responses are therefore preferred to subjective evaluation, in order to help guide intraoperative management of neuromuscular blockade and accurately demonstrate complete recovery. Unfortunately, many of these quantitative monitoring techniques such as acceleromyography (AMG) and kinemyography (KMG) rely upon freely moving muscles to determine the level of neuromuscular block. Surgical positioning with the patient’s arms tucked to the side can often impede such movements, limit access to the hands, and preclude the use of these motion-based monitors. Electromyography (EMG) does not depend on freely moving muscles as the sensing electrodes measure electrical activity of the muscle that results from depolarization. 3 The authors describe their experience with a new EMG-based neuromuscular monitor, TetraGraph TM (Senzime, Uppsala, Sweden) (Figure 1) and the specially-designed electrodes (Figure 2), and compare the level of discomfort associated with neurostimulation in comparison with an existing monitor, the AMG-based TOF-Watch (Organon, Dublin, Ireland). Results VAS scores obtained with TetraGraph TM were significantly lower than those obtained with TOF- Watch at intensities greater than 30 mA (Table 1). All volunteers completed the trial, and there were no untoward reactions to the stimulations. The TetraGraph TM device interface was intuitive and provided a TOF ratio (100% ± 10%) that would be expected in healthy, awake adults. Conclusions The TetraGraph TM monitor is a hand-held EMG device that produces less painful neurostimulation than the TOF-Watch device in awake, healthy volunteers. The lower discomfort may be due to the larger stimulating area of the TetraGraph TM electrodes that decreases stimulating current density and likely, the pain associated with neurostimulation. The investigators found the monitor easy to use, and required less than a minute for set-up and calibration. The investigators will begin exploring intraoperative applications of the monitor. References 1. Murphy GS, Brull SJ. Residual neuromuscular block: lessons unlearned. Part I: definitions, incidence, and adverse physiologic effects of residual neuromuscular block. Anesth Analg 111(1):120-8 2. Capron F, Fortier LP, Racine S, Donati F. Tactile fade detection with hand or wrist stimulation using train-of-four, double-burst stimulation, 50-hertz tetanus, 100-hertz tetanus, and acceleromyography. Anesth Analg. 2006 May;102(5):1578-84. 3. Renew JR, Brull SJ. The effect of quantitative neuromuscular monitoring on the incidence of residual neuromuscular blockade and clinical outcomes. Curr Anesthesiol Rep. 2016; 6(2): 170-7. Disclosures Dr. Brull is a member of the Board of Directors of the Anesthesia Patient Safety Foundation (APSF), and Senzime AB. He has clinical research funded by Merck, Inc. (funds distributed to Mayo Clinic), and is a member of the Scientific Advisory Boards for The Doctors Company and ClearLine MD. Table 1 Visual Analog Scale (VAS) Scores Amplitude TOF-Watch TetraGraph P-value M SD CI M SD CI 20 mA 1.56 1.25 1.05-1.95 1.52 1.40 0.97-2.07 0.96 30 mA 3.11 1.58 2.72-3.95 2.89 1.93 2.13-3.65 0.35 40 mA 4.25 2.40 3.95-5.85 2.88 1.15 2.39-3.36 <0.0001 50 mA 4.75 2.23 4.54-6.40 4.08 2.38 3.08-5.09 0.04 Overall 3.35 2.24 3.34-4.26 2.80 1.97 2.42-3.19 0.001 M = Mean; SD = standard deviation; CI = Confidence interval with range 5-95% Figure 1 TetraGraph TM Figure 2 Specially-Designed Electrodes Methods After IRB approval, 10 adult volunteers gave oral informed consent to participate in the study. The skin overlying the ulnar nerve on the distal volar forearm was cleansed with alcohol and the TetraGraph TM stimulating electrodes were placed over this area, with the negative stimulating electrode placed distally to the positive stimulating electrode. One sensing electrode was placed on the hypothenar eminence over the belly of the abductor digiti minimi muscle, and the other sensing electrode was placed over the base of the 5th finger over the abductor digiti minimi muscle insertion site, to record the response of the muscle to ulnar nerve stimulation (Figure 3). An anchor visual analog scale (VAS) score (on an 11-point scale where 0=no pain and 10=the most intense pain ever experienced) was obtained in response to a single twitch stimulation at 30 mA to obtain a reference VAS for the volunteer. TOF stimulation at 20 mA, 30 mA, 40 mA, and 50 mA was delivered in random order, with the volunteer blinded to the intensity. VAS scores were obtained for each of these intensities, with each stimulation performed in triplicate at each of the 4 current amplitudes. The TOF-Watch was then applied to the opposite arm, with stimulating electrodes placed over the ulnar nerve on the distal volar forearm. The accelerometer was taped to the thumb and the preload device was applied, as per manufacturer recommendations. VAS scores were then obtained in triplicate as for TetraGraph TM . Figure 3 Sensing Electrode Placement Abstract Examining Awake Volunteer Pain Scores and Operator Ease of Use of a Novel Neuromuscular Blockade Monitor J. Ross Renew, MD; Ilana Logvinov, MSN, RN; Sorin J. Brull, MD, FCARCSI (Hon) Introduction Postoperative residual neuromuscular blockade is a significant problem that exposes patients to unnecessary risks (hypoxemia, airway obstruction, unpleasant subjective symptoms, longer recovery, delays in extubation, increased risk of postoperative pulmonary complications and cost). 1 The use of peripheral nerve stimulators is common to guide management of neuromuscular blocking agents (NMBAs). However, this technique relies on clinicians to subjectively determine the degree of fade in response to train-of-four (TOF) stimulation. This subjective assessment fails when TOF ratio is between 0.4 and 0.9, because this degree of fade cannot be appreciated by subjective means. In the normal, unblocked state, the TOF ratio is 1.0; the ratio decreases as an increasing number of receptors (>70%) are blocked by the NMBA, and when 75-80% or receptors are blocked, the ratio approaches 0. Once approximately 90-95% of receptors are blocked, the TOF stimulation produces no evoked responses (TOF count = 0). During recovery of neuromuscular block, the TOF count increases progressively from TOF count = 0 to TOF count 1, then 2, then 3, and ultimately TOF count = 4, at which point the TOF ratio again can be calculated. A sufficient recovery of block is defined as a TOF ratio ≥0.9. 2 Quantitative monitors that display, measure and calculate the amplitude of evoked muscle responses are therefore preferred to subjective evaluation, in order to help guide intraoperative management of neuromuscular blockade and accurately demonstrate complete recovery. Unfortunately, many of these quantitative monitoring techniques such as acceleromyography (AMG) and kinemyography (KMG) rely upon freely moving muscles to determine the level of neuromuscular block. Surgical positioning with the patient’s arms tucked to the side can often impede such movements, limit access to the hands, and preclude the use of these motion-based monitors. Electromyography (EMG) does not depend on freely moving muscles as the sensing electrodes measure electrical activity of the muscle that results from depolarization. 3 The authors describe their experience with a new EMG-based neuromuscular monitor, TetraGraph TM (Senzime, Uppsala, Sweden) (Figure 1) and the specially-designed electrodes (Figure 2), and compare the level of discomfort associated with neurostimulation in comparison with an existing monitor, the AMG-based TOF-Watch (Organon, Dublin, Ireland). Methods After IRB approval, 10 adult volunteers gave oral informed consent to participate in the study. The skin overlying the ulnar nerve on the distal volar forearm was cleansed with alcohol and the TetraGraph TM stimulating electrodes were placed over this area, with the negative stimulating electrode placed distally to the positive stimulating electrode. One sensing electrode was placed on the hypothenar eminence over the belly of the abductor digiti minimi muscle, and the other sensing electrode was placed over the base of the 5th finger over the abductor digiti minimi muscle insertion site, to record the response of the muscle to ulnar nerve stimulation (Figure 3). An anchor visual analog scale (VAS) score (on an 11-point scale where 0=no pain and 10=the most intense pain ever experienced) was obtained in response to a single twitch stimulation at 30 mA to obtain a reference VAS for the volunteer. TOF stimulation at 20 mA, 30 mA, 40 mA, and 50 mA was delivered in random order, with the volunteer blinded to the intensity. VAS scores were obtained for each of these intensities, with each stimulation performed in triplicate at each of the 4 current amplitudes. The TOF-Watch was then applied to the opposite arm, with stimulating electrodes placed over the ulnar nerve on the distal volar forearm. The accelerometer was taped to the thumb and the preload device was applied, as per manufacturer recommendations. VAS scores were then obtained in triplicate as for TetraGraph TM . Results VAS scores obtained with TetraGraph TM were significantly lower than those obtained with TOF-Watch at intensities greater than 30 mA (Table 1). All volunteers completed the trial, and there were no untoward reactions to the stimulations. The TetraGraph TM device interface was intuitive and provided a TOF ratio (100% ± 10%) that would be expected in healthy, awake adults. Table 1. VAS Scores Conclusions The TetraGraph TM monitor is a hand-held EMG device that produces less painful neurostimulation than the TOF-Watch device in awake, healthy volunteers. The lower discomfort may be due to the larger stimulating area of the TetraGraph TM electrodes that decreases stimulating current density and likely, the pain associated with neurostimulation. The investigators found the monitor easy to use, and required less than a minute for set-up and calibration. The investigators will begin exploring intraoperative applications of the monitor. References 1. Murphy GS, Brull SJ. Residual neuromuscular block: lessons unlearned. Part I: definitions, incidence, and adverse physiologic effects of residual neuromuscular block. Anesth Analg 111(1):120-8 2. Capron F, Fortier LP, Racine S, Donati F. Tactile fade detection with hand or wrist stimulation using train-of-four, double-burst stimulation, 50-hertz tetanus, 100-hertz tetanus, and acceleromyography. Anesth Analg. 2006 May;102(5):1578-84. 3. Renew JR, Brull SJ. The effect of quantitative neuromuscular monitoring on the incidence of residual neuromuscular blockade and clinical outcomes. Curr Anesthesiol Rep. 2016; 6(2): 170-7. Disclosures: Dr. Brull is a member of the Board of Directors of the Anesthesia Patient Safety Foundation (APSF), and Senzime AB (publ.) He has clinical research that is supported by Merck, Inc. (funds distributed to Mayo Clinic), and is a member of the Scientific Advisory Boards for The Doctors Company and ClearLine MD.
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Examining Awake Volunteer Pain Scores and Operator Ease of Use of a Novel Neuromuscular Blockade Monitor
J. Ross Renew, MD; Ilana Logvinov, MSN, RN; Sorin J. Brull, MD, FCARCSI (Hon)
Mayo Clinic, Jacksonville, FL
© 2017 Mayo Foundation for Medical Education and Research
IntroductionPostoperative residual neuromuscular blockade is a significant problem that exposes patients to unnecessary risks (hypoxemia, airway obstruction, unpleasant subjective symptoms, longer recovery, delays in extubation, increased risk of postoperative pulmonary complications and cost).1 The use of peripheral nerve stimulators is common to guide management of neuromuscular blocking agents (NMBAs). However, this technique relies on clinicians to subjectively determine the degree of fade in response to train-of-four (TOF) stimulation. This subjective assessment fails when TOF ratio is between 0.4 and 0.9, because this degree of fade cannot be appreciated by subjective means.
In the normal, unblocked state, the TOF ratio is 1.0; the ratio decreases as an increasing number of receptors (>70%) are blocked by the NMBA, and when 75-80% or receptors are blocked, the ratio approaches 0. Once approximately 90-95% of receptors are blocked, the TOF stimulation produces no evoked responses (TOF count = 0). During recovery of neuromuscular block, the TOF count increases progressively from TOF count = 0 to TOF count 1, then 2, then 3, and ultimately TOF count = 4, at which point the TOF ratio again can be calculated. A sufficient recovery of block is defined as a TOF ratio ≥0.9.2 Quantitative monitors that display, measure and calculate the amplitude of evoked muscle responses are therefore preferred to subjective evaluation, in order to help guide intraoperative management of neuromuscular blockade and accurately demonstrate complete recovery. Unfortunately, many of these quantitative monitoring techniques such as acceleromyography (AMG) and kinemyography (KMG) rely upon freely moving muscles to determine the level of neuromuscular block. Surgical positioning with the patient’s arms tucked to the side can often impede such movements, limit access to the hands, and preclude the use of these motion-based monitors.
Electromyography (EMG) does not depend on freely moving muscles as the sensing electrodes measure electrical activity of the muscle that results from depolarization.3 The authors describe their experience with a new EMG-based neuromuscular monitor, TetraGraphTM (Senzime, Uppsala, Sweden) (Figure 1) and the specially-designed electrodes (Figure 2), and compare the level of discomfort associated with neurostimulation in comparison with an existing monitor, the AMG-based TOF-Watch (Organon, Dublin, Ireland).
ResultsVAS scores obtained with TetraGraphTM were significantly lower than those obtained with TOF-Watch at intensities greater than 30 mA (Table 1). All volunteers completed the trial, and there were no untoward reactions to the stimulations. The TetraGraphTM device interface was intuitive and provided a TOF ratio (100% ± 10%) that would be expected in healthy, awake adults.
ConclusionsThe TetraGraphTM monitor is a hand-held EMG device that produces less painful neurostimulation than the TOF-Watch device in awake, healthy volunteers. The lower discomfort may be due to the larger stimulating area of the TetraGraphTM electrodes that decreases stimulating current density and likely, the pain associated with neurostimulation. The investigators found the monitor easy to use, and required less than a minute for set-up and calibration. The investigators will begin exploring intraoperative applications of the monitor.
References1. Murphy GS, Brull SJ. Residual neuromuscular block: lessons unlearned. Part I: definitions, incidence,
and adverse physiologic effects of residual neuromuscular block. Anesth Analg 111(1):120-8
2. Capron F, Fortier LP, Racine S, Donati F. Tactile fade detection with hand or wrist stimulation using train-of-four, double-burst stimulation, 50-hertz tetanus, 100-hertz tetanus, and acceleromyography. Anesth Analg. 2006 May;102(5):1578-84.
3. Renew JR, Brull SJ. The effect of quantitative neuromuscular monitoring on the incidence of residual neuromuscular blockade and clinical outcomes. Curr Anesthesiol Rep. 2016; 6(2): 170-7.
DisclosuresDr. Brull is a member of the Board of Directors of the Anesthesia Patient Safety Foundation (APSF), and Senzime AB. He has clinical research funded by Merck, Inc. (funds distributed to Mayo Clinic), and is a member of the Scientific Advisory Boards for The Doctors Company and ClearLine MD.
Table 1Visual Analog Scale (VAS) Scores
AmplitudeTOF-Watch TetraGraph
P-valueM SD CI M SD CI
20 mA 1.56 1.25 1.05-1.95 1.52 1.40 0.97-2.07 0.96
30 mA 3.11 1.58 2.72-3.95 2.89 1.93 2.13-3.65 0.35
40 mA 4.25 2.40 3.95-5.85 2.88 1.15 2.39-3.36 <0.0001
50 mA 4.75 2.23 4.54-6.40 4.08 2.38 3.08-5.09 0.04
Overall 3.35 2.24 3.34-4.26 2.80 1.97 2.42-3.19 0.001
M = Mean; SD = standard deviation; CI = Confidence interval with range 5-95%
Figure 1
TetraGraphTM
Figure 2
Specially-Designed Electrodes
MethodsAfter IRB approval, 10 adult volunteers gave oral informed consent to participate in the study. The skin overlying the ulnar nerve on the distal volar forearm was cleansed with alcohol and the TetraGraphTM stimulating electrodes were placed over this area, with the negative stimulating electrode placed distally to the positive stimulating electrode. One sensing electrode was placed on the hypothenar eminence over the belly of the abductor digiti minimi muscle, and the other sensing electrode was placed over the base of the 5th finger over the abductor digiti minimi muscle insertion site, to record the response of the muscle to ulnar nerve stimulation (Figure 3). An anchor visual analog scale (VAS) score (on an 11-point scale where 0=no pain and 10=the most
intense pain ever experienced) was obtained in response to a single twitch stimulation at 30 mA to obtain a reference VAS for the volunteer. TOF stimulation at 20 mA, 30 mA, 40 mA, and 50 mA was delivered in random order, with the volunteer blinded to the intensity. VAS scores were obtained for each of these intensities, with each stimulation performed in triplicate at each of the 4 current amplitudes. The TOF-Watch was then applied to the opposite arm, with stimulating electrodes placed over the ulnar nerve on the distal volar forearm. The accelerometer was taped to the thumb and the preload device was applied, as per manufacturer recommendations. VAS scores were then obtained in triplicate as for TetraGraphTM.
Figure 3
Sensing Electrode Placement
AbstractExamining Awake Volunteer Pain Scores and Operator Ease of Use
of a Novel Neuromuscular Blockade MonitorJ. Ross Renew, MD; Ilana Logvinov, MSN, RN; Sorin J. Brull, MD, FCARCSI (Hon)
Introduction
Postoperative residual neuromuscular blockade is a significant problem that exposes patients to unnecessary risks (hypoxemia, airway obstruction, unpleasant subjective symptoms, longer recovery, delays in extubation, increased risk of postoperative pulmonary complications and cost).1 The use of peripheral nerve stimulators is common to guide management of neuromuscular blocking agents (NMBAs). However, this technique relies on clinicians to subjectively determine the degree of fade in response to train-of-four (TOF) stimulation. This subjective assessment fails when TOF ratio is between 0.4 and 0.9, because this degree of fade cannot be appreciated by subjective means.
In the normal, unblocked state, the TOF ratio is 1.0; the ratio decreases as an increasing number of receptors (>70%) are blocked by the NMBA, and when 75-80% or receptors are blocked, the ratio approaches 0. Once approximately 90-95% of receptors are blocked, the TOF stimulation produces no evoked responses (TOF count = 0). During recovery of neuromuscular block, the TOF count increases progressively from TOF count = 0 to TOF count 1, then 2, then 3, and ultimately TOF count = 4, at which point the TOF ratio again can be calculated. A sufficient recovery of block is defined as a TOF ratio ≥0.9.2 Quantitative monitors that display, measure and calculate the amplitude of evoked muscle responses are therefore preferred to subjective evaluation, in order to help guide intraoperative management of neuromuscular blockade and accurately demonstrate complete recovery. Unfortunately, many of these quantitative monitoring techniques such as acceleromyography (AMG) and kinemyography (KMG) rely upon freely moving muscles to determine the level of neuromuscular block. Surgical positioning with the patient’s arms tucked to the side can often impede such movements, limit access to the hands, and preclude the use of these motion-based monitors.
Electromyography (EMG) does not depend on freely moving muscles as the sensing electrodes measure electrical activity of the muscle that results from depolarization.3 The authors describe their experience with a new EMG-based neuromuscular monitor, TetraGraphTM (Senzime, Uppsala, Sweden) (Figure 1) and the specially-designed electrodes (Figure 2), and compare the level of discomfort associated with neurostimulation in comparison with an existing monitor, the AMG-based TOF-Watch (Organon, Dublin, Ireland).
Methods
After IRB approval, 10 adult volunteers gave oral informed consent to participate in the study. The skin overlying the ulnar nerve on the distal volar forearm was cleansed with alcohol and the TetraGraphTM stimulating electrodes were placed over this area, with the negative stimulating electrode placed distally to the positive stimulating electrode. One sensing electrode was placed on the hypothenar eminence over the belly of the abductor digiti minimi muscle, and the other sensing electrode was placed over the base of the 5th finger over the abductor digiti minimi muscle insertion site, to record the response of the muscle to ulnar nerve stimulation (Figure 3). An anchor visual analog scale (VAS) score (on an 11-point scale where 0=no pain and 10=the most intense pain ever experienced) was obtained in response to a single twitch stimulation at 30 mA to obtain a reference VAS for the volunteer. TOF stimulation at 20 mA, 30 mA, 40 mA, and 50 mA was delivered in random order, with the volunteer blinded to the intensity. VAS scores were obtained for each of these intensities, with each stimulation performed in triplicate at each of the 4 current amplitudes. The TOF-Watch was then applied to the opposite arm, with stimulating electrodes placed over the ulnar nerve on the distal volar forearm. The accelerometer was taped to the thumb and the preload device was applied, as per manufacturer recommendations. VAS scores were then obtained in triplicate as for TetraGraphTM.
Results
VAS scores obtained with TetraGraphTM were significantly lower than those obtained with TOF-Watch at intensities greater than 30 mA (Table 1). All volunteers completed the trial, and there were no untoward reactions to the stimulations. The TetraGraphTM device interface was intuitive and provided a TOF ratio (100% ± 10%) that would be expected in healthy, awake adults.
Table 1. VAS Scores
Conclusions
The TetraGraphTM monitor is a hand-held EMG device that produces less painful neurostimulation than the TOF-Watch device in awake, healthy volunteers. The lower discomfort may be due to the larger stimulating area of the TetraGraphTM electrodes that decreases stimulating current density and likely, the pain associated with neurostimulation. The investigators found the monitor easy to use, and required less than a minute for set-up and calibration. The investigators will begin exploring intraoperative applications of the monitor.
References
1. Murphy GS, Brull SJ. Residual neuromuscular block: lessons unlearned. Part I: definitions, incidence, and adverse physiologic effects of residual neuromuscular block. Anesth Analg 111(1):120-8
2. Capron F, Fortier LP, Racine S, Donati F. Tactile fade detection with hand or wrist stimulation using train-of-four, double-burst stimulation, 50-hertz tetanus, 100-hertz tetanus, and acceleromyography. Anesth Analg. 2006 May;102(5):1578-84.
3. Renew JR, Brull SJ. The effect of quantitative neuromuscular monitoring on the incidence of residual neuromuscular blockade and clinical outcomes. Curr Anesthesiol Rep. 2016; 6(2): 170-7.
Disclosures:
Dr. Brull is a member of the Board of Directors of the Anesthesia Patient Safety Foundation (APSF), and Senzime AB (publ.) He has clinical research that is supported by Merck, Inc. (funds distributed to Mayo Clinic), and is a member of the Scientific Advisory Boards for The Doctors Company and ClearLine MD.
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