Neuromuscular BlockadeNCT05006807
Comparison Neuromuscular Blockade Monitors
An observational study of Neuromuscular Blockade, run by University of Washington at 1 site in United States.
Trial summary
The overall objective of this research is to evaluate different laboratory-built and commercially available sensors used to measure the effects of neuromuscular blocking drugs on neuromuscular function during surgery, by measuring evoked thumb twitch response to ulnar nerve stimulation (also known as "twitch… Read more about this study
- Who is it for?
- Ages 18 to 100 years
- Conditions the study is for
- Neuromuscular Blockade
- What is being tested?
- Mechanomyograph Twitch Monitor, Stimpod Twitch Monitor and TetraGraph Twitch Monitor
- Type of treatment
- Medical device
- How many people
- 51 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Feb 2022to 1 Dec 2024
- Phase
- Observational
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 100 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Patients 18 years of age or older undergoing anesthesia that requires neuromuscular blocking drugs at University of Washington Medical Center.
Who may be able to join
- 18 years of age or greater
- Undergoing anesthesia that requires neuromuscular blocking drugs
Who cannot join
- Less than 18 years of age
- Undergoing anesthesia that does not require neuromuscular blocking drugs
- Undergoing a procedure in which access to one or both arms is limited
- Anatomical abnormalities of the hands or arms that preclude twitch monitoring with ulnar nerve stimulation and evoked thumb twitch response
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Washington Medical Center
Seattle, Washington, 98195
About this study
Official title: Comparative Assessment of Neuromuscular Blockade Monitors
The overall objective of this research is to evaluate different laboratory-built and commercially available sensors used to measure the effects of neuromuscular blocking drugs on neuromuscular function during surgery, by measuring evoked thumb twitch response to ulnar nerve stimulation (also known as "twitch monitoring"). The specific aim is to compare mechanomyography, which is the "gold standard" laboratory measurement to assess neuromuscular blockade, to the sensors used in commercially available neuromuscular blockade monitors, such as acceleromyography and electromyography. The study endpoints are the train-of-four count (TOFC), the ratio of the height of the 4th twitch to the height of the 1st twitch (train-of-four ratio, TOFR), and the post tetanic count (PTC). The mechanomyography devices have been constructed in our laboratory and are not commercially available.
Read the detailed description
Twitch monitoring will be performed as described below for each device:
Stimpod NMS 450 or other related Stimpod device (Xavant Technology, Pretoria, South Africa)--acceleromyography and/or electromyography. Movement of the thumb and hand will not be restricted and no artificial preload will be used. Electrodes (3M Red Dot, 3M Healthcare, St. Paul, MN, USA) will be applied over the ulnar nerve at the wrist for acceleromyography. The Stimpod acceleromyography sensor will be attached to the distal phalanx of the thumb using the supplied plastic circumferential band, reinforced with tape if necessary. The Stimpod electromyography printed electrode array will be applied as described in the manufacturer's instructions for use.
TwitchView Monitor (Blink Device Company, Seattle, WA, USA)--electromyography. The TwitchView electromyography printed electrode array will be applied as described in the manufacturer's instructions for use.
TetraGraph (Senzime, Sweden)--electromyography. The TetraGraph electromyography printed electrode array will be applied as described in the manufacturer's instructions for use.
Nihon Kohden (Japan)--electromyography. The Nihon Kohden printed electromyography electrode array will be applied as described in the manufacturer's instructions for use.
Mechanomyography. The mechanomyography monitors were built in our laboratory and consists of a force transducer, signal amplifier and analogue to digital converter held in a 3D printed wrist and hand immobilizer, or other hand immobilizer rig. The mechanomyography force transducer response is linear with precision to 5g and accuracy to 25g for measurements examined from 0 to 5kg with sensitivity to 10g within that range. A preload of 200-300g will applied to the thumb prior to data collection. Custom software using the LabVIEW package (National Instruments, Austin, Texas) was developed for data acquisition, analysis of the voltage response after the train-of-four stimulus and for counting the twitches.
General experimental conditions. The amplitude of the train of four stimulus will be set at 60 mA in all cases. Skin prep with alcohol wipes will be performed prior to attaching any electrodes. Temperature homeostasis will be maintained in all patients through the use of active warming. Normocarbia will be maintained as defined by end tidal CO2 between approximately 32 and 40 mmHg. The anesthesia technique including the choice of anesthetic and neuromuscular blocking agents will be at the discretion of the anesthesia care team and may include propofol, opioids (mainly fentanyl and hydromorphone), sevoflurane, isoflurane, rocuronium and vecuronium. Data collection will be customized in each patient depending upon the availability of upper limbs for monitoring. Acceleromyography and mechanomyography cannot be tested on the same arm simultaneously because the mechanomyography restricts movement of the thumb. The electromyography electrode array does not interfere with simultaneously measuring either acceleromyography or mechanomyography. Subjective twitch count can be made on the same hand as the acceleromyography or electromyography measurement, but not on the same hand as mechanomyography since the plastic frame or other rig of the mechanomyography precludes manual palpation of thumb movement. Train-of- four count will be measured by palpation (when possible) and then by one or more of the twitch monitors (i.e. two measurements were taken within the span of about 2 minutes) approximately every 5 minutes from induction of anesthesia until just before emergence from anesthesia. Measurements will not be made for 10 minutes following administration of neuromuscular blocking drugs or reversal agents in order to avoid periods when the extent of neuromuscular blockade was changing very rapidly. When measurements were made on both arms, the train of four twitch stimulus will be administered in each arm within about 2 minutes. Not all twitch monitoring devices we be evaluated in each patient. The choice of devices to be evaluated in each patient will be made primarily on the basis of the availability of arms for monitoring and the availability of monitoring devices.
- Conditions
- Neuromuscular Blockade
- Being tested
- Mechanomyograph Twitch Monitor, Stimpod Twitch Monitor, TetraGraph Twitch Monitor, TwitchView Twitch Monitor, Nihon Kohden Twitch Monitor
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Mechanomyograph Twitch MonitorDevice
Measurement of train-of-four count and ratio and post tetanic count
Stimpod Twitch MonitorDevice
Measurement of train-of-four count and ratio and post tetanic count
TetraGraph Twitch MonitorDevice
Measurement of train-of-four count and ratio and post titanic count
TwitchView Twitch MonitorDevice
Measurement of train-of-four count and ratio and post tetanic count
Nihon Kohden Twitch MonitorDevice
Measurement of train-of-four count and ratio and post tetanic count
Palpation of twitch countOther
The train-of-four count is determined by manual palpation of the evoked twitch response
| Study group | Role | What they receive |
|---|---|---|
| Twitch Monitoring | Patients undergoing surgery with general anesthesia requiring neuromuscular blockade. Receives: Device: Mechanomyograph Twitch Monitor; Device: Stimpod Twitch Monitor; Device: TetraGraph Twitch Monitor; Device: TwitchView Twitch Monitor; Device: Nihon Kohden Twitch Monitor; Other: Palpation of twitch count |
What is being measured
The primary outcome is the main question the study is designed to answer.
Train-of-four Ratio
Determine evoked thumb twitch response to ulnar nerve train-of-four stimulation then determine the ratio of the amplitude of the fourth twitch divided by the first twitch, referred to as the train-of-four ratio. The train-of-four ratio is expected to be 1.0 in the absence of neuromuscular blocking drugs. The range of possible train-of-four ratios is 0-1.6. Results that deviate from a train-of-four ratio of 1.0 represent inaccuracy of the measurement.
Measured: Procedure (from the induction of anesthesia until emergence of anesthesia)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Aug 2021
- Study start1 Feb 2022
- Primary completion1 Dec 2024
- Study completion1 Dec 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Neuromuscular BlockadeStudies of the same condition, open and under way.
- More trials run by University of WashingtonThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case only
- Time perspective
- Prospective
- Enrolment
- 51 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Washington
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, T. Andrew Bowdle, University of Washington
- Investigators
- T. Andrew Bowdle, MD, PhD, Principal investigator, University of Washington
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05006807
- Sponsor's protocol ID
- STUDY00001561
- Status last verified
- Dec 2024
- First submitted
- 10 Aug 2021
- Last updated
- 8 Jul 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Wedemeyer Z, Bowdle A, Jelacic S, Silliman W, Michaelsen KE. The effect of excessive noise rejection, noise filtering and twitch threshold on mechanomyograph twitch measurements. Anaesth Crit Care Pain Med. 2026 May;45(3):101780. doi: 10.1016/j.accpm.2026.101780. Epub 2026 Mar 3.
PubMed 41786028Wedemeyer Z, Jelacic S, Michaelsen K, Silliman W, Togashi K, Bowdle A. Comparative performance of stimpod electromyography with mechanomyography for quantitative neuromuscular blockade monitoring. J Clin Monit Comput. 2024 Feb;38(1):205-212. doi: 10.1007/s10877-023-01087-1. Epub 2023 Oct 13.
PubMed 37831378
Study at a glance
From the registry record, last updated by the sponsor on 8 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparative Assessment of Neuromuscular Blockade Monitors
- ClinicalTrials.gov ID
- NCT05006807
- Acronym / sponsor ID
- STUDY00001561
- Conditions
- Neuromuscular Blockade
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 51 participants (actual)
- Lead sponsor
- University of WashingtonUniversity, hospital or other
- Study start
- 1 Feb 2022 (actual)
- Primary completion
- 1 Dec 2024 (actual)
- Study completion
- 1 Dec 2024 (actual)
- First posted
- 16 Aug 2021 (actual)
- Results
- Posted 8 Jul 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The overall objective of this research is to evaluate different laboratory-built and commercially available sensors used to measure the effects of neuromuscular blocking drugs on neuromuscular function during surgery, by measuring evoked thumb twitch response to ulnar nerve stimulation (also known as "twitch monitoring"). The specific aim is to compare mechanomyography, which is the "gold standard" laboratory measurement to assess neuromuscular blockade, to the sensors used in commercially available neuromuscular blockade monitors, such as acceleromyography and electromyography. The study endpoints are the train-of-four count (TOFC), the ratio of the height of the 4th twitch to the height of the 1st twitch (train-of-four ratio, TOFR), and the post tetanic count (PTC). The mechanomyography devices have been constructed in our laboratory and are not commercially available.
Detailed description
Twitch monitoring will be performed as described below for each device:
Stimpod NMS 450 or other related Stimpod device (Xavant Technology, Pretoria, South Africa)--acceleromyography and/or electromyography. Movement of the thumb and hand will not be restricted and no artificial preload will be used. Electrodes (3M Red Dot, 3M Healthcare, St. Paul, MN, USA) will be applied over the ulnar nerve at the wrist for acceleromyography. The Stimpod acceleromyography sensor will be attached to the distal phalanx of the thumb using the supplied plastic circumferential band, reinforced with tape if necessary. The Stimpod electromyography printed electrode array will be applied as described in the manufacturer's instructions for use.
TwitchView Monitor (Blink Device Company, Seattle, WA, USA)--electromyography. The TwitchView electromyography printed electrode array will be applied as described in the manufacturer's instructions for use.
TetraGraph (Senzime, Sweden)--electromyography. The TetraGraph electromyography printed electrode array will be applied as described in the manufacturer's instructions for use.
Nihon Kohden (Japan)--electromyography. The Nihon Kohden printed electromyography electrode array will be applied as described in the manufacturer's instructions for use.
Mechanomyography. The mechanomyography monitors were built in our laboratory and consists of a force transducer, signal amplifier and analogue to digital converter held in a 3D printed wrist and hand immobilizer, or other hand immobilizer rig. The mechanomyography force transducer response is linear with precision to 5g and accuracy to 25g for measurements examined from 0 to 5kg with sensitivity to 10g within that range. A preload of 200-300g will applied to the thumb prior to data collection. Custom software using the LabVIEW package (National Instruments, Austin, Texas) was developed for data acquisition, analysis of the voltage response after the train-of-four stimulus and for counting the twitches.
General experimental conditions. The amplitude of the train of four stimulus will be set at 60 mA in all cases. Skin prep with alcohol wipes will be performed prior to attaching any electrodes. Temperature homeostasis will be maintained in all patients through the use of active warming. Normocarbia will be maintained as defined by end tidal CO2 between approximately 32 and 40 mmHg. The anesthesia technique including the choice of anesthetic and neuromuscular blocking agents will be at the discretion of the anesthesia care team and may include propofol, opioids (mainly fentanyl and hydromorphone), sevoflurane, isoflurane, rocuronium and vecuronium. Data collection will be customized in each patient depending upon the availability of upper limbs for monitoring. Acceleromyography and mechanomyography cannot be tested on the same arm simultaneously because the mechanomyography restricts movement of the thumb. The electromyography electrode array does not interfere with simultaneously measuring either acceleromyography or mechanomyography. Subjective twitch count can be made on the same hand as the acceleromyography or electromyography measurement, but not on the same hand as mechanomyography since the plastic frame or other rig of the mechanomyography precludes manual palpation of thumb movement. Train-of- four count will be measured by palpation (when possible) and then by one or more of the twitch monitors (i.e. two measurements were taken within the span of about 2 minutes) approximately every 5 minutes from induction of anesthesia until just before emergence from anesthesia. Measurements will not be made for 10 minutes following administration of neuromuscular blocking drugs or reversal agents in order to avoid periods when the extent of neuromuscular blockade was changing very rapidly. When measurements were made on both arms, the train of four twitch stimulus will be administered in each arm within about 2 minutes. Not all twitch monitoring devices we be evaluated in each patient. The choice of devices to be evaluated in each patient will be made primarily on the basis of the availability of arms for monitoring and the availability of monitoring devices.
Study design
- Observational model
- Case only
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Twitch Monitoring | – | Device: Mechanomyograph Twitch Monitor, Device: Stimpod Twitch Monitor, Device: TetraGraph Twitch Monitor, Device: TwitchView Twitch Monitor, Device: Nihon Kohden Twitch Monitor, Other: Palpation of twitch countPatients undergoing surgery with general anesthesia requiring neuromuscular blockade. |
Who may qualify
- Ages
- 18 to 100 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Patients 18 years of age or older undergoing anesthesia that requires neuromuscular blocking drugs at University of Washington Medical Center.
Key inclusion criteria (2 listed)
- 18 years of age or greater
- Undergoing anesthesia that requires neuromuscular blocking drugs
Key exclusion criteria (4 listed)
- Less than 18 years of age
- Undergoing anesthesia that does not require neuromuscular blocking drugs
- Undergoing a procedure in which access to one or both arms is limited
- Anatomical abnormalities of the hands or arms that preclude twitch monitoring with ulnar nerve stimulation and evoked thumb twitch response
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Mechanomyograph Twitch MonitorMeasurement of train-of-four count and ratio and post tetanic count | Device | Twitch Monitoring |
| Stimpod Twitch MonitorMeasurement of train-of-four count and ratio and post tetanic count | Device | Twitch Monitoring |
| TetraGraph Twitch MonitorMeasurement of train-of-four count and ratio and post titanic count | Device | Twitch Monitoring |
| TwitchView Twitch MonitorMeasurement of train-of-four count and ratio and post tetanic count | Device | Twitch Monitoring |
| Nihon Kohden Twitch MonitorMeasurement of train-of-four count and ratio and post tetanic count | Device | Twitch Monitoring |
| Palpation of twitch countThe train-of-four count is determined by manual palpation of the evoked twitch response | Other | Twitch Monitoring |
Primary outcome
Train-of-four Ratio
Time frame: Procedure (from the induction of anesthesia until emergence of anesthesia)
Determine evoked thumb twitch response to ulnar nerve train-of-four stimulation then determine the ratio of the amplitude of the fourth twitch divided by the first twitch, referred to as the train-of-four ratio. The train-of-four ratio is expected to be 1.0 in the absence of neuromuscular blocking drugs. The range of possible train-of-four ratios is 0-1.6. Results that deviate from a train-of-four ratio of 1.0 represent inaccuracy of the measurement.
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 Jul 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 41786028Wedemeyer Z, Bowdle A, Jelacic S, Silliman W, Michaelsen KE. The effect of excessive noise rejection, noise filtering and twitch threshold on mechanomyograph twitch measurements. Anaesth Crit Care Pain Med. 2026 May;45(3):101780. doi: 10.1016/j.accpm.2026.101780. Epub 2026 Mar 3.
- Derived from this study: PubMed 37831378Wedemeyer Z, Jelacic S, Michaelsen K, Silliman W, Togashi K, Bowdle A. Comparative performance of stimpod electromyography with mechanomyography for quantitative neuromuscular blockade monitoring. J Clin Monit Comput. 2024 Feb;38(1):205-212. doi: 10.1007/s10877-023-01087-1. Epub 2023 Oct 13.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
T. Andrew Bowdle, MD, PhD principal investigator
University of Washington
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Neuromuscular Blockade, run by University of Washington at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 8 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 8 Jul 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Train-of-four Ratio (time frame: Procedure (from the induction of anesthesia until emergence of anesthesia)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05006807, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 8 Jul 2026.