An interventional study of Magnetic Femoral Nerve Stimulation in Critical Illness and ICU-acquired Weakness, sponsored by Daniel Langer. Not yet recruiting. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-23.
Sponsored by Daniel Langer · Not applicable, Interventional, and Other
Intensive care unit-acquired weakness (ICU-AW) is a common complication of critical illness and can negatively affect recovery and long-term physical functioning. Early and reliable assessment of muscle strength is essential for detecting muscle weakness and monitoring changes during an intensive care unit (ICU) stay. However, conventional strength assessments, such as manual muscle testing, require voluntary muscle contractions, making them unsuitable for patients who are not yet cooperative and limiting the possibility of assessing muscle strength during the early stages of critical illness. Magnetic femoral nerve stimulation offers an alternative, non-volitional approach to assessing quadriceps muscle strength. Nevertheless, the reliability and validity of this technique in critically ill patients remain insufficiently established.
This prospective methodological study aims to investigate the reliability and convergent validity of quadriceps twitch force measurements obtained using magnetic femoral nerve stimulation in critically ill patients.
A total of 33 cooperative adult patients admitted to medical or surgical ICUs will be included. Participants will undergo repeated quadriceps twitch force assessments over two consecutive days, performed by two assessors. Measurements will be conducted using a custom-developed frame designed to facilitate standardized quadriceps strength assessment at the bedside. Both single and paired magnetic stimulation techniques will be evaluated.
The primary outcome is the intra-rater reliability of paired twitch force measurements. Secondary outcomes include the inter-rater reliability of paired twitch force measurements, the intra-rater and inter-rater reliability of single twitch force measurements, and the convergent validity of twitch force measurements assessed through their association with maximal voluntary contraction force and potentiated twitch force. Reliability and agreement will be evaluated using intraclass correlation coefficients and complementary measurement error analyses.
Establishing these measurement properties could support objective, non-volitional muscle strength assessment in critically ill patients, including those unable to participate in conventional strength testing. This could facilitate early baseline strength assessment, longitudinal monitoring of muscle recovery, and the evaluation of interventions aimed at preventing or treating ICU-AW..
1,923 studies on the registry are indexed under Critical Illness; 465 are open to participants now.
This study's planned enrollment of 33 is below the median of 90 across 1,003 interventional studies indexed under Critical Illness.
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Exclusion Criteria:
Medical instability A: Cardiorespiratory instability
Contraindications to magnetic stimulation A: Implanted metal or electronic devices, including
All participants will undergo quadriceps muscle strength assessments over two consecutive days, following the same standardized measurement sequence. On the first day, the first assessor will perform single and paired twitch force measurements using magnetic femoral nerve stimulation, alongside maximal voluntary contraction and potentiated twitch force assessments. On the second day, single and paired twitch force measurements will be repeated by the first assessor in the morning and by a second assessor in the afternoon to evaluate intra-rater and inter-rater reliability.
Diagnostic Test: Magnetic Femoral Nerve Stimulation
Participants will be positioned prone in their hospital bed, with the knee flexed at approximately 90° using a dedicated measurement setup. A magnetic stimulation coil will be placed over the femoral nerve to elicit involuntary quadriceps muscle contractions. The resulting twitch force will be measured using a strain gauge dynamometer attached at the ankle. Stimulation intensity will be progressively increased to establish supramaximal stimulation, after which both single and paired magnetic stimuli will be applied to assess quadriceps twitch force.
Intra-rater reliability of paired quadriceps twitch force measurements
Intra-rater reliability of paired quadriceps twitch force measurements will be assessed using the intraclass correlation coefficient (ICC) with 95% confidence intervals, comparing measurements performed by the same assessor on two consecutive days. Measurement error and agreement will additionally be evaluated using the standard error of measurement (SEM), minimal detectable change (MDC95), and Bland-Altman analysis.
Time frame: Day 1 and Day 2 (two consecutive days)
Inter-rater reliability of paired quadriceps twitch force measurements
Inter-rater reliability of paired quadriceps twitch force measurements will be assessed using the intraclass correlation coefficient (ICC) with 95% confidence intervals, comparing measurements performed by two different assessors on the second day. Measurement error and agreement will additionally be evaluated using SEM, MDC95, and Bland-Altman analysis.
Time frame: Day 2 (morning and afternoon)
Intra-rater reliability of single quadriceps twitch force measurements
Intra-rater reliability of single quadriceps twitch force measurements will be assessed using the intraclass correlation coefficient (ICC) with 95% confidence intervals, comparing measurements performed by the same assessor on two consecutive days. Measurement error and agreement will additionally be evaluated using SEM, MDC95, and Bland-Altman analysis.
Time frame: Day 1 and Day 2 (two consecutive days)
Inter-rater reliability of single quadriceps twitch force measurements
Inter-rater reliability of single quadriceps twitch force measurements will be assessed using the intraclass correlation coefficient (ICC) with 95% confidence intervals, comparing measurements performed by two different assessors on the second day. Measurement error and agreement will additionally be evaluated using SEM, MDC95, and Bland-Altman analysis.
Time frame: Day 2 (morning and afternoon)
Convergent validity of single twitch force with maximal voluntary contraction
Convergent validity will be assessed by examining the association between single quadriceps twitch force measurements obtained using magnetic femoral nerve stimulation and maximal voluntary contraction (MVC) force, using Pearson's correlation coefficient (r).
Time frame: Day 1
Convergent validity of paired twitch force with maximal voluntary contraction
Convergent validity will be assessed by examining the association between paired quadriceps twitch force measurements obtained using magnetic femoral nerve stimulation and maximal voluntary contraction (MVC) force, using Pearson's correlation coefficient (r).
Time frame: Day 1
Convergent validity of single twitch force with potentiated twitch force
Convergent validity will be assessed by examining the association between single quadriceps twitch force measurements obtained using magnetic femoral nerve stimulation and potentiated twitch force, using Pearson's correlation coefficient (r).
Time frame: Day 1
Convergent validity of paired twitch force with potentiated twitch force
Convergent validity will be assessed by examining the association between paired quadriceps twitch force measurements obtained using magnetic femoral nerve stimulation and potentiated twitch force, using Pearson's correlation coefficient (r).
Time frame: Day 1
No study locations are listed for this record.
Plan to share: No
No publications or documents are linked to this record.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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