Healthy Adult Participants
Conditions
Keywords
Blood Circulation, Neuromuscular Electrical Stimulation, Muscle Contraction, Hemodynamics
Brief summary
The primary objective of this study is to explore the application of the Firefly® device for delivering NMES to anatomically defined regions of the upper limb and to observe associated physiological changes. Specifically, the study will assess alterations in arterial and venous blood flow, as well as local muscle oxygen saturation, as potential indicators of muscle perfusion during NMES.
Detailed description
Participants will undergo NMES using the Firefly® device, applied to two predefined regions of the upper limb: one targeting the anterior arm nerve bundle (a collective term referring to motor and sensory nerves within the anterior and medial compartments of the upper arm, including the musculocutaneous and adjacent (median, medial cutaneous, ulnar and radial) nerves, and the other targeting the median nerve in the proximal forearm. Vascular responses will be assessed at two sites, the brachial artery and axillary vein, using Doppler ultrasound. For each nerve-vascular site pairing, NMES will alternate between stimulation OFF and ON conditions (10 OFF and 10 ON cycles), comprising one stimulation block of approximately 20 minutes. Each participant will complete four stimulation blocks in total. During both ON and OFF phases, blood flow volume and haemodynamic parameters, including peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI), will be recorded. Additionally, local muscle oxygen saturation (SmO₂) will be continuously monitored using functional near-infrared spectroscopy (fNIRS) to assess tissue-level physiological changes. The total study participation time per individual is approximately 2 hours.
Interventions
DEVICEFirefly NMES device
Firefly NMES device applied to the upper limb during a single-visit exploratory pysiological study
Sponsors
Kieron.Day
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
This is a single-centre, within-subject exploratory study designed to evaluate the physiological effects of NMES applied to the upper limb using the Firefly® device. A repeated-measures design will be used to compare physiological parameters under alternating stimulation OFF and ON conditions.
Eligibility
Sex/Gender
ALL
Age
18 Years to 45 Years
Healthy volunteers
No
Inclusion criteria
* Aged 18 to 45 years (inclusive) * No known history of vascular or neurological conditions affecting the upper extremities * Able to read, understand, and communicate in English to ensure informed consent and safe participation in the study
Exclusion criteria
* Presence of any condition that contraindicates the use of neuromuscular electrical stimulation (e.g., implanted pacemaker, epilepsy) * Current or recent injury to the upper limbs that may interfere with stimulation or measurement * Anatomical variations in the brachial artery or axillary vein, specifically vascular branching outside expected anatomical locations, as identified by ultrasound, which may impair accurate blood flow measurement or device placement * Currently participating in another interventional or physiological research study or having done so within the past 30 days. * Currently pregnant
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in upper-limb blood flow volume during NMES (ON vs OFF) | During single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles | Within-subject change in upper-limb blood flow volume (mL/min) measured using Doppler ultrasound during neuromuscular electrical stimulation (NMES) delivered via the Firefly device, comparing stimulation ON versus OFF conditions. Measurements will be collected across repeated stimulation cycles at predefined upper-limb stimulation zones and vascular assessment sites. |
| Change in upper-limb peak systolic velocity during NMES (ON vs OFF) | During a single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles. | Within-subject change in upper-limb peak systolic velocity (PSV; cm/s) measured using Doppler ultrasound during NMES delivered via the Firefly device, comparing stimulation ON versus OFF conditions across repeated stimulation cycles at predefined upper-limb stimulation zones and vascular assessment sites. |
| Change in upper-limb end-diastolic velocity during NMES (ON vs OFF) | During a single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles. | Within-subject change in upper-limb end-diastolic velocity (EDV; cm/s) measured using Doppler ultrasound during NMES delivered via the Firefly device, comparing stimulation ON versus OFF conditions across repeated stimulation cycles at predefined upper-limb stimulation zones and vascular assessment sites. |
| Change in upper-limb resistive index during NMES (ON vs OFF) | During a single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles. | Within-subject change in upper-limb resistive index (RI; unitless ratio) derived from Doppler ultrasound measurements during NMES delivered via the Firefly device, comparing stimulation ON versus OFF conditions across repeated stimulation cycles at predefined upper-limb stimulation zones and vascular assessment sites. |
| Change in upper-limb muscle oxygen saturation during NMES (ON vs OFF) | During a single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles. | Within-subject change in upper-limb muscle oxygen saturation (SmO₂; %) measured continuously using functional near-infrared spectroscopy (fNIRS) during NMES delivered via the Firefly device, comparing stimulation ON versus OFF conditions across repeated stimulation cycles at predefined upper-limb stimulation zones and assessment sites. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Incidence of adverse events and device-related effects | During single study visit (approximately 2 hours) | Number and type of adverse events (AEs), serious adverse events (SAEs), adverse device effects (ADEs), serious adverse device effects (SADEs), and device deficiencies observed during study participation. |
Countries
United Kingdom
Outcome results
None listed