Back to Search
Start Over
Continuous measurements of respiratory muscle blood flow and oxygen consumption using noninvasive frequency-domain near-infrared spectroscopy and diffuse correlation spectroscopy.
- Source :
- Journal of Applied Physiology; Aug2024, Vol. 137 Issue 2, p382-393, 12p
- Publication Year :
- 2024
-
Abstract
- Prior studies of muscle blood flow and muscle-specific oxygen consumption have required invasive injection of dye and magnetic resonance imaging, respectively. Such measures have limited utility for continuous monitoring of the respiratory muscles. Frequency-domain near-infrared spectroscopy and diffuse correlation spectroscopy (FD-NIRS & DCS) can provide continuous surrogate measures of blood flow index (BF<subscript>i</subscript>) and metabolic rate of oxygen consumption (MRO<subscript>2</subscript>). This study aimed to validate sternocleidomastoid FD-NIRS & DCS outcomes against electromyography (EMG) and mouth pressure (Pm) during incremental inspiratory threshold loading (ITL). Six female and six male healthy adults (means ± SD; 30 ± 7 yr, maximum inspiratory pressure 118 ± 61 cmH<subscript>2</subscript>O) performed incremental ITL starting at low loads (8 ± 2 cmH<subscript>2</subscript>O) followed by 50-g increments every 2 min until task failure. FD-NIRS & DCS continuously measured sternocleidomastoid oxygenated and deoxygenated hemoglobin + myoglobin (oxy/deoxy[Hb + Mb]), tissue saturation of oxygen (StO<subscript>2</subscript>), BF<subscript>i</subscript>, and MRO<subscript>2</subscript>. Ventilatory parameters including inspiratory Pm were also evaluated. Pm increased during incremental ITL (P < 0.05), reaching −47[−74 to −34] cmH<subscript>2</subscript>O (median [IQR: 25%–75%]) at task failure. Ventilatory parameters were constant throughout ITL (all P > 0.05). Sternocleidomastoid BF<subscript>i</subscript> and MRO<subscript>2</subscript> increased from the start of the ITL (both P < 0.05). Deoxy[Hb + Mb] increased close to task failure, concomitantly with a constant increase in MRO<subscript>2</subscript>, and decreased StO<subscript>2</subscript>. Sternocleidomastoid deoxy[Hb + Mb], BF<subscript>i</subscript>, StO<subscript>2</subscript>, and MRO<subscript>2</subscript> obtained during ITL via FD-NIRS & DCS correlated with sternocleidomastoid EMG (all P < 0.05). In healthy adults, FD-NIRS & DCS can provide continuous surrogate measures of respiratory BF<subscript>i</subscript> and MRO<subscript>2</subscript>. Increasing sternocleidomastoid oxygen consumption near task failure was associated with increased oxygen extraction and reduced tissue saturation. NEW & NOTEWORTHY: This study introduces a novel approach, frequency-domain near-infrared spectroscopy and diffuse correlation spectroscopy (FD-NIRS & DCS), for noninvasive continuous monitoring of respiratory muscle blood flow and metabolic rate of oxygen consumption. Unlike prior methods involving invasive dye injection and magnetic resonance imaging, FD-NIRS & DCS offers the advantage of continuous measurement without the need for invasive procedures. It holds promise for advancing muscle physiology understanding and opens avenues for real-time monitoring of respiratory muscles. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 87507587
- Volume :
- 137
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Journal of Applied Physiology
- Publication Type :
- Academic Journal
- Accession number :
- 179461210
- Full Text :
- https://doi.org/10.1152/japplphysiol.00871.2023