Format

Send to

Choose Destination
Respir Physiol Neurobiol. 2017 Jan;235:18-26. doi: 10.1016/j.resp.2016.09.008. Epub 2016 Sep 19.

Reproducibility of NIRS assessment of muscle oxidative capacity in smokers with and without COPD.

Author information

1
Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA. Electronic address: aadami@labiomed.org.
2
Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA. Electronic address: rcao@labiomed.org.
3
Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA. Electronic address: porszasz@ucla.edu.
4
Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA. Electronic address: casaburi@ucla.edu.
5
Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA. Electronic address: hrossiter@ucla.edu.

Abstract

Low muscle oxidative capacity contributes to exercise intolerance in chronic obstructive pulmonary disease (COPD). Near-infrared spectroscopy (NIRS) allows non-invasive determination of the muscle oxygen consumption (mV̇O2) recovery rate constant (k), which is proportional to oxidative capacity assuming two conditions are met: 1) exercise intensity is sufficient to fully-activate mitochondrial oxidative enzymes; 2) sufficient O2 availability. We aimed to determine reproducibility (coefficient of variation, CV; intraclass correlation coefficient, ICC) of NIRS k assessment in the gastrocnemius of 64 participants with (FEV1 64±23%predicted) or without COPD (FEV1 98±14%predicted). 10-15s dynamic contractions preceded 6min of intermittent arterial occlusions (5-10s each, ∼250mmHg) for k measurement. k was lower (P<0.05) in COPD (1.43±0.4min-1; CV=9.8±5.9%, ICC=0.88) than controls (1.74±0.69min-1; CV=9.9±8.4%; ICC=0.93). Poor k reproducibility was more common when post-contraction mV̇O2 and deoxygenation were low, suggesting insufficient exercise intensity for mitochondrial activation and/or the NIRS signal contained little light reflected from active muscle. The NIRS assessment was well tolerated and reproducible for muscle dysfunction evaluation in COPD.

KEYWORDS:

Exercise intolerance; Kinetics; Mitochondria; Oxygen consumption; Quality-control; Skeletal muscle

PMID:
27659351
PMCID:
PMC5136338
DOI:
10.1016/j.resp.2016.09.008
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center