Noninvasive optical characterization of muscle blood flow, oxygenation, and metabolism in women with fibromyalgia

Abstract

IntroductionWomen with fibromyalgia (FM) have symptoms of increased muscular fatigue and reduced exercise tolerance, which may be associated with alterations in muscle microcirculation and oxygen metabolism. This study used near-infrared diffuse optical spectroscopies to noninvasively evaluate muscle blood flow, blood oxygenation and oxygen metabolism during leg fatiguing exercise and during arm arterial cuff occlusion in post-menopausal women with and without FM.MethodsFourteen women with FM and twenty-three well-matched healthy controls participated in this study. For the fatiguing exercise protocol, the subject was instructed to perform 6 sets of 12 isometric contractions of knee extensor muscles with intensity steadily increasing from 20 to 70% maximal voluntary isometric contraction (MVIC). For the cuff occlusion protocol, forearm arterial blood flow was occluded via a tourniquet on the upper arm for 3 minutes. Leg or arm muscle hemodynamics, including relative blood flow (rBF), oxy- and deoxy-hemoglobin concentration ([HbO2] and [Hb]), total hemoglobin concentration (THC) and blood oxygen saturation (StO2), were continuously monitored throughout protocols using a custom-built hybrid diffuse optical instrument that combined a commercial near-infrared oximeter for tissue oxygenation measurements and a custom-designed diffuse correlation spectroscopy (DCS) flowmeter for tissue blood flow measurements. Relative oxygen extraction fraction (rOEF) and oxygen consumption rate (rVO2) were calculated from the measured blood flow and oxygenation data. Post-manipulation (fatiguing exercise or cuff occlusion) recovery in muscle hemodynamics was characterized by the recovery half-time, a time interval from the end of manipulation to the time that tissue hemodynamics reached a half-maximal value.ResultsSubjects with FM had similar hemodynamic and metabolic response/recovery patterns as healthy controls during exercise and during arterial occlusion. However, tissue rOEF during exercise in subjects with FM was significantly lower than in healthy controls, and the half-times of oxygenation recovery (Δ[HbO2] and Δ[Hb]) were significantly longer following fatiguing exercise and cuff occlusion.ConclusionsOur results suggest an alteration of muscle oxygen utilization in the FM population. This study demonstrates the potential of using combined diffuse optical spectroscopies (i.e., NIRS/DCS) to comprehensively evaluate tissue oxygen and flow kinetics in skeletal muscle.

Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise

“…Postexercise elevation in muscle hemodynamics is observed to be characteristic for all subjects measured in this study and has been noted by many other studies. 5,6,12,18,35 The 1-min recovery rBF values (118.80 AE 8.20%) observed in this study agree with that of 108% (83% to 139%) measured by DCS immediately postplantar flexion exercise. 12 In addition, the relative increases in SGVP signals measured immediately postexercise (1.13 AE 0.20 ml∕100 ml∕ min at baseline to 5.13 AE 0.32 ml∕100 ml∕ min immediately after exercise) agree well with the reported approximately fivefold increases of SGVP signals postexercise in a study using a similar exercise protocol.…”

“…The overall sampling rate was ∼1 Hz to produce one data point for DCS and five data points for Imagent. Baseline absolute BF was obtained by fitting the slope of the THC increase measured by Imagent during VO, 18,28,35,40 while baseline absolute _ VO 2 was calculated by fitting the slope of the difference between [HbO 2 ] and [Hb] during the first minute of AO. 9,41 Following baseline calibrations, sampling for the hybrid DCS/Imagent was changed to a one-to-one with 1 Hz overall sampling rate for use in the exercise protocol: 600 ms for DCS correlation plus 300 ms for Imagent sampling.…”

“…6,9,32 DCS has been validated against multiple techniques, such as Xenon-computed tomography, arterial-spin-labeled MRI, and laser Doppler, 22,25,33 and has proven successful in making rBF measurements of local muscles in the leg and forearm. 6,9,32,[34][35][36] In some of these studies, DCS has been combined with NIRS to form a hybrid DCS/NIRS instrument for making all-optical measurements of both rBF and StO 2 , which allows for the derivation of the relative change of oxygen consumption rate (r _ VO 2 ). 6,9,22,34 Only recently have occlusion calibrations and gating techniques been applied by our laboratory to allow DCS/NIRS hybrid instruments to simultaneously and continuously measure absolute values of BF, blood oxygenation, and oxygen consumption rate ( _ VO 2 ) in forearm muscles during handgrip exercises.…”

Fibromyalgia: A Critical and Comprehensive Review

“…A major determinant of these discrepancies may be the differential responses of FMS and control subjects to needle insertion trauma, prolonged inactivity or both [492]. However, even non-invasive techniques have yielded conflicting results [504,505].…”

Clinical applications of near-infrared diffuse correlation spectroscopy and tomography for tissue blood flow monitoring and imaging

“…DCS measurements of tissue blood flow changes have been extensively validated against other standards, including power spectral Doppler ultrasound (Yu et al , 2005b), Doppler ultrasound (Buckley et al , 2009; Roche-Labarbe et al , 2010), laser Doppler (Durduran, 2004; Shang et al , 2011a), Xenon computed tomography (Xenon-CT) (Kim et al , 2010), fluorescent microsphere flow measurement (Zhou et al , 2009), and arterial spin labeling magnetic resonance imaging (ASL-MRI) (Yu et al , 2007). In some studies, DCS has been combined with NIRS/DOS in hybrid instruments to simultaneously measure tissue blood flow and oxygenation (Durduran et al , 2004; Yu et al , 2005a; Cheng et al , 2012; Munk et al , 2012; Shang et al , 2012; Gurley et al , 2012), which allows for the derivation of metabolic rate of tissue oxygen consumption.…”