Evaluation of muscle oxygenation by near-infrared spectroscopy in patients with Becker muscular dystrophy

Evolution of Muscular Oxygenation during a Walking Test in Preterm Children

OBJECTIVE

To explore measures of peripheral muscular oxygenation, coupled to gait characteristics, between preterm and full-term children during a 6-minute walking test (6MWT).

STUDY DESIGN

Prepubescent children performed a 6MWT. During the test, changes in muscular oxyhemoglobin, deoxyhemoglobin, and total hemoglobin were measured with Near-infrared spectroscopy technology, positioned on subjects' calves. Gait variables were monitored with the OptoGait system.

RESULTS

Forty-five children (33 full-term children and 12 preterm children, mean age, 4.9 ± 0.7 and 4.6 ± 0.9 years, respectively) participated in this study. Statistical analysis highlighted a decreased walking performance for preterm children, with significantly lower walking distance (P < .05) than children born full-term (405.1 ± 91.8 m vs 461.0 ± 73.3 m respectively; -9%). A concomitant increase of oxygen extraction (over the time course of Variation of desoxyhemoglobin) was observed from the third minute of the test (P < .05). No statistically significant difference was found for other near-infrared spectroscopy measures. Finally, the analysis of gait variables highlighted a group effect for walking speed (P < .05) and stride length (P < .01).

CONCLUSIONS

Premature children showed decreased walking performance and greater change in peripheral muscular oxygen extraction, associated with slower walking speed and stride length. This may point to a muscular maladjustment and reduced functional capacities for children born preterm. These phenomena could be responsible for greater muscular fatigue.

Intramuscular blood flow in Duchenne and Becker Muscular Dystrophy: Quantitative power Doppler sonography relates to disease severity

OBJECTIVE

Absent or truncated dystrophin in Duchenne (DMD) and Becker (BMD) muscular dystrophies results in impaired vasodilatory pathways and exercise induced muscle ischemia. Here, we used power Doppler sonography to quantify changes in intramuscular blood flow immediately following exercise in boys with D/BMD.

METHOD

We quantified changes in intramuscular blood flow following exercise using power Doppler sonography in 14 boys with D/BMD and compared changes in muscle blood flow to disease severity and to historic controls.

RESULT

Post exercise blood flow change in the anterior forearm muscles is lower in (1) DMD (median 0.25%; range -0.47 to 2.19%) than BMD (2.46%; 2.02-3.38%, p < 0.05) and historical controls (6.59%; 2.16-12.40%, p < 0.01); (2) in non-ambulatory (0.04%; -0.47 to 0.10%) than ambulatory DMD boys (0.71%; 0.07-2.19%, p < 0.05); and (3) in muscle with higher echointensity (r_s = -0.7253, p = 0.005). The tibialis anterior showed similar findings. We estimate that a single sample clinical trial would require 19 subjects to detect a doubling of blood flow to the anterior forearm after the intervention.

CONCLUSION

Post-exercise blood flow is reduced in D/BMD and relates to disease severity.

SIGNIFICANCE

Our protocol for quantifying post-exercise intramuscular blood flow is feasible for clinical trials in D/BMD.

Comparative NMR and NIRS analysis of oxygen-dependent metabolism in exercising finger flexor muscles

Muscle contraction requires the physiology to adapt rapidly to meet the surge in energy demand. To investigate the shift in metabolic control, especially between oxygen and metabolism, researchers often depend on near-infrared spectroscopy (NIRS) to measure noninvasively the tissue O₂ Because NIRS detects the overlapping myoglobin (Mb) and hemoglobin (Hb) signals in muscle, interpreting the data as an index of cellular or vascular O₂ requires deconvoluting the relative contribution. Currently, many in the NIRS field ascribe the signal to Hb. In contrast, ¹H NMR has only detected the Mb signal in contracting muscle, and comparative NIRS and NMR experiments indicate a predominant Mb contribution. The present study has examined the question of the NIRS signal origin by measuring simultaneously the ¹H NMR, ³¹P NMR, and NIRS signals in finger flexor muscles during the transition from rest to contraction, recovery, ischemia, and reperfusion. The experiment results confirm a predominant Mb contribution to the NIRS signal from muscle. Given the NMR and NIRS corroborated changes in the intracellular O₂, the analysis shows that at the onset of muscle contraction, O₂ declines immediately and reaches new steady states as contraction intensity rises. Moreover, lactate formation increases even under quite aerobic condition.

Sex differences in the oxygen delivery, extraction, and uptake during moderate-walking exercise transition

Previous studies in children and older adults demonstrated faster oxygen uptake (V̇O2) kinetics in males compared with females, but young healthy adults have not been studied. We hypothesized that young men would have faster aerobic system dynamics in response to the onset of exercise than women. Interactions between oxygen supply and utilization were characterized by the dynamics of V̇O2, deoxyhemoglobin (HHb), tissue saturation index (TSI), cardiac output (Q̇), and calculated arteriovenous O2 difference (a–vO2diff) in women and men. Eighteen healthy active young women and men (9 of each sex) with similar aerobic fitness levels volunteered for this study. Participants performed an incremental cardiopulmonary treadmill exercise test and 3 moderate-intensity treadmill exercise tests (at 80% V̇O2 of gas exchange threshold). Data related to the moderate exercise were submitted to exponential data modelling to obtain parameters related to the aerobic system dynamics. The time constants of V̇O2, a–vO2diff, HHb, and TSI (30 ± 6, 29 ± 1, 16 ± 1, and 15 ± 2 s, respectively) in women were statistically (p < 0.05) faster than the time constants in men (42 ± 10, 49 ± 21, 19 ± 3, and 20 ± 4 s, respectively). Although Q̇ dynamics were not statistically different (p = 0.06) between groups, there was a trend to slower Q̇ dynamics in men corresponding with the slower V̇O2 kinetics. These results indicated that the peripheral and pulmonary oxygen extraction dynamics were remarkably faster in women. Thus, contrary to the hypothesis, V̇O2 dynamics measured at the mouth at the onset of submaximal treadmill walking were faster in women compared with men.

AN EFFECTIVE TECHNOLOGY TO EVALUATE VIBRATION COMFORTABILITY OF HUMAN BODY BASED ON NEAR-INFRARED SPECTROSCOPY

In the biomedical field, Near-Infrared Spectroscopy (NIRS) is often used to determine the physiological information by the noninvasive detection of the regional tissue oxygen saturation (rSO2). Because the fatigue degree of body could be obviously demonstrated by the oxygen saturation under different vibration conditions, an effective technology to evaluate the vibration comfortability by rSO2 is innovatively proposed in this paper. Without losing generality, the vibration comfortability is analyzed by taking the driving position for example. Different from much more factors in previous approaches, only four main body factors, i.e., brain, musculus biceps brachii, erector spinae and biceps femoris, and three main influence factors on vibration comfortability, i.e., acceleration, frequency, and exposure time, are taken into account in our technology. Under different conditions of the three vibration factors, the rSO2 for the four body factors is detected one by one. Then the relationship among the rSO2, subjective feeling, and the vibration parameters can be obtained by the least square method, and the quantitative evaluation model on vibration comfortability is established. It is found experimentally that the rSO2 trends of musculus biceps brachii, erector spinae and biceps femoris are all greatly increased with the acceleration and frequency, but brain is decreasing obviously. Through our experiment it is verified that this technology can be used in objectively and effectively evaluating under different vibration conditions. This novel technology could provide theoretical support for vibration comfortability assessment and have potential applications in other relative fields.

Evaluation of muscle oxygenation by near infrared spectroscopy in patients with facioscapulohumeral muscular dystrophy

The purpose of the study was to determine muscle metabolism adaptation to exercise in facioscapulohumeral muscular dystrophy patients (FSHD) and to study the correlation with clinical functional status (6-min walk test). 8 FSHD patients and 15 age-matched healthy controls (Controls) performed two isokinetic constant-load knee extension exercises: (1) at 20% of their maximal extensors' peak torque (i.e., the same relative workload) and (2) at (20N⋅m) (the same absolute workload) for up to 4 min. All exercises consisted of rhythmic, voluntary, isokinetic, concentric contractions of the quadriceps femoris at 90°/s, whereas the flexion was performed passively at the same speed. Muscle oxygenation in the vastus lateralis was evaluated using near-infrared spectroscopy (NIRS). The FSHD patients displayed a lower maximal peak torque than controls (-41%, p < 0.05). During the two-exercise modalities, deoxygenated haemoglobin (HHb) and total haemoglobin volume (tHb) were lower in the FSHD patients (p < 0.05). The initial muscle deoxygenation time delay was shorter in the control group (FSHD: 15.1 ± 4.1 s vs.

CONTROLS

10.4 ± 2.1 s, p < 0.05). Mean response time and maximal peak torque were both correlated with functional impairment (walking endurance). The results suggest that FSHD patients present an impairment in their capacity to deliver or to use oxygen.

Evaluation of a textile-based near infrared spectroscopy system in calf muscle oxygenation measurements

We recently introduced a novel textile-based NIRS sensor (TexNIRS). Here, we evaluate TexNIRS in ten subjects (16 legs, age 28.5 ± 2.32 years, adipose tissue thickness (ATT) 4.17 ± 1.71 mm). Three venous occlusions at 50 mmHg were performed on their calf muscle. After 3 min of occlusion, oxy/deoxy hemoglobin concentration ([O₂Hb], [HHb]) changes were 3.71 ± 1.89/1.79 ± 1.08 μM; venous oxygen saturation (SvO₂) was 75 ± 9.7 %, oxygen consumption (VO₂) was 0.02 ± 0.01 mL/100 g/min, hemoglobin flow (HF) was 0.93 ± 0.48 μmol/100 mL/min, and blood flow (BF) was 2.01 ± 1.04 mL/100 mL/min. Our results are in good agreement with the literature, but the TexNIRS enables a much higher level of comfort.