A practical approach to assess leg muscle oxygenation during ramp-incremental cycle ergometry in heart failure

Age, sex, endurance capacity, and chronic heart failure affect central and peripheral factors of oxygen uptake measured by non-invasive and continuous technologies: support of pioneer work using invasive or non-continuous measures

Introduction

It is known that maximum oxygen uptake depends on age, sex, endurance capacity, and chronic heart failure. However, due to the required invasive or often applied non-continuous approaches, less is known on underlying central and peripheral factors. Thus, this study aimed to investigate the effects of age, sex, endurance capacity, and chronic heart failure on non-invasively and continuously measured central and peripheral factors of oxygen uptake.

Methods

15 male children (11 ± 1 years), 15 male (24 ± 3 years) and 14 female recreationally active adults (23 ± 2 years), 12 male highly trained endurance athletes (24 ± 3 years), and 10 male elders (59 ± 6 years) and 10 chronic heart failure patients (62 ± 7 years) were tested during a cardiopulmonary exercise test on a cycling ergometer until exhaustion for: blood pressure, heart rate, stroke volume, cardiac output, cardiac power output, vastus lateralis muscle oxygen saturation, and (calculated) arterio-venous oxygen difference. For the non-invasive and continuous measurement of stroke volume and muscle oxygen saturation, bioreactance analysis and near-infrared spectroscopy were used, respectively. A two-factor repeated measure ANOVA and partial eta-squared effect sizes (η p 2 ) were applied for statistical analyses at rest, 80, and 100% of oxygen uptake.

Results

For the age effect, there were statistically significant group differences for all factors (p ≤ .033; η p 2 ≥ .169 ). Concerning sex, there were group differences for all factors (p ≤ .010; η p 2 ≥ .223 ), except diastolic blood pressure and heart rate (p ≥ .698; η p 2 ≤ .006 ). For the effect of endurance capacity, there were no group differences for any of the factors (p ≥ .065; η p 2 ≤ .129 ). Regarding chronic heart failure, there were group differences for the heart rate and arterio-venous oxygen difference (p ≤ .037; η p 2 ≥ .220 ).

Discussion

Age, sex, endurance capacity, and chronic heart failure affect central and peripheral factors of oxygen uptake measured by non-invasive and continuous technologies. Since most of our findings support pioneer work using invasive or non-continuous measures, the validity of our applied technologies is indirectly confirmed. Our outcomes allow direct comparison between different groups serving as reference data and framework for subsequent studies in sport science and medicine aiming to optimise diagnostics and interventions in athletes and patients.

The Effect of Adding Noninvasive Ventilation to High-Intensity Exercise on Peripheral and Respiratory Muscle Oxygenation

BACKGROUND

We sought to assess whether noninvasive ventilation (NIV) as an adjunct with high-intensity exercise (HIEx) is more effective than exercise alone or exercise + sham on respiratory and peripheral oxygenation and vascular function in subjects with coexisting COPD and heart failure (HF).

METHODS

On separate days, subjects performed incremental cardiopulmonary exercise testing and 3 constant load tests: HIEx, HIEx+NIV, and HIEx+sham (bi-level mode, Astral 150). Subjects were randomized with a 1:1 block allocation for the HIEx+NIV group and HIEx+sham group until the limit of tolerance (Tlim). Peripheral and respiratory oxygenation were assessed by oxyhemoglobin (O2Hb) and deoxyhemoglobin (Hb) using near-infrared spectroscopy in the respiratory and peripheral musculature. Vascular function was assessed by endothelial function using the flow-mediated vasodilation (FMD) method.

RESULTS

There was a significant increase in FMD (mm), FMD (%), and shear stress in the HIEx+NIV group when compared to HIEx or HIEx+sham (P < .05). Less extraction of O2 (Hb) in the peripheral and respiratory muscles was observed in the HIEx+NIV group (P < .05). We also found correlations between peripheral muscle oxygenation (O2Hb) at the moment 80% of Tlim (r = 0.71, P = .009) and peak of Tlim (100%) (r = 0.76, P = .004) with absolute FMD (mm) immediately after HIEx+NIV.

CONCLUSIONS

NIV as an adjunct to HIEx can acutely unload the respiratory musculature with better redistribution of available blood flow and beneficially modulate endothelial function. These results may influence the approach to cardiopulmonary rehabilitation in patients with coexisting COPD-HF.

Quantifying leg muscle deoxygenation during incremental cycling in hypoxemic patients with fibrotic interstitial lung disease

BACKGROUND

Hypoxaemia and cardiocirculatory abnormalities may impair muscle oxygen (O₂ ) delivery relative to O₂ requirements thereby increasing the rate of O₂ extraction during incremental exercise in fibrotic interstitial lung disease (f-ILD). Using changes in deoxyhaemoglobin concentration ([HHb]) by near-infrared spectroscopy (NIRS) as a proxy of O₂ extraction, we investigated whether a simplified (double-linear) approach, previously tested in heart failure, would provide useful estimates of muscle deoxygenation in f-ILD.

METHODS

A total of 25 patients (23 men, 72 ± 8 years; 20 with idiopathic pulmonary fibrosis, lung diffusing capacity for carbon monoxide = 44 ± 11% predicted) and 12 age- and sex-matched healthy controls performed incremental cycling to symptom limitation. Changes in vastus lateralis [HHb] assessed by NIRS were analysed in relation to work rate (WR) and O₂ uptake throughout the exercise.

RESULTS

Patients showed lower exercise capacity than controls (e.g., peak WR = 67 ± 18% vs. 105 ± 20% predicted, respectively; p < 0.001). The [HHb] response profile was typically S-shaped, presenting three distinct phases. Exacerbated muscle deoxygenation in patients versus controls was evidenced by: (i) a steeper mid-exercise [HHb]-WR slope (0.30 ± 0.22 vs. 0.11 ± 0.08 μmol/W; p = 0.008) (Phase 2), and (ii) a larger late-exercise increase in [HHb] (p = 0.002) (Phase 3). Steeper [HHb]-WR slope was associated with lower peak WR (r = -0.70) and greater leg discomfort (r = 0.77; p < 0.001) in f-ILD.

CONCLUSION

This practical approach to interpreting [HHb] during incremental exercise might prove useful to determine the severity of muscle deoxygenation and the potential effects of interventions thereof in hypoxemic patients with f-ILD.

High-Intensity Inspiratory Muscle Training Improves Scalene and Sternocleidomastoid Muscle Oxygenation Parameters in Patients With Weaning Difficulties: A Randomized Controlled Trial

Background

Critically ill patients who have difficulties weaning from the mechanical ventilator are prone to develop respiratory muscle weakness. Inspiratory muscle training (IMT) can improve respiratory muscle strength. Whether IMT can improve scalene and sternocleidomastoid muscle oxygenation parameters is unknown.

Aim

To compare changes in muscle oxygenation parameters of scalene and sternocleidomastoid inspiratory muscles during a standardized task between patients with weaning difficulties who received either high-intensity IMT (intervention) or sham low-intensity IMT (control).

Method

Forty-one patients performed daily IMT sessions (4 sets, 6–10 breaths) until weaning success or for 28 consecutive days. The training load was progressively adjusted in the intervention group (n = 22) to the highest tolerable load, whilst the control group (n = 19) kept training at 10% of their baseline maximal inspiratory pressure (PImax). Breathing characteristics (i.e., work and power of breathing, PoB), respiratory muscle function [i.e., PImax and forced vital capacity (FVC)] were measured during a standardized loaded breathing task against a load of 30% of baseline PImax before and after the IMT period. In addition, during the same loaded breathing task, absolute mean and nadir changes from baseline in local scalene and sternocleidomastoid muscle oxygen saturation index (Δ%StiO2) (an index of oxygen extraction) and nadir Δ%StiO2 normalized for the PoB were measured by near-infrared spectroscopy.

Results

At post measures, only the intervention group improved mean PoB compared to pre measures (Pre: 0.42 ± 0.33 watts, Post: 0.63 ± 0.51watts, p-value &lt; 0.01). At post measures, both groups significantly improved nadir scalene muscles StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) compared to pre measurements and the improvement was not significant different between groups (p-value = 0.40). However, at post measures, nadir sternocleidomastoid muscle StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) was significantly greater improved in the intervention group (mean difference: +18.4, 95%CI: −1.4; 38.1) compared to the control group (mean difference: +3.7, 95%CI: −18.7; 26.0, between group p-value &lt; 0.01). Both groups significantly improved PImax (Intervention: +15 ± 13 cmH2O p-value &lt; 0.01, Control: +13 ± 15 cmH2O p-value &lt; 0.01). FVC only significantly improved in the intervention group (+0.33 ± 0.31 L p &lt; 0.01) report also change in control group.

Conclusion

This exploratory study suggests that high-intensity IMT induces greater improvements in scalene and sternocleidomastoid muscle oxygenation parameters attributed for oxygen delivery, utilization and oxygen saturation index compared to low-intensity IMT in patients with weaning difficulties.

Can Non-invasive Ventilation Modulate Cerebral, Respiratory, and Peripheral Muscle Oxygenation During High-Intensity Exercise in Patients With COPD-HF?

Aim

To evaluate the effect of non-invasive positive pressure ventilation (NIPPV) on (1) metabolic, ventilatory, and hemodynamic responses; and (2) cerebral (Cox), respiratory, and peripheral oxygenation when compared with SHAM ventilation during the high-intensity exercise in patients with coexisting chronic obstructive pulmonary disease (COPD) and heart failure (HF).

Methods and Results

On separate days, patients performed incremental cardiopulmonary exercise testing and two constant-work rate tests receiving NIPPV or controlled ventilation (SHAM) (the bilevel mode—Astral 150) in random order until the limit of tolerance (Tlim). During exercise, oxyhemoglobin (OxyHb+Mb) and deoxyhemoglobin (DeoxyHb+Mb) were assessed using near-infrared spectroscopy (Oxymon, Artinis Medical Systems, Einsteinweg, The Netherlands). NIPPV associated with high-intensity exercise caused a significant increase in exercise tolerance, peak oxygen consumption (V·O2 in mlO₂·kg⁻¹·min⁻¹), minute ventilation peak (V·E in ml/min), peak peripheral oxygen saturation (SpO₂, %), and lactate/tlim (mmol/s) when compared with SHAM ventilation. In cerebral, respiratory, and peripheral muscles, NIPPV resulted in a lower drop in OxyHb+Mb (p < 0.05) and an improved deoxygenation response DeoxyHb+Mb (p < 0.05) from the half of the test (60% of Tlim) when compared with SHAM ventilation.

Conclusion

Non-invasive positive pressure ventilation during constant work-rate exercise led to providing the respiratory muscle unloading with greater oxygen supply to the peripheral muscles, reducing muscle fatigue, and sustaining longer exercise time in patients with COPD-HF.

Relationship Between the Borg Scale Rating of Perceived Exertion and Leg-Muscle Deoxygenation During Incremental Exercise in Healthy Adults

INTRODUCTION

The Borg scale rating of perceived exertion is a reliable indicator and widely used to monitor and guide exercise intensity. We aimed to evaluate the relationships between the Borg scale score and oxygenated hemoglobin (O2Hb) and deoxygenated hemoglobin (HHb) concentrations in the leg muscle as measured by near-infrared spectroscopy (NIRS) during cardiopulmonary exercise testing (CPET) in healthy adult men. We also investigated the relationships between the Borg scale score and the work rate (WR), heart rate (HR), oxygen uptake (VO₂), and minute ventilation (VE).

METHODS

Participants comprised 12 healthy men. Cardiopulmonary and NIRS parameters were assessed during each minute of CPET and at the end of the test.

RESULTS

The Borg scale score was significantly correlated with cardiopulmonary parameters including WR, HR, VO₂, and VE during CPET (Rs = 0.87-0.95; p < 0.05). Furthermore, the Borg scale score was significantly correlated with NIRS parameters including O2Hb and HHb levels during CPET (Rs = -0.48 and 0.45, respectively; p < 0.05).

DISCUSSION

The Borg scale score is significantly correlated with cardiopulmonary parameters (WR, HR, VO₂, and VE), as well as with leg-muscle oxygenation parameters as assessed by NIRS, during CPET in healthy adults. The correlation coefficients obtained from NIRS parameters were lower than those of cardiopulmonary parameters.

CONCLUSIONS

The Borg scale score might better reflect cardiopulmonary responses than muscle deoxygenation during exercise. These results can aid in the planning of rehabilitation programs for healthy adults.

Non-invasively measured central and peripheral factors of oxygen uptake differ between patients with chronic heart failure and healthy controls

Background

Maximum oxygen uptake is an established measurement of diagnosing chronic heart failure and underlies various central and peripheral factors. However, central and peripheral factors are little investigated, because they are usually measured invasively. The aim of this study was to compare non-invasively measured central and peripheral factors of oxygen uptake between patients with chronic heart failure and healthy controls.

Methods

Ten male patients with heart failure with reduced ejection fraction (62 ± 4 years; body mass index: 27.7 ± 1.8 kg/m²; ejection fraction: 30 ± 4%) and ten male healthy controls (59 ± 3 years; body mass index: 27.7 ± 1.3 kg/m²) were tested for blood pressure, heart rate, stroke volume, cardiac output, and cardiac power output (central factors) as well as muscle oxygen saturation of the vastus lateralis and biceps brachii muscle (peripheral factors) during an incremental cycling test. Stroke volume and muscle oxygen saturation were non-invasively measured by a bioreactance analysis and near-infrared spectroscopy, respectively. Additionally, a maximum isometric strength test of the knee extensors was conducted. Magnitude-based inferences were computed for statistical analyses.

Results

Patients had a likely to most likely lower oxygen uptake, mean arterial pressure, and heart rate at maximum load as well as very likely lower isometric peak torque. Contrary, patients had a possibly to likely higher stroke volume and muscle oxygen saturation of the vastus lateralis muscle at maximum load. Differences in cardiac output, cardiac power output, and muscle oxygen saturation of the biceps brachii muscle at maximum load were unclear.

Conclusions

Non-invasively measured central and peripheral factors of oxygen uptake differ between patients with chronic heart failure and healthy controls. Therefore, it is promising to measure both types of factors in patients with chronic heart failure to optimize the diagnosis and therapy.

Effect of high-intensity exercise on cerebral, respiratory and peripheral muscle oxygenation of HF and COPD-HF patients

OBJECTIVE

To investigate cerebral oxygenation (Cox) responses as well as respiratory (Res) and active peripheral muscle (Pm) O₂ delivery during high-intensity cycling exercise and contrast responses between patients with coexistent chronic obstructive pulmonary disease (COPD)-heart failure (HF) and HF alone.

METHODS

Cross-sectional study involving 11 COPD-HF and 11 HF patients. On two different days, patients performed maximal incremental cardiopulmonary exercise testing (CPET) and constant load exercise on a cycle ergometer until the limit of tolerance (Tlim). The high-intensity exercise session was 80% of the peak CPET work rate. Relative blood concentrations of oxyhemoglobin ([O₂Hb]), deoxyhemoglobin ([HHb]) of Res, Pm (right vastus lateralis) and Cox (pre-frontal) were measured using near infrared spectroscopy.

RESULTS

We observed a greater decrease in [O₂Hb] at a lower Tlim in COPD-HF when compared to HF (P < 0.05). [HHb] of Res was higher (P < 0.05) and Tlim was lower in COPD-HF vs. HF. Pm and Cox were lower and Tlim was higher in (P < 0.05) HF vs. COPD-HF. In HF, there was a lower ∆[O₂Hb] and higher ∆ [HHb] of Pm when contrasted to Cox observed during exercise, as well as a lower ∆ [O₂Hb] and higher ∆ [HHb] of Res when contrasted with Cox (P < 0.05). However, COPD-HF patients presented with a higher ∆ [HHb] of Res and Pm when contrasted with Cox (P < 0.05).

CONCLUSION

The coexistence of COPD in patients with HF produces negative effects on Cox, greater deoxygenation of the respiratory and peripheral muscles and higher exertional dyspnea, which may help to explain an even lower exercise tolerance in this multimorbidity phenotype.