Physiological basis of cardiopulmonary rehabilitation in patients with lung or heart disease

Shortness of breath associated with cardiorespiratory abnormalities and peripheral muscle discomfort are the major factors that limit exercise capacity in patients with chronic obstructive pulmonary disease (COPD) and those with congestive heart failure (CHF). Both of these symptoms negatively impact on patients’ daily physical activity levels. In turn, poor daily physical activity is commonly associated with increased rates of morbidity and mortality. Cardiopulmonary rehabilitation programmes partially reverse muscle weakness and dysfunction and increase functional capacity in both COPD and CHF. However, benefits gained from participation in cardiopulmonary rehabilitation programmes are regressing soon after the completion of these programmes. Moreover, several barriers limit access and uptake of cardiopulmonary rehabilitation programmes by eligible patients. A potential solution to the underutilisation of cardiopulmonary rehabilitation is the implementation of tele-rehabilitation interventions at home using information and communications technologies. Thus, tele-rehabilitation may be useful to encourage and educate patients with COPD or CHF on how best to maintain and/or further enhance daily physical activity levels

Contrasting the physiological effects of heliox and oxygen during exercise in a patient with advanced COPD

In COPD patients the ergogenic effect of heliox or oxygen breathing might be related both to improvements in ventilatory parameters (that lessen dyspnoea) and to enhanced oxygen delivery to respiratory and locomotor muscles

Contrasting the physiological effects of heliox and oxygen during exercise in a patient with advanced COPD

In COPD patients the ergogenic effect of heliox or oxygen breathing might be related both to improvements in ventilatory parameters (that lessen dyspnoea) and to enhanced oxygen delivery to respiratory and locomotor muscles

Extradiaphragmatic respiratory muscle perfusion during exercise in patients with COPD: impact on dyspnea

Advances in technology, such as the use of nearinfrared spectroscopy to measure local respiratory muscle blood flow,(1) make it possible to investigate whether alterations in respiratory muscle perfusion during exercise contribute to the development of respiratory muscle fatigue and to associated increases in dyspnea perception in patients with COPD

Respiratory and locomotor muscle blood flow during exercise in health and chronic obstructive pulmonary disease

We have developed an indicator‐dilution method to measure muscle blood flow at rest and during exercise using the light absorbing tracer indocyanine green dye (ICG) injected as an intravenous bolus, with surface optodes placed over muscles of interest to record the ICG signal by near‐infrared spectroscopy. Here we review findings for both quadriceps and intercostal muscle blood flow (measured simultaneously) in trained cyclists and in patients with chronic obstructive pulmonary disease (COPD). During resting hyperpnoea in both athletes and patients, intercostal muscle blood flow increased with ventilation, correlating closely and linearly with the work of breathing, with no change in quadriceps flow. During graded exercise in athletes, intercostal flow at first increased, but then began to fall approaching peak effort. Unexpectedly, in COPD, intercostal muscle blood flow during exercise fell progressively from resting values, contrasting sharply with the response to resting hyperpnoea. During exercise at peak intensity, we found no quadriceps blood flow reduction in favour of the respiratory muscles in either athletes or patients. In COPD at peak exercise, when patients breathed 21% oxygen in helium or 100% oxygen, there was no redistribution of blood flow observed between legs and respiratory muscles in either direction. Evidence of decrease in leg blood flow and increase in respiratory muscle flow was found only when imposing expiratory flow limitation (EFL) during exercise in healthy individuals. However, because EFL caused substantial physiological derangement, lowering arterial oxygen saturation and raising end‐tidal urn:x-wiley:09580670:media:eph12704:eph12704-math-0001 and heart rate, these results cannot be projected onto normal exercise

Heterogeneity of blood flow and metabolism during exercise in patients with chronic obstructive pulmonary disease.

The study investigated whether the capacity to regulate muscle blood flow (Q) relative to metabolic demand (VO2) is impaired in COPD. Using six NIRS optodes over the upper, middle and lower vastus lateralis in 6 patients, (FEV1:46 ± 12%predicted) we recorded from each: a) Q by indocyanine green dye injection, b) VO2/Q ratios based on fractional tissue O2 saturation and c) VO2 as their product, during constant-load exercise (at 20%, 50% and 80% of peak capacity) in normoxia and hyperoxia (FIO2:1.0). At 50 and 80%, relative dispersion (RD) for Q, but not for VO2, was greater in normoxia (0.67 ± 0.07 and 0.79 ± 0.08, respectively) compared to hyperoxia (0.57 ± 0.12 and 0.72 ± 0.07, respectively). In both conditions, RD for VO2 and Q significantly increased throughout exercise; however, RD of VO2/Q ratio was minimal (normoxia: 0.12–0.08 vs hyperoxia: 0.13–0.09). Muscle Q and VO2 appear closely matched in COPD patients, indicating a minimal impact of heterogeneity on muscle oxygen availability at submaximal levels of exercise

Near-infrared spectroscopy using indocyanine green dye for minimally invasive measurement of respiratory and leg muscle blood flow in patients with COPD

Reliability of Near-infrared spectroscopy (NIRS), measuring indocyanine green (ICG) for minimally invasive assessment of relative muscle blood flow during exercise has been examined in fit young individuals, but not in COPD. Here we ask whether it could be used to evaluate respiratory and locomotor muscle perfusion in COPD patients. Vastus lateralis muscle blood flow (MBF, the reference method calculated from arterial and muscle ICG concentration curves) and a blood flow index (BFI, calculated using only the (same) muscle ICG concentration curves) were compared in 10 patients (FEV1:51{plus minus}6%predicted) at rest and during cycling at 25%, 50%, 75% and 100% of WRpeak. Intercostal muscle MBF and BFI were also compared during isocapnic hyperpnea at rest, reproducing ventilation levels up to those at WRpeak. Intercostal and vastus lateralis BFI increased with increasing ventilation during hyperpnea (from 2.5{plus minus}0.3 to 4.5{plus minus}0.7nM/s) and cycling load (from 1.0{plus minus}0.2 to 12.8{plus minus}1.9nM/s), respectively. There were strong correlations between BFI and MBF for both intercostal (r=0.993 group mean data, r=0.872 individual data) and vastus lateralis (r=0.994 group mean data, r=0.895 individual data). Fold changes from rest in BFI and MBF did not differ for either the intercostal muscles or the vastus lateralis. Group mean BFI data showed strong interrelationships with respiratory and cycling workload, and whole body metabolic demand (r ranged from 0.913 to 0.989) simultaneously recorded during exercise. We conclude that BFI is a reliable and minimally invasive tool for evaluating relative changes in respiratory and locomotor muscle perfusion from rest to peak exercise in COPD patient groups

A study of clinical and physiological relations of daily physical activity in precapillary pulmonary hypertension.

Daily physical activity is reduced in precapillary pulmonary hypertension (PH) but the underlying mechanisms are inadequately explored. We sought to investigate clinical and physiological relations of daily physical activity and profile differences between less and more active patients with precapillary PH. A prospective, cross-sectional study of 20 patients with precapillary PH who undertook a) a comprehensive clinical assessment, b) a preliminary treadmill test, c) 7-day monitoring of daily walking intensity with triaxial accelerometry and d) a personalized treadmill test corresponding to the individual patient mean daily walking intensity with real-time physiological measurements. Significant clinical correlations with individual patient mean walking intensity (1.71±0.27 m/s2) were observed for log N-terminal pro-brain natriuretic peptide (log-NTproBNP: r=-.75, p=<.001), age (r=-.70, p=.001), transfer factor for carbon monoxide %predicted (r=.51, p=0.022) and 6-minute walk distance (r=.50, p=.026). Significant physiological correlations were obtained for heart rate reserve (r=.68, p=.001), quadriceps tissue oxygenation index (Q-StO2: r=.58, p=.008), change in Q-StO2 from rest (r=.60, p=.006) and ventilatory equivalent for oxygen uptake (r=-.56, p=.013). Stepwise multiple regression analyses retained log-NTproBNP (R2=0.55), heart rate reserve (R2=0.44) and Q-StO (R2=0.13) accounting for a significant variance in individual walking intensity. Less active patients had greater physical activity-induced cardiopulmonary impairment, worse quadriceps oxygenation profile and compromised health-related quality of life compared to more active patients. These preliminary findings suggest a significant relation between right ventricular and peripheral muscle oxygenation status and reduced daily physical activity in precapillary PH. Further research is warranted to unravel the physiological determinants, establish clinical predictors, and identify beneficial interventions

Interval training induces clinically meaningful effects in daily activity levels in COPD

Mounting evidence suggests that daily activity levels (DAL) in patients with chronic obstructive pulmonary disease (COPD) are markedly low compared with healthy age-matched individuals and are associated with poorer health status and prognosis [1]. COPD severity negatively impacts on DAL since patients with low DAL experience greater ventilatory, central haemodynamic and peripheral muscle oxygenation constraints during activities of daily living when compared with more physically active counterparts [2, 3]. Although exercise training as part of pulmonary rehabilitation has shown to mitigate the aforementioned physiological constraints [4], there is no evidence of clinically meaningful improvements in DAL following pulmonary rehabilitation [5] as manifested by a mean increase of at least 1000 steps·day−1 [6]. This has been attributed to methodological shortfalls, such as lack of adequately controlled studies, small sample size, short duration of pulmonary rehabilitation programmes, application of activity monitors non-validated for COPD patients [5] and insufficient exercise intensities to induce true physiological training effects. Interval exercise training has been shown to allow application of intense loads to peripheral muscles that induce substantial physiological effects manifested by mitigation of respiratory and central haemodynamic limitations and partial restoration of peripheral muscle dysfunction in patients with diverse COPD severity [7, 8]. In this context, it is reasoned that application of this training modality would allow transfer of the aforementioned physiological benefits into clinically meaningful improvements in DAL [2, 3]. Accordingly, the purpose of this randomised controlled study was to investigate the effect of a 12-week high-intensity interval exercise training programme in DAL in addition to usual care in patients with COPD

Limitation in tidal volume expansion partially determines the intensity of physical activity in COPD

open8In patients with Chronic Obstructive Pulmonary Disease (COPD) reduced levels of daily physical activity are associated with the degree of impairment in lung, peripheral muscle and central hemodynamic function. There is however, limited evidence as to whether limitations in tidal volume expansion also, importantly determine daily physical activity levels in COPD. Eighteen consecutive COPD patients [9 active (FEV1:1.59±0.64 liters) with an average daily movement intensity >1.88 m/sec(2) and 9 less active patients (FEV1:1.16±0.41 liters) with an average intensity <1.88 m/sec(2)] underwent a 4-min treadmill test at a constant speed corresponding to each individual patient's average movement intensity, captured by a triaxial accelerometer during a preceding 7-day period. When chest wall volumes, captured by Optoelectronic Plethysmography, were expressed relative to comparable levels of minute ventilation (ranging between 14.5±4.3 to 33.5±4.4 liters/min), active patients differed from the less active ones in terms of the lower increase in end-expiratory chest wall volume (by 0.15±0.17 versus 0.45±0.21 liters), the greater expansion in tidal volume (by 1.76±0.58 versus 1.36±0.24 liters) and the larger inspiratory reserve chest wall volume (IRVcw: by 0.81±0.25 versus 0.39±0.27 liters). IRVcw (r(2)=0.420), expiratory flow (r(2) change=0.174) and Borg dyspnoea score (r(2) change=0.123) emerged as the best contributors accounting for 71.7\% of the explained variance in daily movement intensity. COPD patients exhibiting greater ability to expand tidal volume and to maintain adequate inspiratory reserve volume tend to be more physically active. Thus, interventions aiming at mitigating restrictions on operational chest wall volumes are expected to enhance daily physical activity levels in COPD.openE. A. Kortianou;A. Aliverti;Z. Louvaris;M. Vasilopoulou;I. Nasis;A. Asimakos;S. G. Zakynthinos;I. VogiatzisE. A., Kortianou; Aliverti, Andrea; Z., Louvaris; M., Vasilopoulou; I., Nasis; A., Asimakos; S. G., Zakynthinos; I., Vogiatzi