Influence of respiratory pressure support on hemodynamics and exercise tolerance in patients with COPD

Wearable positive end-expiratory pressure valve improves exercise performance

We tested a PEEP (4.2 cmH₂O) mouthpiece (PMP) on maximal cycling performance in healthy adults. Experiment-1, PMP vs. non-PMP mouthpiece (CON) [n = 9 (5♂), Age = 30 ± 2 yr]; Experiment-2, PMP vs. no mouthpiece (NMP) [n = 10 (7♂), Age = 27 ± 1 yr]. At timepoint 1 in both experiments (mouthpiece condition randomized) subjects performed graded cycling testing (GXT) (Corival® cycle ergometer) to determine V˙O_{2peak (ml∗kg∗min}⁻¹), O₂pulse _(mlO2∗bt⁻¹), GXT endurance time (GXT-T_(s)), and V˙O_{2(ml∗kg∗min}⁻¹)-at-ventilatory-threshold (V˙O₂ @VT). At timepoint 2 72 h later, subjects completed a ventilatory-threshold-endurance-ride [VTER_(s)] timed to exhaustion at V˙O₂ @VT power _(W). One week later at timepoints 3 and 4 (time-of-day controlled), subjects repeated testing protocols under the alternate mouthpiece condition. Selected results (paired T-test, p<0.05): Experiment 1 PMP vs. CON, respectively: V˙O_2peak ​= ​45.2 ​± ​2.4 vs. 42.4 ​± ​2.3 p<0.05; V˙O₂@VT ​= ​33.7 ​± ​2.0 vs. 32.3 ​± ​1.6; GXT-TTE ​= ​521.7 ​± ​73.4 vs. 495.3 ​± ​72.8 (p<0.05); VTER ​= ​846.2 ​± ​166.0 vs. 743.1 ​± ​124.7; O2pulse ​= ​24.5 ​± ​1.4 vs. 23.1 ​± ​1.3 (p<0.05). Experiment 2 PMP vs. NMP, respectively: V˙O_2peak ​= ​43.3 ​± ​1.6 vs. 41.7 ​± ​1.6 (p<0.05); V˙O₂@VT ​= ​31.1 ​± ​1.2 vs. 29.1 ​± ​1.3 (p<0.05); GXT-TTE ​= ​511.7 ​± ​49.6 vs. 486.4 ​± ​49.6 (p<0.05); VTER 872.4 ​± ​134.0 vs. 792.9 ​± ​122.4; O₂pulse ​= ​24.1 ​± ​0.9 vs. 23.4 ​± ​0.9 (p<0.05). Results demonstrate that the PMP conferred a significant performance benefit to cyclists completing high intensity cycling exercise.

NIV Is not Adequate for High Intensity Endurance Exercise in COPD

Noninvasive ventilation (NIV) during exercise has been suggested to sustain higher training intensity but the type of NIV interface, patient-ventilator asynchronies (PVA) or technological limitation of the ventilator may interfere with exercise. We assessed whether these parameters affect endurance exercise capacity in severe COPD patients. In total, 21 patients with severe COPD not eligible to home NIV performed three constant workload tests. The first test was carried out on spontaneous breathing (SB) and the following ones with NIV and a nasal or oronasal mask in a randomized order. PVA and indicators of ventilator performance were assessed through a comprehensive analysis of the flow pressure tracing raw data from the ventilator. The time limit was significantly reduced with both masks (406 s (197–666), 240 s (131–385) and 189 s (115–545), p < 0.01 for tests in SB, with oronasal and nasal mask, respectively). There were few PVA with an oronasal mask (median: 3.4% (1.7–5.2)) but the ventilator reached its maximal generating capacity (median flowmax: 208.0 L/s (189.5–224.8) while inspiratory pressure dropped throughout exercise (from 10.1 (9.4–11.4) to 8.8 cmH2O (8.6–10.8), p < 0.01). PVA were more frequent with nasal mask (median: 12.8% (3.2–31.6), p < 0.01). Particularly, the proportion of patients with ineffective efforts > 10% was significantly higher with nasal interface (0% versus 33.3%, p < 0.01). NIV did not effectively improve endurance capacity in COPD patients not acclimated to home NIV. This was due to a technological limitation of the ventilator for the oronasal mask and the consequence either of an insufficient pressure support or a technological limitation for the nasal mask.

The effect of carotid chemoreceptor inhibition on exercise tolerance in chronic obstructive pulmonary disease: A randomized-controlled crossover trial

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) have an exaggerated ventilatory response to exercise, contributing to exertional dyspnea and exercise intolerance. We recently demonstrated enhanced activity and sensitivity of the carotid chemoreceptor (CC) in COPD which may alter ventilatory and cardiovascular regulation and negatively affect exercise tolerance. We sought to determine whether CC inhibition improves ventilatory and cardiovascular regulation, dyspnea and exercise tolerance in COPD.

METHODS

Twelve mild-moderate COPD patients (FEV₁ 83 ± 15 %predicted) and twelve age- and sex-matched healthy controls completed two time-to-symptom limitation (T_LIM) constant load exercise tests at 75% peak power output with either intravenous saline or low-dose dopamine (2 μg·kg^-1·min^-1, order randomized) to inhibit the CC. Ventilatory responses were evaluated using expired gas data and dyspnea was evaluated using a modified Borg scale. Inspiratory capacity maneuvers were performed to determine operating lung volumes. Cardiac output was estimated using impedance cardiography and vascular conductance was calculated as cardiac output/mean arterial pressure (MAP).

RESULTS

At a standardized exercise time of 4-min and at T_LIM; ventilation, operating volumes and dyspnea were unaffected by dopamine in COPD patients and controls. In COPD, dopamine decreased MAP and increased vascular conductance at all time points. In controls, dopamine increased vascular conductance at T_LIM, while MAP was unaffected.

CONCLUSION

There was no change in time to exhaustion in either group with dopamine. These data suggest that the CC plays a role in cardiovascular regulation during exercise in COPD; however, ventilation, dyspnea and exercise tolerance were unaffected by CC inhibition in COPD patients.

Quadriceps Endurance Increases Following Cycling Exercise With Non-Invasive Ventilation In Moderate-To-Severe COPD Patients. A Non-Randomized Controlled Study

Purpose

Application of non-invasive ventilation (NIV) during exercise improves exercise tolerance in severe COPD patients; however, the underlying mechanism is only partially unraveled. As part of its known effect to unload the respiratory muscles, we looked for the influence of NIV on post-exercise quadriceps muscle endurance.

Patients and methods

We included 25 severe COPD patients entering an outpatient pulmonary rehabilitation program. They performed, on successive days, three quadriceps endurance tests at 70% of the maximal strength (1RM) to task failure (TlimQ); 1) control condition; 2) following constant load cycling exercise to exhaustion without Inspiratory Pressure Support (TlimQ IPS-); 3) following the same cycling exercise with IPS (TlmQ IPS+).

Results

Dyspnea Borg score was significantly reduced at the end of the constant load cycling exercise with IPS+ compared to IPS- (3.5±2.6 to 4.3±2.3, p<0.05). Compared to controlled condition, TlimQ was reduced from 78.9±22.7 s to 64.7±22.1 s (p<0.01) with IPS+ and to 48.9±13.7 s (p<0.001) with IPS-. Sensitive analysis revealed a positive effect of NIV on TlimQ in only 15 of the 25 included patients (60%) and was unpredictable from exercise tolerance or maximal quadriceps strength.

Conclusion

Using a simple muscle endurance test, we showed the protective effect of NIV on the exercise-induced quadriceps dysfunction. This beneficial effect is inconstant in our small series of patients and could not be predicted by exercise capacity or endurance to exercise. However, measuring quadriceps muscle endurance following a session of exercise could determine in which patient NIV would improve the benefit of pulmonary rehabilitation.

Non-Invasive Ventilation as an Adjunct to Exercise Training in Chronic Ventilatory Failure: A Narrative Review

BACKGROUND

Chronic ventilatory failure (CVF) may be associated with reduced exercise capacity. Long-term non-invasive ventilation (NIV) may reduce patients' symptoms, improve health-related quality of life and reduce mortality and hospitalisations. There is an increasing use of NIV during exercise training with the purpose to train patients at intensity levels higher than allowed by their pathophysiological conditions.

OBJECTIVE

This narrative review describes the possibility to train patients with CVF and NIV use as a tool to increase the benefits of exercise training.

METHODS

We searched papers published between 1985 and 2018 in (or with the summary in) English language in PubMed and Scopus databases using the keywords "chronic respiratory failure AND exercise," "non invasive ventilation AND exercise," "pulmonary rehabilitation" and "exercise training."

RESULTS

Exercise training is feasible and effective also in patients with CVF. Assisted ventilation can improve exercise tolerance in different clinical conditions. In patients under long-term home ventilatory support, NIV administered also during walking results in improved oxygenation, decreased dyspnoea and increased walking distance. Continuous positive airway pressure and different modalities of assisted ventilation have been delivered through different interfaces during exercise training programmes. Patients with CVF on long-term NIV may benefit from exercising with the same ventilators, interfaces and settings as used at home.

CONCLUSION

We need more randomised clinical trials to investigate the effects of NIV on exercise training in patients with CVF and define organisation and setting.

Benefits of Whole-Body Vibration, as a Component of the Pulmonary Rehabilitation, in Patients with Chronic Obstructive Pulmonary Disease: A Narrative Review with a Suitable Approach

Background. Appropriate management, including pulmonary rehabilitation, associated with correct diagnosis of chronic obstructive pulmonary disease (COPD) in patients can contribute to improving clinical conditions of these patients. Physical activity is recommended for COPD patients. Whole-body vibration (WBV) is a modality of physical activity. Putting together the biological effects and safe use of WBV, it may be a potentially feasible intervention to add to pulmonary rehabilitation. The purpose of this investigation was to systematically review studies regarding the effects of WBV, as a component of the pulmonary rehabilitation, in patients with COPD. Results. A total of six publications met inclusion for review. There was evidence to support the beneficial use of WBV to improve functional performance of the lower limbs and quality of life. However, the appropriateness of and descriptors of WBV methods were poorly described. Conclusions. The results of this review support the use of WBV as a component of pulmonary rehabilitation to assist management of patients with COPD. However, future research should examine the dose-response curve and optimal dosing regimen of WBV according to standard reporting recommendations for people with COPD. Such an approach will allow comparison among studies and the potential of meta-analysis of randomized controlled trials.

Use of exercise testing in the evaluation of interventional efficacy: an official ERS statement

This document reviews 1) the measurement properties of commonly used exercise tests in patients with chronic respiratory diseases and 2) published studies on their utilty and/or evaluation obtained from MEDLINE and Cochrane Library searches between 1990 and March 2015.

Exercise tests are reliable and consistently responsive to rehabilitative and pharmacological interventions. Thresholds for clinically important changes in performance are available for several tests. In pulmonary arterial hypertension, the 6-min walk test (6MWT), peak oxygen uptake and ventilation/carbon dioxide output indices appear to be the variables most responsive to vasodilators. While bronchodilators do not always show clinically relevant effects in chronic obstructive pulmonary disease, high-intensity constant work-rate (endurance) tests (CWRET) are considerably more responsive than incremental exercise tests and 6MWTs. High-intensity CWRETs need to be standardised to reduce interindividual variability. Additional physiological information and responsiveness can be obtained from isotime measurements, particularly of inspiratory capacity and dyspnoea. Less evidence is available for the endurance shuttle walk test. Although the incremental shuttle walk test and 6MWT are reliable and less expensive than cardiopulmonary exercise testing, two repetitions are needed at baseline. All exercise tests are safe when recommended precautions are followed, with evidence suggesting that no test is safer than others.

Non-invasive ventilation during exercise training for people with chronic obstructive pulmonary disease

BACKGROUND

Exercise training as a component of pulmonary rehabilitation improves health-related quality of life (HRQL) and exercise capacity in people with chronic obstructive pulmonary disease (COPD). However, some individuals may have difficulty performing exercise at an adequate intensity. Non-invasive ventilation (NIV) during exercise improves exercise capacity and dyspnoea during a single exercise session. Consequently, NIV during exercise training may allow individuals to exercise at a higher intensity, which could lead to greater improvement in exercise capacity, HRQL and physical activity.

OBJECTIVES

To determine whether NIV during exercise training (as part of pulmonary rehabilitation) affects exercise capacity, HRQL and physical activity in people with COPD compared with exercise training alone or exercise training with sham NIV.

SEARCH METHODS

We searched the following databases between January 1987 and November 2013 inclusive: The Cochrane Airways Group specialised register of trials, AMED, CENTRAL, CINAHL, EMBASE, LILACS, MEDLINE, PEDro, PsycINFO and PubMed. 

SELECTION CRITERIA

Randomised controlled trials that compared NIV during exercise training versus exercise training alone or exercise training with sham NIV in people with COPD were considered for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion in the review, extracted data and assessed risk of bias. Primary outcomes were exercise capacity, HRQL and physical activity; secondary outcomes were training intensity, physiological changes related to exercise training, dyspnoea, dropouts, adverse events and cost.

MAIN RESULTS

Six studies involving 126 participants who completed the study protocols were included. Most studies recruited participants with severe to very severe COPD (mean forced expiratory volume in one second (FEV1) ranged from 26% to 48% predicted). There was an increase in percentage change peak and endurance exercise capacity with NIV during training (mean difference in peak exercise capacity 17%, 95% confidence interval (CI) 7% to 27%, 60 participants, low-quality evidence; mean difference in endurance exercise capacity 59%, 95% CI 4% to 114%, 48 participants, low-quality evidence). However, there was no clear evidence of a difference between interventions for all other measures of exercise capacity. The results for HRQL assessed using the St George's Respiratory Questionnaire do not rule out an effect of NIV (total score mean 2.5 points, 95% CI -2.3 to 7.2, 48 participants, moderate-quality evidence). Physical activity was not assessed in any study. There was an increase in training intensity with NIV during training of 13% (95% CI 1% to 27%, 67 participants, moderate-quality evidence), and isoload lactate was lower with NIV (mean difference -0.97 mmol/L, 95% CI -1.58mmol/L to -0.36 mmol/L, 37 participants, moderate-quality evidence). The effect of NIV on dyspnoea or the number of dropouts between interventions was uncertain, although again results were imprecise. No adverse events and no information regarding cost were reported. Only one study blinded participants, whereas three studies used blinded assessors. Adequate allocation concealment was reported in four studies.

AUTHORS' CONCLUSIONS

The small number of included studies with small numbers of participants, as well as the high risk of bias within some of the included studies, limited our ability to draw strong evidence-based conclusions. Although NIV during lower limb exercise training may allow people with COPD to exercise at a higher training intensity and to achieve a greater physiological training effect compared with exercise training alone or exercise training with sham NIV, the effect on exercise capacity is unclear. Some evidence suggests that NIV during exercise training improves the percentage change in peak and endurance exercise capacity; however, these findings are not consistent across other measures of exercise capacity. There is no clear evidence that HRQL is better or worse with NIV during training. It is currently unknown whether the demonstrated benefits of NIV during exercise training are clinically worthwhile or cost-effective.

Chronic obstructive pulmonary disease: clinical integrative physiology

Peripheral airway dysfunction, inhomogeneous ventilation distribution, gas trapping, and impaired pulmonary gas exchange are variably present in all stages of chronic obstructive pulmonary disease (COPD). This article provides a cogent physiologic explanation for the relentless progression of activity-related dyspnea and exercise intolerance that all too commonly characterizes COPD. The spectrum of physiologic derangements that exist in smokers with mild airway obstruction and a history compatible with COPD is examined. Also explored are the perceptual and physiologic consequences of progressive erosion of the resting inspiratory capacity. Finally, emerging information on the role of cardiocirculatory impairment in contributing to exercise intolerance in patients with varying degrees of airway obstruction is reviewed.

Whole-body vibration as a mode of dyspnoea free physical activity: a community-based proof-of-concept trial

Background

The potential of whole-body vibration (WBV) as a mode of dyspnoea free physical activity for people with chronic obstructive pulmonary disease (COPD) is unknown among community-based settings. Furthermore, the acute effects of WBV on people with COPD have not been profiled in community-based settings. The aim of this community-based proof-of-concept trial was to describe acute effects of WBV by profiling subjective and objective responses to physical activity.

Findings

Seventeen community-dwelling older adults with COPD were recruited to participate in two sessions; WBV and sham WBV (SWBV). Each session consisted of five one-minute bouts interspersed with five one-minute passive rest periods. The gravitational force was ~2.5 g for WBV and ~0.0 g for SWBV. Reliability of baseline dyspnoea, heart rate, and oxygen saturation was first established and then profiled for both sessions. Acute responses to both WBV and SWBV were compared with repeated measures analysis of variance and repeated contrasts. Small changes in dyspnoea and oxygen saturation lacked subjective and clinical meaningfulness. One session of WBV and SWBV significantly increased heart rate (p ≤ 0.02), although there was no difference among WBV and SWBV (p = 0.67).

Conclusions

This community-based proof-of-concept trial showed that a session of WBV can be completed with the absence of dyspnoea for people with COPD. Furthermore, there were no meaningful differences among WBV and SWBV for heart rate and oxygen saturation. There is scope for long-term community-based intervention research using WBV given the known effects of WBV on peripheral muscle function and functional independence.

Use of positive expiratory pressure during six minute walk test: results in patients with moderate to severe chronic obstructive pulmonary disease

Background

The six-minute walk test (6MWT) is widely used because it is both simple and reliable as a measure of exercise capacity. Individuals with chronic obstructive pulmonary disease (COPD) usually show a limited capacity to perform exercise.

Methods

Our study is a prospective, randomized controlled trial which uses the 6MWT in one hundred consecutive in and out- patients with moderate to severe COPD to assess the benefit of a simple positive expiratory pressure (PEP) device. PEP device consisted of a PEP valve 5 cmH₂O connected to 1-meter tube and a mouthpiece. All the enrolled patients performed a 6MWT before randomization. The following day PEP group patients performed the 6MWT using PEP device. Control group patients performed the 6MWT without this device. The primary outcome was the difference in distance (meters) walked.

Results

Functional capacity assessed by the distance covered during 6MWT improved in the PEP group more than in the control group. The difference was statistically significant (p < 0.001).Oxygen saturation improved to a statistically significant level during 6MWT (p < 0.01). Heart rate was also reduced (p < 0.03).

Conclusions

There are few studies demonstrating that PEP devices enhance exercise capacity in COPD patients. Our results has been obtained using only a low positive expiratory pressure (5 cmH₂O). In our opinion the strength of this study is the simplicity and the lower cost when compared to other devices and approaches. The study was registered as Chi CTR-ORC-12002173 at http://www.chictr.org.

Additive effects of non-invasive ventilation to hyperoxia on cerebral oxygenation in COPD patients with exercise-related O2 desaturation

BACKGROUND

It is currently unknown whether potential haemodynamic improvements induced by non-invasive ventilation (NIV) would positively impact upon cerebral oxygenation (COx) in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD).

OBJECTIVE

To investigate the effects of NIV on exercise COx in COPD patients presenting with exercise-related O(2) desaturation.

METHODS

On a double-blind trial, 13 males (FEV1 = 48·8 ± 15·1% predicted) were randomly assigned to NIV (16 cmH(2)O IPS and 5 cmH(2)O PEEP) plus HOx (FiO(2) = 0·4) or sham NIV (7 cmH(2)O IPS and 5 cmH(2)O PEEP to overcome breathing circuit resistance) plus HOx during ramp-incremental exercise performed on different days. Near-infrared spectroscopy and impedance cardiography assessed changes (Δ) in COx and cardiac output (Q(T)), respectively.

RESULTS

There were no significant between-intervention differences in peak work rate, ventilation and reported symptoms (P>0·05). Peripheral oxyhaemoglobin saturation remained above 98% throughout the tests. NIV + HOx was associated with larger increases in Δ COx, Δ Q(T) and Δ stroke volume at maximal and submaximal exercise (P<0·05). Increases in the area under the curve (to an iso-work rate) of Δ COx under NIV + HOx were significantly (P<0·01) correlated with improvements in Δ Q(T) (r = 0·82) and Δ stroke volume (r = 0·87). There was, however, no significant correlation between enhancement in these physiological responses with changes in peak work rate with NIV + HOx (P>0·05).

CONCLUSIONS

NIV added benefit to HOx in improving central haemodynamics and COx in O(2) 'desaturators' with COPD. The clinical relevance of such beneficial effects on exercise tolerance, however, remains to be demonstrated.

Mechanisms of non-pharmacologic adjunct therapies used during exercise in COPD

Individuals with chronic obstructive pulmonary disease (COPD) are often limited in their ability to perform exercise due to a heightened sense of dyspnea and/or the occurrence of leg fatigue associated with a reduced ventilatory capacity and peripheral skeletal muscle dysfunction, respectively. Pulmonary rehabilitation programs have been shown to improve exercise tolerance and health related quality of life. Additional therapeutic approaches such as non-invasive ventilatory support (NIVS), heliox (He-O(2)) and supplemental oxygen have been used as non-pharmacologic adjuncts to exercise to enhance the ability of patients with COPD to exercise at a higher exercise-intensity and thus improve the physiological benefits of exercise. The purpose of the current review is to examine the pathophysiology of exercise limitation in COPD and to explore the physiological mechanisms underlying the effect of the adjunct therapies on exercise in patients with COPD. This review indicates that strategies that aim to unload the respiratory muscles and enhance oxygen saturation during exercise alleviate exercise limiting factors and improve exercise performance in patients with COPD. However, available data shows significant variability in the effectiveness across patients. Further research is needed to identify the most appropriate candidates for these forms of therapies.