Impact of Non-Invasive Ventilation on Sympathetic Nerve Activity in Chronic Obstructive Pulmonary Disease

Effective non-invasive ventilation reduces muscle sympathetic nerve activity in patients with stable hypercapnic COPD

Increased sympathetic drive is of prognostic significance in chronic obstructive pulmonary disease (COPD) but its determinants remain poorly understood. One potential mechanism may be chemoreflex-mediated adrenergic stimulation caused by sustained hypercapnia. This study determined the impact of non-invasive ventilation (NIV) on muscle sympathetic nerve activity (MSNA) in patients with stable hypercapnic COPD. Ten patients (age 70 ± 7 years, GOLD stage 3-4) receiving long-term NIV (mean inspiratory positive airway pressure 21 ± 7 cmH2O) underwent invasive MSNA measurement via the peroneal nerve during spontaneous breathing and NIV. Compared with spontaneous breathing, NIV significantly reduced hypercapnia (PaCO2 51.5 ± 6.9 vs 42.6 ± 6.1 mmHg, p < 0.0001) along with the burst rate (64.4 ± 20.9 vs 59.2 ± 19.9 bursts/min, p = 0.03) and burst incidence (81.7 ± 29.3 vs 74.1 ± 26.9 bursts/100 heartbeats, p = 0.04) of MSNA. This shows for the first time that correcting hypercapnia with NIV decreases MSNA in COPD.

The effect of a pressure ventilatory support on quadriceps endurance is maintained after exercise training in severe COPD patients. A longitudinal randomized, cross over study

Purpose: In severe chronic obstructive pulmonary disease (COPD) patients, the application of an inspiratory pressure support (IPS) during exercise increases exercise tolerance and the benefit of exercise training during pulmonary rehabilitation (PR). Moreover, it improves quadriceps endurance after a session of cycling exercise suggesting a reduced muscle fatigue. We looked for the persistence of this effect after PR and sought an association between the improved quadriceps endurance with IPS and the training load during PR.

Patients and methods: We studied 20 patients with severe COPD (6 in stage 3and 14 in stage 4 of GOLD) before and after PR. As part of a PR program, patients completed 16 cycling sessions over 6 weeks with the addition of IPS during exercise. As a surrogate of muscular fatigue, quadriceps endurance was measured at 70% of maximal strength in a control condition, after a constant work rate exercise test (CWR) with IPS (TlimQ IPS) or with a sham ventilation (TlimQsham), in a random order. These tests were repeated similarly at the end of PR.

Results: PR was associated with a significant increase in maximal power output, cycling endurance, quadriceps strength and endurance. Session training load (power output x duration of the session) increased by 142% during the course of the program. Before PR, CWR duration increases with IPS compared to sham ventilation (Δtime = +244s, p = 0.001). Compared to control condition, post-exercise TlimQ reduction was lower with IPS at isotime than at the end of CWR or than with sham ventilation (−9 ± 21%, −18 ± 16% and −23 ± 18%, respectively, p = 0.09, p &lt; 0.0001 and p &lt; 0.0001). After PR, the post-exercise decrease of TlimQ was reduced after IPS compared to sham (−9 ± 18% vs. −21 ± 17%, respectively, p = 0.004). No relationship was found between the prevention of quadriceps fatigue and the training load.

Conclusion: In severe COPD patients, the beneficial effect of a ventilator support on quadriceps endurance persisted after PR with IPS. However, it was not related to the increase in training load, and could not predict the training response to non-invasive ventilation during exercise.

Noninvasive ventilation acutely improves endothelial function in exacerbated COPD patients

PURPOSE

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is associated with an elevated risk of cardiovascular events, which can be linked to endothelial dysfunction. In this study, we aimed to investigate whether noninvasive ventilation (NIV) acutely changes endothelial function in hospitalized AECOPD patients.

METHODS

Twenty-one AECOPD patients were assessed in a hospital ward setting from 24 to 48 h after admission. NIV was applied using a ventilator with bilevel pressure support. Before and after NIV protocol, patients were evaluated regarding (1) endothelium-dependent function, assessed non-invasively using the flow-mediated dilation (FMD) method; (2) arterial blood gas analysis. Other baseline evaluations included clinical and anthropometric data, and laboratory tests.

RESULTS

The total group showed a significant improvement in FMD as a result of NIV effect (P = 0.010). While arterial carbon dioxide and oxygen were not altered, oxygen saturation increased after NIV (P = 0.045). The subgroup comparison of responders (FMD ≥ 1%) and non-responders (FMD < 1%) showed significant baseline differences in body mass index (BMI) (P = 0.019) and predicted forced expiratory volume in one second (FEV₁) (P = 0.007). In univariate and multivariate analyses, both BMI and FEV₁ were determinant for endothelial response to NIV.

CONCLUSION

NIV acutely improves endothelial function in hospitalized AECOPD patients. Overweight and COPD severity may represent important characteristics for the magnitude of peripheral vascular response.

Immediate changes in hemodynamics and gas exchange after initiation of noninvasive ventilation in cardiac surgical patients

Introduction

Cardiac surgery is associated with pulmonary dysfunction and complications such as prolonged intubation and reintubation. Bilevel positive airway pressure (BiPAP) machine has been used in the clinical settings to improve oxygenation, reduce work of breathing, and avoid reintubation. The effect of BiPAP on cardiovascular parameters is not well established, and very few studies have targeted hemodynamic changes. The aim of the study was to assess the immediate effect of BiPAP on respiratory and hemodynamic parameters in post-cardiac surgery patients.

Materials and Methods

This quasi-experimental study was done on 33 adult cardiac surgery patients. Ethical review committee approval was sought and consent was taken. All patients who were in respiratory distress with respiratory rate of >30/min and/or PaO₂:FiO₂ ratio of <200 were included. Hemodynamic and respiratory parameters were recorded just before and 15 min after BiPAP application. Sample size was determined on the basis of BiPAP effect on one of the variables, PaO₂:FiO₂ ratio.

Results

A total of 33 patients were included in the study. The average age of the patients was 60.97 ± 10.8, of which 23 (69.7%) were males and 10 (30.7%) females. BiPAP application leads to statistically significant improvement in ventilator parameters including SaO₂ 29 (87.7%), PaO₂ 29 (87.8%), PaCO₂ 21 (63.6%), and PaO₂:FiO₂ ratio in 27 (81.8%).

Conclusion

Ventilatory parameters were significantly improved after BiPAP application in this study, but hemodynamic parameters showed no statistically significant change. BiPAP application was also able to decrease the need for reintubation in post-cardiac surgery patients.

Clinical presentation and comorbidities of obstructive sleep apnea-COPD overlap syndrome

Background

More advanced knowledge is needed on how COPD alters the clinical presentation of obstructive sleep apnea (OSA) and how the association of both diseases, known as ‘overlap syndrome’ (OVS), impacts on cardiovascular health.

Objective

To investigate differences between patients with OVS and those with moderate-to-severe OSA alone.

Methods

A cross-sectional study conducted in the French National Sleep Apnea Registry between January 1997 and January 2017. Univariable and multivariable logistic regression models were used to compare OVS versus OSA alone on symptoms and cardiovascular health.

Results

46,786 patients had moderate-to-severe OSA. Valid spirometry was available for 16,466 patients: 14,368 (87%) had moderate-to-severe OSA alone and 2098 (13%) had OVS. A lower proportion of OVS patients complained of snoring, morning headaches and excessive daytime sleepiness compared to OSA alone (median Epworth Sleepiness Scale score: 9 [interquartile range (IQR) 6–13] versus 10 (IQR 6–13), respectively; P <0.02). Similarly, a lower proportion of OVS patients (35.6% versus 39.4%, respectively; P <0.01) experienced sleepiness while driving. In contrast, 63.5% of the OVS population experienced nocturia compared to 58.0% of the OSA population (P<0.01). Apnea hypopnea index (36 [25; 52] vs 33.1 [23.3; 50]), oxygen desaturation index (28 [15; 48] vs 25.2 [14; 45]) and mean nocturnal SaO2 (92 [90; 93.8] vs 93 [91.3; 94]) were significantly more altered in the OVS group. Associated COPD had no effect on the prevalence of hypertension and stroke. After controlling for main confounders, COPD severity was associated in a dose-response relationship with a higher prevalence of coronary heart disease, heart failure and peripheral arteriopathy.

Conclusions

In adults with moderate-to-severe OSA, OVS was minimally symptomatic, but exhibited higher odds for prevalent coronary heart disease, heart failure and peripheral arteriopathy.

Handgrip Strength and Pulmonary Disease in the Elderly: What is the Link?

Societies in developed countries are aging at an unprecedented rate. Considering that aging is the most significant risk factor for many chronic lung diseases (CLDs), understanding this process may facilitate the development of new interventionist approaches. Skeletal muscle dysfunction is a serious problem in older adults with CLDs, reducing their quality of life and survival. In this study, we reviewed the possible links between handgrip strength (HGS)—a simple, noninvasive, low-cost measure of muscle function—and CLDs in the elderly. Different mechanisms appear to be involved in this association, including systemic inflammation, chronic hypoxemia, physical inactivity, malnutrition, and corticosteroid use. Respiratory and peripheral myopathy, associated with muscle atrophy and a shift in muscle fiber type, also seem to be major etiological contributors to CLDs. Moreover, sarcopenic obesity, which occurs in older adults with CLDs, impairs common inflammatory pathways that can potentiate each other and further accelerate the functional decline of HGS. Our findings support the concept that the systemic effects of CLDs may be determined by HGS, and HGS is a relevant measurement that should be considered in the clinical assessment of the elderly with CLDs. These reasons make HGS a useful practical tool for indirectly evaluating functional status in the elderly. At present, early muscle reconditioning and optimal nutrition appear to be the most effective approaches to reduce the impact of CLDs and low muscle strength on the quality of life of these individuals. Nonetheless, larger in-depth studies are needed to evaluate the link between HGS and CLDs.

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.

Association patterns for size-fractioned indoor particulate matter and black carbon and autonomic function differ between patients with chronic obstructive pulmonary disease and their healthy spouses

BACKGROUND

The effect of health status on the relationship between particulate matter (PM) and black carbon (BC) and cardiac autonomic function has not been examined sufficiently directly comparing patients with healthy participants.

OBJECTIVES

To evaluate the association patterns between size-fractioned indoor PM and BC and cardiac autonomic function in chronic obstructive pulmonary disease (COPD) patients and their healthy spouses.

METHODS

Twenty-four-hour heart rate variability (HRV) and heart rate (HR) was measured in eight pairs of stable COPD patients and their healthy spouses. Real-time size-fractioned indoor PM and BC levels were monitored on the same, and preceding, days. Mixed-effects models were used to estimate the changes in health indices and pollutants after controlling for potential confounding variables.

RESULTS

Increases in size-fractioned PM and BC were associated with alterations in cardiac autonomic function in both COPD patients and their healthy spouses. However, the association patterns differed between the two groups. In COPD group, an IQR (13.65 μg/m³) increase in PM_0.5 at 12-h moving average was associated with reductions of 14.62% (95% CI: -21.74%, -6.86%) in total power (TP) and 10.14% (95% CI: -16.11%, -3.76%) in high frequency (HF) power. In healthy volunteers, however, TP and HF declined immediately upon exposure to PM and then returned to normal levels gradually. In this group, an IQR increase in PM_0.5 at 5 min moving average was associated a 20.30% (95% CI: -25.49%, -14.73%) reduction in TP and a 31.79% (95% CI: -36.48%, -26.72%) reduction in HF.

CONCLUSIONS

Exposure to indoor PM and BC was associated with cardiac autonomic dysfunction in COPD patients and their healthy spouses. Exposure had a greater lagged effect on HRV in COPD patients than in healthy participants. These findings will aid the formulation of targeted measures to prevent the adverse effects of indoor air pollution for individuals with different health statuses.

Voluntary apnea during dynamic exercise activates the muscle metaboreflex in humans

Voluntary apnea during dynamic exercise evokes marked bradycardia, peripheral vasoconstriction, and pressor responses. However, the mechanism(s) underlying the cardiovascular responses seen during apnea in exercising humans is unknown. We therefore tested the hypothesis that the muscle metaboreflex contributes to the apnea-induced pressor response during dynamic exercise. Thirteen healthy subjects participated in apnea and control trials. In both trials, subjects performed a two-legged dynamic knee extension exercise at a workload that elicited heart rates at ~100 beats/min. In the apnea trial, after reaching a steady state, subjects began voluntary apnea. Immediately after cessation of the apnea, arterial occlusion was initiated at both thighs and the subjects stopped exercising. The occlusion was sustained for 3 min in the postexercise period. In the control trial, the occlusion was started without subjects performing the apnea. The apnea induced marked bradycardia, pressor responses, and decreases in arterial O₂ saturation, cardiac output, and total vascular conductance. In addition, arterial blood pressure was significantly higher and total vascular conductance was significantly lower in the apnea trials than the control trials throughout the occlusion period. In separate sessions, we measured apnea-induced changes in exercising leg blood flow in the same subjects. Leg blood flow was significantly reduced by apnea and reached the resting level at the peak of the apnea response. We conclude that the muscle metaboreflex is activated by the decrease in O₂ delivery to the working muscle during apnea in exercising humans and contributes to the large pressor response. NEW & NOTEWORTHY We demonstrated that apnea during dynamic exercise activates the muscle metaboreflex in humans. This result indicates that a reduction in O₂ delivery to working muscle triggers the muscle metaboreflex during apnea. Activation of the muscle metaboreflex is one of the mechanisms underlying the marked apnea-induced pressor response.

The Use of Non-invasive Ventilation during Exercise Training in COPD Patients

Non-invasive ventilation (NIV) is increasingly used in addition to exercise training in patients with chronic obstructive pulmonary disease with the purpose to allow them to train at higher intensities. Different modalities of assisted ventilation have been used with benefits for relief of dyspnoea and increase in exercise capacity. Nevertheless there are some potential problems with the use of NIV in pulmonary rehabilitation programmes. Despite promising results, a generalised use of NIV during exercise training programmes is unlikely to have a role in routine settings. The use of NIV during exercise training as a component of pulmonary rehabilitation should be reserved to individual cases.