Effect of lung volume reduction surgery on resting pulmonary hemodynamics in severe emphysema

Higher small pulmonary artery and vein volume on computed tomography is associated with mortality in current and former smokers

BACKGROUND

In chronic obstructive pulmonary disease (COPD), vascular alterations have been shown to contribute to hypoxia and pulmonary hypertension, but the independent contribution of small vessel abnormalities to mortality remains unclear.

METHODS

We quantified artery and vein dimensions on computed tomography (CT) down to 0.2 mm. Small vessel volumes (<1 mmᴓ) were normalized by body surface area. In 7903 current and former smokers of the COPDGene study (53.2% male) the independent contribution of small artery and small vein volume to all-cause mortality was tested in multivariable Cox models. Additionally, we calculated the 95th percentile of small arteries and veins in 374 never smokers to create two groups: normal and high small artery or vein volume. We describe clinical, physiological and imaging characteristics of subjects with a high small artery and high small vein volume.

FINDINGS

Both high small artery and high small vein volumes were independently associated with mortality with an adjusted hazard ratio of 1.07 [1.01, 1.14] and 1.34 [1.21, 1.49] per mL/m2 increase, respectively. In COPDGene, 447 (5.7%) had high small artery volume and 519 (9.1%) subjects had high small vein volume and both had more emphysema, more air trapping and more severe coronary calcium.

INTERPRETATION

In smokers, abnormally high volumes in small arteries and veins are both relevant for mortality, which urges investigations into the aetiology of small pulmonary vessels and cardiac function in smokers.

FUNDING

Award Number U01-HL089897 and U01-HL089856 from the NHLBI. COPD Foundation with contributions from AstraZeneca, Boehringer Ingelheim, Genentech, GlaxoSmithKline, Novartis, Pfizer, Siemens, and Sunovion.

By deflating the lungs pulmonologists help the cardiologists. A literature review

In this review, we present the effects of lung hyperinflation on the cardiovascular system (CVS) and the beneficial outcomes of different deflation treatment modalities. We discuss the effects of long-acting bronchodilator drugs, medical and surgical lung volume reduction on the performance of the CVS. Although there is a small number of studies investigating lung deflation and the CVS, the short-term improvement in heart function was clearly demonstrated. However, more studies, with longer duration, are needed to verify these significant beneficial effects of deflation of the lungs on the CVS. Dynamic hyperinflation during exercise could be a research model to investigate further the effects of lung hyperinflation and/or deflation on the CVS.

COPD: Providing the right treatment for the right patient at the right time

Chronic Obstructive Pulmonary Disease (COPD) is a common disease associated with significant morbidity and mortality that is both preventable and treatable. However, a major challenge in recognizing, preventing, and treating COPD is understanding its complexity. While COPD has historically been characterized as a disease defined by airflow limitation, we now understand it as a multi-component disease with many clinical phenotypes, systemic manifestations, and associated co-morbidities. Evidence is rapidly emerging in our understanding of the many factors that contribute to the pathogenesis of COPD and the identification of "early" or "pre-COPD" which should provide exciting opportunities for early treatment and disease modification. In addition to breakthroughs in our understanding of the origins of COPD, we are optimizing treatment strategies and delivery of care that are showing impressive benefits in patient-centered outcomes and healthcare utilization. This special issue of Respiratory Medicine, "COPD: Providing the Right Treatment for the Right Patient at the Right Time" is a summary of the proceedings of a conference held in Stresa, Italy in April 2022 that brought together international experts to discuss emerging evidence in COPD and Pulmonary Rehabilitation in honor of a distinguished friend and colleague, Claudio Ferdinando Donor (1948-2021). Claudio was a true pioneer in the field of pulmonary rehabilitation and the comprehensive care of individuals with COPD. He held numerous leadership roles in in the field, provide editorial stewardship of several respiratory journals, authored numerous papers, statement and guidelines in COPD and Pulmonary Rehabilitation, and provided mentorship to many in our field. Claudio's most impressive talent was his ability to organize spectacular conferences and symposia that highlighted cutting edge science and clinical medicine. It is in this spirit that this conference was conceived and planned. These proceedings are divided into 4 sections which highlight crucial areas in the field of COPD: (1) New concepts in COPD pathogenesis; (2) Enhancing outcomes in COPD; (3) Non-pharmacologic management of COPD; and (4) Optimizing delivery of care for COPD. These presentations summarize the newest evidence in the field and capture lively discussion on the exciting future of treating this prevalent and impactful disease. We thank each of the authors for their participation and applaud their efforts toward pushing the envelope in our understanding of COPD and optimizing care for these patients. We believe that this edition is a most fitting tribute to a dear colleague and friend and will prove useful to students, clinicians, and researchers as they continually strive to provide the right treatment for the right patient at the right time. It has been our pleasure and a distinct honor to serve as editors and oversee such wonderful scholarly work.

Lung Volume Reduction Surgery Reduces Pulmonary Arterial Hypertension Associated With Severe Lung Emphysema and Hypercapnia

Lung volume reduction surgery (LVRS) represents a standard surgical approach for patients with severe pulmonary emphysema. One of the relevant risk factors for LVRS is the presence of pulmonary arterial hypertension (PAH). The aim of this study is to assess the postoperative changes in pulmonary arterial pressure (PAP) after LVRS for patients with severe pulmonary emphysema compared with preoperative measures. N = 61 consecutive patients with severe pulmonary emphysema and preoperative evidence for PAH (pulmonary arterial systolic pressure [PASP] ≥ 35 mmHg) were prospectively included into this study. In all patients, thoracoscopic LVRS was performed. PASP was assessed by echocardiography before surgery, early postoperatively, and 3 months after surgery. Data were prospectively recorded and analyzed retrospectively. Primary end points were the postoperative changes in PASP as well as the 90 day mortality rate. Secondary endpoints included: pulmonary function test, exercise capacity, quality of life, and dyspnea symptoms (Borg scale). Early after surgery, a significant reduction in PASP was observed at the day of discharge and at 3 month follow-up. In n = 34 patients, no tricuspid valve regurgitation was detectable anymore suggesting normal PAP. In n = 3 patients, venovenous extracorporeal lung support (VV ECLS) was already implemented preoperatively. In the remaining cases, VV ECLS was applied intraoperatively and continued postoperatively. Mean duration of postoperative ECLS support was 2 days. Four patients died due to acute right heart failure, two patients from sepsis with multiorgan failure, and one patient from acute pulmonary embolism. Ninety day mortality was 11.5 %. A significant improvement was postoperatively observed regarding the performance status, dyspnea scale, as well as quality of life. This study suggests a beneficial effect of LVRS on PAP, which may ultimately help to protect and stabilize right ventricular function. Further studies, implementing pre- and postoperative right heart catheterizations including invasive PAP evaluation, are necessary to support the findings in this study in greater detail.

Lung Disease-Related Pulmonary Hypertension

Patients with advanced lung disease can develop pulmonary hypertension and succumb to right ventricular failure/cor pulmonale. Patients with pulmonary hypertension owing to chronic lung disease, or World Health Organization group 3 pulmonary hypertension, are more limited and carry a high risk of mortality. Adjunctive therapies remain the cornerstones of treatment. Recent evidence suggests that inhaled pulmonary vasodilator therapy can be helpful in patients with pulmonary hypertension owing to interstitial lung disease. Lung transplantation may be the only life-saving option in select patients, whereas palliative care and hospice should be sought for those who are not candidates as the disease progresses.

The Effects of Endobronchial Coil Therapy on Right Ventricular Functions

Lung hyperinflation is an important therapeutic target in symptomatic emphysema patients. Endobronchial therapies that reduce end-expiratory lung volume are increasingly being used in advanced cases. However, there is paucity of data regarding the effects of these therapies on the heart functions. The aim of this study is to evaluate the right ventricular functions before and after the procedure in patients who underwent endobronchial coil therapy (EBCT).Patients who were between 18 and 80 years of age and scheduled for EBCT with GOLD 3-4 were enrolled in the study. Right heart functions were evaluated using MPI, TAS, TAPSE. Right atrium area and maximum velocity of tricuspid regurgitation were also noted.A total of 23 patients were enrolled in the study. 21 patients underwent bilateral intervention, while only 2 patients received unilateral treatment. There was an improvement in MPI (0.49 ± 0.15 vs 0.39 ± 0.11, p < 0.001) and TAS (11.6 (9 - 15) vs 13.2 (9.80 - 17.0), p = 0.001). Peak TRV (2.52 ± 0.6, 2.38 ± 0.6, p = 0.02) and PASP values were lower in the post-operative period (41.15 ± 5.94 vs 36.83 ± 8.01 p = 0.019).In this current study, we found improved echocardiographic RtV parameters in patients who received EBCT treatment.

Bronchoscopic lung volume reduction: status quo

Emphysema is associated with irreversible loss of lung compliance leading to gas trapping and hyperinflation. Surgical lung volume reduction has proven to improve lung function, exercise capacity, cardiac health and survival in patients with advanced emphysema; however, this procedure is associated with significant morbidity and mortality. Bronchoscopic lung volume reduction (BLVR) has emerged as an alternative approach for these patients. In this article, we review the different techniques used for the purpose of this procedure, its advantages and disadvantages. In addition, we discuss in length valve therapy and the studies that led to its recent FDA approval. Finally, we provide thought-provoking challenges that may be topics for further future investigation to enhance the efficacy and benefit of this technique.

The effects of lung volume reduction treatment on diffusing capacity and gas exchange

Lung volume reduction (LVR) treatment in patients with severe emphysema has been shown to have a positive effect on hyperinflation, expiratory flow, exercise capacity and quality of life. However, the effects on diffusing capacity of the lungs and gas exchange are less clear. In this review, the possible mechanisms by which LVR treatment can affect diffusing capacity of the lung for carbon monoxide (D _LCO) and arterial gas parameters are discussed, the use of D _LCO in LVR treatment is evaluated and other diagnostic techniques reflecting diffusing capacity and regional ventilation (V')/perfusion (Q') mismatch are considered.A systematic review of the literature was performed for studies reporting on D _LCO and arterial blood gas parameters before and after LVR surgery or endoscopic LVR with endobronchial valves (EBV). D _LCO after these LVR treatments improved (40 studies, n=1855) and the mean absolute change from baseline in % predicted D _LCO was +5.7% (range -4.6% to +29%), with no real change in blood gas parameters. Improvement in V' inhomogeneity and V'/Q' mismatch are plausible explanations for the improvement in D _LCO after LVR treatment.

Lung Volume Reduction Surgery in Patients with Heterogenous Emphysema: Selecting Perspective

BACKGROUND:

Lung volume reduction surgery (LVRS) was introduced to alleviate clinical conditions in selected patients with heterogenous emphysema. Clarifying the most suitable patients for LVRS remained unclear.

AIM:

This study was undertaken to specifically analyze the preoperative factor affecting to LVRS.

METHODS:

The prospective study was conducted at 103 Military Hospital between July 2014 and April 2016. Severe heterogenous emphysema patients were selected to participate in the study. The information, spirometry, and body plethysmographic pulmonary function tests in 31 patients who underwent LVRS were compared with postoperative outcomes (changing in FEV1 and CAT scale).

RESULTS:

Of the 31 patients, there was statistically significant difference in the outcome of functional capacity, lung function between two groups (FEV1 ≤ 50% and > 50%) (∆FEV1: 22.46 vs 18.32%; p = 0.042. ∆ CAT: 6.85 vs 5.07; p = 0.048). Changes of the FEV1 and CAT scale were no statistically significant differences in three groups residual volume. Patients with total lung capacity < 140% had more improved than others (∆FEV1: 23.81 vs 15.1%; p = 0.031).

CONCLUSION:

Preoperative spirometry and body plethysmographic pulmonary function tests were useful measures to selected severe heterogenous emphysema patients for LVRS. Patients with FEV1 ≤ 50%, TLC in the range of 100-140% should be selected.

Assessing pulmonary hypertension in COPD. Is there a role for computed tomography?

Pulmonary hypertension (PH) is a common complication of chronic obstructive pulmonary disease (COPD) and is associated with increased morbidity and mortality. Reference standard method to diagnose PH is right heart catheterization. Several non-invasive imaging techniques have been employed in the detection of PH. Among them, computed tomography (CT) is the most commonly used for phenotyping and detecting complications of COPD. Several CT findings have also been described in patients with severe PH. Nevertheless, CT analysis is currently based on visual findings which can lead to reproducibility failure. Therefore, there is a need for quantification in order to assess objective criteria. In this review, progresses in automated analyses of CT parameters and their values in predicting PH and COPD outcomes are presented.

Lung volume reduction surgery in selected patients with emphysema and pulmonary hypertension

OBJECTIVES

Pulmonary hypertension (PH) is considered a contraindication for lung volume reduction surgery (LVRS). Because, it has been reported that endobronchial lung volume reduction may have a beneficial effect without increased mortality in patients with emphysema and PH, we evaluated its effect on PH in patients undergoing LVRS.

METHODS

From January 2014 until June 2016, 119 LVRSs were performed at Zurich University Hospital. PH was a contraindication for patients with homogeneous emphysema but was acceptable for those with heterogeneous emphysema. Thirty patients underwent echocardiography before and after LVRS, 10 of whom had preoperative systolic pulmonary artery pressures >35 mmHg and 20 of whom had normal systolic pulmonary artery pressure. The effect of LVRS on pulmonary artery pressure, lung function and survival was analysed.

RESULTS

Ninety-day mortality for all 30 patients was 0, and the postoperative course did not differ significantly between the 2 groups. In patients with PH, the median systolic pulmonary artery pressure decreased from 41 mmHg [interquartile range (IQR) 39-47] to 37 mmHg (IQR 36-38, P = 0.04). These patients had an improvement of forced expiratory volume in 1 s from the median 27% predicted (IQR 23-34) to 33% (IQR 28-40, P = 0.007) 3 months postoperatively.

CONCLUSIONS

If further confirmed in other cohorts, mild to moderate PH may no longer be considered a contraindication for LVRS in patients with heterogeneous emphysema.

Lung volume reduction followed by lung transplantation-considerations on selection criteria and outcome

Lung transplantation (LuTX) and lung volume reduction (LVR), either surgical (LVRS: lung volume reduction surgery) or endoscopic (ELVR: endoscopic lung volume reduction), are established therapies in the treatment of end-stage chronic obstructive pulmonary disease (COPD) patients. Careful patient selection is crucial for each intervention. If these techniques are sequentially applied there is a paucity of available data and individual center experiences vary depending on details in selection criteria and operative technique. This review aims to summarize the published data with a focus on LuTX after LVRS. This review covers patient selection for LuTX and LVR, technical considerations, limitations and outcomes. Published literature was identified by systematic search on Medline and appropriate papers were reviewed. Seven case reports/series, 7 comparative observational studies and one multicenter database analysis incorporating a total of 284 patients with LuTX and LVR were evaluated. Prior LVR can significantly affect intraoperative and postoperative risks after subsequent LuTX. Careful patient selection and timing and the choice of appropriate techniques such as minimal invasive LVRS and using ECMO as extracorporeal support during LuTX if required can minimize those risks, ultimately leading to very good postoperative outcomes in terms of lung function and survival. LVRS has the potential to delay listing and to bridge patients to LuTX by improving their physical condition while on the waiting list. After single lung transplantation (SLuTX) contralateral LVRS can counteract the deleterious effects of native lung hyperinflation (NLH). LVR and LuTX are adjunct therapies in the treatment of end-stage COPD. The combination of both can safely be considered in selected patients.

Pulmonary hypertension in chronic obstructive pulmonary disease and emphysema patients: prevalence, therapeutic options and pulmonary circulatory effects of lung volume reduction surgery

The exact prevalence of pulmonary hypertension (PH) and cor pulmonale (CP) in chronic obstructive pulmonary disease (COPD) is unknown, and varies considerably from 20-91%. Usually, mean pulmonary artery pressure (mPAP) does not exceed 30 mmHg, and PH is not severe. However, PH and CP are important predictors of mortality in COPD and contribute to disability in this disease. Many factors contribute to the development of PH in chronic lung disease, including reduction of the pulmonary vascular cross-sectional area due to parenchymal loss and accompanying hypoxia, effects of abnormal pulmonary mechanics due to hyperinflation, but also vascular remodeling processes. So far, PH associated with chronic lung disease cannot be treated medically. Therefore, it is indicated to treat the underlying pulmonary disease. Patients with severe PH should be referred to centers experienced in the management of PH and enrollment in clinical trials should be considered. Lung volume reduction surgery (LVRS) theoretically further increases pulmonary vascular resistance (PVR) by reducing the vascular bed when resecting lung tissue, however, this might be compensated by better pulmonary mechanics through reduction of hyperinflation, which will be discussed in the present article.

Lung volume reduction surgery or bronchoscopic lung volume reduction: is there an algorithm for allocation?

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the world with the annual number of deaths increasing every year. Alterations in chest wall mechanics, respiratory muscle mechanics, and impaired cardiac function that result from increased air-trapping are well known sequelae of COPD and contribute to increased morbidity and mortality. A reduction in hyperinflation can improve cardiopulmonary function. In selected patients with COPD and an emphysema phenotype, lung volume reduction surgery (LVRS) has demonstrated improvements in symptom burden and mortality. Minimally invasive bronchoscopic techniques that reduce end-expiratory lung volume have shown improvements in lung function, dyspnea and quality of life. In this review, we review selection criteria, risks, and benefits of surgical and bronchoscopic lung volume reduction (BLVR). Recommendations are provided to guide treatment decisions based on the current literature.

The Link between Reduced Inspiratory Capacity and Exercise Intolerance in Chronic Obstructive Pulmonary Disease

Low inspiratory capacity (IC), chronic dyspnea, and reduced exercise capacity are inextricably linked and are independent predictors of increased mortality in chronic obstructive pulmonary disease. It is no surprise, therefore, that a major goal of management is to improve IC by reducing lung hyperinflation to improve respiratory symptoms and health-related quality of life. The negative effects of lung hyperinflation on respiratory muscle and cardiocirculatory function during exercise are now well established. Moreover, there is growing appreciation that a key mechanism of exertional dyspnea in chronic obstructive pulmonary disease is critical mechanical constraints on tidal volume expansion during exercise when resting IC is reduced. Further evidence for the importance of lung hyperinflation comes from multiple studies, which have reported the clinical benefits of therapeutic interventions that reduce lung hyperinflation and increase IC. A reduced IC in obstructive pulmonary disease is further eroded by exercise and contributes to ventilatory limitation and dyspnea. It is an important outcome for both clinical and research studies.

Effective Bronchoscopic Lung Volume Reduction Accelerates Exercise Oxygen Uptake Kinetics in Emphysema

BACKGROUND

The impact of bronchoscopic lung volume reduction (BLVR) on physiologic responses to exercise in patients with advanced emphysema remains incompletely understood. We hypothesized that effective BLVR (e-BLVR), defined as a reduction in residual volume > 350 mL, would improve cardiovascular responses to exercise and accelerate oxygen uptake (Vo₂) kinetics.

METHODS

Thirty-one patients (FEV1, 36% ± 9% predicted; residual volume, 219% ± 57% predicted) underwent a constant intensity exercise test at 70% peak work rate to the limit of tolerance before and after treatment bronchoscopy (n = 24) or sham bronchoscopy (n = 7). Physiologic responses in patients who had e-BLVR (n = 16) were compared with control subjects (ineffective BLVR or sham bronchoscopy; n = 15).

RESULTS

e-BLVR reduced residual volume (-1.1 ± 0.5 L, P = .001), improved lung diffusing capacity by 12% ± 13% (P = .001), and increased exercise tolerance by 181 ± 214 s (P = .004). Vo₂ kinetics were accelerated in the e-BLVR group but remained unchanged in control subjects (Δ mean response time, -20% ± 29% vs 1% ± 25%, P = .04). Acceleration of Vo₂ kinetics was associated with reductions in heart rate and oxygen pulse response half-times by 8% (84 ± 14 to 76 ± 15 s, P = .04) and 20% (49 ± 16 to 34 ± 16 s, P = .01), respectively. There were also increases in heart rate and oxygen pulse amplitudes during the cardiodynamic phase post e-BLVR. Faster Vo₂ kinetics in the e-BLVR group were significantly correlated with reductions in residual volume (r = 0.66, P = .005) and improvements in inspiratory reserve volume (r = 0.56, P = .024) and exercise tolerance (r = 0.63, P = .008).

CONCLUSIONS

Lung deflation induced by e-BLVR accelerated exercise Vo₂ kinetics in patients with emphysema. This beneficial effect appears to be related mechanistically to an enhanced cardiovascular response to exercise, which may contribute to improved functional capacity.

Use of outcome measures in pulmonary hypertension clinical trials

OBJECTIVES

To evaluate the use of surrogate measures in pulmonary hypertension (PH) clinical trials and how it relates to clinical practice.

BACKGROUND

Studies of pulmonary arterial hypertension (PAH) employ a variety of surrogate measures in addition to clinical events because of a small patient population, participant burden, and costs. The use of these measures in PH drug trials is poorly defined.

METHODS

We searched PubMed/MEDLINE/Embase for randomized or prospective cohort PAH clinical treatment trials from 1985 to 2013. Extracted data included intervention, trial duration, study design, patient characteristics, and primary and secondary outcome measures. To compare with clinical practice, we assessed the use of surrogate measures in a clinical sample of patients on PH medications at Duke University Medical Center between 2003 and 2014.

RESULTS

Between 1985 and 2013, 126 PAH trials were identified and analyzed. Surrogate measures served as primary endpoints in 119 trials (94.0%). Inclusion of invasive hemodynamics decreased over time (78.6%, 75.0%, 52.2%; P for trend = .02), while functional testing (7.1%, 60.0%, 81.5%; P for trend < .0001) and functional status or quality of life (0%, 47.6%, 62.8%; P for trend < .0001) increased in PAH trials over the same time periods. Echocardiography data were reported as a primary or secondary outcome in 32 trials (25.4%) with increased use from 1985-1994 to 1995-2004 (7.1% vs 35.0%, P = .04), but the trend did not continue to 2005-2013 (25.0%). In comparison, among 450 patients on PAH therapies at our institution between 2003 and 2013, clinical assessments regularly incorporated serial echocardiography and 6-minute walk distance tests (92% and 95% of patients, respectively) and repeat measurement of invasive hemodynamics (46% of patients).

CONCLUSIONS

The majority of PAH trials have utilized surrogate measures as primary endpoints. The use of these surrogate endpoints has evolved significantly over time with increasing use of patient-centered endpoints and decreasing or stable use of imaging and invasive measures. In contrast, imaging and invasive measures are commonly used in contemporary clinical practice. Further research is needed to validate and standardize currently used measures.

[COPD and heart disease]

Cardiovascular diseases are highly prevalent in patients with chronic obstructive pulmonary disease (COPD). Approximately one out of three patients with COPD dies of cardiovascular disease. Overlap syndrome (COPD and obstructive sleep apnea), pulmonary hypertension and lung hyperinflation have a further impact on cardiovascular function in patients with COPD.

Morphologic Response of the Pulmonary Vasculature to Endoscopic Lung Volume Reduction

INTRODUCTION

Endoscopic Lung Volume Reduction has been used to reduce lung hyperinflation in selected patients with severe emphysema. Little is known about the effect of this procedure on the intraparenchymal pulmonary vasculature. In this study we used CT based vascular reconstruction to quantify the effect of the procedure on the pulmonary vasculature.

METHODS

Intraparenchymal vasculature was reconstructed and quantified in 12 patients with CT scans at baseline and 12 weeks following bilateral introduction of sealants in the upper lobes. The volume of each lung and each lobe was measured, and the vascular volume profile was calculated for both lower lobes. The detected vasculature was further labeled manually as arterial or venous in the right lower lobe.

RESULTS

There was an increase in the volume of the lower lobes (3.14L to 3.25L, p=0.0005). There was an increase in BV5, defined as the volume of blood vessels with cross sectional area of less than 5mm², (53.2ml to 57.9ml, p=0.03). This was found to be correlated with the increase in lower lobe volumes (R=0.65, p=0.02). The changes appear to be symmetric for veins and arteries with a correlation coefficient of 0.87 and a slope of near identity.

CONCLUSION

In the subjects studied, there was an increase, from baseline, in BV5 in the lower lobes that correlated with the change in the volume of the lower lobes. The change appeared to be symmetric for both arteries and veins. The study illustrates the use of intraparenchymal pulmonary vascular reconstruction to study morphologic changes in response to interventions.

Quantification of Improvements in Static and Dynamic Ventilatory Measures Following Lung Volume Reduction Surgery for Severe COPD

Rationale: This study quantitatively measured the effects of lung volume reduction surgery (LVRS) on spirometry, static and dynamic lung and chest wall volume subdivision mechanics, and cardiopulmonary exercise measures. Methods: Patients with severe COPD (mean FEV₁ = 23 ± 6% predicted) undergoing LVRS evaluation were recruited. Spirometry, plethysmography and exercise capacity were obtained within 6 months pre-LVRS and again within 12 months post- LVRS. Ventilatory mechanics were quantified using stationary optoelectronic plethysmography (OEP) during spontaneous tidal breathing and during maximum voluntary ventilation (MVV). Statistical significance was set at P< 0.05. Results:Ten consecutive patients met criteria for LVRS (5 females, 5 males, age: 62±6yrs). Post -LVRS (mean follow up 7 months ± 2 months), the group showed significant improvements in dyspnea scores (pre 4±1 versus post 2 ± 2), peak exercise workload (pre 37± 21 watts versus post 50 ± 27watts ), heart rate (pre 109±19 beats per minutes [bpm] versus post 118±19 bpm), duty cycle (pre 30.8 ± 3.8% versus post 38.0 ± 5.7%), and spirometric measurements (forced expiratory volume in 1 second [FEV₁] pre 23 ± 6% versus post 32 ± 13%, total lung capacity / residual lung volume pre 50 ± 8 versus 50 ± 11) . Six to 12 month changes in OEP measurements were observed in an increased percent contribution of the abdomen compartment during tidal breathing (41.2±6.2% versus 44.3±8.9%, P=0.03) and in percent contribution of the pulmonary ribcage compartment during MVV (34.5±10.3 versus 44.9±11.1%, P=0.02). Significant improvements in dynamic hyperinflation during MVV occurred, demonstrated by decreases rather than increases in end expiratory volume (EEV) in the pulmonary ribcage (pre 207.0 ± 288.2 ml versus post -85.0 ± 255.9 ml) and abdominal ribcage compartments (pre 229.1 ± 182.4 ml versus post -17.0 ± 136.2 ml) during the maneuver. Conclusions: Post-LVRS, patients with severe COPD demonstrate significant favorable changes in ventilatory mechanics, during tidal and maximal voluntary breathing. Future work is necessary to determine if these findings are clinically relevant, and extend to other environments such as exercise.

Endoscopic lung volume reduction with endobronchial valves in patients with severe emphysema and established pulmonary hypertension

BACKGROUND

One of the most common forms of pulmonary hypertension (PH) is that associated with chronic obstructive pulmonary disease (COPD). So far, patients with severe emphysema and established PH have been excluded from endoscopic lung volume reduction (ELVR) therapy due to the risk of right heart decompensation.

OBJECTIVE

The aim of this pilot study was to evaluate the feasibility and efficacy of ELVR using one-way endobronchial valves (EBV) in this specific group of patients.

METHODS

We prospectively included 6 patients with COPD, severe heterogeneous emphysema, and established PH who underwent right heart catheterization and clinical assessments before and 90 days after ELVR with unilateral EBV placement.

RESULTS

This study was not powered to measure any statistical differences in endpoints. Ninety days after ELVR, the symptoms, lung function, and hemodynamics improved in 5 out of 6 patients (1 patient normalized and 1 slightly worsened). The mean hemodynamics improved from baseline to 90 days after ELVR as follows: mean pulmonary artery pressure, -2.5 ± 3.5 mm Hg; pulmonary arterial wedge pressure, -4.3 ± 8.3 mm Hg; cardiac index, +0.3 ± 0.6 l/min/m(2), and 6-min walk distance, +59 ± 99 m. ELVR was performed without PH-related complications in all patients.

CONCLUSION

To our knowledge, this is the first prospective, single-center pilot study to evaluate the feasibility and efficacy of ELVR in patients with established PH. ELVR was feasible and resulted in an improvement of clinical and hemodynamic parameters in 5 out of 6 patients. These results have to be further confirmed in larger-scale controlled studies.

Cardiopulmonary coupling in chronic obstructive pulmonary disease: the role of imaging

Chronic obstructive pulmonary disorder (COPD) is a systemic disease that affects the cardiovascular system through multiple pathways. Pulmonary hypertension, ventricular dysfunction, and atherosclerosis are associated with smoking and COPD, causing significant morbidity and poor prognosis. Coupling between the pulmonary and cardiovascular system involves mechanical interdependence and inflammatory pathways that potentially affect the entire circulation. Although treatments specific for COPD-related cardiovascular and pulmonary vascular disease are limited, early diagnosis, study of pathophysiology, and monitoring the effects of treatment are enhanced with improved imaging techniques. In this article, we review recent advancements in the imaging of the vasculature and the heart in patients with COPD. We also explore the potential mechanism of coupling between the progression of COPD and vascular disease. Imaging methods reviewed include specific implementations of computed tomography, magnetic resonance imaging, dual-energy computed tomography, positron emission tomography, and echocardiography. Specific applications to the proximal and distal pulmonary vasculature, as well as to the heart and systemic circulation, are also discussed.

Pulmonary hypertension and right heart dysfunction in chronic lung disease

Group 3 pulmonary hypertension (PH) is a common complication of chronic lung disease (CLD), including chronic obstructive pulmonary disease (COPD), interstitial lung disease, and sleep-disordered breathing. Development of PH is associated with poor prognosis and may progress to right heart failure, however, in the majority of the patients with CLD, PH is mild to moderate and only a small number of patients develop severe PH. The pathophysiology of PH in CLD is multifactorial and includes hypoxic pulmonary vasoconstriction, pulmonary vascular remodeling, small vessel destruction, and fibrosis. The effects of PH on the right ventricle (RV) range between early RV remodeling, hypertrophy, dilatation, and eventual failure with associated increased mortality. The golden standard for diagnosis of PH is right heart catheterization, however, evidence of PH can be appreciated on clinical examination, serology, radiological imaging, and Doppler echocardiography. Treatment of PH in CLD focuses on management of the underlying lung disorder and hypoxia. There is, however, limited evidence to suggest that PH-specific vasodilators such as phosphodiesterase-type 5 inhibitors, endothelin receptor antagonists, and prostanoids may have a role in the treatment of patients with CLD and moderate-to-severe PH.

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.

High Prevalence of Left Ventricle Diastolic Dysfunction in Severe COPD Associated with A Low Exercise Capacity: A Cross-Sectional Study

Background

A subclinical left ventricle diastolic dysfunction (LVDD) has been described in patients with chronic obstructive pulmonary disease (COPD).

Objectives

To evaluate the prevalence of LVDD in stable severe COPD patients, to analyze its relationship with exercise capacity and to look for its possible causes (lung hyperinflation, ventricular interdependence or inflammatory mechanisms).

Methods

We evaluated 106 consecutive outpatients with severe COPD (FEV₁ between 30–50%). Thirty-three (31%) were excluded because of previous heart disease. A pulmonary function test, a 6-minute walking test (6MWT), a Doppler echocardiography test, including diastolic dysfunction parameters, and an analysis of arterial blood gases, NT-proBNP and serum inflammatory markers (CRP, leucocytes), were performed in all patients.

Results

The prevalence of LVDD in severe stable COPD patients was 90% (80% type I, n=57, and 10% type II, n=7). A significant association between a lower E/A ratio (higher LVDD type I) and a lower exercise tolerance (6-minute walked distance (6MWD)) was found (r=0.29, p<0.05). The fully adjusted multivariable linear regression model demonstrated that a lower E/A ratio, a DLCO in the quartile 4^th and a higher tobacco consumption were associated with a lower 6MWD (76, 57 and 0.7 metres, respectively, p<0.05). A significant correlation between E/A ratio and PaO₂ was observed (r=0.26, p<0.05), but not with static lung hyperinflation, inflammation or right ventricle overload parameters.

Conclusion

In stable severe COPD patients, the prevalence of LVDD is high and this condition might contribute in their lower exercise tolerance. Hypoxemia could have a concomitant role in their pathogenesis.

World Health Organization Group III pulmonary hypertension

Pulmonary hypertension in the setting of parenchymal lung disease and conditions associated with chronic hypoxemia is commonly encountered in clinical practice and may adversely affect patients' function and mortality. Diagnosis of this subgroup of pulmonary hypertension has evolved but still requires right heart catheterization for confirmation. The primary treatment goal is optimization of the underlying parenchymal lung or hypoxemia-associated condition prior to consideration of pharmacologic therapy. Limited published experience with pulmonary hypertension-specific medications for treatment of WHO Group 3 pulmonary hypertension suggests symptomatic and functional benefit in selected individuals. The potential for worsening ventilation-perfusion matching must be considered in these cases, however, since there is a paucity of data regarding the optimal approach to treatment selection. Ongoing medication trials and further investigation of mechanisms of hypoxic pulmonary vasoconstriction provide hope for these patients who in the past often had only lung transplantation as a potential treatment option.

Statins, systemic inflammation and risk of death in COPD: the Rotterdam study

BACKGROUND

Studies suggest that statins decrease mortality in COPD patients but it is unknown which patients might benefit most.

OBJECTIVES

We investigated whether statins were associated with reduced mortality in COPD patients and whether effects differed according to baseline high-sensitivity C-reactive protein (hsCRP) concentration, a marker of systemic inflammation.

METHODS

This nested case-control study was part of the Rotterdam Study, a prospective population-based cohort study among 7983 subjects ≥ 55 years. Using automated pharmacy records, we evaluated statin use of 363 cases (COPD patients who died during follow-up of 17 years) with 2345 age and sex matched controls (COPD patients who survived the follow-up period of the index case).

RESULTS

Compared to never use, long-term statin use (>2 years) was associated with a 39% decreased risk of death in COPD patients. Stratified according to the level of systemic inflammation, long-term statin use was associated with a 78% reduced mortality if hsCRP level > 3 mg/L, versus a non significant 21% reduced mortality if hsCRP level ≤ 3 mg/L.

CONCLUSIONS

Statin use is associated with a beneficial effect on all-cause mortality in COPD, depending on the baseline level of systemic inflammation.

Pulmonary Hypertension Secondary to COPD

The development of pulmonary hypertension in COPD adversely affects survival and exercise capacity and is associated with an increased risk of severe acute exacerbations. Unfortunately not all patients with COPD who meet criteria for long term oxygen therapy benefit from it. Even in those who benefit from long term oxygen therapy, such therapy may reverse the elevated pulmonary artery pressure but cannot normalize it. Moreover, the recent discovery of the key roles of endothelial dysfunction and inflammation in the pathogenesis of PH provides the rationale for considering specific pulmonary vasodilators that also possess antiproliferative properties and statins.

Right ventricular dysfunction in chronic lung disease

Right ventricular (RV) dysfunction arises in chronic lung disease when chronic hypoxemia and disruption of pulmonary vascular beds increase ventricular afterload. RV dysfunction is defined by hypertrophy with preserved myocardial contractility and cardiac output. RV hypertrophy seems to be a common complication of chronic and advanced lung disease. RV failure is rare, except during acute exacerbations of chronic lung disease or when multiple comorbidities are present. Treatment is targeted at correcting hypoxia and improving pulmonary gas exchange and mechanics. There are no data supporting the use of pulmonary hypertension-specific therapies for patients with RV dysfunction secondary to chronic lung disease.

The epidemiology of vascular dysfunction relating to chronic obstructive pulmonary disease and emphysema

Cor pulmonale has long been described in very severe chronic obstructive pulmonary disease (COPD) and emphysema. Cross-sectional results from population-based studies show that left ventricular filling and a variety of vascular measures in the systemic circulation are abnormal in preclinical COPD and emphysema and that a predominant vascular change in COPD and emphysema is endothelial and microvascular dysfunction. These findings suggest that pulmonary vascular changes may occur early in COPD and emphysema and might contribute to pathogenesis. However, longitudinal epidemiologic studies with direct measures of the pulmonary vasculature are lacking; therefore, inferences are limited at present. New imaging-based approaches to the assessment of the pulmonary vasculature are applicable to epidemiologic studies and may help in defining the relationship of pulmonary vascular damage to progression of COPD and emphysema. These measures may also provide imaging-based surrogate markers, and novel therapeutics targeted to the pulmonary vasculature might reduce symptoms and improve function in these common diseases.

The National Emphysema Treatment Trial (NETT) Part II: Lessons learned about lung volume reduction surgery

Substantial information regarding the role of lung volume reduction surgery (LVRS) in severe emphysema emanates from the National Emphysema Treatment Trial (NETT). The NETT was not a crossover trial and therefore was able to examine the effects of optimal medical management and LVRS on short- and long-term survival,as well as lung function, exercise performance, and quality of life.The NETT generated multiple insights into the preoperative, perioperative,and postoperative management of patients undergoing thoracotomy; described pain control techniques that were safe and effective; and emphasized the need to address nonpulmonary issues to optimize surgical outcomes. After the NETT, newer investigation has focused on bronchoscopic endobronchial interventions and other techniques less invasive than LVRS to achieve lung reduction.In this review, we summarize what we currently know about the role of LVRS in the treatment of severe emphysema as a result of insights gained from the NETT and provide a brief review of the newer techniques of lung volume reduction.

The National Emphysema Treatment Trial (NETT): Part I: Lessons learned about emphysema

The National Emphysema Treatment Trial (NETT) was a multicenter prospective randomized controlled trial that compared optimal medical treatment, including pulmonary rehabilitation, with optimal medical treatment plus lung volume reduction surgery (LVRS). It was the largest and most complete collection of patient demographic, clinical, physiological, and radiographic data ever compiled in severe emphysema. NETT investigated the effects of optimal medical management and LVRS on short- and long-term survival, as well as lung function, exercise performance, and quality of life. NETT also provided much information regarding the evaluation and prognosis of severe emphysema; specifically the important negative influences that hyperinflation and small airway disease have on survival. NETT emphasized the importance of addressing nonpulmonary issues such as nutrition, cardiac disease, anxiety, and depression in emphysema. NETT demonstrated that physiological, genomic, and radiographic phenotype can predict patient survival as well as response to treatment. Because the major purpose of NETT was to compare bilateral LVRS with optimal medical treatment in emphysema, patients enrolled into NETT were comprehensively characterized and selected to have a specific window of airflow obstruction and hyperinflation and to lack significant comorbidities. The NETT patient population’s restrictive features offer distinct advantages (well-characterized predominant emphysematous phenotype) and disadvantages (lack of comorbidities and significant chronic bronchitis) that must be considered when interpreting the implications of these results. Herein, we provide a summary of the major NETT findings that provide insight into the evaluation and medical treatment of emphysema.

Initial risk assessment for pulmonary hypertension in patients with COPD

BACKGROUND

Pulmonary hypertension (PH) is a comorbidity associated with increased mortality in chronic obstructive pulmonary disease (COPD) patients. It is not known which clinical markers are predictive of PH in COPD. The goal of this study was to develop a clinical tool to identify patients who should be sent for initial screening with echocardiography.

METHODS

Of 127 patients screened, 94 primary-care patients with COPD were enrolled. All underwent full pulmonary function testing, 6-minute walk distance (6MWD), exercise oximetry, Saint George's Respiratory Questionnaire, and transthoracic echocardiography. Eighty-six patients had measurable pulmonary artery pressures (PAP) on echocardiography. Elevated PAP was defined as a systolic PAP > 35 mmHg.

RESULTS

Pre- and post-bronchodilator FEV(1) (P = 0.04 and P = 0.03, respectively), exercise oxyhemoglobin desaturation (P = 0.003), and 6MWD (P = 0.004) were associated with elevated PAP on univariate analysis. Diffusion capacity was lower but did not reach statistical significance (P = 0.07). In multivariate analysis, statistically significant independent variables were >3% decrease in exercise oxyhemoglobin saturation and decline in prebronchodilator FEV(1) (P = 0.01 and P = 0.04, respectively). A composite prediction model was developed that assigned one point for each of the following: age > 55 years, oxyhemoglobin desaturation > 3%, prebronchodilator FEV(1) < 50% predicted, and 6MWD < 1175 ft. Prevalence rates of elevated PAP were 32% for a score of 0-1 (low risk), 68% for a score of 2 (moderate risk), and 78% for a score of 3-4 (high risk). The composite score exhibited a strong trend with elevated PAP prevalence (Cochrane-Armitage trend statistic P = 0.001).

CONCLUSION

A simple prediction tool using routine office-based parameters can be used to identify COPD patients at high risk for elevated PAP and initiate the first step in screening for PH with echocardiography. It is important that right heart catheterization be performed to confirm the diagnosis and guide treatment decisions.

Lung deflation and oxygen pulse in COPD: results from the NETT randomized trial

BACKGROUND

In COPD patients, hyperinflation impairs cardiac function. We examined whether lung deflation improves oxygen pulse, a surrogate marker of stroke volume.

METHODS

In 129 NETT patients with cardiopulmonary exercise testing (CPET) and arterial blood gases (ABG substudy), hyperinflation was assessed with residual volume to total lung capacity ratio (RV/TLC), and cardiac function with oxygen pulse (O(2) pulse=VO(2)/HR) at baseline and 6 months. Medical and surgical patients were divided into "deflators" and "non-deflators" based on change in RV/TLC from baseline (∆RV/TLC). We defined deflation as the ∆RV/TLC experienced by 75% of surgical patients. We examined changes in O(2) pulse at peak and similar (iso-work) exercise. Findings were validated in 718 patients who underwent CPET without ABGs.

RESULTS

In the ABG substudy, surgical and medical deflators improved their RV/TLC and peak O(2) pulse (median ∆RV/TLC -18.0% vs. -9.3%, p=0.0003; median ∆O(2) pulse 13.6% vs. 1.8%, p=0.12). Surgical deflators also improved iso-work O(2) pulse (0.53 mL/beat, p=0.04 at 20 W). In the validation cohort, surgical deflators experienced a greater improvement in peak O(2) pulse than medical deflators (mean 18.9% vs. 1.1%). In surgical deflators improvements in O(2) pulse at rest and during unloaded pedaling (0.32 mL/beat, p<0.0001 and 0.47 mL/beat, p<0.0001, respectively) corresponded with significant reductions in HR and improvements in VO(2). On multivariate analysis, deflators were 88% more likely than non-deflators to have an improvement in O(2) pulse (OR 1.88, 95% CI 1.30-2.72, p=0.0008).

CONCLUSION

In COPD, decreased hyperinflation through lung volume reduction is associated with improved O(2) pulse.

Pulmonary hypertension in a stable community-based COPD population

STUDY OBJECTIVES

The etiology and prevalence of pulmonary hypertension (PH) in patients with stable chronic obstructive pulmonary disease (COPD) is uncertain. This study was done to determine the prevalence of PH in stable COPD outpatients and to evaluate the relationship between PH and indices of pulmonary function.

DESIGN

The study was a retrospective review of outpatients with COPD and PH defined as a history of cigarette smoking, pulmonary function tests (PFTs) that met GOLD criteria for airway obstruction, an echocardiogram within 6 months of PFTs, and a left ventricular ejection fraction (LVEF) >55%. Of the 159 individuals who met all inclusion criteria, 105 had a sufficient tricuspid regurgitant jet to measure systolic pulmonary artery pressure (sPAP). PH was defined as sPAP ≥36 mmHg.

MEASUREMENTS AND RESULTS

The prevalence of PH was 60% (63/105) in the study group. The mean sPAP in patients with PH was 45 ± 6 mmHg. COPD patients with PH were older (71.1 ± 11.8 vs. 63.7 ± 10.2 years, P = 0.001), had lower FEV(1)% predicted (51.8 ± 18.8 vs. 62.7 ± 20.5%, P = 0.006), a higher RV/TLC (0.55 ± 0.10 vs. 0.48 ± 0.11, P = 0.001), and a lower % predicted DL(CO) (59.6 ± 19.5% vs. 71.9 ± 24.9%, P = 0.006). Only age (P < 0.002) and prebronchodilator FEV(1)% predicted (P < 0.006) predicted PH by logistic regression analysis. No differences were observed in gender, BMI, smoking status, pack years, total lung capacity (TLC), or residual volume (RV).

CONCLUSION

PH is common in COPD. Older individuals and those with more airway obstruction are at greater risk for developing PH.

Lung transplantation and lung volume reduction surgery

Since the publication of the last edition of the Handbook of Physiology, lung transplantation has become widely available, via specialized centers, for a variety of end-stage lung diseases. Lung volume reduction surgery, a procedure for emphysema first conceptualized in the 1950s, electrified the pulmonary medicine community when it was rediscovered in the 1990s. In parallel with their technical and clinical refinement, extensive investigation has explored the unique physiology of these procedures. In the case of lung transplantation, relevant issues include the discrepant mechanical function of the donor lungs and recipient thorax, the effects of surgical denervation, acute and chronic rejection, respiratory, chest wall, and limb muscle function, and response to exercise. For lung volume reduction surgery, there have been new insights into the counterintuitive observation that lung function in severe emphysema can be improved by resecting the most diseased portions of the lungs. For both procedures, insights from physiology have fed back to clinicians to refine patient selection and to scientists to design clinical trials. This section will first provide an overview of the clinical aspects of these procedures, including patient selection, surgical techniques, complications, and outcomes. It then reviews the extensive data on lung and muscle function following transplantation and its complications. Finally, it reviews the insights from the last 15 years on the mechanisms whereby removal of lung from an emphysema patient can improve the function of the lung left behind.

Mechanisms of gas exchange response to lung volume reduction surgery in severe emphysema

Lung volume reduction surgery (LVRS) improves lung function, respiratory symptoms, and exercise tolerance in selected patients with chronic obstructive pulmonary disease, who have heterogeneous emphysema. However, the reported effects of LVRS on gas exchange are variable, even when lung function is improved. To clarify how LVRS affects gas exchange in chronic obstructive pulmonary disease, 23 patients were studied before LVRS, 14 of whom were again studied afterwards. We performed measurements of lung mechanics, pulmonary hemodynamics, and ventilation-perfusion (Va/Q) inequality using the multiple inert-gas elimination technique. LVRS improved arterial Po₂ (Pa(O₂)) by a mean of 6 Torr (P = 0.04), with no significant effect on arterial Pco₂ (Pa(CO₂)), but with great variability in both. Lung mechanical properties improved considerably more than did gas exchange. Post-LVRS Pa(O₂) depended mostly on its pre-LVRS value, whereas improvement in Pa(O(2)) was explained mostly by improved Va/Q inequality, with lesser contributions from both increased ventilation and higher mixed venous Po(2). However, no index of lung mechanical properties correlated with Pa(O₂). Conversely, post-LVRS Pa(CO₂) bore no relationship to its pre-LVRS value, whereas changes in Pa(CO₂) were tightly related (r² = 0.96) to variables, reflecting decrease in static lung hyperinflation (intrinsic positive end-expiratory pressure and residual volume/total lung capacity) and increase in airflow potential (tidal volume and maximal inspiratory pressure), but not to Va/Q distribution changes. Individual gas exchange responses to LVRS vary greatly, but can be explained by changes in combinations of determining variables that are different for oxygen and carbon dioxide.