Heart rate recovery after 6-min walk test predicts survival in patients with idiopathic pulmonary fibrosis

Meaningful Endpoints for Idiopathic Pulmonary Fibrosis (IPF) Clinical Trials: Emphasis on 'Feels, Functions, Survives'. Report of a Collaborative Discussion in a Symposium with Direct Engagement from Representatives of Patients, Investigators, the National Institutes of Health, a Patient Advocacy Organization, and a Regulatory Agency

Background: Idiopathic pulmonary fibrosis (IPF) carries significant mortality and unpredictable progression, with limited therapeutic options. Designing trials with patient-meaningful endpoints, enhancing the reliability and interpretability of results, and streamlining the regulatory approval process are of critical importance to advancing clinical care in IPF. Methods: A landmark in-person symposium in June 2023 assembled 43 participants from the US and internationally, including patients with IPF, investigators, and regulatory representatives, to discuss the immediate future of IPF clinical trial endpoints. Patient advocates were central to discussions, which evaluated endpoints according to regulatory standards and the FDA's 'feels, functions, survives' criteria. Results: Three themes emerged: 1) consensus on endpoints mirroring the lived experiences of patients with IPF; 2) consideration of replacing forced vital capacity (FVC) as the primary endpoint, potentially by composite endpoints that include 'feels, functions, survives' measures or FVC as components; 3) support for simplified, user-friendly patient-reported outcomes (PROs) as either components of primary composite endpoints or key secondary endpoints, supplemented by functional tests as secondary endpoints and novel biomarkers as supportive measures (FDA Guidance for Industry (Multiple Endpoints in Clinical Trials) available at: https://www.fda.gov/media/162416/download). Conclusions: This report, detailing the proceedings of this pivotal symposium, suggests a potential turning point in designing future IPF clinical trials more attuned to outcomes meaningful to patients, and documents the collective agreement across multidisciplinary stakeholders on the importance of anchoring IPF trial endpoints on real patient experiences-namely, how they feel, function, and survive. There is considerable optimism that clinical care in IPF will progress through trials focused on patient-centric insights, ultimately guiding transformative treatment strategies to enhance patients' quality of life and survival.

Impaired Dynamic Response of Oxygen Saturation During the 6-min Walk Test Is Associated With Mortality in Chronic Fibrosing Interstitial Pneumonia

BACKGROUND

The 6-min walk test (6MWT) is a common assessment of exercise-induced hypoxemia and exercise capacity used in patients with chronic fibrosing interstitial pneumonia (CFIP). However, whether the dynamic changes in SpO2 and heart rate during the 6MWT are associated with mortality in patients with CFIP has been undefined.

METHODS

This retrospective study enrolled 63 subjects with mild to severe CFIP who underwent the 6MWT. Subjects with CFIP were divided into 2 groups according to disease severity: mild, diffusing capacity of the lungs for carbon monoxide percentage predicted (%DLCO) > 55% and %FVC > 75%; and severe, %DLCO ≤ 55% and/or %FVC ≤ 75%. This study aimed to evaluate dynamic changes in the 6MWT including 6-min walk distance, change in SpO2 (ΔSpO2 ), SpO2 reduction time, SpO2 recovery time, change in heart rate (Δ heart rate), heart rate acceleration time, slope of heart rate acceleration, heart rate recovery at 1 min of rest after the 6MWT (HR-recovery), and dyspnea on exertion that are reflected by static pulmonary function and are related to exacerbation of CFIP and mortality.

RESULTS

Compared with subjects with mild CFIP, subjects with severe CFIP had significantly larger ΔSpO2 and longer SpO 2 reduction time and recovery time. The slope of heart rate, heart rate immediately after the 6MWT, and HR-recovery were lower in subjects with severe CFIP than in those with mild CFIP. In multiple regression analysis, percent vital capacity was significantly associated with SpO2 reduction time, and %DLCO was significantly associated with ΔSpO2 and SpO2 recovery time. Subjects with ΔSpO2 of > 10% and SpO2 recovery time of > 79 s had a significantly higher risk for exacerbation and mortality.

CONCLUSIONS

Dynamic changes in SpO2 and heart rate during the 6MWT were associated with risk for exacerbation and mortality in subjects with CFIP. Impaired dynamic response of SpO2 could reflect likelihood of exacerbation and increased mortality in CFIP.

Trajectories and Prognostic Significance of 6-Minute Walk Test Parameters in Fibrotic Interstitial Lung Disease: A Multicenter Study

BACKGROUND

Functional capacity, as measured by the 6-min walk test (6MWT), is often reduced in fibrotic interstitial lung disease (ILD). This study evaluated longitudinal changes and the prognostic significance of 6MWT parameters, and explored change in oxygenation status as a physiological criterion to define disease progression in patients with fibrotic ILD.

RESEARCH QUESTIONS

What are the trajectories and prognostic value of 6MWT parameters in patients with fibrotic ILD?

STUDY DESIGN AND METHODS

Using prospective registries in Australia and Canada, patients with idiopathic pulmonary fibrosis (IPF) and non-IPF fibrotic ILD were stratified by the presence of criteria for progressive pulmonary fibrosis (PPF). The cumulative incidence of exertional and resting hypoxemia and changes in 6-min walk distance (6MWD) and composite indices (distance-saturation product and distance-saturation-oxygen product) were determined, with prognostic significance evaluated at the time of meeting criteria for PPF. New-onset exertional or resting hypoxemia was evaluated as another potential criterion for PPF.

RESULTS

Patients with IPF/PPF (n = 126) and non-IPF/PPF (n = 227) had a similar cumulative incidence of exertional hypoxemia and annualized decline in 6MWD and composite indices, which varied across each PPF criterion. Patients with IPF/non-PPF (n = 231) and non-IPF/non-PPF (n = 531) had a significantly lower incidence of hypoxemia than those with IPF/PPF, with an annualized increase in 6MWD and composite indices in the non-IPF/non-PPF group. Exertional or resting hypoxemia at the time of meeting criteria for PPF was independently associated with reduced transplant-free survival in IPF and non-IPF, adjusting for patient demographics and lung function. Adding new-onset exertional or resting hypoxemia as a physiological criterion reduced the median time to development of PPF from 11.2 to 6.7 months in IPF and from 11.7 to 5.6 months in non-IPF in patients who eventually met both definitions (P < .001 for both).

INTERPRETATION

Patients with IPF/PPF and non-IPF/PPF have comparable deterioration in functional capacity. Oxygenation status provides prognostic information in PPF and may assist in defining disease progression in fibrotic ILD.

Pulmonary hypertension in interstitial lung disease: Clinical trial design and endpoints: A consensus statement from the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative-Group 3 Pulmonary Hypertension

Pulmonary hypertension (PH) associated with interstitial lung disease (ILD) is an attractive target for clinical trials of PH medications. There are many factors that need to be considered to prime such studies for success. The patient phenotype most likely to respond to the intervention requires weighing the extent of the parenchymal lung disease against the severity of the hemodynamic impairment. The inclusion criteria should not be too restrictive, thus enabling recruitment. The trial should be of sufficient duration to meet the chosen endpoint which should reflect how the patient feels, functions, or survives. This paper summarizes prior studies in PH-ILD and provides a framework of the type of studies to be considered. Inclusion criteria, clinical trial endpoints, and pharmacovigilance in the context of PH-ILD trials are also addressed. Through lessons learnt from prior studies, suggestions and guidance for future clinical trials in PH-ILD are also provided.

Predicting 6-minute walking test outcomes in patients with chronic obstructive pulmonary disease without physical performance measures

BACKGROUND AND OBJECTIVE

Chronic obstructive pulmonary disease (COPD) requires a multifactorial assessment, evaluating the airflow limitation and symptoms of the patients. The 6-min walk test (6MWT) is commonly used to evaluate the functional exercise capacity in these patients. This study aims to propose a novel predictive model of the major 6MWT outcomes for COPD assessment, without physical performance measurements.

METHODS

Cardiopulmonary and clinical parameters were obtained from fifty COPD patients. These parameters were used as inputs of a Bayesian network (BN), which integrated three multivariate models including the 6-min walking distance (6MWD), the maximum HR (HR_max) after the walking, and the HR decay 3 min after (HRR₃). The use of BN allows the assessment of the patients' status by predicting the 6MWT outcomes, but also inferring disease severity parameters based on actual patient's 6MWT outcomes.

RESULTS

Firstly, the correlation obtained between the estimated and actual 6MWT measures was strong (R = 0.84, MAPE = 8.10% for HR_max) and moderate (R = 0.58, MAPE = 15.43% for 6MWD and R = 0.58, MAPE = 32.49% for HRR₃), improving the classical methods to estimate 6MWD. Secondly, the classification of disease severity showed an accuracy of 78.3% using three severity groups, which increased up to 84.4% for two defined severity groups.

CONCLUSIONS

We propose a powerful two-way assessment tool for COPD patients, capable of predicting 6MWT outcomes without the need for an actual walking exercise. This model-based tool opens the way to implement a continuous monitoring system for COPD patients at home and to provide more personalized care.

The 6-min walk test as a primary end-point in interstitial lung disease

There is a need for clinical trial end-points to better assess how patients feel and function, so that interventions can be developed which alleviate symptoms and improve quality of life. Use of 6-min walk test (6MWT) outcomes as a primary end-point in interstitial lung disease (ILD) trials is growing, particularly for drugs targeting concurrent pulmonary hypertension. However, 6MWT outcomes may be influenced differentially by interstitial lung and pulmonary vascular components of ILD, making interpretation complicated. We propose that using 6MWT outcomes, including 6-min walk distance or oxygen desaturation, as primary end-points should depend upon the study population (how advanced the ILD is; whether vasculopathy is significant), the degree of disease progression, and, importantly, the effect of study treatment expected. We argue that the 6MWT as a single outcome measure is suitable as a primary end-point if the treatment goal is to improve functional performance or prevent disease progression within a study population of patients with advanced ILD or those with ILD and co-existent vasculopathy. In addition, we discuss the potential of composite primary end-points incorporating 6MWT outcomes, outlining important considerations to ensure that they are appropriate for the study population and treatment goals.

Effect of pulmonary rehabilitation on heart rate recovery in adult individuals with asthma or chronic obstructive pulmonary disease

Introduction: Heart rate recovery (HRR) after exercise is a marker of disease severity and prognosis in cardiovascular and respiratory disorders. More than 30% of adult individuals with asthma may show a slow HRR. Pulmonary rehabilitation improves exercise capacity in individuals with asthma or chronic obstructive pulmonary disease (COPD).

Aim: The study aimed to evaluate the effect of pulmonary rehabilitation on HRR in individuals with asthma as compared to those with COPD.

Methods: Retrospective analysis of HRR one minute after the six-minute walking test (6MWT) was performed before and after an exercise training program. The COPD Assessment Test (CAT), Barthel Index-Dyspnea (BI-D), Medical Research Council (MRC) score for dyspnea, and the Five-Times-Sit-to-Stand test (5STS) were also assessed as secondary outcome measures.

Results: Slow HRR prevalence was significantly lower in individuals with asthma than with COPD (29.1 vs. 46.7%, respectively: p = 0.003). Post-program HRR did not change in more than 70% of individuals in either population and improved in 16% of both populations, whereas it actually worsened in 12 and 10% of individuals with asthma and COPD, respectively. The outcome measures significantly improved in both populations, irrespective of baseline HRR.

Conclusion: In individuals with asthma or COPD, exercise training does not significantly improve HRR.

Heart rate recovery in adult individuals with asthma

Slow heart rate recovery (HRR) after exercise is a predictor of overall mortality in individuals with and without cardiovascular or respiratory disorders. No data on adults with asthma are available. The purpose of the study is to evaluate the prevalence of slow HRR in these individuals as compared with those with chronic obstructive pulmonary disease (COPD). We performed a retrospective analysis of baseline characteristics and physiological response to the six-minute walking distance test of stable individuals with asthma or COPD. Slow HRR was defined as HRpeak - HR at 1 minute after end exercise <12 bpm. Individuals with asthma walked significantly longer (median (IQR): 455 (385-512) vs 427 (345-485) meters; p=0.005) with a lower prevalence of slow HRR (30.3% vs 49.0%, respectively: p<0.001) than those with COPD. Individuals with asthma and slow HRR were older and walked less than those with normal HRR, without any difference in airway obstruction or in disease severity. Multivariate analysis showed that only the difference HRpeak - baseline HR (∆HR), was a predictor of slow HRR in both groups. More than 30% of adult individuals with asthma may show slow HRR. Only exercise ∆HR but no baseline characteristic seems to predict the occurrence of slow HRR.

Home monitoring of physiology and symptoms to detect interstitial lung disease exacerbations and progression: a systematic review

Background

Acute exacerbations (AEs) and disease progression in interstitial lung disease (ILD) pose important challenges to clinicians and patients. AEs of ILD are variable in presentation but may result in rapid progression of ILD, respiratory failure and death. However, in many cases AEs of ILD may go unrecognised so that their true impact and response to therapy is unknown. The potential for home monitoring to facilitate early, and accurate, identification of AE and/or ILD progression has gained interest. With increasing evidence available, there is a need for a systematic review on home monitoring of patients with ILD to summarise the existing data. The aim of this review was to systematically evaluate the evidence for use of home monitoring for early detection of exacerbations and/or progression of ILD.

Method

We searched Ovid-EMBASE, MEDLINE and CINAHL using Medical Subject Headings (MeSH) terms in accordance with the PRISMA guidelines (PROSPERO registration number CRD42020215166).

Results

13 studies involving 968 patients have demonstrated that home monitoring is feasible and of potential benefit in patients with ILD. Nine studies reported that mean adherence to home monitoring was >75%, and where spirometry was performed there was a significant correlation (r=0.72–0.98, p<0.001) between home and hospital-based readings. Two studies suggested that home monitoring of forced vital capacity might facilitate detection of progression in idiopathic pulmonary fibrosis.

Conclusion

Despite the fact that individual studies in this systematic review provide supportive evidence suggesting the feasibility and utility of home monitoring in ILD, further studies are necessary to quantify the potential of home monitoring to detect disease progression and/or AEs.

First systematic review that provides supportive evidence for the feasibility and utility of home monitoring in ILD; further studies are necessary to evaluate approaches to detect exacerbation and/or progressionhttps://bit.ly/2Y8OCJL

Evidence for impaired chronotropic responses to and recovery from 6-minute walk test in women with post-acute COVID-19 syndrome

NEW FINDINGS

What is the central question of this study? Are chronotropic responses to a 6-minute walk test different in women with post-acute coronavirus disease 2019 (COVID-19) syndrome compared with control subjects? What is the main finding and its importance? Compared with control subjects, the increase in heart rate was attenuated and recovery delayed after a 6-minute walk test in participants after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Women reporting specific symptoms at time of testing had greater impairments compared with control subjects and SARS-CoV-2 participants not actively experiencing these symptoms. Such alterations have potential to constrain not only exercise tolerance but also participation in free-living physical activity in women during post-acute recovery from COVID-19.

ABSTRACT

The short-term cardiopulmonary manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are well defined. However, the implications of cardiopulmonary sequelae, persisting beyond acute illness, on physical function are largely unknown. Herein, we characterized heart rate responses to and recovery from a 6-minute walk test (6MWT) in women ∼3 months after mild-to-moderate SARS-CoV-2 infection compared with non-infected control subjects. Forty-five women (n = 29 SARS-CoV-2; n = 16 controls; age = 56 ± 11 years; body mass index = 25.8 ± 6.0 kg/m² ) completed pulmonary function testing and a 6MWT. The SARS-CoV-2 participants demonstrated reduced total lung capacity (84 ± 8 vs. 93 ± 13%; P = 0.006), vital capacity (87 ± 10 vs. 93 ± 10%; P = 0.040), functional residual capacity (75 ± 16 vs. 88 ± 16%; P = 0.006) and residual volume (76 ± 18 vs. 93 ± 22%; P = 0.001) compared with control subjects. No between-group differences were observed in 6MWT distance (P = 0.194); however, the increase in heart rate with exertion was attenuated among SARS-CoV-2 participants compared with control subjects (+52 ± 20 vs. +65 ± 18 beats/min; P = 0.029). The decrease in heart rate was also delayed for minutes 1-5 of recovery among SARS-CoV-2 participants (all P < 0.05). Women reporting specific symptoms at the time of testing had greater impairments compared with control subjects and SARS-CoV-2 participants not actively experiencing these symptoms. Our findings provide evidence for marked differences in chronotropic responses to and recovery from a 6MWT in women several months after acute SARS-CoV-2 infection.

Identifying a Heart Rate Recovery Criterion After a 6-Minute Walk Test in COPD

BACKGROUND

Slow heart rate recovery (HRR) after exercise is associated with autonomic dysfunction and increased mortality. What HRR criterion at 1-minute after a 6-minute walk test (6MWT) best defines pulmonary impairment?.

STUDY DESIGN AND METHODS

A total of 5008 phase 2 COPDGene (NCT00608764) participants with smoking history were included. A total of 2127 had COPD and, of these, 385 were followed-up 5-years later. Lung surgery, transplant, bronchiectasis, atrial fibrillation, heart failure and pacemakers were exclusionary. HR was measured from pulse oximetry at end-walk and after 1-min seated recovery. A receiver operator characteristic (ROC) identified optimal HRR cut-off. Generalized linear regression determined HRR association with spirometry, chest CT, symptoms and exacerbations.

RESULTS

HRR after 6MWT (bt/min) was categorized in quintiles: ≤5 (23.0% of participants), 6-10 (20.7%), 11-15 (18.9%), 16-22 (18.5%) and ≥23 (18.9%). Compared to HRR≤5, HRR≥11 was associated with (p<0.001): lower pre-walk HR and 1-min post HR; greater end-walk HR; greater 6MWD; greater FEV1%pred; lower airway wall area and wall thickness. HRR was positively associated with FEV1%pred and negatively associated with airway wall thickness. An optimal HRR ≤10 bt/min yielded an area under the ROC curve of 0.62 (95% CI 0.58-0.66) for identifying FEV1<30%pred. HRR≥11 bt/min was the lowest HRR associated with consistently less impairment in 6MWT, spirometry and CT variables. In COPD, HRR≤10 bt/min was associated with (p<0.001): ≥2 exacerbations in the previous year (OR=1.76[1.33-2.34]); CAT≥10 (OR=1.42[1.18-1.71]); mMRC≥2 (OR=1.42[1.19-1.69]); GOLD 4 (OR=1.98[1.44-2.73]) and GOLD D (OR=1.51[1.18-1.95]). HRR≤10 bt/min was predicted COPD exacerbations at 5-year follow-up (RR=1.83[1.07-3.12], P=0.027).

CONCLUSION

HRR≤10 bt/min after 6MWT in COPD is associated with more severe expiratory flow limitation, airway wall thickening, worse dyspnoea and quality of life, and future exacerbations, suggesting that an abnormal HRR≤10 bt/min after a 6MWT may be used in a comprehensive assessment in COPD for risk of severity, symptoms and future exacerbations.

Effects of oxygen supplementation in autonomic nervous system function during exercise in patients with idiopathic pulmonary fibrosis and exertional desaturation

INTRODUCTION

Patients with idiopathic pulmonary fibrosis (IPF) have reduced exercise capacity and often present exertional dyspnea and desaturation. The role of autonomic nervous system (ANS) as a pathogenetic contributor to this dysfunction has not been evaluated.

OBJECTIVE

To evaluate whether improvement of arterial oxygen saturation (SpO₂ ) via oxygen supplementation results to ANS function improvement, during steady state submaximal exercise.

METHODS

This is a secondary analysis of a single-blind, randomized, placebo-controlled, cross-over trial, including 12 IPF patients, with isolated exertional desaturation. Following a maximal cardiopulmonary test, participants underwent two submaximal steady state tests during which they received either supplementary oxygen or medical air. Continuous beat-to-beat blood pressure measurements were recorded (Finapres Medical Systems, Amsterdam, The Netherlands). Autonomic function was assessed non-invasively by heart rate variability (HRV); root mean square of successive differences (RMSSD) and standard-deviation-Poincare-plot (SD1) were used as indices of parasympathetic output. Entropy and detrended fluctuation analysis (DFA) were also used.

RESULTS

During rest, oxygen supplementation did not significantly alter RMSSD and SD1. During exercise, subjects presented no significant alterations compared with baseline, in most HRV indices examined. There was no improvement of this behavior with O₂ -supplementation. Approximate-entropy increased during exercise, with no differences between protocols.

CONCLUSIONS

IPF patients presented an inadequate adaptive response of their ANS to exercise and recovery. Although oxygen supplementation significantly prolonged exercise duration and prevented the substantial exertional desaturation, the blunted vagal response to steady-state exercise in these patients was not improved, suggesting that acute oxygen supplementation does not sufficiently improve ANS dysfunction in these patients.

Clinical evaluation on idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic fatal pulmonary disease characterized by complex illness condition. There is no effective treatment at present except lung transplantation. The comprehensive evaluation is helpful for the management of patients with IPF in hierarchical stages. Therefore, it is very important to evaluate IPF by various independent factors. At present, the commonly used methods for clinical evaluation on IPF include assessment of health-related quality of life, assessment of physiological function, assessment of imaging, assessment of laboratory examination, and multi-dimensional assessment system. However, there are different advantages and disadvantages on diverse evaluation methods for the evaluation of IPF.

IC4: a new combined predictive index of mortality in idiopathic pulmonary fibrosis

BACKGROUND

While a number of individual patient characteristics are associated with survival in idiopathic pulmonary fibrosis (IPF), their incorporation into combined indexes, such as the GAP index, has been shown to increase the predictive capacity. It is unknown whether the predictive capacity of GAP-derived indexes that also include anthropometric and exercise parameters is superior to the original instrument.

METHODS

We tested the four-year survival predictive capacity of a modified, adimensional and multiplicative GAP index (IC4) that included percent forced vital capacity (FVC%), diffusing capacity of the lung for carbon monoxide (DLCO%), body mass index (BMI), and six-minute walk distance (6MWD) in 90 IPF patients recruited from two centres in France and Italy.

RESULTS

In ROC comparisons, the AUC of the IC4 (0.859, 95% CI 0.770-0.924 p<0.0001) was significantly higher than the AUCs of the individual components, their two-three component combinations, and the original GAP index, with 77% sensitivity and 89% specificity. Mean survival was 14.0±11.7, 23.2±12.7, 34.9±14.8, and 40.8±12.9 months, and survival rate was 0%, 14%, 39% and 73%, in IC4 quartile 1, 2, 3, and 4, respectively.

CONCLUSIONS

The IC4, a combined adimensional index incorporating FVC%, DLCO%, BMI and 6MWD, provides superior capacity to predict mortality, when compared to its individual components, their other combinations, and the GAP index, in patients with IPF.

Clinical relevance of endpoints in clinical trials for acid sphingomyelinase deficiency enzyme replacement therapy

BACKGROUND

Acid sphingomyelinase deficiency (ASMD) also known as Niemann-Pick disease, is a rare lysosomal storage disorder with a diverse disease spectrum that includes slowly progressive, chronic visceral (type B) and neurovisceral forms (intermediate type A/B), in addition to infantile, rapidly progressive fatal neurovisceral disease (type A).

PURPOSE AND METHODS

We review the published evidence on the relevance of splenomegaly and reduced lung diffusion capacity to the clinical burden of chronic forms of ASMD. Targeted literature searches were conducted to identify relevant ASMD and non-ASMD studies for associations between diffusing capacity of the lungs for carbon monoxide (DL_CO) and splenomegaly, with clinical parameters and outcome measures.

RESULTS

Respiratory disease and organomegaly are primary and independent contributors to mortality, disease burden, and morbidity for patients with chronic ASMD. The degree of splenomegaly correlates with short stature, atherogenic lipid profile, and degree of abnormality of hematologic parameters, and thus may be considered a surrogate marker for bleeding risk, abnormal lipid profiles and possibly, liver fibrosis. Progressive lung disease is a prevalent clinical feature of chronic ASMD, contributing to a decreased quality of life (QoL) and an increased disease burden. In addition, respiratory-related complications are a major cause of mortality in ASMD.

CONCLUSIONS

The reviewed evidence from ASMD natural history and observational studies supports the use of lung function and spleen volume as clinically meaningful endpoints in ASMD trials that translate into important measures of disease burden for patients.

Pulmonary Rehabilitation Effects on Heart Rate Recovery in Restrictive Lung Disease Patients

Objective:

The study aimed to evaluate heart rate recovery in subjects with restrictive lung disease (RLD) and healthy age matched subjects before and after a rehabilitation program (RP).

Methods:

This is a cross-sectional study on subjects of both genders, with over 40 years old with and without any diagnosis of restrictive lung disease and who were able to perform physical tasks were included in the study. They were evaluated for sociodemographic profile, lifestyle (ILP), Framingham score, physical capacity (6MWT and treadmill incremental testing) and heart rate recovery before and after RP.

Results:

65 subjects were assigned into either G1 (patients with RLD, n=26) or G2 (healthy subjects, n= 39). Initially, patients with RLD increased their heart rate (HR) from 79 to 120bpm, and after the recovery post-exercise, the first minute they reduced HR by nine beats. In the fifth minute after the exercise, HR returned to baseline values. After the RP, mean HR was 71bpm and 79bpm in G1 and G2, respectively. Increased mean 6MWT peak HR in both the groups was seen (110bpm and 120bpm, G1 and G2, respectively). In the first minute of resting, mean HR decreased to 86bpm (- 24bpm) and 72 (-48bpm) in G1 and G2, respectively. In the fifth minute after exercise, HR recovery in both the groups was complete.

Conclusion:

The RP was effective in improving the first-minute heart rate recovery in patients with restrictive lung disease and, there was an inverse correlation of heart rate recovery with disease severity.

Six-Minute Walk Test: Clinical Role, Technique, Coding, and Reimbursement

The 6-min walk test (6MWT) is a commonly used test for the objective assessment of functional exercise capacity for the management of patients with moderate-to-severe pulmonary disease. Unlike pulmonary function testing, the 6MWT captures the often coexisting extrapulmonary manifestations of chronic respiratory disease, including cardiovascular disease, frailty, sarcopenia, and cancer. In contrast with cardiopulmonary exercise stress testing, this test does not require complex equipment or technical expertise. In this low complexity, safe test, the patient is asked to walk as far as possible along a 30-m minimally trafficked corridor for a period of 6 min with the primary outcome measure being the 6-min walk distance (6MWD) measured in meters. There has been interest in other derived indexes, such as distance-desaturation product (the product of nadir oxygen saturation and walk distance), which in small studies has been predictive of morbidity and mortality in certain chronic respiratory conditions. Special attention to methodology is required to produce reliable and reproducible results. Factors that can affect walk distance include track layout (continuous vs straight), track length, oxygen amount and portability, learning effect, and verbal encouragement. The absolute 6MWD and change in 6MWD are predictive of morbidity and mortality in patients with COPD, pulmonary arterial hypertension, and idiopathic pulmonary fibrosis and patients awaiting lung transplant, highlighting its use in management decisions and clinical trials. As of January 2018, Current Procedural Terminology code 94620 (simple pulmonary stress test) has been deleted and replaced by two new codes, 94617 and 94618. Code 94617 includes exercise test for bronchospasm including pre- and postspirometry, ECG recordings, and pulse oximetry. Code 94618, pulmonary stress testing (eg, 6MWT), includes the measurement of heart rate, oximetry, and oxygen titration when performed. If 94620 is billed after January 2018 it will not be reimbursed.

Using SpO2 Recovery Index after a 6-Minute Walk Test to Predict Respiratory-Related Events in Hospitalized Patients with Interstitial Pneumonia

Although the prognostic factors of interstitial pneumonia (IP) patients have been reported, IP has poor prognosis. Hospitalized patients with IP have severely impaired pulmonary diffusion capacity and prominent desaturation. We hypothesized that determining oxygen saturation recovery (SpO₂ recovery index) after the 6-minute walk test (6MWT) can provide additional prognostic information regarding rehospitalization for respiratory-related events. We evaluated 73 IP patients at our hospital for demographic characteristics, pulmonary function tests and 6MWT. The Kaplan–Meier method was used to estimate rehospitalisation for respiratory-related events using SpO₂ recovery index. Cox regression analysis revealed a relationship between SpO₂ recovery index and rehospitalisation. The optimum cutoff value of SpO₂ recovery index was 4% (sensitivity, 71.4%; specificity, 79.2%). SpO₂ recovery index was most closely related to pulmonary diffusion capacity (r = 0.684, P < 0.001). In a multivariable model, it was the strongest independent predictor of rehospitalisation for respiratory-related events (hazard ratio, 0.3; 95% confidence interval, 0.10–0.90; P = 0.032). In this study, we estimated pulmonary diffusion capacity using SpO₂ recovery index values obtained from 6MWT. A SpO₂ recovery index of <4% can be useful in predicting rehospitalisation for respiratory-related events.

Pulmonary hypertension and chronic lung disease: where are we headed?

Pulmonary hypertension related to chronic lung disease, mainly represented by COPD and idiopathic pulmonary fibrosis, is associated with a worse outcome when compared with patients only affected by parenchymal lung disease. At present, no therapies are available to reverse or slow down the pathological process of this condition and most of the clinical trials conducted to date have had no clinically significant impact. Nevertheless, the importance of chronic lung diseases is always more widely recognised and, along with its increasing incidence, associated pulmonary hypertension is also expected to be growing in frequency and as a health burden worldwide. Therefore, it is desirable to develop useful and reliable tools to obtain an early diagnosis and to monitor and follow-up this condition, while new insights in the therapeutic approach are explored.

Comparing effectiveness of prognostic tests in idiopathic pulmonary fibrosis

Introduction: Idiopathic pulmonary fibrosis (IPF) is a debilitating and progressive fibrotic interstitial lung disease often resulting in death over several years. Prediction of disease course or survival remains of keen interest for clinicians and patients though a commonly used test or tool remain elusive. Areas covered: We undertook a comprehensive review of the published literature highlighting prognostic indicators and predictors of survival in IPF. Baseline and longitudinal clinical, functional, histopathologic, and radiologic findings have been extensively studied as prognostic predictors, both individually and in composite models. Recent approaches include automated quantifiable radiologic scoring, circulating biomarkers, and genetic polymorphisms or abnormalities. This review highlights individual and composite predictors and their relative utility in clinical practice and research studies. Expert opinion: There is a growing body of knowledge highlighting readily available individual and composite predictors of outcome, though none have come to the forefront for common clinical use. Recent advances include quantitative imaging analysis, circulating serologic markers, and genetic testing, which may be more standardized and less prone to lead-time bias or related complications and comorbidities.

Utility of the six-minute walk test in patients with idiopathic pulmonary fibrosis

The six-minute walk test (6MWT) is a simple test that is widely used to assess functional exercise capacity in patients with idiopathic pulmonary fibrosis (IPF). Patients with IPF have reduced exercise capacity due to a number of factors, such as impaired respiratory mechanics and circulatory problems. As a self-paced and usually submaximal exercise test, the 6MWT reflects the exercise level of everyday activities. Variables measured during the 6MWT, such as six-minute walk distance (6MWD) and desaturation, are strong predictors of mortality in patients with IPF. However, the results of a 6MWT are affected by numerous factors, including age, body size, comorbidities and the use of supplemental oxygen during the test, and these need to be borne in mind when interpreting the results of individual and serial tests. Clinical studies, including trials of potential therapies for IPF, have differed in the methodology used to implement the 6MWT, hindering the comparison of results across studies. In this review, I describe the utility of the 6MWT in patients with IPF and provide recommendations for standardisation of the test for use both in clinical practice and research. A brief video on how to set up and administer the 6MWT is available at http://www.usscicomms.com/respiratory/lancaster/6mwt/

Evaluating disease severity in idiopathic pulmonary fibrosis

Accurate assessment of idiopathic pulmonary fibrosis (IPF) disease severity is integral to the care provided to patients with IPF. However, to date, there are no generally accepted or validated staging systems. There is an abundance of data on using information acquired from physiological, radiological and pathological parameters, in isolation or in combination, to assess disease severity in IPF. Recently, there has been interest in using serum biomarkers and computed tomography-derived quantitative lung fibrosis measures to stage disease severity in IPF. This review will focus on the suggested methods for staging IPF, at baseline and on serial assessment, their strengths and limitations, as well as future developments.

[Sub-maximal aerobic capacity and quality of life of patients with rheumatoid arthritis]

BACKGROUND

Studies about sub-maximal aerobic capacity of patients with rheumatoid arthritis are scarce.

AIMS

To assess the sub-maximal aerobic capacity of these patients through the 6-min walk test, estimated age of the "muscular and cardiorespiratory" chain.

METHODS

Thirty-seven consecutive patients (aged 20 to 60 years) with newly diagnosed rheumatoid arthritis will be included. Non-inclusion criteria will be: use of drugs (e.g.; methotrexate, beta-blockers), orthopaedic or rheumatologic conditions (other than rheumatoid arthritis) that may alter walking ability and recent infections. Exclusion criteria will be: 6-min walking test contra-indications and imperfect performance of the required lung function and walking maneuvers. Signs of walking intolerance will be: test interruption, distance ≤lower limit of normal, dyspnea score ≥5/10 (visual analogue scale) at the end of the test, haemoglobin oxygen saturation (SpO₂) drop ≥5%, cardiac frequency at the end of the test ≤60% of maximum predicted. An estimated "muscular and cardiorespiratory chain" age higher than the chronological one will be considered as a sign of accelerated ageing.

EXPECTED RESULTS

A high percentage of patients suffering from rheumatoid arthritis would show evidences of walking limitation and accelerated "muscular and cardiorespiratory chain" ageing. There would be a significant correlation between the walking test and clinical, biological, radiological and pulmonary function data and the patients' quality-of-life status.

Non-invasive screening for pulmonary hypertension in idiopathic pulmonary fibrosis

BACKGROUND

Pulmonary hypertension (PH) is a common complication of idiopathic pulmonary fibrosis (IPF) that is associated with poor prognosis. Noninvasive screening for PH in IPF patients is challenging and a combination of several noninvasive determinations can improve discrimination.

METHODS

We included 235 IPF patients who underwent right heart catheterization (RHC) as part of the lung transplant evaluation. We measured electrocardiographic (ECG) and echocardiographic variables as well as the pulmonary artery (PA) and ascending aorta (AA) diameters on chest CT. We recorded results of arterial blood gases (ABG), pulmonary function (PFT) and 6-min walk tests (6MWT).

RESULTS

Several variables were predictors of PH in IPF patients in univariable models including a lower arterial oxygenation and 6MWT distance; worse right ventricular (RV) function, rightward deviation of the QRS axis and a higher FVC/DLCOc ratio, PA/AA diameter ratio, and estimated RV systolic pressure. In multivariable analysis, a worse RV function and higher PA/AA ratio remained predictors of PH (c-index 0.75 (0.65-0.84)). Similarly, a worse RV function, a higher PA/AA ratio and a rightward QRS axis deviation were independent predictors of precapillary PH (c-index 0.86 (0.76-0.92)). A combination of PA/AA diameter ratio <1.1, a QRS axis <90° and normal RV function showed a negative predictive value of 85% for precapillary PH.

CONCLUSIONS

There are significant differences in ECG, echocardiographic, chest CT, PFT and ABG parameters between IPF patients with and without PH. However, these noninvasive tests alone or combination have limited discrimination ability for PH screening in IPF.

IPF clinical trial design and endpoints

Purpose of review

There remains a dire need for therapies that impact the clinical course of patients with idiopathic pulmonary fibrosis (IPF). Indeed, there is a surge of interest in IPF therapeutics, with many candidate agents in various stages of development. Optimal design and implementation of the appropriate prospective clinical trials are essential to demonstrate clinical efficacy of promising drugs for the treatment of IPF. A key element in the success of such clinical trials is the choice of the best endpoint(s) to match the design of the study.

Recent findings

Although the results of many IPF clinical trials have been disappointing, these trials have provided valuable insights into the epidemiology and natural history of the disease and have sparked debate into the best clinical trial designs and endpoints.

Summary

This review will discuss the various clinical trial endpoints that have been used or proposed with a focus on their potential utility, as well as possible pitfalls that investigators should consider in the design of such studies.

Video abstract

http://links.lww.com/COPM/A13

Lung transplantation in IIP: A review

The idiopathic interstitial pneumonias (IIP) encompass a large and diverse subtype of interstitial lung disease (ILD) with idiopathic pulmonary fibrosis (IPF) and non-specific interstitial pneumonia (NSIP) being the most common types. Although pharmacologic treatments are available for most types of IIP, many patients progress to advanced lung disease and require lung transplantation. Close monitoring with serial functional and radiographic tests for disease progression coupled with early referral for lung transplantation are of great importance in the management of patients with IIP. Both single and bilateral lung transplantation are acceptable procedures for IIP. Procedure selection is a complex decision influenced by multiple factors related to patient, donor and transplant centre. While single lung transplant may reduce waitlist time and mortality, the long-term outcomes after bilateral lung transplantation may be slightly superior. There are numerous complications following lung transplantation including primary graft dysfunction, chronic lung allograft dysfunction (CLAD), infections, gastroesophageal reflux disease (GERD) and airway disease that limit post-transplant longevity. The median survival after lung transplantation is 4.7 years in patients with ILD, which is less than in patients with other underlying lung diseases. Although long-term survival is limited, this intervention still conveys a survival benefit and improved quality of life in suitable IIP patients with advanced lung disease and chronic hypoxemic respiratory failure.

Comorbidities in idiopathic pulmonary fibrosis patients: a systematic literature review

Idiopathic pulmonary fibrosis (IPF) is associated with a fatal prognosis and manifests in patients over 60 years old who may have comorbidities. The prevalence and impact of comorbidities on the clinical course of IPF is unclear.

This systematic literature review examined the prevalence of comorbidities and mortality associated with comorbidities in IPF patients. Relevant observational studies published in English from January 1990 to January 2015 identifiedviaMEDLINE and EMBASE were included; bibliographies of articles were also searched.

Among the 126 studies included, prevalence of pulmonary hypertension (PH) was 3–86%, 6–91% for obstructive sleep apnoea, 3–48% for lung cancer and 6–67% for chronic obstructive pulmonary disease (COPD). Nonrespiratory comorbidities included ischaemic heart disease (IHD) (3–68%) and gastro-oesophageal reflux (GER) (0–94%). Mortality was highest among patients with IPF and lung cancer. Most studies assessed relatively small samples of patients with IPF.

PH, COPD, lung cancer, GER and IHD are significant comorbidities; differences in IPF severity, case definitions and patient characteristics limited the comparability of findings. The identification and prompt treatment of comorbidities may have a clinically significant impact on overall outcome that is meaningful for patients with IPF.

Heart Rate Recovery as a Preoperative Test of Perioperative Complication Risk

The autonomic nervous system plays important physiologic roles in a variety of organ systems. Autonomic dysfunction has been shown to be predictive of increased mortality in patients with cardiovascular disease. Its importance in patients with chronic respiratory disorders has been described in recent years. Here, we summarize the prognostic value of autonomic dysfunction, as reflected by impaired heart rate recovery (HRR), in patients with chronic respiratory disorders, including chronic obstructive pulmonary disease, interstitial lung disease, and lung cancer. We suggest that HRR may be clinically useful in the preoperative physiologic evaluation, specifically in lung cancer patients being considered for surgery.

Heart rate recovery is an important predictor of outcomes in patients with connective tissue disease-associated pulmonary hypertension

Reduced heart rate recovery (HRR) after exercise is associated with increased mortality in cardiac and pulmonary diseases. We sought to evaluate the association between HRR after the 6-minute walk test (6MWT) and outcomes in patients with connective tissue disease-associated pulmonary hypertension (CTD-PH). Data were obtained by review of the medical records. HRR was defined as the difference in heart rate at the end of the 6MWT and after 1 minute (HRR1), 2 minutes (HRR2), and 3 minutes (HRR3) of rest. All patients with pulmonary hypertension and a diagnosis of systemic sclerosis, systemic lupus erythematosus, or mixed connective tissue disease who underwent the 6MWT between August 1, 2009, and October 30, 2011, were included (n = 66). By Kaplan-Meier analysis, HRR1, HRR2, and HRR3 at different cutoff points were all good predictors, with HRR1 of <16 being the best predictor of time to clinical worsening (log-rank P < 0.0001), hospitalization (log-rank P = 0.0001), and survival (log-rank P < 0.003). By proportional hazards regression, patients with HRR1 of <16 were at increased risk of clinical worsening (hazard ratio [HR]: 6.4 [95% confidence interval (CI): 2.6-19.2]; P < 0.0001], hospitalization (HR: 6.6 [95% CI: 2.4-23]; P < 0.0001), and death (HR: 4.5 [95% CI: 1.6-15.7]; P = 0.003). Patients in the highest tercile (HRR1 of ≥19) were unlikely to have a clinical worsening event (HR: 0.1 [95% CI: 0.04-0.5]; P = 0.001], to be hospitalized (HR: 0.1 [95% CI: 0.02-0.5]; P = 0.001), or to die (HR: 0.3 [95% CI: 0.07-0.9]; P = 0.04]. In conclusion, in patients with CTD-PH, abnormal HRR1 (defined as HRR1 of <16) after the 6MWT is a strong predictor of clinical worsening, time to clinical worsening, survival, and hospitalization.

Managing comorbidities in idiopathic pulmonary fibrosis

Major risk factors for idiopathic pulmonary fibrosis (IPF) include older age and a history of smoking, which predispose to several pulmonary and extra-pulmonary diseases. IPF can be associated with additional comorbidities through other mechanisms as either a cause or a consequence of these diseases. We review the literature regarding the management of common pulmonary and extra-pulmonary comorbidities, including chronic obstructive pulmonary disease, lung cancer, pulmonary hypertension, venous thromboembolism, sleep-disordered breathing, gastroesophageal reflux disease, coronary artery disease, depression and anxiety, and deconditioning. Recent studies have provided some guidance on the management of these diseases in IPF; however, most treatment recommendations are extrapolated from studies of non-IPF patients. Additional studies are required to more accurately determine the clinical features of these comorbidities in patients with IPF and to evaluate conventional treatments and management strategies that are beneficial in non-IPF populations.

Impaired functional capacity predicts mortality in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with increased mortality, for which impaired functional capacity (IFC) has been established as a surrogate. We sought to assess whether IFC is associated with increased mortality in patients with OSA and whether IFC is predictive of increased mortality after accounting for coronary artery disease.

METHODS

Patients with OSA who underwent both polysomnography testing and exercise stress echocardiogram were selected. Records were reviewed retrospectively for demographics, comorbidities, stress echocardiographic parameters, and polysomnography data. Univariable and multivariable logistic regression analysis was used to evaluate the association between IFC and overall mortality. We then evaluated the variables associated with IFC in the overall population and in the subgroup with normal Duke treadmill score (DTS).

RESULTS

In our cohort, 404 (26%) patients had IFC. The best predictors of IFC were female sex, history of smoking, ejection fraction less than 55, increased body mass index, presence of comorbidities, abnormal exercise echocardiogram, abnormal heart rate recovery, and abnormal DTS. Compared with those without IFC, patients with IFC were 5.1 times more likely to die (odds ratio [OR], 5.1; 95% confidence interval [CI], 2.5-10.5; P < 0.0001) by univariate analysis and 2.7 times more likely to die (OR, 2.7; 95% CI, 1.2-6.1; P = 0.02) by multivariate analysis, when accounting for heart rate recovery, DTS, and sleep apnea severity. Among those without coronary artery disease, patients with IFC were at significantly increased risk of mortality (OR, 4.3; 95% CI, 1.35-13.79; P = 0.0088) compared with those with preserved functional capacity.

CONCLUSIONS

In our OSA population, IFC was a strong predictor of increased mortality. Among those with normal DTS, IFC identified a cohort at increased risk of mortality.

Principles of rehabilitation and reactivation: interstitial lung disease, sarcoidosis and rheumatoid disease with respiratory involvement

The interstitial lung diseases (ILDs) are characterised by dyspnoea on exertion, exercise-induced hypoxaemia, reduced skeletal muscle function and exercise intolerance. Evidence from nine randomised controlled trials shows that pulmonary rehabilitation improves exercise capacity, dyspnoea and quality of life in ILD, with moderately large effect sizes from 0.59 to 0.68. Participants with idiopathic pulmonary fibrosis, the most common and most progressive of the ILDs, achieve benefits in exercise capacity and quality of life that are of equal magnitude to those seen in other ILDs, with effect sizes from 0.59 to 0.75. Whole body exercise training is a core component of pulmonary rehabilitation for ILD. The standard exercise prescription used for other chronic lung diseases is effective in ILD, including 8 weeks of training with at least two supervised sessions per week and at least 30 min of aerobic training per session. However, the unique presentation and underlying pathophysiology of ILD may require modifications of the exercise prescription for individual patients. Those with connective tissue disease may present with joint pain and stiffness that require modification of the standard exercise prescription, including reduction in weight-bearing exercise. Some patients with severe disease may present with distressing dyspnoea that limits the intensity or progression of training. Because exercise-induced hypoxaemia is common in ILD and more severe than seen in other chronic lung diseases, pulmonary rehabilitation should be provided in a setting where supplemental oxygen therapy is available. Pulmonary rehabilitation programs offer the opportunity to address other critical aspects of ILD care, including management of comorbidities, symptoms and mood.

Heart rate recovery and survival in patients undergoing stereotactic body radiotherapy for treatment of early-stage lung cancer

OBJECTIVES

Up to 25% of patients with stage I non-small cell lung cancer (NSCLC) are considered high-risk for surgery, due to severe medical comorbidity and/or poor pulmonary reserve. Many of these patients are treated with stereotactic body radiotherapy (SBRT). Prognosis in this subgroup of patients is difficult to determine. We investigated the association of impaired heart rate recovery (HRR) with survival in patients who received SBRT for treatment of early-stage lung cancer.

METHODS

We collected data from consecutive patients who, between October 2009 and December 2012, received SBRT for treatment of lung cancer at the Cleveland Clinic, and had 6-minute walk test (6MWT) followed by HRR evaluation performed within six months of initiation of treatment. Impaired HRR was defined as a ≤ 12 beat decrease within the first minute following the 6MWT. Survival analyses were performed using Kaplan-Meier estimates and Cox proportional hazard ratios.

RESULTS

Forty nine patients who received SBRT for treatment of early-stage lung cancer had HRR data available. Thirty two (65%) patients had impaired HRR following the 6MWT. In univariable and multivariable Cox regression analyses, impaired HRR was associated with poorer survival (HR: 11.0, 95% CI: 1.42 - 84.4, p = 0.004, and HR: 15.8, 95% CI: 1.96 - 128.0, p = 0.010, respectively). The 2-year overall survival rates were 52.6% for those with impaired HRR, and 94.1% for those with normal HRR.

CONCLUSION

Impaired HRR was associated with poorer survival in patients who received SBRT for treatment of early-stage lung cancer. HRR following the 6MWT can be one of the factors considered in patient selection for treatment with SBRT, along with other medical comorbidities.

An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease

Field walking tests are commonly employed to evaluate exercise capacity, assess prognosis and evaluate treatment response in chronic respiratory diseases. In recent years, there has been a wealth of new literature pertinent to the conduct of the 6-min walk test (6MWT), and a growing evidence base describing the incremental and endurance shuttle walk tests (ISWT and ESWT, respectively). The aim of this document is to describe the standard operating procedures for the 6MWT, ISWT and ESWT, which can be consistently employed by clinicians and researchers. The Technical Standard was developed by a multidisciplinary and international group of clinicians and researchers with expertise in the application of field walking tests. The procedures are underpinned by a concurrent systematic review of literature relevant to measurement properties and test conduct in adults with chronic respiratory disease. Current data confirm that the 6MWT, ISWT and ESWT are valid, reliable and responsive to change with some interventions. However, results are sensitive to small changes in methodology. It is important that two tests are conducted for the 6MWT and ISWT. This Technical Standard for field walking tests reflects current evidence regarding procedures that should be used to achieve robust results.

An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease

This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.

Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.

The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.

The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.

Respiratory disease and respiratory physiology: putting lung function into perspective interstitial lung disease

The interstitial lung diseases pathologically involve the pulmonary interstitium but may also involve the airways, pleura and pulmonary circulation. They may be idiopathic, be part of other conditions, or be related to drug or environmental exposures. This review will focus on diagnostic and prognostic information provided by lung function tests in the idiopathic interstitial pneumonias, particularly idiopathic pulmonary fibrosis and non-specific interstitial pneumonia. These disorders are characterized by small stiff lungs with impaired gas exchange. Lung function tests, particularly lung volumes and gas transfer, used initially on patient presentation and then repeatedly on follow up, together with high-resolution computed tomography scans, can generate predictive formulae which are superior to single tests and can be used to provide useful information to assess the natural history of the disease or guide therapy. The concomitant presence of emphysema may mask the degree of restriction and may have adverse prognostic implications when accompanied by pulmonary hypertension.

Treatment of pulmonary hypertension in idiopathic pulmonary fibrosis: shortfall in efficacy or trial design?

Idiopathic pulmonary fibrosis (IPF) is a disease that carries a high mortality. Pulmonary hypertension (PH) frequently complicates the course of patients with IPF and is associated with significantly worse outcomes. Whether PH is a surrogate or driver of these worse outcomes remains unanswered, but the presence of PH represents an attractive target for therapy. This review delves into the various pulmonary vasoactive agents that have been subjected to study in IPF, the pitfalls of some of these prior studies, and attempts to lay a foundation for future study designs targeting PH in IPF.

Heart rate recovery post 6-minute walking test in obstructive sleep apnea: cycle ergometry versus 6-minute walking test in OSA patients

PURPOSE

To examine the clinical usefulness of heart rate recovery (HRR) post 6-minute walking test (6MWT) as a simple marker of cardiovascular risk in obstructive sleep apnea (OSA) patients in comparison to HRR post cycle ergometry, the validated and more sophisticated protocol.

METHODS

Seventy-four participants underwent full overnight polysomnography, cycle ergometry and 6MWT. The HRR at 1, 2 and 3 min (HRR-1, HRR-2 and HRR-3) 6MWT was compared to HRR at 1, 2, and 3 min post cycle ergometry in normal subjects and in moderate and severe OSA patients before and after 6-month CPAP treatment.

RESULTS

The HRR-1, HRR-2 and HRR-3 in 6MWT were significantly different between normal, moderate and severe OSA patients with higher rates achieved in normal. The higher the severity of OSA the lower the HRR was. There were also no differences found between work rate and distance walked during cycle ergometry or 6MWT, respectively, concerning normal, moderate and severe OSA patients. Heart rate recovery was further associated with minimum saturation of oxygen during sleep independently of the duration of apnea episodes of BMI and ESS. The treatment with CPAP had a beneficial effect on HRR both post-6MWT and post cycle ergometry.

CONCLUSIONS

Autonomic nervous system dysfunction in OSA can be found even with submaximal exertion. Heart rate recovery post-6MWT, such as HRR post cycle ergometry, was significantly impaired in OSA patients in comparison to normals and was favorably influenced from CPAP treatment. Furthermore, it was found to be more sensitive compared with distance walked in 6MWT in discriminating severity of OSA. The HRR post-6MWT was found to be an easily measured and reliable marker of OSA severity both before and after CPAP treatment.

The red cell distribution width as a prognostic indicator in idiopathic pulmonary fibrosis

BACKGROUND

The course of idiopathic pulmonary fibrosis (IPF) is characterized by variable patterns of disease progression. The red cell distribution width (RDW) is a parameter that is routinely reported with all CBC counts. We sought to test the prognostic usefulness of this parameter in a well-defined cohort of patients with IPF.

METHODS

CBCs, demographics, and pulmonary function data from patients with IPF evaluated between January 1997 and June 2011 were collated. Patient outcomes were ascertained from the program's database and the Social Security Death Index.

RESULTS

There were 319 patients with IPF evaluated in whom baseline CBCs were available. The range in the RDW was 11.9 to 21.9 (median 14.1). There were 228 subjects with RDW values ≤ 15 (normal) and 91 patients with RDW values &gt; 15. Patients with normal RDW values had a median survival of 43.1 months compared with 16.3 months for those whose RDW was &gt; 15 (P = .001). There were 198 patients with available serial RDW data. Those patients who had a change in the RDW of less or greater than +0.010/mo had median survivals of 43.0 and 23.9 months, respectively (P = .0246).

CONCLUSIONS

The RDW is a readily available laboratory test result that may provide important, independent prognostic information at baseline and follow-up in patients with IPF. Further studies are warranted to validate this as a biomarker for IPF outcomes, as well as to define the biologic basis for this association.

Pulmonary rehabilitation in patients with idiopathic pulmonary fibrosis--a review

Among the various types of interstitial lung diseases, idiopathic pulmonary fibrosis (IPF) is the most common disorder and has a poor prognosis and a limited response to pharmacological treatment. In patients with IPF, functional exercise tolerance and quality of life have been shown to be significantly decreased. Current IPF guidelines suggest only a weak recommendation for pulmonary rehabilitation (PR). However, PR is regarded as a reasonable choice for the majority of patients with IPF. This review will summarize all of the available studies that have investigated the effects of PR in patients with IPF so far. Although only a small number of studies have been published to date, most studies have found significant short-term improvements in functional exercise capacity, quality of life, and level of perceived dyspnea. Long-term improvements or maintenance strategies of PR in IPF patients have not been adequately investigated yet. Up to now there is still no sufficient evidence for the recommendation of PR in IPF. However, physical training seems to be the major component of all PR programs. The current review will discuss potential exercise training regimens for patients with IPF and suggest additional useful modalities of a specific multidisciplinary PR program for IPF patients. Based on the current literature and our own experience, this article will try to highlight the importance of PR as an additional, beneficial therapeutic option for patients with IPF.