Predictive significance of the six-minute walk distance for long-term survival in chronic hypercapnic respiratory failure

Background: The 6-min walk distance ( 6-MWD) is a global marker of functional capacity and prognosis in chronic obstructive pulmonary disease ( COPD), but less explored in other chronic respiratory diseases. Objective: To study the role of 6-MWD in chronic hypercapnic respiratory failure ( CHRF). Methods: In 424 stable patients with CHRF and non-invasive ventilation ( NIV) comprising COPD ( n = 197), restrictive diseases ( RD; n = 112) and obesity-hypoventilation- syndrome ( OHS; n = 115), the prognostic value of 6-MWD for long- term survival was assessed in relation to that of body mass index (BMI), lung function, respiratory muscle function and laboratory parameters. Results: 6-MWD was reduced in patients with COPD ( median 280 m; quartiles 204/350 m) and RD ( 290 m; 204/362 m) compared to OHS ( 360 m; 275/440 m; p <0.001 each). Overall mortality during 24.9 (13.1/40.5) months was 22.9%. In the 424 patients with CHRF, 6-MWD independently predicted mortality in addition to BMI, leukocytes and forced expiratory volume in 1 s ( p <0.05 each). In COPD, 6-MWD was strongly associated with mortality using the median {[} p <0.001, hazard ratio ( HR) = 3.75, 95% confidence interval (CI): 2.24-6.38] or quartiles as cutoff levels. In contrast, 6-MWD was only significantly associated with impaired survival in RD patients when it was reduced to 204 m or less (1st quartile; p = 0.003, HR = 3.31, 95% CI: 1.73-14.10), while in OHS 6-MWD had not any prognostic value. Conclusions: In patients with CHRF and NIV, 6-MWD was predictive for long- term survival particularly in COPD. In RD only severely reduced 6-MWD predicted mortality, while in OHS 6-MWD was relatively high and had no prognostic value. These results support a disease-specific use of 6-MWD in the routine assessment of patients with CHRF. Copyright (C) 2007 S. Karger AG, Basel

Effect of inspiratory pressure support on exercise performance in patients with chronic obstructive pulmonary disease

Title: Effect of inspiratory pressure support on exercise performance in patients with chronic obstructive pulmonary disease. Purpose: This study examined the effects of a non-invasive ventilator on submaximal and maximal exercise performance in patients with chronic obstructive pulmonary disease (COPD). Methods: Fourteen men (66.0 ± 7.4yr) and six women (59.0 ± 7.4yr) with a diagnosis of COPD, a forced expiratory volume! (FEVi) <40%, and the ability to tolerate 12 cmH20 of pressure on a non- invasive ventilator performed two maximal exercise tests on a cycle ergometer, with and without ventilatory assistance prior to exercise. Blood samples, respiratory metabolic measures, heart rate and rating of perceived exertion (RPE) were obtained throughout each exercise test. Results: Peak work rate (W), total exercise time, and respiratory rate were higher (p<0.05) when exercise was preceded by ventilatory support compared to no support. There was no difference in peak oxygen uptake (V02), carbon dioxide (VC02,), heart rate (HR), minute ventilation (VE), tidal volume (VT), blood lactate or RPE between the two experimental conditions. A total of 12 subjects completed at least 5 stages of the exercise protocol, and their physiological response during exercise with NIV and without NIV were compared. RPE was significantly lower during the first 3 min in the NIV condition than the no NIV condition. Circulating levels of blood lactate were lower (p<0.01) during stage 3 in the NIV than the than no NIV condition. There was no difference in RR, VT, HR, %HR, VE, V 0 2and %V02 between the two experimental conditions during sub maximal exercise. Conclusions: Application of non-invasive ventilatory support prior to exercise improves maximal exercise performance, but has no effect on cardio-metabolic response during submaximal exercise in patients with COPD

Restoring Functional Status: A Long-Term Case Report of Severe Lung and Ventilatory Muscle Pump Dysfunction Involving Recurrent Bacterial Pneumonias

Background and Purpose: Prolonged mechanical ventilation contributes to immobility and deconditioning making efforts to safely discontinue ventilator support desirable. This case report documents how implementing physical therapy treatment interventions, based on the Guide to Physical Therapist Practice, can help to restore a person’s functional status even after multiple years of mechanical ventilation dependency. Case Description: A patient (female; aged 63 years) with severe restrictive and obstructive ventilatory impairment has survived 34 recurrent pneumonias involving 6 bacterial pathogens while being mechanically ventilated at home. A 3-year study was approved and informed consent obtained for a home exercise program of resistive extremity and inspiratory muscle training along with exercise reconditioning. Tolerable distances walked, maximal inspiratory and expiratory pressures, hours spent on versus off mechanical ventilation, activities performed within and around her home, and community excursions taken were charted. Outcomes: Daily time tolerated off the ventilator improved from less than one to 12 hours, distance walked in 6 minutes increased 33%, and maximal inspiratory and expiratory pressures improved 62% and 9.6% respectively. These improvements made out-of-home social excursions possible. Discussion and Conclusions: This patient’s functional status improved following multiple physical therapy interventions dictated by the evaluation of initial physical therapy examination findings according to the Guide to Physical Therapist Practice. Long term mechanical ventilator dependency in the home environment did not exclude this patient from achieving clinically significant gains in functional status even when having severe restrictive and obstructive ventilator impairment

Inspiration for the Future: The Role of Inspiratory Muscle Training in Cystic Fibrosis.

Cystic fibrosis (CF) is an inherited, multi-system, life-limiting disease characterized by a progressive decline in lung function, which accounts for the majority of CF-related morbidity and mortality. Inspiratory muscle training (IMT) has been proposed as a rehabilitative strategy to treat respiratory impairments associated with CF. However, despite evidence of therapeutic benefits in healthy and other clinical populations, the routine application of IMT in CF can neither be supported nor refuted due to the paucity of methodologically rigorous research. Specifically, the interpretation of available studies regarding the efficacy of IMT in CF is hampered by methodological threats to internal and external validity. As such, it is important to highlight the inherent risk of bias that differences in patient characteristics, IMT protocols, and outcome measurements present when synthesizing this literature prior to making final clinical judgments. Future studies are required to identify the characteristics of individuals who may respond to IMT and determine whether the controlled application of IMT can elicit meaningful improvements in physiological and patient-centered clinical outcomes. Given the equivocal evidence regarding its efficacy, IMT should be utilized on a case-by-case basis with sound clinical reasoning, rather than simply dismissed, until a rigorous evidence-based consensus has been reached

Correspondence: British Thoracic Society guideline on pulmonary rehabilitation in adults: Does objectivity have a sliding scale?

This article is made available through the Brunel Open Access Publishing Fund. Copyright © 2014 BMJ Publishing Group Ltd & British Thoracic Society. This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is noncommercial. See: http://creativecommons.org/licenses/ by-nc/3.0/No abstract available (Letter

Proprioceptive changes impair balance control in individuals with chronic obstructive pulmonary disease

Copyright @ 2013 Janssens et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Introduction: Balance deficits are identified as important risk factors for falling in individuals with chronic obstructive pulmonary disease (COPD). However, the specific use of proprioception, which is of primary importance during balance control, has not been studied in individuals with COPD. The objective was to determine the specific proprioceptive control strategy during postural balance in individuals with COPD and healthy controls, and to assess whether this was related to inspiratory muscle weakness. Methods: Center of pressure displacement was determined in 20 individuals with COPD and 20 age/gender-matched controls during upright stance on an unstable support surface without vision. Ankle and back muscle vibration were applied to evaluate the relative contribution of different proprioceptive signals used in postural control. Results: Individuals with COPD showed an increased anterior-posterior body sway during upright stance (p=0.037). Compared to controls, individuals with COPD showed an increased posterior body sway during ankle muscle vibration (p=0.047), decreased anterior body sway during back muscle vibration (p=0.025), and increased posterior body sway during simultaneous ankle-muscle vibration (p=0.002). Individuals with COPD with the weakest inspiratory muscles showed the greatest reliance on ankle muscle input when compared to the stronger individuals with COPD (p=0.037). Conclusions: Individuals with COPD, especially those with inspiratory muscle weakness, increased their reliance on ankle muscle proprioceptive signals and decreased their reliance on back muscle proprioceptive signals during balance control, resulting in a decreased postural stability compared to healthy controls. These proprioceptive changes may be due to an impaired postural contribution of the inspiratory muscles to trunk stability. Further research is required to determine whether interventions such as proprioceptive training and inspiratory muscle training improve postural balance and reduce the fall risk in individuals with COPD.This work was supported by the Research Foundation – Flanders (FWO) grants 1.5.104.03, G.0674.09, G.0598.09N and G.0871.13N

Surface mechanomyography and electromyography provide non-invasive indices of inspiratory muscle force and activation in healthy subjects

The current gold standard assessment of human inspiratory muscle function involves using invasive measures of transdiaphragmatic pressure (Pdi) or crural diaphragm electromyography (oesEMGdi). Mechanomyography is a non-invasive measure of muscle vibration associated with muscle contraction. Surface electromyogram and mechanomyogram, recorded transcutaneously using sensors placed over the lower intercostal spaces (sEMGlic and sMMGlic respectively), have been proposed to provide non-invasive indices of inspiratory muscle activation, but have not been directly compared to gold standard Pdi and oesEMGdi measures during voluntary respiratory manoeuvres. To validate the non-invasive techniques, the relationships between Pdi and sMMGlic, and between oesEMGdi and sEMGlic were measured simultaneously in 12 healthy subjects during an incremental inspiratory threshold loading protocol. Myographic signals were analysed using fixed sample entropy (fSampEn), which is less influenced by cardiac artefacts than conventional root mean square. Strong correlations were observed between: mean Pdi and mean fSampEn |sMMGlic| (left, 0.76; right, 0.81), the time-integrals of the Pdi and fSampEn |sMMGlic| (left, 0.78; right, 0.83), and mean fSampEn oesEMGdi and mean fSampEn sEMGlic (left, 0.84; right, 0.83). These findings suggest that sMMGlic and sEMGlic could provide useful non-invasive alternatives to Pdi and oesEMGdi for the assessment of inspiratory muscle function in health and disease.Peer ReviewedPostprint (published version

The effects of lung volume on swallowing in chronic obstructive pulmonary disease

Chronic Obstructive Pulmonary Disease (COPD), a respiratory disease that leads to reduced airflow, may result in difficulty swallowing with disease progression. The coordination between the respiratory and swallowing systems decouple and they may experience increased risk of aspiration. This study aimed to determine the effects of lung volume on swallowing in individuals with COPD compared with older healthy. Specifically, the study examined if altering lung volume at the time of the swallow changed swallowing timing, specifically pharyngeal swallow duration, and impacted the respiratory-swallow pattern in individuals with COPD. Measurement of estimated lung volume (ELV), pharyngeal swallow duration, and respiratory-swallow patterning in individuals with COPD was compared with older healthy at varying lung volume conditions. Participants completed seven 20 ml water bolus swallows by medicinal cup across 4 lung volumes: non-cued volume (NC), and in order of increasing volume, resting expiratory level (REL), tidal volume (TV), and total lung capacity (TLC) . ELV was determined using respiratory inductive plethysmography (RIP) and spirometry. Swallow timing was measured by events during the swallow with pharyngeal manometry. Individuals with COPD had lower lung volumes at the time of the swallow than older healthy individuals. A moderate to strong negative relationship between estimated lung volume at the time of the swallow and pharyngeal swallow duration was found in individuals with COPD that was not present in the healthy participants. They had a longer pharyngeal duration when swallowing at lower lung volumes. The percentage of swallows resuming on inspiration post-swallow were significantly greater in individuals with COPD than the healthy. In the COPD group, resumption of respiration in inspiration occurred significantly less often at the higher lung volumes (TLC and TV) than the lower volume condition, REL. In conclusion lower lung volumes at the time of the swallow in individuals with COPD were associated with longer pharyngeal swallow duration and increased resumption of respiration in inspiration post-swallow

Strategy for respiratory exercise pattern associated with upper limb movements in COPD patients

INTRODUCTION: Upper limb exercises are frequently used in respiratory physiotherapy, with UL elevation and controlled inspiratory timing. However, the use of expiration during upper limb elevation appears to be a strategy that could minimize the action of accessory muscles in patients with chronic obstructive pulmonary disease. In this context, little is known about the synchrony of upper limb (UL) movements associated with breathing. The aim of this study was to investigate the respiratory pattern of chronic obstructive pulmonary disease patients during different UL exercises associated with respiratory exercises. METHODS: Fifteen chronic obstructive pulmonary disease patients participated in this study. Respiratory pattern analysis by inductance plethysmography was performed during four types of upper limb exercises, two shoulder flexion-extension (one associated with inspiratory time during the concentric phase and the other associated with expiratory time) and two shoulder abduction-adduction (same timing as above). Statistical analysis was performed by the Kolmogorov-Smirnov test and ANOVA with Tukey tests (p< 0.05). RESULTS: The thoracoabdominal coordination measurements increased in the two exercises using both inspiration during shoulder flexion (PhRIB: 172%; PhREB: 131%; PhRTB: 142% and PhAng: 238%) as well as in shoulder horizontal abduction (PhRIB: 145%; PhREB: 109%; PhRTB: 130% and PhAng: 229%), differing from the exercises with expiration at the time of shoulder flexion and horizontal abduction. CONCLUSION: The exercises performed with inverted respiratory time produced less asynchrony and can be used as important strategies during physical exercise programs in these patients

Work of breathing in exercise and disease

This thesis is focussed on developing new methods and outcomes to assess respiratory function that require little or no volitional effort on behalf of the participants being tested. Specifically to attempt to detach the behaviour of the patient from the accuracy of the test of respiratory function, resulting in techniques that are simpler and easier to administer and undertake for both assessor and participant. It aims to develop methods that reduce the involvement of the participant during assessment of respiratory function. The human body’s way of controlling respiration has evolved into a sophisticated system that optimises breathing pattern to maintain the most efficient homeostatic action of the respiratory system. Eliciting and assessing this automatic response is the key to removing the action of participation from respiratory functiontesting. The focus must therefore be on developing non-invasive, sub-maximal techniques that allow participants to enter into a steady state of respiration and how this can be assessed. Two techniques were investigated; Respiratory Endurance (as the inspiratory work of breathing) and Tidal Breathing Flow Profile, and these were successfully applied in 99 adult participants (68 healthy controls and 31 COPD patients) and 75 children (48 clinical group and 27 healthy controls) who completed 467 respiratory endurance trials whilst seated and exercising, and 249 relaxed tidal breathing trials. The difficulties with lung function assessment are well established and have been described in this thesis. Much recent emphasis has been put on developing existing devices and protocols rather than developing new techniques and approaching these difficulties from alternative viewpoints. This thesis has described the development of innovative techniques to assess the function of the respiratory systems that aim to overcome the issues associated with maximal testing. It was shown that these techniques are easy to undertake for a range of participants, simple to analyse and are able to reliably differentiate between health and disease, suggesting that they could become a useful adjunct to existing methods of respiratory assessment