Change In Inspiratory Capacity Research Articles

Effects of Obesity and Sex on Ventilatory Constraints during a Cardiopulmonary Exercise Test in Children.

Ventilatory constraints are common during exercise in children, but the effects of obesity and sex are unclear. The purpose of this study was to investigate the effects of obesity and sex on ventilatory constraints (i.e., expiratory flow limitation (EFL) and dynamic hyperinflation) during a maximal exercise test in children. Thirty-four 8- to 12-yr-old children without obesity (18 females) and 54 with obesity (23 females) completed pulmonary function testing and maximal cardiopulmonary exercise tests. EFL was calculated as the overlap between tidal flow-volume loops during exercise and maximal expiratory flow-volume loops. Dynamic hyperinflation was calculated as the change in inspiratory capacity from rest to exercise. Maximal minute ventilation was not different between children with and without obesity. Average end-inspiratory lung volumes (EILV) and end-expiratory lung volumes (EELV) were significantly lower during exercise in children with obesity (EILV: 68.8% ± 0.7% TLC; EELV: 41.2% ± 0.5% TLC) compared with children without obesity (EILV: 73.7% ± 0.8% TLC; EELV: 44.8% ± 0.6% TLC; P < 0.001). Throughout exercise, children with obesity experienced more EFL and dynamic hyperinflation compared with those without obesity ( P < 0.001). Also, males experienced more EFL and dynamic hyperinflation throughout exercise compared with females ( P < 0.001). At maximal exercise, the prevalence of EFL was similar in males with and without obesity; however, the prevalence of EFL in females was significantly different, with 57% of females with obesity experiencing EFL compared with 17% of females without obesity ( P < 0.05). At maximal exercise, 44% of children with obesity experienced dynamic hyperinflation compared with 12% of children without obesity ( P = 0.002). Obesity in children increases the risk of developing mechanical ventilatory constraints such as dynamic hyperinflation and EFL. Sex differences were apparent with males experiencing more ventilatory constraints compared with females.

Impact of bronchoscopic lung volume reduction with endobronchial valves on dynamic hyperinflation: Results from the PIERCE study.

Dynamic hyperinflation (DH) is a major marker of exertional dyspnoea in severe emphysema. We hypothesized that bronchoscopic lung volume reduction (BLVR) using endobronchial valves (EBVs) decreases DH. In this prospective bi-centre study from both Toulouse and Limoges Hospitals, we assessed DH during an incremental cycle ergometry before and 3months after EBVs treatment. The primary objective was to observe the change in inspiratory capacity (IC) at isotime. Target lobe volume reduction (TLVR) and changes in residual volume (RV), forced expiratory volume in one-second (FEV1 ), mMRC, 6minutes walking distance (6MWD), BODE and other dynamic measures like tele-expiratory volume (EELV) were also analysed. Thirty-nine patients were included, of whom thirty-eight presented DH. IC and EELV at isotime significantly improved (+214 mL, p= 0.004; -713 mL, p˂0.001, respectively). Mean changes were +177 mL for FEV1 (+19%, p< 0.001), -600 mL for RV (p< 0.0001), +33 m for 6MWD (p< 0.0001), respectively. Patients who responded on RV (>430 mL decrease) and FEV1 (>12% gain) had better improvements compared to non-responders (+368 mL vs. +2mL; +398 mL vs. -40 mL IC isotime, respectively). On the opposite, in patients who responded on DH (>200 mL IC isotime increase), changes in TLV (-1216 mL vs. -576 mL), FEV1 (+261 mL vs. +101 mL), FVC (+496 mL vs. +128 mL) and RV (-805 mL vs. -418 mL) were greater compared to non-responders. DH decreases after EBVs treatment, and this improvement is correlated with static changes.

A Trial of Adding Lung Protective Strategies to Existing Enhanced Recovery After Surgery Protocols and Its Effect on Improving Postoperative Lung Function.

With this rising popularization of enhanced recovery after surgery (ERAS) protocols, it is important to ask if the current and developing pathways are fully comprehensive for the patient's perioperative experience. Many current pathways discuss aspects of care including fluid management, pain management, and anti-emetic medication regiments, but few delineate recommendations for lung protective strategies. The hypothesis was that intraoperative lung protective strategies would results in improved postoperative lung function. One hundred patients at the Medical University of South Carolina undergoing hepatobiliary and colorectal surgeries were randomized to receive intraoperative lung protective techniques or a standard intraoperative ventilation management. Three maximum vital capacity breaths were recorded preoperatively, and postoperatively 30 min, 1 h, and 2 h after anesthesia stop time. Average maximum capacity breaths from all four data collection interactions were analyzed between both study and control cohorts. There was no significant difference in the preoperative inspiratory capacity between the control and the ERAS group (2,043.3 ± 628.4 mL vs. 2,012.2 ± 895.2 mL; P = 0.84). Additional data analysis showed no statistically significant difference between ERAS and control groups: total average of the inspiratory capacity volumes (1,253.5 ± 593.7 mL vs. 1,390.4 ± 964.9 mL; P = 0.47), preoperative oxygen saturation (97.76±2.3% vs. 98.04±1.7%; P = 0.50), the postoperative oxygen saturation (98.51±1.4% vs. 96.83±14.2%; P = 0.40), and change in inspiratory capacity (95% confidence interval (CI) (-211.2 - 366.6); P = 0.60). No statistically significant difference in postoperative inspiratory capacities were seen after the implementation of intraoperative lung protective strategies. The addition of other indicators of postoperative lung function like pneumonia incidence or length of inpatient stay while receiving oxygen treatment could provide a fuller picture in future studies, but a higher power will be needed.

Effects of Sarcopenia on Ventilatory Behavior and the Multidimensional Nature of Dyspnea in Patients With Chronic Obstructive Pulmonary Disease

ObjectivesThis study tested the hypothesis that sarcopenia, a common extrapulmonary feature of chronic obstructive pulmonary disease (COPD), can affect ventilatory behavior, and worsen the multidimensional nature of dyspnea in patients with COPD. DesignCross-sectional survey study. Settingand Participants: Stable outpatients with COPD encountered in general practice and respiratory clinic. MethodSarcopenia was diagnosed according to an appendicular skeletal muscle mass index based on measurements of electrical impedance and handgrip strength. Exertional dyspnea was tested using a 3-minute Step Test and a 6-minute Walk Test. The dimensions of dyspnea were assessed by a multidimensional dyspnea profile. ResultsOf 60 stable patients with COPD, 16 met the criteria for sarcopenia. During the 3-minute Step Test, minute ventilation as a proportion of exercise time, tidal volume as a proportion of inspiratory capacity, the change in inspiratory capacity, and ventilation as a proportion of maximal voluntary ventilation did not differ between patients with and without sarcopenia. Patients with sarcopenia exhibited lower evolution of tidal volume, higher evolution of respiratory frequency versus ventilation and breathing discomfort on the 3-minute Step Test, as well as increased physical breathing effort on the 6-minute Walk Test, compared with those without sarcopenia. In a multivariable model adjusted using inverse probability weighting, sarcopenia was independently associated with breathing discomfort during the 3-minute Step Test and physical breathing effort during the 6-minute Walk Test. Conclusions and ImplicationsSarcopenia may be associated with shallow breathing and diverse sensory and affective components of exertional dyspnea in patients with COPD. The study indicates that improvement of the rapid breathing pattern may offer unique ways to alleviate dyspnea in older patients with COPD and sarcopenia.

Diaphragmatic excursion correlates with exercise capacity and dynamic hyperinflation in COPD patients.

BackgroundAlthough the pathophysiological mechanisms involved in the development of dyspnoea and poor exercise tolerance in patients with COPD are complex, dynamic lung hyperinflation (DLH) plays a central role. Diaphragmatic excursions can be measured by ultrasonography (US) with high intra- and interobserver reliability. The objective of this study was to evaluate the effect of diaphragmatic excursions as assessed by US on exercise tolerance and DLH in patients with COPD.MethodsPatients with COPD (n=20) and age-matched control subjects (n=20) underwent US, which was used to determine the maximum level of diaphragmatic excursion (DEmax). Ventilation parameters, including the change in inspiratory capacity (ΔIC), were measured in the subjects during cardiopulmonary exercise testing (CPET). We examined the correlations between DEmax and the ventilation parameters.ResultsThe DEmax of patients with COPD was significantly lower than that of the controls (45.0±12.8 mm versus 64.6±6.3 mm, respectively; p<0.01). The perception of peak dyspnoea (Borg scale) was significantly negatively correlated with DEmax in patients with COPD. During CPET, oxygen uptake/weight (V′O2/W) and minute ventilation (V′E) were significantly positively correlated with DEmax, while V′E/V′O2 and V′E/carbon dioxide output (V′CO2) were significantly negatively correlated with DEmax in patients with COPD. DEmax was also significantly positively correlated with ΔIC, reflecting DLH, and with V′O2/W, reflecting exercise capacity.ConclusionReduced mobility of the diaphragm was related to decreased exercise capacity and increased dyspnoea due to dynamic lung hyperinflation in COPD patients.

Change in Dynamic Hyperinflation After Bronchoscopic Lung Volume Reduction in Patients with Emphysema

Background and PurposeIn patients with severe emphysema, dynamic hyperinflation is superimposed on top of already existing static hyperinflation. Static hyperinflation reduces significantly after bronchoscopic lung volume reduction (BLVR). In this study, we investigated the effect of BLVR compared to standard of care (SoC) on dynamic hyperinflation.MethodsDynamic hyperinflation was induced by a manually paced tachypnea test (MPT) and was defined by change in inspiratory capacity (IC) measured before and after MPT. Static and dynamic hyperinflation measurements were performed both at baseline and 6 months after BLVR with endobronchial valves or coils (treatment group) or SoC (control group).ResultsEighteen patients underwent BLVR (78% female, 57 (43–67) years, FEV1 25(18–37) %predicted, residual volume 231 (182–376) %predicted). Thirteen patients received SoC (100% female, 59 (44–74) years, FEV1 25 (19–37) %predicted, residual volume 225 (152–279) %predicted. The 6 months median change in dynamic hyperinflation in the treatment group was: + 225 ml (range − 113 to + 803) (p < 0.01) vs 0 ml (− 1067 to + 500) in the control group (p = 0.422). An increase in dynamic hyperinflation was significantly associated with a decrease in residual volume (r = − 0.439, p < 0.01).ConclusionBronchoscopic lung volume reduction increases the ability for dynamic hyperinflation in patients with severe emphysema. We propose this is a consequence of improved static hyperinflation.

Small airway dysfunction predicts excess ventilation and dynamic hyperinflation during exercise in patients with COPD

IntroductionSmall airway dysfunction (SAD) is a pathophysiological characteristic of chronic obstructive pulmonary disease (COPD). Excess ventilation and dynamic hyperinflation (DH) are two main pathophysiological traits and limiting factors of COPD patients while exercising. We aimed to ascertain whether or not SAD, assessed by the multiple breath nitrogen washout (MBNW), may predict exercise ventilatory inefficiency and DH. MethodsFifty stable COPD patients were prospectively studied and underwent MBNW and incremental cardio-pulmonary exercise test (CPET). Indices of conductive (Scond) and acinar (Sacin) ventilation heterogeneity as well as minute ventilation/CO2 production (VE/VCO2) linear relationship and the change in inspiratory capacity (IC) were analyzed. ResultsSacin was significantly and directly related to VE/VCO2 slope and inversely related to IC change and to peak O2 uptake (p < 0.01 for all correlations). No significant correlation was found between Scond and CPET parameters. The regression equation generated by stepwise multiple regression analysis for the VE/VCO2 slope and IC change, as dependent variables, included only Sacin, as independent variable. This model accounted for 31% and 36% of the total variance for the VE/VCO2 slope and IC change, respectively. ConclusionOur study shows the value of the SAD as determinant of the excess ventilation and DH during exercise in patients with stable COPD.

Intensity and quality of exertional dyspnoea in patients with stable pulmonary hypertension.

Dynamic hyperinflation is observed during exercise in 60% of patients with clinically stable pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH), intensifying exertional dyspnoea. The impact of dynamic changes in respiratory mechanics during exercise on qualitative dimensions of dyspnoea in these patients has not been evaluated.26 patients (PAH n=17; CTEPH n=9) performed an incremental symptom-limited cycle exercise test. Minute ventilation (V'E), breathing pattern, operating lung volumes and dyspnoea intensity were assessed throughout exercise. Dyspnoea quality was serially assessed during exercise using a three-item questionnaire (dyspnoea descriptors). The inflection point of tidal volume (V T) relative to V'E was determined for each incremental test. Changes in inspiratory capacity during exercise defined two groups of patients: hyperinflators (65%) and non-hyperinflators (35%). Multidimensional characterisation of dyspnoea was performed after exercise using the Multidimensional Dyspnea Profile.In hyperinflators, inspiratory capacity decreased progressively throughout exercise by 0.36 L, while remaining stable in non-hyperinflators. The "work/effort" descriptor was most frequently selected throughout exercise in both types of patients (65% of all responses). At the V T/V'E inflection, work/effort plateaued while "unsatisfied inspiration" descriptors became selected predominantly only in hyperinflators (77% of all responses). In the affective domain, the emotion most frequently associated with dyspnoea was anxiety.In pulmonary hypertension patients who develop hyperinflation during exercise, dyspnoea descriptors referring to unsatisfied inspiration become predominant following the V T/V'E inflection. As these descriptors are generally associated with more negative emotional experiences, delaying or preventing the V T/V'E inflection may have important implications for symptom management in patients with pulmonary hypertension.

The Effect of Breathing Retraining Using Metronome-Based Acoustic Feedback on Exercise Endurance in COPD: A Randomized Trial.

During exercise-training patients with chronic obstructive pulmonary disease (COPD) can entrain their breathing pattern to visual-feedback cues as to achieve a slower respiratory rate and prolong exhalation. The result is an improvement in exercise tolerance and a reduction in dynamic hyperinflation. Acoustic stimuli, including metronome-generated acoustic stimuli, can entrain human movements. Accordingly, we hypothesized that exercise duration and dynamic hyperinflation would be less after exercise-training plus breathing-retraining using a metronome-based acoustic-feedback system than after exercise-training alone. Of 205 patients with COPD [FEV1 = 44 ± 16% predicted (± SD)] recruited, 119 were randomly assigned to exercise-training plus breathing-retraining using acoustic feedback (n = 58) or exercise-training alone (n = 61). Patients exercised on a treadmill thrice-weekly for 12weeks. Before and at completion of training, patients underwent constant-load treadmill testing with inspiratory capacity measures every 2min. At completion of training, improvements in exercise duration in the breathing-retraining plus exercise-training and exercise-training alone groups were similar (p = 0.35). At isotime, inspiratory capacity increased (less exercise-induced dynamic hyperinflation) by 3% (p = 0.001) in the breathing-retraining plus exercise-training group and remained unchanged in the exercise-alone group. The between-group change in inspiratory capacity, however, was not significant (p = 0.08). In patients with COPD, breathing-retraining using a metronome-based acoustic feedback did not result in improved exercise endurance or decreased dynamic hyperinflation when compared to exercise-training alone. ClinicalTrials.gov; No.: NCT NCT01009099; URL: http://www.clinicaltrials.gov.

Influence of Disease Severity and Exercise Limitation on Exercise Training Intensity and Load and Health Benefits From Pulmonary Rehabilitation in Patients With COPD: AN EXPLORATORY STUDY.

Some patients with chronic obstructive pulmonary disease (COPD) fail to achieve health benefits with pulmonary rehabilitation (PR). Exercise intensity and load represent stimulus for adaptation but it is unclear whether inappropriate exercise intensity and/or load are affected by severity of COPD, which may affect health benefits. The purpose was to determine whether COPD severity and/or the severity of pulmonary limitation to exercise (PLE) impacted exercising intensity or load and whether resultant intensity/load affected health outcomes derived from PR. Patients with COPD (n = 58, age = 67 ± 7 y, forced expiratory volume in the first second of expiration [FEV1] % predicted = 52 ± 21%) were recruited upon referral to PR. Primary health outcomes evaluated were 6-min walk distance and St George's Respiratory Questionnaire. Patients were stratified for disease severity using Global Initiative for Obstructive Lung Disease (GOLD) staging and PLE severity by change in inspiratory capacity during exercise. Exercise intensity and load were calculated from daily exercise records. Participants achieved comparable training duration and load regardless of GOLD severity. Patients with more severe PLE achieved greater training duration (more severe: 546 ± 143 min., less severe: 451 ± 109 min., P = .036), and relative training load (more severe: 2200.8 ± 595.3 kcal, less severe: 1648.3 ± 597.8 kcal, P = .007). Greater overall training load was associated with greater improvements in 6-min walk distance (r = 0.24, P = .035). No significant relationships were observed between PLE, GOLD severity, training parameters, and St George's Respiratory Questionnaire response. Improvements in exercise tolerance can be explained by achieving greater training loads, demonstrating the importance of appropriate training load to maximize health outcomes in PR.

Effects of respiratory rehabilitation exercise for high level of cervical spinal cord injury: Novel approach

People with high level of spinal cord injury feel a lot of discomfort in breathing ability. However, the rehabilitation exercise program to solve this problem is not activated. Also, the respiratory rehabilitation exercise program developed specifically for those is very scarce. Existing breathing exercises are uncomfortable because the method is tedious and cannot see the degree of improvement. Therefore, it is important to develop a variety of exercise programs that can effectively enhance the respiratory muscle. The purpose of this study was to investigate the effect of respiratory rehabilitation exercise to improve pulmonary function. The subject were 7 people with high level of spinal cord injury (C3-6, ASIA A, B). The exercise program developed was consist of 8 weeks of 1-h exercise session 2 days a week. Each session included warm up (stretching), respiratory rehabilitation exercise, and cool down (flexibility and relaxation). The pulmonary functions were measured with digital spirometry meter (Pony FX, Cosmed, Italy). The pulmonary function tests were conducted before and after the 16 sessions of respiratory rehabilitation exercise program. As a result of respiratory rehabilitation exercise during 8-week for subjects, pulmonary function showed significant changes in inspiratory capacity, vital capacity and inspiratory reserve volume. We confirmed the positive effect of the respiratory rehabilitation exercise program developed for people with high level of spinal cord injury. The results of this study are expected to be used as basic data for the development of specialized programs for each degree of severity.

Dynamic hyperinflation during the 6-min walk test in severely asthmatic subjects.

We tested the hypothesis that dynamic hyperinflation develops in severe asthmatic subjects during exercise. Changes in inspiratory capacity (IC) were measured during the 6-min walk test (6MWT) in severe asthmatic subjects compared with chronic obstructive pulmonary disease (COPD) subjects with a similar degree of bronchial obstruction. We assessed whether changes in IC were associated with changes in dyspnoea perception.27 severe asthmatic subjects (10 males and 17 females) and 43 COPD subjects (35 males and eight females) were recruited. The two groups performed similarly in the 6MWT (p=0.90). At the end of the test, the Borg score increased significantly in both groups (mean difference: for asthmatic subjects 1.7±1.6; p<0.0001; for COPD subjects 3.1±1.9; p<0.0001). IC measured at the beginning of 6MWT was not different between groups (2.25±0.47 L in asthmatic subjects versus 2.38±0.60 L in COPD subjects; p=0.32) and decreased in both groups (mean difference: for asthmatic subjects 0.160 L; p=0.02; for COPD subjects 0.164 L; p<0.0001). However, changes in IC were significantly associated with changes in the Borg score in the COPD group (r2=0.17; p=0.006), but not in the asthma group (r2=0.06; p=0.20).In severe asthmatic subjects, IC significantly drops during the 6MWT to the same extent as COPD subjects with a similar degree of lung impairment, indicating the development of dynamic hyperinflation. Contrary to COPD, in asthmatic subjects the occurrence of dynamic hyperinflation was not associated with changes in dyspnoea perception.

Standardized Herbal Formula PM014 Inhibits Radiation-Induced Pulmonary Inflammation in Mice

Radiation therapy is widely used for thoracic cancers. However, it occasionally causes radiation-induced lung injuries, including pneumonitis and fibrosis. Chung-Sang-Bo-Ha-Tang (CSBHT) has been traditionally used to treat chronic pulmonary disease in Korea. PM014, a modified herbal formula derived from CSBHT, contains medicinal herbs of seven species. In our previous studies, PM014 exhibited anti-inflammatory effects in a chronic obstructive pulmonary disease model. In this study, we have evaluated the effects of PM014 on radiation-induced lung inflammation. Mice in the treatment group were orally administered PM014 six times for 2 weeks. Effects of PM014 on radiation pneumonitis were evaluated based on histological findings and differential cell count in bronchoalveolar lavage fluid. PM014 treatment significantly inhibited immune cell recruitment and collagen deposition in lung tissue. Normal lung volume, evaluated by radiological analysis, in PM014-treated mice was higher compared to that in irradiated control mice. PM014-treated mice exhibited significant changes in inspiratory capacity, compliance and tissue damping and elastance. Additionally, PM014 treatment resulted in the downregulation of inflammatory cytokines, chemokines, and fibrosis-related genes and a reduction in the transforming growth factor-β1-positive cell population in lung tissue. Thus, PM014 is a potent therapeutic agent for radiation-induced lung fibrosis and inflammation.

Standardized Herbal Formula PM014 Inhibits Radiation-Induced Pulmonary Inflammation in Mice

Radiation therapy is widely used for thoracic cancers. However, it occasionally causes radiation-induced lung injuries, including pneumonitis and fibrosis. Chung-Sang-Bo-Ha-Tang (CSBHT) has been traditionally used to treat chronic pulmonary disease in Korea. PM014, a modified herbal formula derived from CSBHT, contains medicinal herbs of seven species. In our previous studies, PM014 exhibited anti-inflammatory effects in a chronic obstructive pulmonary disease model. In this study, we have evaluated the effects of PM014 on radiation-induced lung inflammation. Mice in the treatment group were orally administered PM014 six times for 2 weeks. Effects of PM014 on radiation pneumonitis were evaluated based on histological findings and differential cell count in bronchoalveolar lavage fluid. PM014 treatment significantly inhibited immune cell recruitment and collagen deposition in lung tissue. Normal lung volume, evaluated by radiological analysis, in PM014-treated mice was higher compared to that in irradiated control mice. PM014-treated mice exhibited significant changes in inspiratory capacity, compliance and tissue damping and elastance. Additionally, PM014 treatment resulted in the downregulation of inflammatory cytokines, chemokines, and fibrosis-related genes and a reduction in the transforming growth factor-β1-positive cell population in lung tissue. Thus, PM014 is a potent therapeutic agent for radiation-induced lung fibrosis and inflammation.

Chronotropic incompetence can limit exercise tolerance in COPD patients with lung hyperinflation.

PurposeMetabolic-chronotropic relationship is the only concept that assesses the entire chronotropic function during exercise, as it takes into account individual fitness. To better understand interrelationships between chronotropic incompetence (CI), dynamic hyperinflation (DH) and exercise limitation among Global initiative for chronic Obstructive Lung Disease (GOLD) stages of chronic obstructive pulmonary disease (COPD) disease severity, we evaluated cardiopulmonary responses to symptom-limited cycle exercise in stable patients.Patients and methodsWe prospectively studied 47 COPD patients classified by GOLD stage severity. Pulmonary function tests and cardiopulmonary responses to symptom-limited incremental exercise were studied. CI was defined by regression line between percent heart rate (HR) reserve and percent oxygen uptake (V’O2) reserve, ie, chronotropic-metabolic index (CMI). DH was defined from the knot resulting from the nonlinear regressions of inspiratory capacity changes from rest to peak (dynamic inspiratory capacity (ICdyn)) with percentage of maximal HR and CMI.ResultsAerobic capacity (median interquartile ranges) peak V’O2, 24.3 (23.6; 25.2), 18.5 (15.5; 21.8), 17.5 (15.4; 19.1) mL·kg−1·min−1 and CMI worsened according to GOLD severity. The optimal knot of ICdyn was equal to −0.34 L. The multivariate logistic regression showed a strong relationship between CI (outcome) and DH (odds ratio [confidence interval 95]) 25 (3.5; 191.6).ConclusionCOPD patients with DH have a poor cardiovascular response to exercise, which may be attributed to CI.

Divers’ neurobehavioral performance under 4.7 MPa: A real-time monitoring

Patients with COPD exhibit increased inspiratory work and dyspnea due to dynamic hyperinflation caused by expiratory flow limitation. Helium-oxygen mixtures (ie, heliox) have been used in treating these patients on the assumption that, by lowering airway resistance, they might be beneficial.In 22 patients with COPD, the presence of expiratory flow limitation was assessed with patients in the sitting and supine positions using the negative expiratory pressure technique, and the effects of heliox (80% He, 20% O2) on breathing pattern, expiratory flow limitation, and dynamic hyperinflation, evaluated from the change in inspiratory capacity (IC), were measured at rest and were compared with those due to inhaled salbutamol.During air breathing, 13 patients experienced flow limitation while in the sitting position and 18 experienced flow limitation while in the supine position. Neither heliox nor salbutamol therapy changed the breathing pattern in any of the patients, regardless of posture and the presence or absence of expiratory flow limitation. However, in both positions IC increased significantly in most flow-limited patients after bronchodilator administration, but not after heliox administration.Since heliox had no effect on dynamic hyperinflation, the use of this gas mixture, which is costly and cumbersome, does not appear to be beneficial in stable patients with COPD breathing at rest.

Can COPD Patients Who Hyperinflate During Daily Life Activities Be Identified by Laboratory Tests?

Background: Identification of patients with chronic obstructive pulmonary disease (COPD) who develop dynamic hyperinflation (DH) during activities in daily life (ADL) is important, because of the association between DH and dyspnea and exercise limitation. Objective: We aimed to answer the question whether measurements of DH during metronome-paced tachypnea (MPT) or cardiopulmonary exercise testing (CPET) can be used to identify patients who develop DH during ADL. Methods: DH was measured by tracking changes in inspiratory capacity during CPET, MPT and ADL. Bland-Altman plots were used to evaluate agreement in DH between methods. With a receiver operating characteristic (ROC) analysis, the overall accuracy of MPT and CPET to identify patients who hyperinflate during ADL was assessed. Results: There are broad limits of agreement in DH between methods. ROC curve analyses showed good overall accuracy of both CPET and MPT to identify patients who hyperinflate during ADL. For CPET, area under the curve (AUC) = 0.956 (95% CI 0.903-1.009). For MPT, AUC = 0.840 (95% CI 0.699-0.981). Sensitivity and specificity to identify patients who hyperinflate during ADL with CPET were 96 and 83%, respectively, and with MPT, they were 89 and 77%, respectively. Conclusion: Both CPET and MPT can serve as screening tools to identify patients who are susceptible to developing DH during ADL. In practice, MPT is the most simple and inexpensive surrogate. However, the sensitivity of MPT is not optimal. When DH does not occur during CPET, it is unlikely to occur during ADL.

Dynamic pulmonary hyperinflation occurs without expiratory flow limitation in chronic heart failure during exercise

To assess the occurrence of tidal expiratory flow limitation (EFL) and/or dynamic pulmonary hyperinflation (DH) in chronic heart failure (CHF) during exercise 15 patients with stable systolic CHF, aged 69±6yr, underwent pulmonary function testing and incremental cardio-pulmonary exercise testing. They subsequently performed constant load exercise testing at 30, 60 and 90% of respective maximum workload. At each step the presence of EFL, by negative expiratory pressure technique, and changes in inspiratory capacity (IC) were assessed. Ejection fraction amounted to 36±6% and V˙O2, peak (77±19% pred.) was reduced. EFL was absent at any step during constant load exercise. In 6 patients IC decreased more than 10% pred. at highest step. Only in these patients TLC, FRC, RV FEF25–75% and DLCO were decreased at rest. V˙O2, peak correlated with DLCO, TLC and IC at rest and with IC (r2=0.59; p<0.001) and decrease in IC (r2=0.44; p<0.001) at 90% of maximum workload. During exercise CHF patients do not exhibit EFL, but some of them develop DH that is associated with lower V˙O2, peak.

Diagnostic accuracy of metronome‐paced tachypnea to detect dynamic hyperinflation

This prospective study was carried out to investigate if metronome-paced tachypnea (MPT) can serve as an accurate diagnostic tool to identify patients with chronic obstructive pulmonary disease (COPD) who are susceptible to develop dynamic hyperinflation during exercise. Commonly, this is assessed by measuring change in inspiratory capacity (IC) during cardiopulmonary exercise testing (CPET), which, however, is complex and laborious. Fifty-three patients with COPD (FEV(1) 58 ± 22%pred) and 20 age-matched healthy subjects were characterized by lung function testing and performed CPET (reference standard) and MPT. The repeatability coefficient of IC (10·2%) was used as cut-off to classify subjects as hyperinflators during CPET. Subsequently, dynamic hyperinflation was measured after MPT. With receiver operating characteristic analysis, the optimal cut-off for MPT-induced dynamic hyperinflation was determined and sensitivity and specificity of MPT to identify hyperinflators were evaluated. With 10·2% decrease in IC as cut-off for CPET-induced dynamic hyperinflation, the optimal cut-off for MPT was 11·1% decrease in IC. Using these cut-offs, MPT had a sensitivity of 85% and specificity of 85% to identify the subjects who hyperinflated during CPET. The MPT test shows good overall accuracy to identify subjects who are susceptible to develop dynamic hyperinflation during CPET. Before considering the use of MPT as a screening tool for dynamic hyperinflation in COPD, sensitivity and specificity need further evaluation.

Effect of Bisoprolol on Respiratory Function and Exercise Capacity in Chronic Obstructive Pulmonary Disease

Cardioselective β blockers are considered to have little impact on lung function at rest in patients with chronic obstructive pulmonary disease (COPD). However, their effects on dynamic hyperinflation, an important mechanism contributing to symptoms and exercise tolerance in patients with COPD, have not been evaluated. Twenty-seven patients with moderate to severe COPD (forced expiratory volume in 1 second 52 ± 13% predicted) completed pulmonary function tests, echocardiography, maximal exercise tests, and cycle endurance tests at baseline. Inspiratory capacity was measured at 2-minute intervals during the cycle endurance test to quantify dynamic hyperinflation. Pulmonary function and cycle endurance testing were repeated after 14 days of bisoprolol 10 mg/day and 14 days of placebo in a randomized, double-blind, placebo-controlled, crossover trial. The extent of dynamic hyperinflation at peak isotime exercise with bisoprolol and placebo was compared. Peak isotime was defined as the latest time point that was reached during the 2 cycle endurance tests. Changes in inspiratory capacity from rest to peak isotime were different with bisoprolol compared to placebo (-0.50 ± 0.35 vs -0.41 ± 0.33 L, p = 0.01). Exercise duration tended to be lower with bisoprolol compared to placebo (305 ± 125 vs 353 ± 172 seconds, p = 0.11). The magnitude of change in exercise duration between the bisoprolol and placebo conditions was correlated with the magnitude of change in inspiratory capacity (r = 0.57, p <0.01). In conclusion, bisoprolol was associated with modest worsening dynamic hyperinflation, whereas exercise duration remained unchanged in patients with moderate to severe COPD. The magnitude of these effects was small and should not contraindicate the use of bisoprolol in patients with COPD.