Effects of bronchodilators on dynamic hyperinflation following hyperventilation in patients with COPD

Detection of dynamic lung hyperinflation using cardiopulmonary exercise testing and respiratory function in patients with stable cardiac disease: a multicenter, cross-sectional study

BACKGROUND

Many patients with heart disease potentially have comorbid chronic obstructive pulmonary disease (COPD); however, there are not enough opportunities for screening, and the qualitative differentiation of shortness of breath (SOB) has not been well established. We investigated the detection rate of SOB based on a visual and qualitative dynamic lung hyperinflation (DLH) detection index during cardiopulmonary exercise testing (CPET) and assessed potential differences in respiratory function between groups.

METHODS

We recruited 534 patients with heart disease or patients who underwent simultaneous CPET and spirometry (369 males, 67.0 ± 12.9 years) to scrutinize physical functions. The difference between inspiratory and expiratory tidal volume was calculated (TV E-I) from the breath-by-breath data. Patients were grouped into convex (decreased TV E-I) and non-convex (unchanged or increased TV E-I) groups based on their TV E-I values after the start of exercise.

RESULTS

Among the recruited patients, 129 (24.2%) were categorized in the convex group. There was no difference in clinical characteristics between the two groups. The Borg scale scores at the end of the CPET showed no difference. VE/VCO2 slope, its Y-intercept, and minimum VE/VCO2 showed no significant difference between the groups. In the convex group, FEV1.0/FVC was significantly lower compared to that in the non-convex group (69.4 ± 13.1 vs. 75.0 ± 9.0%). Moreover, significant correlations were observed between FEV1.0/FVC and Y-intercept (r=-0.343), as well as between the difference between minimum VE/VCO2 and VE/VCO2 slope (r=-0.478).

CONCLUSIONS

The convex group showed decreased respiratory function, suggesting a potential airway obstruction during exercise. A combined assessment of the TV E-I and Y-intercept of the VE/VCO2 slope or the difference between the minimum VE/VCO2 and VE/VCO2 slopes could potentially detect COPD or airway obstruction.

The concept of detection of dynamic lung hyperinflation using cardiopulmonary exercise testing

Dynamic lung hyperinflation (DLH) caused by air trapping, which increases residual air volume, is a common cause of shortness of breath on exertion in chronic obstructive pulmonary disease (COPD). DLH is commonly evaluated by measuring the decrease in maximal inspiratory volume during exercise, or using the hyperventilation method. However, only few facilities perform these methods, and testing opportunities are limited. Therefore, we investigated the possibility of visually and qualitatively detecting DLH using data from a cardiopulmonary exercise test (CPET). Four men who underwent symptom-limiting CPET were included in this study, including a male patient in his 60s with confirmed COPD, a 50s male long-term smoker, and 2 healthy men in their 20s and 70s, respectively. We calculated the difference between the inspiratory tidal volume (TV I) and expiratory tidal volume (TV E) per breath (TV E-I) from the breath-by-breath data of each CPET and plotted it against the time axis. No decrease in TV E-I was observed in either of the healthy men. However, in the patient with COPD and long-term smoker, TV E-I began to decrease immediately after the initiation of exercise. These results indicate that DLH can be visually detected using CPET data. However, this study was a validation of a limited number of cases, and a comparison with existing evaluation methods and verification of disease specificity are required.

Association between chronic obstructive pulmonary disease and ventricular arrhythmia: a nationwide population-based cohort study

The ventricular arrhythmia (VA)-chronic obstructive pulmonary disease (COPD) association and related risk factors remain unclear. Using 2001-2012 data from National Health Insurance Research Database, we retrospectively reviewed 71,838 patients diagnosed as having COPD and 71,838 age- and sex-matched controls. After adjustments for comorbidities, medication, urbanization level, and monthly income, patients with COPD had higher incidence rates of VA than did the controls (adjusted hazard ratio [aHR] [95% confidence interval (CI)]: 1.45 [1.25-1.68]). More hospitalization or emergency visits because of acute COPD exacerbation (aHRs [95% CIs] for first, second, and third visits: 1.28 [1.08-1.50], 1.75 [1.32-2.32], and 1.88 [1.46-2.41], respectively) and asthma-COPD overlap (aHR [95% CI]: 1.49 [1.25-1.79]) were associated with high VA risk in patients with COPD. In the multivariate analysis, heart failure (aHR [95% CI]: 2.37 [1.79-3.14]), diabetes (aHR [95% CI]:1.64 [1.29-2.08]), age ≥75 (aHR [95% CI]: 2.48 [1.68-3.67]), male (aHR [95% CI]: 1.69[1.34-2.12]), and class III antiarrhythmic drug use (aHR [95% CI]: 2.49 [1.88-3.28]) are the most significant risk factors of new onset of VA in patients with COPD.

Work of breathing during arm bracing in normal male subjects

Objective

Although chronic obstructive pulmonary disease patients get relief from their dyspnea by arm bracing, the mechanics of this effect are unknown. This study aimed to investigate the mechanisms by which arm bracing affects dyspnea by measuring the work of breathing (WOB) in the arm bracing posture.

Methods

Six normal male subjects were studied in two standing postures: erect and with their arms braced. For the arm bracing posture, the subjects leaned forward with their arms stretched and rested their hands on a platform. Respiratory frequency was set at 20 tidal breaths/min with the use of a metronome, and tidal volume was set at 1 L by observing the lung volume on a monitor. All the subjects randomly adopted the two postures, and a preset respiratory pattern was measured for 30 s in each posture. Lung volume and flow rate were measured using a hot-wire flowmeter. Esophageal pressure was measured using a 12-cm balloon catheter. The WOB was estimated using modified Campbell diagrams.

Results

Lung volume increased and inspiratory resistive WOB decreased, while inspiratory elastic WOB increased significantly with arm bracing compared with that of the erect posture (P < 0.05).

Conclusion

Arm bracing posture increases the chest wall expansion thereby increasing the end-expiratory lung volume and decreasing the inspiratory resistive WOB among healthy individuals.

The Relationship Between the "Adherence Starts with Knowledge-20" Questionnaire and Clinical Factors in Patients with COPD: A Multi-Center, Cross-Sectional Study

Purpose

Inhaler therapy is the mainstay of chronic obstructive pulmonary disease (COPD) management. Poor adherence causes disease exacerbation and affects patient mortality. Although the Adherence Starts with Knowledge-20 (ASK-20) questionnaire is a reliable tool for assessing medication adherence, the relationship between the ASK-20 and clinical factors in patients with COPD remains unknown. We investigated the relationship between the ASK-20 and clinical factors, and assessed real-world inhaler therapy use.

Patients and Methods

A multicenter, cross-sectional study of outpatients with COPD undergoing inhaler treatment who completed the ASK-20 questionnaire was performed. We investigated COPD-related health status using the COPD Assessment Test (CAT), psychological status using the Hospital Anxiety and Depression Scale (HADS-anxiety and HADS-depression), respiratory function, patient satisfaction levels, and real-world inhaler therapy use.

Results

Of the total 319 patients, 87% were male with a median age of 74 years. Most patients had mild or moderate COPD, according to Global Initiative for Chronic Obstructive Lung Disease stage. The total ASK-20 scores correlated significantly with the CAT, HADS-anxiety, and HADS-depression scores (r = 0.27, 0.33, and 0.29, respectively, p < 0.01). Multivariable analysis showed that CAT and HADS-anxiety scores had an independent and significant impact on the ASK-20 scores [β, standardized regression coefficient: 0.18 (95% CI, 0.03–0.35; p = 0.02), and 0.29 (95% CI, 0.17–0.42; p < 0.01), respectively]; however, the ASK-20 scores were not correlated with age, sex, body mass index, cohabitation, modified Medical Research Council Dyspnea Scale score, pulmonary function, disease duration, number of COPD exacerbations per year, comorbidities, inhaler numbers, nor inhaler components.

Conclusion

The ASK-20 scores in patients with COPD were significantly associated with CAT and HADS scores. In Japan, Respimat was prescribed to younger patients and patients with lower CAT scores. The ASK-20, a simple evaluation method, is useful for identifying clinical factors affecting adherence in patients with COPD.

Effect of pulmonary rehabilitation with assistive use of short-acting β2 agonist in COPD patients using long-acting bronchodilators

Background: Assistive use of short-acting β2 agonists (SABAs) reportedly improves exercise tolerance, activities of daily living, and health-related quality of life (HRQOL) in patients with chronic obstructive pulmonary disease (COPD). However, the effect of SABA on physical activity (PA) is unclear.Objective: This study aimed to determine whether assistive use of SABA increases PA and whether additional pulmonary rehabilitation (PR) can aid further improvement.Methods: Twelve outpatients with COPD and dyspnea during daily activities despite regular use of long-acting bronchodilators were enrolled. This study comprised a 2-week pre-intervention investigation, a 12-week investigation of SABA effects, and an 8-week investigation of the additional effects of PR. Assistive use of SABA was allowed up to 4 times per day after the pre-intervention period. PA was measured for 14 consecutive days using an accelerometer sensor. Dyspnea, exercise tolerance, and HRQOL were evaluated at entry, at 4 and 12 weeks after initiating SABA use, and after completing PR.Results: Assistive use of SABA improved breathlessness during daily activities and increased PA (p < .001). PA and HRQOL were also improved following PR (p < .001 and p = .013, respectively).Conclusions: Combined therapy of SABA and PR can increase PA and HRQOL in COPD patients.

Efficacy of tiotropium and olodaterol combination therapy on dynamic lung hyperinflation evaluated by hyperventilation in COPD: an open-label, comparative before and after treatment study

Background: Dynamic lung hyperinflation (DLH) following metronome-paced incremental hyperventilation (MPIH) was reported to be useful for assessment of pathophysiological impairment in patients with chronic obstructive pulmonary disease (COPD), and the effects of tiotropium and olodaterol on DLH following MPIH have not been reported.

Methods: Treatment consisted of administration of tiotropium/olodaterol 5/5 μg inhalation solution (2.5/2.5 μg per actuation) using a soft-mist inhaler once a day. We compared outcomes before and after 8 weeks of treatment. The primary outcome was defined as a decrease in inspiratory capacity (IC) from rest by MPIH, which is an index of DLH. The secondary outcomes were COPD assessment test (CAT), forced expiratory volume in 1 s (FEV₁), and 6-min walking distance (6MWD). In addition, we investigated whether there were correlations between changes with treatment in DLH and FEV₁, 6MWD, and dyspnea.

Results: Thirty-three of the 38 registered patients completed this study. Most of these 33 patients had mild to moderate COPD. Decreasing IC by MPIH was significantly reduced by treatment for 8 weeks, with a mean change of about −0.11 to −0.13 mL (P <0.05). In addition, CAT score, FEV₁, and 6MWD improved with treatment (P <0.05). There were no significant correlations between changes in DLH, FEV₁, 6MWD, or dyspnea with treatment.

Conclusions: The results of this study showed that the combination of tiotropium and olodaterol is effective for improvement of DLH following hyperventilation.

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Is the Metronome-Paced Tachypnea Test (MPT) Ready for Clinical Use? Accuracy of the MPT in a Prospective and Clinical Study

BACKGROUND

A simple technique to measure dynamic hyperinflation (DH) in patients with chronic obstructive pulmonary disease (COPD) is the metronome-paced tachypnea test (MPT). Earlier studies show conflicting results about the accuracy of the MPT compared to cardiopulmonary exercise testing (CPET).

OBJECTIVES

The focus was to investigate the diagnostic accuracy of MPT to detect DH in a prospective and clinical study.

METHODS

COPD patients were included; all underwent spirometry, CPET, and MPT. DH (ΔIC) was calculated as the difference in % between inspiratory capacity (IC) at the start and end of the test divided by IC at the start. A subject was identified as a hyperinflator, if ΔIC (% of ICrest) was smaller than -10.2 and -11.1% in CPET and MPT, respectively. With these values, sensitivity and specificity were calculated. Bland-Altman plots were made of ΔIC (% of ICrest).

RESULTS

In the prospective and clinical study, 107 and 48 patients were included, respectively. Sensitivity of the MPT was 85% in both studies. The specificities were 33 and 27%, respectively. In the prospective study, B = +2.6%, L = 30.6, and -25.6%. In the clinical study, B = +0.8%, L = 31.0, and -29.1%.

CONCLUSION

MPT seems to be a good replacement for CPET in group studies. The mean amount of DH was not different between CPET and MPT. On an individual level, MPT cannot be used to identify hyperinflators; it should be kept in mind that MPT overdiagnoses DH. The amount of DH should not be interchanged between CPET and MPT.

Combination of assist use of short-acting beta-2 agonists inhalation and guidance based on patient-specific restrictions in daily behavior: Impact on physical activity of Japanese patients with chronic obstructive pulmonary disease

BACKGROUND

Assist use of inhaled short-acting beta 2 agonists (SABAs) is reportedly effective for preventing shortness of breath on exertion in chronic obstructive pulmonary disease (COPD) patients. However, it is unclear what strategy would be useful for improving physical activity in such patients. The aim is to investigate the effects of assisted use of SABA (procaterol) on physical activity in Japanese COPD patients targeting patient-specific restrictions in daily behavior.

METHODS

Fourteen patients with stable COPD (age: 72.1±1.5, %FEV₁: 55.6±4.5%) were asked to inhale 20 μg of procaterol 15 minutes before patient-specific daily physical activity that had been identified as limited by a questionnaire and document their usage in a diary. Physical activity was measured using a triaxial accelerometer and the results were collected every month for 2 months. In the first month, a clinician assessed whether inhalation of SABA was appropriate based on a usage diary and coached patients to conduct adequate assist use of SABA for limited physical activity.

RESULTS

The strategy significantly improved the physical activity level, assessed using the values of the metabolic equivalents (METs) multiplied by physical activity endurance, at ≥3.0 METs (p<0.05), and physical activity endurance at ≥2.5 and ≥3.0 METs, (p<0.05, p<0.05, respectively). The degree of improvement of physical activity level was significantly positively correlated with the baseline %FVC and %FEV₁ (p<0.05, p<0.05, respectively).

CONCLUSIONS

Assist use of SABA targeting patient-specific restrictions, particularly when better lung function is still preserved, could be a useful approach for improving physical activity in patients with COPD.

Usefulness of a Newly Developed Spirometer to Measure Dynamic Lung Hyperinflation following Incremental Hyperventilation in Patients with Chronic Obstructive Pulmonary Disease

Objective This study was performed to determine the usefulness of a newly developed spirometer for the quantitative assessment of dynamic lung hyperinflation (DLH) following incremental hyperventilation in chronic obstructive pulmonary disease (COPD). Methods The subjects were 54 patients with COPD and 25 healthy volunteers. Each subject was asked to hyperventilate for 30 seconds with stepwise increments starting at the resting respiration rate and increasing to respiratory rates of 20, 30, and finally 40 breaths/min while using a newly developed spirometer. The relationship between the observed inspiratory capacity (IC) reduction following incremental hyperventilation as an index of DLH and spirometry or the 6-minute walking distance was examined. Results The IC did not decrease significantly from the resting IC, even when the respiratory rate was increased, in the healthy volunteer group. However, in the COPD patient group, the IC decreased with increases in the respiratory rate. Significant correlations were found between all IC parameters and the severity of COPD. A significant negative correlation was also found between the decreased IC and the 6-minute walking distance. Conclusion These findings suggest that the quantitative assessment of DLH following incremental hyperventilation using the newly developed spirometer may be useful for the assessment of pathophysiological impairment in patients with COPD.

Efficacy of tiotropium and indacaterol monotherapy and their combination on dynamic lung hyperinflation in COPD: a random open-label crossover study

BACKGROUND AND OBJECTIVE

The difference in efficacy of long-acting muscarinic antagonists (LAMAs) and long-acting β2-agonists (LABAs) for dynamic lung hyperinflation (DLH) in COPD is unclear. The purpose of this study was to elucidate the difference in efficacy of LAMA and LABA alone and the combination thereof for DLH.

SUBJECTS AND METHODS

Thirty stable patients were enrolled and randomly divided into two groups following baseline measurements. One group was treated with 5 μg tiotropium (Respimat inhaler) for 4 weeks following a 4-week treatment with 150 μg indacaterol, while the other group was treated with indacaterol for 4 weeks following a 4-week treatment with tiotropium. For both groups, these treatments were followed by a combination of the two drugs for 4 weeks. Pulmonary function tests, including DLH evaluated by metronome-paced incremental hyperventilation and exercise tolerance evaluated by the shuttle-walk test, were performed at the end of each treatment period.

RESULTS

In total, 23 patients completed this study. Both tiotropium and indacaterol alone significantly increased forced expiratory volume in 1 second, exercise tolerance, and improved health status. Tiotropium significantly improved DLH, but indacaterol did not. The combination therapy resulted in further improvements in lung function and exercise tolerance, but not in DLH.

CONCLUSION

The efficacy of tiotropium in inhibiting DLH following metronome-paced incremental hyperventilation may be superior to that of 150 μg indacaterol, although the effects on airflow obstruction were the same, and the combination therapy showed further improvement in airflow obstruction, but not in DLH.

A Modified Method for Examining the Walking Pattern and Pace of COPD Patients in a 6-min Walk Test Before and After the Inhalation of Procaterol

Objective The 6-min walk test (6MWT) is a simple test that is used to examine the exercise tolerance and outcomes in patients with chronic obstructive pulmonary disease (COPD). Although the 6MWT is useful for assessing exercise tolerance, it is difficult to evaluate time-dependent parameters such as the walking pattern. A modified 6MWT has been devised to assess the walking pattern by calculating the number of steps per second (NSPS). This study was performed to investigate walking pattern of COPD patients in the modified 6MWT before and after a single inhalation of the short-acting β₂-agonist procaterol. Methods Nine male COPD patients participated in this study. The 6MWT was performed before and after the inhalation of procaterol hydrochloride. A digital video recording of the 6MWT was made. After the 6MWT, the number of steps walked by the subject in each 5-s period was counted manually with a hand counter while viewing the walking test on the video monitor. Results After the inhalation of procaterol, the 6-min walking distance increased significantly in comparison to baseline (p<0.01). The mean NSPS was also significantly increased after the inhalation of procaterol in comparison to baseline (p<0.01). The walking pattern was displayed on a graph of time versus NSPS, and the walking pace was shown by a graph of time versus cumulative steps. Conclusion The analysis of the COPD patients' walking test performance and their walking pattern and pace in the 6MWT may help to evaluate the effects of drug treatment.

Associations between the distance covered in the incremental shuttle walk test and lung function and health status in patients with chronic obstructive pulmonary disease

BACKGROUND

Field walk tests such as the incremental shuttle walk test (ISWT) are simple tests for assessing the degree of disability in individuals with chronic obstructive pulmonary disease (COPD). In the present study, the correlations between exercise performance in the ISWT, lung function, and health status were examined in patients with COPD of varying severities.

METHODS

A retrospective examination of 277 COPD patients was performed using the ISWT and lung function tests along with assessment of health status using St. George׳s Respiratory Questionnaire (SGRQ). In addition, we assessed the correlations between the walking distance, lung function parameters, and SGRQ scores.

RESULTS

ISWT distances were poorly correlated with lung function parameters and SGRQ scores in mild COPD patients. In contrast, ISWT distances were significantly correlated with pulmonary function parameters, such as vital capacity (%predicted) and forced expiratory volume in one second, and SGRQ scores in moderate and severe COPD patients.

CONCLUSIONS

The ISWT is more independent of health status and pulmonary function in patients with mild COPD compared to moderate or severe cases. Therefore, the exercise capacity of patients with mild COPD should be estimated by the ISWT.

Determining the Role of Dynamic Hyperinflation in Patients with Severe Chronic Obstructive Pulmonary Disease

BACKGROUND

Dynamic hyperinflation due to increased respiratory frequency during exercise is associated with limitations in exercise capacity in patients with moderately severe chronic obstructive pulmonary disease (COPD).

OBJECTIVES

The present study assessed whether the manually paced tachypnea (MPT) test, sitting at rest, induces dynamic hyperinflation correlating with exercise capacity in patients with very severe COPD.

METHODS

Dynamic hyperinflation was induced by the MPT test, using a breathing frequency of 40/min for 1 min. Dynamic hyperinflation was defined as a 'change' in inspiratory capacity (IC) before and directly after the MPT test. At baseline, static hyperinflation by body plethysmography was measured, as well as the 6-min walking test and spirometry.

RESULTS

We studied 74 patients with severe COPD (age 59 ± 9 years, FEV1 28 ± 10% predicted). All patients tolerated the MPT test well. It induced a significant decrease in IC: -0.65 ± 0.33 liters, p < 0.001, correlating with the 6-min walking distance (rho = -0.246, p = 0.034). Static hyperinflation [IC/total lung capacity (TLC)] at baseline correlated stronger with the 6-min walking distance (r = 0.582, p < 0.001). Multiple regression analysis showed that IC/TLC, but not dynamic hyperinflation, was the only independent predictor of walking distance.

CONCLUSIONS

In patients with very severe COPD, dynamic hyperinflation measurement by the MPT test is feasible and contributes less importantly to exercise performance than static hyperinflation.

Regional chest wall volume changes during various breathing maneuvers in normal men

PURPOSE

The purpose of this study is to investigate the regional chest wall volume changes during various breathing maneuvers in normal men with an optical reflectance system (OR), which tracks reflective markers in three dimensions.

METHODS

Chest wall volume was measured by the OR system [VL(CW)], and lung volume was measured by hot wire spirometry [VL(SP)] in 15 healthy men during quiet breathing (QB), during breathing at a rate of 50 tidal breaths/min paced using a metronome (MT: metronome-paced tachypnea), and during a maximal forced inspiratory and expiratory maneuver (MFIE maneuver).

RESULTS

There were few discrepancies between VL(CW) and VL(SP) for QB and MT. In the MFIE maneuver, however VL(CW) was often underestimated compared with VL(SP), particularly during forced maximal expiration, because of pulmonary rib cage volume changes. Furthermore, the regional chest wall volume changes were affected by breathing maneuver alternation. In the pulmonary and abdominal rib cage, inspiratory reserve volume was larger than expiratory reserve volume, respectively, and in the abdomen, expiratory reserve volume was larger than inspiratory reserve volume.

CONCLUSION

Alternation of breathing maneuvers affects regional chest wall volume changes.

Pulmonary function impairment in patients with combined pulmonary fibrosis and emphysema with and without airflow obstruction

BACKGROUND

The syndrome of combined pulmonary fibrosis and emphysema (CPFE) is a recently described entity associating upper-lobe emphysema and lower-lobe fibrosis. We sought to evaluate differences in pulmonary function between CPFE patients with and without airflow obstruction.

SUBJECTS AND METHODS

Thirty-one CPFE patients were divided into two groups according to the presence or absence of irreversible airflow obstruction based on spirometry (forced expiratory volume in 1 second/forced vital capacity <70% following inhalation of a β2-agonist) as follows: CPFE patients with airflow obstruction (CPFE OB(+) group, n=11), and CPFE patients without airflow obstruction (CPFE OB(-) group, n=20). Pulmonary function, including respiratory impedance evaluated using impulse oscillometry and dynamic hyperinflation following metronome-paced incremental hyperventilation, was retrospectively analyzed in comparison with that observed in 49 chronic obstructive pulmonary disease (COPD) patients (n=49).

RESULTS

In imaging findings, low-attenuation-area scores on chest high-resolution computed tomography, representing the degree of emphysema, were significantly lower in the CPFE OB(-) group than in the CPFE OB(+) and COPD groups. In contrast, the severity of pulmonary fibrosis was greater in the CPFE OB(-) group than in the CPFE OB(+) group. In pulmonary function, lung hyperinflation was not apparent in the CPFE OB(-) group. Impairment of diffusion capacity was severe in both the CPFE OB(-) and CPFE OB(+) groups. Impulse oscillometry showed that respiratory resistance was not apparent in the CPFE OB(-) group compared with the COPD group, and that easy collapsibility of small airways during expiration of tidal breath was not apparent in the CPFE OB(+) group compared with the COPD group. Dynamic hyperinflation following metronome-paced incremental hyperventilation was significantly greater in the COPD group than in the CPFE OB(-) group, and also tended to be greater in the CPFE OB(+) group than in the CPFE OB(-) group.

CONCLUSION

The mechanisms underlying impairment of physiological function may differ among CPFE OB(+) patients, CPFE OB(-) patients, and COPD patients. CPFE is a heterogeneous disease, and may have distinct phenotypes physiologically and radiologically.

Comparing dynamic hyperinflation and associated dyspnea induced by metronome-paced tachypnea versus incremental exercise

Dynamic hyperinflation (DH) during exercise is associated with both dyspnea and exercise limitation in COPD. Metronome-paced tachypnoea (MPT) is a simple alternative for studying DH. We compared MPT with exercise testing (XT) as methods of provoking DH, and assessed their relationship with dyspnea. We studied 24 patients with moderate COPD (FEV1 59 ± 9% predicted) after inhalation of ipratropium/salbutamol combination or placebo in a double-blind, crossover design. Inspiratory capacity (IC) was measured at baseline and after 30 seconds of MPT with breathing frequencies (fR) of 20, 30 and 40 breaths/min and metronome-defined I:E ratios of 1:1 and 1:2, in random sequence, followed by incremental cycle ergometry with interval determinations of IC. DH was defined as a decline in IC from baseline (∆IC) for both methods. Dyspnea was assessed using a Borg CR-10 scale. ∆IC during MPT was greater with higher fR and I:E ratio of 1:1 versus 1:2, and less when patients were treated with bronchodilator rather than placebo (P = 0.032). DH occurred during 19 (40%) XTs, and during 35 (73%) tests using MPT. Eleven of 18 (61%) non-congruent XTs (where DH occurred on MPT but not XT) terminated before fR of 40 breaths/min was reached. Although greater during XT, the intensity of dyspnea bore no relationship to DH during either MPT and XT. MPT at 40 breaths/min and I:E of 1:1 elicits the greatest ∆IC, and is a more sensitive method for demonstrating DH. The relationship between DH and dyspnea is complex and not determined by DH alone.

Determinants of dynamic hyperinflation during metronome-paced tachypnea in COPD and normal subjects

In COPD, dynamic hyperinflation (DH) occurs during exercise and during metronome-paced tachypnea (MPT). We investigated the relationship of DH with breathing pattern and ventilation (V˙E) in COPD and normal subjects (NS). In 35 subjects with moderate COPD and 17 younger healthy volunteers we measured inspiratory capacity (IC), breathing frequency (fR), expiratory time (TE), ventilation (V˙E) and end-tidal carbon dioxide tension (PETCO2) at baseline and after 30s of MPT at 40breaths/min with metronome-defined I:E ratios of 1:1 and 1:2. A reduction in IC (ΔIC) was taken to indicate DH. In COPD subjects, DH correlated with TE but not with V˙E or PETCO2, and was best predicted by total lung capacity. NS also showed DH (although less than in COPD), which correlated with PETCO2 but not with fR, TE or V˙E. We conclude that MPT evokes DH in both NS and patients with COPD. TE is the most important determinant of DH during MPT in patients with COPD.

Additive efficacy of short-acting bronchodilators on dynamic hyperinflation and exercise tolerance in stable COPD patients treated with long-acting bronchodilators

The purpose of this study was to clarify the additive efficacy of short-acting β(2)-agonists (SABA) or muscarinic antagonists (SAMA) on dynamic hyperinflation and exercise tolerance in patients with chronic obstructive pulmonary disease (COPD) who had been treated with long-acting bronchodilators. Thirty-two patients with stable COPD who had been treated with long-acting bronchodilators, including long-acting muscarinic antagonists (LAMA), were examined by pulmonary function tests, dynamic hyperinflation evaluated by the method of step-wise metronome-paced incremental hyperventilation, and the incremental shuttle walking test before and after inhalation of SABA or SAMA. The additive efficacy of the two drugs was analyzed. Inhalation of SABA and SAMA improved airflow limitation and dynamic hyperinflation in stable COPD patients who had been treated with LAMA. Inhalation of SABA decreased respiratory resistance and the difference in respiratory resistance at 5 Hz and 20 Hz. On the whole, the additive efficacy of SABA on airflow limitation and dynamic hyperinflation was superior to that of SAMA. Furthermore, inhalation of SABA resulted in relief of breathlessness during exercise and significant improvement in exercise capacity. Inhalation of SABA resulted in significant improvement in exercise tolerance, which may have been due to improvement in dynamic hyperinflation. Single use of SABA before exercise, in addition to regular treatment with LAMA, may therefore be useful in stable COPD patients.

In Vivo Computed Tomography as a Research Tool to Investigate Asthma and COPD: Where Do We Stand?

Computed tomography (CT) is a clinical tool widely used to assess and followup asthma and chonic obstructive pulmonary disease (COPD) in humans. Strong efforts have been made the last decade to improve this technique as a quantitative research tool. Using semiautomatic softwares, quantification of airway wall thickness, lumen area, and bronchial wall density are available from large to intermediate conductive airways. Skeletonization of the bronchial tree can be built to assess its three-dimensional geometry. Lung parenchyma density can be analysed as a surrogate of small airway disease and emphysema. Since resident cells involve airway wall and lung parenchyma abnormalities, CT provides an accurate and reliable research tool to assess their role in vivo. This litterature review highlights the most recent advances made to assess asthma and COPD with CT, and also their drawbacks and the place of CT in clarifying the complex physiopathology of both diseases.

Comparison of efficacy of long-acting bronchodilators in emphysema dominant and emphysema nondominant chronic obstructive pulmonary disease

BACKGROUND

The purpose of this study was to clarify the association between morphological phenotypes according to the predominance of emphysema and efficacy of long-acting muscarinic antagonist and β(2) agonist bronchodilators in patients with chronic obstructive pulmonary disease (COPD).

METHODS

Seventy-two patients with stable COPD treated with tiotropium (n = 41) or salmeterol (n = 31) were evaluated for pulmonary function, dynamic hyperinflation following metronome-paced incremental hyperventilation, six-minute walking distance, and St George's Respiratory Questionnaire (SGRQ) before and 2-3 months following treatment with tiotropium or salmeterol. They were then visually divided into an emphysema dominant phenotype (n = 25 in the tiotropium-treated group and n = 22 in the salmeterol-treated group) and an emphysema nondominant phenotype on high-resolution computed tomography, and the efficacy of the two drugs in each phenotype was retrospectively analyzed.

RESULTS

Tiotropium significantly improved airflow limitation, oxygenation, and respiratory impedance in both the emphysema dominant and emphysema nondominant phenotypes, and improved dynamic hyperinflation, exercise capacity, and SGRQ in the emphysema dominant phenotype but not in the emphysema nondominant phenotype. Salmeterol significantly improved total score for SGRQ in the emphysema phenotype, but no significant effects on other parameters were found for either of the phenotypes.

CONCLUSION

These findings suggest that tiotropium is more effective than salmeterol for airflow limitation regardless of emphysema dominance, and also can improve dynamic hyperinflation in the emphysema dominant phenotype, which results in further improvement of exercise capacity and health-related quality of life.

Time course and degree of hyperinflation with metronome-paced tachypnea in COPD patients

In COPD patients, tachypnea should increase (dynamic) hyperinflation by shortening expiratory time. We developed a method to evaluate the time course and degree of dynamic hyperinflation during metronome-paced tachypnea. Fourteen patients with stable COPD (FEV(1) 43 +/- 13% predicted) were studied. Inspiratory capacity (IC) was measured breathing through a flow transducer. Subjects paced their respiratory rate (f(R)) at 20/min, 30/min and 40/min for 60-second periods in response to audible tones generated by a computer. IC measurements were obtained at baseline and after 30 and 60 seconds at each f(R). End-tidal carbon dioxide was monitored and f(R) was allowed to return to baseline between periods of tachypnea. Tachypnea produced reductions in IC of 200 +/- 240 ml, 380 +/- 330 ml and 540 +/- 300 ml after 30 seconds at 20/min, 30/min and 40/min, respectively. IC reduction at 60 seconds was similar to 30 seconds for each f(R). In patients with moderate-to-severe COPD, the dynamic hyperinflation induced by metronome-paced tachypnea was shown to occur rapidly and be complete by 30 seconds for a given f(R). Controlled increments in f(R) produced stepwise increases in dynamic hyperinflation. This standardized method could be a useful and easier method of assessing dynamic hyperinflation in COPD patients before and after therapeutic interventions.

Mechanisms of dyspnea in chronic lung disease

PURPOSE OF REVIEW

To discuss three emerging areas of research triggering new hypotheses for mechanisms of dyspnea.

RECENT FINDINGS

There has been an emphasis on the importance of lung volumes in evaluating symptoms and lung function in patients with chronic obstructive pulmonary disease. Dyspnea intensity seems to more closely correlate with measures of hyperinflation than airflow limitation, highlighting the importance of neuromechanical dissociation in the development of dyspnea. Inhaled furosemide has demonstrated a beneficial effect in laboratory-induced dyspnea, and the sensation of air hunger has been ameliorated by this therapy, possibly via activation of pulmonary stretch receptors. There appear to be distinct affective and sensory components of dyspnea, and the affective dimension may be modifiable, although this has not been fully studied.

SUMMARY

Dyspnea in chronic obstructive pulmonary disease is clearly related to hyperinflation, and lung volumes are valuable for characterizing disease. It remains unclear whether a limitation in tidal volume due to dynamic hyperinflation is the key factor in exertional dyspnea in this disease. Research of inhaled furosemide demonstrates the importance of afferent sensory input in modifying dyspnea, and deserves further study. The contributions of the affective and sensory components of dyspnea remain unclear, but should be studied further.