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

BACKGROUND AND OBJECTIVE: 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. METHODS: In this prospective bi-centre study from both Toulouse and Limoges Hospitals, we assessed DH during an incremental cycle ergometry before and 3 months 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, 6 minutes walking distance (6MWD), BODE and other dynamic measures like tele-expiratory volume (EELV) were also analysed. RESULTS: 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 Ë‚ 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. +2 mL; +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. CONCLUSIONS: DH decreases after EBVs treatment, and this improvement is correlated with static changes.

Association of air pollution exposure with exercise-induced oxygen desaturation in COPD.

BACKGROUND: There is a link between exposure to air pollution and the increased prevalence of chronic obstructive pulmonary disease (COPD) and declining pulmonary function, but the association with O2 desaturation during exercise in COPD patients with emphysema is unclear. Our aims were to estimate the prevalence of O2 desaturation during exercise in patients with COPD, and determine the association of exposure to air pollution with exercise-induced desaturation (EID), the degree of emphysema, and dynamic hyperinflation (DH). METHODS: We assessed the effects of 10-year prior to the HRCT assessment and 7 days prior to the six-minute walking test exposure to particulate matter with an aerodynamic diameter of < 10 µm (PM10) or of < 2.5 µM (PM2.5), nitrogen dioxide (NO2), and ozone (O3) in patients with emphysema in this retrospective cohort study. EID was defined as a nadir standard pulse oximetry (SpO2) level of < 90% or a delta (△)SpO2 level of ≥ 4%. Ambient air pollutant (PM2.5, PM10, O3, and NO2) data were obtained from Taiwan Environmental Protection Administration (EPA) air-monitoring stations, usually within 10 km to each participant's home address. RESULTS: We recruited 141 subjects with emphysema. 41.1% of patients with emphysema exhibited EID, and patients with EID had more dyspnea, worse lung function, more severe emphysema, more frequent acute exacerbations, managed a shorter walking distance, had DH, and greater long-term exposure to air pollution than those without EID. We observed that levels of 10-year concentrations of PM10, PM2.5, and NO2 were significantly associated with EID, PM10 and PM2.5 were associated with the severity of emphysema, and associated with DH in patients with emphysema. In contrast, short-term exposure did not have any effect on patients. CONCLUSION: Long-term exposure to ambient PM10, PM2.5 and NO2, but not O3, was associated with EID.

Sex differences in the ventilatory responses to exercise in mild to moderate obesity.

NEW FINDINGS: What is the central question of the study? What are the sex differences in ventilatory responses during exercise in adults with obesity? What is the main finding and its importance? Tidal volume and expiratory flows are lower in females when compared with males at higher levels of ventilation despite small increases in end-expiratory lung volumes. Since dyspnoea on exertion is a frequent complaint, particularly in females with obesity, careful attention should be paid to unpleasant respiratory symptoms and mechanical ventilatory constraints while prescribing exercise. ABSTRACT: Obesity is associated with altered ventilatory responses, which may be exacerbated in females due to the functional consequences of sex-related morphological differences in the respiratory system. This study examined sex differences in ventilatory responses during exercise in adults with obesity. Healthy adults with obesity (n = 73; 48 females) underwent pulmonary function testing, underwater weighing, magnetic resonance imaging (MRI), a graded exercise test to exhaustion, and two constant work rate exercise tests; one at a fixed work rate (60 W for females and 105 W for males) and one at a relative intensity (50% of peak oxygen uptake, V ̇ O 2 peak ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{peak}}}$ ). Metabolic, respiratory and perceptual responses were assessed during exercise. Compared with males, females used a smaller proportion of their ventilatory capacity at peak exercise (69.13 ± 14.49 vs. 77.41 ± 17.06% maximum voluntary ventilation, P = 0.0374). Females also utilized a smaller proportion of their forced vital capacity (FVC) at peak exercise (tidal volume: 48.51 ± 9.29 vs. 54.12 ± 10.43%FVC, P = 0.0218). End-expiratory lung volumes were 2-4% higher in females compared with males during exercise (P < 0.05), while end-inspiratory lung volumes were similar. Since the males were initiating inspiration from a lower lung volume, they experienced greater expiratory flow limitation during exercise. Ratings of perceived breathlessness during exercise were similar between females and males at comparable levels of ventilation. In summary, sex differences in the manifestations of obesity-related mechanical ventilatory constraints were observed. Since dyspnoea on exertion is a common complaint in patients with obesity, particularly in females, exercise prescriptions should be tailored with the goal of minimizing unpleasant respiratory sensations.

Evidence of ventilatory constraints during exercise in hypermobile Ehlers-Danlos syndrome.

PURPOSE: Hypermobile Ehlers-Danlos syndrome (hEDS) is a connective tissue disorder with many different symptoms such as pain, fatigue, dysautonomia, or respiratory symptoms. Among the respiratory manifestations described, the most frequent are exertional dyspnea and breathing difficulties. Mechanical ventilatory constraints during exercise could participate in these respiratory manifestations. The objective of this study was to explore the response of pulmonary flow-volume loops to exercise in patients with hEDS and to look for dynamic hyperinflation and expiratory flow limitation during exercise. METHODS: For this purpose, breathing pattern and tidal exercise flow-volume loops were recorded at two workloads (30% and 80% of the peak power output) of a constant load exercise test. RESULTS: Twelve patients were included (11 women, mean age 41 ± 14 years). The results showed a decrease (p = 0.028) in the inspiratory capacity (from 3.12 ± 0.49 L to 2.97 ± 0.52 L), an increase (p = 0.025) in the end-expiratory lung volume (from 0.73 ± 0.68 L to 0.88 ± 0.66 L, i.e., from EELV comprising 17 ± 12% to 21 ± 12% of forced vital capacity) between the two workloads in favor of dynamic hyperinflation, and half of the patients had expiratory flow limitations. CONCLUSION: This exploratory study provides evidence for mechanical ventilatory constraints during exercise in patients with hEDS, which may induce discomfort during exercise and could contribute to the respiratory symptomatology. TRIAL REGISTRATION NUMBER: This study is part of a larger clinical trial (ID: NCT04680793, December 2020).

Tidal volume expandability affected by flow, dynamic hyperinflation, and quasi-fixed inspiratory time in patients with COPD and healthy individuals.

Exertional dyspnea (ED) and impaired exercise performance (EP) are mainly caused by dynamic hyperinflation (DH) in chronic obstructive pulmonary disease (COPD) patients by constraining tidal volume expansion at peak exercise (VTpeak). As VTpeak is the product of inspiratory time (TIpeak) and flow (VT/TIpeak), it was hypothesized that VTpeak and VTpeak/total lung capacity (VTpeak/TLC) may be affected by TIpeak and VT/TIpeak. Hence, the study investigated the (1) effect of TIpeak and VT/TIpeak on VTpeak expansion, (2) factors associated with TIpeak, expiratory time (TEpeak), VT/TIpeak, and VTpeak/TLC, and (3) relationships between VT/TIpeak and VTpeak/TLC with ED and EP in COPD patients and controls. The study enrolled 126 male stable COPD patients and 33 sex-matched controls. At peak exercise, TIpeak was similar in all subjects (COPD versus controls, mean ± SD: 0.78 ± 0.17 s versus 0.81 ± 0.20 s, p = NS), whereas the COPD group had lower VT/TIpeak (1.71 ± 0.49 L/s versus 2.58 ± 0.69 L/s, p < .0001) and thus the COPD group had smaller VTpeak (1.31 ± 0.34 L versus 2.01 ± 0.45 L,p < .0001) and VTpeak/TLC (0.22 ± 0.06 vs 0.33 ± 0.05, p < .0001). TIpeak, TEpeak, and VT/TIpeak were mainly affected by exercise effort, whereas VTpeak/TLC was not. TEpeak, VT/TIpeak, and VTpeak/TLC were inversely changed by impaired lung function. TIpeak was not affected by lung function. Dynamic hyperinflation did not occur in the controls, however, VTpeak/TLC was strongly inversely related to DH (r = -0.79) and moderately to strongly related to lung function, ED, and EP in the COPD group. There was a slightly stronger correlation between VTpeak/TLC with ED and EP than VT/TIpeak in the COPD group (|r| = 0.55-0.56 vs 0.38-0.43). In summary, TIpeak was similar in both groups and the key to understanding how flow affects lung expansion. However, the DH volume effect was more important than the flow effect on ED and EP in the COPD group.

Comparison of Multiple Diagnostic Tests to Measure Dynamic Hyperinflation in Patients with Severe Emphysema Treated with Endobronchial Coils.

PURPOSE: For this study, we aimed to compare dynamic hyperinflation measured by cardiopulmonary exercise testing (CPET), a six-minute walking test (6-MWT), and a manually paced tachypnea test (MPT) in patients with severe emphysema who were treated with endobronchial coils. Additionally, we investigated whether dynamic hyperinflation changed after treatment with endobronchial coils. METHODS: Dynamic hyperinflation was measured with CPET, 6-MWT, and an MPT in 29 patients before and after coil treatment. RESULTS: There was no significant change in dynamic hyperinflation after treatment with coils. Comparison of CPET and MPT showed a strong association (rho 0.660, p < 0.001) and a moderate agreement (BA-plot, 202 ml difference in favor of MPT). There was only a moderate association of the 6-MWT with CPET (rho 0.361, p 0.024). CONCLUSION: MPT can be a suitable alternative to CPET to measure dynamic hyperinflation in severe emphysema but may overestimate dynamic hyperinflation possibly due to a higher breathing frequency.

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

BACKGROUND AND PURPOSE: In 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. METHODS: Dynamic 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). RESULTS: Eighteen 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). CONCLUSION: Bronchoscopic lung volume reduction increases the ability for dynamic hyperinflation in patients with severe emphysema. We propose this is a consequence of improved static hyperinflation.

The value of high-resolution computed tomography (HRCT) to determine exercise ventilatory inefficiency and dynamic hyperinflation in adult patients with cystic fibrosis.

INTRODUCTION: In Cystic Fibrosis (CF), exercise ventilatory inefficiency and dynamic hyperinflation (DH) cause exercise limitation and induce poor exercise tolerance. High-resolution computed tomography (HRCT) of the lung can detect pulmonary abnormalities in CF patients. We aimed to identify the determinants of exercise ventilatory inefficiency and DH using HRCT-derived metrics. METHODS: Fifty-two adult CF patients were prospectively enrolled; all participants underwent cardio-pulmonary exercise test (CPET) and HRCT. Radiological impairment was evaluated by the Brody II scoring system. Slope and intercept of the minute ventilation/CO2 production (V'E/V'CO2) regression line and the ratio of inspiratory capacity/total lung capacity (IC/TLC) at rest and at peak of exercise were measured. RESULTS: Four groups of patients were identified based on the combination of ventilatory efficiency (Vef) or inefficiency (Vin) and the presence/absence of DH. Compared to other groups, CF adults with Vin and DH had worse functional status and higher total (T), bronchiectasis (B) and air trapping (AT) scores at HRCT. Significant correlations were found between V'E/V'CO2 intercept and V'E/V'CO2 slope (ρ - 0.455, p = 0.001) and between V'E/V'CO2 intercept and Δ inspiratory capacity (IC) (ρ - 0.334, p = 0.015). Regression analysis identified AT score (cut-off 7.9, odds ratio-OR 3.50) as the only independent predictor of Vin and T (cut-off 53.6, OR 4.98), B (cut-off 16.1, OR 4.88), airways wall thickening (AWT) (cut-off 13, OR 3.41), and mucous plugging (MP) scores (cut-off 11.7, OR 4.18) as significant predictors of DH. CONCLUSION: In adult CF cohort, values of HRCT metrics are determinants of Vin (AT) and DH (T, B, AWT, MP).

Continuous monitoring of intrinsic PEEP based on expired CO2 kinetics: an experimental validation study.

BACKGROUND: Quantification of intrinsic PEEP (PEEPi) has important implications for patients subjected to invasive mechanical ventilation. A new non-invasive breath-by-breath method (etCO2D) for determination of PEEPi is evaluated. METHODS: In 12 mechanically ventilated pigs, dynamic hyperinflation was induced by interposing a resistance in the endotracheal tube. Airway pressure, flow, and exhaled CO2 were measured at the airway opening. Combining different I:E ratios, respiratory rates, and tidal volumes, 52 different levels of PEEPi (range 1.8-11.7 cmH2O; mean 8.45 ± 0.32 cmH2O) were studied. The etCO2D is based on the detection of the end-tidal dilution of the capnogram. This is measured at the airway opening by means of a CO2 sensor in which a 2-mm leak is added to the sensing chamber. This allows to detect a capnogram dilution with fresh air when the pressure coming from the ventilator exceeds the PEEPi. This method was compared with the occlusion method. RESULTS: The etCO2D method detected PEEPi step changes of 0.2 cmH2O. Reference and etCO2D PEEPi presented a good correlation (R2 0.80, P < 0.0001) and good agreement, bias - 0.26, and limits of agreement ± 1.96 SD (2.23, - 2.74) (P < 0.0001). CONCLUSIONS: The etCO2D method is a promising accurate simple way of continuously measure and monitor PEEPi. Its clinical validity needs, however, to be confirmed in clinical studies and in conditions with heterogeneous lung diseases.

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.

Hemodynamic effects of incremental lung hyperinflation.

Dynamic hyperinflation (DH) is common in chronic obstructive pulmonary disease and is associated with dyspnea and exercise intolerance. DH also has adverse cardiac effects, although the magnitude of DH and the mechanisms responsible for the hemodynamic impairment remain unclear. We hypothesized that incrementally increasing DH would systematically reduce left ventricular (LV) end-diastolic volume (LVEDV) and LV stroke volume (LVSV) because of direct ventricular interaction. Twenty-three healthy subjects (22 ± 2 yr) were exposed to varying degrees of expiratory loading to induce DH such that inspiratory capacity was decreased by 25%, 50%, 75%, and 100% (100% DH = inspiratory capacity of resting tidal volume plus inspiratory reserve volume ≈ 0.5 l). LV volumes, LV geometry, inferior vena cava collapsibility, and LV end-systolic wall stress were assessed by triplane echocardiography. 25% DH reduced LVEDV (-6 ± 5%) and LVSV (-9 ± 8%). 50% DH elicited a similar response in LVEDV (-6 ± 7%) and LVSV (-11 ± 10%) and was associated with significant septal flattening [31 ± 32% increase in the radius of septal curvature at end diastole (RSC-ED)]. 75% DH caused a larger reduction in LVEDV and LVSV (-9 ± 7% and -16 ± 10%, respectively) and RSC-ED (49 ± 70%). 100% DH caused the largest reduction in LVEDV and LVSV (-13 ± 9% and -18 ± 9%) and an increase in RSC-ED (56 ± 63%). Inferior vena cava collapsibility and LV afterload (LV end-systolic wall stress) were unchanged at all levels of DH. Modest DH (-0.6 ± 0.2 l inspiratory reserve volume) reduced LVSV because of reduced LVEDV, likely because of increased pulmonary vascular resistance. At higher levels of DH, direct ventricular interaction may be the primary cause of attenuated LVSV, as indicated by septal flattening because of a greater relative increase in right ventricular pressure and/or mediastinal constraint. NEW & NOTEWORTHY By systematically reducing inspiratory capacity during spontaneous breathing, we demonstrate that dynamic hyperinflation (DH) progressively reduces left ventricular (LV) end diastolic volume and LV stroke volume. Evidence of significant septal flattening suggests that direct ventricular interaction may be primarily responsible for the reduced LV stroke volume during DH. Hemodynamic impairment appears to occur at relatively lower levels of DH and may have important clinical implications for patients with chronic obstructive pulmonary disease.

Is daily physical activity affected by dynamic hyperinflation in adults with cystic fibrosis?

BACKGROUND: The aim of this study was to investigate the relationship between dynamic hyperinflation and daily physical activity (DPA) in adults with cystic fibrosis (CF). METHODS: Thirty-four clinically stable CF were studied. All patients undertook incremental cardiopulmonary exercise testing (CPET). CPET-related measurements included: oxygen uptake (V'O2), carbon dioxide production (V'CO2), ventilatory profile, work rate (W), inspiratory capacity (IC), end-expiratory lung volume (EELV). PA was assessed using the accelerometer SenseWear Pro3 Armband. RESULTS: Exercise tolerance was reduced in most of patients and the mean V'O2,peak value was 75.2% of predicted (28.5 ± 4.8 ml/min/kg). Seventy % of patients responded to CPET with dynamic hyperinflation. Higher incidence of dynamic hyperinflation was found in CF males compared to CF females (p = 0.026). Patients who developed dynamic hyperinflation during CPET had higher vigorous PA (p = 0.01) and more total energy expenditure (p = 0.006) than patients who did not. EELVΔ was related to activities requiring vigorous intensity and total energy expenditure (R = 0.46, p = 0.001; R = 0.57, p <  0.001). CONCLUSIONS: In adults with CF and mild to moderate lung impairment, DPA might not be limited by dynamic hyperinflation.

Effects of Pressure Support Ventilation May Be Lost at High Exercise Intensities in People with COPD.

Pressure support ventilation (PSV) may be used for exercise training in chronic obstructive pulmonary disease (COPD), but its acute effect on maximum exercise capacity is not fully known. The objective of this study was to evaluate the effect of 10 cm H2O PSV and a fixed PSV level titrated to patient comfort at rest on maximum exercise workload (WLmax), breathing pattern and metabolic parameters during a symptom-limited incremental bicycle test in individuals with COPD. Eleven individuals with COPD (forced expiratory volume in one second: 49 ± 16%; age: 64 ± 7 years) performed three exercise tests: without a ventilator, with 10 cm H2O of PSV and with a fixed level titrated to comfort at rest, using a SERVO-i ventilator. Tests were performed in randomized order and at least 48 hours apart. The WLmax, breathing pattern, metabolic parameters, and mouth pressure (Pmo) were compared using repeated measures analysis of variance. Mean PSV during titration was 8.2 ± 4.5 cm H2O. There was no difference in the WLmax achieved during the three tests. At rest, PSV increased the tidal volume, minute ventilation, and mean inspiratory flow with a lower end-tidal CO2; this was not sustained at peak exercise. Pmo decreased progressively (decreased unloading) with PSV at workloads close to peak, suggesting the ventilator was unable to keep up with the increased ventilatory demand at high workloads. In conclusion, with a Servo-i ventilator, 10 cm H2O of PSV and a fixed level of PSV established by titration to comfort at rest, is ineffective for the purpose of achieving higher exercise workloads as the acute physiological effects may not be sustained at peak exercise.

Typical patterns of expiratory flow and carbon dioxide in mechanically ventilated patients with spontaneous breathing.

Incomplete expiration of tidal volume can lead to dynamic hyperinflation and auto-PEEP. Methods are available for assessing these, but are not appropriate for patients with respiratory muscle activity, as occurs in pressure support. Information may exist in expiratory flow and carbon dioxide measurements, which, when taken together, may help characterize dynamic hyperinflation. This paper postulates such patterns and investigates whether these can be seen systematically in data. Two variables are proposed summarizing the number of incomplete expirations quantified as a lack of return to zero flow in expiration (IncExp), and the end tidal CO2 variability (varETCO2), over 20 breaths. Using these variables, three patterns of ventilation are postulated: (a) few incomplete expirations (IncExp < 2) and small varETCO2; (b) a variable number of incomplete expirations (2 ≤ IncExp ≤ 18) and large varETCO2; and (c) a large number of incomplete expirations (IncExp > 18) and small varETCO2. IncExp and varETCO2 were calculated from data describing respiratory flow and CO2 signals in 11 patients mechanically ventilated at 5 levels of pressure support. Data analysis showed that the three patterns presented systematically in the data, with periods of IncExp < 2 or IncExp > 18 having significantly lower variability in end-tidal CO2 than periods with 2 ≤ IncExp ≤ 18 (p < 0.05). It was also shown that sudden change in IncExp from either IncExp < 2 or IncExp > 18 to 2 ≤ IncExp ≤ 18 results in significant, rapid, change in the variability of end-tidal CO2 p < 0.05. This study illustrates that systematic patterns of expiratory flow and end-tidal CO2 are present in patients in supported mechanical ventilation, and that changes between these patterns can be identified. Further studies are required to see if these patterns characterize dynamic hyperinflation. If so, then their combination may provide a useful addition to understanding the patient at the bedside.

Heart-lung interaction in a model of COPD: importance of lung volume and direct ventricular interaction.

Chronic obstructive pulmonary disease (COPD) is associated with dynamic lung hyperinflation (DH), increased pulmonary vascular resistance (PVR), and large increases in negative intrathoracic pressure (nITP). The individual and interactive effect of these stressors on left ventricular (LV) filling, emptying, and geometry and the role of direct ventricular interaction (DVI) in mediating these interactions have not been fully elucidated. Twenty healthy subjects were exposed to the following stressors alone and in combination: 1) inspiratory resistive loading of -20 cmH2O (nITP), 2) expiratory resistive loading to cause dynamic hyperinflation (DH), and 3) normobaric-hypoxia to increase PVR (hPVR). LV volumes and geometry were assessed using triplane echocardiography. LV stroke volume (LVSV) was reduced during nITP by 7 ± 7% (mean ± SD; P < 0.001) through a 4 ± 5% reduction in LV end-diastolic volume (LVEDV) (P = 0.002), while DH reduced LVSV by 12 ± 13% (P = 0.001) due to a 9 ± 10% reduction in LVEDV (P < 0.001). The combination of nITP and DH (nITP+DH) caused larger reductions in LVSV (16 ± 16%, P < 0.001) and LVEDV (12 ± 10%, P < 0.001) than nITP alone (P < 0.05). The addition of hPVR to nITP+DH did not further reduce LV volumes. Significant septal flattening (indicating DVI) occurred in all conditions, with a significantly greater leftward septal shift occurring with nITP+DH than either condition alone (P < 0.05). In summary, the interaction of nITP and DH reduces LV filling through DVI. However, DH may be more detrimental to LV hemodynamics than nITP, likely due to mediastinal constraint of the heart amplifying DVI.

Chronic bronchitis leads to accelerated hyperinflation in COPD patients during exercise.

BACKGROUND AND OBJECTIVE: It is not known whether patients with chronic obstructive pulmonary disease (COPD) have a different exercise capacity with (CB(+) ) or without accompanying chronic bronchitis (CB(-) ). METHODS: We conducted spirometry, a 6-min walk distance test and cardiopulmonary exercise test in 50 age-matched healthy control subjects, 45 COPD patients without CB (CB(-) ) and 37 COPD patients with CB (CB(+) ). A multiple regression model was established to identify factors independently associated with peak oxygen consumption ( V ˙ O 2 ). RESULTS: Patients with and without CB had similar forced expiratory volume in 1 s (FEV1 ). CB(+) patients had a lower V ˙ O 2 . CB(+) and CB(-) participants had similar increases in tidal volume at peak exercise; however, CB(+) patients had an increased respiratory rate (RR). These patients reached the peak value for ratio of end-expiratory lung volume to total lung capacity (TLC) at a lower work load. A stepwise multiple linear regression analysis identified chronic bronchitis, FEV1 , diffusing capacity for carbon monoxide, the ratio of residual volume to TLC and serum tumour necrosis factor-α as independent predictors of peak V ˙ O 2 . CONCLUSIONS: CB significantly lowers exercise capacity in COPD patients because of dynamic hyperinflation during exercise. The accelerated dynamic hyperinflation may contribute to increased airway and systemic inflammation in COPD patients.

Air Current Applied to the Face Improves Exercise Performance in Patients with COPD.

PURPOSE: Improving dyspnea and exercise performance are goals of COPD therapy. We tested the hypothesis that air current applied to the face would lessen dyspnea and improve exercise performance in moderate-severe COPD patients. METHODS: We recruited 10 COPD patients (5 men, age 62 ± 6 years, FEV1 0.93 ± 0.11 L (34 ± 3% predicted), TLC 107 ± 6%, RV 172 ± 18%) naïve to the study hypothesis. Each patient was randomized in a crossover fashion to lower extremity ergometry at constant submaximal workload with a 12-diameter fan directed at the patients face or exposed leg. Each patients' studies were separated by at least 1 week. Inspiratory capacity and Borg dyspnea score were measured every 2 min and at maximal exercise. RESULTS: Total exercise time was longer when the fan was directed to the face (14.3 ± 12 vs. 9.4 ± 7.6 min, face vs. leg, respectively, p = 0.03). Inspiratory capacity tended to be greater with the fan directed to the face (1.4 (0.6-3.25) vs. 1.26 (0.56-2.89) L, p = 0.06). There was a reduction in dynamic hyperinflation, as reflected by higher IRV area in the fan on face group (553 ± 562 a.u. vs. 328 ± 319 a.u., p = 0.047). There was a significant improvement in the Borg dyspnea score at maximal exercise (5.0 (0-10) vs. 6.5 (0-10), p = 0.03), despite exercising for 34 % longer with the fan directed to the face. CONCLUSIONS: Air current applied to the face improves exercise performance in COPD. Possible mechanisms include an alteration in breathing pattern that diminishes development of dynamic hyperinflation or to a change in perception of breathlessness.

Reading pulmonary vascular pressure tracings. How to handle the problems of zero leveling and respiratory swings.

The accuracy of pulmonary vascular pressure measurements is of great diagnostic and prognostic relevance. However, there is variability of zero leveling procedures, and the current recommendation of end-expiratory reading may not always be adequate. A review of physiological and anatomical data, supported by recent imaging, leads to the practical recommendation of zero leveling at the cross-section of three transthoracic planes, which are, respectively midchest frontal, transverse through the fourth intercostal space, and midsagittal. As for the inevitable respiratory pressure swings, end-expiratory reading at functional residual capacity allows for minimal influence of elastic lung recoil on pulmonary pressure reading. However, hyperventilation is associated with changes in end-expiratory lung volume and increased intrathoracic pressure, eventually exacerbated by expiratory muscle contraction and dynamic hyperinflation, all increasing pulmonary vascular pressures. This problem is amplified in patients with obstructed airways. With the exception of dynamic hyperinflation states, it is reasonable to assume that negative inspiratory and positive expiratory intrathoracic pressures cancel each other out, so averaging pulmonary vascular pressures over several respiratory cycles is most often preferable. This recommendation may be generalized for the purpose of consistency and makes sense, as pulmonary blood flow measurements are not corrected for phasic inspiratory and expiratory changes in clinical practice.

The Impact of Homogeneous Versus Heterogeneous Emphysema on Dynamic Hyperinflation in Patients With Severe COPD Assessed for Lung Volume Reduction.

Dynamic hyperinflation (DH) is a pathophysiologic hallmark of Chronic Obstructive Pulmonary Disease (COPD). The aim of this study was to investigate the impact of emphysema distribution on DH during a maximal cardiopulmonary exercise test (CPET) in patients with severe COPD. This was a retrospective analysis of prospectively collected data among severe COPD patients who underwent thoracic high-resolution computed tomography, full lung function measurements and maximal CPET with inspiratory manouvers as assessment for a lung volume reduction procedure. ΔIC was calculated by subtracting the end-exercise inspiratory capacity (eIC) from resting IC (rIC) and expressed as a percentage of rIC (ΔIC%). Emphysema quantification was conducted at 3 predefined levels using the syngo PULMO-CT (Siemens AG); a difference >25% between best and worse slice was defined as heterogeneous emphysema. Fifty patients with heterogeneous (62.7% male; 60.9 ± 7.5 years old; FEV1% = 32.4 ± 11.4) and 14 with homogeneous emphysema (61.5% male; 62.5 ± 5.9 years old; FEV1% = 28.1 ± 10.3) fulfilled the enrolment criteria. The groups were matched for all baseline variables. ΔIC% was significantly higher in homogeneous emphysema (39.8% ± 9.8% vs.31.2% ± 13%, p = 0.031), while no other CPET parameter differed between the groups. Upper lobe predominance of emphysema correlated positively with peak oxygen pulse, peak oxygen uptake and peak respiratory rate, and negatively with ΔIC%. Homogeneous emphysema is associated with more DH during maximum exercise in COPD patients.