Alveolar-capillary membrane dysfunction in heart failure: evidence of a pathophysiologic role

Neural respiratory drive during maximal voluntary ventilation in individuals with hypertension: A case-control study

Neural respiratory drive (NRD) is measured using a non-invasive recording of respiratory electromyographic signal. The parasternal intercostal muscle can assess the imbalance between the load and capacity of respiratory muscles and presents a similar pattern to diaphragmatic activity. We aimed to analyze the neural respiratory drive in seventeen individuals with hypertension during quite breathing and maximal voluntary ventilation (MVV) (103.9 ± 5.89 vs. 122.6 ± 5 l/min) in comparison with seventeen healthy subjects (46.5 ± 2.5 vs. 46.4 ± 2.4 years), respectively. The study protocol was composed of quite breathing during five minutes, maximum inspiratory pressure followed by maximal ventilatory ventilation (MVV) was recorded once for 15 seconds. Anthropometric measurements were collected, weight, height, waist, hip, and calf circumferences, waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), BMI, and conicity index (CI). Differences between groups were analyzed using the unpaired t-test or Mann-Whitney test to determine the difference between groups and moments. A significance level of 5% (p<0,05) was adopted for all statistical analyses. The group of individuals with hypertension presented higher values when compared to the healthy group for neural respiratory drive (EMGpara% 17.9±1.3 vs. 13.1±0.8, p = 0.0006) and neural respiratory drive index (NRDi (AU) 320±25 vs. 205.7±15,p = 0.0004) during quiet breathing and maximal ventilatory ventilation (EMGpara% 29.3±2.7 vs. 18.3±0.8, p = 0.000, NRDi (AU) 3140±259.4 vs. 1886±73.1,p<0.0001), respectively. In conclusion, individuals with hypertension presented higher NRD during quiet breathing and maximal ventilatory ventilation when compared to healthy individuals.

Cardiopulmonary Exercise Testing in Evaluating Transthyretin Amyloidosis

Importance

Cardiopulmonary exercise testing (CPET) has an established role in the assessment of patients with heart failure. However, data are lacking in patients with transthyretin (ATTR) amyloidosis.

Objective

To use CPET to characterize the spectrum of functional phenotypes in patients with ATTR amyloidosis and assess their association with the cardiac amyloid burden as well as the association between CPET parameters and prognosis.

Design, Setting and Participants

This single-center study evaluated patients diagnosed with ATTR amyloidosis from May 2019 to September 2022 who underwent CPET at the National Amyloidosis Centre. Of 1045 patients approached, 506 were included and completed the study. Patients were excluded if they had an absolute contraindication to CPET or declined participation. The mean (SD) follow-up period was 22.4 (11.6) months.

Main Outcomes and Measures

Comparison of CPET parameters across disease phenotypes (ATTR with cardiomyopathy [ATTR-CM], polyneuropathy, or both [ATTR-mixed]), differences in CPET parameters based on degree of amyloid infiltration (as measured by cardiovascular magnetic resonance [CMR] with extracellular volume mapping), and association between CPET parameters and prognosis.

Results

Among the 506 patients with ATTR amyloidosis included in this study, the mean (SD) age was 73.5 (10.2) years, and 457 participants (90.3%) were male. Impairment in functional capacity was highly prevalent. Functional impairment in ATTR-CM and ATTR-mixed phenotypes (peak mean [SD] oxygen consumption [VO2], 14.5 [4.3] mL/kg/min and 15.7 [6.2] mL/kg/min, respectively) was observed alongside impairment in the oxygen pulse, with ventilatory efficiency highest in ATTR-CM (mean [SD] ventilatory efficiency/volume of carbon dioxide expired slope, 38.1 [8.6]). Chronotropic incompetence and exercise oscillatory ventilation (EOV) were highly prevalent across all phenotypes, with both the prevalence and severity being higher than in heart failure from different etiologies. Worsening of amyloid burden on CMR was associated with decline in multiple CPET parameters, although chronotropic response and EOV remained abnormal irrespective of amyloid burden. On multivariable Cox regression analysis, peak VO2 and peak systolic blood pressure (SBP) were independently associated with prognosis (peak VO2: hazard ratio, 0.89 [95% CI, 0.81-0.99; P = .03]; peak SBP: hazard ratio, 0.98 [95% CI, 0.97-0.99; P < .001]).

Conclusions and Relevance

In this study, ATTR amyloidosis was characterized by distinct patterns of functional impairment between all disease phenotypes. A high prevalence of chronotropic incompetence, EOV, and ventilatory inefficiency were characteristic of this population. CPET parameters were associated with amyloid burden by CMR and with peak VO2, and SBP, which have been shown to be independent predictors of mortality. These findings suggest that CPET may be useful in characterizing distinct patterns of functional impairment across the spectrum of amyloid infiltration and predicting outcomes, and potentially offers a more comprehensive method of evaluating functional capacity for future prospective studies.

Diffusing Capacity as a Predictor of Hospitalizations in a Clinical Cohort of Chronic Obstructive Pulmonary Disease

Rationale: Chronic obstructive pulmonary disease (COPD) hospitalizations are a major burden on patients. Diffusing capacity of the lung for carbon monoxide (DlCO) is a potential predictor that has not been studied in large cohorts. Objectives: This study used electronic health record data to evaluate whether clinically obtained DlCO predicts COPD hospitalizations. Methods: We performed time-to-event analyses of individuals with COPD and DlCO measurements from the Johns Hopkins COPD Precision Medicine Center of Excellence. Cox proportional hazard methods were used to model time from DlCO measurement to first COPD hospitalization and composite first hospitalization or death, adjusting for age, sex, race, body mass index, smoking status, forced expiratory volume in 1 second (FEV1), history of prior COPD hospitalization, and comorbidities. To identify the utility of including DlCO in risk models, area under the receiver operating curve (AUC) values were calculated for models with and without DlCO. Results were externally validated in a separate analogous cohort. Results: Of 2,793 participants, 368 (13%) had a COPD hospitalization within 3 years. In adjusted analyses, for every 10% decrease in DlCO% predicted, risk of COPD hospitalization increased by 10% (hazard ratio, 1.1; 95% confidence interval, 1.1-1.2; P < 0.001). Similar associations were observed for COPD hospitalizations or death. The model including demographics, comorbidities, FEV1, DlCO, and prior COPD hospitalizations performed well, with an AUC of 0.85 and an AUC of 0.84 in an external validation cohort. Conclusions: Diffusing capacity is a strong predictor of COPD hospitalizations in a clinical cohort of individuals with COPD, independent of airflow obstruction and prior hospitalizations. These findings support incorporation of DlCO in risk assessment of patients with COPD.

Diabetic Pneumopathy- A Novel Diabetes-associated Complication: Pathophysiology, the Underlying Mechanism and Combination Medication

BACKGROUND

The "diabetic lung" has been identified as a possible target organ in diabetes, with abnormalities in ventilation control, bronchomotor tone, lung volume, pulmonary diffusing capacity, and neuroadrenergic bronchial innervation.

OBJECTIVE

This review summarizes studies related to diabetic pneumopathy, pathophysiology and a number of pulmonary disorders including type 1 and type 2 diabetes.

METHODS

Electronic searches were conducted on databases such as Pub Med, Wiley Online Library (WOL), Scopus, Elsevier, ScienceDirect, and Google Scholar using standard keywords "diabetes," "diabetes Pneumopathy," "Pathophysiology," "Lung diseases," "lung infection" for review articles published between 1978 to 2023 very few previous review articles based their focus on diabetic pneumopathy and its pathophysiology.

RESULTS

Globally, the incidence of diabetes mellitus has been rising. It is a chronic, progressive metabolic disease. The "diabetic lung" may serve as a model of accelerated ageing since diabetics' rate of respiratory function deterioration is two to three-times higher than that of normal, non-smoking people.

CONCLUSION

Diabetes-induced pulmonary dysfunction has not gained the attention it deserves due to a lack of proven causality and changes in cellular properties. The mechanism underlying a particular lung illness can still only be partially activated by diabetes but there is evidence that hyperglycemia is linked to pulmonary fibrosis in diabetic people.

The alveolar-capillary unit in the physiopathological conditions of heart failure: identification of a potential marker

In this review, we describe the structure and function of the alveolar-capillary membrane and the identification of a novel potential marker of its integrity in the context of heart failure (HF). The alveolar-capillary membrane is indeed a crucial structure for the maintenance of the lung parenchyma gas exchange capacity, and the occurrence of pathological conditions determining lung fluids accumulation, such as HF, might significantly impair lung diffusion capacity altering the alveolar-capillary membrane protective functions. In the years, we found that the presence of immature forms of the surfactant protein-type B (proSP-B) in the circulation reflects alterations in the alveolar-capillary membrane integrity. We discussed our main achievements showing that proSP-B, due to its chemical properties, specifically binds to high-density lipoprotein, impairing their antioxidant activity, and likely contributing to the progression of the disease. Further, we found that immature proSP-B, not the mature protein, is related to lung abnormalities, more precisely than the lung function parameters. Thus, to the list of the potential proposed markers of HF, we add proSP-B, which represents a precise marker of alveolar-capillary membrane dysfunction in HF, correlates with prognosis, and represents a precocious marker of drug therapy.

Association between spirometry pattern, left ventricular diastolic function, and mortality

BACKGROUND

Spirometric abnormalities have been related to incident heart failure in general population, who generally have preserved left ventricular ejection fraction (LVEF). We aimed to investigate the association between spirometric indices, cardiac functions and clinical outcomes.

METHODS

Subjects presenting with exertional dyspnoea and received spirometry and echocardiography were eligible for this study. Forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1)/FVC ratio were measured to define the spirometry patterns: normal (FEV1/FVC ≥ 70%, FVC ≥ 80%), obstructive (FEV1/FVC < 70%, FVC ≥ 80%), restrictive pattern (FEV1/FVC ≥ 70%, FVC < 80%) and mixed (FEV1/FVC < 70%, FVC < 80%). The diastolic dysfunction index (DDi) was the counts of the indicators, including septal e' velocity <7 cm/s, septal E/e' > 15, pulmonary artery systolic pressure > 35 mmHg and left atrial dimension >40 mm.

RESULTS

Among a total of 8669 participants (65.8 ± 16.3 years, 56% men), 3739 (43.1%), 829 (9.6%), 3050 (35.2%) and 1051 (12.1%) had normal, obstructive, restrictive and mixed spirometry pattern, respectively. Subjects with restrictive or mixed spirometry pattern had higher DDi and worse long-term survival than those with obstructive or normal ventilation. FVC but not FEV1/FVC was predictive of 5-year mortality, independent of age, sex, renal function, LVEF, DDi, body mass index, and comorbidities (hazard ratio, 95% confidence intervals: .981, .977-.985). Furthermore, there was an inverse nonlinear relationship between FVC and DDi, suggesting the declined FVC may mediate 43% of the prognostic hazard of left ventricular diastolic dysfunction.

CONCLUSIONS

The restrictive spirometry pattern or the declined FVC was associated with left ventricular diastolic dysfunction, which aggravated the long-term mortality in the ambulatory dyspnoeic subjects.

Biomechanical and Mechanobiological Drivers of the Transition From PostCapillary Pulmonary Hypertension to Combined Pre-/PostCapillary Pulmonary Hypertension

Combined pre-/postcapillary pulmonary hypertension (Cpc-PH), a complication of left heart failure, is associated with higher mortality rates than isolated postcapillary pulmonary hypertension alone. Currently, knowledge gaps persist on the mechanisms responsible for the progression of isolated postcapillary pulmonary hypertension (Ipc-PH) to Cpc-PH. Here, we review the biomechanical and mechanobiological impact of left heart failure on pulmonary circulation, including mechanotransduction of these pathological forces, which lead to altered biological signaling and detrimental remodeling, driving the progression to Cpc-PH. We focus on pathologically increased cyclic stretch and decreased wall shear stress; mechanotransduction by endothelial cells, smooth muscle cells, and pulmonary arterial fibroblasts; and signaling-stimulated remodeling of the pulmonary veins, capillaries, and arteries that propel the transition from Ipc-PH to Cpc-PH. Identifying biomechanical and mechanobiological mechanisms of Cpc-PH progression may highlight potential pharmacologic avenues to prevent right heart failure and subsequent mortality.

Pulmonary Oxygen Exchange in a Rhythmically Expanding–Contracting Alveolus–Capillary Model

Pulmonary gas exchanges are vital to human health, and disruptions to this process have been associated with many respiratory diseases. Previous gas exchange studies have predominately relied on whole-body testing and theoretical analysis with 1D or static models. However, pulmonary gas exchanges are inherently a dynamic process in 3D spaces with instantaneous interactions between air, blood, and tissue. This study aimed to develop a computational model for oxygen exchange that considered all factors mentioned above. Therefore, an integrated alveolus–membrane–capillary geometry was developed with prescribed rhythmic expansion/contraction. Airflow ventilation, blood perfusion, and oxygen diffusion were simulated using COMSOL. The temporal and spatial distribution of blood flow and oxygen within the capillaries were simulated under varying breathing depths and cardiac outputs. The results showed highly nonuniform blood flow distributions in the capillary network, while the rhythmic oscillation further increased this nonuniformity, leading to stagnant blood flow in the distal vessels. A static alveolus–capillary geometry underestimated perfusion by 11% for normal respirations, and the deviation grew with breathing depth. The rhythmic motion caused a phase lag in the blood flow. The blood PO2 reached equilibrium with the alveolar air after traveling 1/5–1/3 of the capillary network. The time to reach this equilibrium was significantly influenced by the air–blood barrier diffusivity, while it was only slightly affected by the perfusion rate. The computational platform in this study could be instrumental in obtaining refined knowledge of pulmonary O2 exchanges.

Capillary communication: the role of capillaries in sensing the tissue environment, coordinating the microvascular, and controlling blood flow

Historically, capillaries have been viewed as the microvascular site for flux of nutrients to cells and removal of waste products. Capillaries are the most numerous blood vessel segment within the tissue, whose vascular wall consists of only a single layer of endothelial cells and are situated within microns of each cell of the tissue, all of which optimizes capillaries for the exchange of nutrients between the blood compartment and the interstitial space of tissues. There is, however, a growing body of evidence to support that capillaries play an important role in sensing the tissue environment, coordinating microvascular network responses, and controlling blood flow. Much of our growing understanding of capillaries stems from work in skeletal muscle and more recent work in the brain, where capillaries can be stimulated by products released from cells of the tissue during increased activity and are able to communicate with upstream and downstream vascular segments, enabling capillaries to sense the activity levels of the tissue and send signals to the microvascular network to coordinate the blood flow response. This review will focus on the emerging role that capillaries play in communication between cells of the tissue and the vascular network required to direct blood flow to active cells in skeletal muscle and the brain. We will also highlight the emerging central role that disruptions in capillary communication may play in blood flow dysregulation, pathophysiology, and disease.

Association between DLCO index and the severity of heart failure: a cross-sectional study

BACKGROUND

The prognostic role of diffusing capacity of the lung for carbon monoxide (DLCO) in heart failure has not been thoroughly investigated. Therefore, this study aimed to evaluate DLCO variation in different systolic and diastolic heart failure stages.

METHODS

This was a prospective cross-sectional study on 51 patients with systolic (reduced LVEF) or diastolic (preserved LVEF) chronic heart failure (CHF). All patients underwent a standard DLCO test. The associations between the severity of heart failure and reduced carbon monoxide transfer factor (TLCO), carbon monoxide transfer coefficient (KCO), and alveolar volume (VA) were investigated. Data were analysed using SPSS software version 16. p-Values below 0.05 were considered statistically significant.

RESULTS

The mean age of participants was 59.29 ± 14.91 years, with 72% of the study population being male. Systolic heart failure was observed in 47% of patients, diastolic heart failure in 18%, and a mixed systolic and diastolic pattern in 35%. There were significant differences between TLCO percentage in patients with CHF types and the New York Heart Association (NYHA) functional classes (p = 0.042). Overall, an ejection fraction (EF) of less than 25% correlated with 3%, 53%, and 0.78 declines in TLCO, KCO%, and KCO index, respectively.

CONCLUSION

Despite the lack of statistically significant differences between DLCO indices and CHF severity, decreased DLCO parameters correlated with reduced EF. Therefore, DLCO testing might be helpful to predict HF severity.

Traffic-related air pollution associated pulmonary pathophysiologic changes and cardiac injury in elderly patients with COPD

Traffic-related air pollution (TRAP) has shown enormous environmental toxicity, but its cardiorespiratory health impact on chronic obstructive pulmonary disease (COPD) has been less studied. We followed a panel of 45 COPD patients with 4 repeated clinical visits across 14 months in a traffic-predominated urban area of Beijing, China, with concurrent measurements of TRAP metrics (fine particulate matter, black carbon, oxides of nitrogen and carbon monoxide). Linear mixed-effect models were performed to evaluate the associations and potential pathways linking traffic pollution to indicators of spirometry, cardiac injury, inflammation and oxidative stress. We observed that interquartile range increases in moving averages of TRAP exposures at prior up to 7 days were associated with significant reductions in large and small airway functions, namely decreases in forced vital capacity of 3.1-9.3% and forced expiratory flow 25-75% of 5.9-16.4%. Higher TRAP levels were also associated with worsening of biomarkers relevant to lung injury (hepatocyte growth factor and surfactant protein D) and cardiac injury (high-sensitivity cardiac troponin I, B-type natriuretic peptide and soluble ST2), as well as enhanced airway/systemic inflammation and oxidative stress. Mediation analyses showed that TRAP exposures may prompt cardiac injury, possibly via worsening pulmonary pathophysiology. These findings highlight the importance of traffic pollution control priority in urban areas.

Heart transplantation in a patient with complex heart lung disease: a case report

Heart disease is often accompanied by lung disease as they share the same risk factors. Heart or lung transplantation is regarded as a definitive treatment for the end-stage disease of each, while the expected median survival for lung transplantation is far shorter than heart transplantation. We present a case of refractory heart failure along with severe obstructive and restrictive lung disease that showed dramatic improvement in pulmonary function after single heart transplantation.

Influence of reduced diffusing capacity and FEV1 on outcome after cardiac surgery

BACKGROUND

Impaired lung function is a well-known risk factor in cardiac surgery patients and reduced forced expiratory volume in 1 second (FEV₁ ) is associated with increased mortality. However, there is limited knowledge regarding the influence of impaired diffusing capacity of the lungs for carbon monoxide (DLCO) in unselected cardiac surgery patients. The aim of this study was to investigate the association of impaired DLCO and/or reduced FEV₁ on post-operative mortality and morbidity in cardiac surgery patients.

METHODS

In a prospective cohort study, 390 patients scheduled for elective cardiac surgery underwent preoperative lung function test including spirometry and DLCO measurements. We defined reduced FEV₁ as FEV₁ below lower limit of normal (LLN) and impaired DLCO as DLCO <60% of predicted.

RESULTS

Mortality within 1 year (90-570 days) was significantly higher in patients with impaired DLCO (12% vs 3%, P = .010) and with reduced FEV₁ (9% vs 3%, P = .028). Mortality was higher in patients with impaired DLCO both in the presence and absence of FEV₁  < LLN. In multivariate analysis, only impaired DLCO [OR: 3.3, 95% confidence interval (CI) 1.4-7.5; P = .005] and age (OR: 1.1 per year, 95% CI 1.0-1.2; P = .001) were independent predictors of the combined outcome of mortality and prolonged intensive care unit (ICU) stay. Impaired DLCO was also associated with post-operative respiratory complications.

CONCLUSION

In patients undergoing elective cardiac surgery, preoperative impaired FEV₁ and DLCO were associated with increased mortality and morbidity. In multivariate analysis, only DLCO and age were independent predictors of a combined outcome of mortality and prolonged ICU stay.

Pulmonary Function Testing Pre-heart Transplant Predicts Posttransplant Survival

Supplemental Digital Content is available in the text.

Although pulmonary function testing (PFT) is typically performed for heart transplant evaluation, the prognostic utility of PFTs after transplantation is unknown. We evaluated whether PFT parameters were correlated with outcomes following heart transplantation.

Current clinical applications of spectral tissue Doppler echocardiography (E/e' ratio) as a noninvasive surrogate for left ventricular diastolic pressures in the diagnosis of heart failure with preserved ejection fraction. Revisited 15 years later

It is currently well established that more than half of heart failure patients have preserved ejection fraction. The diagnosis of heart failure with preserved ejection fraction is complex in clinical practice despite ESC recommendations issued in 2019. In this context, the demonstration of increased left ventricular filling pressures at rest or during exercise allows a definite diagnosis of heart failure with preserved ejection fraction in patients with signs and/or symptoms compatible with the diagnosis and a preserved ejection fraction. The spectral tissue Doppler-derived E/e' ratio by transthoracic Doppler echocardiography has been validated in the noninvasive assessment of left ventricular diastolic pressures at rest and during exercise. Several studies report the validity of E/e' in the diagnosis of heart failure with preserved ejection fraction in patients with both isolated exertional and acute dyspnea, as well as in risk stratification. In light of the current literature, E/e' deserves to be included on every transthoracic Doppler echocardiography report in patients with suspected heart failure with preserved ejection fraction. This updated review provides an overview of the diagnostic relevance of E/e' in patients in its two modes of clinical presentation, isolated exertional dyspnea and the decompensated congestive form.

The clinical characteristics and outcomes of heart failure patient with chronic obstructive pulmonary disease from the Japanese community-based registry

Both heart failure (HF) and chronic obstructive pulmonary disease (COPD) are common diseases, but few studies have assessed the relationship between COPD and outcomes in patients with acute HF, especially in relation to age or ejection fraction (EF). The Kitakawachi Clinical Background and Outcome of Heart Failure Registry was a prospective, multicenter, community-based cohort and enrolled a total of 1,102 patients with acute HF between 2015 and 2017 in this study. The primary endpoint was defined as a composite endpoint that included all-cause mortality and hospitalization for HF. We stratified patients into two groups: those aged ≥ 80 years (elderly) and < 80 years (nonelderly). HF with preserved EF (HFpEF) was defined as EF ≥ 50%, whereas HF with reduced ejection fraction (HFrEF) was defined as EF < 50%. A total of 159 patients (14.4%) with COPD and 943 patients (83.6%) without COPD were included. COPD was found to be independently associated with a higher risk of the composite endpoint (adjusted hazard ratio: 1.42, 95% confidence interval: 1.14-1.77; p = 0.003). During a subgroup analysis, COPD was exposed as an independent risk factor of the composite endpoint in nonelderly patients; however, there was not such a finding observed among elderly patients. Separately, there was a significant association with COPD and the composite endpoint in patients with HFpEF. COPD showed a significantly higher risk of the composite endpoint after discharge in acute HF. However, this heightened risk was observable only in the subgroup of nonelderly patients and those of HFpEF.

The role of pulmonary function in patients with heart failure and preserved ejection fraction: Looking beyond chronic obstructive pulmonary disease

Background

The prognostic value of chronic obstructive pulmonary disease (COPD) as a comorbidity in heart failure has been well documented. However, the role of pulmonary function indices in patients with heart failure and preserved ejection fraction (HFpEF) remains to be elucidated.

Methods

Subjects with HFpEF received pulmonary function tests and echocardiogram. Total lung capacity (TLC), residual volume (RV), forced expiratory flow rate between 25% and 75% of vital capacity (FEF25-75), forced expiratory volume in the 1^st second (FEV1), forced vital capacity (FVC), and vital capacity (VC) were measured. Echocardiographic indices, including pulmonary artery systolic pressure (PASP), the ratio of early ventricular filling flow velocity to the septal mitral annulus tissue velocity (E/e’), and left ventricular mass (LVM), were recorded. National Death Registry was linked for the identification of mortality.

Results

A total of 1194 patients (72.4±13.2 years, 59% men) were enrolled. PASP, E/e’ and LVM were associated with either obstructive (RV/TLC, FEV1 and FEF25-75) or restrictive (VC and TLC) ventilatory indices. During a mean follow-up of 23.0±12.8 months, 182 patients died. Subjects with COPD had a lower survival rate than those without COPD. While VC, FVC, RV/TLC, and FEV1 were all independently associated with all-cause mortality in patients without COPD, only FEF25-75 was predictive of outcomes in those with COPD.

Conclusions

The abnormalities of pulmonary function were related to the cardiac hemodynamics in patients with HFpEF. In addition, these ventilatory indices were independently associated with long-term mortality, especially in those without COPD.

Bao Yuan decoction and Tao Hong Si Wu decoction improve lung structural remodeling in a rat model of myocardial infarction: Possible involvement of suppression of inflammation and fibrosis and regulation of the TGF-β1/Smad3 and NF-κB pathways

Chronic heart failure (CHF) leads to pulmonary structural remodeling, which may be a key factor for poor clinical outcomes in patients with end-stage heart failure, and few effective therapeutic options are presently available. The aim of the current study was to explore the mechanism of action and pulmonary-protective effects of treatment with Bao Yuan decoction combined with Tao Hong Si Wu decoction (BYTH) on lung structural remodeling in rats with ischemic heart failure. In a model of myocardial infarction (MI) induced by ligation of the left anterior descending (LAD) artery, rats were treated with BYTH. Heart function and morphometry were measured followed by echocardiography, histological staining, and immunohistochemical analysis of lung sections. The levels of transforming growth factor-β1 (TGF-β1), type I collagen, phosphorylated-Smad3 (p-Smad3), tumor necrosis factor-α (TNF-α), toll-like receptor 4 (TLR4), active nuclear factor κB (NF-κB) and alpha smooth muscle actin (α-SMA) were detected using Western blotting. Lung weight increased after an infarct with no evidence of pulmonary edema and returned to normal as a result of BYTH. In addition, BYTH treatment reduced levels of type I collagen, TGF-β1, and α-SMA expression and decreased the phosphorylation of Smad3 in the lungs of rats after MI. BYTH treatment also reduced the elevated levels of lung inflammatory mediators such as TNF-α, TLR4, and NF-κB. Results suggested that BYTH could effectively improve lung structural remodeling after MI because of its anti-inflammatory and anti-fibrotic action, which may be mediated by suppression of the TGF-β1/Smad3 and NF-κB signaling pathways.

Lung diffusion capacity in advanced heart failure: relation to central haemodynamics and outcome

Aims

Patients with heart failure (HF) are known to have a reduced pulmonary diffusion capacity for carbon monoxide (D_LCO), but little is known about how lung function relates to central haemodynamics. The aim of this study was to investigate the association between haemodynamic variables and pulmonary diffusion capacity adjusted for alveolar volume in congestive HF patients and to analyse how predicted D_LCO/V_A affects mortality in relation to the haemodynamic status.

Methods and results

We retrospectively studied right heart catheterization (RHC) and lung function data on 262 HF patients (mean age 51 ± 13 years) with a left ventricular ejection fraction < 45% referred non‐urgently for evaluation for heart transplantation (HTX) or left ventricular assist device (LVAD). Univariate and multivariate linear regression models were constructed to examine the associations between predicted values of D_LCO/V_A, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁), and haemodynamic parameters [pulmonary capillary wedge pressure (PCWP), central venous pressure, cardiac index, mean pulmonary artery pressure, and mean arterial pressure] as well as other factors known to affect lung function in HF. FEV₁ was reduced to <80% of predicted value in 55% of the population, and D_LCO/V_A was reduced in 63% of the population. D_LCO/V_A correlated positively with pulmonary capillary wedge pressure in both univariate and multivariate analyses for all included patients (P < 0.001 and P = 0.045, respectively) and a restricted population of patients with the shortest time between RHC and lung function testing (P = 0.005, P = 0.015). D_LCO/V_A predicted mortality in multivariate models [hazard ratio 1.5 (1.1–2.1)] but not the combined endpoint of death, LVAD implantation, or HTX. There was no significant correlation between haemodynamics and predicted FVC or FEV₁.

Conclusions

Pulmonary diffusion capacity correlates positively with left ventricular fillings pressures, and reduced values predict increased mortality in patients with HF. This might be driven by increased lung capillary volume in patients with pulmonary congestion.

Lung-diffusing capacity for carbon monoxide predicts early complications after cardiac surgery

PURPOSE

Preoperative pulmonary dysfunction has been associated with increased operative mortality and morbidity after cardiac surgery. This study aimed to determine whether values for the diffusing capacity of the lung for carbon monoxide (DL_CO) could predict postoperative complications after cardiac surgery.

METHODS

This study included 408 consecutive patients who underwent cardiac surgery between June 2008 and December 2015. DL_CO was routinely determined in all patients. A reduced DL_CO was clinically defined as %DL_CO < 70%. %DL_CO was calculated as DL_CO divided by the predicted DL_CO. The association between %DL_CO and in-hospital mortality was assessed, and independent predictors of complications were identified by a logistic regression analysis.

RESULTS

Among the 408 patients, 338 and 70 had %DL_CO values of ≥ 70% and < 70%, respectively. Complications were associated with in-hospital mortality (P < 0.001), but not %DL_CO (P = 0.275). A multivariate logistic regression analysis with propensity score matching identified reduced DL_CO as an independent predictor of complications (OR, 3.270; 95%CI, 1.356-7.882; P = 0.008).

CONCLUSIONS

%DL_CO is a powerful predictor of postoperative complications. The preoperative DL_CO values might provide information that can be used to accurately predict the prognosis after cardiac surgery.

CLINICAL TRIAL REGISTRATION NUMBER

UMIN000029985.

Preliminary evidence that hydrostatic edema may contribute to the formation of diffuse alveolar damage in a Holstein calf model

Background: Two notable findings of clinically healthy feedlot cattle suggest they may have pulmonary hydrostatic edema during the finishing phase of production: increased pulmonary arterial wedge pressures and pulmonary venous hypertrophy. The goal of this study was to determine if increased pulmonary arterial wedge pressure (PAWP) in a Holstein calf could lead to diffuse alveolar damage consistent with the early, exudative phase of acute interstitial pneumonia of feedlot cattle.

Methods: Six male Holstein dairy calves were given daily subcutaneous injections of the nonspecific ß-adrenergic agonist isoprenaline (10 mg/kg/d), to induce left ventricular diastolic dysfunction, or sterile water for 14 days. On Day 14, pulmonary arterial pressures and wedge pressures were measured, echocardiography performed, and the ratio of mitral valve flow velocity (E) to septal lengthening velocity (e’) calculated. Calves were euthanized on Day 15 and lung lesions semi-quantitatively scored.

Results: Mean PAWP was 12 ± 1 mm Hg in calves that received isoprenaline and 7 ± 1 mm Hg in controls ( P = 0.01). Calves that received isoprenaline tended to have greater relative wall thickness than control calves ( P = 0.15) and greater E/e’ ratios ( P = 0.16), suggestive of concentric hypertrophy and diastolic dysfunction, respectively. Calves that received isoprenaline also tended to have a left ventricle and interventricular septum that was 29 ± 10 g heavier than control calves ( P = 0.10) when controlling for body mass. Hyaline membranes, the hallmark feature of diffuse alveolar damage, were evident in lung sections from all calves that received isoprenaline but none of the controls.

Conclusions: Consistent with prior pathological and physiological studies of feedlot cattle, this study provides preliminary evidence that cattle presenting with clinical signs and pathology consistent with early stage acute interstitial pneumonia could be attributable to hydrostatic edema associated with left ventricular failure.

Pulmonary disease in HIV-infected adults in the era of antiretroviral therapy

: HIV in the antiretroviral therapy era is characterized by multimorbidity and the frequent occurrence of HIV-associated non-AIDS chronic health conditions. Respiratory symptoms and chronic pulmonary diseases, including chronic obstructive pulmonary disease, asthma, and cardiopulmonary dysfunction, are among the conditions that may present in persons living with HIV. Tobacco smoking, which is disproportionately high among persons living HIV, strongly contributes to the risk of pulmonary disease. Additionally, features associated with and at times unique to HIV, including persistent inflammation, immune cell activation, oxidative stress, and dysbiosis, may also contribute. This review summarizes the available literature regarding epidemiology of and risk factors for respiratory symptoms and chronic pulmonary disease in the current era.

Impact of systolic pulmonary artery pressure on all-cause mortality in elderly cardiac patients

OBJECTIVE

Elevated systolic pulmonary artery pressure (sPAP) is common among elderly patients with cardiac and pulmonary diseases. The lowest level of sPAP associated with increased mortality rate in octogenarians with cardiac diseases is however not sufficiently studied. Therefore, the present study aimed to identify the lowest level of sPAP associated with increased 5-year all-cause mortality in this patient group.

DESIGN

Of 538 octogenarians presented at the three Sahlgrenska University Hospitals (Sahlgrenska, Östra and Mölndal) with either congestive heart failure (CHF) or acute coronary syndrome (ACS), only 302 patients who had undergone echocardiography with data on sPAP were included in the present study. In order to identify the lowest level of sPAP associated with increased mortality rate, Cox proportional-hazard regression multivariable models were built for sPAP levels as low as 30 mmHg and upward with 5 mmHg intervals.

RESULTS

sPAP >35 mmHg was identified as the lowest level associated with increased 5-year all-cause mortality (HR = 1.7, 95% of CI = 1.1-2.6 and p = .013). Every increase of 5 mmHg in sPAP was associated with a 10% increased relative risk for all-cause mortality.

CONCLUSIONS

In octogenarians with cardiac diseases the lowest level of sPAP associated with increased all-cause mortality was >35 mmHg and the mortality rate increased with increasing sPAP.

Impairment of pulmonary diffusion correlates with hypoxemic burden in central sleep apnea heart failure patients

PURPOSE

Central sleep apnea (CSA) and Cheyne-Stokes respiration (CSR) are highly prevalent in heart failure (HF) and are linked to increased mortality. Impaired pulmonary diffusion capacity [DLCO] and [KCO]) have been suggested to play a key role in CSA-CSR pathophysiology. This study investigated the relationship between HF, CSR, DLCO and KCO in well-characterized HF patients.

METHODS

This prospective study included HF patients with CSR, all patients underwent full overnight polysomnography (PSG) and lung function testing.

RESULTS

A total of 100 patients were included (age 70.7±9.7years, 95% male, body mass index 28.9±5.3kg/m², left ventricular ejection fraction 33.5±7.7%, New York Heart Association class III 65%. DLCO and oxygenation were significantly correlated with hypoxemic burden (p<0.05). Mean oxygen saturation, oxygen desaturation, C-reactive protein level and pH were significantly associated with CSA-CSR severity (p<0.05).

CONCLUSION

The finding that lung diffusion capacity is significantly associated with hypoxemic burden in HF patients with CSA-CSR highlights the important of lung function in HF patients.

Sleep apnoea in heart failure: To treat or not to treat?

Heart failure (HF) and sleep apnoea are common disorders which frequently coexist. Two main types of apnoea occur: one is obstructive which, through recurring episodes of snoring, hypoxaemia, large negative intra-thoracic pressures and arousals from sleep leading to downstream inflammatory and autonomic nervous system changes, is thought to be a causative factor to the development of systemic hypertension and HF. The other type of apnoea, Cheyne-Stokes respiration with central sleep apnoea (CSR-CSA), is characterized by an oscillatory pattern of ventilation with a prevailing hyperventilation-induced hypocapnia, often in the absence of significant hypoxaemia and snoring, and is thought to be a consequence of advanced HF-related low cardiac output, high sympathetic nervous system activation and pulmonary congestion. CSR-CSA may be a compensatory response to advanced HF. Rostral fluid shift during sleep may play an important role in the pathogenesis of both obstructive sleep apnoea (OSA) and CSA. Studies of positive airway pressure (PAP) treatment of OSA and CSA in HF have shown short-term improvements in cardiac and autonomic function; however, there is no evidence of improved survival. Loop gain may provide useful marker of continuous PAP (CPAP) responsiveness in patients with central apnoea. A greater understanding of the pathophysiology of the interaction between obstructive and central apnoea and the various types of HF, and the mechanisms of therapies, such as PAP, is required to develop new strategies to overcome the disabling symptoms, and perhaps improve the mortality, that accompany HF with sleep apnoea.

Pulmonary Vascular Congestion: A Mechanism for Distal Lung Unit Dysfunction in Obesity

RATIONALE

Obesity is characterized by increased systemic and pulmonary blood volumes (pulmonary vascular congestion). Concomitant abnormal alveolar membrane diffusion suggests subclinical interstitial edema. In this setting, functional abnormalities should encompass the entire distal lung including the airways.

OBJECTIVES

We hypothesize that in obesity: 1) pulmonary vascular congestion will affect the distal lung unit with concordant alveolar membrane and distal airway abnormalities; and 2) the degree of pulmonary congestion and membrane dysfunction will relate to the cardiac response.

METHODS

54 non-smoking obese subjects underwent spirometry, impulse oscillometry (IOS), diffusion capacity (DLCO) with partition into membrane diffusion (DM) and capillary blood volume (VC), and cardiac MRI (n = 24). Alveolar-capillary membrane efficiency was assessed by calculation of DM/VC.

MEASUREMENTS AND MAIN RESULTS

Mean age was 45±12 years; mean BMI was 44.8±7 kg/m2. Vital capacity was 88±13% predicted with reduction in functional residual capacity (58±12% predicted). Despite normal DLCO (98±18% predicted), VC was elevated (135±31% predicted) while DM averaged 94±22% predicted. DM/VC varied from 0.4 to 1.4 with high values reflecting recruitment of alveolar membrane and low values indicating alveolar membrane dysfunction. The most abnormal IOS (R5 and X5) occurred in subjects with lowest DM/VC (r2 = 0.31, p<0.001; r2 = 0.34, p<0.001). Cardiac output and index (cardiac output / body surface area) were directly related to DM/VC (r2 = 0.41, p<0.001; r2 = 0.19, p = 0.03). Subjects with lower DM/VC demonstrated a cardiac output that remained in the normal range despite presence of obesity.

CONCLUSIONS

Global dysfunction of the distal lung (alveolar membrane and distal airway) is associated with pulmonary vascular congestion and failure to achieve the high output state of obesity. Pulmonary vascular congestion and consequent fluid transudation and/or alterations in the structure of the alveolar capillary membrane may be considered often unrecognized causes of airway dysfunction in obesity.

Exhaled Acetone Concentration Is Related to Hemodynamic Severity in Patients With Non-Ischemic Chronic Heart Failure

BACKGROUND

We hypothesized that exhaled acetone concentration (EAC), reflecting altered blood ketone body metabolism and increased acetone exhaust because of pulmonary congestion in heart failure (HF), would correlate with hemodynamic parameters in patients with non-ischemic chronic HF.

METHODS AND RESULTS

We prospectively enrolled 102 non-ischemic HF patients with New York Heart Association (NYHA) class I-III. Exhaled breath was collected after an overnight fast. Echocardiography and cardiac catheterization were performed in all patients. We also enrolled 17 control patients without HF. EAC in the HF patients was significantly higher than that in the control patients (median EAC; 0.53 vs. 0.38 ppm, P=0.012). EAC positively correlated with blood total ketone bodies (r=0.454, P<0.001), NYHA class (r=0.489, P<0.001), and plasma B-type natriuretic peptide (r=0.316, P=0.001). Right heart catheterization revealed that EAC significantly correlated with pulmonary capillary wedge pressure (PCWP, r=0.377, P<0.001). Receiver-operating characteristic analysis revealed that EAC >1.05 ppm was associated with PCWP ≥18 mmHg (area under the curve [AUC] 0.726, sensitivity 50%, specificity 89%). EAC was shown to be a comparable diagnostic biomarker for HF to BNP (AUC 0.760, sensitivity 80%, specificity 70%).

CONCLUSIONS

EAC may be a novel noninvasive biomarker that correlates hemodynamic severity in non-ischemic chronic HF. (Circ J 2016; 80: 1178-1186).

Fluid and electrolyte overload in critically ill patients: An overview

Fluids are considered the cornerstone of therapy for many shock states, particularly states that are associated with relative or absolute hypovolemia. Fluids are also commonly used for many other purposes, such as renal protection from endogenous and exogenous substances, for the safe dilution of medications and as “maintenance” fluids. However, a large amount of evidence from the last decade has shown that fluids can have deleterious effects on several organ functions, both from excessive amounts of fluids and from their non-physiological electrolyte composition. Additionally, fluid prescription is more common in patients with systemic inflammatory response syndrome whose kidneys may have impaired mechanisms of electrolyte and free water excretion. These processes have been studied as separate entities (hypernatremia, hyperchloremic acidosis and progressive fluid accumulation) leading to worse outcomes in many clinical scenarios, including but not limited to acute kidney injury, worsening respiratory function, higher mortality and higher hospital and intensive care unit length-of-stays. In this review, we synthesize this evidence and describe this phenomenon as fluid and electrolyte overload with potentially deleterious effects. Finally, we propose a strategy to safely use fluids and thereafter wean patients from fluids, along with other caveats to be considered when dealing with fluids in the intensive care unit.

Editor's Choice-Recent therapeutic trials on fluid removal and vasodilation in acute heart failure

Recent therapeutic trials regarding the management of acute heart failure (AHF) failed to demonstrate the efficacy of newer therapeutic modalities and agents. Low- versus high-dose and continuous administration of furosemide were shown not to matter. Ultrafiltration was not found to be more efficacious than sophisticated diuretic therapy including dose-adjusted intravenous furosemide and metolazone. Dopamine and nesiritide were not shown to be superior to current therapy. Tezosentan and tovalptan had no effect on mortality. The development of rolofylline was terminated due to adverse effect (seizures). Lastly, preliminary experience with serelaxin indicates a mortality improvement at six months that remains to be confirmed. The disappointing findings of these recent trials may reflect the lack of efficacy of newer therapeutic modalities and agents. Alternatively the disappointing findings of these recent trials may be in part due to methodological issues. The AHF syndrome is complex with many clinical phenotypes. Failure to match clinical phenotypes and therapeutic modalities is likely to be partly responsible for the disappointing findings of recent AHF trials.

Differences in clinical characteristics, management and short-term outcome between acute heart failure patients chronic obstructive pulmonary disease and those without this co-morbidity

AIM-METHODS

ALARM-HF was a retrospective, observational registry that included 4,953 patients admitted for acute heart failure (AHF) in six European countries, Turkey, Mexico and Australia. Data about respiratory disorders and related medications were available for 4,616 patients with AHF.

RESULTS

Chronic obstructive pulmonary disease (COPD) patients (n = 1,143, 24.8%) were older and more frequently men (p < 0.001) when compared to non-COPD patients. Despite the equivalent left ventricular ejection fraction (38.6 ± 13.7 vs. 38.2 ± 14.5%, p > 0.05), COPD patients more frequently presented with acutely decompensated heart failure (p < 0.001). Moreover, a worse cardiovascular profile was observed in the COPD group, including more atrial fibrillation/flutter, diabetes, hypertension, obesity, peripheral vascular disease (p < 0.001). Before admission, a higher percentage of COPD patients had experienced infections (25.0 vs. 14.0 %, p < 0.001), and were more likely to receive diuretics (p = 0.006), ACE inhibitors (p = 0.042), nitrates (p = 0.003), and digoxin (p = 0.034). With the exception of ACE inhibitors, those differences maintained at discharge, with concomitant increase in ARBs prescription (p = 0.01). Notably, β-blockers were less prescribed before admission (21.1 vs. 23.8%, p = 0.055) in COPD patients, and remained underutilized at discharge (p < 0.001). Correcting for baseline differences, all-cause in-hospital mortality did not differ between COPD and non-COPD groups (10.1 vs. 10.9%, p = 0.085).

CONCLUSION

A large proportion of AHF patients presented with concomitant COPD, had different clinical characteristics/co-morbidities, and less frequently received evidence-based pharmacological therapy compared to non-COPD patients. However, the in-hospital mortality was not higher in COPD group.

Lung capillary injury and repair in left heart disease: a new target for therapy?

The lungs are the primary organs affected in LHD (left heart disease). Increased left atrial pressure leads to pulmonary alveolar–capillary stress failure, resulting in cycles of alveolar wall injury and repair. The reparative process causes the proliferation of MYFs (myofibroblasts) with fibrosis and extracellular matrix deposition, resulting in thickening of the alveolar wall. Although the resultant reduction in vascular permeability is initially protective against pulmonary oedema, the process becomes maladaptive causing a restrictive lung syndrome with impaired gas exchange. This pathological process may also contribute to PH (pulmonary hypertension) due to LHD. Few clinical trials have specifically evaluated lung structural remodelling and the effect of related therapies in LHD. Currently approved treatment for chronic HF (heart failure) may have direct beneficial effects on lung structural remodelling. In the future, novel therapies specifically targeting the remodelling processes may potentially be utilized. In the present review, we summarize data supporting the clinical importance and pathophysiological mechanisms of lung structural remodelling in LHD and propose that this pathophysiological process should be explored further in pre-clinical studies and future therapeutic trials.

Pulmonary production of osteopontin in humans: effects of left ventricular systolic dysfunction and cardiopulmonary bypass

BACKGROUND

We evaluated pulmonary production of osteopontin (OPN) in left ventricular systolic dysfunction (LVSD) and after cardiopulmonary bypass surgery (CPB). OPN is a phosphoglycoprotein involved in inflammation and remodeling. In subjects with LVSD, plasma OPN correlates with prognosis but its origin is unknown. We hypothesized that the lungs produce OPN and that this could be affected by LVSD and CPB.

METHODS AND RESULTS

Subjects with (n = 57; left ventricular ejection fraction [LVEF] 32 ± 8%) and without (n = 63; LVEF 59 ± 7%) LVSD were studied during CPB. Arterial and venous OPN plasma levels were determined. Arterial and venous OPN levels were higher in LVSD (P = .0290). For both groups, levels dropped 1 hour after surgery and nearly doubled 24 hours after (P < .0001 vs basal). Notably, there was a significant positive arteriovenous gradient with arterial levels higher than venous levels. Arteriovenous differences were statistically significant at baseline (P = .0120) and 1 hour (P < .0001) but not at 24 hours (P = .0649). Arterial levels in heart failure correlated inversely with renal function (P = .016) and positively with mean pulmonary pressure (P = .028), heart rate (P = .036), and C-reactive protein (P = .047).

CONCLUSIONS

There is production of circulating OPN by the lungs, unaffected by LVSD or CPB. This likely represents an overflow from local lung production and does not contribute to increased levels in LVSD or after CPB.

Effect of cardiac resynchronization therapy on pulmonary function in patients with heart failure

Pulmonary congestion due to heart failure causes abnormal lung function. Cardiac resynchronization therapy (CRT) is a proven effective treatment for heart failure. The aim of this study was to test the hypothesis that CRT promotes increased lung volumes, bronchial conductance, and gas diffusion. Forty-four consecutive patients with heart failure were prospectively investigated before and after CRT. Spirometry, gas diffusion (diffusing capacity for carbon monoxide), cardiopulmonary exercise testing, New York Heart Association class, brain natriuretic peptide, the left ventricular ejection fraction, left atrial volume, and right ventricular systolic pressure were assessed before and 4 to 6 months after CRT. Pre- and post-CRT measures were compared using either paired Student's t tests or Wilcoxon's matched-pair test; p values <0.05 were considered significant. Improved New York Heart Association class, left ventricular ejection fraction, left atrial volume, right ventricular systolic pressure, and brain natriuretic peptide were observed after CRT (p <0.05 for all). Spirometry after CRT demonstrated increased percentage predicted total lung capacity (90 ± 17% vs 96 ± 15%, p <0.01) and percentage predicted forced vital capacity (80 ± 19% vs 90 ± 19%, p <0.01). Increased percentage predicted total lung capacity was significantly correlated with increased peak exercise end-tidal carbon dioxide (r = 0.43, p = 0.05). Increased percentage predicted forced vital capacity was significantly correlated with decreased right ventricular systolic pressure (r = -0.30, p = 0.05), body mass index (r = -0.35, p = 0.02) and creatinine (r = -0.49, p = 0.02), consistent with an association of improved bronchial conductance and decreased congestion. Diffusing capacity for carbon monoxide did not significantly change. In conclusion, increased lung volumes and bronchial conductance due to decreased pulmonary congestion and increased intrathoracic space contribute to an improved breathing pattern and decreased hyperventilation after CRT. Persistent alveolar-capillary membrane remodeling may account for unchanged diffusing capacity for carbon monoxide.

Heart failure and chronic obstructive pulmonary disease: the challenges facing physicians and health services

Pulmonary disease is common in patients with heart failure, through shared risk factors and pathophysiological mechanisms. Adverse pulmonary vascular remodelling and chronic systemic inflammation characterize both diseases. Concurrent chronic obstructive pulmonary disease presents diagnostic and therapeutic challenges, and is associated with increased morbidity and mortality. The cornerstones of therapy are beta-blockers and beta-agonists, whose pharmacological properties are diametrically opposed. Each disease is implicated in exacerbations of the other condition, greatly increasing hospitalizations and associated health care costs. Such multimorbidity is a key challenge for health-care systems oriented towards the treatment of individual diseases. Early identification and treatment of cardiopulmonary disease may alleviate this burden. However, diagnostic and therapeutic strategies require further validation in patients with both conditions.

Respiratory physiology on a chip

Our current understanding of respiratory physiology and pathophysiological mechanisms of lung diseases is often limited by challenges in developing in vitro models faithful to the respiratory environment, both in cellular structure and physiological function. The recent establishment and adaptation of microfluidic-based in vitro devices (μFIVDs) of lung airways have enabled a wide range of developments in modern respiratory physiology. In this paper, we address recent efforts over the past decade aimed at advancing in vitro models of lung structure and airways using microfluidic technology and discuss their applications. We specifically focus on μFIVDs covering four major areas of respiratory physiology, namely, artificial lungs (AL), the air-liquid interface (ALI), liquid plugs and cellular injury, and the alveolar-capillary barrier (ACB).

Examination of the carbon monoxide diffusing capacity (DL(CO)) in relation to its KCO and VA components

The single-breath carbon monoxide diffusing capacity (DL(CO)) is the product of two measurements during breath holding at full inflation: (1) the rate constant for carbon monoxide uptake from alveolar gas (kco [minute(-1)]) and (2) the "accessible" alveolar volume (Va). kco expressed per mm Hg alveolar dry gas pressure (Pb*) as kco/Pb*, and then multiplied by Va, equals Dl(CO); thus, Dl(CO) divided by Va (DL(CO)/Va, also called Kco) is only kco/Pb* in different units, remaining, essentially, a rate constant. The notion that DL(CO)/Va "corrects" DL(CO) for reduced Va is physiologically incorrect, because DL(CO)/Va is not constant as Va changes; thus, the term Kco reflects the physiology more appropriately. Crucially, the same DL(CO) may occur with various combinations of Kco and Va, each suggesting different pathologies. Decreased Kco occurs in alveolar-capillary damage, microvascular pathology, or anemia. Increased Kco occurs with (1) failure to expand normal lungs to predicted full inflation (extrapulmonary restriction); or (2) increased capillary volume and flow, either globally (left-to-right intracardiac shunting) or from flow and volume diversion from lost or damaged units to surviving normal units (e.g., pneumonectomy). Decreased Va occurs in (1) reduced alveolar expansion, (2) alveolar damage or loss, or (3) maldistribution of inspired gases with airflow obstruction. Kco will be greater than 120% predicted in case 1, 100-120% in case 2, and 40-120% in case 3, depending on pathology. Kco and Va values should be available to clinicians, as fundamental to understanding the clinical implications of DL(CO). The diffusing capacity for nitric oxide (DL(NO)), and the DL(NO)/DL(CO) ratio, provide additional insights.

Força muscular respiratória e capacidade funcional em idosas hipertensas com sonolência diurna excessiva

O objetivo do estudo foi verificar se a sonolência diurna excessiva (SDE) afeta a capacidade funcional (CF) e força muscular respiratória entre idosas hipertensas. O estudo avaliou 32 idosas hipertensas, divididas em dois grupos (com SDE, n=17, 64,9±5,3 anos; e sem SDE, n=15, 65,9±5,5 anos), quanto a: força muscular respiratória, por manovacuometria; CF, pelo Questionário para avaliação de limitação das atividades e por testes de aptidão funcional; nível de atividade física, pelo questionário internacional de atividade física IPAQ; grau de SDE, pela escala de sonolência de Epworth; qualidade do sono, pelo índice de qualidade do sono de Pittsburgh; e intensidade do ronco, pela escala de ronco de Stanford. Os dois grupos, homogêneos quanto a características antropométricas e da hipertensão, foram comparados estatisticamente quanto a parâmetros de sono, pressões respiratórias máximas, nível de atividade física e CF. Foi encontrada diferença significativa na qualidade do sono (p=0,03), tendo as hipertensas com SDE qualidade de sono muito ruim; porém não foram encontradas diferenças significativas entre os grupos nas pressões inspiratória e expiratória máximas, nem quanto aos testes de CF. Conclui-se que a força dos músculos respiratórios não sofre alteração em decorrência da presença de SDE em idosas hipertensas e que essa sonolência não interfere na capacidade funcional.

Regulation of alveolar gas conductance by NO in man, as based on studies with NO donors and inhibitors of NO production

AIM

Nitric oxide (NO) is a mediator of the pulmonary vessel tone and permeability. We hypothesized that it may also regulate the alveolar-capillary membrane gas conductance and lung diffusion capacity.

METHODS

In 20 healthy subjects (age = 23 +/- 3 years) we measured lung diffusion capacity for carbon monoxide (DLco), its determinants (membrane conductance, D(m), and pulmonary capillary blood volume, V(c)), systolic pulmonary artery pressure (PAPs) and pulmonary vascular resistance (PVR). Measurements were performed before and after administration of N(g)-monomethyl-L-arginine (L-NMMA, 0.5 mg kg(-1) min(-1)), as a NO production inhibitor, and L-arginine (L-Arg, 0.5 mg kg(-1) min(1)) as a NO pathway activator. The effects of L-NMMA were also tested in combination with active L-Arg and inactive stereoisomer D-Arg vehicled by 150 mL of 5%d-glucose solution. For L-Arg and L-NMMA, saline (150 mL) was also tested as a vehicle.

RESULTS

L-NMMA reduced D(m) (-41%P < 0.01), DLco (-20%, P < 0.01) and cardiac output (CO), and increased PAPs and PVR. In 10 additional subjects, a dose of L-NMMA of 0.03 mg kg(-1) min(1) infused in the main stem of the pulmonary artery was able to lower D(m) (-32%, P < 0.01) despite no effect on PVR and CO. D(m) depression was significantly greater when L-NMMA was vehicled by saline than by glucose. L-Arg but not D-Arg abolished the effects of L-NMMA. L-Arg alone increased D(m) (+14%, P < 0.01).

CONCLUSION

The findings indicate that NO mediates the respiratory effects of L-NMMA and L-Arg, and is involved in the physiology of the alveolar-capillary membrane gas conductance in humans. NO deficiency may cause an excessive endothelial sodium exchange/water conduction and fluid leakage in alveolar interstitial space, lengthening the air-blood path and depressing diffusion capacity.

Heart failure and chronic obstructive pulmonary disease: diagnostic pitfalls and epidemiology

Heart failure (HF) and chronic obstructive pulmonary disease (COPD) are global epidemics incurring significant morbidity and mortality. The combination presents many diagnostic challenges. Clinical symptoms and signs frequently overlap. Evaluation of cardiac and pulmonary function is often problematic and occasionally misleading. Echocardiography and pulmonary function tests should be performed in every patient. Careful interpretation is required to avoid misdiagnosis and inappropriate treatment. Airflow obstruction, in particular, must be demonstrated when clinically euvolaemic. Very high and very low concentrations of natriuretic peptides have high positive and negative predictive values for diagnosing HF in those with both conditions. Intermediate values are less informative. Both conditions are systemic disorders with overlapping pathophysiological processes. In patients with HF, COPD is consistently an independent predictor of death and hospitalization. However, the impact on ischaemic and arrhythmic events is unknown. Greater collaboration is required between cardiologists and pulmonologists to better identify and manage concurrent HF and COPD. The resulting symptomatic and prognostic benefits outweigh those attainable by treating either condition alone.