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

Influence of Impaired Diffusing Capacity and Sleep-disordered Breathing on Nocturnal Hypoxemia and Health Outcomes in Men with and without Human Immunodeficiency Virus

Rationale: Nocturnal hypoxemia is common in sleep-disordered breathing (SDB) and is associated with increased morbidity and mortality. Although impaired diffusing capacity of the lung for carbon monoxide (DlCO) is associated with daytime hypoxemia, its influence on SDB-related nocturnal hypoxemia is not known. Objectives: To characterize the effects of DlCO impairment on SDB-related nocturnal hypoxemia and associated health outcomes. Methods: Data from a multicenter cohort of men with and without human immunodeficiency virus (HIV) infection, with concomitant measures of DlCO and home-based polysomnography (n = 544), were analyzed. Multivariable quantile regression models characterized associations between DlCO and several measures of SDB-related hypoxemia (e.g., total sleep time with oxygen saturation as measured by pulse oximetry [SpO2] < 90% [T90]). Structural equation models were used to assess associations of impaired DlCO and SDB-related hypoxemia measures with prevalent hypertension and type 2 diabetes. Results: DlCO impairment (<80% predicted) was associated with sleep-related hypoxemia. Participants with severe SDB (apnea-hypopnea index ⩾ 30 events/h) and impaired DlCO had higher T90 (median difference, 15.0% [95% confidence interval (CI), 10.3% to 19.7%]) and average SDB-related desaturation (median difference, 1.0 [95% CI, 0.5 to 1.5]) and lower nadir SpO2 (median difference, -8.2% [95% CI, -11.4% to -4.9%]) and average SpO2 during sleep (median difference, -1.1% [95% CI, -2.1% to -0.01%]) than those with severe SDB and preserved DlCO. Higher T90 was associated with higher adjusted odds of prevalent hypertension (odds ratio, 1.39 [95% CI, 1.14 to 1.70]) and type 2 diabetes (odds ratio, 1.25 [95% CI, 1.07 to 1.46]). Conclusions: DlCO impairment in severe SDB was associated with sleep-related hypoxemia, prevalent hypertension, and type 2 diabetes. Assessment of SDB should be considered in those with impaired DlCO to guide testing and risk stratification strategies.

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.

Contemporary Evidence and Practice on Right Heart Catheterization in Patients with Acute or Chronic Heart Failure

Heart failure (HF) has a global prevalence of 1-2%, and the incidence around the world is growing. The prevalence increases with age, from around 1% for those aged <55 years to >10% for those aged 70 years or over. Based on studies in hospitalized patients, about 50% of patients have heart failure with reduced ejection fraction (HFrEF), and 50% have heart failure with preserved ejection fraction (HFpEF). HF is associated with high morbidity and mortality, and HF-related hospitalizations are common, costly, and impact both quality of life and prognosis. More than 5-10% of patients deteriorate into advanced HF (AdHF) with worse outcomes, up to cardiogenic shock (CS) condition. Right heart catheterization (RHC) is essential to assess hemodynamics in the diagnosis and care of patients with HF. The aim of this article is to review the evidence on RHC in various clinical scenarios of patients with HF.

Importance of heart failure duration for development of pulmonary hypertension in advanced heart failure

BACKGROUND AND OBJECTIVES

Pulmonary vascular resistance (PVR) is critical when evaluating candidacy for advanced heart failure (HF) therapies, but risk factors for elevated PVR are not well studied. We hypothesized that HF duration would be associated with elevated PVR.

METHODS

Danish single-center registry of consecutive in- and outpatients undergoing right heart catheterization as part of advanced HF work up. The relation between HF duration and PVR was estimated by regression analysis. Finally, the relation between PVR and long-term mortality was assessed by Cox proportional hazards regression and Kaplan-Meier analyses.

RESULTS

A total of 549 patients (77% men, median age 54 (43-61) years, median HF duration 1.6 years (0.1-7.1)) were included. Univariate linear regression displayed an association between longer HF duration and increasing PVR (p = 0.014). PVR > 3 WU was present in 92 patients (17%) who were older (median p < 0.001) and had longer HF duration (p = 0.03). HF duration (per 1 year increase) did not predict PVR > 3 WU after adjustment for covariables (OR 1.00; p = 0.99). During a mean follow-up time of 4.5 years, there were 240 (44%) deaths. Increasing PVR was associated with elevated all-cause mortality risk (adjusted HR 1.24; p < 0.001). PVR > 3 WU was associated with higher mortality (adjusted HR 1.49; p = 0.027).

CONCLUSION

Longer duration of HF was associated with higher PVR in patients with advanced HF, but this association disappeared in multivariate analyses. Longer HF duration per se likely does not cause elevated PVR and should not discourage evaluation for heart transplantation.

Clinical Predictors and Outcomes After Left Ventricular Assist Device Implantation and Tracheostomy

BACKGROUND

Postoperative respiratory failure is a major complication that affects up to 10% of patients who undergo cardiac surgery and has a high in-hospital mortality rate. Few studies have investigated whether patients who require tracheostomy for postoperative respiratory failure after continuous-flow left ventricular assist device (CF-LVAD) implantation have worse survival outcomes than patients who do not.

OBJECTIVE

To identify risk factors for respiratory failure necessitating tracheostomy in CF-LVAD recipients and to compare survival outcomes between those who did and did not require tracheostomy.

METHODS

Consecutive patients who underwent primary CF-LVAD placement at a single institution between August 1, 2002, and December 31, 2019, were retrospectively reviewed. Propensity score matching accounted for baseline differences between the tracheostomy and nontracheostomy groups. Multivariate logistic regression was used to identify tracheostomy risk factors and 90-day survival; Kaplan-Meier analysis was used to assess midterm survival.

RESULTS

During the study period, 664 patients received a CF-LVAD; 106 (16.0%) underwent tracheostomy for respiratory failure. Propensity score matching produced 103 matched tracheostomy-nontracheostomy pairs. Patients who underwent tracheostomy were older (mean [SD] age, 57.9 [12.3] vs 54.6 [13.9] years; P = .02) and more likely to need preoperative mechanical circulatory support (61.3% vs 47.8%; P = .01) and preoperative intubation (27.4% vs 8.8%; P < .001); serum creatinine was higher in the tracheostomy group (mean [SD], 1.7 [1.0] vs 1.4 [0.6] mg/dL; P < .001), correlating with tracheostomy need (odds ratio, 1.76; 95% CI, 1.21-2.56; P = .003). Both before and after propensity matching, 30-day, 60-day, 90-day, and 1-year survival were worse in patients who underwent tracheostomy. Median follow-up was 0.8 years (range, 0.0-11.2 years). Three-year Kaplan-Meier survival was significantly worse for the tracheostomy group before (22.0% vs 61.0%; P < .001) and after (22.4% vs 48.3%; P < .001) matching.

CONCLUSION

Given the substantially increased probability of death in patients who develop respiratory failure and need tracheostomy, those at high risk for respiratory failure should be carefully considered for CF-LVAD implantation. Comprehensive management to decrease respiratory failure before and after surgery is critical.

The Year in Cardiothoracic Transplant Anesthesia: Selected Highlights From 2021 Part II: Cardiac Transplantation

This article spotlights the research highlights of this year that specifically pertain to the specialty of anesthesia for heart transplantation. This includes the research on recent developments in the selection and optimization of donors and recipients, including the use of donation after cardiorespiratory death and extended criteria donors, the use of mechanical circulatory support and nonmechanical circulatory support as bridges to transplantation, the effect of COVID-19 on heart transplantation candidates and recipients, and new advances in the perioperative management of these patients, including the use of echocardiography and postoperative outcomes, focusing on renal and cerebral outcomes.

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.

Cheyne-stokes respiration in children with heart failure

Cheyne-Stokes respiration (CSA-CSR) is a form of central sleep apnea characterized by alternating periods of hyperventilation and central apneas or hypopneas. CSA-CSR develops following a cardiac insult resulting in a compensatory increase in sympathetic activity, which in susceptible patients causes hyperventilation and destabilizes respiratory control. The physiological changes that occur in CSA-CSR include hyperventilation, a reduced blood gas buffering capacity, and circulatory delay. In adults, 25% to 50% of patients with heart failure are reported to have CSA-CSR. The development of CSA-CSR in this group of patients is considered a poor prognostic sign. The prevalence, progression, and treatment outcomes of CSA-CSR in children remain unclear with only 11 children being described in the literature. The lack of data is possibly not due to the paucity of children with severe heart failure and CSA-CSR but because they may be under-recognized, compounded by the absence of routine polysomnographic assessment of children with moderate to severe heart failure. Building on much broader experience in the diagnosis and management of CSA-CSR in adult sleep medicine and our limited experience in a pediatric quaternary center, this paper will discuss the prevalence of CSA-CSR, its' treatment options, outcomes in children, and the potential future direction for research in this understudied area of pediatric sleep medicine.

Carbon Monoxide Diffusing Capacity Predicts Cardiac Readmission in Patients Undergoing Left Ventricular Assist Device Implantation in Japan

Carbon monoxide diffusion capacity (DLCO) is impaired in heart failure patients; however, its clinical impact has not been well investigated in the left ventricular assist device (LVAD) population. We explored the predictive value of preoperative DLCO in the survival and cardiac readmission rates after LVAD implantation. Seventy-six patients who received continuous-flow LVAD as bridge-to-transplant therapy from November 2007 to September 2018 and underwent pulmonary function test before LVAD implantation were included. The primary study endpoints were death and readmission for heart failure or arrhythmia (cardiac readmission). Patients were stratified into two groups according to the percent of predicted DLCO (%DLCO). Pulmonary vascular resistance (PVR) was equivocal between the groups preoperatively, whereas the low DLCO group (%DLCO < 80%) showed significantly high PVR postoperatively. The mortality rate was not different between the groups. The 2 year cardiac readmission rate was 33.5% in the low DLCO group and 8.7% in the high DLCO group (%DLCO ≥ 80%) (P = 0.028). The %DLCO was associated with cardiac readmission in univariate and multivariate analyses (hazard ratio: 4.32; 95% CI: 1.50-15.9; P = 0.005). Low %DLCO was associated with high PVR postoperatively and was a risk factor for cardiac readmission after LVAD implantation.

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.

Trajectory and mortality of preserved ratio impaired spirometry: the Rotterdam Study

Preserved ratio impaired spirometry (PRISm) is a heterogeneous condition but its course and disease progression remain to be elucidated. We aimed to examine its prevalence, trajectories and prognosis in the general population.In the Rotterdam Study (population-based prospective cohort) we examined prevalence, trajectories and prognosis of subjects with normal spirometry (controls; forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) ≥0.7, FEV₁  ≥80%), PRISm (FEV₁/FVC ≥0.7, FEV₁ <80%) and chronic obstructive pulmonary disease (COPD) (FEV₁/FVC <0.7) at two study visits. Hazard ratios with 95% confidence intervals for mortality (until December 30, 2018) were adjusted for age, sex, body mass index, current smoking and pack-years.Of 5487 subjects (age 69.1±8.9 years; 7.1% PRISm), 1603 were re-examined after 4.5 years. Of the re-examined PRISm subjects, 15.7% transitioned to normal spirometry and 49.4% to COPD. Median lung function decline was highest in subjects with incident PRISm (FEV₁ -92.8 mL·year^-1, interquartile range (IQR) -131.9- -65.8 mL·year^-1; FVC -93.3 mL·year^-1, IQR -159.8- -49.1 mL·year^-1), but similar in persistent PRISm (FEV₁ -30.2 mL·year^-1, IQR -67.9- -7.5 mL·year^-1; FVC -20.1 mL·year^-1, IQR -47.7-21.7 mL·year^-1) and persistent controls (FEV₁ -39.6 mL·year^-1, IQR -64.3--12.7 mL·year^-1; FVC -20.0 mL·year^-1, IQR -55.4-18.8 mL·year^-1). Of 5459 subjects with informed consent for follow-up, 692 (12.7%) died during 9.3 years (maximum) follow-up: 10.3% of controls, 18.7% of PRISm subjects and 20.8% of COPD subjects. Relative to controls, subjects with PRISm and COPD Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2-4 had increased all-cause mortality (PRISm: HR 1.6, 95% CI 1.2-2.0; COPD GOLD 2-4: HR 1.7, 95% CI 1.4-2.1) and cardiovascular mortality (PRISm: HR 2.8, 95% CI 1.5-5.1; COPD 2-4: HR 2.1, 95% CI 1.2-3.6). Mortality within <1 year was highest in PRISm, with patients often having cardiovascular comorbidities (heart failure or coronary heart disease; 70.0%).PRISm is associated with increased mortality and this population encompasses at least three distinct subsets: one that develops COPD during follow-up, a second with high cardiovascular burden and early mortality, and a third with persistent PRISm and normal age-related lung function decline.

The role of exercise hemodynamics in assessing patients with chronic heart failure and left ventricular assist devices

Introduction: Chronic heart failure is characterized by reduced exercise capacity. Invasive exercise hemodynamics are not routinely performed unless patients undergo transplant or left ventricular assist devices (LVAD) assessment, though now with readily available noninvasive devices, exercise hemodynamics are easily obtained. Our contention is that this is a valuable opportunity to acquire a more accurate measure of cardiac status in heart failure. Exercise hemodynamic measures such as cardiac power output can be carried out cheaply and effectively. Recent studies have highlighted the added value of exercise hemodynamics in prognostication of heart failure, and their role in assessing myocardial recovery in LVADs. Areas covered: In this review, we explore the literature available on Medline until 2019 focusing on resting and exercise hemodynamics alongside the methods of assessment (invasive and noninvasive) in heart failure with reduced ejection fraction and patients with implanted LVADs. Expert opinion: Hemodynamics measured both at rest and exercise are expected to play a significant role in the work up of transplant and LVAD patients. Furthermore, there is the potential to utilize noninvasive assessment in a complimentary fashion to support patient selection and improve the monitoring of response to treatment across the full cohort of heart failure patients.

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.