Left atrial reservoir pressure-volume relations during exercise in healthy older adults

The left atrium (LA) mediates cardiopulmonary interactions. During ventricular systole, the LA functions as a compliant reservoir that is coupled to the left ventricle (LV) and offloads volume from the pulmonary vasculature. We aimed to describe LA reservoir function using phasic relationships between pulmonary artery wedge pressure (PAWP) and LA volume events. We included healthy adults (7 M/6 F, 56 ± 8 yr) who were studied at rest and during semirecumbent cycle ergometry at a target of 100 beats/min heart rate. Right heart catheterization was performed to record the PAWP and two-dimensional (2-D) echocardiography was used to measure LA and LV volumes. We manually measured A-wave, x-trough, V-wave, and y-trough PAWP beat-by-beat, as well as minimal, maximal, and precontraction biplane LA volumes. Heart rate increased by 40 ± 7 beats/min with exercise; stroke volume and cardiac output also rose. Although all phasic PAWP measurements increased with exercise, the x-V pressure pulse during LA filling doubled from 4 ± 2 to 8 ± 4 mmHg (P = 0.001). LA minimal volume was unchanged but maximal volume increased from 39 ± 9 to 48 ± 9 mL (P < 0.001) with exercise, and so reservoir volume increased from 24 ± 5 to 32 ± 8 mL (P < 0.001). As such, calculated LA compliance decreased from 6.8 ± 3.4 to 4.8 ± 2.6 mL/mmHg (P = 0.029). The product of V-wave PAWP and LA maximal volume, a surrogate for LA wall stress, increased from 486 ± 193 to 953 ± 457 mmHg·mL (P < 0.001). In healthy older adults during submaximal exercise, the PAWP waveform shifts upward and its amplitude widens, LA filling increases, LA compliance decreases modestly, and LA wall stress may augment substantially.NEW & NOTEWORTHY We combined invasive estimates of left atrial pressure with noninvasive left atrial volume measurements made at rest and during exercise in healthy humans. Left atrial pressure and volume both increased with exercise, though the pressure increase was relatively greater, and calculated compliance decreased modestly while estimated peak wall stress nearly doubled. Our results demonstrate left atrial loading during exercise in healthy older adults and provide insight into how the left atrium mediates cardiopulmonary interactions.

Exercise and pulsatile pulmonary vascular loading in chronic thromboembolic pulmonary disease

Chronic thromboembolic pulmonary disease (CTEPD) is characterized by organized nonresolving thrombi in pulmonary arteries (PA). In CTEPD with pulmonary hypertension (PH), chronic thromboembolic PH (CTEPH), early wave reflection results in abnormalities of pulsatile afterload and augmented PA pressures. We hypothesized that exercise during right heart catheterization (RHC) would elicit more frequent elevations of pulsatile vascular afterload than resistive elevations in patients with CTEPD without PH. The interdependent physiology of pulmonary venous and PA hemodynamics was also evaluated. Consecutive patients with CTEPD without PH (resting mean PA pressure ≤20 mmHg) undergoing an exercise RHC were identified. Latent resistive and pulsatile abnormalities of pulmonary vascular afterload were defined as an exercise mean PA pressure/cardiac output >3 WU, and PA pulse pressure to PA wedge pressure (PA PP/PAWP) ratio >2.5, respectively. Forty-five patients (29% female, 53 ± 14 years) with CTEPD without PH were analyzed. With exercise, 19 patients had no abnormalities (ExNOR), 26 patients had abnormalities (ExABN) of pulsatile (20), resistive (2), or both (4) elements of pulmonary vascular afterload. Exercise elicited elevations of pulsatile afterload (53%) more commonly than resistive afterload (13%) (p < 0.001). ExABN patients had lower PA compliance and higher pulmonary vascular resistance at rest and exercise and prolonged resistance-compliance time product at rest. The physiological relationship between changes in PA pressures relative to PAWP was disrupted in the ExABN group. In CTEPD without PH, exercise RHC revealed latent pulmonary vascular afterload elevations in 58% of patients with more frequent augmentation of pulsatile than resistive pulmonary vascular afterload.

Unlocking the potential of RNA-based therapeutics in the lung: current status and future directions

Awareness of RNA-based therapies has increased after the widespread adoption of mRNA vaccines against SARS-CoV-2 during the COVID-19 pandemic. These mRNA vaccines had a significant impact on reducing lung disease and mortality. They highlighted the potential for rapid development of RNA-based therapies and advances in nanoparticle delivery systems. Along with the rapid advancement in RNA biology, including the description of noncoding RNAs as major products of the genome, this success presents an opportunity to highlight the potential of RNA as a therapeutic modality. Here, we review the expanding compendium of RNA-based therapies, their mechanisms of action and examples of application in the lung. The airways provide a convenient conduit for drug delivery to the lungs with decreased systemic exposure. This review will also describe other delivery methods, including local delivery to the pleura and delivery vehicles that can target the lung after systemic administration, each providing access options that are advantageous for a specific application. We present clinical trials of RNA-based therapy in lung disease and potential areas for future directions. This review aims to provide an overview that will bring together researchers and clinicians to advance this burgeoning field.

Alterations of pulmonary vascular afterload in exercise-induced pre- and post-capillary pulmonary hypertension

Exercise imposes increased pulmonary vascular afterload based on rises in pulmonary artery (PA) wedge pressure, declines in PA compliance, and resistance-compliance time. In health, afterload stress stabilizes during steady-state exercise. Our objective was to examine alterations of these exercise-associated stresses in states of pre- and post-capillary pulmonary hypertension (PH). PA hemodynamics were evaluated at rest, 2 and 7 min of steady-state exercise at moderate intensity in patients who exhibited Pre-capillary (n = 22) and post-capillary PH (n = 22). Patients with normal exercise hemodynamics (NOR-HD) (n = 32) were also studied. During exercise in all groups, PA wedge pressure increased at 2 min, with no further change at 7 min. In post-capillary PH and NOR-HD, increases in PA diastolic pressure and diastolic pressure gradient remained stable at 2 and 7 min of exercise, while in pre-capillary PH, both continued to increase at 7 min. The behavior of the diastolic pressure gradient was linearly related to the duration of resistance-compliance time at rest (r²  = 0.843) and exercise (r²  = 0.760). Exercise resistance-compliance time was longer in pre-capillary PH associated with larger increases in diastolic pressure gradient. Conversely, resistance-compliance time was shortest in post-capillary PH compared to pre-capillary PH and NOR-HD and associated with limited increases in exercise diastolic pressure gradient. During steady-state, modest-intensity exercise-specific patterns of pulmonary vascular afterload responses were observed in pre- and post-capillary PH relative to NOR-HD. Longer resistance-compliance time related to greater increases in PA diastolic pressure and diastolic pressure gradients in pre-capillary PH, while shorter resistance-compliance time appeared to limit these increases in post-capillary PH.

Measurement properties of the WHO Disability Assessment Schedule 2.0 for evaluating functional status after inpatient surgery

BACKGROUND

Expert recommendations propose the WHO Disability Assessment Schedule (WHODAS) 2.0 as a core outcome measure in surgical studies, yet data on its long-term measurement properties remain limited. These were evaluated in a secondary analysis of the Measurement of Exercise Tolerance before Surgery (METS) prospective cohort.

METHODS

Participants were adults (40 years of age or older) who underwent inpatient non-cardiac surgery. The 12-item WHODAS and EQ-5DTM-3L questionnaires were administered preoperatively (in person) and 1 year postoperatively (by telephone). Responsiveness was characterized using standardized response means (SRMs) and correlation coefficients between change scores. Construct validity was evaluated using correlation coefficients between 1-year scores and comparisons of WHODAS scores across clinically relevant subgroups.

RESULTS

The analysis included 546 patients. There was moderate correlation between changes in WHODAS and various EQ-5DTM subscales. The strongest correlation was between changes in WHODAS and changes in the functional domains of the EQ-5D-3L-for example, mobility (Spearman's rho 0.40, 95 per cent confidence interval [c.i.] 0.32 to 0.48) and usual activities (rho 0.45, 95 per cent c.i. 0.30 to 0.52). When compared across quartiles of EQ-5D index change, median WHODAS scores followed expected patterns of change. In subgroups with expected functional status changes, the WHODAS SRMs ranged from 'small' to 'large' in the expected directions of change. At 1 year, the WHODAS demonstrated convergence with the EQ-5D-3L functional domains, and good discrimination between patients with expected differences in functional status.

CONCLUSION

The WHODAS questionnaire has construct validity and responsiveness as a measure of functional status at 1 year after major surgery.

THE ROLE OF EXERCISE RIGHT HEART CATHETERIZATION TO GUIDE PULMONARY HYPERTENSION THERAPY IN OLDER ADULTS

The spectrum of patients referred for suspected pulmonary arterial hypertension (PAH) includes a population with clinical features suggestive of pulmonary hypertension due to left heart disease (PH‐LHD). Even after right heart catheterization (RHC) performed at rest, it can be a challenge to identify patients who will clearly benefit from PAH drug therapy. Therefore, the objective of this study was to evaluate the role of exercise RHC to influence decisions regarding prescription of PAH drug therapy in this population. A retrospective cohort study was conducted of older adults with risk factors for PH‐LHD and suspected PH referred for exercise RHC. One year follow‐up was conducted to record clinical outcomes, all changes in PAH drug therapy, and changes in patient‐reported quality of life. The final cohort included 61 patients, mean age of 69 ± 10; 44% and 34% had a history of coronary artery disease and atrial fibrillation respectively. Exercise changed the proportional breakdown of hemodynamic diagnoses from 36% No PH, 44% PAH, and 20% PH‐LHD at rest to 15% No PH, 36% PAH, and 49% PH‐LHD. Although a significant proportion of patients were reclassified as PH‐LHD, there was an overall increase in the proportion of patients receiving PAH drug therapy, particularly for those with PAH confirmed by exercise RHC. A total of 11 PAH drug prescriptions were employed before exercise RHC increasing to 24 after (p = 0.002). Patients receiving PAH therapy demonstrated significant improvement in self‐reported quality of life. Exercise RHC appeared to influence selection of PAH drug therapy.

Evaluation and management of patients with chronic thromboembolic pulmonary hypertension - consensus statement from the ISHLT

ISHLT members have recognized the importance of a consensus statement on the evaluation and management of patients with chronic thromboembolic pulmonary hypertension. The creation of this document required multiple steps, including the engagement of the ISHLT councils, approval by the Standards and Guidelines Committee, identification and selection of experts in the field, and the development of 6 working groups. Each working group provided a separate section based on an extensive literature search. These sections were then coalesced into a single document that was circulated to all members of the working groups. Key points were summarized at the end of each section. Due to the limited number of comparative trials in this field, the document was written as a literature review with expert opinion rather than based on level of evidence.

Prone transportation to an ECMO center

Acute Respiratory Distress Syndrome (ARDS) accounts for 10% of all intensive care unit admissions and mortality remains exceedingly high ranging from 35 to 46%. Prone positioning has demonstrated benefit as a treatment option in the moderate to severe subset of ARDS patients. Referral to an extracorporeal membrane oxygenation (ECMO) center remains the standard of care for patients with refractory hypoxemia. Transfer of these already critically ill patients is high risk but there is a possibility for improved oxygenation on transport with prone positioning. Currently there is limited data on the safe transportation of prone patients to ECMO centers. Herein we describe a case of an ARDS patient safely transported prone with minimal ad hoc adjustments to standard ambulance transport.

CLINICAL IMPLICATIONS OF BODY COMPOSITION AND EXERCISE CAPACITY FOLLOWING PULMONARY ENDARTERECTOMY

BACKGROUND

Pulmonary endarterectomy (PEA) is a curative procedure for patients with chronic thromboembolic pulmonary hypertension. Body composition and exercise capacity have been associated with adverse outcomes in patients undergoing cardiothoracic surgeries, but their significance with PEA is unclear. We evaluated the association of body composition and 6-minute walk distance (6MWD) with disease severity, hospital length of stay, discharge disposition and post-operative functional recovery.

METHODS

Retrospective, single-center cohort study of patients who underwent PEA (Jan/2014-Dec/2017). Body composition (skeletal muscle mass and adiposity cross sectional area, body mass index) was quantified using thoracic computed tomography with Slice-O-Matic software. Association of body composition measures and 6MWD with clinical outcomes was evaluated using multivariable regression models.

RESULTS

127 patients (58±14 years; 42% males, Body Mass Index: 31±7 kg/m², 6MWD: 361±165 m) were included. Muscle and 6MWD were associated with disease severity measures. Of those surviving hospitalization (n=125), a greater 6MWD was associated with a shorter hospital stay (1.9 median days per 100m, p<0.001) and higher likelihood of being discharged directly home from hospital (OR: 2.1 per 100m, p= 0.004), independent of age, sex and body mass index. Those with a lower pre-operative 6MWD (per 100m) had a greater increase in their post-operative 6MWD (52m, p< 0.0001), independent of age, sex, and body mass index. Body composition measures were not associated with hospital outcomes or exercise capacity in the first-year post-operatively.

CONCLUSIONS

Exercise capacity was a more prognositc marker of PEA outcomes compared to body composition. Future research is needed to explore pre-PEA rehabilitation strategies.

Quantitative assessment of pulmonary artery occlusion using lung dynamic perfusion CT

Quantitative measurement of lung perfusion is a promising tool to evaluate lung pathophysiology as well as to assess disease severity and monitor treatment. However, this novel technique has not been adopted clinically due to various technical and physiological challenges; and it is still in the early developmental phase where the correlation between lung pathophysiology and perfusion maps is being explored. The purpose of this research work is to quantify the impact of pulmonary artery occlusion on lung perfusion indices using lung dynamic perfusion CT (DPCT). We performed Lung DPCT in ten anesthetized, mechanically ventilated juvenile pigs (18.6–20.2 kg) with a range of reversible pulmonary artery occlusions (0%, 40–59%, 60–79%, 80–99%, and 100%) created with a balloon catheter. For each arterial occlusion, DPCT data was analyzed using first-pass kinetics to derive blood flow (BF), blood volume (BV) and mean transit time (MTT) perfusion maps. Two radiologists qualitatively assessed perfusion maps for the presence or absence of perfusion defects. Perfusion maps were also analyzed quantitatively using a linear segmented mixed model to determine the thresholds of arterial occlusion associated with perfusion derangement. Inter-observer agreement was assessed using Kappa statistics. Correlation between arterial occlusion and perfusion indices was evaluated using the Spearman-rank correlation coefficient. Our results determined that perfusion defects were detected qualitatively in BF, BV and MTT perfusion maps for occlusions larger than 55%, 80% and 55% respectively. Inter-observer agreement was very good with Kappa scores > 0.92. Quantitative analysis of the perfusion maps determined the arterial occlusion threshold for perfusion defects was 50%, 76% and 44% for BF, BV and MTT respectively. Spearman-rank correlation coefficients between arterial occlusion and normalized perfusion values were strong (− 0.92, − 0.72, and 0.78 for BF, BV and MTT, respectively) and were statically significant (p < 0.01). These findings demonstrate that lung DPCT enables quantification and stratification of pulmonary artery occlusion into three categories: mild, moderate and severe. Severe (occlusion ≥ 80%) alters all perfusion indices; mild (occlusion < 55%) has no detectable effect. Moderate (occlusion 55–80%) impacts BF and MTT but BV is preserved.

Normal and Abnormal Relationships of Pulmonary Artery to Wedge Pressure During Exercise

Background

Resting right heart catheterization can assess both left heart filling and pulmonary artery (PA) pressures to identify and classify pulmonary hypertension. Although exercise may further elucidate hemodynamic abnormalities, current pulmonary hypertension classifications do not consider the expected interrelationship between PA and left heart filling pressures. This study explored the utility of this relationship to enhance the classification of exercise hemodynamic phenotypes in pulmonary hypertension.

Methods and Results

Data from 36 healthy individuals (55, 50–60 years, 50% male) and 85 consecutive patients (60, 49–71 years, 48% male) with dyspnea and/or suspected pulmonary hypertension of uncertain etiology were analyzed. Right heart catheterization was performed at rest and during semiupright submaximal cycling. To classify exercise phenotypes in patients, upper 95% CIs were identified from the healthy individuals for the change from rest to exercise in mean PA pressure over cardiac output (ΔmPAP/ΔCO ≤3.2 Wood units [WU]), pulmonary artery wedge pressure over CO (ΔPAWP/ΔCO ≤2 mm Hg/L per minute), and exercise PA pulse pressure over PAWP (PP/PAWP ≤2.5). Among patients with a ΔmPAP/ΔCO ≤3.2 WU, the majority (84%) demonstrated a ΔPAWP/ΔCO ≤2 mm Hg/L per minute, yet 23% demonstrated an exercise PP/PAWP >2.5. Among patients with a ΔmPAP/ΔCO >3.2 WU, 37% had an exercise PP/PAWP >2.5 split between ΔPAWP/ΔCO groups. Patients with normal hemodynamic classification declined from 52% at rest to 36% with exercise.

Conclusions

The addition of PP/PAWP to classify exercise hemodynamics uncovers previously unrecognized abnormal phenotypes within each ΔmPAP/ΔCO group. Our study refines abnormal exercise hemodynamic phenotypes based on an understanding of the interrelationship between PA and left heart filling pressures.

Augmentation of pulmonary blood flow and cardiac output by non-invasive external ventilation late after Fontan palliation

Objectives

Although a life-preserving surgery for children with single ventricle physiology, the Fontan palliation is associated with striking morbidity and mortality with advancing age. Our primary objective was to evaluate the impact of non-invasive, external, thoraco-abdominal ventilation on pulmonary blood flow (PBF) and cardiac output (CO) as measured by cardiovascular magnetic resonance (CMR) imaging in adult Fontan subjects.

Methods

Adults with a dominant left ventricle post-Fontan palliation (lateral tunnel or extracardiac connections) and healthy controls matched by sex and age were studied. We evaluated vascular flows using phase-contrast CMR imaging during unassisted breathing, negative pressure ventilation (NPV) and biphasic ventilation (BPV). Measurements were made within target vessels (aorta, pulmonary arteries, vena cavae and Fontan circuit) at baseline and during each ventilation mode.

Results

Ten Fontan subjects (50% male, 24.5 years (IQR 20.8–34.0)) and 10 matched controls were studied. Changes in PBF and CO, respectively, were greater following BPV as compared with NPV. In subjects during NPV, PBF increased by 8% (Δ0.20 L/min/m² (0.10–0.53), p=0.011) while CO did not change significantly (Δ0.17 L/min/m² (−0.11–0.23), p=0.432); during BPV, PBF increased by 25% (Δ0.61 L/min/m² (0.20–0.84), p=0.002) and CO increased by 16% (Δ0.47 L/min/m² (0.21–0.71), p=0.010). Following BPV, change in PBF and CO were both significantly higher in subjects versus controls (0.61 L/min/m² (0.2–0.84) vs −0.27 L/min/m² (−0.55–0.13), p=0.001; and 0.47 L/min/m² (0.21–0.71) vs 0.07 L/min/m² (−0.47–0.33), p=0.034, respectively).

Conclusion

External ventilation acutely augments PBF and CO in adult Fontan subjects. Confirmation of these findings in larger populations with longer duration of ventilation and extended follow-up will be required to determine sustainability of haemodynamic effects.

Association of preoperative spirometry with cardiopulmonary fitness and postoperative outcomes in surgical patients: A multicentre prospective cohort study

BACKGROUND

Preoperative spirometry and cardiopulmonary exercise testing (CPET) may stratify risk for respiratory complications. This secondary analysis of the Measurement of Exercise Tolerance before Surgery (METS) study examined whether CPET performance (i.e., cardiopulmonary fitness) confounds associations of spirometry with outcomes.

METHODS

The analysis included 1200 participants having major non-cardiac surgery at 25 hospitals in Canada, Australia, New Zealand and UK. Forced expiratory volume in 1 s (FEV₁), and ratio of FEV₁ to forced vital capacity (FVC) were measured during preoperative spirometry, and peak oxygen consumption and ventilatory efficiency during preoperative CPET. Outcomes were respiratory morbidity (Postoperative Morbidity Survey) and pulmonary complications (pneumonia or respiratory failure). We used multivariable logistic regression models to estimate associations of FEV₁ with outcomes after adjustment for risk factors and either peak oxygen consumption or ventilatory efficiency.

FINDINGS

128 participants (11%) developed respiratory morbidity, and 48 (4%) developed pulmonary complications. There was no strong evidence that FEV₁ predicted respiratory morbidity after adjustment for peak oxygen consumption (p = 0·80) or ventilatory efficiency (p = 0·76), or FEV₁ predicted pulmonary complications after adjustment for ventilatory efficiency (p = 0·37). Peak oxygen consumption (odds ratio 0·66 per 5 mL/kg/min increase; 95% CI, 0·54-0·82) was associated with respiratory morbidity. Ventilatory efficiency was associated with respiratory morbidity (p = 0·04) and pulmonary complications (p = 0·02). Peak oxygen consumption also confounded the association between FEV₁ and respiratory morbidity.

INTERPRETATION

After accounting for fitness and clinical factors, FEV₁ was not strongly predictive of respiratory complications. Prior associations between FEV₁ and respiratory morbidity may be explained by confounding by peak oxygen consumption.

FUNDING

Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Ontario Ministry of Health and Long-Term Care, Ontario Ministry of Research, Innovation and Science, UK National Institute of Academic Anaesthesia, UK Clinical Research Collaboration, Australian and New Zealand College of Anaesthetists, and Monash University.

Pulmonary hypertension in patients with a subaortic right ventricle: prevalence, impact and management

Objective

This study sought to determine the prevalence, predictors, prognostic relevance and evolution of pulmonary hypertension (PH) (mean pulmonary artery pressure ≥25 mm Hg) in adult patients with a subaortic right ventricle (RV) in a biventricular circulation (2V-RV).

Methods

We analysed retrospective data from patients with 2V-RV undergoing cardiac catheterisation in our centre between 2000 and 2018. Echocardiographic assessment of subpulmonary ventricular pressures (left ventricular systolic pressure (LVSP)), age and B-type natriuretic peptide (BNP) were assessed as PH screening tools. Kaplan-Meier curves examined time to a composite outcome of death, transplant or ventricular assist device (VAD). Data from repeat catheterisations were analysed to evaluate PH changes over time, including the effects of therapy.

Results

A total of 141 patients (median age 39 (IQR 33–45) years, 68% men) underwent 191 cardiac catheterisations. At baseline, 55% had PH (isolated postcapillary 24%, combined precapillary and postcapillary 26% and precapillary 5%). BNP (area under the curve 0.80; 95% CI 0.72 to 0.88; p<0.0001), but not age at catheterisation or echocardiographic estimates of LVSP were associated with the presence of PH. The absence of PH and BNP <100 pg/mL discriminated a subgroup at very low risk during short-term (2.5 (1.3–3.9) years) follow-up (p<0.0001). Diuretics, milrinone and VAD improved haemodynamics over time.

Conclusion

PH is prevalent in patients with 2V-RV even when asymptomatic. It is difficult to identify by echocardiography and most importantly, is strongly associated with adverse outcomes. PH affects prognosis and transplant options for this patient group and yet is often amenable to treatment. Awareness of these results ought to lower the threshold for invasive haemodynamic assessment and may change the management of failing patients with 2V-RV.

Osteopontin lung gene expression is a marker of disease severity in pulmonary arterial hypertension

BACKGROUND AND OBJECTIVE

Osteopontin (OPN) is a pleiotropic cytokine involved in the proliferation of pulmonary artery smooth muscle cells (PA-SMC). OPN is upregulated in the lungs of patients with pulmonary hypertension (PH) associated with pulmonary fibrosis, suggesting that the lung is a source of OPN. We hypothesized that OPN lung expression is elevated in Group I pulmonary arterial hypertension (PAH) and is correlated to haemodynamics.

METHODS

Microarray analysis (Affymetrix) was performed after RNA was extracted from explanted lungs in 15 patients with Group I PAH who underwent lung transplantation (LTx) and 11 normal controls. PA pressure levels were recorded intraoperatively, immediately before starting LTx. Serum OPN levels were measured in subjects with PAH, Group II PH and normal controls on the day of right heart catheterization.

RESULTS

OPN was among the top five upregulated genes in PAH compared to normal controls, which was confirmed by reverse transcription polymerase chain reaction (RT-PCR). OPN expression was similar and equally elevated in different subtypes of PAH. A strong significant correlation was observed between mean pulmonary arterial pressure and OPN gene expression. Ingenuity pathway analysis showed the involvement of OPN in functions and networks relevant to angiogenesis, cell death and proliferation of PA-SMC. OPN serum levels did not differ in subjects with Group I PAH and Group II PH.

CONCLUSION

In the lungs of patients with severe PAH, OPN is highly expressed and the level of expression is significantly correlated to disease severity. OPN may play an important role in the vascular remodelling process of PAH.

Applied Bayesian Methods in the Rheumatic Diseases

The use of applied Bayesian methods is increasing in rheumatology. Using the Bayes theorem, past evidence is updated with new data. Preexisting data are expressed as a prior probability distribution or prior. New observations are expressed as a likelihood. Through explicit incorporation of preexisting data and new data, this process informs how this new information should change the way we think. In this article, the authors highlight the use of applied Bayesian methods in the study of rheumatic diseases.

Serial imaging after pulmonary embolism and correlation with functional limitation at 12 months: Results of the ELOPE Study

INTRODUCTION

Risk factors for exercise limitation after acute pulmonary embolism (PE) are unknown. As a planned sub-study of the prospective, multicenter ELOPE (Evaluation of Long-term Outcomes after PE) Study, we aimed to describe the results of serial imaging by computed tomography pulmonary angiography (CTPA) and perfusion scan during 1 year after a first episode of acute pulmonary embolism, and to assess the association between imaging parameters and exercise limitation at 1 year.

METHODS

In a prospective cohort study, 100 patients were recruited between June 2010 and February 2013 at five Canadian university-affiliated hospitals. CT pulmonary angiography was performed at baseline and 12 months, perfusion scan at 6 and 12 months, and cardio-pulmonary exercise testing at 1 and 12 months. Imaging parameters included: on CT pulmonary angiography, CT obstruction index (CTO) (% clot burden in the pulmonary vasculature), and on perfusion scan, pulmonary vascular obstruction (PVO) (% perfusion defect). Abnormal cardio-pulmonary exercise test (primary outcome) was defined as percent of predicted peak oxygen uptake (VO2) <80%.

RESULTS

Mean (median; SD) CT obstruction index was 28.1% (27.5%; 18.3%) at baseline, 1.2% (0%; 4.3%) at 12 months. Mean (median; SD) pulmonary vascular obstruction was 6.0% (0%; 9.6%) at 6 months, 5.6% (0%; 9.8%) at 12 months. Eighty-six patients had exercise testing at 12 months, and 46.5% had VO2 < 80% predicted. Mean (median; SD) CT obstruction index at 1 year was similar in patients with percent-predicted VO2 peak <80% vs >80% on 1-year cardio-pulmonary exercise testing (1.4% [0%; 5.7%] vs 1.0% [0%; 2.4%]; P = .70). Mean (SD) pulmonary vascular obstruction at 6 and at 12 months was similar in patients with percent-predicted VO2 peak <80% vs >80% (6 months: 5.9% [0%; 10.4%] vs 6.2% [4.5%; 9.0%]; P = .91; 12 months: 5.1% [0%; 10.2%] vs 6.0% [0%; 9.7%]; P = .71).

CONCLUSIONS

Imaging findings after pulmonary embolism did not predict exercise limitation. Residual thrombus does not appear to explain long-term functional limitation after pulmonary embolism.

Assessment of functional capacity before major non-cardiac surgery: an international, prospective cohort study

BACKGROUND

Functional capacity is an important component of risk assessment for major surgery. Doctors' clinical subjective assessment of patients' functional capacity has uncertain accuracy. We did a study to compare preoperative subjective assessment with alternative markers of fitness (cardiopulmonary exercise testing [CPET], scores on the Duke Activity Status Index [DASI] questionnaire, and serum N-terminal pro-B-type natriuretic peptide [NT pro-BNP] concentrations) for predicting death or complications after major elective non-cardiac surgery.

METHODS

We did a multicentre, international, prospective cohort study at 25 hospitals: five in Canada, seven in the UK, ten in Australia, and three in New Zealand. We recruited adults aged at least 40 years who were scheduled for major non-cardiac surgery and deemed to have one or more risk factors for cardiac complications (eg, a history of heart failure, stroke, or diabetes) or coronary artery disease. Functional capacity was subjectively assessed in units of metabolic equivalents of tasks by the responsible anaesthesiologists in the preoperative assessment clinic, graded as poor (<4), moderate (4-10), or good (>10). All participants also completed the DASI questionnaire, underwent CPET to measure peak oxygen consumption, and had blood tests for measurement of NT pro-BNP concentrations. After surgery, patients had daily electrocardiograms and blood tests to measure troponin and creatinine concentrations until the third postoperative day or hospital discharge. The primary outcome was death or myocardial infarction within 30 days after surgery, assessed in all participants who underwent both CPET and surgery. Prognostic accuracy was assessed using logistic regression, receiver-operating-characteristic curves, and net risk reclassification.

FINDINGS

Between March 1, 2013, and March 25, 2016, we included 1401 patients in the study. 28 (2%) of 1401 patients died or had a myocardial infarction within 30 days of surgery. Subjective assessment had 19·2% sensitivity (95% CI 14·2-25) and 94·7% specificity (93·2-95·9) for identifying the inability to attain four metabolic equivalents during CPET. Only DASI scores were associated with predicting the primary outcome (adjusted odds ratio 0·96, 95% CI 0·83-0·99; p=0·03).

INTERPRETATION

Subjectively assessed functional capacity should not be used for preoperative risk evaluation. Clinicians could instead consider a measure such as DASI for cardiac risk assessment.

FUNDING

Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Ontario Ministry of Health and Long-Term Care, Ontario Ministry of Research, Innovation and Science, UK National Institute of Academic Anaesthesia, UK Clinical Research Collaboration, Australian and New Zealand College of Anaesthetists, and Monash University.

Flow-related right ventricular to pulmonary arterial pressure gradients during exercise

Aims

The assumption of equivalence between right ventricular (RV) and pulmonary arterial systolic pressure is fundamental to several assessments of RV or pulmonary vascular haemodynamic function. Our aims were to (i) determine whether systolic pressure gradients develop across the RV outflow tract in healthy adults during exercise, (ii) examine the potential correlates of such gradients, and (iii) consider the effect of such gradients on calculated indices of RV function.

Methods and results

Healthy untrained and endurance-trained adult volunteers were studied using right-heart catheterization at rest and during submaximal cycle ergometry. RV and pulmonary artery (PA) pressures were simultaneously transduced, and the cardiac output was determined by thermodilution. Systolic pressures, peak and mean gradients, and indices of chamber, vascular, and valve function were analysed offline. Summary data are reported as mean ± standard deviation or median (interquartile range). No significant RV outflow tract gradients were observed at rest [mean gradient = 4 (3–5) mmHg], and the calculated effective orifice area was 3.6 ± 1.0 cm2. The increase in right ventricular systolic pressure during exercise was greater than the PA systolic pressure. Accordingly, mean gradients were developed during light exercise [8 (7–9) mmHg] and increased during moderate exercise [12 (9–14) mmHg, P < 0.001]. The magnitude of the mean gradient was linearly related to the cardiac output (r2 = 0.70, P < 0.001).

Conclusions

In healthy adults without pulmonic stenosis, systolic pressure gradients develop during exercise, and the magnitude is related to the blood flow rate.

Heparin-Induced Thrombocytopenia in the Critically Ill Patient

Heparin-induced thrombocytopenia (HIT) is associated with clinically significant morbidity and mortality. Patients who are critically ill are commonly thrombocytopenic and exposed to heparin. Although HIT should be considered, it is not usually the cause of thrombocytopenia in the medical-surgical ICU population. A systematic approach to the patient who is critically ill who has thrombocytopenia according to clinical features, complemented by appropriate laboratory confirmation, should lead to a reduction in inappropriate laboratory testing and reduce the use of more expensive and less reliable anticoagulants. If the patient is deemed as being at intermediate or high risk for HIT or if HIT is confirmed by means of the serotonin-release assay, heparin should be stopped, heparin-bonded catheters should be removed, and a direct antithrombin or fondaparinux should be initiated to reduce the risk of thrombosis. Warfarin is absolutely contraindicated in the acute phase of HIT; if administered, its effects must be reversed by using vitamin K.

The feasibility of assessing swallowing physiology following prolonged intubation after cardiovascular surgery

Background

Dysphagia following prolonged intubation after cardiovascular (CV) surgery is common occurring in 67% of patients; however, this population’s swallowing physiology has never been prospectively evaluated using standardized methods. Hence, prior to conducting a larger study, our primary objective was to determine the feasibility of assessing swallowing physiology using instrumentation and validated interpretation methods in cardiovascular surgical patients following prolonged intubation.

Method

From July to October 2011, we approached adults undergoing CV surgery at our institution who were intubated > 48 h. Those with a tracheostomy were excluded. Videofluoroscopic swallowing study (VFS) and nasendoscopy were completed within 48 h after extubation. Feasibility measurements included recruitment rate, patient participation, task completion durations, and the inter-rater reliability of VFS measures using the intraclass correlation coefficient (ICC). VFSs were interpreted using perceptual rating tools (Modified Barium Swallow Measurement Tool for Swallow Impairment™^© and Penetration Aspiration Scale) and objective displacement measurements (hyoid displacement and pharyngeal constriction ratio).

Results

Of the 39 patients intubated > 48 h, 16 met inclusion criteria with three enrolled and completing the VFS. All refused nasendoscopy. Across all VFSs, rating completion time ranged from 14.6 to 51.7 min per patient with ICCs for VFS scales ranging from 0.25 (95% CI − 0.10 to 0.59) to 0.99 (95% CI 0.98 to 0.99).

Conclusions

This study design was not feasible as recruitment was slow, few patients participated, and no patient agreed to all procedures. We discuss necessary methodological changes and lessons learned that would generalize to future research.

Quality of Life, Dyspnea, and Functional Exercise Capacity Following a First Episode of Pulmonary Embolism: Results of the ELOPE Cohort Study

BACKGROUND

We aimed to evaluate health-related quality of life (QOL), dyspnea, and functional exercise capacity during the year following the diagnosis of a first episode of pulmonary embolism.

METHODS

This was a prospective multicenter cohort study of 100 patients with acute pulmonary embolism recruited at 5 Canadian hospitals from 2010-2013. We measured the outcomes QOL (by Short-Form Health Survey-36 [SF-36] and Pulmonary Embolism Quality of Life [PEmb-QoL] measures), dyspnea (by the University of California San Diego Shortness of Breath Questionnaire [SOBQ]) and 6-minute walk distance at baseline and 1, 3, 6, and 12 months after acute pulmonary embolism. Computed tomography pulmonary angiography was performed at baseline, echocardiogram was performed within 10 days, and cardiopulmonary exercise testing was performed at 1 and 12 months. Predictors of change in QOL, dyspnea, and 6-minute walk distance were assessed by repeated-measures mixed-effects models analysis.

RESULTS

Mean age was 50.0 years; 57% were male and 80% were treated as outpatients. Mean scores for all outcomes improved during 1-year follow-up: from baseline to 12 months, mean SF-36 physical component score improved by 8.8 points, SF-36 mental component score by 5.3 points, PEmb-QoL by -32.1 points, and SOBQ by -16.3 points, and 6-minute walk distance improved by 40 m. Independent predictors of reduced improvement over time were female sex, higher body mass index, and percent-predicted VO₂ peak <80% on 1 month cardiopulmonary exercise test for all outcomes; prior lung disease and higher pulmonary artery systolic pressure on 10-day echocardiogram for the outcomes SF-36 physical component score and dyspnea score; and higher main pulmonary artery diameter on baseline computed tomography pulmonary angiography for the outcome PEmb-QoL score.

CONCLUSIONS

On average, QOL, dyspnea, and walking distance improve during the year after pulmonary embolism. However, a number of clinical and physiological predictors of reduced improvement over time were identified, most notably female sex, higher body mass index, and exercise limitation on 1-month cardiopulmonary exercise test. Our results provide new information on patient-relevant prognosis after pulmonary embolism.

Exhaled Nitric Oxide in Systemic Sclerosis Lung Disease

Background. Exhaled nitric oxide (eNO) is a potential biomarker to distinguish systemic sclerosis (SSc) associated pulmonary arterial hypertension (PAH) and interstitial lung disease (ILD). We evaluated the discriminative validity, feasibility, methods of eNO measurement, and magnitude of differences across lung diseases, disease-subsets (SSc, systemic lupus erythematosus), and healthy-controls. Methods. Consecutive subjects in the UHN Pulmonary Hypertension Programme were recruited. Exhaled nitric oxide was measured at 50 mL/s intervals using chemiluminescent detection. Alveolar and conducting airway NO were partitioned using a two-compartment model of axial diffusion (CMAD) and the trumpet model of axial diffusion (TMAD). Results. Sixty subjects were evaluated. Using the CMAD model, control subjects had lower median (IQR) alveolar NO than all PAH subjects (2.0 (1.5, 2.5) versus 3.14 ppb (2.3, 4.0), p = 0.008). SSc-ILD had significantly lower median conducting airway NO compared to controls (1009.5 versus 1342.1 ml⁎ppb/s, p = 0.04). SSc-PAH had increased median (IQR) alveolar NO compared to controls (3.3 (3.0, 5.7) versus 2.0 ppb (1.5, 2.5), p = 0.01). SSc-PAH conducting airway NO inversely correlated with DLCO (r -0.88 (95% CI -0.99, -0.26)). Conclusion. We have demonstrated feasibility, identified that CMAD modeling is preferred in SSc, and reported the magnitude of differences across cases and controls. Our data supports discriminative validity of eNO in SSc lung disease.

The relationship of pulmonary vascular resistance and compliance to pulmonary artery wedge pressure during submaximal exercise in healthy older adults

KEY POINTS

A consistent inverse hyperbolic relationship has been observed between pulmonary vascular resistance and compliance, although changes in pulmonary artery wedge pressure (PAWP) may modify this relationship. This relationship predicts that pulmonary artery systolic, diastolic and mean pressure maintain a consistent relationship relative to the PAWP. We show that, in healthy exercising human adults, both pulmonary vascular resistance and compliance decrease in relation to exercise-associated increases in PAWP. Pulmonary artery systolic, diastolic and mean pressures maintain a consistent relationship with one another, increasing linearly with increasing PAWP. Increases in PAWP in the setting of exercise are directly related to a decrease in pulmonary vascular compliance, despite small decreases in pulmonary vascular resistance, thereby increasing the pulsatile afterload to the right ventricle.

ABSTRACT

The resistive and pulsatile components of right ventricular afterload (pulmonary vascular resistance, Rp; compliance, Cp) are related by an inverse hyperbolic function, expressed as their product known as RpCp-time. The RpCp-time exhibits a narrow range, although it may be altered by the pulmonary artery wedge pressure (PAWP). Identifying the determinants of RpCp-time should improve our understanding of the physiological behaviour of pulmonary arterial systolic (PASP), diastolic (PADP) and mean (mPAP) pressures in response to perturbations. We examined the effect of exercise in 28 healthy non-athletic adults (55 ± 6 years) who underwent right heart catheterization to assess haemodynamics and calculate Rp and Cp. Measurements were made at rest and during two consecutive 8-10 min stages of cycle ergometry, at targeted heart-rates of 100 beats min(-1) (Light) and 120 beats min(-1) (Moderate). Cardiac output increased progressively during exercise. PASP, PADP, mPAP and PAWP increased for Light exercise, without any further rise for Moderate exercise. RpCp-time decreased for Light exercise (0.39 ± 0.08 to 0.25 ± 0.08, P < 0.001) without any further change for Moderate exercise, and the decrease in RpCp-time was related to changes in PAWP (r(2)  = 0.26, P < 0.001). Changes in PASP (r(2)  = 0.43, P < 0.001), PADP (r(2)  = 0.47, P < 0.001) and mPAP (r(2)  = 0.50, P < 0.001) were linearly correlated with changes in PAWP, although they were not significantly related to changes in cardiac output. In healthy adults, exercise is associated with decreases in Cp and a resultant decline in RpCp-time, indicating increased pulsatile right ventricular afterload. Changes in RpCp-time, PASP, PADP and mPAP were systematically related to increases in PAWP.

Measurement of Exercise Tolerance before Surgery (METS) study: a protocol for an international multicentre prospective cohort study of cardiopulmonary exercise testing prior to major non-cardiac surgery

INTRODUCTION

Preoperative functional capacity is considered an important risk factor for cardiovascular and other complications of major non-cardiac surgery. Nonetheless, the usual approach for estimating preoperative functional capacity, namely doctors' subjective assessment, may not accurately predict postoperative morbidity or mortality. 3 possible alternatives are cardiopulmonary exercise testing; the Duke Activity Status Index, a standardised questionnaire for estimating functional capacity; and the serum concentration of N-terminal pro-B-type natriuretic peptide (NT pro-BNP), a biomarker for heart failure and cardiac ischaemia.

METHODS AND ANALYSIS

The Measurement of Exercise Tolerance before Surgery (METS) Study is a multicentre prospective cohort study of patients undergoing major elective non-cardiac surgery at 25 participating study sites in Australia, Canada, New Zealand and the UK. We aim to recruit 1723 participants. Prior to surgery, participants undergo symptom-limited cardiopulmonary exercise testing on a cycle ergometer, complete the Duke Activity Status Index questionnaire, undergo blood sampling to measure serum NT pro-BNP concentration and have their functional capacity subjectively assessed by their responsible doctors. Participants are followed for 1 year after surgery to assess vital status, postoperative complications and general health utilities. The primary outcome is all-cause death or non-fatal myocardial infarction within 30 days after surgery, and the secondary outcome is all-cause death within 1 year after surgery. Both receiver-operating-characteristic curve methods and risk reclassification table methods will be used to compare the prognostic accuracy of preoperative subjective assessment, peak oxygen consumption during cardiopulmonary exercise testing, Duke Activity Status Index scores and serum NT pro-BNP concentration.

ETHICS AND DISSEMINATION

The METS Study has received research ethics board approval at all sites. Participant recruitment began in March 2013, and 1-year follow-up is expected to finish in 2016. Publication of the results of the METS Study is anticipated to occur in 2017.

Sex disparities in systemic sclerosis-associated pulmonary arterial hypertension: a cohort study

Background

The impact of male sex as a determinant of health outcomes in systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) is controversial. The primary objective of this study was to evaluate the effect of sex on survival in patients with SSc-PAH. The secondary objectives were to evaluate the effect of sex on age of PAH diagnosis, time from SSc diagnosis to PAH diagnosis, and SSc disease manifestations.

Methods

Sex-based disparities were evaluated in a cohort of SSc-PAH patients with a primary outcome of time from PAH diagnosis to all-cause mortality. Secondary outcomes were differences in age of diagnosis, disease duration, and SSc manifestations. Survival differences were evaluated using Kaplan-Meier and Cox proportional hazard models.

Results

We identified 378 SSc-PAH (58 males, 320 females) patients, with a female:male ratio of 5.5:1. Males had a shorter mean ± standard deviation time from SSc diagnosis to PAH diagnosis (1.7 ± 14 versus 5.5 ± 14.2 years); shorter PAH duration (3.5 ± 3.1 versus 4.7 ± 4.2 years), increased frequency of renal crisis (19 % versus 8 %, relative risk (RR) 2.33, 95 %CI 1.22, 4.46), interstitial lung disease (67 % versus 48 %, RR 1.41, 95 %CI 1.14, 1.74), and diffuse subtype (40 % versus 22 %, RR 1.84, 95 %CI 1.26, 2.69). Males appeared to have decreased 1-, 2-, 3-, and 5-year survival (83.2 %, 68.7 %, 53.2 %, 45.6 %) compared to females (85.7 %, 75.7 %, 66.4 %, 57.4 %). However, there was no difference in mortality between sexes (HR 1.43 (95 %CI 0.97, 2.13).

Conclusions

Sex disparities appear to exist in the frequency of PAH, time to PAH diagnosis, PAH disease duration and SSc disease burden. However, male sex does not independently impact SSc-PAH survival.

The pulmonary artery wedge pressure response to sustained exercise is time-variant in healthy adults

OBJECTIVES

The clinical and prognostic significance of 'exaggerated' elevations in pulmonary artery wedge pressure (PAWP) during symptom-limited exercise testing is increasingly recognised. However, the paucity of normative data makes the identification of abnormal responses challenging. Our objectives was to describe haemodynamic responses that reflect normal adaptation to submaximal exercise in a group of community-dwelling, older, non-dyspnoeic adults.

METHODS

Twenty-eight healthy volunteers (16 men/12 women; 55±6 years) were studied during rest and two consecutive stages of cycle ergometry, at targeted heart rates of 100 bpm (light exercise) and 120 bpm (moderate exercise). Right-heart catheterisation was performed to measure pulmonary artery pressures, both early (2 min) and after sustained (7 min) exercise at each intensity.

RESULTS

End-expiratory PAWP at baseline was 11±3 mm Hg and increased to 22±5 mm Hg at early-light exercise (p<0.01). At sustained-light exercise, PAWP declined to 17±5 mm Hg, remaining elevated versus baseline (p<0.01). PAWP increased again at early-moderate exercise to 20±6 mm Hg but did not exceed the values observed at early-light exercise, and declined further to 15±5 mm Hg at sustained-moderate exercise (p<0.01 vs baseline). When analysed at 30 s intervals, mean and diastolic pulmonary artery pressures peaked at 180 (IQR=30) s and 130 (IQR=90) s, respectively, and both declined significantly by 420 (IQR=30) s (both p<0.01) of light exercise. Similar temporal patterns were observed at moderate exercise.

CONCLUSIONS

The range of PAWP responses to submaximal exercise is broad in health, but also time-variant. PAWP may routinely exceed 20 mm Hg early in exercise. Initial increases in PAWP and mean pulmonary artery pressures do not necessarily reflect abnormal cardiopulmonary physiology, as pressures may normalise within a period of minutes.

Survival in rheumatoid arthritis-associated pulmonary arterial hypertension compared with idiopathic pulmonary arterial hypertension

BACKGROUND AND OBJECTIVE

In this study, we evaluated survival in rheumatoid arthritis-associated pulmonary arterial hypertension (RA-PAH) compared with idiopathic pulmonary arterial hypertension (IPAH) patients, and evaluate differences in disease severity and treatment.

METHODS

We conducted a retrospective cohort study of RA-PAH and IPAH at the University Health Network Pulmonary Hypertension Programme, Toronto, Canada. The primary outcome was time to all-cause mortality. We evaluated survival using Kaplan-Meier curves. Using a propensity score-matched cohort, we used Cox proportional hazards models to estimate survival.

RESULTS

Screening 1385 patients identified 18 RA-PAH and 155 IPAH patients. RA-PAH patients had an older median age of onset (64.0 vs 53.7 years) and lower baseline mean pulmonary arterial pressure (mPAP) (41 vs 50 mm Hg, P = 0.02). RA-PAH patients tended to have a higher proportion of females (83% vs 70%, relative risk 0.55, 95% confidence interval (CI): 0.19-1.57), lower proportion with baseline World Health Organization functional class III/IV (39% vs 52%), lower median baseline brain natriuretic peptide (58.4 vs 95.0 pg/mL) and longer baseline 6-min walk distance (440 vs 397 m). There were 35 deaths, 2/18 (11%) RA-PAH patients and 33/155 (21%) IPAH patients. The unadjusted 1-year survival was 93% for RA-PAH and 94% for IPAH. In the matched cohort, there were seven deaths: 2/18 (11%) RA-PAH and 5/18 (28%) IPAH patients, hazard ratio 1.53 (95% CI: 0.15-2.84). Separation of survival curves did not achieve statistical significance, log-rank 0.56.

CONCLUSIONS

Compared with IPAH patients, RA-PAH patients have an older age of onset and lower baseline mPAP. RA-PAH patients have comparable survival to IPAH patients.

Oxygenation response to positive end-expiratory pressure predicts mortality in acute respiratory distress syndrome. A secondary analysis of the LOVS and ExPress trials

RATIONALE

Previous trials of higher positive end-expiratory pressure (PEEP) for acute respiratory distress syndrome (ARDS) failed to demonstrate mortality benefit, possibly because of differences in lung recruitability among patients with ARDS.

OBJECTIVES

To determine whether the physiological response to increased PEEP is associated with mortality.

METHODS

In a secondary analysis of the Lung Open Ventilation Study (LOVS, n = 983), we examined the relationship between the initial response to changes in PEEP after randomization and mortality. We sought to corroborate our findings using data from a different trial of higher PEEP (ExPress, n = 749).

MEASUREMENTS AND MAIN RESULTS

The oxygenation response (change in ratio of arterial partial pressure of oxygen to fraction of inspired oxygen: P/F) after the initial change in PEEP after randomization varied widely (median, 9.5 mm Hg; interquartile range, -16 to 47) and was only weakly related to baseline P/F or the magnitude of PEEP change. Among patients in whom PEEP was increased after randomization, an increase in P/F was associated with reduced mortality (multivariable logistic regression; adjusted odds ratio, 0.80 [95% confidence interval, 0.72-0.89] per 25-mm Hg increase in P/F), particularly in patients with severe disease (baseline P/F [less-than-or-equal-to] 150 mm Hg). Changes in compliance and dead space were not associated with mortality. These findings were confirmed by a similar analysis of data from the ExPress trial.

CONCLUSIONS

Patients with ARDS who respond to increased PEEP by improved oxygenation have a lower risk of death. The oxygenation response to PEEP might be used to predict whether patients will benefit from higher versus lower PEEP.

Sleep disordered breathing in group 1 pulmonary arterial hypertension

STUDY OBJECTIVES

To determine the prevalence and clinical predictors of sleep disordered breathing (SDB) and impact on outcomes in a cohort of patients with WHO group 1 pulmonary arterial hypertension (PAH).

METHODS

A retrospective, cross-sectional review of 52 consecutive subjects with known WHO group 1 PAH referred for assessment of possible SDB. Subjects had overnight polysomnography within 6 months of right heart catheterization performed as part of a routine clinical protocol.

RESULTS

SDB was present in 71% of the PAH patients: 56% had OSA and 44% CSA. Older age and subjective sleepiness as assessed by the Epworth Sleepiness Scale score > 10 were predictive of SDB. A high prevalence of OSA occurred in both male (50%) and female (60%) subjects. No differences in cardiopulmonary hemodynamics or survival between those with and without SDB were observed.

CONCLUSIONS

This high prevalence of SDB in the PAH population suggests that systematic screening and testing is important in this group. Further studies are necessary to determine the pathophysiological effect of SDB and potential impact of SDB treatment in this population.

CITATION

Minic M; Granton JT; Ryan CM. Sleep disordered breathing in group 1 pulmonary arterial hypertension.

Survival after lung transplantation in systemic sclerosis. A systematic review

BACKGROUND

Lung transplantation is a life-saving option for systemic sclerosis (SSc)-associated pulmonary arterial hypertension (PAH) and interstitial lung disease (SSc-ILD) patients. However, some programs may be concerned about the possibility of excess post-transplantation mortality related to the extra-pulmonary manifestations of SSc. The objective of this study was to evaluate survival of SSc patients post-lung transplantation. We secondarily evaluated SSc lung transplant recipient characteristics (age, sex, and type of SSc lung disease), and discussed post-lung transplantation survival of SSc patients and non-SSc patients (idiopathic PAH, and ILD).

METHODS

A systematic review of MEDLINE, EMBASE, Cochrane Central Registry of Controlled Trials and CINAHL (all inception to 2012) was performed to identify studies evaluating post-lung transplant survival in SSc compared to PAH and ILD patients. Two reviewers independently abstracted study and survival data.

RESULTS

Two hundred twenty-six citations were screened to identify 7 observational studies reporting SSc patients who underwent single lung, double lung, or heart-lung transplantation. Mean age at transplantation ranged 46-53 years. SSc post-transplantation survival ranged 69%-91% at 30-days, 69%-85% at 6-months, 59%-93% at 1-year, 49%-80% at 2-years, and 46%-79% at 3-years. Causes of death included graft failure, infection, cardiac events, hemorrhagic stroke, respiratory failure, malignancy, pulmonary hypertension, complications of bronchiolitis obliterans syndrome, anesthetic complication, and scleroderma renal crisis. There were no reports of recurrence of SSc in the lung allograft.

CONCLUSION

The short-term and intermediate-term survival post-lung transplantation are similar to IPAH and ILD patients requiring lung transplantation.

High-frequency oscillation in early acute respiratory distress syndrome

BACKGROUND

Previous trials suggesting that high-frequency oscillatory ventilation (HFOV) reduced mortality among adults with the acute respiratory distress syndrome (ARDS) were limited by the use of outdated comparator ventilation strategies and small sample sizes.

METHODS

In a multicenter, randomized, controlled trial conducted at 39 intensive care units in five countries, we randomly assigned adults with new-onset, moderate-to-severe ARDS to HFOV targeting lung recruitment or to a control ventilation strategy targeting lung recruitment with the use of low tidal volumes and high positive end-expiratory pressure. The primary outcome was the rate of in-hospital death from any cause.

RESULTS

On the recommendation of the data monitoring committee, we stopped the trial after 548 of a planned 1200 patients had undergone randomization. The two study groups were well matched at baseline. The HFOV group underwent HFOV for a median of 3 days (interquartile range, 2 to 8); in addition, 34 of 273 patients (12%) in the control group received HFOV for refractory hypoxemia. In-hospital mortality was 47% in the HFOV group, as compared with 35% in the control group (relative risk of death with HFOV, 1.33; 95% confidence interval, 1.09 to 1.64; P=0.005). This finding was independent of baseline abnormalities in oxygenation or respiratory compliance. Patients in the HFOV group received higher doses of midazolam than did patients in the control group (199 mg per day [interquartile range, 100 to 382] vs. 141 mg per day [interquartile range, 68 to 240], P<0.001), and more patients in the HFOV group than in the control group received neuromuscular blockers (83% vs. 68%, P<0.001). In addition, more patients in the HFOV group received vasoactive drugs (91% vs. 84%, P=0.01) and received them for a longer period than did patients in the control group (5 days vs. 3 days, P=0.01).

CONCLUSIONS

In adults with moderate-to-severe ARDS, early application of HFOV, as compared with a ventilation strategy of low tidal volume and high positive end-expiratory pressure, does not reduce, and may increase, in-hospital mortality. (Funded by the Canadian Institutes of Health Research; Current Controlled Trials numbers, ISRCTN42992782 and ISRCTN87124254, and ClinicalTrials.gov numbers, NCT00474656 and NCT01506401.).

Haemodynamic and structural correlates of the first and second heart sounds in pulmonary arterial hypertension: an acoustic cardiography cohort study

OBJECTIVE

To examine the relationship between acoustic characteristics of the first and second heart sounds (S1 and S2) and underlying cardiac structure and haemodynamics in patients with isolated pulmonary arterial hypertension (PAH) and controls.

DESIGN

Prospective multicentre cohort study.

SETTING

Tertiary referral and community hospitals.

PARTICIPANTS

We prospectively evaluated 40 PAH patients undergoing right-heart catheterisation with contemporaneous digital acoustic cardiography (intensity and complexity) and two-dimensional transthoracic echocardiography. To normalise for differences in body habitus, acoustic variables were also expressed as a ratio (S2/S1). 130 participants (55 also had haemodynamic and/or echocardiographic assessment) without clinical or haemodynamic evidence of PAH or congestive heart failure acted as controls.

RESULTS

Patients with PAH had higher mean pulmonary artery pressure (mPA; 40±13 vs 16±4 mm Hg, p<0.0001) and pulmonary vascular resistance (9±6 vs 1±1 Wood Units, p<0.0001) compared with controls, but cardiac index and mean pulmonary capillary wedge pressure were similar. More PAH patients had evidence of right ventricular (RV) dilation (50% vs 19%) and RV systolic dysfunction (41% vs 9%) in the moderate-severe range (all p<0.05). Compared with controls, the acoustic profiles of PAH patients were characterised by increased S2 complexity, S2/S1 complexity and S2/S1 intensity (all p<0.05). In the PAH cohort, S2 complexity was inversely related to S1 complexity. mPA was the only independent multivariate predictor of S2 complexity. The severity of RV enlargement and systolic impairment had reciprocal effects on the complexity of S2 (increased) and S1 (decreased). Decreased S1 complexity was also related to evidence of a small left ventricular cavity.

CONCLUSIONS

Acoustic characteristics of both S1 and S2 are related to the severity of PAH and are associated with RV enlargement and systolic dysfunction. The reciprocal relationship between S2 and S1 complexity may also reflect the underlying ventricular interaction associated with PAH.

The effect of endogenous estrogen on Doppler-estimated right ventricular systolic pressure during exercise

We evaluated the effect of endogenous estrogen levels on exercise-related changes in right ventricular systolic pressure (RVSP) of healthy, eumenorrheic, sedentary women. Volunteers were studied at two separates phases of the menstrual cycle (LO and HI estrogen phases), exercised on a semi-supine ergometer with escalating workload and monitored continuously by 12-lead ECG and automated blood pressure cuff. At each exercise stage, Doppler echocardiography measurements were obtained and analyzed to determine RVSP. Fourteen subjects (age 24 ± 5) were studied. Exercise duration was significantly higher on the HI estrogen day, but no significant differences in hemodynamic response to exercise were found between the two study days. There were also no significant differences with respect to heart rate (HR) acceleration during early exercise, as well as resting and peak RVSP, HR, blood pressure, and rate pressure product. Doppler-estimated RVSP demonstrated a linear relationship to HR at a ratio of 1 mm Hg (1 mm Hg = 133.3224 Pa) for every 5 bpm (beats per minute) increase in HR. There were no differences in the slope of this relationship between HI and LO estrogen phases of the menstrual cycle. Our findings did not demonstrate any effect of endogenous estrogen levels on the modulation of the pulmonary vascular response to exercise in healthy women.

Dual therapy in IPAH and SSc-PAH. A qualitative systematic review

BACKGROUND

Use of endothelin receptor antagonists (ERA), phosphodiesterase type-5 (PDE-5) inhibitors and prostaglandin analogues has resulted in improved outcomes in idiopathic pulmonary arterial hypertension (IPAH) and systemic sclerosis-associated PAH (SSc-PAH) patients. However, patients often deteriorate on monotherapy. The objective of this study is to evaluate the effect of dual therapy on outcomes in IPAH and SSc-PAH.

METHODS

A systematic review of MEDLINE (1950-2011), EMBASE (1980-2011) and CINAHL (inception-2011) was conducted to identify studies that evaluated the effect of any dual combination of ERA, PDE-5 inhibitors or prostaglandin analogues on 6-min walk distance (6MWD), functional class (FC), haemodynamics, quality-of-life (QoL) or time-to-clinical-worsening in IPAH or SSc-PAH. A standardized form was used to abstract design, sample size, aetiology, outcome and treatment effect.

RESULTS

Twenty-six observational studies and 6 randomized trials were identified. Using combination PDE-5 inhibitor and prostaglandin analogues, 6/7 studies reported improvement in 6MWD, 6/8 studies reported improvement in FC, 6/6 studies reported improvement in haemodynamics and 1 trial demonstrated improvement in QoL and time-to-clinical-worsening. Using combination ERA and prostaglandin analogues, 4/6 studies and 1 trial reported improvement in 6MWD, 3/3 studies and 1 trial reported improvement in FC, 4/5 studies and 1 trial reported improvement in PAP. Using combination ERA and PDE-5 inhibitor, 4/7 studies reported an improvement in 6MWD, and 2/6 report improvement in FC.

CONCLUSION

The evidence suggests a beneficial effect of dual therapy in IPAH and SSc-PAH, particularly those who are deteriorating on monotherapy. Research should focus on subsets of patients to identify the optimal timing and combination of dual therapy.

Warfarin in systemic sclerosis-associated and idiopathic pulmonary arterial hypertension. A Bayesian approach to evaluating treatment for uncommon disease

OBJECTIVE

Warfarin is recommended in systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) and idiopathic PAH (IPAH) to improve survival. There is no evidence to support this in SSc-PAH and the evidence in IPAH is conflicting. We evaluated the ability of warfarin to improve survival using 2 large SSc-PAH and IPAH cohorts.

METHODS

The effect of warfarin on all-cause mortality was evaluated. Bayesian propensity scores (PS) were used to adjust for baseline differences between patients exposed and not exposed to warfarin, and to assemble a matched cohort. Bayesian Cox proportional hazards models were constructed using informative priors based on international PAH expert elicitation.

RESULTS

Review of 1138 charts identified 275 patients with SSc-PAH (n = 78; 28% treated with warfarin) and 155 patients with IPAH (n = 91; 59% treated with warfarin). Baseline differences in PAH severity and medications were resolved using PS matching. In the matched cohort of 98 patients with SSc-PAH (49 treated with warfarin), the posterior median hazard ratio (HR) was 1.06 [95% credible interval (CrI) 0.70, 1.63]. In the matched cohort of 66 patients with IPAH (33 treated with warfarin), the posterior median HR was 1.07 (95% CrI 0.57, 1.98). The probability that warfarin improves median survival by 6 months or more is 23.5% in SSc-PAH and 27.7% in IPAH. Conversely, there is a > 70% probability that warfarin provides no significant benefit or is harmful.

CONCLUSION

There is a low probability that warfarin improves survival in SSc-PAH and IPAH. Given the availability of other PAH therapies with demonstrable benefits, there is little reason to use warfarin to improve survival for these patients.

Examining nursing vital signs documentation workflow: barriers and opportunities in general internal medicine units

AIMS

To characterise the nursing practices of vital signs collection and documentation in a general internal medicine environment to inform strategies for improving workflow design.

BACKGROUND

Clinical workflow analysis is critical to identify barriers and opportunities in current processes. Analysis can guide the design and development of novel technological solutions to produce greater efficiencies and effectiveness in healthcare delivery. Research surrounding vital signs documentation workflow in general internal medicine environments has received very little attention making it difficult to compare the effectiveness of new technologies.

DESIGN

Qualitative ethnographic analyses and quantitative time-motion study were conducted.

METHODS

Workflows of 24 nurses at three hospitals in five general internal medicine environments were captured, and timeliness of vital signs assessment and documentation was measured.

RESULTS

Clinical assessment of vital signs was consistent, but the documentation process was highly variable within groups and between hospitals. Two themes characterised workflow barriers surrounding point-of-care documentation. First, a lack of standardised documentation methods for vital signs resulted in higher rates of transcription, increasing not only the likelihood of errors but delays in recording and accessibility of information. Second, despite advancements in electronic documentation systems, the observed system was not conducive to point-of-care documentation. Average electronic documentation was significantly longer than paper documentation. Nurses developed ad hoc workarounds that were inefficient and undermined the intent of electronic documentation.

CONCLUSION

We have identified barriers and opportunities to improve the efficiency of nursing vital signs documentation. Changes in technology, workflows and environmental design allow for significant improvements and deserve further exploration.

RELEVANCE TO CLINICAL PRACTICE

Attention to clinical practice and environments can improve the workflow of prompt vital signs documentation and increase clinical productivity and timeliness of information for clinical decisions, as well as minimising transcription errors leading to safer patient care.

Right heart characteristics and exercise parameters in adults with Ebstein anomaly: new perspectives from cardiac magnetic resonance imaging studies

BACKGROUND

The utility of cardiac magnetic resonance imaging (CMR) for assessment of adults with Ebstein anomaly is not well-defined. We sought to evaluate CMR characteristics in this population and to relate these to exercise parameters.

METHODS

We analyzed CMR studies in adults with unrepaired Ebstein anomaly for measures of severity of Ebstein disease, including atrialized, functional and total right ventricular (RV) volumes, ejection fraction (EF) and severity index (area of atrialized RV+right atrium/functional RV+left ventricle+left atrium). We related these CMR values to cardiopulmonary exercise test measurements.

RESULTS

Twenty-seven adults (mean age 41 ± 14 years, 70% female) were included. Functional RV end-diastolic volume (EDV) was 150 ± 68 mL/m(2) and atrialized RVEDV was 25 ± 24 mL/m(2). In 17 patients (63%), the functional RVEDV was enlarged (>114 mL/m(2)). Percent predicted peak VO2 for the population was 65 ± 20%. On univariable analysis, peak VO2 was inversely related to atrialized RVEDV (p = 0.011), total RVEDV (p = 0.041), functional RVEDV/left ventricular EDV ratio (p = 0.015) and magnitude of tricuspid valve displacement (p = 0.031). In the multivariate model, the only CMR factor to relate to peak VO2 was atrialized RVEDV (p = 0.011, β = -0.48). No significant correlations were found between CMR measures and heart rate response or ventilatory response to exercise.

CONCLUSION

In adults with unrepaired Ebstein anomaly, atrialized RV volume was independently related to aerobic capacity. The volume of the atrialized RV is a novel CMR measure which may express severity of disease. Further research is needed to evaluate the prognostic relevance of this exploratory work.