Use of exercise tests in screening for pulmonary arterial hypertension in systemic sclerosis: A systematic literature review

Background and objective

Patients with systemic sclerosis (SSc) and pulmonary arterial hypertension (PAH) have a poor prognosis, accounting for 30% of all SSc-related deaths. Guidelines recommend annual screening for PAH regardless of symptoms, as early treatment improves outcomes. Current protocols include combinations of clinical features, biomarkers, pulmonary function tests, and echocardiography. None include exercise testing, although early-stage PAH may only be evident during exercise. This systematic review assessed the performance of exercise tests in predicting the presence of PAH in patients with SSc, where PAH was confirmed through right heart catheterisation (RHC).

Methods

Comprehensive literature searches were performed using MEDLINE, EMBASE, Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trails, CINAHL, Scopus and Web of Science from inception to May 2023. Articles were screened for eligibility by two independent reviewers. Eligibility criteria included the use of a non-invasive exercise test to screen adult patients to detect PAH in a population without a previous diagnosis of PAH, with diagnosis confirmed by RHC.

Results

Eight studies met the inclusion criteria, describing at least one of three different non-invasive exercise tests: cardiopulmonary exercise test, six-minute walk test and stress Doppler echocardiography. All studies found that exercise tests had some ability to predict the presence of PAH, with sensitivity between 50% and 100% and specificity from 73% to 91%.

Conclusion

Exercise tests are infrequently used for screening for PAH in SSc but can predict the presence of PAH. More data are required to establish which tests are most effective.

Association of physiological reserve measures with adverse outcomes following liver transplantation

Background and Aim

The comparative utility of physiological reserve measures in predicting important clinical outcomes following liver transplantation (LT) requires further study. The aim of this work was therefore to compare the utility of physiological reserve measures in predicting early adverse clinical outcomes post‐LT.

Methods

A single‐center, retrospective cohort study of LT patients consecutively recruited between 1 January 2015, and 31 August 2020. Outcomes measured were sepsis and death within 12 months of LT, hospital length of stay (LOS), and intensive care LOS. Physiological reserve measures were handgrip strength, mid‐arm muscle circumference, and cardiopulmonary exercise testing (CPET) measures. Analysis was performed using univariate and multivariate logistic regression for sepsis and death, and univariate and multivariate Cox regression for hospital and intensive care LOS.

Results

Data were obtained for 109 subjects. Patients were predominantly (64%) male with a median (interquartile range [IQR]) age of 57 (49–63) and median (IQR) Model for End‐Stage Liver Disease score of 16 (11–21). In multivariate analysis, the odds of sepsis were lower in patients in the highest versus lowest tertile (odds ratio = 0.004; 95% confidence interval [CI] 0.00–0.13; P = 0.002). Hospital LOS was linearly associated with handgrip strength (hazard ratio [HR] = 1.03; 95% CI 1.00–1.06; P = 0.03) in multivariate analysis. Intensive care LOS was associated with peak VO₂ (HR 1.83; 95% CI 1.06–3.16; P = 0.03) and V_E/VCO₂ slope (HR 0.71; 95% CI 0.58–0.88; P = 0.002) in multivariate analysis.

Conclusion

Handgrip strength and CPET both identify candidates at high risk of adverse outcomes after LT.

Bolus intravenous 0.9% saline leads to interstitial permeability pulmonary edema in healthy volunteers

PURPOSE

Bolus intravenous administration of 0.9% saline has been associated with the development of pulmonary edema, and increased mortality. An animal model has previously demonstrated that rapid intravenous administration of 0.9% saline was associated with non-hydrostatic lung injury with increased lung lavage protein. We hypothesized that this non-hydrostatic effect would also occur in human volunteers.

METHODS

In a randomized, cross-over study of 14 healthy male subjects, the lung lavage protein concentration and cardiorespiratory effects of an intervention with rapid intravenous administration of 30 mL/kg of 0.9% saline were compared with sham intervention. Bronchoalveolar lavage (BAL) was performed after fluid administration. Doppler echocardiography, lung ultrasound, pulmonary function tests, and blood sampling were performed before and after each intervention.

RESULTS

The BAL total protein concentration was greater after 0.9% saline administration than with sham (196.1 µg/mL (SD 87.6) versus 129.8 µg/mL (SD 55.4), respectively (p = 0.020). Plasma angiopoietin-2 concentration was also increased to 2.26 ng/mL (SD 0.87) after 0.9% saline administration compared with sham 1.53 ng/mL (SD 0.69) (p < 0.001). There were small increases in stroke volume (from 58 mL (IQR 51-74) to 66 mL (IQR 58-74), p = 0.045) and Doppler echocardiography left ventricle E/e' ratio (from 5.0 (IQR 4.5-6.0) to 5.7 (IQR 5.3-6.3), p = 0.007), but no changes to right ventricular function.

CONCLUSION

Rapid intravenous administration of 0.9% saline leads to interstitial permeability pulmonary edema in healthy human volunteers. Further research is now warranted to understand these effects in critically ill patients.

Effects of the Spirometry Learning Module on the knowledge, confidence, and experience of spirometry operators

Our study measures effects of the Spirometry Learning Module (SLM) on health-care professionals' knowledge of spirometry test quality and perceived confidence, experience, and understanding of spirometry measurements and interpretation. Professionals from both primary and hospital-based settings enrolled in the SLM, a training model focusing on spirometry test performance and interpretation, including an online interactive learning component and a face-to-face workshop. Participants were asked to submit patient spirometry assessment worksheets for feedback on quality and interpretation. Data were collected at baseline, SLM completion (20 weeks), and 12 months after SLM completion. Knowledge of spirometry test quality was evaluated with questions relating to five case-based assessments of common spirometric patterns. Perceived confidence, experience, and knowledge in test performance were measured using a 7-point Likert scale. The Friedman test combined with post hoc analyses were used to analyse differences between baseline, 20-week, and 12-month post completion. Qualitative interviews were performed to assess reasons for non-completion. Of the 90 participants enrolled in the SLM and consented to research, 48 completed the 20-week measurement and 11 completed the 12-month measurement. Statistically significant improvements were detected in all outcomes in participants who completed the SLM to 20-week and 12-month follow-up assessments (all p values < 0.01). Barriers to completion were limited access to patients requiring spirometry, high clinic workload, and having a different spirometer at the workplace compared to the one used during SLM demonstrations. Our data suggest that participants' confidence, experience, and knowledge regarding spirometry may improve through SLM completion.

Efficacy and safety of 20% albumin fluid loading in healthy subjects: a comparison of four resuscitation fluids

Recently, buffered salt solutions and 20% albumin (small volume resuscitation) have been advocated as an alternative fluid for intravenous resuscitation. The relative comparative efficacy and potential adverse effects of these solutions have not been evaluated. In a randomized, double blind, cross-over study of six healthy male subjects we compared the pulmonary and hemodynamic effects of intravenous administration of 30 ml/kg of 0.9% saline, Hartmann's solution and 4% albumin, and 6 ml/kg of 20% albumin (albumin dose equivalent). Lung tests (spirometry, ultrasound, impulse oscillometry, diffusion capacity, and plethysmography), two- to three-dimensional Doppler echocardiography, carotid applanation tonometry, blood gases, serum/urine markers of endothelial, and kidney injury were measured before and after each fluid bolus. Data were analyzed with repeated measures ANOVA with effect of fluid type examined as an interaction. Crystalloids caused lung edema [increase in ultrasound B line ( P = 0.006) and airway resistance ( P = 0.009)], but evidence of lung injury [increased angiopoietin-2 ( P = 0.019)] and glycocalyx injury [increased syndecan ( P = 0.026)] was only observed with 0.9% saline. The colloids caused greater left atrial stretch, decrease in lung volumes, and increase in diffusion capacity than the crystalloids, but without pulmonary edema. Stroke work increased proportionally to increase in preload with all four fluids ( R2 = 0.71). There was a greater increase in cardiac output and stroke volume after colloid administration, associated with a reduction in afterload. Hartmann’s solution did not significantly alter ventricular performance. Markers of kidney injury were not affected by any of the fluids administrated. Bolus administration of 20% albumin is both effective and safe in healthy subjects.

NEW & NOTEWORTHY Bolus administration of 20% albumin is both effective and safe in healthy subjects when compared with other commonly available crystalloids and colloidal solution.

Bolus intravenous 0.9% saline, but not 4% albumin or 5% glucose, causes interstitial pulmonary edema in healthy subjects

Rapid intravenous (iv) infusion of 0.9% saline alters respiratory mechanics in healthy subjects. However, the relative cardiovascular and respiratory effects of bolus iv crystalloid vs. colloid are unknown. Six healthy male volunteers were given 30 ml/kg iv 0.9% saline, 4% albumin, and 5% glucose at a rate of 100 ml/min on 3 separate days in a double-blinded, randomized crossover study. Impulse oscillometry, spirometry, lung volumes, diffusing capacity (DLCO), and blood samples were measured before and after fluid administration. Lung ultrasound B-line score (indicating interstitial pulmonary edema) and Doppler echocardiography indices of cardiac preload were measured before, midway, immediately after, and 1 h after fluid administration. Infusion of 0.9% saline increased small airway resistance at 5 Hz (P = 0.04) and lung ultrasound B-line score (P = 0.01) without changes in Doppler echocardiography measures of preload. In contrast, 4% albumin increased DLCO, decreased lung volumes, and increased the Doppler echocardiography mitral E velocity (P = 0.001) and E-to-lateral/septal e' ratio, estimated blood volume, and N-terminal pro B-type natriuretic peptide (P = 0.01) but not lung ultrasound B-line score, consistent with increased pulmonary blood volume without interstitial pulmonary edema. There were no significant changes with 5% glucose. Plasma angiopoietin-2 concentration increased only after 0.9% saline (P = 0.001), suggesting an inflammatory mechanism associated with edema formation. In healthy subjects, 0.9% saline and 4% albumin have differential pulmonary effects not attributable to passive fluid filtration. This may reflect either different effects of these fluids on active signaling in the pulmonary circulation or a protective effect of albumin.

Heliox, dyspnoea and exercise in COPD

One of the most important determinants of physical and mental well-being of people with chronic obstructive pulmonary disease (COPD) is participation in physical activity. The ability to alter the sensation of dyspnoea during exercise may improve both exercise duration and intensity. Despite the low density, inert nature, strong safety profile and multiple applications of helium gas, the potential benefit of helium-oxygen gas mixtures as an adjunct therapy to modify disease symptoms and exercise capabilities in obstructive lung diseases has only recently been explored. This is a systematic review of the available peer-reviewed evidence exploring whether symptom modification (perceived levels of dyspnoea) and exercise performance in COPD (either intensity or duration of work) are modified by inhalation of Heliox. Eight experimental studies met inclusion for this review. A variety of methodologies and outcome variables were used negating meta-analysis and hampering direct comparison between interventions. Overall, there was high level of evidence with a low risk of bias supporting Heliox's effectiveness in improving the intensity and endurance of exercise when compared to room air for people with COPD. Little conclusive evidence was found to determine whether Heliox altered the sensation of dyspnoea during exercise.