Quantifying pulmonary hypertension in ventilated infants with bronchiolitis: a pilot study

Echocardiographic Markers of Mild Pulmonary Hypertension are not Correlated with Worse Respiratory Outcomes in Infants with Bronchiolitis

Pulmonary hypertension has been reported as a crucial factor in the pathophysiology of severe bronchiolitis. The aim of this study was to evaluate pulmonary artery pressure (PAP) in patients with bronchiolitis and to analyze their correlation with clinical outcomes. This prospective cohort study examined children admitted for bronchiolitis. PAP was assessed by right ventricle (RV) acceleration/ejection time ratio (AT/ET), isovolumic relaxation time, eccentricity index, and the presence of a pulmonary systolic notch. Pulmonary hypertension (PH) was considered if at least two altered parameters were present. Severity of clinical course was established by higher N-terminal (NT)-prohormone BNP (NT-proBNP) values, the need for positive pressure respiratory support (PPRS), and the duration of hospital admission. One hundred sixty-nine children were included in analysis. Sixty-eight patients (40%) required PPRS, and those patients had increased NT-proBNP values and worse tricuspid annular systolic excursion (TAPSE) compared to mild cases (p < 0.001and p < 0.001, respectively). Twenty-two (13%) cases had at least two altered parameters of PAP and met criteria for presumed PH, with no differences in NT-proBNP values, TAPSE, need for PPRS or hospital length of stay compared to normal PAP group (p = 0.98, p = 0.07, p = 0.94 and p = 0.64, respectively). We found no correlation between altered RV AT/ET and worse cardiac function, NT-proBNP values or hospital length of stay. In our cohort, the presence of echocardiographic findings of PH were not associated with worse clinical outcomes. Patients with severe bronchiolitis had higher values ​​of NT-proBNP but, interestingly, no clear association with PH.

The Assessment of Myocardial Strain by Cardiac Imaging in Healthy Infants with Acute Bronchiolitis: A Systematic Review and Meta-Analysis

This study aims to systematically review the incidence of myocardial strain detected by echocardiography in previously healthy infants with acute bronchiolitis and its role as a predictor for adverse outcomes in this setting.

METHODS

Pubmed/Medline, Excerpta Medica Data Base (EMBASE), and Cochrane Library were searched in April 2020 to identify original observational prospective studies that systematically performed echocardiography for the screening of myocardial strain in healthy infants with acute bronchiolitis. Pooled estimates were generated using random-effects models. Heterogeneity within studies was assessed using Cochran's Q and I² statistics. Funnel plots and Egger´s regression method were constructed to evaluate publication bias. Sensitivity analyses were also conducted to evaluate potential sources of heterogeneity.

RESULTS

After a detailed screening of 305 articles, a total of 10 studies with 395 participants (mean of 40 participants per study) was included. Five of them were classified as high-quality studies. Up to 28% of cases presented adverse outcomes. The echocardiographic screening for myocardial strain was performed within the first 24 h of admission in 92% cases. Tissue Doppler imaging and Speckle-Tracking echocardiography were performed only in 20% of cases. The presence of pulmonary hypertension was evaluated with methods different from the tricuspid regurgitation jet in 64% of cases. Seven studies found some grade of myocardial strain with a pooled incidence of 21% (CI 95%, 11-31%), in the form of pulmonary hypertension (pooled incidence of 20% (CI 95%, 11-30%)), and myocardial dysfunction (pooled incidence of 5% (CI 95%, 1-9%)). The presence of these echocardiographic alterations was associated with adverse outcomes (pooled relative risk = 16; CI 95%, 8.2-31.5). After a subgroup analysis based on the echocardiographic techniques used, no significant heterogeneity across the studies was observed. There was no evidence of publication bias when assessed by Egger´s test. Cardiac biomarkers to assess myocardial strain were used in five studies. Only N-terminal-pro-brain natriuretic peptide accurately predicted the presence of myocardial strain by echocardiography.

CONCLUSIONS

Myocardial strain is not infrequent in previously healthy infants with acute bronchiolitis, and it could be present at the early stages of the disease with prognostic implications. There is a need for sufficiently powered prospective studies with a similar methodology, preferably employing advanced imaging techniques, to conclusively address the usefulness of the assessment of myocardial strain in this setting.

Left Ventricular Dysfunction and Plasmatic NT-proBNP Are Associated with Adverse Evolution in Respiratory Syncytial Virus Bronchiolitis

AIM

To investigate whether the presence of left ventricular myocardial dysfunction (LVMD) assessed by Tei index (LVTX) impacts the outcomes of healthy infants with Respiratory Syncytial Virus Bronchiolitis (RSVB). To explore whether N-terminal pro-B-type natriuretic peptide (NT-proBNP) increases the accuracy of traditional clinical markers in predicting the outcomes.

METHODS

A single-centre, prospective, cohort study including healthy infants aged 1-12 months old admitted for RSVB between 1 October 2016 and 1 April 2017. All patients underwent clinical, laboratory and echocardiographic evaluation within 24 h of admission. Paediatric intensive care unit (PICU) admission was defined as severe disease.

RESULTS

We enrolled 50 cases of RSVB (median age of 2 (1-6.5) months; 40% female) and 50 age-matched controls. We observed higher values of LVTX in infants with RSVB than in controls (0.42 vs. 0.36; p = 0.008). Up to nine (18%) children presented with LVMD (LVTX > 0.5), with a higher incidence of PICU admission (89% vs. 5%; p < 0.001). The diagnostic performance of NT-proBNP in predicting LVMD was high (area under the receiver operator characteristic curve (AUC) 0.95, CI 95% 0.90-1). The diagnostic yield of the predictive model for PICU admission that included NT-proBNP was excellent (AUC 0.945, CI 95% 0.880-1), and significantly higher than the model without NT-proBNP (p = 0.026).

CONCLUSIONS

LVMD could be present in healthy infants with RSVB who develop severe disease. NT-proBNP seems to improve traditional clinical markers for outcomes.

NT-proBNP plasma levels as biomarkers for pulmonary hypertension in healthy infants with respiratory syncytial virus infection

Aim: To explore NT-proBNP as biomarker for pulmonary hypertension (PH) in infants with respiratory syncytial virus infection (RSVI). Patients & methods: We prospectively enrolled 93 healthy infants with RSVI aged 1-12 months. NT-proBNP determination and echocardiography were performed at admission. Results: PH was found in 22% of patients and associated with a severe course of the disease. NT-proBNP >1635 pg/ml resulted an independent predictor for PH (odds ratio: 16.46 [95% CI: 4.10-66; p < 0.001]). The diagnostic performance of NT-proBNP to detect PH in RSVI was high (area under receiver operator curve of 0.932 [95% CI: 0.883-0.981; p < 0.001]). Conclusions: The presence of PH in healthy infants with RSVI is associated with worse outcomes. NT-proBNP resulted an accurate biomarker for PH in this setting.

Pulmonary hypertension during respiratory syncytial virus bronchiolitis: a risk factor for severity of illness

BACKGROUND

Respiratory syncytial virus infection is the most frequent cause of acute lower respiratory tract disease in infants. A few reports have suggested that pulmonary hypertension is associated with increased severity of respiratory syncytial virus infection. We sought to determine the association between the pulmonary hypertension detected by echocardiography during respiratory syncytial virus bronchiolitis and clinical outcomes.

METHODS

We retrospectively reviewed 154 children admitted with respiratory syncytial virus bronchiolitis who had an echocardiography performed during the admission. The association between pulmonary hypertension and clinical outcomes including mortality, intensive care unit (ICU) admission, prolonged ICU stay (&gt;10 days), tracheal intubation, and need of high frequency oscillator ventilation was evaluated.

RESULTS

Echocardiography detected pulmonary hypertension in 29 patients (18.7%). Pulmonary hypertension was observed more frequently in patients with congenital heart disease (CHD) (n = 11/33, 33%), chronic lung disease of infancy (n = 12/25, 48%), prematurity (&lt;37 weeks gestational age, n = 17/59, 29%), and Down syndrome (n = 4/10, 40%). The presence of pulmonary hypertension was associated with morbidity (p &lt; 0.001) and mortality (p = 0.02). However, in patients without these risk factors (n = 68), pulmonary hypertension was detected in five patients who presented with shock or poor perfusion. Chronic lung disease was associated with pulmonary hypertension (OR = 5.9, 95% CI 2.2-16.3, p = 0.0005). Multivariate logistic analysis demonstrated that pulmonary hypertension is associated with ICU admission (OR = 6.4, 95% CI 2.2-18.8, p = 0.0007), intubation (OR = 4.7, 95% CI 1.8-12.3, p = 0.002), high frequency oscillator ventilation (OR = 8.4, 95% CI 2.95-23.98, p &lt; 0.0001), and prolonged ICU stay (OR = 4.9, 95% CI 2.0-11.7, p = 0.0004).

CONCLUSIONS

Pulmonary hypertension detected by echocardiography during respiratory syncytial virus infection was associated with increased morbidity and mortality. Chronic lung disease was associated with pulmonary hypertension detected during respiratory syncytial virus bronchiolitis. Routine echocardiography is not warranted for previously healthy, haemodynamically stable patients with respiratory syncytial virus bronchiolitis.

A Case of Bilateral Spontaneous Chylothorax with Respiratory Syncytial Virus Bronchiolitis

A case of bilateral spontaneous chylothorax with respiratory syncytial virus (RSV) bronchiolitis has never been reported. We report the case of a 7-month-old boy born at 33 weeks gestation with a history of Down syndrome, atrial septal defect, pulmonary hypertension, and chronic lung disease, hospitalized due to RSV bronchiolitis who developed bilateral spontaneous chylothorax with exacerbation of pulmonary hypertension (PH). The patient died after 9 weeks of mechanical ventilation and treatment for PH. The autopsy showed acute infectious signs, a chronic interstitial lung disease with pulmonary hypertensive changes and subpleural cysts with no evidence of congenital lymphangiectasia. The cause of chylothorax in this child could be multifactorial. However, worsening pulmonary hypertension with RSV infection might have partially contributed to the development of chylothorax through elevated superior venous cava pressure. Thoracentesis should be considered for patients with Down syndrome and PH associated with congenital heart disease who develop persistent pleural effusion during RSV bronchiolitis to rule out chylothorax.

Unrecognized prolonged viral replication in the pathogenesis of human RSV infection

BACKGROUND

Respiratory symptoms in RSV persist long after the virus is no longer detected by culture. Current concepts of RSV pathogenesis explain this by RSV inducing a long-lasting pathogenic immune cascade. We alternatively hypothesized that prolonged unrecognized RSV replication may be responsible and studied this possibility directly in a human wild-type RSV experimental infection model.

OBJECTIVE

The objective of the current report was to define the duration of true human RSV replication by studying it directly in immunocompetent adults experimentally infected with a clinical strain of RSV utilizing this previously established safe and reproducible model.

STUDY DESIGN

35 healthy adult volunteers were inoculated with RSV-A (Memphis-37, a low11 passage clinical strain virus, manufactured from a hospitalized bronchiolitic infant) and evaluated over 12 days. Viral load by culture, parallel quantitative PCR (genomic, message) and RSV-specific IgA, were measured twice daily from serially collected nasal washes.

RESULTS

After inoculation, 77% (27/35) of volunteers became RSV infected. As expected, culture-detectable RSV ceased abruptly by the 5-6 t h 15 infection day. However, infected volunteers demonstrated prolonged RSV presence by both genomic and message PCR. RSV-specific IgA rose within respiratory secretions of infected volunteers during same time frame.

CONCLUSIONS

RSV replication appears to continue in humans far longer than previously thought. The rise in nasal RSV-specific IgA shortly after infection likely neutralizes culture detectable virus producing misleadingly short durations of infection. Prolonged viral replication helps explain RSV's extended disease manifestations and increases the potential utility of antivirals.

New mouse model of pulmonary hypertension induced by respiratory syncytial virus bronchiolitis

Pulmonary hypertension (PH) has been observed in up to 75% of infants with moderate to severe respiratory syncytial virus (RSV) bronchiolitis and is associated with significant morbidity and mortality in infants with congenital heart disease. The purpose of the present study was to establish a mouse model of PH secondary to RSV bronchiolitis that mimics the disease etiology as it occurs in infants. Neonatal mice were infected with RSV at 5 days of age and then reinfected 4 wk later. Serum-free medium was administered to age-matched mice as a control. Echocardiography and right ventricular systolic pressure (RVSP) measurements via right jugular vein catheterization were conducted 5 and 6 days after the second infection, respectively. Peripheral capillary oxygen saturation monitoring did not indicate hypoxia at 2-4 days post-RSV infection, before reinfection, and at 2-7 days after reinfection. RSV-infected mice had significantly higher RVSP than control mice. Pulsed-wave Doppler recording of the pulmonary blood flow by echocardiogram demonstrated a significantly shortened pulmonary artery acceleration time and decreased pulmonary artery acceleration time-to-ejection time ratio in RSV-infected mice. Morphometry showed that RSV-infected mice exhibited a significantly higher pulmonary artery medial wall thickness and had an increased number of muscularized pulmonary arteries compared with control mice. These findings, confirmed by RVSP measurements, demonstrate the development of PH in the lungs of mice infected with RSV as neonates. This animal model can be used to study the pathogenesis of PH secondary to RSV bronchiolitis and to assess the effect of treatment interventions. NEW & NOTEWORTHY This is the first mouse model of respiratory syncytial virus-induced pulmonary hypertension, to our knowledge. This model will allow us to decipher molecular mechanisms responsible for the pathogenesis of pulmonary hypertension secondary to respiratory syncytial virus bronchiolitis with the use of knockout and/or transgenic animals and to monitor therapeutic effects with echocardiography.

Addressing the challenges of phenotyping pediatric pulmonary vascular disease

Pediatric pulmonary vascular disease (PVD) and pulmonary hypertension (PH) represent phenotypically and pathophysiologically diverse disease categories, contributing substantial morbidity and mortality to a complex array of pediatric conditions. Here, we review the multifactorial nature of pediatric PVD, with an emphasis on improved recognition, phenotyping, and endotyping strategies for pediatric PH. Novel tailored approaches to diagnosis and treatment in pediatric PVD, as well as the implications for long-term outcomes, are highlighted.

Pulmonary hypertension in chronic neonatal lung disease

Pulmonary hypertension is an uncommon but significantly challenging complication of chronic neonatal lung disease [CNLD] as it occurs in the "new bronchopulmonary dysplasia [BPD]". The presence of pulmonary hypertension may be sub-clinical and is often overlooked as it is not considered in all but the more severe cases of children with CNLD. Whilst the mainstays of therapy are supplemental oxygen and time and the majority of children will have resolution of their pulmonary hypertension with lung growth, the advent of newer pharmacological treatments has offered stability and perhaps a better prognosis for more severe cases of pulmonary hypertension.

Going to High Altitude with a Newborn Infant

Fetal life conditions the responses of a newborn infant to high altitude. The fetal circulation is characterized by high pulmonary vascular resistance and low pulmonary blood flow, as well as intra and extracardiac shunts that serve to route blood to and from the placenta and around the fetal lungs. At birth, rapid changes occur in the pulmonary circulation under normoxia; pulmonary vascular resistance falls, pulmonary blood flow increases dramatically, and the fetal shunts close functionally, then anatomically. Under conditions of hypoxia, the changes of circulatory transition occur more slowly, and pronounced hypoxia can cause a reversion to fetal circulatory patterns, albeit without the placenta to serve as the organ of oxygenation. Underlying medical conditions of newborn infants that combine exaggerated hypoxemia in response to high altitude hypoxia with an underlying predisposition to pulmonary hypertension can increase the likelihood of problems at high altitude. Awareness of risk factors and clinical signs of hypoxemia in newborn infants, as well as measurement of arterial oxygen saturation by pulse oximetry, can aid health professionals and parents in recognizing and preventing altitude-associated illness.

Effectiveness of drug therapies to treat or prevent respiratory syncytial virus infection-related morbidity

Respiratory syncytial virus (RSV) infection causes a huge burden to the health service, as it results in a large number of in-patient days each year and increases the risk of asthma in childhood. In the acute phase, therapy is supportive as bronchodilators and corticosteroids have resulted, at best, only in short-term benefits; promising treatments for ventilated patients, such as exogenous surfactant, require further testing. Passive immunoprophylaxis reduces hospital admission in high risk groups. In the prevention of chronic respiratory morbidity following RSV infection, however, studies are needed to determine whether immunoprophylaxis will have a useful role and to identify which drug treatment will be most cost-effective.

Current treatment for acute viral bronchiolitis in infants

This paper provides an update and critical review of available data on the treatment of acute viral bronchiolitis in previously healthy infants, with special focus on new or promising therapies. The main potential benefits of medical assistance in these patients reside in the careful monitoring of their clinical status, the maintenance of adequate hydration and oxygenation, the preservation of the airway opened and cleared of secretions and the option to perform parental education. There is no convincing evidence that any other form of therapy will reliably provide beneficial effects in infants with bronchiolitis and currently, any treatment beyond supportive care should be prescribed on a case-by-case basis with watchful appraisal of its effects. Therapies such as ribavirin, IFN, vitamin A, antibiotics, mist therapy or anticholinergics, have not demonstrated any measurable clinical effect. Several studies and meta-analyses with beta(2)-agonists and corticosteroids have failed to show any benefit of significant extent, however, physicians keep favouring their use. Presently, adrenaline has received rather consistent support from clinical trials but it is not yet widely prescribed. There are other therapeutic strategies, for instance, heliox, hypertonic saline, noninvasive ventilation, physical therapy techniques, thickened feeds or palivizumab that have shown promising potential benefits, but evidence supporting its use is still limited and further studies should be warranted. In the meantime, infants with acute viral bronchiolitis should be treated following evidence-based clinical practice guidelines, keeping the patient central in the process and being sensitive to social, cultural and familiar influences on their treatment strategy.