Fluid Balance Is Associated with Clinical Outcomes and Extravascular Lung Water in Children with Acute Asthma Exacerbation

An update on the role of fluid overload in the prediction of outcome in acute kidney injury

Over the past two decades, our understanding of the impact of acute kidney injury, disorders of fluid balance, and their interplay have increased significantly. In recent years, the epidemiology and impact of fluid balance, including the pathologic state of fluid overload on outcomes has been studied extensively across multiple pediatric and neonatal populations. A detailed understating of fluid balance has become increasingly important as it is recognized as a target for intervention to continue to work to improve outcomes in these populations. In this review, we provide an update on the epidemiology and outcomes associated with fluid balance disorders and the development of fluid overload in children with acute kidney injury (AKI). This will include a detailed review of consensus definitions of fluid balance, fluid overload, and the methodologies to define them, impact of fluid balance on the diagnosis of AKI and the concept of fluid corrected serum creatinine. This review will also provide detailed descriptions of future directions and the changing paradigms around fluid balance and AKI in critical care nephrology, including the incorporation of the sequential utilization of risk stratification, novel biomarkers, and functional kidney tests (furosemide stress test) into research and ultimately clinical care. Finally, the review will conclude with novel methods currently under study to assess fluid balance and distribution (point of care ultrasound and bioimpedance).

Association of Fluid Overload with Escalation of Respiratory Support and Endotracheal Intubation in Acute Bronchiolitis Patients

Fluid overload has been associated with increased oxygen requirement, prolonged duration of mechanical ventilation, and longer length of hospital stay in children hospitalized with pulmonary diseases. Critically ill infants with bronchiolitis admitted to the pediatric intensive care unit (PICU) also tend to develop fluid overload and there is limited information of its role on noninvasive respiratory support. Thus, our primary objective was to study the association of fluid overload in patients with bronchiolitis admitted to the PICU with respiratory support escalation (RSE) and need for endotracheal intubation (ETI). Infants ≤24 months of age with bronchiolitis and admitted to the PICU between 9/2009 and 6/2015 were retrospectively studied. Demographic variables, clinical characteristics including type of respiratory support and need for ETI were evaluated. Fluid overload as assessed by net fluid intake and output (net fluid balance), cumulative fluid balance (CFB) (mL/kg), and percentage fluid overload (FO%), was compared between patients requiring and not requiring RSE and among patients requiring ETI and not requiring ETI at 0 (PICU admission), 12, 24, 36, 48, 72, 96, and 120 hours. One-hundred sixty four of 283 patients with bronchiolitis admitted to the PICU qualified for our study. Thirty-four of 164 (21%) patients required escalation of respiratory support within 5 days of PICU admission and of these 34 patients, 11 patients required ETI. Univariate analysis by Kruskal-Wallis test of fluid overload as assessed by net fluid balance, CFB, and FO% between 34 patients requiring and 130 patients not requiring RSE and among 11 patients requiring ETI and 153 patients not requiring ETI, at 0, 12, 24, 36, 48, 72, 96 and 120 hours did not reveal any significant difference ( p >0.05) at any time interval. Multivariable logistic regression analysis revealed higher PRISM score (odds ratio [OR]: 4.95, 95% confidence interval [95% CI]: 1.79-13.66; p  = 0.002), longer hours on high flow nasal cannula (OR: 4.86, 95% CI: 1.68-14.03; p  = 0.003) and longer hours on noninvasive ventilation (OR: 11.16, 95% CI: 3.36-36.98; p  < 0.001) were associated with RSE. Fluid overload as assessed by net fluid balance, CFB, and FO% was not associated with RSE or need for ETI in critically ill bronchiolitis patients admitted to the PICU. Further prospective studies involving larger number of patients with bronchiolitis are needed to corroborate our findings.

Pathophysiology of coronavirus-19 disease acute lung injury

PURPOSE OF REVIEW

More than 230 million people have tested positive for severe acute respiratory syndrome-coronavirus-2 infection globally by September 2021. The infection affects primarily the function of the respiratory system, where ∼20% of infected individuals develop coronavirus-19 disease (COVID-19) pneumonia. This review provides an update on the pathophysiology of the COVID-19 acute lung injury.

RECENT FINDINGS

In patients with COVID-19 pneumonia admitted to the intensive care unit, the PaO2/FiO2 ratio is typically <26.7 kPa (200 mmHg), whereas lung volume appears relatively unchanged. This hypoxaemia is likely determined by a heterogeneous mismatch of pulmonary ventilation and perfusion, mainly associated with immunothrombosis, endothelialitis and neovascularisation. During the disease, lung weight, elastance and dead space can increase, affecting respiratory drive, effort and dyspnoea. In some severe cases, COVID-19 pneumonia may lead to irreversible pulmonary fibrosis.

SUMMARY

This review summarises the fundamental pathophysiological features of COVID-19 in the context of the respiratory system. It provides an overview of the key clinical manifestations of COVID-19 pneumonia, including gas exchange impairment, altered pulmonary mechanics and implications of abnormal chemical and mechanical stimuli. It also critically discusses the clinical implications for mechanical ventilation therapy.

Association of Obstructive Apnea with Thoracic Fluid Shift and Small Airways Narrowing in Asthma During Sleep

RATIONALE

Obstructive sleep apnea (OSA) is highly prevalent among patients with asthma, suggesting a pathophysiological link between the two, but a mechanism for this has not been identified.

HYPOTHESIS

Among patients with asthma, those with OSA will have greater overnight increases in thoracic fluid volume and small airways narrowing than those without OSA.

METHODS

We enrolled 19 participants with asthma: 9 with OSA (apnea-hypopnea index (AHI) ≥10) and 10 without OSA (AHI <10). All participants underwent overnight polysomnography. Before and after sleep, thoracic fluid volume was measured by bioelectrical impedance and small airways narrowing was primarily assessed by respiratory system reactance at 5Hz using oscillometry.

RESULTS

Patients with asthma and OSA (OSA group) had a greater overnight increase in thoracic fluid volume by 120.5 mL than patients without OSA (non-OSA group) (164.4 ± 44.0 vs 43.9 ± 47.3 mL, p=0.006). Compared to the non-OSA group, the OSA group had greater overnight decrease in reactance at 5Hz (-1.08 ± 0.75 vs 0.21 ± 0.27 cmH₂O/L/s, p=0.02), and overnight increase in reactance area (14.81 ± 11.09 vs -1.20 ± 2.46 cmH₂O/L, p=0.04), frequency dependence of resistance (1.02 ± 0.68 vs 0.05 ± 0.18 cmH₂O/L/s, p=0.04), and resonance frequency (2.80 ± 4.14 vs -1.42 ± 2.13 cmH₂O/L/s, p=0.04).

CONCLUSION

Patients with asthma and co-existing OSA had greater overnight accumulation of fluid in the thorax in association with greater small airways narrowing than those without OSA. This suggests OSA could contribute to worsening of asthma at night by increasing fluid accumulation in the thorax.

Kidney function and obstructive lung disease: a bidirectional Mendelian randomisation study

BACKGROUND

Additional study is warranted to investigate the causal effects between kidney function and obstructive lung disease.

METHODS

This study was a bidirectional two-sample Mendelian randomisation (MR) analysis. The CKDGen genome-wide association study (GWAS) meta-analysis for estimated glomerular filtration rate (eGFR) including individuals of European ancestry (N=567 460) provided the genetic instrument for kidney function and outcome summary statistics. A GWAS for FEV1/FVC including individuals of European ancestry from the UK Biobank (N=321 047) provided the genetic instrument for FEV1/FVC and outcome data. A polygenic score (PGS) analysis was performed to test the causal estimates from kidney function to binary obstructive lung disease outcomes, including chronic obstructive pulmonary disease (COPD), asthma, and FEV1/FVC<70%, and to perform non-linear MR with individual-level UK Biobank data.

RESULTS

The causal estimates by summary-level MR indicated that genetically predicted increased kidney function was significantly associated with increased FEV1/FVC Z scores [10% increase in eGFR, beta 0.055 (0.024, 0.086)]. The PGS for increased eGFR showed a significant association with a reduced risk of FEV1/FVC<70% [OR 0.93 (0.87, 0.99)], COPD [OR 0.93 (0.87, 0.99)] and late-onset (≥50 years old) asthma [OR 0.93 (0.88, 0.99)]. The non-linear MR demonstrated that the causal effect from eGFR to FEV1/FVC was apparent in eGFR ranges lower than 60 mL/min/1.73 m². On the other hand, genetically predicted FEV1/FVC showed nonsignificant causal estimates of eGFR change [beta 0.568% (-0.458, 1.605%)].

CONCLUSION

This study supports kidney function impairment would be a causative factor for obstructive lung disease.

Impact of spontaneous breathing during mechanical ventilation in acute respiratory distress syndrome

PURPOSE OF REVIEW

Facilitating spontaneous breathing has been traditionally recommended during mechanical ventilation in acute respiratory distress syndrome (ARDS). However, early, short-term use of neuromuscular blockade appears to improve survival, and spontaneous effort has been shown to potentiate lung injury in animal and clinical studies. The purpose of this review is to describe the beneficial and deleterious effects of spontaneous breathing in ARDS, explain potential mechanisms for harm, and provide contemporary suggestions for clinical management.

RECENT FINDINGS

Gentle spontaneous effort can improve lung function and prevent diaphragm atrophy. However, accumulating evidence indicates that spontaneous effort may cause or worsen lung and diaphragm injury, especially if the ARDS is severe or spontaneous effort is vigorous. Recently, such effort-dependent lung injury has been termed patient self-inflicted lung injury (P-SILI). Finally, several approaches to minimize P-SILI while maintaining some diaphragm activity (e.g. partial neuromuscular blockade, high PEEP) appear promising.

SUMMARY

We update and summarize the role of spontaneous breathing during mechanical ventilation in ARDS, which can be beneficial or deleterious, depending on the strength of spontaneous activity and severity of lung injury. Future studies are needed to determine ventilator strategies that minimize injury but maintaining some diaphragm activity.

Impact of fluid overload and infection on respiratory adverse event development during induction therapy for childhood acute myeloid leukemia

BACKGROUND

Treatment-related morbidity and mortality occur frequently in childhood acute myeloid leukemia (AML) induction. Yet the contributions of respiratory adverse events (AEs) within this population are poorly understood. Furthermore, the roles of fluid overload (FO) and infection in AML pulmonary complications have been inadequately examined.

OBJECTIVES

To describe the incidence, categories, and grades of respiratory AEs and to assess the associations of FO and infection on respiratory AE development in childhood AML induction.

METHODS

We retrospectively examined the induction courses of a cohort of de novo pediatric AML patients for any NCI CTCAE grade 2 to 5 respiratory AE, FO, and systemic/pulmonary infection occurrence. Demographic, disease, and treatment-related data were abstracted. Descriptive, univariate, survival, and multivariable analyses were conducted.

RESULTS

Among 105 eligible subjects from 2009 to 2016, 49.5% (n = 52) experienced 63 discrete respiratory AEs. FO occurred in 28.6% of subjects (n = 30), with half occurring within 24 hours of hospitalization. Positive FO status < 10 days (aHR 5.5, 95% CI 2.3-12.8), ≥ 10 days (aHR 13, 95% CI 4.1-41.8), and positive infection status ≥ 10 days into treatment (aHR 14.9, 5.4-41.6) were each independently associated with AE development.

CONCLUSIONS

We describe a higher incidence of respiratory AEs during childhood AML induction than previously illustrated. FO occurs frequently and early in this course. Late infections and FO at any time frame were strongly associated with AE development. Interventions focused on the prevention and management of FO and infectious respiratory complications could be instrumental in reducing preventable treatment-related morbidity and mortality.