Ultrasound-assessed lung aeration correlates with respiratory system compliance in adults and neonates with acute hypoxemic restrictive respiratory failure: an observational prospective study.

BACKGROUND: Lung ultrasound allows lung aeration to be assessed through dedicated lung ultrasound scores (LUS). Despite LUS have been validated using several techniques, scanty data exist about the relationships between LUS and compliance of the respiratory system (Crs) in restrictive respiratory failure. Aim of this study was to investigate the relationship between LUS and Crs in neonates and adults affected by acute hypoxemic restrictive respiratory failure, as well as the effect of patients' age on this relationship. METHODS: Observational, cross-sectional, international, patho-physiology, bi-center study recruiting invasively ventilated, adults and neonates with acute respiratory distress syndrome (ARDS), neonatal ARDS (NARDS) or respiratory distress syndrome (RDS) due to primary surfactant deficiency. Subjects without lung disease (NLD) and ventilated for extra-pulmonary conditions were recruited as controls. LUS, Crs and resistances (Rrs) of the respiratory system were measured within 1 h from each other. RESULTS: Forty adults and fifty-six neonates were recruited. LUS was higher in ARDS, NARDS and RDS and lower in control subjects (overall p < 0.001), while Crs was lower in ARDS, NARDS and RDS and higher in control subjects (overall p < 0.001), without differences between adults and neonates. LUS and Crs were correlated in adults [r = - 0.86 (95% CI - 0.93; - 0.76), p < 0.001] and neonates [r = - 0.76 (95% CI - 0.85; - 0.62), p < 0.001]. Correlations remained significant among subgroups with different causes of respiratory failure; LUS and Rrs were not correlated. Multivariate analyses confirmed the association between LUS and Crs both in adults [B = - 2.8 (95% CI - 4.9; - 0.6), p = 0.012] and neonates [B = - 0.045 (95% CI - 0.07; - 0.02), p = 0.001]. CONCLUSIONS: Lung aeration and compliance of the respiratory system are significantly and inversely correlated irrespective of patients' age. A restrictive respiratory failure has the same ultrasound appearance and mechanical characteristics in adults and neonates.

Thromboelastography Profile Is Associated with Lung Aeration Assessed by Point-of-Care Ultrasound in COVID-19 Critically Ill Patients: An Observational Retrospective Study.

Background. To evaluate relationships between lung aeration assessed by lung ultrasound (LUS) with viscoelastic profiles obtained by thromboelastography (TEG) in COVID-19 respiratory failure. Methods. Retrospective analysis in a tertiary ICU in Rome, Italy. Forty invasively ventilated adults with COVID-19 underwent LUS and TEG assessment. A simplified LUS protocol consisting in scanning six areas, three per side, was adopted. A score from 0 to 3 was assigned to each area. TEG®6s was used to obtain viscoelastic hemostatic assay parameters which were compared to LUS score. Results. There was a significant inverse correlation between LUS score and static compliance of the respiratory system (Crs, rs −0.75; p < 0.001). We found a significant association between LUS and functional fibrinogen maximum amplitude (FF-MA): among 18 patients with LUS score ≤ 12, median FF-MA was 31 mm [IQR 28−39] whilst, among 22 patients with LUS score > 12, it was 46.3 mm [IQR 40−53], p = 0.0004. Median of the citrated recalcified kaolin-activated maximum amplitude (CK-MA) was 66.1 mm [64.4−68] in the LUS score ≤ 12 group, and 69.6 [68.5−70.7] when LUS score > 12, p < 0.002. Conclusions. The hypercoagulable profile as defined by elevated FF-MA and CK-MA may be associated with a low degree of lung aeration as assessed by LUS.