Correlation of Oxygenation and Radiographic Assessment of Lung Edema (RALE) Score to Lung Ultrasound Score (LUS) in Acute Respiratory Distress Syndrome (ARDS) Patients in the Intensive Care Unit

Hydrochloric Acid-Induced Acute Lung Injury Models: Dynamic Change and Quantitative Analysis of Modified Lung Ultrasound Scoring System and High-Resolution Computed Tomography

OBJECTIVE

Acute lung injury (ALI) has become a research hotspot due to its significant public health impact. To explore the value of the use of modified lung ultrasound (MLUS) scoring system for evaluating ALI using a rabbit model of ALI induced by hydrochloric acid (HCl) and investigate its correlation with high-resolution computed tomography (HRCT) and histopathological scores.

METHODS

Twenty New Zealand laboratory rabbits were randomly assigned to control group (N = 5) and 3 experimental groups (N = 5 each). The control group received instillation of physiological saline, while the 3 experimental groups received 2 mL/kg of different doses of HCl instillation (mild group: pH 1.5, moderate group: pH 1.2, and severe group: pH 1.0) through the trachea under ultrasound guidance. Pulmonary ultrasound (using Mindray Reason9 linear array probes with frequency of 6-15 mHz) and HRCT examinations were performed before modeling (0H) and at 1H, 2H, 4H, 8H, 12H after modeling. The experimental rabbits were sacrificed at 12H for examination of gross lung morphology and hematoxylin-eosin-stained histopathological sections. The correlation of MLUS scores with HRCT/histopathological scores was assessed.

RESULTS

All rabbits in the experimental groups showed oxygenation index PaO₂/FiO₂<300. Successful establishment of ALI model was proven by autopsy (successful modeling rate: 100%). The pathological damage increased with increase in HCl dosage. MLUS scores showed a positive correlation with HRCT scores/pathological severity. There was a strong positive correlation between MLUS scores and histopathological scores (r = 0.963, p < 0.05) as well as between HRCT scores and histopathological scores (r = 0.932, p < 0.05).

CONCLUSION

Transtracheal injection of different dosages of HCl under ultrasound guidance induced different degrees of ALI. The MLUS scoring system can be used for semiquantitative evaluation of ALI, and is suitable as a screening tool.

The Role of Pocus in Acute Respiratory Failure: A Narrative Review on Airway and Breathing Assessment

Acute respiratory failure (ARF) is a challenging condition that clinicians, especially in emergency settings, have to face frequently. Especially in emergency settings, many underlying diseases can lead to ARF and life-threatening conditions have to be promptly assessed and correctly treated to avoid unfavorable outcomes. In recent years, point-of-care ultrasound (POCUS) gained growing consideration due to its bedside utilization, reliability and reproducibility even in emergency settings especially in unstable patients. Research on POCUS application to assess ARF has been largely reported mainly with observational studies showing heterogeneous results from many different applications. This narrative review describes the wide potentiality of POCUS to face airways and breathing life-threatening conditions such as upper airway management, pulmonary and pleural pathologies and diaphragm impairment. We conducted extensive research of the literature to report from major studies to case reports deemed useful in practical clinical utilization of POCUS in ARF. Due to the huge amount of the literature found, we focused on airways and breathing assessment trying to systematize the evidence according to clinical care of ARF in emergency settings. Further studies, possibly trials, should determine how POCUS is crucial in clinical practice in terms of standard of care improvements, patient safety and cost-benefit analysis.

Correlation between hypoxaemia and lung ultrasound score in patients presenting to an emergency department with interstitial syndrome: a prospective physiological study

Objective: To assess for the presence of a correlation between lung ultrasound score (LUSS) and ratio between arterial partial pressure of oxygen (PaO2) and the fraction of inspired oxygen (FiO2) in patients presenting to an emergency department (ED) with interstitial syndrome (IS). Design: Prospective, multicentre, physiological study. Setting: Four Belgian hospitals: one tertiary academic centre and three secondary centres. Participants: A convenience sample of adult patients who presented to an ED with acute dyspnoea and needed an arterial blood gas (ABG) analysis (those with a LUSS < 2 were secondarily excluded). Main outcome measure: Correlation between PaO2/FIO2 and LUSS determined using Pearson correlation. Results: In total, 162 adult patients were included. A statistically significant negative linear correlation between PaO2/FIO2 and LUSS was found (correlation coefficient, -0.4860 [95% CI, -0.5956 to -0.3587]; P < 0.0001). Conclusions: Our data provide evidence of a statistically significant negative linear correlation between PaO2/FIO2 and LUSS for ED patients with lung IS. Given the representativeness of PaO2/FIO2 for hypoxaemia and the fact that hypoxaemia indicates IS severity, our findings suggest that LUSS could contribute to the evaluation of IS severity. If confirmed by future studies that include patient follow-up, a noninvasive approach using LUSS could decrease the need for ABG analysis in patients who do not require repeated measurement of ABG values other than PaO2, and thereby improve patient comfort.

The Prognostic Capacity of the Radiographic Assessment for Lung Edema Score in Patients With COVID-19 Acute Respiratory Distress Syndrome-An International Multicenter Observational Study

Background: The radiographic assessment for lung edema (RALE) score has an association with mortality in patients with acute respiratory distress syndrome (ARDS). It is uncertain whether the RALE scores at the start of invasive ventilation or changes thereof in the next days have prognostic capacities in patients with COVID-19 ARDS.

Aims and Objectives: To determine the prognostic capacity of the RALE score for mortality and duration of invasive ventilation in patients with COVID-19 ARDS.

Methods: An international multicenter observational study included consecutive patients from 6 ICUs. Trained observers scored the first available chest X-ray (CXR) obtained within 48 h after the start of invasive ventilation (“baseline CXR”) and each CXRs thereafter up to day 14 (“follow-up CXR”). The primary endpoint was mortality at day 90. The secondary endpoint was the number of days free from the ventilator and alive at day 28 (VFD-28).

Results: A total of 350 CXRs were scored in 139 patients with COVID-19 ARDS. The RALE score of the baseline CXR was high and was not different between survivors and non-survivors (33 [24–38] vs. 30 [25–38], P = 0.602). The RALE score of the baseline CXR had no association with mortality (hazard ratio [HR], 1.24 [95% CI 0.88–1.76]; P = 0.222; area under the receiver operating characteristic curve (AUROC) 0.50 [0.40–0.60]). A change in the RALE score over the first 14 days of invasive ventilation, however, had an independent association with mortality (HR, 1.03 [95% CI 1.01–1.05]; P < 0.001). When the event of death was considered, there was no significant association between the RALE score of the baseline CXR and the probability of being liberated from the ventilator (HR 1.02 [95% CI 0.99–1.04]; P = 0.08).

Conclusion: In this cohort of patients with COVID-19 ARDS, with high RALE scores of the baseline CXR, the RALE score of the baseline CXR had no prognostic capacity, but an increase in the RALE score in the next days had an association with higher mortality.