Retrospective Evaluation of the Relationship Between Lung Ultrasound Score and Arterial Blood Gas Analysis in Dogs: Fifty-Six Examinations in 42 Cases (2022-2023).

Abstract

OBJECTIVE: To evaluate the relationship between the lung ultrasound score (LUSS) and oxygenation indices. DESIGN: Retrospective study from January 2022 to December 2023. SETTING: Private veterinary center. ANIMALS: A total of 56 examinations from 42 dogs were used for the analysis. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Arterial blood gas analysis was performed on room air. By summing the score assigned to eight quadrants, a LUSS was created that ranged from 0/24 for fully aerated lungs to 24/24 for nonaerated lungs. Represented conditions included pneumonia (n = 25), cardiogenic pulmonary edema (CPE; 14), pulmonary hypertension (6), systemic or extrathoracic diseases (5), lung contusion (3), and pulmonary thromboembolism (3). The LUSS had a moderate correlation with oxygenation indices, showing a negative relationship with the ratio between arterial partial pressure of oxygen and fraction of inspired oxygen (PaO:FiO): r = -0.79 (95% confidence interval [CI]: -0.87 to -0.662; p < 0.001) and a positive relationship with the alveolar-arterial gradient (Grad(A-a)O): r = 0.68 (95% CI: 0.502-0.797; p < 0.001). In pneumonia, this correlation was moderate with an r of -0.61 (95% CI: -0.809 to -0.28; p = 0.001), while in CPE, it was very strong, with r = -0.81 (95% CI: -0.938 to -0.49; p < 0.001). The relationship between the LUSS and the Grad(A-a)Owas weaker, with r = 0.48 (95% CI: 0.111-0.738; p = 0.014) for pneumonia and 0.6 (95% CI: 0.105-0.858; p = 0.023) for CPE. The correlation between the PaO/FiOratio and the Grad(A-a)Owas very strong, with r = -0.89 (95% CI: -0.934 to -0.817; p < 0.001). CONCLUSIONS: This study found a strong correlation between the LUSS and pulmonary oxygenation indices, suggesting that the LUSS is an effective tool for stratifying the severity of lung aeration loss and investigating respiratory status in healthy dogs as well as those with respiratory failure.