Distribution of alveolar-interstitial syndrome in dogs and cats with respiratory distress as assessed by lung ultrasound versus thoracic radiographs.

Abstract

OBJECTIVE: To assess distribution of alveolar-interstitial syndrome (AIS) detected by lung ultrasound (LUS) compared to thoracic radiographs (TXR). DESIGN: Prospective study. SETTING: University teaching hospital. ANIMALS: Seventy-six dogs and 24 cats with acute respiratory distress or tachypnea. INTERVENTIONS: Patients underwent LUS and TXR within 6 hours. Lung ultrasound images were scored for presence and quantity of B-lines in 4 lung quadrants (right cranial, right caudal, left cranial, left caudal). An individual LUS quadrant was scored positive if > 3 B-lines were observed within a single intercostal space. Dorsoventral TXR were scored for presence of AIS in the same 4 quadrants. An individual TXR quadrant was scored positive if infiltrate was present in &#x2265; 25% of the quadrant. Medical records were evaluated for final diagnosis. MEASUREMENTS AND MAIN RESULTS: Quadrant-by-quadrant spatial agreement in assigning AIS using LUS versus TXR was fair (K&#xa0;=&#xa0;0.24 - 0.56). Lung ultrasound scored a higher number of quadrants positive per patient (2.65&#xa0;&#xb1;&#xa0;1.59 vs. 2.13&#xa0;&#xb1;&#xa0;1.48; P&#xa0;=&#xa0;0.012). Patterns of distribution of AIS differed significantly based on final diagnosis. Patients with left-sided congestive heart failure were more likely to have diffuse AIS on LUS (P&#xa0;<&#xa0;0.001) or bilateral caudal AIS on TXR (P&#xa0;=&#xa0;0.04) while patients with noncardiac disease were more likely to have absence of AIS in all quadrants using either modality (P&#xa0;<&#xa0;0.001). Differences in spatial distribution of AIS were also noted among disease subcategories. CONCLUSIONS: Lung ultrasound and TXR were both useful to detect and categorize distribution of alveolar or interstitial pulmonary pathology. Spatial agreement between modalities was only fair. Overall, LUS detected a higher incidence of AIS compared to TXR. Both modalities detected differences in distribution of AIS based on final diagnosis, suggesting that a regional pattern-based approach to thoracic imaging may prove diagnostically useful.