Evaluation of B‐lines with 2 point‐of‐care lung ultrasound protocols in cats with radiographically normal lungs

Abstract

AbstractObjectiveTo compare 2 point‐of‐care lung ultrasound (LUS) protocols for quantification of B‐lines in cats without evidence of respiratory disease based on history, physical examination, and thoracic radiography.DesignProspective observational study.SettingSingle center, veterinary teaching hospital.AnimalsFifty‐seven cats without respiratory disease based on history, physical examination, and thoracic radiographs.InterventionsAll cats had 2 point‐of‐care LUS protocols performed bilaterally: a regional protocol (veterinary bedside lung ultrasound evaluation [VetBLUE]) and a more comprehensive vertical sweeping (VS) protocol. The total number of B‐lines per cat, number of sites with B‐lines, and maximal number of B‐lines at each site were recorded and compared.Measurements and Main ResultsTen cats (18%) had at least 1 B‐line identified with VetBLUE, versus 29 (51%) with VS. Comparing protocols, VS had a statistically higher total number of B‐lines per cat, higher number of sites with B‐lines, and higher maximal number of B‐lines per site. B‐lines that were too numerous to count were identified at a single location in 1 cat with VetBLUE and 2 cats with VS. A maximum of 3 B‐lines were identified at all other positive sites regardless of the protocol used. On average, it took 1.79 times longer to complete VS bilaterally compared to VetBLUE (median [interquartile range]: 140 [33] and 78 [14] s, respectively) (P = 0.001).ConclusionsThis study demonstrates it is not uncommon to identify a single or even multiple B‐lines in 1 or several sites on LUS in cats deemed to be clinically free of respiratory pathology—essential knowledge when using LUS as a screening test and to monitor intrathoracic lesions. In cats asymptomatic for respiratory disease, VS generally identifies more B‐lines than VetBLUE, likely because it assesses a larger lung surface area. The sonographic identification of B‐lines should be interpreted considering the LUS protocol used, history, and other diagnostics to determine their clinical significance.