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

Abstract

To 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. Prospective observational study. Single center, veterinary teaching hospital. Fifty-seven cats without respiratory disease based on history, physical examination, and thoracic radiographs. All 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. Ten 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). This 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.