Validation of a Rapid Bronchoalveolar Lavage Fluid Colorimetric Evaluation for Assessing the Severity of Exercise-Induced Pulmonary Hemorrhage in Horses in Field Conditions

Abstract

Diagnosis and assessment of severity of exercise-induced pulmonary hemorrhage (EIPH) relies on postexercise visualization of fresh blood in the airways via tracheobronchoscopic examination (TBE) and/or counting erythrocytes in bronchoalveolar lavage fluid (BALFRBC). Determining the BALFRBC is more sensitive than TBE but its usefulness is hampered by the need to have BALFRBC counted at a laboratory. We explored the feasibility of evaluating the severity of EIPH by using a color chart comprised of five shades of red and matching those colors with the color of BALF immediately following collection. To validate the technique, sets of ten BALF samples with known BALFRBC numbers were created and randomly shown to two groups of 18 observers who independently matched the color of the BALF with one of the shades of red displayed on the screen of a smartphone. Interobserver and intra-observer agreements regarding colors were > 0.9. The utility of the color chart was further validated under field conditions at two barrel racing events where 63 BALF samples were collected from 21 horses and BALF color was graded independently by three observers. The number of BALFRBC in the 63 samples ranged from 25-1,100,000/μL. EIPH was diagnosed in 39 samples based on the detection of color, and all 5 colors were matched multiple times with BALF samples. Overall, the color of the BALF was related to the number of BALFRBC. Colorimetric evaluation of BALF represents a practical and reliable option for rapid postexercise assessment of the presence and severity of EIPH.

Keywords: Bronchoalveolar lavage erythrocyte number; Color; EIPH severity.