Relationship between tracheobronchoscopic score and BAL cytology for dx of EIPH

Not a surprise but serves as a reminder: some horses with low tracheobronchoscopic scores have significant bleeding.

J Vet Intern Med. 2019 Dec 27. doi: 10.1111/jvim.15676. [Epub ahead of print]
Relationship between tracheobronchoscopic score and bronchoalveolar lavage red blood cell numbers in the diagnosis of exercise-induced pulmonary hemorrhage in horses.
Lopez Sanchez CM1, Kogan C2, Gold JR1, Sellon DC1, Bayly WM1.
Author information

1
Department of Veterinary Clinical Sciences, Washington State University, Pullman, Washington.
2
Center for Interdisciplinary Statistical Education and Research, Washington State University, Pullman, Washington.
Abstract
BACKGROUND:
Exercise-induced pulmonary hemorrhage (EIPH) is diagnosed and its severity assessed by post-exercise tracheobronchoscopy, and enumeration of bronchoalveolar lavage fluid red blood cells (BALFRBC). Minimal information is available regarding the relationship of tracheobronchoscopy score to BALFRBC number.
OBJECTIVE:
Evaluate the relationship between BALFRBC number and tracheobronchoscopy scores and determine their diagnostic sensitivities.
ANIMALS:
Nine sedentary horses, 21 fit Thoroughbreds, 129 Barrel Racers.
METHODS:
Normal BALFRBC number and the effect of bronchoalveolar lavage (BAL) on it were evaluated by performing 2 BALs 24 hours apart in sedentary horses. Tracheobronchoscopy followed by BAL was performed 247 times on 150 horses after treadmill, racetrack, or barrel racing exercise. Lastly, a BALFRBC diagnostic threshold number that optimized the geometric mean of the sensitivity and precision (F1-score) was determined using Bayesian analysis.
RESULTS:
No increase in BALFRBC occurred after the second BAL (mean ± SD, 304 ± 173/μL). Tracheobronchoscopy scores ranged from 0 (n = 112) to 4 (n = 4) and BALFRBC ranged from 102 to 4605268/μL. Spearman correlation between tracheobronchoscopy score and BALFRBC was weak (P < .001; rs = 0.42) with large ranges of BALFRBC associated with each tracheobronchoscopy score. The highest F1-score occurred for a BALFRBC threshold number = 992/μL. Seventy-five tracheobronchoscopy scores equaled 0 although BALFRBC number was ≥992/μL. Sensitivity of tracheobronchoscopy for diagnosing EIPH was poor (0.59; 95% confidence intervals [CI], 0.49-0.68), compared to BALFRBC number ≥992/μL (0.93; 95% CI, 0.88-0.96). CONCLUSIONS AND CLINICAL IMPORTANCE: False negatives are common with tracheobronchoscopy. Follow-up determination of BALFRBC may be indicated for tracheobronchoscopy scores = 0 before EIPH can be ruled out.