Relationship between tracheobronchoscopic score and bronchoalveolar lavage red blood cell numbers in the diagnosis of exercise‐induced pulmonary hemorrhage in horses

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 BAL-FRBC 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).Abbreviations: BAL, bronchoalveolar lavage; BALFRBC, bronchoalveolar lavage fluid red blood cell number; EIPH, exercise-induced pulmonary hemorrhage; PBS, phosphate-buffered saline; RBC, red blood cells; ROC, receiver operating characteristic; TBE, tracheobronchoscopic examination.

Physiologic effects of furosemide in combination with water restriction when administered at 4 and 24 hours prior to high‐intensity treadmill training

“…This is not unexpected as it has been well established that most horses undergoing strenuous exercise have some degree of bleeding (Erickson, 1994). Furthermore, it has been suggested that horses ultimately diagnosed with EIPH using methods, such as quantitation of RBCs in BAL fluid, do not necessarily have signs of hemorrhage on endoscopic examination (Hinchcliff, McKeever, & Muir, 1991; Lester et al., 1999; Sanchez, Kogan, Gold, Sellon, & Bayly, 2020).…”

Cytologic Scoring of Equine Exercise-Induced Pulmonary Hemorrhage (EIPH): Performance of Human Experts and a Deep Learning-Based Algorithm

“…15 This method is relatively easy to perform and seems to have a very high specificity. 18 However, sensitivity was estimated to be only 59% (many false negative diagnoses) when compared to RBC content in respiratory fluid cells. 18 Therefore, it has been proposed that a lack of tracheobronchoscopic evidence of blood cannot be used to rule out EIPH.…”

“…30 As compared to tracheobronchoscopy, those tests are generally assigned a higher sensitivity and many authors have recommend these as the best available diagnostic tests. 13,16,18,28,33,34 Whereas RBC counts can only be used to diagnose a recent EIPH episode within a few hours to days, increased hemosiderin content in alveolar macrophages (i.e. hemosiderophages) may reveal less recent EIPH episodes.…”

“…18 However, sensitivity was estimated to be only 59% (many false negative diagnoses) when compared to RBC content in respiratory fluid cells. 18 Therefore, it has been proposed that a lack of tracheobronchoscopic evidence of blood cannot be used to rule out EIPH. 18,28 Diagnosis of EIPH through examination of respiratory tract fluids has been derived from the RBC content, 18,30 hemosiderin content in alveolar macrophages, 11,13 or less commonly hemoglobin concentration.…”

“…18 Therefore, it has been proposed that a lack of tracheobronchoscopic evidence of blood cannot be used to rule out EIPH. 18,28 Diagnosis of EIPH through examination of respiratory tract fluids has been derived from the RBC content, 18,30 hemosiderin content in alveolar macrophages, 11,13 or less commonly hemoglobin concentration. 30 As compared to tracheobronchoscopy, those tests are generally assigned a higher sensitivity and many authors have recommend these as the best available diagnostic tests.…”