Effects of intravenous aminocaproic acid on exercise-induced pulmonary haemorrhage (EIPH).

Abstract

REASONS FOR PERFORMING STUDY: The antifibrinolytic, 6-aminohexanoic acid, also named aminocaproic acid (ACA), has been used empirically as a treatment for exercise-induced pulmonary haemorrhage (EIPH) on the unsubstantiated basis that transient coagulation dysfunction may contribute to its development. OBJECTIVE: To assess the effect of ACA on bronchoalveolar lavage fluid (BALF) erythrocyte counts in horses performing treadmill exercise at an intensity greater than that needed to reach maximal oxygen consumption. METHODS: Eight Thoroughbreds were exercised to fatigue 3 times on a 10% inclined treadmill at a speed for which the calculated oxygen requirement was 1.15 times VO2max. Horses were treated with a saline placebo, 2 and 7 g ACA i.v. 4 h before exercise, with a crossover design being used to determine the order of the injections. Exercise-induced pulmonary haemorrhage severity was quantified via the erythrocyte count in BALF. Bronchoalveolar lavage fluid was collected 4 h before and 30-60 min post exercise. Results were expressed as mean &#xb1; s.e.m. and analysed by one way repeated measures ANOVA (P < 0.05). RESULTS: Aminocaproic acid administration had no effect on any measured variables (VO2max = 48 &#xb1; 3.0 [C]; 148 &#xb1; 3.0 [2 g ACA]; 145 &#xb1; 3.0 [7 g ACA] ml/kg bwt/min, respectively; run time = 77 &#xb1; 3 [C]; 75 &#xb1; 2 [2 g ACA]; 79 &#xb1; 3 [7 g ACA] seconds, respectively). All horses developed EIPH: 1691 &#xb1; 690 vs. 9637 &#xb1; 3923 (C); 2149 &#xb1; 935 vs. 3378 &#xb1; 893 (2 g ACA); 1058 &#xb1; 340 vs. 4533 &#xb1; 791 (7 g ACA) erythrocytes/&#xb5;l pre- vs. post exercise recovered in BALF, respectively. CONCLUSION: Aminocaproic acid was not effective in preventing or reducing the severity of EIPH or improving performance under the exercise conditions of this study.