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Exercise‐induced pulmonary haemorrhage during submaximal exercise
Author(s) -
EPP T. S.,
McDONOUGH P.,
PADILLA D. J.,
GENTILE J. M.,
EDWARDS K. L.,
ERICKSON H. H.,
POOLE D. C.
Publication year - 2006
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.2006.tb05595.x
Subject(s) - medicine , bronchoalveolar lavage , horse , pulmonary artery , cardiology , respiratory system , anesthesia , lung , paleontology , biology
Summary Reasons for performing study: Maximally exercising horses achieve mean pulmonary artery pressures (Ppa mean ) that exceed the minimum threshold (75 mmHg) estimated for pulmonary capillary rupture and exercise‐induced pulmonary haemorrhage (EIPH). EIPH is not expected to occur during moderate submaximal exercise (i.e. 40–60% VO 2max ) since Ppa mean remains well below this threshold. Hypothesis: Prolonged submaximal exercise (trotting) would precipitate locomotory respiratory uncoupling and cause EIPH. This would be present as a result of the most negative intrapleural pressures (as estimated by the minimum oesophageal pressure; Pœs min ) occurring simultaneously with the most positive Ppa (Ppa peak ) to produce estimated maximal pulmonary artery transmural pressures (PATMP max ) that surpass the EIPH threshold. Methods: Five Thoroughbred horses trotted to fatigue (˜25 min) at 5 m/sec on a 10% incline. Ventilation (V E ), Pœs, and Ppa were measured at 5 min intervals, and bronchoalveolar lavage (BAL) red blood cells (RBCs) were quantified 45 min post exercise. Results: BAL revealed an increased EIPH (rest: 2.0 ± 1 times 10 5 , exercise: 17 ± 10 times 10 5 RBCs/ml BALF; P<0.05), despite the highest Ppa mean reaching only mean ± s.e. 55 ± 3 mmHg, while V E , tidal volume and Pœs min approached 70–80% of the values achieved at maximal running speeds (10% incline: 12–13 m/sec) by these same horses. The resulting PATMP max was well above the level considered causative of EIPH. Conclusions: The finding of significant EIPH during submaximal exercise broadens the spectrum of performance horses susceptible to EIPH and supports studies that suggest that extravascular factors are of primary importance in the aetiology of EIPH. Potential relevance: Consideration of strategies such as the equine nasal strip for reducing negative extravascular pressures is warranted even for exercise at moderate intensities.