Extravascular lung water in the exercising horse

P. A. Wilkins, R. D. Gleed, N. M. Krivitski, A. Dobson

Research output: Contribution to journalArticlepeer-review


Seven standardbred horses were exercised on a treadmill at speeds (@O12 m/s) producing maximal heart rate, hypoxemia, and a mean pulmonary arterial pressure of @O75 mmHg. Extravascular lung water was measured by using transients in temperature and electrical impedance of the blood caused by a bolus injection of cold saline solution. Lung water was @O3 ml/kg body wt when standing but did not increase significantly with exertion. We conclude that any increase in fluid extravasation from the pulmonary hypertension accumulates in the lung at a level that is less than that detectable by this method. At maximal exertion, the volume of blood measured between the jugular vein and the carotid artery increased by @O8 ml/kg, and the actively circulating component of the systemic blood volume increased by @O17 ml/kg with respect to corresponding values obtained when walking before exertion. These volume increases, reflecting recruitment and dilatation of capillaries, increase the area for respiratory gas exchange and offset the reduced transit times that would otherwise be imposed by the approximately eightfold increase in cardiac output at maximal exertion.

Original languageEnglish (US)
Pages (from-to)2442-2450
Number of pages9
JournalJournal of Applied Physiology
Issue number6
StatePublished - 2001
Externally publishedYes


  • Actively circulating blood volume
  • Blood impedance
  • Central blood volume
  • Double-indicator dilution
  • Temperature

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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