Topographic distribution of pulmonary ventilation and perfusion in the horse.
The regional distribution of ventilation to perfusion ratios (VA/Q) in the lungs of 8 healthy standing Thoroughbred geldings (4.4 +/- 1.5 years, 465.7 +/- 46.6 kg) was studied, using steady-state inhalation and IV infusion of the radioactive gas krypton-81m. The VA/Q was uniformly distributed within a vertical lung strip centered over the 9th rib on the right side. Ventilation per unit of alveolar volume (V/VA) assessed from the clearance of inhaled radioactive gas in 5 horses increased from 0.49 +/- 0.13 (arbitrary units) in nondependent lung zones to 1.45 +/- 0.16 in dependent lung zones. Seemingly, a vertical gradient of pulmonary ventilation exists in the horse that is matched by a similar gradient of perfusion.
D000818:Animals; D006339:Heart Rate; D006736:Horses / Q000502:physiology*; D007726:Krypton; D008297:Male; D011652:Pulmonary Circulation; D012123:Pulmonary Ventilation; D011868:Radioisotopes; D013990:Tidal Volume / Q000662:veterinary; D014692:Ventilation-Perfusion Ratio
D011868:Radioisotopes; D007726:Krypton