EFFECTS OF ACUTE HYPOXIA ON HEMODYNAMICS IN DOGS

Abstract

Background: Almost 50 years ago tire proposition that acute hypoxia elicits pulmonary vasoconstriction was made.By now methods have been standardised for exploring the pulmonary and systemic circulation in a systematic &sophisticated way and tire introduction of cardiac catheterization had brought the previous remote pulmonarycirculation within reach. Methods: This study was designed to see the effects of acute hypoxia on hemodynamics withthe advanced, sophisticated equipment and standardised method. The effects of acute 10 minutes’ hypoxia werestudied on hemodynamics in anaesthetized dogs. Results: Acute hypoxia increased the Cardiac Output from 1.76 ±0.43 to 1.91 ± 0.52 L/min. HR from 240 ± 55.58 to 260 ± 63.34 beat/min, Ppa from 2.24 ± 0.61 to 3.39 ± 1.09 kPa,PVR from 9.49 ± 3.33 to 14.30 ± 5.29 kPa. s/L, Psa from 14.53 ± 1.16 to 15.16 ± 1.17 kPa. SVR from 61.50 ± 14.81to 64.33 ± 15.02 kPa. s/L and CBF from i73.62 ± 81.99 to 192.50 ± 85.40 ml/min, respectively. Conclusions: Theresults showed that Acute hypoxia increased all the parameters but the increase in pulmonary vascular resistance wasmore significant than systemic vascular resistance. This shows that in vivo the hypoxic response of cerebral vessel isdilative, while the hypoxic response of pulmonary vessels as well as that of peripheral systemic vessel is constrictive.Key Words: Hypoxia, Hemodynamics.