ISSN:
1432-2013
Keywords:
Acute Hypoxia
;
Acute Hyperoxia
;
Chronic Hypoxia
;
High Altitude
;
Pulmonary Hypertension
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Hemodynamic studies were done in nine male Holstein calves, born at sea level, at 250 m (P B 740 mm Hg) and in eight of these calves after 2 and 4 weeks at 3400 m altitude (P B 510 mm Hg). Cardiac index (CI) decreased significantly as compared to sea level after 2 weeks at altitude and it was further decreased after 4 weeks. This reduction in CI resulted from decreased stroke index (SI) with unchanged heart rate (HR). Mean pulmonary arterial pressure (PAM) rose from 26 mm Hg at sea level to 63 and 74 mm Hg after 2 and 4 weeks at 3400 m, respectively. Both pulmonary arterial systolic and diastolic pressures were substantially increased at altitude, the diastolic relatively more than the systolic pressure (4.5 fold increase vs. 2.5 fold). Aortic blood pressures (systolic, diastolic and mean) did not change significantly at 3400 m. Right ventricular (systolic) and atrial (mean) pressures increased at altitude. During acute severe hypoxia (P IO 2 55 mm Hg) at sea level CI remained essentially unchanged, while SI and HR, respectively, decreased and rose significantly; PAM was double the normoxic value. Acute hypoxia after 4 weeks at 3400 m did not elicit significant changes in blood gases and pH, CI, SI and HR while PAM increased by 25 mm Hg. There were slight reductions in CI, SI, HR and PAM during acute hyperoxia at sea level. Hyperoxia after 4 weeks at altitude did not change CI, while SI rose significantly; PAM decreased by 30 mm Hg. Apparently, the Holstein calf has a highly reactive pulmonary vascular bed to acute and chronic hypoxia which could make this cattle breed more susceptible to right heart failure during exposure to chronic hypoxia at high altitude.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00592781
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