The pathogenesis of pulmonary hypertension syndrome (PHS, ascites) includes the development of systemic arterial hypoxemia (reduction in the saturation of hemoglobin with O2, HbO2), which can be mimicked in clinically healthy broilers by i.v. injections of microparticles (MP). In experiment 1, arterial blood samples were collected from clinically healthy broilers before and after i.v. MP injections, and during a subsequent 100% O2 inhalation period. The arterial samples were analyzed for HbO 2, partial pressure of O2 and CO2, and pH using a blood gas analyzer. In experiment 2, broilers that initially averaged ≥75% HbO2 were assigned to a "high O2" group, whereas those that initially averaged <75% HbO2 were assigned to a "low O2" group. The HbO2 and heart rate (HR) were measured using a pulse oximeter before, during, and after broilers in both groups inhaled 100% O2. In experiment 3, HbO2 and HR were measured using a pulse oximeter before, during, and after broilers inhaled 100% O2, after i.v. MP injections, and during a second period of 100% O2 inhalation. The HbO2 rapidly decreased after i.v. MP injections, and subsequently providing 100% O2 to breathe increased the HbO2 above preinjection control levels in experiments 1 and 3. In experiment 2, inhaling 100% oxygen eliminated the initial spontaneous differences in HbO2 between the high O2 and low O 2 groups, whereas the return to breathing ambient air restored the initial group differences in HbO2. These experiments indicate that MP-induced and spontaneous hypoxemia can be attributed to a diffusion limitation rather than to arterial-venous shunts, because the hypoxemia resulting from arterial-venous shunts cannot be wholly eliminated by providing 100% O 2 to inhale.
All Science Journal Classification (ASJC) codes
- Animal Science and Zoology