Zugaib M, Forsythe A B, Nuwayhid B, Lieb S M, Tabsh K, Erkkola R, Ushioda E, Murad S, Brinkman C R, Assali N S
Am J Obstet Gynecol. 1980 Oct 15;138(4):453-8. doi: 10.1016/0002-9378(80)90145-3.
The effects of acute hypoxia on the resting arterial pressure as well as on heart rate and its beat-to-beat variability were studied in chronically instrumented, unanesthetized newborn lambs at 2 to 8 weeks of neonatal life. Lung ventilation with a gas mixture containing 10% oxygen and 3% carbon dioxide decreased arterial blood PO2 by about 50% in all animals regardless of age without significantly altering blood pH and PCO2. This degree of hypoxia produced a mild pressor response, accompanied by a significant tachycardia; the pattern of these changes, however, differed somewhat according to neonatal growth. The impact of hypoxia on beat-to-beat variability of the neonatal heart rate also varied with age. When the lambs were 2 to 3 weeks old, both the long- and short-term variabilities decreased progressively during hypoxia and the decrement reached a maximum at 10 minutes of oxygen deprivation. As the lambs became older, however, there was some initial and transient increase in the long- and short-term variabilities in the early period of hypoxia but thereafter the changes were inconsistent. The significance of these observations is discussed in terms of our knowledge of the pathophysiologic alterations in the cardiovascular system produced by acute hypoxia.
在出生后2至8周的慢性植入仪器、未麻醉的新生羔羊中，研究了急性缺氧对静息动脉压以及心率及其逐搏变异性的影响。用含10%氧气和3%二氧化碳的混合气体进行肺通气，在所有动物中，无论年龄大小，动脉血PO2均降低约50%，而血液pH值和PCO2无显著变化。这种程度的缺氧产生了轻度的升压反应，并伴有明显的心动过速；然而，这些变化的模式根据新生儿的生长情况略有不同。缺氧对新生儿心率逐搏变异性的影响也随年龄而变化。当羔羊为2至3周龄时，缺氧期间长期和短期变异性均逐渐降低，在缺氧10分钟时降低幅度达到最大。然而，随着羔羊年龄的增长，缺氧早期长期和短期变异性会有一些初始的短暂增加，但此后变化并不一致。根据我们对急性缺氧引起的心血管系统病理生理改变的了解，对这些观察结果的意义进行了讨论。
