Sladek M, Parker R A, Grŏgaard J B, Sundell H W
Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2585.
Pediatr Res. 1993 Dec;34(6):821-8. doi: 10.1203/00006450-199312000-00025.
The effect of prolonged hypoxemia (H) after birth on the evolution of the ventilatory response to changes in arterial partial pressure of O2 was determined in unanesthetized, awake lambs. H was induced for 12 d after birth in seven lambs through exposure to 0.10 fraction of inspired O2 (FiO2). Five control (C) lambs were kept in 0.21 FiO2. The ventilatory response (percent increase from baseline) to acute hypoxia was tested with 0.14 FiO2 and 0.10 FiO2. The tonic activity of the peripheral chemoreceptors was assessed by the transient pure oxygen inhalation test (Dejours' test). The occlusion technique was used to measure the baseline neuromuscular drive of breathing. A markedly decreased early ventilatory response to acute hypoxia persisted in the H lambs for at least 5 wk after termination of H compared with the C group. The second phase of the response was significantly lower only at 12 d (the end of H) and was thereafter comparable to that in the C lambs. The ventilatory response to hyperoxia was significantly lower in the H lambs only at the end of hypoxemia at 12 d and rapidly normalized after return to normoxia. H did not significantly affect resting neuromuscular drive. These results show that postnatal maturation of the ventilatory response to changes in arterial partial pressure of O2 can be delayed by prolonged postnatal hypoxemia. The effect on the response to hyperoxia is transient, whereas the response to acute hypoxia is affected for an extended time. This study illustrates the importance of an adequate postnatal arterial partial pressure of O2 for the development of the ventilatory response to acute hypoxia.
在未麻醉的清醒羔羊中，研究了出生后长期低氧血症（H）对动脉血氧分压变化时通气反应演变的影响。通过暴露于0.10的吸入氧分数（FiO2），在七只羔羊出生后诱导低氧血症12天。五只对照（C）羔羊饲养在0.21 FiO2环境中。用0.14 FiO2和0.10 FiO2测试对急性低氧的通气反应（相对于基线的增加百分比）。通过短暂纯氧吸入试验（德茹尔试验）评估外周化学感受器的紧张性活动。采用闭塞技术测量呼吸的基线神经肌肉驱动。与C组相比，H组羔羊在低氧血症终止后至少5周内，对急性低氧的早期通气反应明显降低。反应的第二阶段仅在12天（低氧血症结束时）显著降低，此后与C组羔羊相当。仅在12天低氧血症结束时，H组羔羊对高氧的通气反应显著降低，恢复正常氧合后迅速恢复正常。低氧血症对静息神经肌肉驱动无显著影响。这些结果表明，出生后长期低氧血症可延迟对动脉血氧分压变化的通气反应的产后成熟。对高氧反应的影响是短暂的，而对急性低氧的反应在较长时间内受到影响。本研究说明了出生后充足的动脉血氧分压对急性低氧通气反应发育的重要性。
