Porras H, Meehan B, Côté A
Division of Respiratory Medicine, Montreal Children's Hospital-Research Institute, McGill University, Canada.
Pediatr Res. 1995 Dec;38(6):926-31. doi: 10.1203/00006450-199512000-00016.
Theophylline, a drug frequently used in newborns, stimulates respiration and increases the metabolic rate in a sustained fashion; hypoxemia, on the other hand, decreases metabolic rate and increases ventilation slightly and, at times, only transiently. This study looked at the effect of theophylline on the metabolic and ventilatory response to hypoxemia in piglets. We studied two groups of piglets during normoxia and hypoxemia: first during a baseline period; and second, after the infusion of either theophylline or a placebo. All studies were done in quiet sleep, 2 d after instrumentation was performed to place vascular catheters and electroencephalographic electrodes. O2 consumption (VO2) and CO2 production (VCO2) were measured in a metabolic chamber, and alveolar ventilation (VA) was then derived from VCO2 and PaCO2. We found that theophylline did not abolish the small decrease in oxygen consumption brought about by hypoxemia. Nor did theophylline augment the ventilatory response to hypoxemia. In fact, the percent change in alveolar ventilation decreased slightly: going from 17 +/- 8% during the baseline period to 9 +/- 6% (p < 0.005) after theophylline administration. We found a significant increase in respiratory exchange ratio (R) in response to hypoxemia (from 0.87 +/- 0.05 to 0.97 +/- 0.04, p < 0.001). However, after the administration of theophylline, additional exposure to hypoxemia did not result in a change in R. In summary, our results show that, in sleeping newborn piglets, theophylline does not abolish the decrease in oxygen consumption observed in response to hypoxemia; nor does it enhance the ventilatory response to a moderate degree of hypoxemia.
氨茶碱是新生儿常用药物，可刺激呼吸并持续提高代谢率；另一方面，低氧血症会降低代谢率，轻微增加通气量，且有时仅为短暂增加。本研究观察了氨茶碱对仔猪低氧血症时代谢和通气反应的影响。我们在常氧和低氧状态下研究了两组仔猪：首先是在基线期；其次是在输注氨茶碱或安慰剂之后。所有研究均在安静睡眠状态下进行，在置入血管导管和脑电图电极的仪器操作2天后开展。在代谢舱中测量氧耗量（VO2）和二氧化碳生成量（VCO2），然后根据VCO2和动脉血二氧化碳分压（PaCO2）得出肺泡通气量（VA）。我们发现，氨茶碱并未消除低氧血症引起的氧耗量小幅下降。氨茶碱也未增强对低氧血症的通气反应。事实上，肺泡通气量的百分比变化略有下降：从基线期的17±8%降至氨茶碱给药后的9±6%（p<0.005）。我们发现，低氧血症会使呼吸交换率（R）显著升高（从0.87±0.05升至0.97±0.04，p<0.001）。然而，给予氨茶碱后，再次暴露于低氧血症并未导致R值发生变化。总之，我们的结果表明，在睡眠中的新生仔猪中，氨茶碱并未消除低氧血症时观察到的氧耗量下降；也未增强对中度低氧血症的通气反应。
