Levene M I, Shortland D, Gibson N, Evans D H
Department of Child Health and Medical Physics, Leicester University School of Medicine, England.
Pediatr Res. 1988 Aug;24(2):175-9. doi: 10.1203/00006450-198808000-00007.
Little is known about the vasoactivity of cerebral arterioles in extremely premature infants. We have assessed the effects of a small rise in PaCO2 of 1 kPa (7.5 mm Hg) on cerebral blood flow velocity measured by duplex Doppler ultrasound. Nineteen mechanically ventilated infants of 33 wk gestational age or less in whom direct arterial blood pressure monitoring was available, were studied on 45 occasions. There was a close relationship between increasing PaCO2 and increasing cerebral blood flow velocity (p less than 0.005) but on seven of 45 occasions the cerebral blood flow velocity fell with rising PaCO2. There was a 44% (median value) rise in cerebral blood flow velocity per 1 kPa rise in PaCO2 (5.9%/1 mm Hg) in 21 infants tested within 24 h of birth and this increased to a 53% (median value) rise (7%/1 mm Hg) in 20 infants tested after 24 h (p less than 0.001). Eleven infants had paired studies, the first within 24 h and a second at a median age of 48 h. There was a statistically significant increase in percentage reactivity when the later group was compared to those tested within 24 h (p less than 0.001). Carbon dioxide reactivity was also assessed before and after indomethacin infusion (0.2 mg/kg) on four occasions and there was a reduction in reactivity from a median value of 144 to 49.5%, 10 min after indomethacin. The extremely immature, ill infant is less sensitive to a small change in PaCO2 within 24 h of birth and after indomethacin infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
关于极早产儿脑小动脉的血管活性，人们了解甚少。我们通过双功多普勒超声评估了动脉血二氧化碳分压（PaCO₂）小幅升高1 kPa（7.5 mmHg）对脑血流速度的影响。对19例胎龄33周及以下、可进行直接动脉血压监测的机械通气婴儿进行了45次研究。PaCO₂升高与脑血流速度增加密切相关（p<0.005），但在45次研究中有7次脑血流速度随PaCO₂升高而下降。在出生后24小时内接受测试的21例婴儿中，PaCO₂每升高1 kPa，脑血流速度中位数升高44%（5.9%/1 mmHg）；在出生24小时后接受测试的20例婴儿中，这一数值增至53%（中位数）升高（7%/1 mmHg）（p<0.001）。11例婴儿进行了配对研究，第一次在出生后24小时内，第二次在中位年龄48小时时。与出生后24小时内接受测试的婴儿相比，后期组的反应性百分比有统计学显著增加（p<0.001）。还在4个时间点评估了吲哚美辛输注（0.2 mg/kg）前后的二氧化碳反应性，吲哚美辛输注10分钟后，反应性从中位值144%降至49.5%。极不成熟、患病的婴儿在出生后24小时内以及吲哚美辛输注后对PaCO₂的微小变化不太敏感。（摘要截短至250字）
