孕羊低温体外循环对胎羊体温及血流动力学的影响

Effect of maternal hypothermic cardiopulmonary bypass on fetal hemodynamics

目的探讨孕羊低温体外循环(hypothermic cardiopulmonary bypass,CPB)对胎羊血流动力学的影响。方法孕羊20头,随机分成4组:对照组,开胸不建立体外循环;CPB组再分为常温组、浅低温组和中低温组,建立常规体外循环,转流降温、复温30min。分别监测孕羊和胎羊的体温、心率、平均动脉压,胎羊脐动脉、降主动脉和颈内动脉的搏动指数(pulse index,PI)。结果孕羊体温变化快于胎羊体温变化;在CPB组中,不同时间点温差为0.2～2.4℃。胎羊心率在CPB开始时一过性增快,但随母体体温下降逐渐下降,复温后心率能恢复至基础水平;孕羊和胎羊平均动脉压差异无统计学意义(P>0.05)。浅低温组和中低温组颈内动脉PI值较对照组和常温组显著增高(P<0.05),脐动脉PI值组间差异无统计学意义,但随体外循环时间的延长而增高。结论胎羊体温变化与孕羊同步,孕羊CPB降温时,胎羊心率明显下降,复温后胎羊心率能回复正常,体外循环对胎羊平均动脉压无明显影响,但低温降低胎羊颈内动脉和脐动脉的血流。

Objectives To evaluate effect of maternal hypothermic cardiopulmonary bypass on fetal hemodynamics. Methods Twenty ewes were divided into four groups randomly：control group （n =5）, normothermic group （n=5）, mild hypothermic group （n=5） and moderate hypothermic group （n=5）. Thoracotomy were done without cardiopulmonary bypassc （CPB） in control group; CPB were built up with different temperature. Fetal and maternal temperatures, heart rates, mean BPs, pulse index of fetal umbilical artery, descending aorta and internal carotid artery were evaluated at cooling and wanning stages. Results The change of temperature of ewes was faster than the one of fetuses. The former was active. In the three CPB groups, the gradient of temperature between ewe and fetus was small, with the maximal mean gradient 2.4℃ and the minimal mean gradient 0.2℃. In the fetus, the start of CPB and cooling was associated with the decrease of maternal temperature. Fetal heart rate rapidly increased during the rewanning phase, coming back to basal values. There were no difference of mean BPs of ewes and fetal lambs between the different groups （P〉0.05）. CA PI value of mild hypothennic group and moderate hypothennic group were markedly higher than those of control group and nonnothennic group （P〈0.05）. There was no difference of UA PI value in the four groups, but PI value increased following the prolonged duration of CPB. Conclusions The change of temperature of ewes is active; the timing between ewe and fetus is excellent. Cooling of maternal bypass makes the decrease of fetal heart rate markedly, and fetal heart rate recovers to basal value following the rewarming phase. There were no marked effect of CPB on fetal mean BPs, however CPB impacted on blood flow of fetal brain and umbilical artery.