Wassink Guido, Galinsky Robert, Drury Paul P, Gunn Eleanor R, Bennet Laura, Gunn Alistair J
Fetal Physiology and Neuroscience Group, Department of Physiology, University of Auckland, Auckland 1023, New Zealand.
Obstet Gynecol Int. 2014;2014:314159. doi: 10.1155/2014/314159. Epub 2014 Feb 16.
T/QRS ratio monitoring is used to help identify fetal asphyxia. However, immature animals have greater capacity to maintain blood pressure during severe asphyxia, raising the possibility that they may show an attenuated T/QRS increase during asphyxia. Chronically instrumented fetal sheep at 0.6 of gestation (0.6 GA; n = 12), 0.7 GA (n = 12), and 0.8 GA (n = 8) underwent complete umbilical cord occlusion for 30 min, 25 min, or 15 min, respectively. Cord occlusion was associated with progressive metabolic acidosis and initial hypertension followed by severe hypotension, with a more rapid fall in mean arterial blood pressure (MAP) and carotid blood flow (CaBF) with advancing gestation. T/QRS ratio rose after occlusion more rapidly at 0.8 GA than in immature fetuses, to a similar final peak at all ages, followed by a progressive fall that was slower at 0.8 GA than in the immature fetuses. The increase in T/QRS ratio correlated with initial hypertension at 0.8 GA (P < 0.05, R (2) = 0.38), and conversely, its fall correlated closely with falling MAP in all gestational groups (P < 0.01, R (2) = 0.67). In conclusion, elevation of the T/QRS ratio is an index of onset of severe asphyxia in the last third of gestation, but not of fetal compromise.
T/QRS比值监测用于帮助识别胎儿窒息。然而，未成熟动物在严重窒息期间维持血压的能力更强，这增加了它们在窒息期间T/QRS升高减弱的可能性。对妊娠0.6（0.6 GA；n = 12）、0.7 GA（n = 12）和0.8 GA（n = 8）的长期植入仪器的胎羊分别进行30分钟、25分钟或15分钟的完全脐带闭塞。脐带闭塞与进行性代谢性酸中毒以及最初的高血压随后是严重低血压相关，随着妊娠进展，平均动脉血压（MAP）和颈动脉血流（CaBF）下降更快。闭塞后，T/QRS比值在0.8 GA时比未成熟胎儿上升得更快，在所有年龄段最终达到相似的峰值，随后逐渐下降，在0.8 GA时比未成熟胎儿下降得更慢。T/QRS比值的增加与0.8 GA时的初始高血压相关（P < 0.05，R (2) = 0.38），相反，其下降与所有妊娠组中MAP的下降密切相关（P < 0.01，R (2) = 0.67）。总之，T/QRS比值升高是妊娠晚期严重窒息开始的指标，但不是胎儿窘迫的指标。
