The effects of perfluorocarbon dosing strategy on cerebral blood flow when starting partial liquid ventilation: A randomized, controlled, experimental study

Introduction: Partial liquid ventilation may benefit the lung disease in preterm neonates but intratracheal instillation of perfluorocarbon increases cerebral blood flow and may cause brain injury. We aimed to determine if the effects of perfluorocarbon administration on cerebral blood flow vary by dose-volume, rate of administration, endotracheal tube portal of entry, or closely targeting PaCO2. Methods: Forty-two dosing events (in eleven rabbits) were randomised to different dosing strategies, including a sham (i.e., placebo/control) dose of air over 20 min, 20 mL/kg of perfluorocarbon slowly over 20 min, 10 mL/kg of perfluorocarbon slowly over 20 min, 10 mL/kg of perfluorocarbon moderately fast over 10 min, 10 mL/kg of perfluorocarbon rapidly over 5 min, 10 mL/kg of perfluorocarbon slowly over 20 min via the endotracheal tube tip lumen (as opposed to the proximal end of the tube used in all other groups), or 10 mL/kg of perfluorocarbon slowly over 20 min whilst targeting a PaCO2 of 45 - 50 mmHg. Blood gases, haemodynamics, cortical cerebral blood flow and carotid flow were recorded continuously for 30 minutes from the start of each dose. Results: Carotid flow increased with 20 mL/kg perfluorocarbon and cortical cerebral blood flow was significantly more variable. Carotid and cortical cerebral blood flow increased using 10 mL/kg or 20 mL/kg with no difference between the two dose-volumes. There was no difference in cerebral blood flow by rate of administration, but carotid blood flow was more variable during slow administration. There were no differences in the increase in cerebral blood flow by portal of entry. If PaCO2 was maintained between 45 - 50 mmHg there was no increase in cerebral blood flow and there was less variable carotid flow. Conclusions: Cerebral blood flow increases with perfluorocarbon dosing. This occurs regardless of the dose-volume of perfluorocarbon. These effects were mitigated by closely targeting PaCO2.

在不确定胎儿心率模式下胎儿产时脉搏血氧定量对剖宫产率的影响:一项多中心、随机、对照试验(FOREMOST试验)

Objective: The objective of the study was to compare operative delivery rates for nonreassuring fetal status between 2 groups of laboring women: those having conventional cardiotocograph monitoring and those having cardiotocograph monitoring plus fetal pulse oximetry. Study design: The intrapartum fetal oximetry prospective, multicenter, randomized, controlled trial (the FOREMOST trial) was conducted in 4 Australian maternity hospitals. The primary outcome was operative birth rates for nonreassuring fetal status. Results: There was a statistically significant 23% relative risk reduction in operative delivery for nonreassuring fetal status in the fetal pulse oximetry + cardiotocograph group (n = 75 of 305, 25% ), compared with those in the cardiotocograph- only group (n = 95/295, 32% )- (relative risk 0.77, 95% confidence interval 0.599, 0.999, P = .048). There were no significant between- group differences in overall operative births (fetal pulse oximetry + cardiotocograph group 73% , cardiotocograph- only group 71% , relative risk 1.04, 95% confidence interval 0.94, 1.15, P = .478) or neonatal outcomes. Conclusion: The use of fetal pulse oximetry to augment fetal well- being assessment during labor resulted in a statistically significant reduction in the operative intervention for nonreassuring fetal status, compared with the use of conventional cardiotocograph monitoring alone. This reduction was achieved with no significant difference in neonatal outcomes.