Cerebral fractional tissue oxygen extraction (cFTOE) during immediate fetal-to-neonatal transition: a systematic qualitative review of the literature.

Cerebral monitoring during immediate fetal-to-neonatal transition is of increasing interest. The cerebral fractional tissue oxygen extraction (cFTOE) is a useful parameter to gain insight in the balance between tissue oxygen delivery and consumption during this complex process. The aim of this study was to review the literature on cFTOE during the first 15 min immediately after birth. A systematic qualitative literature research was last performed on 23 November 2023 of PubMed and EMBASE with the following search terms: neonate, infant, newborn, transition, after birth, delivery room, NIRS, near-infrared spectroscopy, spectroscopy, cFTOE, cerebral fractional tissue oxygenation extraction, cerebral oxygenation, and fractional oxygen extraction. Additional published reports were identified through a manual search of references in retrieved articles and in review articles. The methodological quality of the included studies was assessed by predefined quality criteria. Only human studies with data of cFTOE in the first 15 min after birth were included. Accordingly, exclusion criteria were defined as no measurement of cFTOE or no measurement within the first 15 min after birth. Across all studies, a total of 3566 infants (2423 term, 1143 preterm infants) were analysed. Twenty-five studies were identified describing cFTOE within the first 15 min after birth. Four studies established reference ranges for cFTOE and another four studies focused on the effect of pre-/perinatal circumstances on cFTOE in the first 15 min after birth. Six studies investigated the course of cFTOE after transition in infants without complications. Eleven studies analysed different potentially influencing parameters on cFTOE during transition. CONCLUSION: This systematic review provides a comprehensive insight on cFTOE during uncomplicated transition as well as the influence of perinatal circumstances, respiratory, haemodynamic, neurological, and laboratory parameters in preterm and term infants. WHAT IS KNOWN: • The NIRS-measured cerebral fractional tissue oxygen extraction (cFTOE) is a useful parameter to estimate the balance between oxygen delivery and consumption. • During normal transition, the cFTOE decreases in the first minutes after birth and then remains at a stable plateau. WHAT IS NEW: • The cFTOE is a promising parameter that gives additional information on cerebral oxygenation and perfusion in preterm and term infants. • Several hemodynamic, metabolic, respiratory, and perinatal factors are identified, influencing the oxygen extraction of the newborn's brain after birth.

Cardiac output calculation using the Liljestrand and Zander formula: is this method applicable during immediate transition after birth? - A post hoc analysis.

The transition from intrauterine to extrauterine life is a critical period for neonates. Assessing the cardiovascular transition during this period immediately after birth is crucial but challenging. The present study compares adjusted estimated cardiac output values calculated by the Liljestrand and Zander formula (COest/adj LaZ) with non-invasively measured cardiac output values (CO-bioimpedance) during immediate transition after birth. We performed a secondary outcome analysis of a prospective observational study in preterm and term neonates. Ten and 15 min after birth, arterial blood pressure and heart rate were assessed, and CO-bioimpedance was measured using electrical bioimpedance method (Aesculon monitor, Osypka, Germany). We calculated COest/adj LaZ and compared it to CO-bioimpedance. Further, we performed a correlation analysis. Thirty-two neonates with a median (IQR) gestational age of 37.0 (32.0-39.4) weeks were included. Mean ± SD CO-bioimpedance was 0.62 ± 0.15 l/min, and COest/adj LaZ was calculated to be 0.64 ± 0.10 l/min, whereby both correlated significantly (p = 0.025, r = 0.359) with each other.  Conclusion: The present study demonstrates high comparability of COest/adj LaZ and CO-bioimpedance in neonates during immediate transition after birth, suggesting that cardiac output can be derived in a cost-effective and feasible manner if other methods are not available. What is Known: • Echocardiography is considered the gold standard for non-invasive CO evaluation, but its feasibility during the immediate transition period is limited. What is New: • Non-invasive methods such as CO-bioimpedance for cardiac output (CO) measurement and the Liljestrand and Zander (LaZ) formula for estimating CO offer promising alternatives during the immediate transition period.

Acid base and metabolic parameters of the umbilical cord blood and cerebral oxygenation immediately after birth.

Objective: Aim was to investigate whether acid-base and metabolic parameters obtained from arterial umbilical cord blood affect cerebral oxygenation after birth in preterm neonates with respiratory support and in term neonates without respiratory support. Study design: This was a post-hoc analysis of secondary outcome parameters of a prospective observational study including preterm neonates with and term neonates without respiratory support. Non-asphyxiated neonates with cerebral oxygenation measured with near-infrared spectroscopy during the first 15 min and with blood gas analyses from arterial umbilical cord blood were included. Arterial oxygen saturation (SpO2) and heart rate (HR) were monitored with pulse oximetry. Potential correlations were investigated between acid-base and metabolic parameters (pH-value, bicarbonate, base-excess, and lactate) and crSO2/cFTOE 5 min after birth. Results: Seventy-seven neonates were included: 14 preterm neonates with respiratory support (mean gestational age [GA] 31.4 ± 4.1 weeks; mean birth weight [BW] 1,690 ± 640 g) and 63 term neonates without respiratory support (GA 38.7 ± 0.8 weeks; BW 3,258 ± 443 g). Mean crSO2 5 min after birth was 44.0% ± 24.2% in preterm and 62.2% ± 20.01% in term neonates. Mean cFTOE 5 min after birth was 0.46 ± 0.06 in preterm and 0.27 ± 0.19 in term neonates. In preterm neonates with respiratory support higher lactate was significantly associated with lower crSO2 and SpO2 and tended to be associated with higher cFTOE. In term neonates without respiratory support no significant correlations were found. Conclusion: In non-asphyxiated preterm neonates with respiratory support, lactate levels were negatively associated with crSO2 and SpO2, whereas in term neonates without respiratory support no associations were observed.

The Use of a Disposable Umbilical Clamp to Secure an Umbilical Venous Catheter in Neonatal Emergencies-An Experimental Feasibility Study.

Recent guidelines recommend the umbilical venous catheter (UVC) as the optimal vascular access method during neonatal resuscitation. In emergencies the UVC securement may be challenging and time-consuming. This experimental study was designed to test the feasibility of new concepts for the UVC securement. Umbilical cord remnants were catheterized with peripheral catheters and secured with disposable umbilical clamps. Three different securement techniques were investigated. Secure 1: the disposable umbilical clamp was closed at the level of the inserted catheter. Secure 2: the clamp was closed at the junction of the catheter and plastic wings. Secure 3: the setting of Secure 2 was combined with an umbilical tape. The main outcomes were the feasibility of fluid administration and the maximum force to release the securement. This study shows that inserting peripheral catheters into the umbilical vein and securing them with disposable umbilical clamps is feasible. Rates of lumen obstruction and the effectiveness of the securement were superior with Secure 2 and 3 compared to Secure 1. This new approach may be a rewarding option for umbilical venous catheterization and securement particularly in low-resource settings and for staff with limited experience in neonatal emergencies. However, although promising, these results need to be confirmed in clinical trials before being introduced into clinical practice.