ABSTRACT

According to delivery room guidelines, an optimal position is not specified for the stabilization of the baby. This study aimed to define the positions effects on postnatal adaptation parameters and cerebral oxygenation in non-resuscitated neonates.

A total of 60 neonates delivered by cesarean section stabilized randomly in the supine, right-side, left-side, or prone positions were enrolled. Apgar scores, heart rates (HR), arterial oxygen saturations via pulse oximetry, and perfusion indexes (PI) at the 2^nd, 5^th and 10^th minutes were recorded. Cerebral regional oxygen saturation (SpO₂) of the patients was monitored by near-infrared spectroscopy.

In the prone position, the 1^st minute Apgar score was significantly lower than other groups, but no difference was observed at the 5^th minute Apgar scores (1^st min Apgarprone, p=0.05). Although there was no statistically significant difference, the prone position had the lowest HR at the 2^nd minute, while the supine posture had the greatest HR at the 5^th and 10^th minutes. While the groups’ SpO₂ values were similar, the left-side group’s perfusion rates increased at the 5^th and 10^th minute marks (5^th and 10^th min PIleft-side, p=0.67, p=0.21, respectively). Regional cerebral oxygen saturation (rScO₂) and cerebral fractional oxygen extraction did not differ significantly between groups at the 5^th and 10^th minute time intervals. Although right and left rScO₂ were found to be higher in the first 5 minutes in the prone position, this elevation did not lead to a statistically significant difference, and right and left rScO₂ values were found to be similar in all groups at the 10^th minute.

Adaptation parameters were not affected by position, except for lower 1^st minute Apgar scores in the prone group and higher perfusion indices in the left lateral position. Cerebral perfusion was similar in all groups. The left-side position, which results in a higher PI, may be a good alternative. Studies with larger case series may provide further information.

Introduction

For postnatal adaptation, the first “golden hour”, and especially the first “golden minute”, after birth are very important. In the delivery room, routine care and resuscitation of newborn infants should adhere to international management guidelines (1, 2). Although these are very detailed, it is unclear which position is optimal for the baby immediately after birth. The 2000 Neonatal Resuscitation Program (NRP) guidelines suggested that a supine or lateral position was appropriate (3), but these recommendations were excluded from the updated guidelines (1, 2, 4, 5).

In neonates, the position of the body may affect cardiopulmonary functions (6). Positions other than the supine position can provide a faster rising heart rate (HR), easier cleaning of airway secretion, and therefore possibly better cerebral oxygenation (7). Several papers on the newborn’s cord clamping time and the necessity of non-invasive breathing have been published in the literature which look at how position affects cerebral regional oxygenation and hemodynamic changes (8, 9). When delayed cord clamping occurred after birth, there was no discernible difference in hematocrit between the supine and prone positions at the 30-hour mark. However, prone positioning was observed to increase arterial and cerebral oxygenations in preterm babies undergoing nasal non-invasive ventilation (NIV) for mild-to-moderate respiratory distress.

The Apgar score, developed by Virgina Apgar in 1953, is the most widely used instrument for evaluating a neonate (10). This clinical score takes into account breathing, muscular tone, skin tone, HR, and reflex irritation. However, there are significant inter-observer fluctuations with this score (11). More cardio vascular monitoring could mitigate this restriction. The most recent guidelines for the assistance of baby transition and resuscitation from the European Resuscitation Council recommended employing electrocardiography (ECG) and/or pulse oximetry to check HR as the only cardio circulatory monitoring in the delivery room (12). To assess the neonate’s cardio-circulatory state, HR may not be sufficient on its own. Furthermore, cardiac output (CO) may be an important variable in the first few weeks following birth. Thermodilution is the gold standard method for obtaining CO, however its utility and viability in the neonatal population are limited. Thus, the primary purpose of echocardiography in this population is to evaluate CO. However, during the immediate transition period, this is not a practical approach. When echocardiography is combined with cerebral-regional-oxygen-saturation, which may be measured using near-infrared spectroscopy (NIRS), it is useful in evaluating cardio-circulation as well as cerebral autoregulation (13). Delivery and consumption of oxygen are necessary for NIRS measurements. The arterial oxygen saturation (SpO₂), brain perfusion, and hemoglobin concentration of the blood all influence the amount of oxygen given. For cerebral perfusion, systemic vascular resistance and CO are required, as well as brain vascular resistance and cerebral perfusion pressure.

The present study assessed the impact of four different positions, namely supine, right-side, left-side, and prone, on cerebral oxygenation and postnatal adaptability while stabilizing newborns who did not require resuscitation.

Materials and Methods

This study, which lasted two months and was conducted in the delivery room of the department of obstetrics and gynecology by the newborn department, where about 3,500 babies are born every year, was prospective, randomized, and observational. Stabilization was carried out in compliance with NRP guidelines by three pediatric residents and a neonatologist who was certified by the NRP. The study participants were babies with Apgar scores greater than 7 and those who were single, term, and appropriate for gestational age (GA) and did not require resuscitation. Only infants delivered by cesarean section (CS) and who were unable to have early skin-to-skin contact were included, while vaginal births were excluded. Babies with major congenital anomalies, preterm infants, and those requiring positive pressure ventilation were excluded from this study.

The women who were about to undergo CS were placed under spinal anesthesia; oxygen therapy was not started before the baby was delivered. Written consent was acquired and the parents were informed about this study before the baby was born. After the inclusion criteria were met, randomization was performed, and closed-envelope randomization was applied. The infants (15 in each group) were positioned supine, on the right or left side, or prone after randomly opening envelopes with positional codes.

Infant Positioning

When the baby was born, the first care was carried out under a radiant heater. Those babies who required positive pressure ventilation were placed in a supine position and removed from the study population.

Medical Records and Vital Parameters

Thirty seconds after delivery, each evaluation began, and they ended after 10 minutes. The same individual scored each infant’s Apgar scores at the first and fifth minutes. They also recorded the infant’s HR, SpO₂, and perfusion index (PI) pulse oximetry at the second, fifth, and tenth minutes using a Masimo Radical-7 pulse co-oximeter. The difference in change between the mean values were assessed. After positioning the probe preductally (on the right wrist), the oximeter was attached to it. During every stabilization period, the fraction of inspired oxygen was only 0.21, or “room air”. The NRP 2015 recommendation states that aspiration should not be carried out in the delivery room on a regular basis. The number of requirements and duration of tactile stimuli were recorded.

Cerebral Oxygenation

Cerebral oxygenation was assessed using noninvasive NIRS; a Covidien INVOS 5100C device was used to record the mean values at the five and ten-minute marks (14-16). The NIRS sensors were disposable and designed for single-use. Therefore, a separate NIRS probe was used for each patient, following the company’s instructions. The NIRS probe was positioned on either side of the frontal lobe.

The baseline value was the first measured value. Regional cerebral oxygen saturation (rScO₂) variations were then collected for 60 seconds at 2-second intervals, and the mean value was computed. Normally, the rScO₂ ranges from 50 to 80%, but it can fluctuate by 10 to 20% at any time (17). Cerebral ischemia is indicated by a reduction of more than 20% in patients whose basal cerebral rScO₂ value is greater than 50%, and a decrease of more than 15% in patients whose basal cerebral rScO₂ value is less than 50% (18). After application, data were gathered for ten minutes at a rate of 0.1 Hz for each position. In an animal model, cerebral fractional oxygen extraction (cFOE), which represents the equilibrium between oxygen delivery and consumption in the tissue, was computed as (SpO₂-rScO₂)/SpO₂ for each position for the 5^th and 10^th minute averages (19).

No financial support was obtained for this study.

Statistical Analysis

The analysis of the variables was conducted using the programs PAST 3 (Hammer, Harper, D.A.T., Ryan, P.D. 2001. Paleontological Statistics) and SPSS 25.0 (IBM Corporation, Armonk, New York, United States). The Levene test was used to assess homogeneity of variance, while the Shapiro-Wilk-Francia test was used to assess conformance of univariate data to the normal distribution. The homogeneity of variance was assessed using the Box-M test, and the conformance of multivariate data to the normal distribution was assessed using the Mardia (Dornik and Hansen Omnibus) test. Post-hoc analyses were conducted using Dunn’s test; the Kruskal-Wallis H test, a non-parametric parametric method, was applied to the Monte Carlo simulation results; and Fisher’s Least Significant Difference tests were utilized for one-way ANOVA post-hoc analysis when comparing more than two groups based on quantitative data. The Fisher-Freeman-Holton test was used to compare categorical variables with one another using the Monte Carlo Simulation method. Categorical variables are given as n (%) in the tables, while quantitative variables are expressed as mean (standard deviation) and median (25^th percentile/75^th percentile). The variables were examined with a 95% confidence level, and a p-value of less than 0.05 was accepted as significant.

Results

We recorded 178 live births evaluated by the same delivery room team for 2 months. We included only cesarean-born infants. Totally, 118 infants were excluded from this study, of whom 87 were vaginally born, 22 were preterm, 3 had major congenital anomalies, and 6 required positive pressure ventilation (Figure 1). All other infants were placed in their assigned positions. All groups were similar in terms of gestational weeks and birth weight (Table I). There were no significant differences among the groups in terms of their requirements for aspiration or tactile stimulation (Table I). In the prone position group, the 1^st min Apgar score, especially the grimace “reflex response” score, was significantly lower than those of the other groups [1^st min Apgar score_median, supine: 9 (8/9), prone: 8 (8/9), right-side: 9 (8/9), left-side: 9 (9/9); p=0.05] (Table II). The 5^th minute Apgar scores were similar in all groups (Table II). The 2^nd minute HR was the lowest in the prone position; the 5^th and 10^th min HRs were highest in the supine position, but there was no statistically significant difference [2^nd min HR, prone: 131 (126/145); p=0.53, 5^th and 10^th min HR, supine: 168 (153/176); p=0.37, 170 (152/179); p=0.17, respectively] (Table II). The SpO₂ values did not differ between the groups, the 5^th and 10^th minute perfusion rates were higher in the left-side group [5^th and 10^th min PI, left-side: 3.6 (2.6/4.7); p=0.67, 4.1 (3.5/5.6); p=0.21, respectively] (Table II). There was no significant difference between the groups in terms of cerebral oxygenation as measured by rScO₂ and cFOE at 5^th and 10^th min [left_rScO2, p=0.39, right_rScO2, p=0.13, left_cFOE, p=0.58, right_cFOE, p=0.68] (Table III). Although right and left rScO₂ in the prone position did not demonstrate a statistically significant difference, it was found to be higher at the 5^th minute [5^th min rScO₂ in the prone position, left frontal: 76.40 (8.80); p=0.75, right frontal: 77.27 (10.85); p=0.51, respectively], and the right and left rScO₂ values at the 10^th minute were similar in all groups [10^th min rScO₂ in all positions, left frontal; p=0.97, right frontal; p=0.84]. None of the study infants required further resuscitation. However, following stabilization, one infant in the supine position and one infant in the right-side position developed respiratory distress. The respiratory distress of the infant in the supine position regressed within 1 hour, and the baby was the given to the mother. However the other infant in the right-side position group had to be transported to the neonatal intensive care unit.

Discussion

The international delivery room management guidelines do not give clear information on the initial lying position of those infants who do not require resuscitation. Although positioning may affect cerebral oxygenation in neonates, there are very few studies investigating the effect of positioning on cerebral oxygenation.

The mixed tissue saturation value that cerebral rSO₂ provides allows information on the equilibrium between brain oxygen delivery and oxygen usage. Cerebral rSO₂ is affected by cerebral blood flow, hemoglobin concentration, and SpO₂ (20-22). When contrasted with SpO₂ levels or HR, rScO₂ rises and achieves a plateau during the fetal-to-neonatal transition considerably more quickly, suggesting that the brain may receive preferential oxygen delivery (20). The burden of cerebral hypoxia was found to be reduced in the rScO₂+SpO₂ group when decisions about providing extra oxygen to newborns during the first 15 minutes after delivery were made based on rScO₂+SpO₂ rather than SpO₂ alone (23). Therefore, during immediate transition and resuscitation after birth, rScO₂ monitoring to guide respiratory and supplemental oxygen support is feasible.

In our study, there were no differences between the groups in terms of rScO₂, cFOE, and SpO₂ in different lying positions in healthy newborns who did not need resuscitation. In certain studies where infants requiring resuscitation were included, differences in NIRS values according to position were observed.

Stabilization in the lateral or prone positions allows for the easy removal of secretions and better oxygenation (24). In both animal studies and adult intensive care patients, arterial blood oxygenation was better when infants were placed prone (25-28). In premature infants receiving NIV, Barsan Kaya et al. (29) showed that prone positions improved arterial and cerebral oxygenations more than supine positions. In severely preterm newborns (GA 24-28 weeks) at one week of age, Shepherd et al. (30) found increased cerebral FOE but no change in rScO₂ and higher SPO₂ values in the prone position during active and calm sleep, suggesting lower cerebral blood flow. Despite the fact that the prone position may increase oxygenation by enhancing the ventilation/perfusion ratio, it is difficult to evaluate the baby’s color, HR, reflex response, muscle tone, and respiration rate in this position.

There were no differences in the HR and SpO₂ parameters between the positions in our study. In the prone position, the grimacing reflex response and the 1^st minute Apgar score was lower, and the need for tactile stimulation was non-significantly higher, but the statistical difference in Apgar scores between the groups disappeared by the 5^th minute. O’Donnell et al. (11) compared the supine and left lateral positions during postnatal adaptation in 82 preterm infants born <32 gestational weeks, and those in the left lateral position respired more effectively as measured by 5^th minute pulse oximetry (11). Konstantelos et al. (7) found that babies stabilized in the lateral position were less agitated than those in the supine position as SpO₂ and HR increased more rapidly in these infants.

The pulsatile-to-static blood flow ratio in peripheral tissue, known as PI, is largely based on the volume of blood present at the monitoring point and significantly correlates with left ventricular output in healthy infants (31). Another study conducted in the Republic of Korea evaluated the association between hemodynamic parameters and left ventricle position in a pig model during cardiopulmonary resuscitation. Their results showed that there were substantial relationships between the two (32). In our study, the 5^th and 10^th minute PI values were insignificantly higher in the left-side lying group. This finding may be related to increased left ventricular CO in the left-sided position. These effects of left- or right-side positioning need to be confirmed by further studies with larger series.

Study Limitations

To date, this was the first study evaluating the effects of position on cerebral oxygenation in healthy-term infants who did not need resuscitation during the transition period in the delivery room. The limitations of this study were its small number of study patients and the use of pulse oximetry instead of ECG in the delivery room. We preferred pulse oximeter measurements to enable a comparison with cerebral oxygenation measurements with NIRS. The third limitation was the impossibility of performing a blind intervention due to the nature of this study.

Conclusion

We found no significant major effects of the initial lying position on postnatal adaptation parameters or cerebral oxygenation during the first 10 minutes of life in term newborns who did not require resuscitation. Only the 1^st minute Apgar score was lower in the prone position, but no difference was observed for 5^th minute Apgar scores between the groups. The left-side position, which resulted in a higher PI, may be a good alternative. Studies with larger case series may provide further information on this issue.