Premature newborn positionings and physiologic parameters – a randomized clinical study

Abstract Introduction Multiple studies have shown the effects of prone (PP), supine (SP) and kangaroo (KP) positions on clinical and physiological outcomes in preterm newborns, but none compared these three types of positioning between them. Objective To investigate the influence of these positionings on heart rate, respiratory rate, peripheral oxygen saturation (SpO2) and alertness status in clinically stable preterm newborns (NBs) admitted to a neonatal intensive care unit. Methods In a randomized clinical trial, clinically stable NBs with gestational ages from 30 to 37 weeks who were breathing spontaneously were allocated in three positioning groups: PP, SP and KP. Heart rate, breathing frequency, SpO2 and alertness status were evaluated immediately before and after 30 minutes of positioning. Results In all, 66 NBs were assessed (corrected age: 35.48 ± 1.94 weeks; weight: 1840.14 ± 361.09 g), (PP: n = 22; SP: n = 23; KP: n = 21). NBs in the PP group showed a significant improvement in peripheral SpO2 (97.18 ± 2.16 vs 95.47 ± 2.93 vs 95.57 ± 2.95, p = 0.03) compared with the SP and KP groups. Conclusion In clinically stable preterm NBs, the PP was associated with better peripheral oxygen saturation than the SP or KP. In addition, there was a reduction in heart rate within prone position group and in the KP group there was an increase in the number of NBs in the deep sleep classification.


Introduction
Every year, 15 million preterm births are recorded around the world (approximately 1 in every 10 births). 1 Brazil has the tenth highest rate of preterm births (279,300 births per year).This situation is a cause for considerable concern as preterm newborns (NBs) are more likely to develop respiratory complications and experience impaired motor and cognitive development than full-term babies. 2 The conventional approach used with preterm NBs requires a specialized team and specific logistical support, implying greater costs.Mortality among this population is high in low-income regions, and half of babies born at less than 32 weeks of gestation die as a result of inadequate care.Simple, low-cost interventions that improve the quality of care provided represent major advances and can prevent serious, long-term outcomes in these low-income regions.
Various studies of the effects of different positionings for NBs and their clinical and physiological impacts have been undertaken.According to most of these studies, the prone position (PP) has beneficial effects on oxygenation, 3,4 neural development, hemodynamic control and respiratory pattern, and a lower risk of gastroesophageal reflux compared with the supine position (SP).The KP is also associated with important physiological benefits, including restful sleep, improved thermoregulation, and reduced agitation and crying.13 Although several studies provide important evidence of the efficacy of the different positionings considered here, there are, to the authors' knowledge, no studies comparing the effects of the PP, SP and KP nor a consensus on the length of time for which these positions should be used.
In this study we hypothesize the PP will improve peripheral oxygen saturation (SpO  and with SpO 2 level of 89% or more.Each NB's mother was required to be present during the data collection (so that the NB could be assigned to the KP group if necessary).NBs were excluded if they were receiving mechanical ventilation, oxygen (catheter, mask or hood) or palliative care or had undergone abdominal-thoracic surgery, because of which they could not be handled or placed in a particular position.
All the NBs that could potentially be included in the study were recruited by the researchers and, after their parents or legal guardians had signed a voluntary informed-consent form, were included in the study.The

Randomization and allocation concealment
The NBs were allocated randomly to one of three groups using a simple randomization procedure (computer-generated random numbers).The allocation was done with non-transparent, sequentially numbered, sealed envelopes, which were only opened when the random allocation was performed.This procedure was carried out by an independent physical therapist who was not involved in the recruitment, assessment or study interventions.

Calculation of sample size
The outcome chosen to calculate the sample size was The Shapiro-Wilk test was used to determine whether the sample was homogeneous and had a normal distribution.The results are described in terms of the mean and standard deviation and frequency.Baseline characteristics were compared with ANOVA and chi-squared test.To compare the changes between groups, the differences between preintervention and postintervention measures were calculated (Δ = post -pre) for each group and the Bonferroni post hoc test was used when the result was statistically significant.A significance level of p < 0.05 was used.

Results
A total of 82 NBs were recruited for the study, of whom 72 met the inclusion criteria and were well enough to be handled.Each NB was randomly allocated to a group (24 subjects in each group).The final number of NBs included in the study was 66 (PG: n = 22; SG: n = 23; KG: n = 21) (Figure 1) as six participants were excluded because they were scheduled to have routine tests such as X-ray and echocardiogram at the time of the intervention.There were no statistically significant differences in the baseline characteristics between the three groups.
All individuals were in excellent health condition (as observed with the APGAR score), 59% of whom were female (Table 1).We did not observe any adverse effects of the applied interventions.
There was a statistically significant increase in SpO 2 (p = 0.03) in the PP group compared with the SP and KP groups.No statistically significant differences were observed between the groups in terms of HR and RR.
However, there was a significant reduction of 4.54 % in HR within PP group (Table 2).Regarding the alertness status, in the KP group there was a significant increase in the number of NBs in the in the deep sleep classification as well as a reduction in the light sleep/sleepy classification at the post-intervention moment (Table 3).

Conclusion
In preterm newborns, the prone position was associated with better peripheral oxygen saturation than the supine and kangaroo positions.In addition, there was a reduction in HR within prone position group and in the KP group there was an increase in the number of NBs in the deep sleep classification.

2 ,
following data were recorded: sex, gestational age, corrected age and weight at the time of observation, 5-minute Apgar score, length of stay in the ICU and medications administered.The clinical outcome variables SpO HR, RR, and organization of alertness status were recorded before positioning and 30 minutes after positioning.Assessments were performed in the morning, at least one hour after the NBs have been breastfed.SpO 2 and HR were measured simultaneously with a Dixtal DX 2022 multiparameter monitor.RR was measured by an assessor for one minute with a Vollo 500-memory stopwatch.Alertness status assessment at the time of observation was performed based on the Brazelton criteria, 16,17 adapted by Guimarães et al., 18 which comprises four behavioral states: deep sleep; light sleep/sleepy; quiet alert state; agitated/crying state.Assessments were performed in the morning, at least one hour after the NBs have been breastfed.At the beginning of the observation period all the NBs had been monitored and had been resting in the traditional position (lateral decubitus) for at least 30 minutes.19 The data from the assessments before and after each intervention were collected by the same assessor, who had previously been trained.After the initial assessment, the NBs were randomly allocated to one of three groups (PP, SP, KP) and were left in this position for 30 minutes, when they were immediately assessed again.The NBs in the PP group were placed in the prone position with a cushion providing anterior support for their trunk, their head turned to the side and aligned with their torso and the limbs flexed.20 In the SP group, the NBs were placed in the supine position with their heads kept in the center position, their hips and knees kept flexed with a cushion and a U-shaped cushion placed around them for stability.20 Finally, in the KP group, each dry, naked NB was placed on his/her stomach on the mother's bare chest and covered with a warm blanket.21

SpO 2 .
Considering the sample size of a previous study 22 and a post hoc calculation of the power of this study in 84%, using an effect size of 0,77 (Cohen d), sample size was estimated in 21 NBs in each group.After adding 15% of individuals in each group to compensate any sample losses, each group was left with 24 individuals.The sample size was calculated with G*Power 3.1®.Statistical analysis The data were analyzed with Statistical Package for the Social Sciences® version 22.0 for Windows.Fisioter Mov.2023;36:e36102 4

Figure 1 -
Figure 1 -Flowchart of data collection, following CONSORT recommendations.
This is, to our knowledge, the only study to compare simultaneously the effects of the PP, SP and KP in NBs; nevertheless, it suffers from some limitations: 1) the sample size not provided sufficient power to detect a clinically difference in other outcomes (HR, RR and slow wave sleep); 2) since the positioning duration was 30 minutes and one-day technique, the effect of longer-term therapy should be considered; 3) NBs's acceptability and perception of treatment by the mothers was not evaluated; however, due to the very good adherence to the positions, the authors believe that NBs had a positive acceptability; 4) we did not consider the effects of environmental stimuli (noise, lighting and handling) on the NBs, although these could interfere with the results, particularly for the variable slow wave sleep; 4 5) the exclusion of extremely premature patients (< 29 weeks) and using conventional oxygen therapy or noninvasive ventilatory support (NIV, HFNC) may contribute to a limitation of the study, since the results cannot be applied to these preterm infants.Regardless of these limitations, this study has demonstrated the potential usefulness and costeffectiveness of prone positioning for clinically relevant outcomes in preterm infants.This study may also provide information to develop clinical guidelines and recommendations.Large, multi-centered studies are necessary to better define what type of positioning is most beneficial for preterm infants with respiratory distress in ICU and provide evidence-based conclusions about this daily questioning of neonatal ICUs.

Table 1 -
Demographic, anthropometric and clinic characteristics of the study paricipants Note: Data described in terms of the mean ± standard deviation and absolute frequency (n); p-value refers to ANOVA and the chi squared test.PP = prone positioning; SP = supine positioning; KP = kangaroo positioning; ICU = intensive care unit.