A clinical scoring system to predict the need for extensive resuscitation at birth in very low birth weight infants

Most newborn infants make the transition from intrauterine to extrauterine life without difficulty. About 10% need some assistance, and fewer than 1% require cardiac compression or medication in the delivery room [1]. However, among very low birth weight (VLBW) infants, approximately 90% need some kind of resuscitation and 4–10% require cardiac compression or medication [2‐5].

The 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommend that every birth be attended by at least one person, and that additional personnel with full resuscitation skills should be immediately available for infants with significant perinatal risk factors that increase the likelihood of needing resuscitation [1]. Since most VLBW infants need positive pressure ventilation, two individuals usually attend these deliveries. In addition, when using extensive resuscitation, such as cardiac compression and epinephrine, at least three well-trained personnel, and needed resuscitation equipment and supplies are required.

Medical resources differ between countries and hospitals, as well as at different times of day and days of the week. Although the individual team members may have mastered the skills to resuscitate a newborn, they will not be able to use their skills optimally unless they work together as a team. Therefore, it is useful to be able to predict the need for resuscitation earlier than immediately prior to delivery, in order to save medical resources, especially in hospitals where they may be limited. Thus, our goal for this study was to establish a clinical prediction model, and to identify the antenatal risk factors associated with requiring extensive resuscitation in VLBW infants.

The study sample was 5298 VLBW infants (Fig. 1). A total of 5904 VLBW infants were registered in the KNN database during the study period. Among these, 15 infants had no recorded resuscitation, 44 infants were missing data for premature rupture of membrane, 521 infants were missing data for amniotic fluid, and 117 infants were missing data for antenatal steroid use. As some infants were missing more than one data, 606 infants were excluded and therefore, the final sample was 5298 VLBW infants. Extensive resuscitation occurred in 260 (4.9%) of these cases.

This is the first study to establish a prediction model for extensive delivery room resuscitation in VLBW infants. The model showed fair predictive accuracy.

Few previous studies have explored predictions of the need for neonatal resuscitation [7‐10]. Aziz et al. found that maternal hypertension, maternal infection, multiple pregnancy, and oligohydramnios are independent risk factors for requiring positive pressure ventilation and/or endotracheal intubation. Their study included infants at 23 to 42 weeks’ gestational age and 9% were < 36 weeks [8]. A study by Afjeh et al. with a sample of infants with mean gestation of 37.4 weeks of whom 23.7% were preterm showed that low birth weight, meconium-stained fluid, and chorioamnionitis are independent risk factors for requiring endotracheal intubation [7]. However, it was unclear whether chorioamnionitis in their study was clinically and/or histologically based. In the current study, histologic chorioamnionitis was associated with extensive resuscitation in univariate analysis, but not in multivariate analysis. De Almeida et al. revealed that positive pressure ventilation in late preterm infants (34 to 36 weeks’ gestation) was associated with twin gestation, maternal hypertension, non-vertex presentation, Cesarean section, and lower gestational age [9]. Reis et al. proposed the use of a fuzzy expert system based on 61 risk situations to predict the need for positive pressure ventilation, endotracheal intubation, chest compression, and/or medications in the delivery room. Their sample was 10.2% preterm and 2.6% were < 34 weeks’ gestation [10].

Notwithstanding the previously established risk factors for neonatal resuscitation described herein, the goal of the present study was to establish early identification of risk factors in order to anticipate the need for personnel skilled in resuscitation. Thus, we included only those factors available in the KNN database that could be determined before birth. Each predictor variable has assigned a score, and the sums of the scores correspond to the infant’s risk of requiring extensive resuscitation. If the clinicians don’t have access to some of the variables, that pertinent score should be omitted. To date, there have been no data published to develop a clinical scoring system that can be individually used for the prediction of extensive delivery room resuscitation in VLBW infants.

Among the variables included in our prediction model, antenatal steroid use is the only modifiable risk factor. Several studies have shown that late preterm infants born to women who received antenatal steroid required less resuscitation at birth. A randomized trial showed that the betamethasone group required less resuscitation compared with the placebo group [11]. Even receiving a single dose of betamethasone led to less resuscitation [12]. A few studies have also shown that antenatal steroid is related to decreased extensive resuscitation [3]. In a population-based cohort study, infants who received chest compression and/or administration of epinephrine in the delivery room had received less antenatal steroid exposure compared with infants who did not receive extensive resuscitation, based on univariate analysis [13]. The current study supports the notion that antenatal steroid administration is significantly associated with decreased extensive resuscitation, based on univariate and multivariate regression analyses. Our final prediction model also included dose completion of antenatal steroid. The use of antenatal steroid improves lung function, with treated infants having higher Apgar scores and requiring less extensive resuscitation. Other factors may also contribute. The Brazilian Neonatal Research Network observed that antenatal corticosteroid-treated mothers had more prenatal medical visits compared with untreated mothers [14]. More prenatal care could result in improved pregnancy management, such as preventing preterm labor, thereby contributing to improved neonatal outcomes. In addition, there may have been urgent antenatal conditions (which are not provided in the KNN database) that disallowed enough time for steroid dose completion before delivery; such conditions may have independently affected neonates’ clinical status. In regression analysis, only no use of antenatal steroids had significant OR. However, prediction model could not be created when antenatal steroid was categorized as none and incomplete/complete. Additional multivariate regression analysis showed no or incomplete antenatal steroid has association with extensive resuscitation (OR and 95% CI: 1.54 [1.13–2.11]). Classifying antenatal steroid as none/incomplete and complete enabled us to develop a fair prediction model.

Abnormally decreased amniotic fluid volume may reflect fetal dysfunction that prevents normal urination, or it may represent a placental abnormality severe enough to impair perfusion [15]. Second-trimester rupture of the fetal membranes may also result in oligohydramnios [16, 17]. Few studies have investigated the correlation between oligohydramnios and resuscitation. Aziz et al. showed that oligohydramnios is a significant risk factor for positive pressure ventilation and/or endotracheal intubation [8]. Our analyses show that oligohydramnios is associated with extensive resuscitation in VLBW infants, and was one of the significant predictors of our model. Our data suggest that infants born to mothers with oligohydramnios who also have other unfavorable maternal and fetal conditions (e.g. fetal or placental insufficiency, premature rupture of membrane) have a worse prognosis at birth, and need more extensive resuscitation in the delivery room, compared with infants born to women with isolated oligohydramnios. This conclusion is consistent with the findings by Zhang et al. [18]

Common underlying causes of polyhydramnios include fetal congenital anomalies (approximately 15%) and diabetes (15–20%) [19]. Polyhydramnios is often a component of hydrops fetalis. Data regarding early neonatal complications from idiopathic polyhydramnios are conflicting. Some studies have found higher rate of newborn resuscitation with idiopathic polyhydramnios [20]. However, Panting-Kemp et al. showed that idiopathic polyhydramnios is unassociated with low 5-min Apgar score [21]. Our analyses support the notion that polyhydramnios is associated with extensive resuscitation in VLBW infants.

Our study aim was to develop a prediction model for extensive resuscitation using factors that can be clinically established before delivery. The variables we included were: gestational age, amniotic fluid, and antenatal steroid use. Our data suggest that the delivery by a woman with abnormal amniotic fluid volume, or in whom less antenatal steroid has been administered—despite gestational age > 27 weeks—should be prepared for extensive delivery room resuscitation. It should be attended by a team composed of at least three well-trained personnel with full resuscitation skills, and that equipment and supplies needed for extensive resuscitation should be prepared.

The present study was limited by only including risk factors available in the KNN database that could be determined before birth. Important variables that would allow assessment of the fetus, such as fetal heart rate, biophysical profile, fetal presentation, placenta abruptio, emergency Cesarean section, were not included in the KNN database. Male sex and extremely low birth weight infant were associated with extensive resuscitation at birth but were not used in the predictive model, because those factors cannot be clearly determined before labor. Another weakness of our predictive model is the low PPV. It results from the very low rate of extensive resuscitation. If a resuscitation team prepare for extensive resuscitation by using our model at a score cut-off of 2, only 8 out of 100 would be used. It could be safe for VLBW infants but not efficient, especially in hospitals with limited medical resources. Additional data and a larger sample, might improve the model for predicting extensive resuscitation in the delivery room.

The present study outlines factors that significantly increase the need for extensive resuscitation. These findings may be beneficial for developing strategies to anticipate circumstances that require more medical personnel and individuals with advanced neonatal resuscitation skills. Identifying risk factors and anticipating adequate levels of resuscitation that may be needed in the delivery room of a VLBW infant may better facilitate adequate preparation and prompt neonatal resuscitation, as well as target limited medical resources for those at the highest risk.

This study is the first to propose a clinical scoring system to predict extensive delivery room resuscitation in VLBW infants. Lower gestational age, abnormal amniotic fluid volume, and less use of antenatal steroid in VLBW infants are important predictors of extensive resuscitation in the delivery room. However, further studies are required to improve the performance of the prediction model and increase sensitivity of extensive resuscitation in VLBW infants.