Early Bubble CPAP and Outcomes in ELBW Preterm Infants
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Original ..............Article Early Bubble CPAP and Outcomes in ELBW Preterm Infants Vivek Narendran, MD, MRCP (UK) study first identified the Columbia approach of using ‘‘bubble Edward F. Donovan, MD continuous positive airway pressure (CPAP)’’ in the delivery room 1 Steven B. Hoath, MD as a possible strategy to reduce the incidence of BPD. A recent Henry T. Akinbi, MD comparison of outcomes between an NICU in Boston and the Columbia NICU, reinforced the apparent benefits of the Columbia Jean J. Steichen, MD 2 Alan H. Jobe, MD, PhD approach. Chronic lung disease, which occurs primarily in infants less than 1000 g (the ‘‘new BPD’’), is thought to have a qualitatively different pathogenesis than the traditional BPD described by 3 OBJECTIVE: Northway et al. Traditional BPD has a pathogenesis dominated by To test whether the introduction of early bubble continuous positive airway hyperoxic baro/volutrauma in surfactant deficient lungs, while the pressure (CPAP) results in improved respiratory outcomes in extremely low new BPD has a pathogenesis dominated by immaturity and birth-weight infants. alveolar hypoplasia. Recent evidence attributes these changes to prenatal (chorioamnionitis) and postnatal proinflammatory STUDY DESIGN: mediators (ventilator-induced lung injury), which are known to Outcomes of all infants between 401 and 1000 g born in a level 3 influence both lung development and lung injury.4 neonatal intensive care units (NICU) between July 2000 and October 2001 Several recent epidemiologic studies have demonstrated a (period 2) were compared using historical controls (period 1). Early decreased incidence of BPD by avoiding intubation in the delivery bubble (CPAP) was prospectively introduced in the NICU during period 1. room and using early (CPAP).5,6 There is little experimental Univariate and adjusted comparisons were made across time periods. information as to the mechanism whereby CPAP might minimize RESULTS: lung injury in a preterm lung. There is one study demonstrating Delivery room intubations, days on mechanical ventilation and use of decreased indicators of acute lung injury using bubble CPAP in a 7 postnatal steroids decreased ( p<0.001) in period 2, while mean days on preterm lamb model. Furthermore, there is a paucity of data CPAP, number of babies on CPAP at 24 hours (p<0.001) and mean regarding differences in gas exchange effectiveness between weight at 36 weeks corrected gestation also increased (p<0.05) after conventional and bubble CPAP systems. Bubble CPAP is a form of introduction of early bubble CPAP. oscillatory pressure delivery in which mechanical vibrations are transmitted into the chest secondary to the nonuniform flow of gas CONCLUSIONS: bubbles across a downstream water seal. This system results in Early bubble CPAP reduced delivery room intubations, days on waveforms similar to those produced by high-frequency ventilation mechanical ventilation, postnatal steroid use and was associated with when recorded by a transducer attached to the infant’s airway.8 increased postnatal weight gain with no increased complications. At present, there are no definitive studies and no clinical Journal of Perinatology (2003) 23, 195–199. doi:10.1038/sj.jp.7210904 consensus about the best approach to minimize ventilator- associated lung injury in extremely low birth-weight (ELBW) infants. Strategies vary from early delivery room surfactant administration and intermittent mandatory ventilation to early INTRODUCTION delivery room CPAP with or without pretreatment with surfactant.9 In 1987, Avery et al.1 reported large site differences in the risk- The primary objective of this study was to test whether the adjusted incidence of bronchopulmonary dysplasia (BPD) in a introduction of early bubble CPAP in the delivery room was safe group of 12 academic neonatal intensive care units (NICUs). This and resulted in improved respiratory outcomes in ELBW. We defined safety as improved respiratory outcomes without an increase in mortality and nonpulmonary morbidities such as Division of Neonatology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA. IVH and NEC. These outcomes along with growth parameters were monitored on a regular basis. Risk-adjusted comparisons Address correspondence and reprint requests to Vivek Narendran, MD, MRCP (UK), Division of Neonatolgy, 231 Bethesda Avenue, Medical Sciences Building, ML 6158, Cincinnati, of care and outcomes of infants during the two time periods OH 45267-0541, USA. were made. Journal of Perinatology 2003; 23:195–199 r 2003 Nature Publishing Group All rights reserved. 0743-8346/03 $25 www.nature.com/jp 195 Narendran et al. Bubble CPAP in the Delivery Boom METHODS In period 2, the neonatologists prospectively introduced routine, The study population comprised all infants with birth weights early, bubble nasal CPAP in the delivery room modeling closely the between 401 and 1000 g, born at a neonatal tertiary care unit Columbia method. Hudson nasal prongs were used to initiate in Cincinnati, OH, between 1 July 2000 and 10th October 2001 bubble CPAP immediately after the initial steps of drying and (period 2). These infants were compared to historical controls stimulation in all spontaneously breathing infants (Figure 1). The (period 1) born between 1 January 1998 and 31st December 1999. bubble CPAP circuit was very similar to conventional CPAP except The same group of neonatologists provided care in both periods. that the expiratory seal is an ‘underwater seal’ in the former The neonatal unit was part of the NICHD Neonatal Research compared to a mechanical device in the latter (Figure 2). The Network, and had extensive data collected prospectively throughout depth of immersion (5 cm) of the expiratory limb in 25% acetic the two time periods. acid determined the level of CPAP provided (5 cm of water). This was maintained constant during the study. The NICHD Neonatal Research Network is a consortium of s tertiary neonatal centers.10 The network maintains a registry of all Infants were electively intubated and given Survanta (Ross very low birth-weight (VLBW) infants (401–1500 g) born and/or Abbott Laboratories, OH), when FiO2 was greater than 60% to admitted to participating centers within 14 days of birth. This maintain saturations between 92 and 96%, pH <7.15, or PCO2 registry was developed to describe the populations at each >65. FiO2 was commonly adjusted using pulse oximetry to participating center, to survey neonatal practice, to assess morbidity maintain saturations between 92 and 96% and indwelling arterial and mortality rates, and to provide information for the planning of catheters were used sparingly. Ventilated infants were weaned randomized clinical trials. Trained research nurses collect aggressively and extubated back to CPAP as early as possible. maternal demographic, pregnancy and delivery data soon after Infants were monitored for neonatal morbidities for a period of 120 birth and infant data until 120 days, discharge, or death. days unless discharged or transferred to another hospital. In period 1, infants were managed with intermittent positive Statistical Analysis pressure ventilation with bag and mask in the delivery room, early Data were retrospectively analyzed by w2-test and continuous t-test intubation, surfactant administration and intermittent mandatory for comparisons between the two time periods and expressed as ventilation for infants with moderate-to-severe respiratory distress proportions. Results were considered to be statistically significant syndrome. CPAP was not used in the delivery room and CPAP was for p<0.05. rarely introduced in the early management of RDS compared to intubation and surfactant administration. FiO2 was adjusted based on transcutaneous PaO2 or arterial PaO2 from an indwelling arterial catheter. No new major technologies or clinical practice RESULTS guidelines were introduced in the intensive care units during the Demographic characteristics did not differ during the two study two study periods. periods (Table 1). When compared to period 1, after initiation of Figure 1. Premature infant in incubator on bubble CPAP. 196 Journal of Perinatology 2003; 23:195–199 Bubble CPAP in the Delivery Boom Narendran et al. Figure 2. Schematic diagram of bubble CPAP circuit. early bubble CPAP, delivery room intubations, days on mechanical Table 1 Demographics and Non Pulmonary outcomes ventilation and postnatal steroid use decreased (Table 2). Infants Before CPAP After CPAP on CPAP at 24 hours and number of days on CPAP also increased (Table 2). Mean weight at 36 weeks corrected gestational Number of admissions 92 79 age increased (Table 1). Chronic lung disease defined as Mean gestational age (weeks) 26 26 oxygen requirement at 36 weeks corrected gestational age Mean birth weight (g) 763 753 tended to decrease but was not statistically significant. Mean Female (%) 46 54 White (%) 54 58 length and head circumference at 36 weeks corrected gestational Mortality (%) 38 34 age tended to increase. Other nonpulmonary morbidities Age at full enteral feeds (days) 24 18 tended to decrease except PDA (Table 1). There were three ICH (grades 3 & 4) (%) 9.8 6.3 infants with septal erosions, which resolved spontaneously and PDA (%) 33.7 44.3 required no surgical intervention. No infant in period NEC (%) 12 8.9 2 developed a pneumothorax. Mean weight at 36 weeks (g) 1917 2134** Mean length at 36 weeks (cm) 41.5 42.2 Mean head circumference at 36 weeks (cm) 31 31.6 DISCUSSION **P<0.05 univariate analysis for comparisons over two time periods.