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* Departments of Pediatrics
Biostatistics, George Washington University Medical Center and the Children’s National Medical Center, Washington, DC
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONREFERENCES |
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Methods. All ELBW infants who were born at our hospital since the institution of the ENCPAP practice (n = 101) were analyzed retrospectively. Patients were divided into 3 terciles according to their birth date. A baseline group of ELBW infants who were born in the 2 years preceding the institution of the ENCPAP practice (group 0; n = 45) were used for comparison. Trends in practices and outcomes over time were analyzed using the 2-sided Cochran-Armitage linear trend test. Statistical significance for these trends were then analyzed again using a multivariate regression model controlling for significant variables. Bivariate analyses comparing individual groups were also conducted.
Results. There were no significant trends in mortality rate among the baseline group and the 3 terciles since the institution of the ENCPAP practice (26.7% vs 26.5% vs 11.8% vs 18.2%). ENCPAP management increased in the surviving infants over time (14% vs 19.2% vs 65.52% vs 70.4%), whereas the use of surfactant decreased (51.5% vs 48% vs 13.3% vs 33.3%) and the incidence of bronchopulmonary dysplasia (BPD) decreased (33.3% vs 46.2% vs 25.9% vs 11.1%). The average ventilator days per infant decreased, the rate of sepsis decreased, and the average daily weight gain increased. There were no significant trends in the incidence of intraventricular hemorrhage or necrotizing enterocolitis (NEC). When comparing the cohorts of survivors in the 3 terciles since the institution of ENCPAP system, ELBW infants who were started on ENCPAP but intubated within 1 week (CPAP failure) decreased over time (38.5% vs 13.8% vs 7.4%). There were other trends that did not reach significance, such as increased incidence of necrotizing enterocolitis (NEC). In a multivariate analysis controlling for gestational age, birth weight, and sepsis, the incidence of BPD was significantly lower over time (regression coefficient = –1.002 ± 0.375).
Conclusions. The frequency of use of ENCPAP in ELBW infants and its success improved in our unit over time. The major positive association in this population was a reduction in BPD rates and an increase in average weight gain. Relation of ENCPAP and NEC should be evaluated further.
Key Words: nasal CPAP • extremely low birth weight infants • bronchopulmonary dysplasia
Abbreviations: ENCPAP, early nasal continuous positive airway pressure • DR, delivery room • ELBW, extremely low birth weight • BPD, bronchopulmonary dysplasia • IVH, intraventricular hemorrhage • ROP, retinopathy of prematurity • NEC, necrotizing enterocolitis • NICU, neonatal intensive care unit
Early nasal continuous positive airway pressure (ENCPAP) has been suggested as a management strategy in preterm infants with respiratory distress.1–5 The definitive evaluation of risks and benefits of ENCPAP will be established only with a randomized clinical trial, yet some centers, encouraged by existing reports on this form of respiratory management,5–8 are attempting to implement ENCPAP as an alternative to routine delivery room (DR) intubation. Centers are relying on the limited body of literature suggesting improved clinical outcomes in association with ENCPAP. In the absence of results of a randomized trial, it is important to expand the body of knowledge on this topic by sharing experiences of centers that are engaged in this management strategy. Such reports may build a stronger consensus regarding the benefits and limitations of this technology.
An important aspect that needs to be addressed while planning for a randomized clinical trial is the recognition of the need for a transitional learning period during the initial phases of implementing an ENCPAP system in a unit. Significant training and familiarization must occur at the physician, nursing, and respiratory therapist levels to ensure accurate and effective application and maintenance of ENCPAP. The need for training is 2-fold. First, training that is focused on the technical aspects of implementing the ENCPAP system is required to establish a higher level of vigilance in selecting the appropriate size prongs and suction catheters for the infants’ nasal passage, maintaining patency of the nasal airway without causing nasal septum trauma, identifying early signs of respiratory compromise while on the ENCPAP system, and finally troubleshooting for different causes of CPAP failure. The second focus of training aims at changing attitudes of caregivers regarding early respiratory care and overcoming barriers created by established methods of care, such as routine tracheal intubation in the DR without careful assessment of the infants’ respiratory efforts and/or response to facial CPAP before intubation and avoiding hasty intubation as a response to respiratory compromise while on ENCPAP without appropriate evaluation of the patient and the CPAP circuit. Such a process takes time, and as a consequence, the clinical outcomes are expected to evolve along the experiential curve of the implementation team in the unit.
In this report, we share our experience with the introduction and then implementation of ENCPAP with extremely low birth weight (ELBW) infants in the past 4 years. We examined the rates of ENCPAP failure and the need to intubate in the DR during that implementation period. We also evaluated the effect of passage of time, associated with improved clinical experience, on pulmonary and nonpulmonary outcomes in infants who were hospitalized in our unit. Pulmonary outcomes included the incidence of bronchopulmonary dysplasia (BPD) and air leak syndromes, as well as the duration of mechanical ventilation. Nonpulmonary outcomes include the incidence of intraventricular hemorrhage (IVH), retinopathy of prematurity (ROP), necrotizing enterocolitis (NEC), and sepsis (defined as clinical signs and symptoms associated with a positive blood culture). Survival rate, average daily weight gain, and hospital length of stay were also analyzed.
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METHODS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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NCPAP Training
A clear policy for the use of ENCPAP as the initial airway management was laid out. The written policy included a description of the mechanical components of the system, indications for initiation of therapy, maintenance and care of airway, the weaning procedure, and troubleshooting. Indicators for failure of ENCPAP were defined, with recommendation for immediate tracheal intubation and initiation of mechanical ventilation in the event of failure. A videotape that visually demonstrated the procedures was produced and provided to all nurses and physicians. Lectures on the subject were also integrated into the new nurses’ orientation curriculum. Attending physicians met routinely to discuss cases and learn from each other’s experiences, and fellows and residents were trained as they rotated through the unit. The implementation of the new ENCPAP system started within 1 month from the end of the formal training period (September 1997).
Respiratory Management
The following procedures were introduced with the ENCPAP management protocol. Infants are initially dried, stimulated, and assessed in the DR. ELBW infants with spontaneous respiratory efforts are offered distending pressure (5 cm H2O) via Carden valve while being prepared for and during transport to the NICU. ELBW infants are then immediately transported to the NICU. A water-seal CPAP unit is always ready in the NICU (Fig 1). 5 Infants are immediately placed on NCPAP of 5 cm H2O using the nasal prongs of Hudson Respiratory Care (Temecula, CA). Should an infant show signs of respiratory compromise, such as severe retraction, frequent apnea, or increased oxygen requirement (fraction of inspired oxygen >60%), then he or she will be intubated immediately and started on conventional mechanical ventilation. In the DR, ELBW infants who do not breathe spontaneously are supported with bag-and-mask ventilation for 30 seconds. If they continue not to breathe spontaneously, then they are intubated immediately and supported with conventional mechanical ventilators. Intratracheal surfactant therapy is offered only on an individualized rescue basis depending on the clinical and radiographic presentation. Thus, ELBW infants are not routinely exposed to tracheal intubation just for the purpose of surfactant administration. Birth weight and gestational age are not criteria for consideration or exclusion of the ENCPAP in the DR (Fig 2).
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2 approximation), analysis of variance, and 2-sided t test as appropriate. |
RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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The need to intubate initially and then switch to NCPAP within the first 24 hours of life decreased significantly in the 3 terciles since the institution of the ENCPAP system (32.4% vs 17.6% vs 9.1%; P = .017). When the baseline comparison group was added to the analysis, significance was lost (Table 2). Similarly, the rate of ENCPAP failure and switch to conventional ventilation within the first week of life decreased significantly over the 3 terciles (29.4% to 11.8% to 9.1%; P < .01), but, again, significance was lost when the baseline comparison group was added (Table 2). Variability in surfactant treatment showed a significant trend to decline among the 4 groups over time (51.5% vs 48.0% vs 13.3% vs 33.3%; P = .02; Table 2). There was a significant decrease in the use of surfactant from the first tertile to the second (P = .007).
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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70% for the 2 consecutive terciles. Over the same time span, rates for BPD for this population decreased from 46.15% to 11.11%. Overall surfactant usage and ventilator days decreased as well, and patients’ daily weight gain improved over time. Other nonpulmonary outcomes showed no significant change, suggesting that ENCPAP is associated with a significant reduction in the rate of BPD without significant nonpulmonary complications. The results of this report serve 2 benefits. The first is to demonstrate that a reduction in the rate of tracheal intubation, along with increasing rate of the use of ENCPAP, is associated with a decreased rate of BPD over time. The second benefit is the demonstrated need of a time-dependent learning curve for the institution of a de novo policy of ENCPAP in the NICU.
There are several difficulties in establishing and maintaining the use of ENCPAP as reported by a number of centers.6,9 First is the negative influence of ENCPAP on the feasibility of surfactant administration. Our results do not show any potential negative consequences for such an association. It can be argued that these results do not support a measurable benefit for the use of prophylactic surfactant in this weight category. The rate of surfactant administration as a rescue measure after establishing the ENCPAP management strategy in our experience did not reach 35% of the cases. This could be considered a significant cost saving with no associated risk. Second, the approach to use ENCPAP in the DR requires an adequate level of professional experience to conduct the initial clinical evaluation of the infants’ respiratory status and a level of confidence to proceed with the decision of implementing ENCPAP in the DR. Third, once the infant is admitted to the NICU, he or she requires meticulous attention and gentle care to the nasal airway, which translates into increased nursing care. One of the significant changes required in the evolution of our experience was to assign the most experienced nurses to deliver care to the ELBW infants on ENCPAP during the first week of life. The health care delivery team needs to adopt a "minimal handling" awareness to avoid infant stress during the first few days on ENCPAP.
Our study has several limitations. First, the comparison groups are not contemporaneous; therefore, the likelihood exists that changes in other aspects of management in our NICU over the 4-year period could have contributed to the variation in outcomes over time. Second, we attempted in our multivariate model to control for a number of demographic and early indicators of illness, such as gestational age, birth weight, race, and gender, but we were limited by the breadth of the original data set that we used to extract this information. Some important data, such as prenatal steroid use, are missing from our data set. However, existing reports did not yet confirm a clear association between antenatal steroid use and reduction in BPD in the ELBW infants.10,11 It would have been useful to use a standardized acuity of illness scores such as Score of Neonatal Acute Physiology or Clinical Risk Index for Babies scores.12 Nevertheless, birth weight alone has shown an excellent correlation with these standardized scoring systems in predicting severity of illness and mortality in very low birth weight infants.13 Third, the statistical analysis of our results did not show significance in various trends that seemed to follow an encouraging pattern, such as incidence of IVH grades III to IV (P = .22), ROP stages III to IV (P = .3), and average duration of hospital stay (P = .33), and others that were concerning, such as NEC (P = .72). This is a consequence of the small sample size (n = 146). Because the population size of the ELBW infants is expected to be small in most NICUs, perhaps a multisite analysis would be helpful. The downside of such a design would be discrete differences in practice among units that would be difficult to quantify and control for in a nonrandomized design.
Our results, despite the limitations mentioned earlier, show a strong parallel trend between success in implementing ENCPAP as a modality of respiratory management and improved outcomes such as a reduction of incidence of BPD. This is a significant finding because centers that decide to participate in a randomized trial must first ascertain the level of comfort that their personnel have with the technology before evaluating its efficacy. It is plausible that improved outcomes could also be linked to another concurrent trend of an intermediate variable, such as reduced rates of nosocomial sepsis. However, the reduction of tracheal intubation and the decreased number of ventilator days by themselves can decrease the incidence of ventilator-related nosocomial sepsis. It is not clear whether reduced infection is a contributing cause or rather a consequence of such a new management strategy. Of note, the decreased incidence of BPD among the 3 terciles in this study remained significant after controlling for sepsis, using a multiple logistic analysis (regression coefficient = –1.002 ± 0.375; P = .008). The increase in average weight gain may be a consequence of decreased rates of BPD. A reduction in work of breathing and energy expenditure is expected in ELBW infants who are spared the clinical manifestation of chronic lung disease.
We are troubled with the unfavorable trend toward increased incidence of NEC over time since the institution of ENCPAP. This trend does not reach significance but still deserves careful monitoring. Abdominal distention in association with NCPAP has been previously noted and defined as "benign" gaseous distention13; this nomenclature needs to be verified. We encountered a challenge when feeding these ELBW infants to determine when this benign distention would evolve into more serious consequences.
The failure rate of ENCPAP decreased significantly over time in the 3 terciles but lost significance when the baseline group of infants was included in the analysis. This latter phenomenon may be a confounder attributable to the very small fraction (11%) of ELBW infants who were maintained on NCPAP in the first week of life in group 0 and whose clinical course may not be generalizable to the entire NICU cohort within the same weight category. Similarly, the trend for extubation to NCPAP significantly decreased in the 3 terciles because the number of infants who were intubated and ventilated at birth decreased significantly over time in these 3 terciles. This trend of a decreasing rate of extubation was lost when the baseline group was added to the comparison. This could be attributed to the fact that during the first tertile of our ENCPAP experience, many infants who initially were intubated were then extubated within 24 hours because they were found to be eligible for ENCPAP management. This trend changed over time because better judgments were made in the DR to initiate ENCPAP and therefore the need for early extubation diminished.
Finally and most important, the issue of safety when adopting such an ENCPAP strategy should be explored. We are encouraged with the favorable trend toward a decreased incidence of IVH in association with the use of ENCPAP (P = .22). This is in agreement with a previous anecdotal report relating NCPAP with a decreased incidence of IVH in ELBW infants.7 From this report and ours, we may assume that ENCPAP is associated with a decreased incidence of IVH or at least does not seem to increase that risk. A long-term neurodevelopmental follow-up will help to address the concern for more subtle forms of neuronal injury.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Reprint requests to (H.A.) 900 23rd St, NW, Suite G2092, Room G132, Washington, DC 20037. E-mail: haly{at}cnmc.org
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REFERENCES |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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