SciELO - Scientific Electronic Library Online

 
vol.24 issue2Influence of early mobilization on respiratory and peripheral muscle strength in critically ill patientsThe correlation between plasma lactate concentrations and early neonatal mortality author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Article

Indicators

Related links

  • Have no similar articlesSimilars in SciELO

Share


Revista Brasileira de Terapia Intensiva

Print version ISSN 0103-507X

Rev. bras. ter. intensiva vol.24 no.2 São Paulo Apr./June 2012

http://dx.doi.org/10.1590/S0103-507X2012000200014 

ORIGINAL ARTICLES - CLINICAL RESEARCH

 

Prevalence and factors associated with bronchopulmonary dysplasia in a referral hospital in Minas Gerais, Brazil

 

 

Brunnella Alcantara Chagas de FreitasI,II; Mirene PelosoI; Guilherme Lobo da SilveiraIII; Giana Zarbato LongoIV

IDepartment of Medicine and Nursing, Universidade Federal de Viçosa - UFV - Viçosa (MG), Brazil
II
Graduate Program in Nutritional Science, Department of Nutrition and Health, Universidade Federal de Viçosa - UFV - Viçosa (MG), Brazil
III
Neonatal Intensive Care Unit, Hospital São Sebastião - Viçosa (MG), Brazil
IV
Department of Nutrition and Health, Universidade Federal de Viçosa - UFV - Viçosa (MG), Brazil

Corresponding author

 

 


ABSTRACT

OBJECTIVE:The aim of the present study was to evaluate the prevalence and factors associated with bronchopulmonary dysplasia at a neonatal intensive care unit.
METHODS: The study was a cross-sectional study that used secondary data from premature infants who were born with less than 32 weeks of gestational age and were admitted to a neonatal intensive care unit. Chi-square, Mann-Whitney and multivariate tests were used. Significance was set at p<0.05.
RESULTS: A total of 88 premature infants were included in the study. Bronchopulmonary dysplasia occurred in 27.3% of the infants and was related to having a gestational age below 28 weeks (OR: 4.80; 95% CI: 1.50-15.34; p=0.008) and a patent ductus arteriosus (OR: 3.44; 95% CI: 1.10-10.76; p=0.034). The group with bronchopulmonary dysplasia used mechanical ventilation for a longer duration, with a median of 24.5 days (p<0.0001). At discharge, the corrected and chronological ages were higher in the group with bronchopulmonary dysplasia (p<0.0001), with respective medians of 38.4 weeks and 70.5 days.
CONCLUSIONS: In tthis study, the prevalence of bronchopulmonary dysplasia was high; the high prevalence was related to extreme prematurity, patent ductus arteriosus, a longer period under mechanical ventilation and prolonged hospitalization. The increased survival of infants with low gestational age makes this disorder a public health issue.

Keywords: Bronchopulmonary dysplasia; Infant, premature; Infant, low birth weight; Infant, premature, diseases


 

 

INTRODUCTION

Perinatal medicine and improvements in neonatal intensive care have led to increased survival of premature infants with very low birth weights. This benefit is countered by the higher incidence of bronchopulmonary dysplasia (BPD), which has become a feared complication in premature infants.(1)

BPD is a chronic pulmonary disease that affects premature infants and contributes to their morbidity and mortality. Despite substantial changes in incidence, risk factors and severity after the introduction of new therapies and mechanical ventilation (MV) techniques, BPD remains common. Its pathogenesis is multifactorial and includes immaturity, oxygen toxicity, infection, patent ductus arteriosus (PDA) and poor postnatal nutrition.(2-8)

According to the population under study, the neonatal care and the diagnostic criteria used, the prevalence of BPD varies from 20 to 40%.(9-11) Knowledge of factors that are associated with BPD development contributes to its prevention; BPD often results in prolonged hospitalization, which has consequences for the premature infants, their families and society.(12)

The present study assessed the prevalence and factors associated with BPD in premature infants in the Neonatal Intensive Care Unit (NICU) at Hospital São Sebastião in Viçosa (MG), Brazil.

 

METHODS

Study characteristics

The study was a cross-sectional study that used secondary data from premature infants who were admitted to the NICU at Hospital São Sebastião in the period of January 1, 2008 to December 31, 2010.

The study included premature infants who were born with less than 32 weeks of gestation. Because of the loss of monitoring data, infants who died or were transferred to another hospital before 36 weeks of corrected age were excluded from the study.

The study was approved by the Human Research Ethics Committee at the Universidade Federal de Viçosa (number 063/2011) and informed consent was waived.

Variables analyzed

The variable "outcome, BPD" was categorized as "yes" or "no" and was defined as oxygen-therapy dependence at 36 weeks of corrected age, even in cases that were associated with pneumonia, meconium aspiration, gastrointestinal abnormalities and heart disease.(13,14)

The following explanatory variables were analyzed:

- Maternal characteristics (qualitative): maternal age (less than 20 years, 20 to 34 years and more than 34 years); prenatal care (yes, no); use of antenatal corticosteroid (at least one dose - yes, no); multiple births (yes, no); maternal hypertensive syndrome and termination of labor (cesarean);

- Premature infant characteristics (qualitative): newborn origin (born at another hospital – yes, no); gender; Apgar < 7 at the 5th minute; Clinical Risk Index for Babies (CRIB) ≥ 10;(15) gestational age below 28 weeks; small for gestational age (SGA - weight below the 10th percentile of Lubchenco curves); infant respiratory distress syndrome (IRDS); PDA; late sepsis and the use of two or more doses of surfactant (based on clinical, radiological and/or blood gas parameters). The CRIB score was adopted as a measure of the severity at admission, which is indicated for premature infants with an age below 32 weeks; the CRIB is a simple method that is easy to apply because it is based on record data that are routinely monitored in the first 12 hours after birth;(16)

- Premature infant characteristics (quantitative): time under MV (according to the actual routine, based on clinical, radiological and/or blood gas criteria); total period of oxygen therapy; weight at birth; gestational age at birth (defined by the best estimate between the ultrasonography before 20 weeks, the last menstrual period and the clinical examination); age at onset of enteral feeding; age at onset of parenteral nutrition (PN); age at onset of full diet (150 mL/kg/day);(17-20) age when birth weight was recovered; weight at discharge and corrected and chronological age at discharge.

Statistical analysis

The sample size was calculated using the Stat Calc from Epi Info (version 7.0) with a sample power of 80% plus a 95% confidence interval (95% CI): 84 patients were required.

The relative frequencies, medians and maximum and minimum values were obtained. For the qualitative analysis, a Pearson's chi-squared test or a Fisher's exact test was used, and for quantitative analysis, a Mann-Whitney test was used. A p<0.05 was considered significant. A backward LR stepwise multiple regression was applied to explanatory variables that displayed p<0.20, which related them to the variable "outcome, BPD (yes or no)''. The software Statistical Package for the Social Sciences (SPSS, version 17.0) was used for the analyses.

 

RESULTS

In the period of study, 502 patients were admitted to the NICU (47.4% of the total population since the unit was opened). Of those, 336 were premature infants (66.9%), and records were found for 293 of the infants. A total of 43.3% (n=127) of the infants were younger than 32 gestational weeks, from whom 24,4% (n=31) died before reaching 36 corrected weeks of age. From those 96 premature infants, eight were excluded from the study because of a loss of monitoring data (they were transferred to another hospital before 36 weeks of corrected age). Thus, after applying the inclusion and exclusion criteria, the final sample had 88 patients.

BPD occurred in 27.3% of the population studied (n=24). Maternal and premature infant characteristics and their association with BPD development were evaluated.

The maternal variables "age", "antenatal corticosteroid use", "at least one prenatal appointment", "twinning", "hypertensive syndrome" and "cesarean delivery" did not differ between the groups with and without BPD (Table 1).

 

 

Regarding the premature infant characteristics, the group with BPD was related to a gestational age below 28 weeks (p<0.0001), the occurrence of IRDS (p=0.027), PDA (p=0.001) and late sepsis (p=0.025) (Table 2).

 

 

The medians for gestational age were lower in the BPD group than in the group without BPD (28.0 and 30.1 weeks, respectively; p=0.001). Similar outcomes were observed with the birth weight medians, which were 1,049 g and 1,356 g, respectively (p=0.002). A delay in the onset of full diet ingestion was evident in the premature infants with BPD (median of 24.5 days; p=0.042).

Backward LR stepwise multiple regression was applied to variables showing p<0.20, which included gestational age below 28 weeks, birth weight, IRDS, PDA, late sepsis, age at onset of full diet, age of recovered weight and a CRIB score ≥ 10. However, confounding factors for a CRIB score ≥ 10, age at onset of full diet and recovered weight led to their removal from the analysis.

The variables related to BPD occurrence that remained in the final model were gestational age below 28 weeks (OR: 4.80; 95% CI: 1.50-15.34; p=0.008) and PDA (OR: 3.44; 95% CI: 1.10-10.76; p=0.034).

There were significant differences for the period under MV and total oxygen therapy (p<0.0001), and there were higher medians for the period under MV and total oxygen therapy in the BPD group, with values of 24.5 days and 61.0 days, respectively (Table 3).

 

 

At the moment of NICU discharge, the variables "weight", "corrected age" and "chronological age" were higher in the BPD group (p<0.0001), with medians of 2,667 g, 38.4 weeks and 70.5 days, respectively. The higher corrected and chronological age at discharge justified the higher weights of premature infants with the disease, as gestational age and birth weight were also lower.

 

DISCUSSION

In the present study, the BPD prevalence of 27.3% was higher than the prevalence in other studies; previous results have varied from 15.3% to 24%.(14,21,22) However, if the analysis included eight patients transferred back to their hometowns without oxygen support (therefore likely having no BDP; these patients were excluded from the sample as were not followed until 36 weeks of corrected gestational age), the prevalence would be lower, at levels comparable to the mentioned studies. Thus, BPD as a complication of prematurity remains a common disease and a major public health problem because there have been increased rates of infant survival at lower gestational ages.(23)

For the maternal variables analyzed, there were no differences between the groups; however, the use of antenatal corticosteroid is known to be protect against BPD.(11) Gestational hypertension also provides some protection, which is likely related to the birth of more mature premature infants.(24,25) Furthermore, a cesarean delivery may be related to induced prematurity when it is necessary to interrupt the pregnancy.(11)

The present study found a higher occurrence of BPD when prematurity was extreme. Although gestational age is an important predictor of BPD,(21,26-28) there are other factors that contribute to BPD, as shown by the association between BPD and IRDS.(11)

The association between PDA and BPD shown in the present study has been corroborated by other authors,(21,29) although it was not observed by Tauzin et al.(30) Even with the clinical and surgical treatment of PDA, Laughon et al.(31) and Kugelman and Durand(29) did not observe a reduction in the occurrence of BPD. Therefore, conservative clinical measures that aim at PDA prevention should be established, such as fluid restriction and adequate ventilation support.(29,32)

This study found an association between longer MV duration and the occurrence of BPD, which has also been found by other authors.(5,12,27,33,34) A reduction in disease incidence has been reported with the decrease in MV duration.(5,33-38) The increased use of nasal continuous positive airway pressure (CPAP) is suggested as a protective ventilation strategy that is an alternative to invasive ventilation, and the practice of early extubation can lead to reduced MV duration. Authors promote the use of CPAP as the primary therapy or after surfactant administration.(34-38) However, there has been limited success of CPAP maintenance without the need for posterior intubation, especially in extremely premature infants.(39)

The risk of BPD development can be substantially reduced by decreasing MV duration.(5,33) However, one must consider that prematurity, either alone or when it is associated with several perinatal complications, can determine the MV duration and the consequent risk of BPD.(4,27,40,41)

This study has not confirmed the association between BPD and the feeding practices and nutritional aspects that were evaluated. However, the authors confirmed that once the disease had developed, the premature infants required longer durations of ventilation support and hospital stays, which also suggests greater nutritional inadequacy.(11,28) In this regard, early nutritional support is important as a preventive measure for BPD,(29) and there should be an emphasis on the adequate supply of enteral feeding, even with supplementation by parenteral nutrition.(6,42)

The present study highlights the longer duration of hospital stays in the group who developed BPD. The inherent risks of prolonged hospitalization result in social and financial costs that have been corroborated by other authors.(11,28,43)

 

CONCLUSIONS

The present study has several limitations related to cross-sectional and single-center studies, although it contextualizes a period of three years in the assessed unit, which has been in operation for six years. Because of its characteristics, the present study is not a cause and effect study but one of association.

Reducing the incidence of prematurity is the most effective way to alleviate BPD. If premature birth has occurred, we highlight the necessary dissemination of practices that prevent PDA development and the use CPAP as an alternative to invasive ventilation; additionally, early extubation should aim to decrease the duration of MV. Further studies are suggested to encourage the use of CPAP.

 

REFERENCES

1. Avery ME, Tooley WH, Keller JB, Hurd SS, Bryan MH, Cotton RB, et al. Is chronic lung disease in low birth weight infants preventable? A survey of eight centers. Pediatrics. 1987;79(1):26-30.         [ Links ]

2. Monte LF, Silva Filho LV, Miyoshi MH, Rozov T. Displasia broncopulmonar. J Pediatr (Rio J). 2005;81(2):99-110.         [ Links ]

3. Oh W, Poindexter BB, Perritt R, Lemons JA, Bauer CR, Ehrenkranz RA, Stoll BJ, Poole K, Wright LL; Neonatal Research Network. Association between fluid intake and weight loss during the first ten days of life and risk of bronchopulmonary dysplasia in extremely low birth weight infants. J Pediatr. 2005;147(6):786-90.         [ Links ]

4. Kinsella JP, Greenough A, Abman SH. Bronchopulmonary dysplasia. Lancet. 2006;367(9520):1421-31.         [ Links ]

5. Kwinta P, Grudzień A, Pawlik D, Olechowski W, Lauterbach R, Pietrzyk JJ. [Prevalence and risk factors of bronchopulmonary dysplasia among extremely low birth weight newborns of regional birth cohort of south-east Poland]. Przegl Lek. 2009;66(1-2):14-20. Polish.         [ Links ]

6. Wemhöner A, Ortner D, Tschirch E, Strasak A, Rüdiger M. Nutrition of preterm infants in relation to bronchopulmonary dysplasia. BMC Pulm Med. 2011;11:7.         [ Links ]

7. Bhatia J, Parish A. Nutrition and the lung. Neonatology. 2009;95(4):362-7.         [ Links ]

8. Mello RR, Dutra MV, Lopes JM. Morbidade respiratória no primeiro ano de vida de prematuros egressos de uma unidade pública de tratamento intensivo neonatal. J Pediatr (Rio J). 2004;80(6):503-10.         [ Links ]

9. Manktelow BN, Draper ES, Annamalai S, Field D. Factors affecting the incidence of chronic lung disease of prematurity in 1987, 1992, and 1997. Arch Dis Child Fetal Neonatal Ed. 2001;85(1):F33-5.         [ Links ]

10. Verhagen AA, Keli SO, van der Meulen GN, Wiersma H, Arias M, Angelista IR, et al. Surfactant treatment in premature infants with Respiratory Distress Syndrome in Curaçao. West Indian Med J. 2001;50(2):117-22.         [ Links ]

11. Cunha GS, Mezzacappa Filho F, Ribeiro JD. Fatores maternos e neonatais na incidência de displasia broncopulmonar em recém-nascidos de muito baixo peso. J Pediatr (Rio J). 2003;79(6):550-6.         [ Links ]

12. Gonzaga AD, Figueira BB, Sousa JM, Carvalho WB. Tempo de ventilação mecânica e desenvolvimento de displasia broncopulmonar. Rev Assoc Med Bras (1992). 2007;53(1):64-7.         [ Links ]

13. Minas Gerais. Secretaria de Estado da Saúde. Assistência hospitalar ao neonato. Belo Horizonte; 2005.         [ Links ]

14. Fanaroff AA, Hack M, Walsh MC. The NICHD neonatal research network: changes in practice and outcomes during the first 15 years. Semin Perinatol. 2003;27(4):281-7.         [ Links ]

15. The CRIB (clinical risk index for babies) score: a tool for assessing initial neonatal risk and comparing performance of neonatal intensive care units. The International Neonatal Network. Lancet. 1993;342(8865):193-8. Erratum in: Lancet 1993;342(8871):626.         [ Links ]

16. Matsuoka OT, Sadeck LS, Haber JF, Proenca RS, Mataloun MM, Ramos JL, et al. Valor preditivo do "Clinical Risk Index for Babies" para o risco de mortalidade neonatal. Rev Saúde Pública. 1998;32(6):550-5.         [ Links ]

17. Sisk PM, Lovelady CA, Gruber KJ, Dillard RG, O'Shea TM. Human milk consumption and full enteral feeding among infants who weigh </=1250 grams. Pediatrics. 2008;121(6):e1528-33. Erratum in Pediatrics. 2008;122(5):1162-3.         [ Links ]

18. Kuzma-O'Reilly B, Duenas ML, Greecher C, Kimberlin L, Mujsce D, Miller D, et al. Evaluation, development, and implementation of potentially better practices in neonatal intensive care nutrition. Pediatrics. 2003;111(4 Pt 2):e461-70.         [ Links ]

19. Premji SS, Fenton TR, Sauve RS. Higher versus lower protein intake in formula-fed low birth weight infants. Cochrane Database Syst Rev. 2006(1):CD003959.         [ Links ]

20. Premji S, Chessell L. Continuous nasogastric milk feeding versus intermittent bolus milk feeding for premature infants less than 1500 grams. Cochrane Database Syst Rev. 2001(1):CD001819. Review. Update in: Cochrane Database Syst Rev. 2003;(1):CD001819.         [ Links ]

21. Rocha G, Ribeiro O, Guimaraes H. Fluid and electrolyte balance during the first week of life and risk of bronchopulmonary dysplasia in the preterm neonate. Clinics (Sao Paulo). 2010;65(7):663-74.         [ Links ]

22. Rede Brasileira de Pesquisas Neonatais. Relatório anual 2009 [cited 2011 Sep]; Available from: http://www.redeneonatal.fiocruz.br/images/stories/relatorios/rbpn2009.pdf        [ Links ]

23. Stoll BJ, Hansen NI, Bell EF, Shankaran S, Laptook AR, Walsh MC, Hale EC, Newman NS, Schibler K, Carlo WA, Kennedy KA, Poindexter BB, Finer NN, Ehrenkranz RA, Duara S, Sánchez PJ, O'Shea TM, Goldberg RN, Van Meurs KP, Faix RG, Phelps DL, Frantz ID 3rd, Watterberg KL, Saha S, Das A, Higgins RD; Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. Neonatal outcomes of extremely preterm infants from the NICHD Neonatal Research Network. Pediatrics. 2010;126(3):443-56.         [ Links ]

24. Cunha I, Brissos S, Dinis M, Mendes I, Nobre A, Passão V. Comparison between the results of the Symptom Checklist-90 in two different populations with temporal lobe epilepsy. Epilepsy Behav. 2003;4(6):733-9.         [ Links ]

25. Kim CR, Vohr BR, Oh W. Effects of maternal hypertension in very-low-birth-weight infants. Arch Pediatr Adolesc Med. 1996;150(7):686-91.         [ Links ]

26. Zeitlin PL, Nogee LM. Etiology of bronchopulmonary dysplasia: before birth. Pediatr Allergy Immunol Pulmonol. 2011;24(1):21-5.         [ Links ]

27. Cooke RW. Factors associated with chronic lung disease in preterm infants. Arch Dis Child. 1991;66(7 Spec No):776-9.         [ Links ]

28. Egreteau L, Pauchard JY, Semama DS, Matis J, Liska A, Romeo B, et al. Chronic oxygen dependency in infants born at less than 32 weeks' gestation: incidence and risk factors. Pediatrics. 2001;108(2):E26.         [ Links ]

29. Kugelman A, Durand M. A comprehensive approach to the prevention of bronchopulmonary dysplasia. Pediatr Pulmonol. 2011;46(12):1153-65.         [ Links ]

30. Tauzin L, Joubert C, Noel AC, Bouissou A, Moulies ME. Effect of persistent patent ductus arteriosus on mortality and morbidity in very low-birthweight infants. Acta Paediatr. 2012;101(4):419-23.         [ Links ]

31. Laughon MM, Smith PB, Bose C. Prevention of bronchopulmonary dysplasia. Semin Fetal Neonatal Med. 2009;14(6):374-82.         [ Links ]

32. Sekar KC. Protective strategies to prevent patent ductus arteriosus. Chin Med J (Engl). 2010;123(20):2914-8.         [ Links ]

33. Dumpa V, Northrup V, Bhandari V. Type and timing of ventilation in the first postnatal week is associated with bronchopulmonary dysplasia/death. Am J Perinatol. 2011;28(4):321-30.         [ Links ]

34. Ramanathan R, Sardesai S. Lung protective ventilatory strategies in very low birth weight infants. J Perinatol. 2008;28 Suppl 1:S41-6. Review.         [ Links ]

35. De Paoli AG, Morley C, Davis PG. Nasal CPAP for neonates: what do we know in 2003? Arch Dis Child Fetal Neonatal Ed. 2003;88(3):F168-72.         [ Links ]

36. Meyer M, Mildenhall L, Wong M. Outcomes for infants weighing less than 1000 grams cared for with a nasal continuous positive airway pressure-based strategy. J Paediatr Child Health. 2004;40(1-2):38-41.         [ Links ]

37. Sahni R, Ammari A, Suri MS, Milisavljevic V, Ohira-Kist K, Wung JT, et al. Is the new definition of bronchopulmonary dysplasia more useful? J Perinatol. 2005;25(1):41-6.         [ Links ]

38. Aucott SW. Bronchopulmonary dysplasia: development and progression in the neonatal intensive care unit. Pediatr Allergy Immunol Pulmonol. 2011;24(2):113-8.         [ Links ]

39. Finer NN, Carlo WA, Duara S, Fanaroff AA, Donovan EF, Wright LL, Kandefer S, Poole WK; National Institute of Child Health and Human Development Neonatal Research Network. Delivery room continuous positive airway pressure/positive end-expiratory pressure in extremely low birth weight infants: a feasibility trial. Pediatrics. 2004;114(3):651-7.         [ Links ]

40. Bokodi G, Treszl A, Kovács L, Tulassay T, Vásárhelyi B. Dysplasia: a review. Pediatr Pulmonol. 2007;42(10):952-61. Review.         [ Links ]

41. Jobe AH, Bancalari E. Bronchopulmonary dysplasia. Am J Respir Crit Care Med. 2001;163(7):1723-9.         [ Links ]

42. Freitas BAC, Leão RT, Gomes AP, Siqueira-Batista R. Terapia nutricional e sepse neonatal. Rev Bras Ter Intensiva. 2011;23(4):492-8.         [ Links ]

43. Hakulinen A, Heinonen K, Jokela V, Kiekara O. Occurrence, predictive factors and associated morbidity of bronchopulmonary dysplasia in a preterm birth cohort. J Perinat Med. 1988;16(5-6):437-46.         [ Links ]

 

 

Corresponding author:
Brunnella Alcantara Chagas de Freitas
Departamento de Medicina e Enfermagem da Universidade Federal de Viçosa
Avenida P. H. Rolfs s/n - Campus Universitário
Zip Code: 36571-000 - Viçosa (MG), Brazil
E-mail: brupediatria@gmail.com

Submitted on January 3, 2012
Accepted on May 2, 2012

Conflicts of interest: None.

 

 

This study was conducted at the Department of Medicine and Nursing and the Department of Nutrition and Health, Universidade Federal de Viçosa - UFV - Viçosa (MG), Brazil.