Higher Altitude and Risk of Bronchopulmonary Dysplasia among Preterm Infants

Abstract

Objective To assess the association between altitudes of neonatal intensive care units (NICU) and the rate of bronchopulmonary dysplasia (BPD) and BPD/death in very preterm infants.

Study Design Data from infants born at <33 weeks' gestation admitted to Canadian Neonatal Network during 2008 and 2009 were analyzed. The associations between the altitude of NICU and the BPD and altitude and BPD/death were determined using logistic regression models.

Results Of 7551 eligible infants, 1540 (20%) were admitted to NICUs at an altitude > 400 m, 3661 (48%) between 86 and 400 m, 2350 (31%) at ≤85 m. The incidences of BPD (21.7% versus 17.2%) and BPD/death (26.2% versus 23.0%) were significantly higher in the infants admitted to NICUs at >400 m altitude versus those ≤400 m altitude (p < 0.01). In multivariable analyses, the adjusted odds ratio was 1.81 (95% confidence interval [CI] 1.05 to 3.12) for BPD and 1.79 (95% CI 1.12 to 2.85) for BPD/death among infants admitted to NICUs at altitude > 400 m compared with NICUs at altitude ≤ 400 m. For each 100-m increase in altitude, the odds increased by 8% for BPD (95% CI 4 to 13%) and 9% for BPD/death (95% CI 5 to 13%); however, the increase was mainly due to increase in BPD.

Conclusion For very preterm infants, higher altitude of NICUs increased the risk of BPD.

Keywords

infant - premature - altitude - chronic lung disease - morbidity

• References

• 1 Van Marter LJ. Epidemiology of bronchopulmonary dysplasia. Semin Fetal Neonatal Med 2009; 14: 358-366
• 2 Jobe AH, Ikegami M. Mechanisms initiating lung injury in the preterm. Early Hum Dev 1998; 53: 81-94
• 3 Mosca F, Colnaghi M, Fumagalli M. BPD: old and new problems. J Matern Fetal Neonatal Med 2011; 24 (Suppl. 01) 80-82
• 4 Shah PS. Current perspectives on the prevention and management of chronic lung disease in preterm infants. Paediatr Drugs 2003; 5: 463-480
• 5 Majnemer A, Riley P, Shevell M, Birnbaum R, Greenstone H, Coates AL. Severe bronchopulmonary dysplasia increases risk for later neurological and motor sequelae in preterm survivors. Dev Med Child Neurol 2000; 42: 53-60
• 6 Vohr BR, Coll CG, Lobato D, Yunis KA, O'Dea C, Oh W. Neurodevelopmental and medical status of low-birthweight survivors of bronchopulmonary dysplasia at 10 to 12 years of age. Dev Med Child Neurol 1991; 33: 690-697
• 7 Cogo A, Fischer R, Schoene R. Respiratory diseases and high altitude. High Alt Med Biol 2004; 5: 435-444
• 8 Moore LG. Altitude-aggravated illness: examples from pregnancy and prenatal life. Ann Emerg Med 1987; 16: 965-973
• 9 Keyes LE, Armaza JF, Niermeyer S, Vargas E, Young DA, Moore LG. Intrauterine growth restriction, preeclampsia, and intrauterine mortality at high altitude in Bolivia. Pediatr Res 2003; 54: 20-25
• 10 Palmer SK, Moore LG, Young D, Cregger B, Berman JC, Zamudio S. Altered blood pressure course during normal pregnancy and increased preeclampsia at high altitude (3100 meters) in Colorado. Am J Obstet Gynecol 1999; 180: 1161-1168
• 11 Jensen GM, Moore LG. The effect of high altitude and other risk factors on birthweight: independent or interactive effects?. Am J Public Health 1997; 87: 1003-1007
• 12 Shennan AT, Dunn MS, Ohlsson A, Lennox K, Hoskins EM. Abnormal pulmonary outcomes in premature infants: prediction from oxygen requirement in the neonatal period. Pediatrics 1988; 82: 527-532
• 13 Kramer MS, Platt RW, Wen SW , et al; Fetal/Infant Health Study Group of the Canadian Perinatal Surveillance System. A new and improved population-based Canadian reference for birth weight for gestational age. Pediatrics 2001; 108: E35
• 14 Lichty JA, Ting RY, Bruns PD, Dyar E. Studies of babies born at high altitudes. I. Relation of altitude to birth weight. AMA J Dis Child 1957; 93: 666-669
• 15 Mahfouz AA, al-Erian RA. Hypertension in Asir region, southwestern Saudi Arabia: an epidemiologic study. Southeast Asian J Trop Med Public Health 1993; 24: 284-286
• 16 Moore LG, Newberry MA, Freeby GM, Crnic LS. Increased incidence of neonatal hyperbilirubinemia at 3,100 m in Colorado. Am J Dis Child 1984; 138: 157-161
• 17 Niermeyer S. Cardiopulmonary transition in the high altitude infant. High Alt Med Biol 2003; 4: 225-239
• 18 Samuels MP. The effects of flight and altitude. Arch Dis Child 2004; 89: 448-455
• 19 Britton JR. Altitude, oxygen and the definition of bronchopulmonary dysplasia. J Perinatol 2012; ; February 16 (Epub ahead of print)
• 20 Walsh MC, Yao Q, Gettner P , et al; National Institute of Child Health and Human Development Neonatal Research Network. Impact of a physiologic definition on bronchopulmonary dysplasia rates. Pediatrics 2004; 114: 1305-1311
• 21 Ravert P, Detwiler TL, Dickinson JK. Mean oxygen saturation in well neonates at altitudes between 4498 and 8150 feet. Adv Neonatal Care 2011; 11: 412-417
• 22 Thilo EH, Park-Moore B, Berman ER, Carson BS. Oxygen saturation by pulse oximetry in healthy infants at an altitude of 1610 m (5280 ft). What is normal?. Am J Dis Child 1991; 145: 1137-1140
• 23 Białkowski J, Głowacki J, Zabal C , et al. Patent ductus arteriosus at low and high altitudes: anatomical and haemodynamic features and their implications for transcatheter closure. Kardiol Pol 2011; 69: 431-436
• 24 Carballo C, Foucar K, Swanson P, Papile LA, Watterberg KL. Effect of high altitude on neutrophil counts in newborn infants. J Pediatr 1991; 119: 464-466
• 25 Lambert RM, Baer VL, Wiedmeier SE, Henry E, Burnett J, Christensen RD. Isolated elevated blood neutrophil concentration at altitude does not require NICU admission if appropriate reference ranges are used. J Perinatol 2009; 29: 822-825