Cardiopulmonary Transition in the High Altitude Infant

Niermeyer, Susan

doi:10.1089/152702903322022820

Cited by 72 publications

(51 citation statements)

References 58 publications

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Section: Discussionmentioning

confidence: 99%

“…[9][10][11][12] Breathing patterns and maturation of respiratory control reflexes differ, and the postnatal decline of pulmonary vascular resistance proceeds more gradually. 6,11,13 Genetic factors may also have a role in the pulmonary adaptation to altitude. 14 In infants and children exposed to high altitude, physiological adaptations, such as hyperventilation, polycythemia, increased oxygen extraction, enhanced alveolar growth and increased capillary proliferation, help to maintain adequate oxygen balance.…”

Section: Discussionmentioning

confidence: 99%

“…14 In infants and children exposed to high altitude, physiological adaptations, such as hyperventilation, polycythemia, increased oxygen extraction, enhanced alveolar growth and increased capillary proliferation, help to maintain adequate oxygen balance. 11,15,16 Yet in contrast to older infants and children, there are no data on the effect of altitude on preterm infants with or without BPD, and it is unknown whether similar changes and adaptive mechanisms occur. Potentially, several mechanisms could limit the ability of preterm infants to compensate for the hypoxia of altitude.…”

Section: Discussionmentioning

confidence: 99%

“…Potentially, several mechanisms could limit the ability of preterm infants to compensate for the hypoxia of altitude. Periodic breathing, common in such infants, 17 is increased under hypoxic conditions 18 and at high altitude 11,14 and may lead to hypoventilation and oxygen need. 19 Calculations summarized in the Figure 1 suggest that oxygen may be required solely because of altitude in several US cities, including some not generally considered to be at significant elevations above sea level.…”

Section: Discussionmentioning

confidence: 99%

“…Altitude may accentuate this phenomenon, perhaps through enhancement of periodic breathing. 11,23 As a result, infants with less mature respiratory control mechanisms may be more likely to desaturate during the HOT and require higher concentrations of oxygen. This mechanism is entirely speculative, however, and warrants further investigation.…”

Section: Discussionmentioning

confidence: 99%

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Altitude, oxygen and the definition of bronchopulmonary dysplasia

Britton

2012

J Perinatol

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Objective: The definition of bronchopulmonary dysplasia (BPD) among very-low birth weight (VLBW) infants is based upon oxygen requirement at 36 weeks gestation, but oxygen may be required at altitude because of hypoxia. This study determined the effect of altitude on BPD rates.Study Design: For 63 VLBW infants at high altitude, oxygen concentrations were measured by a hood oxygenation test (HOT) and BPD rates were determined with altitude adjustment.Result: BPD rates before and after altitude adjustment were 71.8 and 26.7%, respectively. Of oxygen-dependent infants analyzed by HOT, 33.3% needed room air. HOT oxygen requirement correlated with gestational age of last apnea episode (r ¼ 0.42, P<0.001).Conclusion: Although BPD rates may be adjusted for altitude with the HOT, the test does not accurately predict clinical oxygen need. Persistent requirement for supplemental oxygen beyond that needed in the HOT may be partially due to immaturity of respiratory control mechanisms.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Altitude, oxygen and the definition of bronchopulmonary dysplasia

Britton

2012

J Perinatol

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Evolutionary adaptation to high altitude: A view from in utero

Julian

Wilson

Moore

2009

American J Hum Biol

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A primary focus within biological anthropology has been to elucidate the processes of evolutionary adaptation. A. Roberto Frisancho helped move anthropology towards more mechanistic explanations of human adaptation by drawing attention to the importance of the functional relevance of human variation. Using the natural laboratory of high altitude, he and others asked whether the unique physiology of indigenous high-altitude residents was the result of acclimatization, developmental plasticity and/or genetic adaptation in response to the high-altitude environment. We approach the question of human adaptation to high altitude from a somewhat unique vantage point; namely, by examining physiological characteristics -pregnancy and pregnancy outcome --that are most closely associated with reproductive fitness. Here we review the potent example of high-altitude native population's resistance to hypoxia-associated reductions in birth weight, which is often associated with higher infant morbidity and mortality at high altitude. With the exception of two recent publications, these comparative birth weight studies have utilized surnames, self-identification and/or linguistic characteristics to assess ancestry, and none have linked 'advantageous' phenotypes to specific genetic variations. Recent advancements in genetic and statistical tools have enabled us to assess individual ancestry with higher resolution, identify the genetic basis of complex phenotypes and to infer the effect of natural selection on specific gene regions. Using these technologies our studies are now directed to determine the genetic variations that underlie the mechanisms by which high-altitude ancestry protects fetal growth and, in turn, to further our understanding of evolutionary processes involved in human adaptation to high altitude. KeywordsPregnancy; hypoxia; fetal growth; birth weight; SNP Studies of human adaptation have long sought to determine whether the unique physiology that characterizes native altitude populations is the result of genetic adaptation to high altitude (defined here as >2500 m). Several unique features of the high-altitude environment make it well suited for studying genetic adaptation. Unlike the majority of environmental stressors such as temperature, malnutrition or disease threats, the hypoxia of high altitude is pervasive in that it affects all residents, all the time. Oxygen, even more than food or water, is essential to human life. But unknown is the extent to which the ability to adapt --that is, the ability to survive and reproduce successfully --to high altitude is due to time-dependent changes that can be acquired by all (or nearly all) persons (i.e., acclimatization), changes Address for correspondence: Lorna G. Moore, PhD Graduate School of Arts and Sciences 1 Medical Center Blvd Wake Forest University Winston-Salem, NC 27157-1001. NIH Public Access Author ManuscriptAm J Hum Biol. Author manuscript; available in PMC 2010 September 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manusc...

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Elevated pulmonary artery pressure among Amhara highlanders in Ethiopia

Hoit

Dalton

Gebremedhin

et al. 2010

American J Hum Biol

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OBJECTIVE Pulmonary arterioles respond to hypoxia with constriction that raises vascular resistance and pulmonary artery blood pressure. The response is sustained indefinitely by the chronic hypoxia of high-altitude residence among highlanders of European and Andean descent, but not Tibetans. The objective of this study was to identify the consequences of lifelong hypoxia exposure for the pulmonary vasculature among Amhara high-altitude natives from Ethiopia. METHODS A three-way static group comparison tested for the effect of Amhara ancestry and high residence altitude on pulmonary hemodynamics measured using echocardiography in samples of 76 healthy adult Amhara lifelong residents at 3700m, 54 Amhara lifelong residents at 1200m, and 46 U.S. low-altitude residents at 282m. RESULTS Amhara at 3700m had average Doppler-estimated pulmonary artery systolic pressure (tricuspid regurgitant gradient) of 27.9 ± 8.4 (SD) mmHg as compared with 21.9 ± 4.0 among Amhara at low altitude and 16.5 ± 3.6 in the U.S. low-altitude reference sample. However, there was no residence altitude effect on pulmonary blood flow or vascular resistance. Amhara ancestry was associated with greater pulmonary artery systolic pressure and pulmonary blood flow, yet lower pulmonary vascular resistance. CONCLUSIONS The Amhara at 3700m had elevated pulmonary artery pressure, but without the elevated pulmonary vascular resistance characteristic of the classic model of the response to long-term hypoxia by the pulmonary vasculature. The elevated pressure among Amhara may be a consequence of high pulmonary blood flow regardless of altitude and represent a newly identified pattern of response.

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Cardiopulmonary Transition in the High Altitude Infant

Cited by 72 publications

References 58 publications

Altitude, oxygen and the definition of bronchopulmonary dysplasia

Altitude, oxygen and the definition of bronchopulmonary dysplasia

Evolutionary adaptation to high altitude: A view from in utero

Elevated pulmonary artery pressure among Amhara highlanders in Ethiopia

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