Pulmonary Hypertension in Premature Infants. Sharpening the Tools of Detection

Abstract

measurements, as well as acceptable measurements in more than 1,000 children aged 5-12 years. A comparison of children living in a range of locations in India with those of Indian heritage who were living in London in the United Kingdom revealed significantly higher FEV 1 and FVC (per z-scores relative to reference values derived from Indian populations) in the London residents. However, when the India-resident children were subgrouped into urban, semiurban, and rural areas of residence, it was discovered that the urban-residing children from India had spirometric measures that were indistinguishable from those measured in the London contingent. In contrast, the rural-residing Indian children had FEV 1 and FVC measures that were 0.9 z-scores lower, and the semiurban Indian group had measures 0.5 z-scores lower, than the India urban and London groups. Assuming that the genetically determined physical characteristics relating predicted lung volumes to height, age, and sex are relatively constant for the general population of India, these results suggest strongly that differences in living conditions among these subpopulations have a significant effect on lung development or lung function. This is useful information, as it identifies a population that could hold clues to mechanisms by which environmental conditions may affect lung development in utero or in early life and that may benefit from interventions to improve lung health.The authors also report that the z-FEV 1 /FVC was not significantly different among the subpopulations, suggesting a restrictive (reduced lung size), rather than obstructive, pattern in the nonurban residents. This needs to be confirmed with a measure of total lung capacity (TLC), which would not be possible for population screening but could be attempted in a representative sample of participants. In persons with normal respiratory systems, the primary determinant of FEV 1 is FVC, the primary determinant of FVC is TLC, and the primary determinant of TLC is thoracic volume, which relates to height and chest dimensions. Thus, the surrogate measures (height, age, sex, ethnic heritage) that are used to compute reference ranges for spirometry mostly function as an estimate of TLC. If the actual TLC is significantly different from the expected TLC, this will affect the z-FEV 1 and z-FVC but will not affect the z-FEV 1 /FVC unless the TLC is altered by a process that also affects airway integrity or lung elastic recoil. The alternative scenario that may cause a proportional decrease of FEV 1 and FVC is premature airway closure during forced expiration (2), although this is unlikely in the absence of chronic respiratory symptoms.The authors employed a multivariate model that included family affluence score, exposure to household tobacco smoke, exposure to indoor biomass smoke, z-body weight, and z-body mass index, but these variables were nearly qualitatively associated with place of residence, so none emerged as strong correlates with the spirometric measures. Specific data regarding maternal to...

Maturational Patterns of Systolic Ventricular Deformation Mechanics by Two-Dimensional Speckle-Tracking Echocardiography in Preterm Infants over the First Year of Age

“…19,25,26 In this study we found a significant decrease in RV FWLS and IVS GLS in infants with BPD compared to infants without BPD (uncomplicated preterm infant), which remained significant after adjusting for the gestational age at birth, gender, and postnatal steroid use. In preterm infants with BPD, the magnitude of RV FWLS increased from 32 weeks to one year CA, but remained lower and tracked inferior when compared to infants without BPD by one-year CA, even when they no longer displayed clinical evidence of lung disease with oxygen requirement or respiratory support.…”

“…As highlighted by Farrow et al, this observation suggests that a primary vascular injury coupled with RV dysfunction may occur in some extreme preterm infants, independent of the lung disease. 26 Although we only observed that one infant had echocardiographic signs of PH at one year CA, the infants with PH on their 36 week PMA echocardiograms that returned for a one-year CA follow-up (n=12 of 17, none of which required oxygen or respiratory support at one year CA ) still had decreased RV FWLS and IVS GLS and altered SLS base-to-apex pattern. Interestingly 25% (n=3) of the infants with PH at 36 weeks PMA that returned at one year CA did not carry a diagnosis of BPD and the patterns of altered strain mechanics persisted in this small sub-cohort as well.…”

“…46 Whether this PH is clinically significant alone or predicts long-term morbidity in infants with BPD will require further study. 26 …”

“…19,25 They were assessed in a separate analysis. Since the incidence of PH ranges from 12–25% of infants with BPD 26 , we performed stepwise regression to analyze the influence of PH and BPD on ventricular strain patterns.…”

Pulmonary hypertension in the premature infant

“…One of the implications of this report is that predicting which infants are at risk for the later development of BPD-PH very early in life (36) may be possible. This report underscores the need for screening for PH both early and late in the NICU course, as lung growth and vascular development are interdependent from the beginning of development.…”