Postmortem lung volume/body weight standards for term and preterm infants

Abstract

Assessment of lung growth is a critical component of the perinatal autopsy. Increased lung liquid content may lead to overestimation of lung growth based on (wet) lung weight. In contrast, lung volume is not influenced by intraalveolar lung liquid. Our aim was to establish age-specific reference values for postmortem lung volume/BW in preterm and term infants. We performed a retrospective analysis of fetuses/infants (16-41 weeks' gestation) without (N = 134) or with (N = 79) risk factors for pulmonary hypoplasia. Lungs were inflated at standardized pressure and volumes determined by water immersion method. Lung volume increased 11-fold between 16 and 41 weeks' gestation, concomitant with a 16-fold increase in BW. Mean lung volume/BW remained constant at 33-34 ml/kg between 16 and 31 weeks' gestation and decreased to 23.4 ml/kg at term. Lung volume/BW of infants with severe risk factors (renal anomalies, diaphragmatic hernia) was significantly lower than age-matched standards. In this group, all fetuses/infants diagnosed as having lung hypoplasia by lung volume/BW also had lung hypoplasia LW/BW standards. However, in infants with "softer" risk factors (rupture of membranes, chromosomal anomalies), 5/26 cases diagnosed with lung hypoplasia based on lung volume/BW had normal LW/BW ratios. In these discrepant cases, lung sections showed significant inflammation and edema, likely accounting for increased wet lung weight. In conclusion, we determined age-specific lung volume/BW reference values for preterm and term infants. In selected situations assessment of lung volume/BW may represent a useful complementary tool to LW/BW for postmortem evaluation of lung size.

Pulmonary Effects of Prolonged Oligohydramnios following Mid-Trimester Rupture of the Membranes – Antenatal and Postnatal Management

“…The gold standard to confirm pulmonary hypoplasia is a lung to body weight ratio of less than 0.015 at postmortem [55] with reduced radial alveolar count or total DNA count [7] . Characteristic findings on the chest radiograph are of a small bellshaped chest with raised hemi-diaphragms and clear lung fields, although 'clear lung fields' may be masked by radiographic signs of respiratory distress in prematurely born infants.…”

Stretch regulates expression and binding of chymotrypsin‐like elastase 1 in the postnatal lung

“…Throughout prenatal and postnatal life, lung morphogenesis and repair occur as lung tissues are subjected to the dynamic expansion and compression of the respiratory cycle. Even before birth, fetal lung stretch is critical for lung morphogenesis as evidenced by the lung hypoplasia associated with congenital diaphragmatic hernia (1) and oligohydramnios (2). In congenital diaphragmatic hernia, lung growth can be partially restored by in utero lung distention using temporary tracheal occlusion (1).…”

Congenital Diaphragmatic Hernia

“…Pulmonary hypoplasia is defined as incomplete development of the lungs with decreased bronchopulmonary segments and diminished alveolar septation [11]. Incomplete development results in a decreased total lung volume.…”