FIGURE LEGENDS
Figure 1. Demonstration of surface tension by C.V. Boys (4). Right, when
a brush is wetted and held in the air, the air- liquid interfaces causes
the bristles of the brush to attract one another and stick together.
However, when a brush is dry and held in the air, the lack of an air
liquid interface allows the bristles to remain separate (Left).
Similarly, when a brush is completely submerged in water, the lack of an
air liquid interface allows the bristles to remain separate (Center).
Figure 2. Demonstration of the Law of LaPlace by C.V. Boys (4). Since
the LaPlace equation states P = 4T/r, bubbles of smaller radii have
higher pressure and air will flow from the smaller bubble to the larger
bubble.
Figure 3. Demonstration of the role of surfactant in reducing surface
tension in lung extracts by Avery and Mead (5). Lung extracts from a
2990g infant (A) and an adult (B) have lower surface tension than
extracts from a 480g infant (C) and a 3300g infant with hyaline membrane
disease. The positive slope of the surface tension/area curve indicates
the essential role of surfactant in lowering surface tension to a
greater extent when the area of the surface (and therefore the radius of
the alveolus) is compressed due to its higher concentration. Unlike
other lipid “soaps,” surfactant remains on the surface and does not go
into the aqueous phase as the surface is compressed.
Figure 4. Front page of Boston Globe, August 8, 1963. Report of the
respiratory illness of the son of President and Mrs. Kennedy, born at 34
½ weeks gestation, due to neonatal respiratory distress syndrome
(hyaline membrane disease)
Figure 5. Stage 1 BPD (Hyaline Membrane disease). Radiographic
appearance of ground glass infiltrates and air bronchograms, and
pathology showing sloughed hyaline membranes in alveoli and a small
bronchus (From (1)).
Figure 6. Stage 3 BPD. Radiographic appearance of muti-loculated cysts
and pathology showing bronchiolar metaplasia and peribronchiolar smooth
muscle hyperplasia (From (1))
Figure 7. Schematic of an early CPAP system, “bubble CPAP.” Constant
positive airway pressure is adjusted by increasing flow through the
nasal cannula until bubbles appear in the container with the distal end
of the cannula. The degree of CPAP is determined by the depth of the
cannula under the water. (From (21)).
Figure 8. A graphic representation of the multi-system nature of BPD,
and how pathology of various organ systems affect one another. For
example, the arrow from Pulmonary to Nutrition indicates that the
increased work of breathing due to abnormal lung mechanics steals
calories required for growth, whereas the arrow from Nutrition to
Pulmonary indicates that under-nutrition affects respiratory muscles,
pulmonary parenchymal and airway growth, and ultimately repair of
damaged lung. (59)