Physiologic Basis for the Management of Acute Respiratory ：对于急性呼吸道管理的生理基础.ppt

Physiologic Basis for the Management of Acute Respiratory Disorders in the Newborn Marc Collin, MD Developmental Anatomy Alveoli-developed by 25th week -increase in # until 8 yr. -from 20 to 300 million -surface area: 2.8 m2 @ birth 32 m2 @ 8 yr. 75 m2 @ adulthood -diameter: 150- 300 um(NB-Adult) Developmental Anatomy Airways- cartilaginous - relatively weak in infancy - dynamic compression - bronchiolitis (RSV) - RAD - crying! Developmental Anatomy airways enlarge in diameter/length distal airways lag in first 5 yr. high peripheral resistance in infancy Resistance = 1/R4 Pulmonary Physiology Compliance = Change in Volume Change in Pressure Static Lung Volumes Mechanics of Infant v. Adult Lung Pulmonary Physiology Alveoli at birth fluid-filled v. air-filled v. air-liquid interface pressures up to 80 cm H2O @ birth alveolar rupture Pressure-Volume Curves after Air v. Liquid Lung Expansion Pulmonary Physiology ? LaPlace relationship: P = 2T/R P= distending pressure T= wall tension R= radius (alveolar) Pressure-Volume Curves of First 3 Breaths Developmental Biochemistry of Alveoli History: Avery Mead-1959 - RDS secondary to surfactant deficiency - Treatment: CPAP Surfactant Phospholipids - phosphatidylcholine - phosphatidylglycerol Surfactant proteins - A, B, C Surfactant Components Surfactant Type II alveolar epithelial cells