Neonatal and Pediatric Respiratory Care Presentation

Neonatal and Pediatric Respiratory Care Presentation. Embryonic Development of the Lung A. Placental Gas Exchange: 1. The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination and gas exchange via the mother’s blood supply. 2. The placenta functions as a feto-maternal organ with two components: the fetal placenta, which develops from the same blastocyst that form the fetus, and the maternal placenta, which develops from the maternal uterine tissue. I. Embryonic Development of the Lung B. Development of the Fetal Heart: 1. When the heart first develops, it’s nothing more than a tube formed from the fusion of two other tubes. 2. By day 22 or 23 after conception, which is week five of pregnancy, the heart begins to beat and can be seen on vaginal ultrasound as a tiny flicker. 3. The developing heart, nothing more than a tube, consist of 3 layers and 3 specific areas. 4. The three areas, the cranial, caudal and bulbis cordis, develop into different parts of the aorta, the largest artery in the body, and the ventricles. 5. The layers, the cardiac jelly and cardiac mantle layers, of which there are two, will differentiate into the myometrium and epicardium of the heart. I. Embryonic Development of the Lung C. Development of the Fetal Lung: 1. Week 4 of gestation: Lung starts to form as an outpouching of the esophagus. 2. Week 7 of gestation: Diaphragm starts to form. 3. Week 10 of gestation: Cartilaginous rings of the trachea and lymphatic of the respiratory system start to form. 4. Week 22-24 of gestation: Significant development of all cartilaginous support of the conducting airways is developed. 5. Week 26-28 of gestation: Alveolar ducts and sacs have developed and alveolar type II cells begin to appear. The number of alveoli necessary to support extra-uterine life is now present. 6. At normal birth: The number of alveoli is about 24 millions. Alveoli continue to develop after birth until there are about 300 millions alveoli at adulthood. I. Embryonic Development of the Lung D. Surface Tension and Surfactant Development: 1. The first appearance of surfactant is between 26-28 weeks if gestation. At this time, lecithin and sphingomyelin appear in the pulmonary and amniotic fluid. 2. as gestation proceeds, the volume of lecithin in the pulmonary fluid increases, whereas sphingomyelin levels relatively constant. 3. At about 35 weeks of gestation, lecithin levels increase significantly. 4. L/S ratios can be determined intrauterinely by analysis of amniotic fluid or amniocentesis. L/S ratios interpretation: a. L/S ratios of 2:1 – indicative of pulmonary maturity; can support extrauterine life. b. L/S ratios of < 2:1 – incidence of development of respiratory distress syndrome increases. c. L/S ratios of < 1:1 – incompatible with extrauterine existence. I. Embryonic Development of the Lung D. Surface Tension and Surfactant Development: 5. Surface tension is the cohesive forces of a fluid that tends to hold the walls of the alveoli together in a partially collapsed newborn’s lungs. 6. Laplace’s Law or Laplace Equation states that as the radius of the bubble (or in this case, the alveoli) decreases, the surface tension increases.