小儿麻醉2ppt整理.ppt

Pediatric Anesthesia Department of anesthesiology Cui Xiao Guang Neonates: 0–1 months Infants: 1–12 months Toddlers: 1–3 years small children: 4–12 years DEVELOPMENTAL PHYSIOLOGY OF THE INFANT The pulmonary system 1 The relatively large size of the infants tongue The larynx is located higher in the neck The epiglottis is shaped differently, being short and stubby The vocal cords are angled The infant larynx is funnel shaped, the narrowest portion occurring at the cricoid cartilage: uncuffed endotracheal tubes; patients younger than 6 years. The pulmonary system 2 Alveoli increase in number and size until the child is approximately 8 years old. Functional residural capacity (FRC): the same with adult; induction and palinesthesia of anesthesia is rapid A-aDO2 is larger: functional airway closure Limits oxygen reserves: hypoxemia. The work of breathing: (In premature infants) three times of adults, increased by cold stress or some degree of airway obstruction. RR: two times of adults The pulmonary system 3 Tidal volume(VT) is little; physiological dead space is 30% of VT Airway resistance increasing: secretion, upper airway infection Diaphragmatic and intercostal muscles do not achieve the adult configuration of type I muscle fibers until the child 2 years old: apnea or carbon dioxide retention and respiratory failure. Infants have often been described as obligate nasal breathers: 5 months of age. The Cardiovascular System1 In uterus: foramen ovale, ductus arteriosus (right→left) At birth: the fetal circulation becomes an adult-type circulation.-- transitional circulation Prolonged transitional circulation: prematurity, infection, acidosis, pulmonary disease resulting in hypercarbia or hypoxemia (aspiration of meconium), hypothermia, congenital heart disease. The Cardiovascular System2 The myocardial structure of the heart is less developed, produce less compliant ventricles This developmenta