病理生理学呼吸系统.ppt

A previously healthy 23-year-old male sustained numerous traumatic crush, burn, and smoke inhalation injuries during a landing accident in an airplane. His initial B.P. was 80/50 mmHg, and he was immediately infused with saline at the maximal rate. In the ER he was intubated and had no signs of pneumothorax. His orthopedic injuries and burns were treated. The ventilator was placed on the assist-control mode with the initial settings of inspired O2 concentration at 40%, respiration rate at 12/min, and tidal volume at 900 ml. Arterial blood gas measurements were: pH = 7.47, PCO2 of 33 mmHg, and PO2 of 62 mmHg. Clinical Case 当前第31页\共有43页\编于星期五\20点 24 hrs. after admission, the patient becomes agitated and his respiration rate increased to 30/min. His minute ventilation also increased from 8.5 l/min to 20 l/min. Airway pressure increased from 18 to 65 cm H2O. Repeat arterial blood gas measurement of PO2 indicated 35 mmHg and chest x-ray now showed diffuse infiltrates in a "white out" pattern. Clinical Case 当前第32页\共有43页\编于星期五\20点 The diagnosis of ARDS is contingent upon 5 factors: 1. Hypoxemia, 2. Diffuse pulmonary infiltrates on radiography, 3. Absence of congestive heart failure, 4. Decreased lung compliance (effective static compliance < 25-35 ml/cm H2O), and 5. Appropriate antecedent history. Currently, there are no specific laboratory tests for ARDS. A definitive diagnosis is made when these signs and symptoms are linked with diffuse alveolar damage. Clinical Case 当前第33页\共有43页\编于星期五\20点 急性呼吸窘迫综合征(ARDS)的概念及发生机制? 问题 ： 当前第34页\共有43页\编于星期五\20点 二、呼衰时机体功能和代谢变化 Functional and Metabolic Change in Respiratory Failure （一）酸碱平衡紊乱(acid-base balance disturbance)和电解质变化 呼酸: Ⅱ型呼衰 CO2潴留 血 K+ , 血 Cl- 呼碱：I型呼衰 肺过度通气 血 K+ , 血 Cl- 代酸：严重缺氧 无氧代谢 乳酸 当前第35页\共有43页\编于星期五\20点 （二）呼吸系统的变化(Changes in Respiratory System) 呼吸调节(Regulation of Respiration) 的变化 外周化学 感受器 中枢化学 感受器 呼吸 加深加快 抑制 呼吸中枢 PaO2↓ <60 mmHg PaCO2↑ >50 m