手术前后的呼吸衰竭.ppt

手術前後呼吸衰竭Perioperative Respiratory Failure 重症課程 2004.07.01. Key Manifestations Pulmonary edema (肺積水, 水分太多) Atelectasis (肺塌陷, 容量減少) Alveolar hypoventilation (換氣不足) Aspiration (異物吸入) Pulmonary Edema Microvascular hydrostatic pressure “normal” response trauma ? ADH, aldosterone ? conserve water Fluid overload Pulmonary capillary permeability Unrecognized sepsis Lung Edema Atelectasis (collapse) Concepts FRC Closing volume Perioperative Atelectasis Reduced FRC Increased closing volume Lung Volumes Functional residual capacity (FRC) is the volume of air in the lungs at the end of a normal expiration. FRC is determined by a balance between the inward elastic forces of the lung and the outward forces of the respiratory cage (mostly due to muscle tone). FRC falls with lying supine, obesity, pregnancy and anaesthesia, though not with age. The FRC is of particularly importance to anaesthetists because: During apnoea it is the reservoir to supply oxygen to the blood As it falls the distribution of ventilation within the lungs changes leading to mismatching with pulmonary blood flow If it falls below a certain volume (the closing capacity), airway closure occurs leading to shunt (see later - Ventilation/perfusion/shunt) Lung Collapse Risk Factors of Atelectasis Atelectasis Diaphragm dysfunction Upper abdominal surgery Complex effects Fall in vital capacity, decrease in FRC, increase in closing volume… A major component of perioperative respiratory failure Diaphragm Dysfunction Alveolar Hypoventilation Impairment of ventilation Pain Peritonitis Anesthesia CNS injury Increased metabolic requirement Aspiration Gastric acid aspiration Variable presentation One of the major causes of morbidity and mortality The Treatment of Acid Aspiration rapid removal of debris placement of a nasogastric tube oxygen administration and mechanical ventation bronchodilator therapy maintenance of normovolemia treatment of pnemonia Predicting and Preventing Risk factors ? correction Lu