Condition of severe impairment of tissue perfusion leading to cellular injury and dysfunction. Rapid recognition and treatment are essential to prevent irreversible organ damage and death. Common causes are listed in Table 11-1.
Approach to the Patient: Shock Obtain history for underlying causes, including cardiac disease (coronary disease, heart failure, pericardial disease), recent fever or infection leading to sepsis, drug effects (e.g., excess diuretics or antihypertensives), conditions leading to pulmonary embolism (Chap. 133. Pulmonary Thromboembolism and Deep-Vein Thrombosis), and potential sources of bleeding. |
Jugular veins are flat in oligemic or distributive (septic) shock; jugular venous distention (JVD) suggests cardiogenic shock; JVD in presence of paradoxical pulse (Chap. 110. Physical Examination of the Heart) may reflect cardiac tamponade (Chap. 116. Pericardial Disease). Check for asymmetry of pulses (aortic dissectionChap. 125. Diseases of the Aorta). Assess for evidence of heart failure (Chap. 124. Heart Failure and Cor Pulmonale), murmurs of aortic stenosis, acute mitral or aortic regurgitation, and ventricular septal defect. Tenderness or rebound in abdomen may indicate peritonitis or pancreatitis; high-pitched bowel sounds suggest intestinal obstruction. Perform stool guaiac to rule out GI bleeding.
Fever and chills typically accompany septic shock. Sepsis may not cause fever in elderly, uremic, or alcoholic pts. Skin lesions may suggest specific pathogens in septic shock: petechiae or purpura (Neisseria meningitidis or Haemophilus influenzae), ecthyma gangrenosum (Pseudomonas aeruginosa), generalized erythroderma (toxic shock due to Staphylococcus aureus or Streptococcus pyogenes).
Obtain hematocrit, WBC, electrolytes, platelet count, PT, PTT, DIC screen, electrolytes. Arterial blood gas usually shows metabolic acidosis (in septic shock, respiratory alkalosis precedes metabolic acidosis). If sepsis suspected, draw blood cultures, perform urinalysis, and obtain Gram stain and cultures of sputum, urine, and other suspected sites.
Obtain ECG (myocardial ischemia or acute arrhythmia) and chest x-ray (heart failure, tension pneumothorax, pneumonia). Echocardiogram is often helpful (cardiac tamponade, left/right ventricular dysfunction, aortic dissection).
CVP or pulmonary capillary wedge (PCW) pressure measurements may be necessary to distinguish between different categories of shock (Table 11-2): Mean PCW <6 mmHg suggests oligemic or distributive shock; PCW >20 mmHg suggests left ventricular failure. Cardiac output (thermodilution) is decreased in cardiogenic and oligemic shock, and usually increased initially in septic shock.
Treatment: Shock Aimed at rapid improvement of tissue hypoperfusion and respiratory impairment (Fig. 11-1):
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Section 2. Medical Emergencies