NMS. Surgery

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Chapter 1 ♦ Principles of Surgical Physiology

(2) A chest tube placed on the affected side relieves the problem. b. Cardiac tamponade: Fluid accumulates around the heart in the pericardium. (1) The increased pressure in the pericardial sac impairs venous return into the right atrium, decreasing CO. (2) Treatment: Drain the pericardium to allow venous return. c. Pulmonary embolism: Blocks blood flow through the pulmonary artery, resulting in decreased CO and hypoxia. Treatment ranges from anticoagulation through operative pulmonary thrombectomy. d. Abdominal compartment syndrome: Increased pressure in the abdomen that compresses the inferior vena cava and decreases preload. e. Mechanical ventilation with excessive PEEP: Increased intrathoracic pressure may lead to obstructive shock. F. Miscellaneous shock: Often distributive (reduced afterload ) in nature (e.g., anaphylaxis, adrenal insufficiency). 1. Cyanide toxicity impairs oxygen usage directly. 2. In some patients (e.g., Jehovah’s Witnesses, who do not accept blood transfusions for religious reasons), the Hgb level is so low that it causes shock and poor oxygen delivery. 3. Severe hypoxia from respiratory failure, or ALI/ARDS can also lead to shock ( oxygen saturation ). Quick Cuts • SvO 2 is one of the best parameters to assess for shock. • Vasopressors are typically only administered in the ICU. • Norepinephrine is the first choice in septic shock. • Six variables to improve oxygen delivery are hemoglobin, SaO 2 , heart rate, preload, contractility, and afterload. • Bleeding hypovolemic patients should get blood. • Resuscitate bleeding patients with 1:1:1 blood:FFP:platelets.