Shock Notes

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Shock

NOTES NOTES SHOCK SHOCK osms.it/shock PATHOLOGY & CAUSES ▪ Global inadequate tissue perfusion ▫ Extremely low blood pressure (BP) → end-organ failure TYPES ▪ Hypovolemic shock, cardiogenic shock, obstructive shock, distributive shock Hypovolemic Shock ▪ General clinical manifestations ▫ Reduced preload with suspected cause ▪ Variable presentation based on etiology of fluid loss ▪ Hemorrhage, evidence of trauma ▫ Internal bleeding into thoracic/peritoneal/ retroperitoneal space ▪ Nonhemorrhagic fluid loss ▫ Decreased tissue perfusion ▫ Elevated blood urea nitrogen, serum creatinine concentration (non-specific, i.e. seen in all forms of shock) ▫ Abnormal potassium levels ▫ Metabolic acidosis/alkalosis ▫ Hematocrit, serum albumin concentration → reduction in plasma volume increases concentration Cardiogenic Shock ▪ General clinical manifestations ▫ Hypotension, manifestations of pulmonary edema ▪ Subtypes of cardiogenic shock ▫ Myopathic: find specific cause via ECG/ lab values/chest radiograph ▫ Arrhythmogenic: caused by arrythmia Obstructive Shock ▪ General clinical manifestations ▫ Low preload; obstruction of blood flow outside the heart ▫ Cardiac tamponade, pulmonary embolism, tension pneumothorax Figure 18.1 Illustration summarizing the causes and effects of hypovolemic, cardiogenic, and distributive shock. 122 OSMOSIS.ORG
Chapter 18 Shock Distributive Shock ▪ General clinical manifestations ▫ Hypotension without reduced preload, fluid overload ▪ Subtypes of distributive shock ▫ Septic: caused by infection ▫ Anaphylactic: allergic reaction → respiratory distress, vomiting, abdominal pain, chest pain, dysrhythmia, collapse ▫ Neurogenic: pain at site of spinal fracture, evidence of spinal injury (loss of sensation, paralysis, loss of reflexes) ▫ Endocrine: adrenal crisis (nonspecific symptoms, eg. anorexia, nausea, vomiting, abdominal pain, fatigue, lethargy, weakness, fever, confusion, coma); confirmation of adrenal insufficiency RISK FACTORS ▪ Dependent upon type ▪ Septic shock most common in United States, followed by cardiogenic, hypovolemic, other forms of distributive/ obstructive shock ▪ Hypovolemic shock from gastrointestinal (GI) losses/dehydration most common in low-income countries STAGING Initial ▪ Cellular, not clinically apparent Compensatory ▪ Neural, hormonal, biochemical compensation to maintain homeostasis; inadequate perfusion → autonomic nervous system attempts to compensate ▫ Sympathetic nervous system OSMOSIS.ORG 123
vasoconstriction, ↑ contractility ▫ Release of catecholamines, vasopressin, angiotensin II → ↑ vasoconstriction, ↑ retention water, sodium → ↑ SVR, ↑ blood volume → ↑ BP → ↑ perfusion Progressive ▪ Compensation fails, requires aggressive interventions to prevent multiple organ dysfunction syndrome Irreversible ▪ Decreased perfusion (vasoconstriction, decreased cardiac output) → anaerobic metabolism; profound hypotension, hypoxemia, organ failure; recovery unlikely SIGNS & SYMPTOMS ▪ Altered mental state, decreased peripheral pulse, tachycardia, hypotension ▪ Varies by type and subtype of shock (see table below) DIAGNOSIS DIAGNOSTIC IMAGING Chest radiography ▪ Clear in hypovolemic/obstructive shock from pulmonary embolism ▪ Pneumonia ▫ Septic shock ▪ Pneumothorax ▫ Obstructive shock ▪ Pulmonary edema ▫ Cardiogenic shock/ARDS Pulmonary artery catheterization ▪ Hemodynamic measurements can be helpful ▪ Measure cardiac output, systemic vascular resistance, pulmonary artery occlusion pressure, right atrial pressure, mixed venous oxyhemoglobin saturation ▪ Rarely necessary to identify etiology of shock Ultrasound/echocardiography ▪ Allows visualization of altered cardiac function 124 OSMOSIS.ORG ▪ Preserved/hyperdynamic left ventricle = distributive shock ▪ Point-of-care ultrasond ▫ Examination of heart → cause of cardiogenic shock, obstructive shock Focused assessment and sonography for trauma (FAST) ▪ Fast ultrasound examination for hemopericardium, intra-abdominal bleeding; rule out/in hypovolemic shock Hemodynamic monitoring ▪ Via central venous catheters ▪ Elevated central venous pressure, low mixed venous oxygen saturation = cardiogenic shock LAB RESULTS Elevated serum lactate ▪ Early indicator, reflective of poor tissue perfusion Renal, liver function tests ▪ Elevated blood urea nitrogen (BUN), creatinine, transaminases indicate endorgan damage ▫ May help point to cause (acute hepatitis, chronic cirrhosis) Coagulation studies, D-dimer level ▪ Elevated fibrin split products, elevated D-dimer level, low fibrinogen level = severe shock Cardiac enzymes, natriuretic peptides ▪ Elevated troponin, creatine phosphokinase, N-terminal pro-brain natriuretic peptide, brain natriuretic peptide = cardiogenic shock due to ischemia/pulmonary embolism Complete blood count, differential ▪ High hematocrit ▫ Hemoconcentration from nonhemorrhagic hypovolemic shock ▪ Anemia, bleeding ▫ Hemorrhagic shock ▪ Elevated eosinophil ▫ Allergy, anaphylactic shock ▪ Leukocytosis ▫ Septic shock, not specific; more common
Chapter 18 Shock in septic shock, may also occur in other types of shock as sign of poor prognosis Coagulation studies, D-dimer level ▪ Elevated prothrombin time, international normalized ratio, activated partial thromboplastin time ▫ Septic shock, other issues (e.g. sepsis, systemic inflammatory response syndrome); elevated D-dimer levels common in septic shock Peripheral O2 sat via pulse oximetry ▪ Hypoxemia ▫ Obstructive, cardiogenic shock Urinalysis ▪ Infection, septic shock Material gram stain from infection sites ▪ Septic shock Blood culture ▪ identifies causative microbe in case of septic shock; directs targeted antibiotic therapy OTHER DIAGNOSTICS History & physical ▪ Low blood pressure, tachycardia, tachypnea, signs of poor end-organ perfusion (low urine output, confusion, loss of consciousness), weak pulse, cool skin, metabolic acidosis, hyperlactatemia Shock index ▪ Heart rate divided by systolic pressure ▫ Normal range 0.5–0.8 ▫ If index higher, increased suspicion of underlying state of shock ▫ Most useful for isolated hypotension/ tachycardia ECG ▪ Arrhythmia, ST segment changes consistent with ischemia ▪ Low-voltage ECG ▫ Pericardial effusion ▪ Arrhythmia ▫ Arrhythmogenic cardiogenic shock ▪ Ischemia ▫ Myopathic cardiogenic shock OSMOSIS.ORG 125
MNEMONIC: ABCDE Treatment for shock Airway: ensure clear airway, possibly intubate Breathing: assist individual in breathing, mechanical ventilation/sedation Circulation: administer fluids (e.g. isotonic crystalloid) Delivery of oxygen: monitor lactate levels Endpoint resuscitation (specific to septic shock) 126 OSMOSIS.ORG TREATMENT ▪ See chart for a detailed summary of treatments for different forms of shock OTHER INTERVENTIONS Surviving sepsis campaign guidelines ▪ End resuscitation when urine output 0.5ml/ kg/hr, central venous pressure (CVP) 8–12 mmHg, mean arterial pressure (MAP) 65–90mmHg, central venous oxygen concentration > 70%, normalize lactate levels ▫ CVP 8–12mmHg (recent literature shows CVP poorly predicts fluid responsiveness, poor marker of adequate resuscitation)

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Shock essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Shock by visiting the associated Learn Page.