What are the key points to cover in a 30-minute seminar on shock management in an emergency medicine department?

Shock Management Seminar for Emergency Medicine Department

Classification of Shock: Four Primary Categories

Shock is defined by sustained systolic blood pressure <90 mmHg for ≥30 minutes with evidence of end-organ hypoperfusion (elevated lactate, altered mental status, cold extremities, or decreased urine output), and must be classified into one of four phenotypes to guide treatment: hypovolemic, distributive (septic), cardiogenic, or obstructive. 1, 2

• Hypovolemic shock: Intravascular volume loss requiring fluid replacement 2
• Distributive shock: Pathological redistribution of blood volume (sepsis most common) requiring vasoconstrictors plus fluids 2
• Cardiogenic shock: Primary cardiac dysfunction requiring inotropes/mechanical support 2
• Obstructive shock: Elevated resistance from mechanical blockage requiring immediate intervention 2

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First Hour Resuscitation: The Golden Hour

Within 60 minutes, achieve capillary refill ≤2 seconds, normalized heart rate, and systolic blood pressure ≥90 mmHg in adults. 1

Immediate Actions for All Shock Types

• Administer 20 mL/kg boluses of isotonic crystalloid (normal saline or lactated Ringer's) up to and exceeding 60 mL/kg until perfusion improves or fluid overload develops. 1
• Obtain ECG and echocardiography immediately to identify shock phenotype and guide management 3, 1
• Establish invasive arterial line for continuous blood pressure monitoring 3, 1
• Monitor capillary refill, mental status, urine output (target >0.5 mL/kg/hr), and lactate levels 4, 1

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Septic/Distributive Shock Management

Norepinephrine is the first-line vasopressor after appropriate fluid resuscitation, targeting mean arterial pressure ≥65 mmHg. 1

Initial Resuscitation Protocol

• Administer at least 30 mL/kg IV crystalloid within the first 3 hours of sepsis-induced hypoperfusion. 4
• Begin empiric antibiotics within 1 hour of identifying severe sepsis; obtain blood cultures before antibiotics but do not delay administration 4
• Reassess hemodynamic status frequently using clinical examination, heart rate, blood pressure, oxygen saturation, respiratory rate, temperature, and urine output 4

Vasopressor Selection

• Start norepinephrine as first-line agent over dopamine due to lower arrhythmia risk. 4, 1
• Epinephrine may be added if norepinephrine alone is insufficient 5, 6
• Target ScvO2 ≥70% and cardiac index between 3.3-6.0 L/min/m² in pediatric patients 4

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Cardiogenic Shock Management

Cardiogenic shock is defined by hypotension (SBP <90 mmHg) despite adequate filling status plus signs of hypoperfusion: oliguria, cold peripheries, altered mental status, lactate >2 mmol/L, metabolic acidosis, or SvO2 <65%. 4

Immediate Assessment and Monitoring

• Perform ECG and echocardiography immediately in all suspected cases 4, 3
• Establish invasive arterial line monitoring 4, 3
• Consider pulmonary artery catheter for refractory shock to measure cardiac index, PCWP, and cardiac power output 4, 3, 1

Pharmacological Management

• Attempt fluid challenge (200 mL saline or Ringer's lactate over 15-30 minutes) first if no overt fluid overload is present. 4
• Dobutamine (2-20 mcg/kg/min) is first-line for myocardial dysfunction with adequate blood pressure. 3, 1
• Use norepinephrine over dopamine if vasopressor support is needed to maintain systolic blood pressure. 4
• Levosimendan may be considered, especially in patients on beta-blockers 4, 3

Mechanical Circulatory Support Criteria

• Consider mechanical circulatory support when cardiac index <2.2 L/min/m², cardiac power output <0.6 W, and elevated lactate persist despite initial therapy. 3
• Transfer immediately to tertiary center with 24/7 cardiac catheterization and mechanical circulatory support capabilities 4
• Intraaortic balloon pump is not routinely recommended 4

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Hypovolemic/Hemorrhagic Shock Management

Initiate crystalloid resuscitation immediately and apply isotonic crystalloids or albumin in 20 mL/kg boluses over 5-10 minutes, titrated to reverse hypotension and restore perfusion. 4

Trauma-Specific Considerations

• Avoid hypotonic solutions like Ringer's lactate in patients with severe head trauma 4
• Implement damage control surgery for deep hemorrhagic shock with ongoing bleeding, coagulopathy, hypothermia, or acidosis 4
• Perform immediate pelvic ring closure and stabilization for pelvic ring disruption with hemorrhagic shock 4

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Obstructive Shock: Reversible Causes

Immediately evaluate for and reverse pneumothorax, pericardial tamponade, pulmonary embolism, or tension physiology in patients with refractory shock. 4, 1

• Consider endocrine emergencies (hypoadrenalism, hypothyroidism) in refractory cases 4
• Evaluate for intra-abdominal hypertension in select patients 4, 1

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Advanced Hemodynamic Monitoring

Use pulmonary artery catheter, transpulmonary thermodilution (PiCCO), or echocardiography to guide therapy in refractory shock. 1

Key Parameters to Monitor

• Pulmonary capillary wedge pressure (PCWP) 1
• Pulmonary artery pulsatility index (PAPI) 1
• Cardiac power output 1
• Cardiac index (CI) 1

Critical caveat: PCWP may not accurately reflect left ventricular end-diastolic pressure in certain conditions, and pressure estimates are generally insensitive indicators of volume status. 1

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Pediatric-Specific Considerations

Follow ACCM-PALS guidelines for pediatric septic shock management. 4

Resuscitation Endpoints in Children

• Capillary refill <2 seconds 4
• Normal blood pressure for age 4
• Normal pulses with no differential between peripheral and central 4
• Warm extremities 4
• Urine output >1 mL/kg/hr 4
• Normal mental status 4

Inotrope Selection in Pediatrics

• Individualized titration with epinephrine, levosimendan, dopamine, or dobutamine based on hemodynamic phenotype. 3
• Use dopamine cautiously at doses >7 mcg/kg/min as it may increase pulmonary vascular resistance. 3
• Begin peripheral inotropic support until central venous access is obtained in fluid-refractory patients 4

ECMO Considerations

• Consider ECMO early for refractory cardiogenic shock in pediatric myocarditis unresponsive to pharmacological therapy. 3
• Pre-cardiac arrest ECMO use may be beneficial in acute fulminant myocarditis 3

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Common Pitfalls to Avoid

• Do not rely solely on blood pressure for assessment; always evaluate tissue perfusion markers (lactate, mental status, urine output, capillary refill). 3, 1
• Do not delay echocardiographic evaluation in suspected cardiogenic shock. 3
• Do not continue aggressive fluid resuscitation if hepatomegaly or rales develop; switch to inotropic support. 4
• Do not use dopamine as first-line vasopressor in septic shock due to increased arrhythmia risk compared to norepinephrine. 4, 1

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Refractory Shock Management

Rule out and correct reversible causes: pericardial effusion, pneumothorax, intra-abdominal hypertension, and endocrine emergencies. 1

• Initiate continuous renal replacement therapy if fluid overload exceeds 10% despite diuretics 1
• Reassess shock phenotype and consider mechanical circulatory support for cardiogenic shock 1
• Verify adequate source control in septic shock 4