Rosen & Barkin's 5-Minute Emergency Medicine Consult (130 page)

• AMI
  
• Sepsis
  
• Myocarditis
  
• Myocardial contusion
  
• Valvular disease
  
• Cardiomyopathy
  
• Left atrial myxoma
  
• Drug toxicity:
  
  • β-blocker
    
  • Calcium channel blocker
    
  • Adriamycin
    

DIAGNOSIS

• ABCs and vital signs:
  
  • Patent airway (early)
    
  • Labored breathing and tachypnea (early); respiratory failure (late)
    
  • Diffuse crackles or wheezing
    
  • Hypoxia
    
  • Hypotension:
    
    • Systolic BP <90 mm Hg
      
    • Decline by at least 30 mm Hg below baseline level
      
  • Tachycardia
    
  • Weak pulses
    
• General:
  
  • Cyanosis
    
  • Pallor
    
  • Diaphoresis
    
  • Dulled sensorium
    
  • Decrease in body temperature
    
  • Urine flow of <20 mL/hr
    
• Neck:
  
  • Jugular venous distention
    
• Cardiac:
  
  • Ischemic chest pain
    
  • Systolic apical blowing murmur
    
  • Gallop rhythm:
    
    • S3 reflects severe myocardial dysfunction.
      
    • S4 is present in 80% patients in sinus rhythm with AMI.
      
  • Systolic click:
    
    • Suggests rupture of the chordae tendineae
      
• Abdominal:
  
  • Epigastric pain
    
  • Nausea and vomiting
    
• Neurologic:
  
  • Obtundation
    

• Obtain history from patient, family, or EMS for clues to possible etiology
  
• Medications history
  

• Perform rapid survey and stabilize ABCs
  
• Distended neck veins and cool extremities distinguish cardiogenic shock from distributive and hypovolemic shock
  
• Careful heart and lung exam
  

Ancillary studies further define the type and degree of cardiac injury and determine the indications for emergent catheterization or surgical intervention.

ECG:

• Normal ECG does not rule out AMI.
  
• Findings of AMI (ST-elevations in 2 or more contiguous leads)
  
• May occur in non–ST-elevation acute coronary syndrome
  
• Dysrhythmias
  
• LV hypertrophy
  

• B-type natriuretic peptide (BNP):
  
  • Diagnostic and prognostic value
    
• Creatine kinase (CK), CK-MB, troponin
  
• Electrolytes and renal function:
  
  • Acute renal failure is a strong predictor of mortality.
    
• CBC:
  
  • Identify anemia or elevated WBC.
    
• Drug levels (e.g., digoxin)
  

• CXR:
  
  • Pulmonary congestion
    
  • Pleural effusion
    
  • Cardiomegaly
    
  • Pneumonia
    
  • Pneumothorax
    
  • Pericardial effusion
    
• Emergent echocardiography:
  
  • Transthoracic echocardiography (TTE) with color Doppler
    
  • LV contractility looking for hypokinesis, akinesis, or dyskinesis
    
  • Acute mitral regurgitation or septal defects
    
  • RV dilatation, tricuspid insufficiency, high pulmonary artery and RV pressures suggest pulmonary embolism
    
  • RV hypokinesis or akinesis, RV dilatation, normal pulmonary pressures suggest RV infarction
    
  • Pericardial effusion, right atrium or RV diastolic collapse suggest cardiac tamponade
    

• Obstructive shock:
  
  • Tension pneumothorax
    
  • Cardiac tamponade
    
  • Pulmonary embolism
    
  • Spontaneous esophageal rupture
    
  • Air embolus
    
• Distributive shock:
  
  • Sepsis
    
  • Anaphylaxis
    
  • Addisonian crisis
    
  • Neurogenic shock
    
• Hypovolemic shock:
  
  • Hemorrhage
    
  • GI losses
    
  • Dehydration
    
  • Burns
    

TREATMENT

• ABCs, IV access, O
  ₂
  , monitor
  
• Consider fluid bolus if no crackles
  
• Aspirin
  
• Nitroglycerin or morphine sulfate for chest pain in absence of hypotension
  
• Transport AMI patients to facility with 24-hr cardiac revascularization capability
  

• ABCs
  
• 2 large-bore peripheral IV lines
  
• Cardiac monitor
  
• Endotracheal intubation for airway compromise:
  
  • Consider etomidate for induction (minimal effect on BP)
    
• Fluid challenge (100–250 mL normal saline) in absence of pulmonary congestion
  
• Foley catheter to monitor urine output
  

• AMI:
  
  • Aspirin
    
  • Heparin
    
  • Thrombolysis if percutaneous coronary intervention or bypass surgery not available
    
  • GP IIb/IIIa inhibitors prior to percutaneous coronary intervention
    
• Hypotension:
  
  • Norepinephrine is 1st-line vasopressor
    
  • Consider dopamine in absence of NE
    
• Normotensive patient:
  
  • Dobutamine may be used with NE or dopamine; combine with nitroprusside in acute mitral regurgitation
    
  • Milrinone may be considered in conjunction with dobutamine or dopamine
    
• Pulmonary edema:
  
  • Nitroglycerin drip or furosemide in the normotensive patient
    
• Prompt cardiology consultation is crucial for the initiation of the following therapies:
  
  • IABP independently improves survival in experienced centers
    
  • Early revascularization is the single most important life-saving measure
    

• Dobutamine: 3–5 μg/kg/min, titrate to 20–50 μg/kg/min as needed IV
  
• Dopamine: 3–5 μg/kg/min, titrate to 20–50 μg/kg/min as needed IV
  
• Furosemide: 40–80 mg/d (peds: 1 mg/kg IV or IM, not to exceed 6 mg/kg) IV or IM
  
• Milrinone: 50 μg/kg loading dose, 0.375–0.75 μg/kg/min continuous infusion IV
  
• Nitroglycerin: 10–20 μg/min (peds: 0.1–1 μg/kg/min) IV, USE NON-PVC tubing
  
• Nitroprusside: 0.3 μg/kg/min, titrate to a max. of 10 μg/kg/min IV
  
• Norepinephrine: 2 μg/min, titrate up as needed IV
  

FOLLOW-UP

All patients in cardiogenic shock require admission to a critical care unit.

• Cardiogenic shock is the leading cause of death in inpatient AMI.
  
• Early recognition of preshock states is essential.
  
• Early revascularization offers better outcomes.
  

• De Backer D, Biston P, Devriendt J, et al. Comparison of dopamine and norepinephrine in the treatment of shock.
  N Engl J Med.
  2010;362:779–789.
  
• Peacock WF, Weber JE. Cardiogenic shock. In: Tinitinalli JE, Stapczynski JS, eds.
  Emergency Medicine: A Comprehensive Study Guide
  . New York, NY: McGraw-Hill; 2010.
  
• Reynolds HR, Hochman JS. Cardiogenic shock: Current concepts and improving outcomes.
  Circulation.
  2008;117:686–697.
  
• Topalian S, Ginsberg F, Parrillo JE. Cardiogenic shock.
  Crit Care Med.
  2008;36:S66–S74.
  

See Also (Topic, Algorithm, Electronic Media Element)

Shock; MI

CODES

785.51 Cardiogenic shock