Cardiogenic shock (acute heart failure)

This has a 90% mortality. Cardiogenic shock is shock caused primarily by the failure of the heart to maintain the circulation. It may occur suddenly, or after progressively worsening heart failure.

Causes:

Rapidly reversible:

• Arrhythmias
• Cardiac tamponade
• Tension pneumothorax

Others:

• MI
• Myocardial depression (drugs, sepsis, hypoxia, acidosis)
• Valve destruction (e.g. endocarditis)
• PE
• Aortic dissection

Management:

• Give O₂, with the patient placed in the most comfortable position
• Give diamorphine 2.5-5mg IV for pain and anxiety
• Monitor:
• ECG
• Urine output
• Blood gases
• U&Es
• CVP
• Perform a 12-lead ECG every hour until the diagnosis is made
• Correct:
• Arrhythmias
• U&E imbalances
• Acid-base balance
• Give positive inotropes (e.g. dobutamine2.5-10μg/hk/min IVI) adjusted to keep systolic BP >80mmHg
• Increase renal perfusion by low-dose dopamine (2-5μg/kg/min IVI)
• Look for and treat any reversible cause (e.g. PE, MI) – consider thrombolysis

Cardiac tamponade:

• Pericardial fluid accumulates, intra-pericardial pressure rises, the heart cannot fill and pumping stops

Major causes:

• Trauma
• Lung/breast cancer
• Pericarditis
• MI
• Bacteria (e.g. TB)

Signs of a cardiac tamponade:

Beck’s triad:

• Falling BP
• Rising JVP
• Muffled heart sounds

Echocardiography may be diagnostic

CXR will show:

• Globular heart
• Left heart border convex or straight
• Right cardiophrenic angle <90˚