What are the signs and symptoms of shock?

Signs and Symptoms of Shock

Shock is characterized by hypotension (systolic blood pressure <90 mmHg for >30 minutes) and signs of end-organ hypoperfusion, including altered mental status, cold extremities, decreased urine output, metabolic acidosis, and elevated lactate levels. 1

Core Clinical Features of Shock

Hemodynamic Signs

• Hypotension:
  • Systolic blood pressure <90 mmHg for >30 minutes 1
  • Mean arterial pressure <60 mmHg for >30 minutes 1
  • Requirement for vasopressors to maintain adequate blood pressure 1

Signs of Hypoperfusion

• Neurological manifestations:

  • Altered mental status/consciousness 1
  • Confusion, lethargy, irritability 1
  • Decreased responsiveness 1

• Skin changes:

  • Cold, clammy extremities 1
  • Peripheral vasoconstriction 1
  • Livedo reticularis (mottled skin) 1
  • Increased capillary refill time (≥3 seconds) 1
  • Temperature gradient (cool peripheries) 1

• Renal manifestations:

  • Oliguria (urine output <30 mL/hour or <0.5 mL/kg/hour) 1
  • Anuria in severe cases 1

• Metabolic derangements:

  • Elevated serum lactate (>2 mmol/L) 1
  • Metabolic acidosis 1
  • Decreased mixed venous oxygen saturation (SvO₂ <65%) 1

• Cardiac manifestations:

  • Tachycardia 1
  • Cardiac index <2.2 L/min/m² 1

Type-Specific Features

Cardiogenic Shock

• Pulmonary congestion/edema 1
• Elevated jugular venous pressure 1
• S3 gallop
• Pulmonary capillary wedge pressure >15 mmHg 1

Hypovolemic Shock

• Flat neck veins
• Dry mucous membranes
• Decreased skin turgor
• History of fluid loss (hemorrhage, vomiting, diarrhea)

Distributive Shock

• Warm, flushed skin (early septic shock)
• Fever or hypothermia (in septic shock)
• Widened pulse pressure (early)

Obstructive Shock

• Distended neck veins (in tension pneumothorax, cardiac tamponade)
• Pulsus paradoxus (in cardiac tamponade)
• Unilateral decreased breath sounds (in tension pneumothorax)

Pediatric Considerations

Children may present differently than adults with shock 1:

• Tachycardia is often the earliest sign
• Hypotension is a late and ominous sign
• Age-specific vital sign parameters must be used
• Symptoms such as malaise, lethargy, weakness, and reduced appetite may not be self-reported by younger children 1

Severity Classification

The Society for Cardiovascular Angiography and Intervention (SCAI) classification system for cardiogenic shock 1:

• Stage A: At risk (not in shock but at risk)
• Stage B: Beginning shock (hypotension without hypoperfusion)
• Stage C: Classic shock (hypoperfusion requiring intervention)
• Stage D: Deteriorating shock (not responding to initial interventions)
• Stage E: Extremis (cardiac arrest with ongoing CPR/ECMO)

Diagnostic Approach

Early recognition is critical for survival. When shock is suspected:

1. Obtain vital signs including blood pressure, heart rate, respiratory rate, temperature, and oxygen saturation

2. Assess mental status and urine output

3. Check capillary refill time and skin temperature

4. Obtain laboratory tests:

   • Serum lactate
   • Arterial blood gases
   • Complete blood count
   • Basic metabolic panel
   • Liver function tests
   • Coagulation studies

5. Consider invasive monitoring with arterial line in unstable patients 1

Common Pitfalls in Shock Recognition

• Delayed recognition: Relying solely on hypotension can delay diagnosis, as compensatory mechanisms may maintain blood pressure despite significant hypoperfusion
• Missing relative hypotension: Failure to consider the patient's baseline blood pressure can lead to missed diagnosis in chronically hypertensive patients 1
• Overlooking non-specific symptoms: Particularly in children and elderly patients, shock may present with subtle changes in mental status before overt hemodynamic compromise 1
• Attributing symptoms to other causes: Tachycardia may be misattributed to pain, anxiety, or fever rather than recognized as an early sign of shock 1

Early recognition and prompt intervention are essential to prevent progression to irreversible shock and death. The presence of hypotension with signs of end-organ hypoperfusion should trigger immediate resuscitative measures and diagnostic workup to identify and treat the underlying cause.