Shock

Shock is a life-threatening condition. The effects of shock are initially reversible, but rapidly become irreversible, resulting in multiple organ failure and death.

Causes

There are 4 classes of shock. Patients will often have a combination of these.

• Cardiogenic: myocardial infarction, atrial and ventricular arrhythmias, valve or ventricle septal rupture shock.
• Distributive: septic, systemic inflammatory response syndrome, neurogenic, anaphylactic, toxic, end-stage liver disease and endocrine shock.
• Hypovolaemic: haemorrhagic and non-haemorrhagic fluid losses shock.
• Obstructive: pulmonary embolism, pulmonary hypertension, tension pneumothorax, constrictive pericarditis and restrictive cardiomyopathy shock.

Assessment

History and examination

Prioritise patients according to severity of shock and need for immediate interventions.

Brief history and rapid A-G assessment to determine shock severity and manage undifferentiated hypotension or shock.

General assessment

Include a thorough history and assessment of sensorium, mucous membranes, lips and tongue, neck veins, lungs, heart, abdomen, skin and joints.

Hypotension; oliguria; changes in mental status; and cool, clammy skin are sentinel clinical findings that should raise the suspicion of shock and prompt immediate treatment with IV fluids and further evaluation with laboratory studies and relevant imaging.

The clinical findings associated with undifferentiated shock vary according to the aetiology and stage of presentation (pre-shock, shock, end-organ dysfunction). Symptoms highly suspicious of shock include:

• abnormal mental status
• cool, clammy, cyanotic skin
• hyperlactatemia
• hypotension
• metabolic acidosis
• oliguria
• tachycardia
• tachypnoea.

Suggested investigations, as indicated

• Blood gas analysis
• Cardiac enzymes and natriuretic peptides
• Coagulation studies and D-dimer level
• Complete metabolic panel, including renal and liver function tests
• Complete blood count and differential
• ECG
• Imaging and/or ultrasound
• Serum lactate

Management

When a patient presents with undifferentiated shock, immediately initiate therapy while rapidly identifying the aetiology so that definitive therapy can be administered to reverse the shock and prevent multiple organ failure and death.

For patients with undifferentiated hypotension or shock, use a multidisciplinary, team-based approach, where feasible. This allows the simultaneous evaluation and administration of therapy to patients with hypotension and shock.

Treatment is dependent upon rapid A-G assessment and brief history.

This is a guide only. Complete steps simultaneously as able. Clinical discretion is advised.

• Manage airway, breathing, circulation, level of consciousness, exposure and glucose.
• Give fluid resuscitation (crystalloid, colloid, blood products). Assess volume deficit.
• Complete early investigations to determine type of shock. Treat aetiology, escalate and consult with relevant specialty for timely advice and/or access to definitive treatment.
• Correct electrolyte and acid-base disturbances.
• Give medications, such as antibiotics, vasopressors or inotropes, as indicated.
• Monitor and reassess patient response to treatment frequently.

Specific guidance

Refer to the ECAT protocols, clinical tools and other resources on the Unstable or critically ill patients page for guidance on specific conditions.

Background

Shock is best defined as a state of reduced end-organ oxygenation caused by an imbalance between tissue oxygen delivery and demand resulting in an oxygen debt. It most commonly presents with hypotension and elevated serum lactate levels.

Whatever the aetiology, shock is characterised by release of cytokines and other inflammatory mediators that cause a systemic inflammatory response syndrome mediated by tissue hypoxia. This causes alterations in flow at the level of the microcirculation that can usually be reversed by intravascular volume resuscitation and, as appropriate, vasopressor and inotropic support.

Resources

• Assessment of shock (NSW Health login required)
  Summary of the basic pathophysiology, outcomes and differentials for assessment of shock.
  Source: BMJ Best Practice
• Definition, classification, etiology, and pathophysiology of shock in adults (NSW Health login required)
  Detailed, evidence-reviewed analysis of shock.
  Source: UpToDate
• Evaluation of and initial approach to the adult patient with undifferentiated hypotension and shock (NSW Health login required)
  Detailed, evidence-reviewed point-of-care process for assessment and treatment of shock.
  Source: UpToDate
• Evaluation and management of suspected sepsis and septic shock in adults (NSW Health login required)
  Detailed, evidence-reviewed point-of-care process for assessment and treatment of people with sepsis and septic shock.
  Source: UpToDate
• Treatment of severe hypovolemia or hypovolemic shock in adults (NSW Health login required)
  Detailed, evidence-reviewed point-of-care process for assessment and treatment of people with hypovolemia or hypovolemic shock.
  Source: UpToDate