Obstructive shock

Obstructive shock is caused by mechanical compression of the heart, obstruction of the main vessels of the pulmonary or systemic circulation restricting or blocking blood flow. The result is decreased cardiac output and inadequate blood supply to the tissues.

It is less common than other types of shock (1-2% of shocks).

Causes of obstructive shock

• Pulmonary embolism (PE)
• Tension pneumothorax
• Cardiac tamponade
• Pulmonary hyperinflation (obstructive ventilatory disorders such as COPD, asthma,
• some aggressive ventilator settings)
• Hypertrophic cardiomyopathy (obstruction of the outflow tract by hypertrophic
• muscle)
• Aortic stenosis, aortic dissection
• Constrictive pericarditis
• Tumours, superior vena cava syndrome

Symptoms

The clinical picture is similar to that of patients with cardiogenic shock. However, differences
may be specific to the etiology of obstructive shock.

A: Depending on the level of consciousness, airway patency may be compromised. In severe cases of tension pneumothorax, tracheal deviation may occur.

B: Tachypnea, dyspnea, hyposaturation; diminished breath sounds in cases of pneumothorax, with possible subcutaneous emphysema; in pulmonary embolism, signs of pulmonary oedema, including hemoptysis, may be present.

C: Hypotension, tachycardia, thready pulse, peripheral cyanosis, cold clammy skin, mottling, prolonged capillary refill, oliguria progressing to anuria; increased jugular venous distension; in pulmonary embolism: signs of right-sided heart failure.

D: Altered consciousness: anxiety, confusion, and, in severe cases, quantitative disturbances of consciousness.

E: Chest pain (e.g., in pulmonary embolism, aortic dissection, or tension pneumothorax); asymmetric swelling of the lower extremities (deep vein thrombosis as a cause of pulmonary embolism).

Diagnostics

Clinical Examination:
The ABCDE approach, with concurrent application of the "treat-as-you-go" strategy.

Laboratory Tests:
Blood gas analysis and plasma lactate concentration, basic biochemical tests including troponin,
complete blood count and coagulation profile.

Imaging Modalities:
The choice of imaging depends primarily on the suspected cause and typically includes:

• Echocardiography (more commonly transthoracic echocardiography TTE)
  - evaluation of cardiac function (including diagnosis of signs of pulmonary embolism, cardiac tamponade, etc.).
• Chest X-ray - for tension pneumothorax
  - If tension pneumothorax is suspected based on clinical signs, chest puncture decompression can be performed immediately.
• Chest CT (Computed Tomography) incl. CT Pulmonary Angiography (CTPA): for pulmonary embolism and aortic dissection diagnosis.
  - Although it has the highest specificity and is used to confirm the diagnosis of PE definitively, its limitation is the need for patient transport; therefore, TTE is preferred in hemodynamically compromised patients.
• Ultrasound Examination 
  It is a reliable tool for detecting pericardial effusion in cardiac tamponade and can also be used to detect pneumothorax.
• ECG
  

Therapy

ABCDE Approach
incl. the application of the "treat-as-you-go" strategy.

Causal Therapy

• Tension Pneumothorax
  - Puncture decompression followed by chest drainage (refer to the Trauma and Polytrauma chapter for further details).
• Pulmonary Embolism
  - In cases of haemodynamic instability (i.e., high-risk pulmonary embolism), thrombolytic therapy is indicated (Note: Thrombolysis has many contraindications; consult a cardiologist before administration). Mechanical thrombectomy is another option.
  - anticoagulation therapy is the cornerstone of PE treatment (heparin or LMWH, followed by DOACs or warfarin); specific regimens and doses should be consulted with a cardiologist or haematologist.
• Cardiac Tamponade
  - Pericardiocentesis (should be performed by an experienced cardiologist or intensivist).
• Pulmonary embolus p. 376