Pathophysiology
Initial Stage – Compensatory mechanisms (tachycardia, vasoconstriction) maintain perfusion.
Progressive Stage – Oxygen delivery fails → Anaerobic metabolism → Lactic acidosis → Cell dysfunction.
Irreversible Stage – Multi-organ failure → Death if untreated.
Types of Shock
Hypovolemic Shock (Volume Loss):
Cause: Severe blood or fluid loss (e.g., hemorrhage, burns, diarrhea, vomiting).
Mechanism: Reduced preload (venous return) → ↓ Stroke volume → ↓ Cardiac output.
Cardiogenic Shock (Pump Failure):
Cause: Heart dysfunction (e.g., myocardial infarction, arrhythmias, myocarditis).
Mechanism: Inability of the heart to pump blood effectively → ↓ Cardiac output.
Distributive Shock (Vasodilation):
Septic Shock: Caused by severe infection and systemic inflammation.
Anaphylactic Shock: Allergic reaction causing massive histamine release and vasodilation.
Neurogenic Shock: Spinal cord or brain injury causing loss of vascular tone.
Mechanism: Peripheral vasodilation → ↓ Systemic vascular resistance → Inadequate perfusion.
Obstructive Shock (Blocked Circulation):
Cause: Physical obstruction (e.g., pulmonary embolism, cardiac tamponade, tension pneumothorax).
Mechanism: Impaired blood flow → ↓ Cardiac output.
Symptoms
General Symptoms:
Hypotension, tachycardia, cold/clammy skin (warm in distributive shock), altered mental status, oliguria, weak pulse, rapid breathing.
Specific Symptoms:
Hypovolemic: Dry mucous membranes, reduced skin turgor, flat neck veins.
Cardiogenic: Chest pain, lung crackles, distended neck veins.
Septic: Early fever/flushed skin, later cool/mottled skin.
Anaphylactic: Hives, angioedema, stridor, wheezing.
Neurogenic: Bradycardia, warm dry skin, paralysis below injury.
Diagnosis
Clinical Assessment: Vital signs, skin color, capillary refill.
Laboratory Tests:
Elevated lactate, metabolic acidosis (ABG).
CBC, electrolytes, renal function.
Imaging: Chest X-ray, CT, ultrasound for causes.
Hemodynamic Monitoring: CVP, pulmonary artery catheterization.
Treatment
General Management:
Airway: Secure airway, intubation if needed.
Breathing: Oxygen or ventilation.
Circulation: IV fluids, vasopressors.
Specific Treatments:
Hypovolemic: IV crystalloids, blood transfusion if hemorrhage.
Cardiogenic: Inotropes, diuretics, revascularization (PCI/CABG).
Septic: Antibiotics, IV fluids, vasopressors, corticosteroids if refractory.
Anaphylactic: IM epinephrine, antihistamines, corticosteroids, airway support.
Neurogenic: IV fluids, vasopressors, spinal stabilization.
Obstructive: Pericardiocentesis, chest tube, thrombolytics/embolectomy.
Prognosis and Complications
Prognosis: Depends on type, cause, and timely intervention. Early treatment improves outcomes.
Complications: Multi-organ dysfunction syndrome (MODS), ARDS, renal failure, death if untreated.