SHOCK. CARDIAC ARREST
Definition of Shock
Shock is a life-threatening clinical syndrome resulting from inadequate tissue perfusion and oxygen delivery, leading to cellular hypoxia, organ dysfunction, and if not reversed, death.
Classification of Shock
Stages of Shock
- Initial stage: Hypoperfusion begins at cellular level, no clinical signs yet.
- Compensated stage:
- ↑ Heart rate and systemic vasoconstriction.
- BP may still be maintained.
- Progressive stage:
- Decreased perfusion to vital organs.
- Lactic acidosis, oliguria, hypotension appear.
- Irreversible stage:
- Multiple organ failure.
- Shock becomes unresponsive to treatment.
Clinical Features of Shock
Early Signs:
- Tachycardia
- Cool, clammy skin
- Weak, thready pulse
- Pallor, sweating
Late Signs:
- Hypotension
- Confusion or unconsciousness
- Oliguria or anuria
- Cyanosis
Diagnosis of Shock
Vital signs: BP ↓, HR ↑, RR ↑
Central venous pressure (CVP): ↓ in hypovolemia, ↑ in cardiogenic
Lactate level: Elevated due to anaerobic metabolism
Blood gas: Metabolic acidosis
Imaging/tests: ECG, chest X-ray, echo, labs depending on cause
Treatment Principles (ABCDE approach)
A – Airway: Ensure patency.
B – Breathing: Provide oxygen (high flow O₂, intubation if needed).
C – Circulation:
- IV fluids (crystalloids for hypovolemic shock)
- Blood transfusion (if hemorrhage)
- Inotropes/vasopressors (e.g., dopamine, norepinephrine)
D – Disability: Assess consciousness (GCS), glucose levels.
E – Exposure: Find and control source (bleeding, infection, trauma).
Cardiac Arrest
Definition
Sudden cessation of cardiac mechanical activity, confirmed by absence of circulation signs (no pulse, no breathing, unconsciousness).
Common Causes
Cardiac: MI, arrhythmias (VT/VF), heart failure
Respiratory: Airway obstruction, respiratory arrest
Metabolic: Electrolyte disturbances (e.g., K⁺), acidosis
Other: Hypovolemia, hypothermia, trauma, toxins
Types of Cardiac Arrest Rhythms
Signs and Symptoms
Sudden collapse
Loss of consciousness
No pulse, no breathing
Dilated pupils
Cyanosis
No cardiac sounds
Diagnosis
Clinical: Unconscious, pulseless, apneic
Monitor/ECG: Confirm rhythm (asystole, VF, VT, PEA)
Basic Life Support (BLS)
- Check responsiveness and breathing
- Call for help, activate EMS
- Start CPR:
- 30 chest compressions + 2 rescue breaths (rate: 100–120/min)
- Use AED as soon as available
Advanced Cardiac Life Support (ACLS)
Airway: Secure (intubate if needed)
Breathing: 100% oxygen
Circulation:
- IV/IO access
- Administer epinephrine every 3–5 min
- Defibrillation for shockable rhythms (VT/VF)
Reversible Causes (Hs & Ts):
- Hs: Hypoxia, Hypovolemia, Hypo/hyperkalemia, Hypoglycemia, Hypothermia, Hydrogen ion (acidosis)
- Ts: Tamponade, Tension pneumothorax, Thrombosis (MI/PE), Toxins, Trauma
Post-Resuscitation Care
Maintain oxygenation
Monitor for arrhythmias
Treat underlying cause
Targeted temperature management (therapeutic hypothermia)
Prognosis
Depends on:
- Duration before CPR started
- Initial rhythm (VF better than asystole)
- Return of spontaneous circulation (ROSC) time