Makindo Medical Notes

Related Subjects: Atropine | Acute Anaphylaxis | Basic Life Support | Advanced Life Support | Adrenaline/Epinephrine | Acute Hypotension | Cardiogenic shock | Distributive Shock | Hypovolaemic or Haemorrhagic Shock | Obstructive Shock | Septic Shock and Sepsis | Shock (General Assessment) | Toxic Shock Syndrome | Non-Invasive Ventilation (NIV) | Intubation and Mechanical Ventilation | Critical Illness Neuromuscular Weakness | Multiple Organ Dysfunction Syndrome

Initial Shock Management: Oxygen 15 L/min unless COPD

Insert large-bore IV access. Send bloods. Administer oxygen. Get ECG and check Troponin levels. Assess fluid status. If the patient is hypovolemic, consider a fluid bolus. Send FBC, U&E, LFT, Group and Hold, +/- Lactate, Troponin, D-Dimer, ABG. Consider placing a urinary catheter to monitor urine output. If the patient has chest pain, perform an ECG and CXR. Assess for STEMI and determine if the patient is a candidate for PCI or thrombolysis. For arrhythmias: Tachycardia (consider DC shock); Bradycardia (Atropine/Pacing). Assess for valve, septal, or chordal failure and consider an urgent echocardiogram and surgical review. In some cases, Dobutamine and/or low-dose Dopamine may be required. An intra-aortic balloon pump may be indicated. Seek senior advice promptly.

In cases of acute coronary syndromes (ACS), interventions such as PCI, thrombolysis, or other strategies may be necessary. Prompt reperfusion of the coronary artery can rapidly restore myocardial function and improve survival.

Overview

• Cardiogenic shock is a medical emergency requiring rapid intervention and senior support.
• The primary issue in cardiogenic shock is inadequate cardiac output. Immediate investigation of the cause is crucial.
• Bedside echocardiography is invaluable for evaluating ventricular function, valve integrity, and excluding conditions like tamponade.
• If ST elevation or new LBBB is present, primary PCI is the preferred reperfusion strategy.

Introduction

• Shock is a clinical syndrome of organ hypoperfusion and is not a diagnosis by itself.
• Cardiogenic shock is specifically due to failure of the heart to pump blood effectively.
• Without prompt intervention, the condition will rapidly deteriorate due to a downward spiral of worsening shock and hypoperfusion.
• Always exclude conditions like RV infarction or tamponade, which require specific treatments such as fluid resuscitation or drainage.

Common Causes

• Myocardial Disease:
  • Ischaemic cardiomyopathy
  • Myocardial infarction (often anterior STEMI or NSTEMI)
  • Myocarditis
  • Cardiomyopathy
• Valve Failure:
  • Endocarditis
  • Acute mitral regurgitation (MR)
  • Acute ventricular septal defect (VSD)
  • Aortic regurgitation
• Toxins:
  • Verapamil overdose
  • Excess beta-blockers and other negative inotropes
• Congenital Heart Disease: Particularly in neonates and infants
• Arrhythmias:
  • Ventricular tachycardia
  • Fast atrial fibrillation
  • Heart block

Clinical Presentation

• Hypotension: BP < 90/60 mmHg, poor central pulse, cold extremities, altered mental status
• Atrial fibrillation (AF), dependent oedema, dyspnoea
• Raised JVP, which may increase with inspiration (Kussmaul’s sign)
• Third heart sound (S3), ascites, hepatomegaly, and ankle oedema
• Tension pneumothorax: Reduced breath sounds, resonant chest, tracheal deviation away from the affected side
• Tamponade: Raised JVP, faint heart sounds, globular heart silhouette on CXR, and small ECG complexes

Investigations

• FBC: Consider transfusion if Hb < 90 g/L. Administer diuretics slowly if necessary.
• U&E: Look for elevated creatinine and potassium, and raised lactate indicating hypoperfusion.
• LFTs: Raised AST indicates hepatic ischaemia.
• ECG: Check for low voltage, ST elevation, or new LBBB, and signs of posterior MI.
• Echocardiogram: Urgent to assess LV dysfunction and valve integrity. Consult cardiology.
• ABG: Assess for hypoxia and metabolic acidosis.
• CT/MRI: Useful for ruling out conditions such as constrictive pericarditis.

Management

• Mortality in cardiogenic shock is approximately 70% unless there is an easily treatable cause, such as large MI, which can be managed with PCI or revascularization.
• Administer oxygen (15 L/min via non-rebreather mask) unless the patient has COPD, in which case 28-35% oxygen is preferred. Reassess with ABG after stabilization.
• For chest pain and ST elevation, administer Diamorphine 2.5-5 mg slow IV or Morphine 2.5-5 mg slow IV, then follow STEMI protocols for Primary PCI or thrombolysis if PCI is unavailable.
• For arrhythmias (fast AF), if the patient is not on Digoxin, administer Digoxin 500 mcg slow IV or Amiodarone 300 mg over 1 hour. Use a large-bore or central line. If no improvement, consider synchronised DC cardioversion. Summon anaesthetic support for further intervention.
• If tamponade is suspected, perform an emergency echocardiogram and pericardiocentesis. Insert the needle to the left of the xiphisternum, aiming towards the left shoulder, and aspirate pericardial fluid while monitoring ECG. Defibrillation equipment should be ready.
• Consider placing a central line or Swan-Ganz catheter if experienced personnel are available. Use pulmonary wedge pressure to guide fluid management if under 15 mmHg, indicating the need for a fluid challenge.
• Insert a urinary catheter to monitor renal perfusion and guide fluid management.
• If hypovolaemia is suspected, administer a plasma expander (100 ml over 10-15 minutes), then reassess fluid status.
• For inotropic support, first-line treatment is adrenaline, which has both inotropic and vasoconstrictive effects. Monitor blood pressure via arterial line. Infuse adrenaline via a central line.
• Intra-aortic balloon pumping (IABP) may significantly improve cardiac output and is useful as a bridge to revascularization or valve repair. However, it is contraindicated in acute aortic regurgitation. The balloon pump inflates during diastole and deflates during systole, enhancing coronary and cerebral perfusion.

Drug Actions

Drug	Vasoconstriction	Inotrope	Heart Rate	Vasodilation
Low Dose Dopamine	0	++	++	++
High Dose Dopamine	+++	++	++	++
Low Dose Dobutamine	0	++++	+	++
High Dose Dobutamine	++	++++	+	++
Noradrenaline	++++	++	0	0
Adrenaline	++++	++++	++++	+++