Shock

Shock is defined as haemodynamic instability + evidence of tissue hypoperfusion e.g. cold peripheries, mottled skin, oliguria, raised lactate. First sign seen here is Tachycardia.

It's main complications include:

• Cardiovascular collapse

• Acute renal failure

• DIC

• Death

COLD SHOCK

Hypovolemic shock occurs when there's a low blood volume. The most common cause of this is blood loss. But, less common causes include diarrhoea + vomiting (esp. in children), burns, polyuria in DKA/DI. Presents with cold peripheries, prolonged CRT, rapid/weak/thready pulse, and mottled skin. Managed by raising the legs, and given adequate fluid resuscitation.

Cardiogenic shock occurs when there's failure of the heart to pump effectively (poor cardiac output). Common causes of this includes MI, tension pneumothorax, cardiac tamponade, arrhythmia, HF, PE. Presents with cold peripheries, prolonged CRT, raised JVP, weak/absent pulse, arrhythmia, and increased WOB (work of breathing). Managed by investigating and treating the underlying cause e.g. PCI for STEMI, pericardiocentesis for tamponade.

WARM SHOCK

Septic shock is where there's systemic vasodilation, which causes a drop in BP and organ hypoperfusion. This leads to tissues carrying out anaerobic respiration and releasing lactate as a result. This is why it's important to test for lactate levels in the blood as it will be > 4mmol/L here. Presents with warm peripheries, quick CRT, and signs of localised infection. Managed with fluid resuscitation, and Abx for the primary infection.

Anaphylactic shock occurs when there's a severe allergic reaction causing the release of histamine, which causes systemic vasodilation, and leads to a drop in BP and organ hypo-perfusion. Presents with warm peripheries, quick CRT, and signs of an allergy (urticarial rash, angioedema, wheeze, SOB, abdo pain). Managed by removing the source, and giving IM Adrenaline (1:1000).

Other less commonly seen types of shock includes:

• Neurogenic - Severe traumatic brain, Spinal cord injury

• Endocrine/Metabolic - Addisonian crisis, Myxedema crisis, Beriberi (Thiamine/B1 deficiency)