SHOCK

Important points

• Unrecognised circulatory failure is the commonest cause of preventable death in the ED and hospitalised patients
• Hypotension is a LATE sign of shock
• Common scenarios of unappreciated shock are:
  • Septicaemic shock in infection
  • Occult bleeding from upper or lower gastrointestinal haemorrhage
  • Internal bleeding in thoraco-abdominal-pelvic trauma
  • Severe dehydration
• Consider early invasive monitoring e.g. urinary catheter, CVC
• Regardless of aetiology - the general approach to shock follows the same principles
• If in doubt - attempt an empirical fluid bolus and observe for a change in clinical signs

Clinical features

Hypotension is a LATE sign

(Hypotension occurs once all physiological mechanisms are exhausted = decompensated shock)

The initial signs may include one of the following:

• Tachycardia
• Cool peripheries/Diaphoresis
• Poor capillary return/Skin mottling
• Altered mental state
• Decreased urine output
• Low venous Bicarbonate
• Metabolic acidosis - Low pH/Bicarbonate (if you see a low bicarbonate think shock)

Resuscitation

Airway - protect if comatose

Breathing - high flow oxygen 15L/min by non-rebreather mask, controlled ventilation if inadequate respiratory effort or refractory hypoxaemia

CIRCULATORY MANAGEMENT

1. FLUIDS

Indications

• Any cause of shock (but give adrenaline early in anaphylaxis)
• Haemorrhagic shock generally needs fluids/blood only

Relative Contraindications

• Ruptured aortic aneurysm (needs urgent surgery)
• Penetrating truncal trauma (needs urgent surgery)

Procedure

• Large bore IV access - 16G X 2 (see IV cannula size and fluid flow rates)
• Replace what is lost - Crystalloid/Colloid in most cases, Blood in haemorrhagic shock
• Start with Normal Saline/Gelofusin/Haemacell 500-1000ml bolus over 5 min
• Use 250 ml bolus with history of heart failure, end stage renal failure, acute myocardial infarction, cardiogenic shock
• Monitor PR/BP/perfusion and signs of fluid overload - lung crepitations, alveolar oedema on CXR
• Repeat fluid bolus until there is an improvement in clinical signs or pulmonary oedema develops
• Insert IDC - measure hourly urine output - keep U/O > 0.5ml/kg/hr

2. PRESSOR SUPPORT

   Indications

• Co-existing pulmonary oedema
• Septicaemic shock not responding to fluids
• Spinal shock
• High spinal anaesthetic block

Procedure

• Administer IV metaraminol 1-2mg @ 3min
• Commence noradrenaline 1-10 mcg/min
• Titrate upwards until adequate BP and urine output
• Obtain early central venous access - aim for CVP ~ 12-15cmH2O

3. INOTROPIC SUPPORT

Indications

• Co-existing pulmonary oedema
• Anaphylactic shock
• Cardiogenic shock
• Septic shock not responding to above

Procedure

• Administer IV adrenaline 5-100mcg @ 3 min
• Commence adrenaline 1-10 mcg/min
• Titrate upwards until adequate BP and urine output
• Obtain early central venous access - aim for CVP ~ 12-15cmH2O

DEFINITIVE MANAGEMENT

TREAT CAUSE

• Haemorrhagic shock due to trauma - compress external wounds, splint fractures, stabilise pelvic fracture, urgent surgical treatment/angiographic intervention of internal bleeding
• Haemorrhagic shock due to upper GI bleeding - Sengstaken Blakemore tube, octreotide, urgent endoscopic/surgical intervention
• Haemorrhagic shock due to lower GI bleeding - Urgent surgical/angiographic intervention
• Haemorrhagic shock (Other causes) - Surgical intervention
• Septicaemic shock - Broad-Spectrum antibiotics +/- surgical treatment of abscess/collections/necrotic tissue
• Anaphylaxis - Adrenaline, Promethazine, Steroids
• Cardiogenic shock - Balloon pump, PTCA for acute MI, Valve replacement for acute valve lesions