A 55 year old man has been admitted to your unit with 60% burns involving his face, chest, upper and lower limbs and torso. He has had some debridement and grafting of his burn sites. Ten days after admission,  after return from theatre following a debridement, he is noted to be hypotensive  with a blood pressure of 85/50 mm Hg. Briefly outline the causes and the management of his hypotension.

[Click here to toggle visibility of the answers]

College Answer

Possible causes

Investigation

1)  Ongoing fluid shifts and
evaporative fluid losses from raw surfaces
2)  Ongoing SIRS
3)  Bacteremia from operative stimulation. Sepsis – burn site, line sepsis, nosocomial sepsis, deep seated muscle sepsis, high risk of fungal sepsis, endocarditis
4)  Bleeding - from surgical and burn sites,
5)  Anaphylactic reactions to drugs
6)  Pneumothorax

Less likely
7)  Incidental PE (in hospital for 10 days)
8)  Myocardial dysfunction
9)  GI bleed from stress ulcers
10) Adrenal insufficiency described with burns.

1)  Clinical assessment of fluid
balance 
2)  Assessment of filling pressures
3)  Septic screen  - to include burn biopsies
4)  Hb
5)  ECG, troponin, Echo
6)  Screen for anaphylaxis – mast cell tryptase
7)  CTPA

Treatment

1)  Depends on cause
2)  Fluid bolus +/- inotropes – usually norad
3)  Line change if indicated
4)  Broad spectrum Gram positive and gram negative cover if sepsis is deemed likely.
+/- fungal cover
5)  PRBC as required
6)  Targeted therapy for PE /anaphylaxis

Discussion

One can easily see through the thin veneer of this burns history the college gives us. This is really just a boring question about the differential causes of shock.

Thus:

  • Artifactual shock
    • Art line inappropriately zeroed
    • Wrong size NIBP cuff
  • Technical error
    • CVC is extravasating vasopressors
    • Vasopressor infusion was improperly prepared
  • Obstructive shock
    • Cardiac tamponade
    • Tension pneumothorax
    • Pulmonary embolism
  • Distributive shock
    • Septic shock - bacterial translocation from infected burns which have been disturbed
    • Anaphylactic shock - a reaction to antibiotics or anaesthetic agents
    • Propofol-related vasoplegia
  • Hypovolemic shock
    • Haemorrhage intraoperatively
    • Inadequate fluid resuscitation in theatre
  • Cardiogenic shock
    • Intraoperative MI
    • Cardiodepressant effect of drugs

An approach to investigation would thus consist of the following:

  • Examination of the cardiorespiratory system to exclude anahylaxis, cardiac tamponade, pneumothorax and obvious haemorrhage
  • ABG to assess the severity of the metabolic acidosis
  • FBC to look for haemorrhage
  • Mast cell tryptase
  • Septic screen
  • ECG to exclude perioperative MI
  • CXR to look for features of cardiac failure
  • TTE to exclude tamponade and to look for features of cardiac failure or right heart dilation
  • CTPA to exclude PE