Question 2

Created on Thu, 08/31/2017 - 23:23
Last updated on Thu, 12/07/2017 - 03:39
Pass rate: 44.9%
Highest mark: 7.7

Other SAQs in this paper

Other SAQs on this topic

A 37-year-old male has been admitted to your ICU following an explosion in his garage. He has suffered a mixture of partial and deep burns estimated at 35% total body surface area, and has been intubated in the Emergency Department. After one hour of resuscitation in your unit he remains hypotensive with a blood pressure of 80/50 mmHg.

List the potential causes and outline how you would diagnose and manage them.

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College answer

1. Spurious

  1. Damped or poorly functioning, zeroed, arterial line
  2. Inappropriate sized cuff
    1. Check line, cuff size
    2. Measure second site, alternative modality

2. Hypovolemia

  1. Review volumes of administered fluids to date
  2. Confirm size and depth of burn
  3. Check calculations for fluid resuscitation are correct
  4. Rising haematocrit, ECHO findings

i. Increase fluid resuscitation rate

3. Bleeding from occult/missed injury

a. Review/repeat trauma imaging

i. Blood product resuscitation, correction of coagulopathy ii. Operative/Interventional radiology interventions to treat cause

  1. Sepsis             
    1. Too early for burn sepsis – possible intraabdominal or thoracic blast injury
      1. Broad spectrum antibiotics and source control
  2. Distributive
    1. High cervical spine injury
      1. Review imaging, vasopressors
    2. Anaphylaxis to drugs
      1. Review history, examine for rash/bronchospasm, adrenaline c. Cyanide toxicity

i. Mixed venous oxygen, empirical antidote administration

Cardiogenic

    1. Takustubo, underlying cardiac disease, blast injury, myocardial toxins
      1. ECHO, ECG, Inotropic support
  1. Obstructive
    1. Tension pneumothorax
      1. CXR, drainage

b. Abdominal compartment syndrome

i. Bladder pressure, escharotomies, laparotomy/laparostomy

c. Tamponade

i. Echo and pericardiocentesis

Examiners comments: 

 Most candidates were not able to amalgamate the three crucial aspects of this patient i.e., trauma in a burns patient in the setting of a closed area explosion.

 Many focused solely on the burns with little reference to the trauma. 

 Many used a generic ABCD template without applying it to the patient.

 Many answer structures were haphazard with an initial list of the causes followed by the management, with the result that the management for a number of the differentials were missed.

 The best answers used a table or bulleted list approach taking about causes as well as management.

Discussion

Though the college describes this as an "explosion", it is highly unlikely that this patient was exposed to a blast wave (as usually household explosions are of the deflagration variety) and so the discussion will focus mainly on the investigations and management of burns-related hypotension. Blast injury is mentioned in the list as an aside, in response to the comment that most answers "focused solely on the burns with little reference to the trauma".

Thus:

Possible causes of shock in this patient (table adapted from "Causes of Shock in the Trauma Patient")

Type of shock Cause Diagnostic strategy
Artifact of measurement Blood pressure measurement is inaccurate
  • Check pulse
  • Check for disagreement between measurement modalities (eg. art line and NIBP)
Cardiogenic Cardiac contusion (blast)
  • S3
  • Pericardial rub
  • Anterior ST changes
Myocardial infarction
  • ECG changes
  • cardiac enzyme elevation
Arrhythmia
  • Irregular pulse, bradycardia or tachycardia
  • ECG
Obstructive Cardiac tamponade
  • Raised JVP, CVP
  • Pulsus paradoxus
  • JVP rises on inspiration (Kussmaul's sign)
  • Muffled heart sounds
Tension pneumothorax
  • Surgical emphysema
  • Tracheal deviation away from side of pneumothorax
  • Quiet breath sounds on side of side of pneumothorax
Fat embolism (blast)
  • Confusion
  • Petechial rash over face, axillae, root of neck
  • Hypoxia
Neurogenic Spinal injury
  • hypotension without compensatory tachycardia
  • warm extremities
  • paralysis
Hypovolemic Massive blood loss
  • Jugular venous pressure not visible
  • Positive response to passive leg raise
  Massive fluid shift
  • As above (i.e. dynamic predictors suggest fluid responsiveness)
Distributive Anaphylaxis (induction drugs)
  • angioedema
  • urticaria
  • facial swelling
  • wheeze

Management, therefore, will consist of the following steps:

  • Confirm blood pressure measurement invasively (i.e. insert an art line)
  • Exclude immediately lifethreatening causes of shock:
    • Tension pneumothorax (examination)
    • Cardiac tamponade (TTE)
  • Estimate fluid requirements using the modified Parklands Formula
  • Assess fluid responsiveness via multimodal approach (combination of dynamic and static tests, including physical examination, ABG lactate, pulse pressure variation and passive leg raise)
  • Offer a combination of crystalloid and colloid (expecting protein losses to be substantial)
  • Vasopressors may be required (a vasodilated state formerly known as SIRS may develop)

References

Moore, Francis D., et al. "The role of exudate losses in the protein and electrolyte imbalance of burned patients." Annals of surgery 132.1 (1950): 1.

Latenser, Barbara A. "Critical care of the burn patient: the first 48 hours." Critical care medicine37.10 (2009): 2819-2826.

Asch, MORRIS J., et al. "Systemic and pulmonary hemodynamic changes accompanying thermal injury." Annals of surgery 178.2 (1973): 218.

Crum, Ralph L., et al. "Cardiovascular and neurohumoral responses following burn injury."Archives of Surgery 125.8 (1990): 1065-1069.