Question 3

A 56-year-old male was trapped for a prolonged period from the waist down between his slow rolling 4- wheel drive car and a brick wall. On presentation, he has a heart rate of 150 beats/minute and a systolic blood pressure of 80 mmHg. He has obvious bruising extending from his lower abdomen to just above his knees. There is blood at his penile meatus.
a)    List the likely injuries (3 marks)
b)    Outline your blood product and fluid administration over the first 24 hours (4 marks)

c)    List the complications you would anticipate in this patient during the first 72 hours (3 marks)


 
 


 

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College comments

Syllabus topic/section: 2.1.13 Trauma Intensive Care

Discussion: 

Candidates who scored well in part a) provided a structured list of injuries relevant to the case. Conversely answers that lacked structure tended to miss relevant injuries and this then correlated with missing complications in part c). The above standard answer concentrated on injuries relevant to the stem, including pelvic, complex lower limb (including vascular) injuries and crush injuries including rhabdomyolysis.

Blood transfusion management in part b) was generally well answered. Many candidates did not put equal emphasis on fluid administration, which was equally important, given the significant risk of crush injury and associated rhabdomyolysis. Both Blood AND fluid management was asked for in the stem. Easy marks were lost due to not following the question directions.

Given the history provided, complications secondary to crush injury with rhabdomyolysis and vascular injury were required for an at standard answer. A broad range of complications in part c) was required and better answers included those of therapy (eg MTP) as well as complications from the different injuries sustained. Examples of complications likely for this patient within the first 72 hours include AKI from both traumatic mechanisms and therapy, complications secondary to potential haemorrhagic shock and subsequent massive transfusion, complications of long bone fractures including fat embolism, compartment syndrome and ischemia from threatened vascular supply to the lower limbs.
 

Interpretation

a)    List the likely injuries (3 marks)

The stem presents us with a clearly crushed person. The clues in the stem include:

  • "for a prolonged period" suggests a crush injury, and indirectly suggests a sustained period of poor blood flow or uncontrolled haemorrhage
  • "from the waist down" suggests mostly lower limb and pelvic trauma
  • "slow rolling 4- wheel drive car" gives an approximate height for the crush direction (i.e. for a sedan one would be looking at knees and ankles instead)
  • "a brick wall" suggests a rough surface and abrasions
  • The vital signs suggest uncontrolled shock
  • "obvious bruising extending from his lower abdomen to just above his knees" suggests haemorrhage as the cause of the shock
  • "blood at his penile meatus" suggests urethral or bladder injury,  as well as pelvic fractures

This "list" question is weighed three marks, which suggests that something more than just "crush injuiry, rhabdo, pelvic fractures" was expected. A general rule is that a "list" like this scores more marks if it is ordered and categorised. For example:

  • List of injuries:
    • Bony injuries
      • Pelvic fractures
      • Femoral fractures
      • Sacroiliac joint fracture/dislocation
    • Muscle injuries
      • Crush injuries to thigh and pelvic musles
      • Interruption of lower limb blood supply
      • Rhabdomyolysis secondary thereto
    • Organ injuries
      • Bladder injury, urethral or ureteric injury
      • Sigmoid colon and rectum could also be affected by  sharp edges of pelvic fractures
      • Genital injuries are also plausible
      • Secondary AKI from rhabdomyolysis
    • Nerve injuries
      • Femoral nerve
      • Sciatic nerve
      • Sacral plexus
    • Vessel injuries
      • Femoral artery dissection/transection
      • Femoral venous thrombosis due to stasis
      • Pelvic venous plexus bleeding
    • Systemic consequences
      • Reperfusion-associated systemic inflammatory response
      • Electrolyte derangement due to reperfusion and rhabdomyolysis

This is 97 words, i.e. something representative of a 5-mark answer. Systemic consequences were not asked for and would probably not have scored many marks, but then the college commentary lists rhabdomyolysis as an injury, which one might argue it is not (one could characterise it as a post-injury systemic syndrome resulting from muscle necrosis)


b)    Outline your blood product and fluid administration over the first 24 hours (4 marks)

Blood and fluid were asked for. The abundant mark allocation suggests that the examiners expected a considerable amount of detail, and that the management steps could afford to be very specific. Thus:

  • Overall endpoints:
    • Prior to haemostasis:  SBP ~90 (permissive hypotension)
    • Post haemostasis:  MAP > 65, urine output of 1-3ml/kg/hr (AAST guideline, 2022)
  • Blood product administration
    • Severe shock (shock index, HR/SBP = 150/80 = 1.875)  suggests the need for massive transfusion 
    • 1:1:1 ratio of red cells, clotting factors and platelets - warmed during infusion
    • Fibrinogen replacement as factor concentrate or cryoprecipitate
    • correction of ionised hypocalcemia, acidosis, hypothermia - to reduce blood product use
    • Ongoing transfusion to be guided by TEG and coags
  • Fluid administration
    • Prior to haemostasis, prioritise blood products
    • Balanced crystalloids after haemostasis; rate of 400ml/hr, up to 1L/hr, titrated to target urine output
    • Total fluid dose in the first 24 hrs needs to balance the risk of increasing tissue oedema and worsening compartment syndrome
    • Isotonic or concentrated bicarbonate can be considered to alkalinise the urine, but the evidence for this strategy is weak 

Mutschler et al, 2013, observed that patients at this end of the spectrum required about 10 u PRBCs on average.

c)    List the complications you would anticipate in this patient during the first 72 hours (3 marks)

Again, a list with lots of marks attached suggests a need for more than just a basic unordered pile. Ordering this by systems may have value.

  • A: the need to remain intubated for repeated interventions
  • B: ARDS due to systemic inflammatory response/reperfusion and TRALI
  • C: Vasodilated shock state +/- ongoing intravascular volume depletion due to blood loss and compartment shifts; compartment syndrome of the lower limbs requiring fasciotomy; vascular injuries requiring stents , embolectomy or bypass 
  • D: significant analgesic requirements
  • E: hyperkalemia, hyperphosphatemia, hypocalcemia, metabolic acidosis
  • F: AKI with potential need for RRT; haematuria following bladder/urethral repair; suprapubic catheterisation; urine leak and urinoma
  • G: Interruption of GI tract following repair of any sigmoid/rectal injury, and/or ileus; pelvic haematoma 
  • H: consequences of massive transfusion, including TRALI
  • I: fevers resulting from peritoneal contamination and/or SIRS