Question 10

An ICU patient is suitable for consideration of donation after circulatory determination of death (DCDD).

a) Outline the process of determination of death in these patients. (30% marks)

b) Define the term ‘functional warm ischaemic time’ and discuss its significance to subsequent graft function. (40% marks)

c) Compare and contrast graft survival rates in recipients of kidney, liver, heart, and lung transplantation from DCDD and from donation after neurological determination of death. (30% marks)

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College answer

This area of clinical practice is learned in mandatory CICM curriculum workshops, and therefore understanding of the process for determination of death in DCD patients should be well understood. The definition of functional warm ischemia time was incorrectly defined by most candidates, and knowledge of graft survival between different organs was also commonly incorrect.

Discussion

The exam candidate, task-focused and stressed, will probably ignore the fact that this question would have worked just as well without the one-line clinical scenario posed in the stem. "An ICU patient is suitable for consideration of donation after circulatory determination of death (DCDD)" even omits "organ" from "donation", which is even more curious. Were we expected to hang our answer off this slender twig? Hard to say. What follows has not made any attempt to address any clinical scenario. Fortunately everything needed to answer this question is easily available from the ANZICS statement.

a) The process of determination of death:

The determination of death requires the patient to be:

  • Unresponsive
  • Not breathing
  • Not moving
  • Has no pulse (by arterial monitoring, if possible, rather than ECG, though electrical asystole is also acceptable)
  • For 5 minutes.
  • After 5 minutes, absence of pulse and heart sounds is confirmed by clinical examination.

After this point, death should be documented using a specific form.

b) Functional warm ischaemic time:

"The functional warm ischaemic time is the time from when the systolic blood pressure falls below 50 mmHg after withdrawal of cardiorespiratory support to cold perfusion and may be a better measure of ischaemic injury" (according to the latest ANZICS statement)

The effect of this time is to delay the recovery of graft function, or make donation impossible if the specific time for each organ is exceeded:

  • Kidney: 60 minutes (from when systolic drops to lower than 50 mmHg)
  • Liver: 30 minutes (from withdrawal of cardiorespiratory support to cold perfusion)
  • Heart: 30 minutes (from when systolic drops to lower than 90 mmHg)
  • Lung: 90 minutes (from when systolic drops to lower than 50 mmHg)
  • Pancreas: 30 minutes (from withdrawal of cardiorespiratory support to cold perfusion)

c) Graft survival: DCDD vs DNDD:

  • Kidney:
    • Equal survival rates for recipients (86% at 5 years), whether they get kidneys from a DCDD or a DNDD donor
    • Delayed graft function is more common in the DCDD group, as the graft may be slightly more injured.
  • Liver:
    • DCDD recipient survival rates are lower (70-75% at 5 years)
    • Risks of ischaemic cholangiopathy are higher in DCDD 
  • Heart:
    • DCDD heart donation is not very well known; most donated hearts come from DNDD donors and graft survival in DCDD is not very well investigated
  • Lung:
    • DCDD graft survival rates approach 90% at 5 years and this is close to the results seen with DNDD grafts

References

ANZICS statement - the current version at the time of writing was 4.1 but you can always get the latest one from this ANZICS page