Diagnosing death

Question 1

What is death?

Answer 1

The irreversible loss of the capacity for consciousness, combined with the irreversible loss of capacity to breathe.

Question 2

How is death diagnosed?

Answer 2

Death can be diagnosed by somatic criteria, circulatory criteria or neurological criteria.

Question 3

What are the preconditions for brain stem testing?

Answer 3

Patients should be established on an ITU with relative stability of respiratory and haemodynamic parameters.

There are certain pre-conditions that need to be met:

1. Evidence of irreversible brain injury of known aetiology
2. The patient should be in a coma, apnoeic and mechanically ventilated

Question 4

What are the potential red flags for brain-stem testing?

Answer 4

Potential ‘red flags’ mitigated or managed:

1. hypothermia - should be normothermic for 24 hrs
2. <6 hrs since loss of last brainstem reflex
3. <24hrs since loss of last brainstem reflex if primary anoxia
4. Steroids for space occupying lesion
5. Decompressive craniectomy
6. primary aetiology to brainstem or posterior fossa
7. prolonged fentanyl infusion
8. Patients with neuromuscular disorders

Question 5

What are the tests that take place in brain-stem testing?

Answer 5

Two doctors of more than 5 years GMC registered, one of whom is a consultant perform the tests. Two tests are performed, time of death is the time of completion of 1st confirmatory test.

Brain stem reflexes:

1. Pupil response to light (CN II, III)
2. Corneal reflex eyelid movement (CN V, VII)
3. Central response to painful stimulus (CN V, VII)
4. Caloric testing and eye movement (CN III, IV, VI, VIII)
5. Gag reflex (CN IX, X)
6. Cough reflex (CN X)

Apnoea test:

• pre-test gas pCO2 >6.0, pH <7.4
• apnoea test for 5 mins observation (connected to water’s circuit)
• post-test demonstrating pCO2 rise of 0.5
• re-recruitment and ventilated to meet pre-condition criteria

Question 6

What ancillary tests can be performed?

Answer 6

Can be used when a full clinical assessment cannot be performed (e.g. maxillofacial injuries, high cervical cord injuries).

Imaging:

• 4 vessel cerebral angiography
• transcranial doppler

Neurophysiology:

• EEG
• SSEPs

Question 7

What are the exclusion criteria for brain stem death testing?

Answer 7

Exclusion of potentially reversible causes:

1. CNS depressant drugs (caution with barbiturates and benzos) and NMB
2. Metabolic - Hypothermia <34oC
3. Circulatory - MAP <60
4. Biochemical:
   - Sodium <115 or >160
   - potassium <2
   - Mg and PO4 <0.5 or >3.0
   - glucose <3.0 or >20
5. Respiratory:
   - pH <7.35 or >7.45
   - pCO2 >6.0
   - pO2 <10.0

Question 8

What is post cardiac arrest/post-resuscitation syndrome?

Answer 8

4 key components:

i) Brain injury
ii) Myocardial dysfunction
iii) Systemic ischaemia and reperfusion response
iv) Precipitating pathology

Question 9

What is the management of patients post cardiac arrest?

Answer 9

Resuscitate in ABCDE approach

• Treat underlying cause
• Organ support and neuroprotection
• TTM 32-36 degrees for 24hrs
• avoid pyrexia for 72hrs
• Neuroprognostication not before 72hrs