Brain stem death testing

Procedures vary internationally. In the UK clinical assessment of brain stem reflexes must be performed by 2 doctors who have been registered for >5 years. An EEG is required in other countries.

Pupillary light reflex

Pupils should appear fixed in size and fail to respond to a light stimulus.

Corneal reflexes

These should be absent bilaterally

Pain response

There should be no cranial response to supraorbital pain.

Vestibulo-ocular reflexes

After confirming that the tympanic membranes are clear and unobstructed 20ml iced water is syringed into the ear. The eyes would normally deviate toward the opposite direction. Absence of movement to bilateral cold stimulation confirms an absent reflex.

Oculo-cephalic reflexes

Also called 'doll's eye' reflexes. With the eyelids held open, brisk lateral rotation of the head normally produces opposite rotation of the eyeball as if to fix the gaze on an object. This rotation is lost in brain stem death.

Gag reflex

The gag reflex is absent in brain stem death. However, the gag reflex is often lost in patients who are intubated.

Apnoea test

While the reflex assessments are being performed the patient should be pre-oxygenated with 100% oxygen. The ventilator is disconnected and 6l/min oxygen is passed into the trachea via a catheter. Apnoeic oxygenation can sustain SaO2 for prolonged periods but there is an inevitable rise in PaCO2 which should stimulate respiratory effort. After 3-15min of disconnection blood gas analyses are performed until PaCO2 >6.7 kPa. Any respiratory effort negates the diagnosis of brain stem death.

Blood gas analysis, p100; EEG/CFM monitoring, p138; Urea and creatinine, p144; Electrolytes

, p146; Toxicology, p162; Opioid analgesics, p234; Non-opioid analgesics, p236; Sedatives, p238; Muscle relaxants, p240; Cardiac arrest, p272; Hypoglycaemia, p438; Hypothermia, p516; Care of the potential organ donor, p552

P.549

Withdrawal and withholding treatment

This is arguably the most difficult and stressful decision that has to be made for the critically ill patient. Withdrawal involves reduction or cessation of vasoactive drugs and/or respiratory support. In some ICUs the patient is heavily sedated and disconnected from the ventilator. Withholding involves non-commencement or non-escalation of treatment, e.g. applying an upper threshold dose for an inotrope and/or not starting renal replacement therapy.

Before approaching the patient/family, there should ideally be a consensus among medical and nursing staff that quantity and/or quality of life are significantly compromised and unlikely to recover. Often, the patient's viewpoint is very well-defined and the carers may rue the fact that the discussion was not initiated earlier.

Ethnic, cultural and religious factors will influence both doctor and patient/family in the timing and frequency of such decisions. In some societies doctors have a more paternalistic approach with little involvement of patient and/or family in the decision-making process. Others are overly inclusive, sometimes to the point of excessively acquiescing to the family's demands despite obvious futility in continuing care. Clearly, a balance needs to be struck that serves the best interests of the patient. Although potentially awkward, the mentally competent patient should be involved in the most important decision affecting their life. This should be done as considerately as possible, avoiding unnecessary distress. A series of discussions over several days may be needed, allowing time to contemplate. Consensus is reached with >95% of patients/families by the third discussion.

It should be stressed to the patient and family that care is not being withdrawn/withheld but that pain relief, comfort, hydration and general nursing care are to be continued. Likewise, no decision is binding but can be amended depending on the patient's progress, e.g. moving from withholding to withdrawal, or re-institution of full treatment. A 'negotiated settlement' is often a useful interim compromise for families unable to accept a withdrawal decision, whereby limitation of treatment is instituted and subsequently reviewed

Relatives can sometimes be very distraught and, occasionally, irrational on discussing withdrawal/withholding. For many, this will be their first experience of the dying process in a loved family member. A number of other factors including guilt, anger and within-family disagreements may also surface. It should be stressed that the withdraw/withhold decision should not be left to the family alone as this is an unfair burden for them to carry. Rather, it is their passive agreement with a medical recommendation that is being sought. The emphasis of the discussion is to inform them of the likely outcome and to seek their view of what the patient would want. They need to be dealt with both sensitively and honestly, and they should not feel pressured to give instant decisions.

Discussions should involve the patient's nurse and other involved carers as appropriate. It should be accurately documented in the case notes to ensure good communication between caregivers and act as source data should subsequent complaints surface.

Communication, p564

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Care of the potential organ donor

Patients with suspected brain stem death should be considered candidates for organ donation unless there is evidence of:

Cancer (except primary central nervous system)

• HIV or hepatitis surface antigen positive

• Uncontrolled sepsis

• Significant systemic disease

• Slow virus infection

The transplant co-ordinator should be contacted early (before the family are approached) to confirm likely suitability. If the family are amenable, the transplant co-ordinator will then initiate organ donation procedures. Do not reject those brain dead potential donors who, for example, have fully treated infections or acute renal failure without consultation with the transplant co-ordinator.

Management

1. Confirm brain stem death with appropriate testing.

2. Laboratory tests for blood group, HIV and hepatitis status and electrolytes.

3. Confirm organ donation is permissible by the coroner (or equivalent).

4. Maintain optimal cardiorespiratory status with fluid ± inotropes, optimal ventilation and physiotherapy. Diabetes insipidus should be treated with DDAVP.

5. Contact surgical and anaesthetic teams.

Organ suitability

• Kidneys—Age 4-70, acceptable U&E and creatinine

• Lungs — Age 0-50, acceptable CXR and blood gases

• Liver—Age 0-55, no alcohol or drug abuse, acceptable LFTs

• Corneas—Age 0-100, no previous intraocular surgery

The transplant co-ordinator will advise on other organ and tissue suitability, e.g. pancreas, trachea, bowel, skin.

Blood gas analysis, p100; Urea and creatinine, p144; Electrolytes

, p146; Colloids, p180; Inotropes, p196; Vasopressors, p200; Fluid challenge, p274; Hypotension, p312

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£ Ovid: Oxford Handbook of Critical Care

Editors: Singer, Mervyn; Webb, Andrew R.

Title: Oxford Handbook of Critical Care, 2nd Edition

Copyright ©1997,2005 M. Singer and A. R. Webb, 1997, 2005. Published in the United States by Oxford University Press Inc

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