potential organ donor post trauma

8/14/2019 Potential Organ Donor post trauma

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Introduction and purpose

The focus of trauma medicine is the immediate assessment and resuscitation of life-threatening injury, the

treatment of stable injury in a logical sequence of urgency, and the prevention of loss of function. In the

trauma setting it is apparent in a number of clinical situations that there is little likelihood of recovery from

severe injury. It is in this instance that an early consideration of the possibility of organ retrieval and

donation may follow the prior wishes of the injured patient and allow others an improved quality of life.

While full medical treatment is continued, the direction of medical management then turns toward the

diagnosis of brain death and the optimization of conditions for preservation of organ function and the

prevention of secondary damage.

This section will enable the reader to understand the issues of organ donor selection following trauma. It

will highlight the trauma that leads most often to a patient becoming an organ donor. It will provide

information on clinical and imaging techniques for early recognition of brain stem death, indicate the key

points in assessment of organ viability for transplant, and present the latest medical management of organdonors for optimizing organ function.

It is important to emphasize some general principles in brain death and organ donation.

Principles

Trauma is the commonest antecedent of patients who could provide organs for donation.

There are many organs that may be donated from brain dead patients or cadavers.

Organ donation is considered when it is evident that survival from the trauma event is not possible.

The possibility of organ donation should not influence medical management. It must be consistent with the

expected wishes of the trauma patient.

It is reasonable to initiate assessment for organ donation prior to determination of brain death.

An appropriate time interval should separate discussion with relatives of the impending death of the

patient, and the request for organ donation. The request for consent is an important step in organ

donation.

Formal Brain death testing should only occur after a suitable assessment period.

Brain death determination should be by selected individuals involved in the care of the patient but not

involved in organ harvesting or allocation.


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Identification of potential organ donors

Insufficient supply of organs.

There is great demand for transplantable organs as a result of progress in organ transplant medicine with

new surgical techniques and immunosuppressive drugs (Miranda et al. 1997). The high demand for organs

contributes to a rate of death on the transplant waiting list for heart, lung or liver transplants of around 20%

(Matesanz et al. 1996). There are 40,000 people awaiting a kidney transplant in Western Europe with the

supply being 5000 cadaver kidneys per year. Trauma hospitals have significantly higher levels of potential

for organ donation and significantly higher levels of performance in organ donation (Sheehy et al. 1996).

The majority of vascularized organ donation from trauma is from head injury. (Malagoni et al. 1996)

Improving donor rates

A number of methods have been proposed to improve donor rates. These include education of the public,

an opt out law of donor inclusion, required request legislation, education of medical professionals,

hospital organ donation development programmes, assessment and comparison of retrieval rates from

different institutions, coordinated retrieval programmes, and programs for the early detection of donors.

The use of organs with trauma related impairment, described as marginal organs, has also been

researched allowing a wider group of donor patients to be assessed for suitability. The application of

suitability limits for vascular organs gives a greater chance of accepting otherwise abandoned donor

organs (Wheeldon et al. 1994).

An important step in organ donation is for the attending physician to make a request to relatives for the

consideration of organ donation. A major cause of donation loss is from failure to request (Kennedy Jr. et

al. 1992). Separation of discussion of death and the request for organ donation is important in gaining

relative consent for donation (Garrison et al. 1991). Half of donation failures are family refusal and so it is

important to have training in the approach at the time of request (Werkman et al. 1991). There are

important differences in religious and cultural beliefs that affect the way people view organ donation. It is

best to be aware of these differences before approaching the family.

It is possible to improve organ donation rate at large urban trauma centres with a hospital development

program (OBrien et al. 1996). It may be useful to assess the trauma admission profile of each unit to gain

an expectation of what would be the organ donor rates from the record of cases through the unit. Organ

donation can occur from cadavers, in particular kidney and corneal grafts. For vascular organs, the

potential yield from non heart-beating blunt trauma victims is low and so may not be a direction for organ

donation from trauma to take (Wisner et al. 1996). Organ preservation techniques are allowing longerischaemic times for livers and are expected to allow longer preservation times for hearts and heart lung

grafts in the future.

Early recognition of potential organ donors in trauma

The first opportunity where potential donors are lost is the detection of people who can be diagnosed as

brain dead and hence could be considered as a potential organ donor. (Miranda B et al. 1997). The early


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recognition of terminal injury may allow greater salvage of organs. The commonest source of donor organs

is from head injury. Malagoni (1996) showed in a retrospective review of experience in a metropolitan level

1 trauma center that successful organ donation among patients without head injury comprised only 1% of

donations. Head injury leading to donation is primarily from traumatic injury, intracranial haemorrhage or

ischaemic injury, or from primary cerebral tumour (Table 34.1).

Traumatic head injury is commonly from motor vehicle crash, gunshot trauma, or blunt trauma. Malangoni

(1996) showed also that a 13% organ donation rate could occur from traumatic head injury when a second

organ system is involved in trauma.

In the trauma patient the early recognition of extensive brain injury is critical to management. It can be

predicted from the mechanism of injury, observed from the clinical state of the patient on primary

assessment, and confirmed on imaging. The early management of the injury is resuscitation, improvement

of function and prevention of secondary injury. At this point the focus is on the optimal management of the

brain injury and other injuries related to the trauma. This may initially require intravascular volumeresuscitation for haemodynamic stability but subsequently the restriction of fluid to reduce cerebral water

content, inducing a rise in plasma osmolarity, the maintenance of optimal haemodynamic indices and the

correction of developing complications of trauma. Where this is unsuccessful the management of the

patient following brain death is directed to continuing care to the primary condition but with a shift in focus

towards tissue perfusion and oxygenation, and anticipation of brain death physiologic sequelae (Robertson

et al. 1991).

The importance of the early recognition of terminal brain injury is that it will provide time for initiation of

assessment for suitability of organ donation. It is clinically clear when brain death is inevitable and

therefore reasonable to shift focus prior to formal confirmation of brain death. (Raper et al. 1995). This will

allow organ function to be optimized for the possibility of donation. To recognize brain death it is necessary

to have an understanding of coma in the trauma setting.

Coma definition and assessment

Coma is a state of unrousable unresponsiveness. (Myburgh et al. 1997). It is a state of impaired

consciousness that can be assessed from the patients activity spontaneously and in response to stimulus,

on presentation to the trauma unit. The Glasgow Coma Score (GCS) was developed to grade the severity

of head injury. It is a descriptive scale assessing the depth of unconsciousness (Table 34.2). A score of 15

indicates normal alertness and a score of 3 indicates a serious state of unconsciousness. It is influenced

by alcohol and drug intoxication, metabolic disturbance, and a specific scale for paediatric care has been

developed. Intubation for impaired consciousness will be required below a score of 10.

It is important to obtain a clear history of aetiology and time course of the injury. A traumatic aetiology and

several hours of observed coma in spite of treatment during transport to the trauma receiving room, it is

likely that significant injury is present and will need confirmation clinically and by radiological assessment.

The lowest GCS is 3 indicating no response to stimulus. When a score of 3 is combined with a severe


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isolated brain injury as its cause, then it indicates the possibility of impending brain death and the

contingency of organ donation should be considered. The presence of irrecoverable cerebral injury that

appears likely to progress to brain death prior to terminal circulatory failure or cardiac arrest requires the

consideration of organ donation (Scheinkestel et al. 1995). The recognition of irreversible cerebral injury is

integral in assessment brain death. Once reversible causes of coma are excluded and clear causation of

injury is identified then it is evident that the patient may progress to a persistent vegetative state, a locked-

in state, or brain death. These states exist with brain stem injury and must be distinguished from brain

stem death by careful assessment clinically, and with ancillary investigations.

It is necessary to identify early predictors of irrecoverable head injury on the initial assessment during the

first hours of emergency trauma care.

Prognostic features of severe brain injury

Is it possible to predict death from head injury? Attempts have been made to determine predictive indices

within 24 hours for the likelihood of death from severe traumatic brain injury. These have ranged from the

use of simple clinical indices (Mamelak et al. 1996) to more complex measurements such as heart rate

variability (Winchell et al. 1997). These studies aim to lift the assessment beyond clinical judgement to that

of a reliable, measurable, composite determinant. The clinical indicators for outcome from head injury are

as one would expect (Table 34.3). Mechanism of injury, the presence of associated injuries, age above 60

years (indicating the influence of underlying medical conditions and reduced physiologic reserve), GCS on

arrival of 3-5 (in coma it can be taken as best motor response = 1 or 2 out of 5), hypoxia, hypotension

(systolic blood pressure < 90mmHg), dilated pupils, and prehospital care have been shown as clinical

indicators for mortality or non functional outcome in trauma patients assessed on arrival (Combes et al.

1996, Fearnside et al., 1993, Celli et al. 1997, Quigley et al. 1997, Mamelak et al. 1996). Of these, age

above 60 years and a GCS motor score of 1 or 2 persisting for 12 hours have the best discrimination

(Mamelak et al. 1996). The need for ventilation and haemodynamic support is also an indicator of poor

outcome. (Celli et al. 1997, Waxman K et al. 1991). Radiological investigations that indicate poor prognosis

come from Angiography, Computerized Tomography, and Magnetic Resonance Imaging. Absent cerebral

flow is used by some American states as an ancillary diagnostic criterion for brain death. It provides rapid,

reliable diagnosis in adults. (Braum et al. 1997). Computerized Tomography findings indicating severity of

injury are the presence of extensive subarachnoid haemorrhage or intracerebral haemorrhage, loss of gray

white matter differentiation, midline shift and severe oedema (Fearnside et al. 1993, Waxman K et al.

1991). The combination of extensive injury on Computerized Tomography and GCS of 3 on arrival gives a

clear indication of likely mortality (Waxman et al. 1991, Kotwica et al. 1995). Emergency

Electroencephalogram assessment can be used to direct therapy in brain trauma, assist the diagnosis of

brain death (Legros et al. 1998) and indicate prognosis for closed head-injured patients (Thatcher et al.

1991).

It is generally accepted however that an early reliable prediction of death is not possible and that

resuscitation must be optimal regardless of initial neurologic status. (Chestnut RM 1997) (Waxman et al

1991). If cerebral function does not recover, adequate resuscitation is equally important for maintaining


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function of other organs for donation.

Clinical suspicion of brain death

The attending physician needs to have clear idea of impending brain death. The features of severe brain

injury are the presence of coma, apnoea, and clinical signs of brain stem injury (Table 34.4). The corticaland brain stem function can be ascertained by the response to clinical assessment at this point. The

presence of abnormal posturing and seizures indicates that brain stem death has not occurred but instead,

in the severe trauma setting, it indicates residual function that may progress to brain death.

Be alert to the appearance of brain stem dysfunction from alcohol, drugs abuse, prescription drugs

including mydriatic agents, previous ocular surgery, metabolic disease, hypothermia, and the differences

found in paediatric assessment.

Definition of brain death

Death is a biological event. It separates the process of dying from the process of disintegration (Bernat et

al. 1981). It is accepted as the cessation of respiration and circulation. Brain death is a legal definition of

death where one organ system, the brain, has reached a point of irreversible deterioration. This in turn will

lead to the disintegration of all other organ systems usually within days. Intensive medical support may

prolong this stage of disintegration. Disintegration occurs by ischaemic injury to organs, hypoxia,

hypothermia, haemodynamic instability and endocrine dysfunction.

Brain death is a state that is defined by the clinical criteria used to identify it. It is important that the formal

judgement on brain death is made by a clinician not primarily involved in the patient resuscitation to avoid

the suggestion of conflicting interest. The Australian and New Zealand Intensive Care Society Guidelines

(Pearson 1995) state that the primary responsibility of the attending physician is towards the patient. When

there is no expectation of recovery, and following the wishes of the patient given prior to their terminal

injury, it is the ethical and professional responsibility of the Intensive Care Specialist to support the process

of organ donation. It is clinically clear when brain death is inevitable and so it is reasonable to initiate a

discussion about organ donation prior to formal confirmation of brain death (Raper et al. 1995) but

important to separate the admission of impending death from the request for organ donation. The

conditions for legal brain death differ between countries but have similar basic requirements. These are

given in Table 34.5. The criteria vary throughout the medical community over the use of ancillary tests such

as CT, EEG and 4-vessel angiography but the conditions for brain death can be put simply:

1 the presence of a recognized proximate cause of brain injury

2 absence of clinical brain function

3 proof of no confounding intoxication

4 bedside testing for brain death usually repeated by the same individual at 6 to 24 hours.

The patient must have normal physiologic indices e.g. temperature, electrolytes, blood gases, blood

pressure, and the absence of pharmacological causes of coma e.g. sedative overdose or muscle


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paralysis. There must be sufficient time for diagnosis - at least 4 hours from injury and preferably 24 hours.

The examination must be by trained and approved physicians. It is important to remember that neonates

and children have specialized requirements for diagnosis of brain death.

Criterion for donor acceptance and organ assessment

Criterion for selection and exclusion

The general suitability of organ donation can easily be assessed. The criteria are firstly the prevention of

transmission of disease. This can be either malignant or infective disease. The second criterion is

acceptable function of the donor organ. A brief period of resuscitated cardiac arrest is acceptable for

putting a patient forward for organ donation. It is up to the receiving medical team to make the final

decision for the suitability of individual organs and this may only be possible with donor assessment in the

operating room by the retrieval team. It is best not to preempt the decision of organ suitability by excluding

the possibility of organ donation without first requesting advice. The general criteria for suitability are

summarized in Table 34.6. Acceptable age limits are widening for many organs in particular renal

transplantation. Cardiac, pulmonary, hepatic and renal impairment may be permissible if it occurred in

relation to admission trauma (Wheeldon et al. 1994, Sundaresan et al. 1995, Van der Werf et al. 1998).

Although primary brain tumours do not rule a patient out as an organ donor, it is important to ensure that it

is not a metastatic lesion from an unknown primary site. Viral infection history of CMV, Hepatitis B,

Hepatitis C may not preclude organ donation. The absolute contraindications are given in Table 34.7 for

specific organs. The relative contraindications require the decision of the retrieval team for consideration of

acceptability. Many tissues can be donated following death, especially corneas, and this should be

remembered as a consideration.

General preparation of patient for possible organ donation

The regional Transplant Coordinator will assist in the general preparation. They will interrogate a national

database to determine where organs should be directed. Medical care must be optimally maintained

during the period of investigation. The process may take many hours. The tests requested by the

transplant coordinator are given in Table 34.8. Contact should be made electively with the regional

transplant coordinators so their guidelines can be obtained and checked for which tests they consider

essential. It is a 24-hour service and usually has a single telephone number for contacting the service in

each state or region. There are specific tests that can assist individual organ assessment. These are given

in Table 34.9. The use of these will be directed by the retrieval team and the facilities available at the donor

hospital.

Medical management of organ donor

Understanding the physiologic changes of brainstem death

As the pathologic process of brain injury leads to brain death, there are a number of damaging physiologic

changes. These produce a generalized disintegration of body organs due to massive sympathetic

autonomic nervous system (ANS) activity followed by a failure of the hypothalamic-pituitary axis (Novitzky


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1996). Animal models of brain injury leading to brainstem death demonstrate a progressive and sequential

neurologic ischaemic injury beginning rostrally and extending caudally resulting from the pressure of

cerebral oedema pushing the brainstem into the foramen magna. This process is called coning (Shivalkar

et al. 1993). Initially there is a vagotonic effect of cerebral ischaemia followed by a sympathetic effect

producing hypertension and tachycardia (Cushings reflex). As the entire brainstem becomes ischaemic,

the sympathetic response becomes dominant and gives greatly increased cardiac output, blood pressure,

and heart rate. This may produce myocardial ischaemia and damage other donor organ function (Power,

Van Heerden 1995). It is followed by the onset of loss of vasomotor tone, arrythmias, hypotension, lowered

cardiac output, loss of inotropy and chronotrophy and the possibility of cardiac arrest prior to harvesting of

organs. Vascular capillary permeability is increased and may induce tissue interstitial oedema (Table

34.10).

Monitoring the patients haemodynamic state is to initially protect against ANS storm then support against

circulatory failure while avoiding excess fluid administration and maintaining moderate inotrope use.

Concurrently with cardiovascular changes there is loss of hypothalamic and pituitary control over

endocrine and metabolic function. Hypothalamic failure produces loss of temperature control and

hypothermia. Pituitary failure causes diabetes insipidus, a decrease in thyroid hormone, and a decrease in

cortisol levels found in these patients. Peripherally there is resistance to insulin action that leads to further

hyperglycaemia and metabolic failure. The relative hypothyroid state causes intracellular metabolism

failure and may impair graft organs. (Novitzky 1997). The endocrine dysfunction may lead to impaired

myocardial performance through reduction in thyroid hormone release. Electrolyte disorders will be

worsened by onset of diabetes insipidus. The replacement of these hormones is practised in some centres

of transplantation (Pickett et al. 1994, Novitzky 1997, Michler et al. 1996) and not in others (Scheinkestel

et al. 1995, Buckley 1997). The effect of thyroid hormone administration may be due to a phamacologic

property of thyroxine rather than a replacement of deficiency (Robertson et al. 1990), but has been shown

to have a cardioprotective effect in the recovery of myocardial function after human cardiopulmonary

bypass operations (Davis et al. 1993).

Common complications of brain death

The physiologic changes of brain death produce generalized organ system dysfunction and these are

presented in Table 34.11. The anticipation and treatment of these problems greatly enhances success of

organ transplant.

Management of donor

The management requires prevention of further injury, anticipation of complications, and recovery of organ

function. This involves monitoring the patient and continuing active clinical treatment after confirmation of

brain death. The focus shifts from cerebral resuscitation to the maintenance of donor organ function prior

to removal in order to give the best chance of achieving normal function following implantation.

In general the aim is the judicious use of intravenous fluid to avoid cardiac dilatation and interstitial


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oedema of the lungs, and prudent use of inotropes to maintain cardiac and circulatory function to give

adequate cellular perfusion and oxygenation. Guidelines are given in Table 34.13 for optimal measured

indices to increase chance of organ acceptability for grafting.

Monitoring

The ventilated brain dead patient requires invasive monitoring with arterial blood pressure, blood gas and

central venous pressure monitoring. Urine output needs hourly measurement with an indwelling catheter.

Central temperature measurement is necessary to anticipate hypothermia. The use of pulmonary flotation

catheters, transthoracic echocardiography, fibreoptic bronchoscopy and other organ assessment can lead

to appropriate use of fluid and inotropes that will encourage recovery of marginal organs (Wheeldon et al.

1994). The presence of impaired organ function resulting from the injury causing brain death may itself not

prevent acceptance of organs for donation as recovery can occur following transplantation. It is important

to have a reliable, large gauge intravenous access. Inotropes should be given into the central venous

circulation if required for more than brief periods. Blood transfusion may be necessary with CMV negative

blood or with the use of CMV filters. Table 34.12 gives a summary of recommended monitors.

Optimizing organ function and treatment of complications of brain death

The intention is to prevent complications, recover function and avoid inducing further injury. The rule of 100

for heart rate, systolic blood pressure and urine output has been provided as an optimal approach to

maintaining organ function in the brain dead patient awaiting organ retrieval (Power et al. 1995). This is a

useful starting point but there is evidence of benefit in assessment with a pulmonary artery flotation

catheter for determining functional recovery to standardized resuscitation for marginal organ donors

(Maclean et al. 1997). Recommended indices are given in Table 34.13. The indices are guidelines and

drug dosages used will depend on response to therapy. The concern over excessive inotrope

administration is the production of iatrogenic catecholamine-induced cardiomyopathy. The requirement for

tissue perfusion may require periods of higher dosage of inotrope infusion although it is important to

restrict inotrope dosage for cardiac donation. Predominant alpha-adrenergic vasopressors should be used

cautiously to avoid severe unopposed vasoconstriction. Isoprenaline produces tachycardia that may be

useful in paediatric donors because of their rate-dependant cardiac output. Aggressive fluid management,

warming, and treatment of Diabetes Insipidus may promote stability in paediatric cardiac donors (Finfer et

al. 1996). Paediatric donors may need greater dosage of inotrope to achieve adequate perfusion pressure

(Robertson et al. 1991). Intracranial injury produces ST and T wave changes that should not be confused

with myocardial ischaemia. Transthoracic Echocardiography and direct examination of the myocardium at

the time of harvesting will indicate the existence of ischaemic heart disease. Commonly there is right heart

dysfunction which may have serious implications in heart transplantation. Arrhythmias can develop from

multiple aetiology. This can be from the neurologic injury, electrolyte and respiratory disorders, drug

therapy, hypothermia, or direct trauma to the heart. They do not necessarily contraindicate cardiac

transplantation and treatment is indicated by the cause.

Minute ventilation and oxygen administration should be restricted to that required providing arterial

saturation >95% and normal arterial blood gases. Low ventilatory rates, low inflation pressures, and tidal


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volumes up to 15ml/kg facilitate lung preparation for donation. Minimizing the inspired oxygen

concentration and peak inspiratory pressure below 30cm H2O will reduce the risk of oxygen toxicity, in

particular for heart-lung block donation (Robertson et al. 1991). Neurogenic pulmonary oedema is a

sequelae of brain injury with the loss of capillary endothelial integrity and the movement of protein and fluid

into the alveolus. The early sign of this complication is the fall in oximetry and PaO2 with a rising FiO2.

Frequent suctioning and sputum collection for microbiological examination is important for predonation

assessment and provides valuable information for antibiotic use following implantation. Care must be

taken in avoiding introduction of nosocomial infection.

Endocrine dysfunction is managed by replacement of the Thyroxin, Cortisol, Insulin and Anti-diuretic

hormone (ADH). The appearance of polyuria with urine outputs of over 200ml per hour is managed with

infusions of ADH. Diabetes Insipidus is evidenced by a low urinary sodium content in the face of

hypernatraemia. The provision of ADH acts as to reduce water loss, maintain vascular tone, and assists

endothelial integrity. It may allow inotrope use to be minimized.

Relative hypothermia may be helpful in reducing organ metabolism at the time of organ donation. Severe

hypothermia will produce coagulopathy and haemodynamic instability, particularly in paediatric donors.

Normothermia is also necessary for the diagnosis of brain death.

There is some latitude in the possibility for donor organ recovery from traumatic injury. In particular the

kidneys are transplantable with a mildly elevated serum creatinine if it is a result of the terminal injury (Van

der Werf et al. 1998). They can be retrieved from cadavers although the shortest ischaemic time improves

recovery of kidney function. The heart can be transplanted from a state of moderate inotropic support if it is

shown to recover with optimized haemodynamic loading (Maclean et al. 1997, Wheeldon et al. 1994). The

lungs can be used with a pO2 less the 350mmHg on FiO2 of 1.0 and positive end expiratory pressure of 5

cmH2O for 15minutes if the cause is clearly defined or injury is in the contralateral lung. Hepatic function is

recoverable in cooled donors in the face of significant hypotension. Corneas are recovered from cadavers

after less than 12 hours, and skin and bone tissue can be recovered up to 24 hours following death.

Referring questions on organ suitability to the Regional Transplant Coordinator may be helpful and does

not constitute a commitment to provide donor organs.

Summary

One measure of excellence in a trauma service is its approach to the donation process. Consideration of

organ donation from the dead or dying trauma patient, where appropriate, is a standard of care. In a

trauma patients there are a great many different tissues for donation that can continue to support life after

the patients death.

Organ donation from brain dead trauma patients is usually in the context of head injury. It requires training

and experience in the assessment of brain death, great care in the management of the donor patient, and

immense consideration in the approach used when requesting the tissue. It requires respect for the trauma


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patient and their family.

The interests of the trauma patient are the paramount consideration, above the value of organ donation.

potential organ donor post trauma

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