Week 6: Organ Transplant Flashcards
(45 cards)
1
Q
Brain death diagnostic and declaration
A
- apneaic testing
- testing with cranial nervees
- diagnostics with brain imaging and brain blood flow: If the first 2 are inconclusive, then this one is done or under the age of 1
2
Q
Uniform determination of death act
A
- irreversible cessation of circulatory and respiratory function
- irreversible cessation of all functions of the entire brain, including the brain stem, is dead.
- A determination of death must be made in accordance with accepted medical standards.
3
Q
Diagnosis of Brain Death
A
- Brain death is a clinical diagnosis. It can be made without confirmatory testing if you are able to establish the etiology, eliminate reversible causes of coma, complete fully the neurologic examination and apnea testing.
- The diagnosis requires demonstration of the absence of both cortical and brain stem activity, and demonstration of the irreversibility of this state.
4
Q
- Severe head trauma
- Aneurismal subarachnoid hemorrhage
- Cerebrovascular injury
- Hypoxic-ischemic encephalopathy
- Fulminant hepatic necrosis
- Prolonged cardiac resuscitation or asphyxia
- Tumors
A
Etiology of Brain Death
5
Q
Exclusion of reversible medical conditions that can confuse the clinical assessment:
A
- Severe electrolyte, acid base and endocrine disturbance
- Absence of drug intoxication and poisoning
- Absence of sedation and neuromuscular blockade
- Hypotension (suppresses EEG activity and CBF)
- Absence of severe hypothermia (core temp < 35 C)
6
Q
What are the cranial nerve responses we see in brain death?
A
- No pupillary response to light. Pupils midline and dilated 4-6mm.
- No oculocephalic reflex (Doll’s eyes) – contraindicated in C- spine injury.
- No oculovestibular reflex (tonic deviation of eyes toward cold stimulus) – contraindicated in ear trauma.
- Absence of corneal reflexes
- Absence of gag reflex and cough to tracheal suction.
7
Q
Apnea Testing
A
- Once coma and absence of brain stem reflexes have been confirmed –>Apnea testing.
- Verifies loss of most rostral brain stem function
- Confirmed by: PaCO2 > 60mmHg, or PaCO2 > 20mmHg over baseline value.
- Testing can cause hypotension, severe cardiac arrhythmias and elevated ICP.
- Therefore, apnea testing is performed last in the clinical assessment of brain death.
8
Q
Following conditions must be met before apnea test can be performed:
A
- Core temp > 35.0 C
- Systolic blood pressure > 90mmHg.
- Euvolemia
- Corrected diabetes insipitus
- Normal PaCO2 ( PaCO2 35 - 45 mmHg).
- Preoxygenation (PaO2 > 200mmHg).
9
Q
Criteria for Brain Death in Children
A
- Neonate less than 7 days —> Brain death testing is not valid.
- 7 days – 2 months: Two clinical exams and two EEG 48 hrs apart.
- 2 months – 1 year: Two clinical exams and two EEG 24 hrs apart, or two clinical exams, EEG and blood flow study.
- Age > 1 year to 18 years: Two clinical exams 12 hrs apart, confirmatory study (Optional)
10
Q
Confirmatory testing is?
A
- Purely optional when the clinical criteria are met unambiguously.
- A confirmatory test is needed for patients in whom specific components of clinical testing cannot be reliably evaluated
- Incomplete brain stem reflex testing
- Incomplete apnea testing
- Toxic drug levels
- Children younger than 1 year old.
- Required by institutional policy
11
Q
Confimatory tests for Brain Death
A
-
Cerebral Blood Flow (CBF) Studies: Cerebral Angiography, Nuclear Flow Study
- you will see lack of blood flow to the brain - EEG (when brain scan is not utilized)
12
Q
What are the elements of brain death declaration after it is confirmed?
A
- Date
- Time
- Detailed documentation of Clinical Exam including specifics of Apnea Testing
- Physician signature
13
Q
Loss of brain stem function results in systemic physiologic instability including?
A
- Loss of vasomotor control leads to a hyperdynamic state.
- Cardiac arrhythmias
- Loss of respiratory function
- Loss of temperature regulation –> Hypothermia
- Hormonal imbalance –> DI, hypothyroidism
14
Q
Once brain death is declared therapy shift in emphasis from ___ to ____?
A
Therapy shifts in emphasis from cerebral resuscitation to optimizing organ fxn for subsequent transplantation.
15
Q
Without appropriate intervention brain death is followed by severe injury to most other organ systems within?
A
Circulatory collapse will usually occur within 48hrs.
16
Q
Brain death results in a massive release of?
A
Massive release of catecholamines, aka “autonomic storm”
17
Q
Phase 1 of autonomic storm
A
*Phase I: severe hypertension and increased systemic vascular resistance (Cushing response)
- Tachycardia
- Elevated C.O.
- Vasoconstriction
- Hypertension
18
Q
Phase 2 of autonomic storm
A
*Phase II: systemic vasodilation resulting in hypotension and loss of hypothalamic and pituitary function:
- Decreased levels of circulating Anti-diuretic Hormone
- Loss of thermoregulation
19
Q
Failure of the hypothalamus results in?
A
- Impaired temperature regulation - hypothermia or hyperthermia
- Leads to vasodilation without the ability to vasoconstrict or shiver (loss of vasomotor tone)
- Leads to problems with the pituitary …
20
Q
Pituitary failure results in?
A
- ADH ceases to be produced = Diabetes Insipidus
- Can lead to hypovolemia and electrolyte imbalances
- Leads to problems with the thyroid gland
21
Q
Thyroid failure leads to?
A
- Cardiac instability
- Labile blood pressure
- Potential coagulation problems
22
Q
Intensive care management of cardiovascular sytem rule of 100’s
A
- Maintain SBP > 100mmHG
- HR < 100 BPM
- UOP < 100ml/hr
- PaO2 > 100mmHg
23
Q
Aggressive fluid resuscitative therapy directed at restoring and maintaining intravascular volume.
A
Aggressive fluid resuscitative therapy directed at restoring and maintaining intravascular volume. SBP > 90mmHg (MAP > 60mmHg) or CVP ~ 10 mmHg.
24
Q
Respiratory effects of brain death
A
- Altered permeability of the pulmonary capillary bed
- High pulmonary artery pressures during autonomic storm
- Decreased osmotic gradient secondary to hypotonic fluid administration
- Adverse effects result in increased lung water
- Pre-existing risk factors for pneumonia and
- atelectasis
25
What is DIC and what is it also affected by?
* Results from the passage of necrotic brain tissue into the circulation
* Leads to coagulopathy and sometimes progresses further to DIC
* DIC may persist despite factor replacement requiring early organ recovery
* _Also affected by: _Hypothermia, release of catecholamines, hemodilution as a result of fluid resuscitation)
26
5 parts of organ donor management
* Hypertension ---\> Hypotension
* Excessive Urinary Output
* Impaired Gas Exchange
* Electrolyte Imbalances
* Hypothermia
27
Hypotension management
* Fluid Bolus – NS or LR ((Followed by MIVF (maitenance IV fluids) NS or .45 NS))
* Consider colloids
* Dopamine: increase contractility of the heart and promote vasoconstriction
* Neosynephrine: increase contractility of the heart and promote vasoconstriction
* Vasopressin: helps with urine output
* Thyroxine (T4 protocol)
28
Why use the T4 protocol
* Brain death leads to sudden reduction in circulating pituitary hormones
* May be responsible for impairment in myocardial cell metabolism and contractility which leads to myocardial dysfunction
* Severe dysfunction may lead to extreme hypotension and loss of organs for transplant
* T4 protocol reduces need for vasopressors and improves number of organs transplanted per donor and graft function
29
T4 Protocol
_Bolus_:
- 15 mg/kg Methylpred
- 20 mcg T4 (Levothyroxine)
- 20 units of Regular Insulin
- 1 amp D50W
_Infusion_:
- 200 mcg T4 in 500 cc NS
- Run at 25 cc/hr (10 mcg/hr)
- Titrate to keep SBP \>100
- Monitor Potassium levels closely!
30
Vassopressin and Vassopressin protocol
- Low dose shown to reduce inotrope use
- Plays a critical role in restoring vasomotor tone
_Vasopressin Protocol_
- 4 unit bolus IVP
- 1- 4 u/hour – titrate to keep SBP \>100 or MAP \>60
31
Diabetes Insipidus Management
* Treatment is aimed at correcting hypovolemia
* Desmopressin (DDAVP) 1 mcg IV, may repeat x 1 after 1 hour.
* Replace hourly U.O. on a volume per volume basis with MIVF to avoid volume depletion
* Leads to electrolyte depletion/instability monitor closely to avoid hypernatremia and hypokalemia
32
* Goal is UOP 1-3 ml/kg/hr
* Rule of thumb – 500 ml UOP per hour x 2 hours is DI
* Severe cases – Notify OPC. Assess clinical situation.
Diabetes Indipidus
33
Impaired Gas Exchange Management in Brain Death
* Maintain PaO2 of \>100 and a saturation \>95%
* Monitor ABG’s q2h or as requested by OPO
* PEEP 5 cm, HOB up 30o
* Increase ET cuff pressure immediately after BD declaration
* Aggressive pulmonary toilet (Keep suctioning & turning q2h)
* CXR (Radiologist to provide measurements & interpretation)
* OPO may request bronchoscopy
* CT of chest requested in some cases
34
Impaired Gas Exchange Goals
* Goals are to maintain health of lungs for transplant while optimizing oxygen delivery to other transplantable organs
* Avoid over-hydration
* Ventilatory strategies aimed to protect the lung
* Avoid oxygen toxicity by limiting Fi02 to achieve a Pa02 100mmHg & PIP \< 30mmHg.
35
ELECTROLYTE IMBALANCE MANAGEMENT (3 things)
_Hypokalemia_
-If K+ \< 3.4 – Add KCL to MIVF
(anticipate low K+ with DI & T4 administration)
_Hypernatremia_
-If NA+ \>155 – Change MIVF to include more free H20, ----Free H20 boluses down NG tube (this is often the result of dehydration, NA+ administration, and free H20 loss 2o to diuretics or DI)
_Calcium, Magnesium, and Phosphorus_
-Deficiencies here common…often related to polyuria associated with osmotic diuresis, diuretics & DI.
36
Hypothermia Management
- Monitor temperature continuously
- NO tympanic, axillary or oral temperatures. Central only.
- Place patient on hypothermia blanket to maintain normal body temperature
- In severe cases (\<95 degrees F) consider:
- warming lights
- covering patient’s head with blankets
- hot packs in the axilla
- warmed IV fluids
- warm inspired gas
37
Anemia treatment
* Hematocrit \< 30% must be treated
* Transfuse 2 units PRBC’s immediately
* Reassess 1o after completion of 2nd unit and repeat infusion of 2 units if HCT remains below 30%
* Assess for source of blood loss and treat accordingly
38
Overall Management Goals in Patients with Brain Death
* SBP 90-110 mmHg
* U/O 1-3 cc/kg
* HR 60-140
* PAWP (pulmonary artery wedge pressure) 7-12 mmHg
* Serum electrolytes WNL
* CBC and coags WNL
* SPO2 \>95%
* PaO2 90-110
* pH 7.35-7.5
* PCO2 25-45
* PF ratio \>300
39
Organ Preservation Time after being removed from the body
* Heart: 4-6 hours
* Lungs: 4-6 hours
* Liver: 12 hours
* Pancreas: 12-18 hours
* Kidneys: 72 hours
* Small Intestines: 4-6 hours
40
Second Brain Death note is ?
Official time of death
41
Indications for solid organ transplant (good candidates)
* Death within 12–24 months in the absence of an organ transplant
* _Unacceptable quality of life without transplant_: Intractable pruritis in progressive sclerosing cholangitis (PSC), Severe COPD
* _Potentially lethal complications of the underlying illness_: Intractable cardiac arrhythmia
* _Prevention of the manifestation of a genetic illness_: Familial Amyloid Polyneuropathy (FAP), Metabolic diseases of the liver
* All other forms of medical and surgical management have been tried and failed
42
Absolute Contraindications for Receiving Organ Donation
* Systemic and/or uncontrolled infection
* Active untreated or untreatable malignancy
* Post-transplant Lymphoproliferative Disease (PTLD) unless no active disease demonstrated by negative PET scan and resolved adenopathy on CT/MRI
* Active alcohol and/or other substance abuse Requires six months of documented abstinence through participation in a structured alcohol/substance abuse program with regular meeting attendance and negative random drug testing
* AIDS
* Inability to give informed consent
* Significant uncorrectable life-limiting medical conditions
* Irreversible severe brain damage
* History of non-compliance that has not been successfully remediated
43
Relative Contraidications for Receiving Organ Donations
* Recent graft loss
* Recent history of malignancy (treated) within five years
* Active psychiatric or behavioral disorder
* Remote history (more than six months in the past) of alcohol or substance abuse or occasional recreational use of marijuana
* Insufficient social (caregiver) support
* HIV infection without AIDS and with sustained CD4 counts \> 200/mm3
* BMI ≥ 35 kg/m2
* Chronic peptic ulcer disease, GI bleeding, diverticulitis
* High dose systemic corticosteroid use (\> 10mg prednisone/day or equivalent)
44
Minimum patient evaluation requirements for Organ Recipients
* Psychosocial evaluation and clearance
* Echocardiogram or MUGA with LVEF \> 40 percent OR cardiology clearance
* Colonoscopy (if indicated or \> age 50) with removal of any polyps
* Liver function tests (LFT) with transaminases ≤ 3x upper limit of normal and total bilirubin \< 2.5mg/dl
* HIV testing
* Hepatitis A, B and C serology
* Serum creatinine \< 2.5 mg/dl (≤ 1.5 mg/dl in children) or GFR \> 35 ml/min. If abnormal, may be eligible for a combined transplant
* Carotid Doppler ultrasound (with known coronary artery disease or \> age 50) — abnormal findings evaluated further; intervention and/or clearance required for abnormal findings
* Ankle-Brachial Index (ABI) (if indicated or \> age 50); ABI \< 0.95 may indicate peripheral artery disease (PAD); intervention and/or clearance required
* Dental examination; required dental work completed prior to transplant
* Ophthalmology examination (for diabetics) — baseline
* Mammogram (if indicated or \> age 40) — intervention and/or clearance required for abnormal findings
* GYN examination with Pap smear (if indicated or \> age 18) — intervention and/or clearance required for abnormal findings
* Immunizations up to date when indicated: Hepatitis A, Hepatitis B, influenza and pneumonia
45
Organ Allocation guidelines
* Children have priority over adults
* Body habitus
* Blood group
* Human leukocyte antigens (HLA) match
* High panel reactive antibody (PRA) score: highly sensitized recipients
