brain death and pitfalls - critical care canada forum · 2019. 9. 27. · of brain death •coma,...

©2016 MFMER | 3583470-1

Brain Death and Pitfalls

Eelco F. M. Wijdicks, MD, PhD

Division of Critical Care Neurology Mayo College of Medicine

©2016 MFMER | 3583470-2

Prerequisites Before Determination of Brain Death

• Coma, irreversible and cause knows

• Neuroimaging explains coma

• CNS depressant drug effect absent

• No evidence of residual paralysis

• No severe acid-base, electrolyte or endocrine abnormality

• Normal (or near normal) temperature ~ 36°C

• Systolic BP more than 100 mmHg

• No spontaneous respirations on ventilator

©2016 MFMER | 3583470-3

Brain Death Examination

• Motor response

• Brainstem reflexes

• Apnea test

• Document time of Death

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II III

V

VIIVIII

IXX

VI

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Abnormal flexion

Extensor response

No response

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Apnea (Oxygen-Diffusion) Test

20

40

60

80

100

0 2 4 6 8 10 12

PaC

O2

(mm

Hg

)

Duration of apnea (min)

Minutes of apnea

PaCO2Torr

pH

0

20

40

60

80

100

0 3 6 9 12 15

7.60

7.50

7.40

7.30

7.20

7.10

CP1174066-7

©2016 MFMER | 3583470-8

Precautions

• Core temperature

• ≥36°C

• Systolic BP

• ≥90 mm Hg

• Fluid balance

• Positive for 6 hours

©2016 MFMER | 3583470-9

Precautions

• Preoxygenate

• FiO2=1.0 for 10 min

• ventilation freq

• 10 breaths/min(tidal vol. 10 mL/kg)

• Arterial blood gas

• PO2 ≥200 mm Hg

• PCO2 ≥40 mm Hg

©2016 MFMER | 3583470-10

Precautions

• Disconnect ventilator

HR

ABPSpO2Resp

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Procedure

• Catheter at carina

• 100% O2 at 6 L/min

• Observe monitor, chest wall and abdominal wall for movement

HR

ABPSpO2Resp

©2016 MFMER | 3583470-12

Procedure

• No respiratory movements for 8 min

• Arterial blood gas

• If PCO2 ≥60 mm Hg or PCO2 increases >20 mm Hg

Brain death

• Reconnect ventilator

• 10 breaths/min

HR

ABPSpO2Resp

©2016 MFMER | 3583470-13

20

30

40

50

60

70

80

90

Pre Post50

150

250

350

450

Pre Post

mm

Hg

pO2

mm

Hg

pCO2

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Pitfalls(Drugs)

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Warning Signs in Brain Death

• Metabolic acidosis ( salicylates, ethylene glycol)

• Hypothermia

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Barbiturates and Alcohol

Phenobarbital 100 hr

Pentobarbital >24 hr

Alcohol 10 mL/hr

Below therapeutic range

Below legal limit of driving

CP1142806-43

©2016 MFMER | 3583470-17

Therapeutic Hypothermia after CPR

©2016 MFMER | 3583470-19

Estimates in Clearance Change in Drugs Used in Hypothermia for Cardiac Arrest

Percent per 1°C decrease

Midazolam 11

Remifentanil 6.3

Vecuronium 11.3

Fentanyl 6

Propofol 8

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Meta-Analysis 2002-2016 of CPR

• 274 studies

• 217 studies brain death not mentioned or excluded

• 26 studies

• Duration cardiac arrest mean 42 minutes

• 5% in conventional CPR and 9% in ECMO CPR

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Pitfalls(Spinal reflexes)

CP1142806-27

CP1142806-28

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Spinal Reflexes

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Pitfalls(Apnea test)

0

20

40

60

-5 0 5 10 15

Apnea Test

PCO2

Minutes

Disconnectionventilator

6 L O2transtracheal

BreathingTv 400 mL/f10

CP1174389-1

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0

20

40

60

80

100

Arterial PCO2 at breathing

PC

O2

(mm

Hg

)

Child

Adult

Lang/Heckmann

Ropper et al Wijdicks

Riviello et al

Paret et al

Levin/Whyte

Varis/Pollack

©2016 MFMER | 3583470-31

Our Experience With Apnea Testingn=228

No. %

Medically unstable 16 7

Apnea test aborted 7 3

Mild hypoxemia 10 4

Cardiac arrest 0 0

©2016 MFMER | 3583470-32

Factors Associated withAborting the Apnea Test

• T piece oxygen administration

• High flow oxygen (>10 L/min)

• High A-a gradient (>300)

• Hypotension (≤90 systolic blood pressure)

• Chest tubes for pneumothorax

©2016 MFMER | 3583470-34

0

5

10

15

20

25

30

A Last Resort Method?

• Gradual recruitment to PEEP of 25 cm H2O

• FiO2 of 1

• Every 3 minutes

• Oxygen flow 6L/min

• 20 cm H2O CPAP valve connected to a self inflating bag

©2016 MFMER | 3583470-36

PNEUMOTHORAX

• High oxygen flows (>6 L/min) or catheters pushed too far into the bronchial tree and wedged into a branch may trap gas

• Insertion of a catheter with sharp endings ( when cut) may damage the bronchial wall.

• High flows can cause dangerous wiggle in a catheter that has no side ports.

©2016 MFMER | 3583470-38

I Declared A Patient Brain Death

Phone call at night 6 hours later

“Patient triggers the ventilator”

©2016 MFMER | 3583470-41

“Over-breathing

ventilator”

Disconnection

apnea test

Decrease flow

sensitivity

Cardiac

oscillations

Water in

circuitLeaks

Switch to pressure

sensitivity

Find cause/

troubleshoot

©2016 MFMER | 3583470-46

Pitfalls ( Don’ts)

• Do not proceed if there could be a lingering effect of a sedative drug

• Do not proceed in the emergency department

• Do not use ancillary tests to solve your uncertainties

• Do not perform an examination if you have to look it up and just ask somebody else

brain death and pitfalls - critical care canada forum · 2019. 9. 27. · of brain death •coma,...

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