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Going Beyond the Gold Standard: Integrating new neuromonitoring technologies

to improve patient care

Diane Bräxmeyer Downey, RN BSN CNRN

Legacy Emanuel Medical Center Portland, OR

Disclosure

•  No financial relationships to disclose

•  This session provides a broad overview of available technology

•  Any reference to a specific brand or product is not intended as an endorsement, but rather a reflection of the device or product in which we are familiar.

Objectives

•  Identify limitations of traditional neuromonitoring devices

•  Describe emerging neuromonitoring technologies

•  Discuss the integration of traditional and newer neuromonitoring data on patient outcomes.

Historical Trepanning; from Greek trupanon, ‘borer’ •  Oldest surgical

procedure •  Transcultural •  Transcontinental •  Evidence of

survivability, multiple procedures on single human

Primary Injury

•  Damage that is complete at time of impact

Secondary Injury

•  Damage that continues to evolve after initial insult

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Secondary Injury

INFLAMMATION *éICP

* Edema

ISCHEMIA * Hypotension

* êHCT

HYPOXIA

INFECTION

METABOLIC *Hypercapnia *Acidosis *Release of

Neurotransmitters

Penumbra

Area of Infarct

Area of injured/at risk

tissue

Computed Tomography First ‘look’ •  Midline shift •  Mass or lesion

•  Infarct (time limiting) •  Hemorrhage

•  Ventricle size •  Grey/white

differentiation ONLY a SNAPSHOT! ***normal CT scan cannot exclude the presence of an elevated ICP as there is a high probability of false –negative results

Magnetic Resonance Imaging Uses magnetic fields and radio waves •  More soft tissue

detail •  Contrast less

nephrotoxic •  Incompatibility

issues

Monroe Kellie Doctrine

For any increase in volume in one compartment of the cranial contents, there must be a compensation in

another

Intraventricular ICP monitoring

Developed by Dr. Lundberg 1960’s

Advantages •  CSF drainage •  Waveform analysis •  Can re-zero •  Place @ bedside or OR •  Inexpensive Disadvantages •  Global pressure •  Accessing ventricle •  Clotting

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Intraparanchymal ICP monitoring Pressure is transduced through or fiberoptic fibers or microchip

Advantages •  Useful when ventricle

not accessible Disadvantages •  Cannot drain CSF •  Measures localized

pressure •  Drift; Cannot be

recalibrated inVivo

MAP • 70 – 110 mmHg

ICP • 5 – 15 mmHg

CPP • 60- 90 mmHg

Normal Values

ICP and CPP Limitations

Global vs localized ICP Optimal CPP •  Intact autoregulation •  Injured brain

Loss of the “Box”

ICP/CPP •  reference •  specificity

Pupilometry Cranial Nerve III

Pupil reaction

correlates with brainstem

oxygenation and perfusion

Parasympathetic

*constriction

Sympathetic *dilatation

Pupilometer

Digital Video of pupil response to light •  30 pictures per

second •  Multiple

measurements

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Pupilometer

Measures •  Baseline size (max) •  Constriction size(min) •  Percent change of

pupil size •  Latency •  Constriction velocity •  Dilatation velocity

Pupilometer

� NPiTM •  Scale 0-5 •  Score <3 indicates sluggish pupil and

abnormal pupillary response

NPiTM

Sluggish Normal Brisk

0 5 3 4 1 2

NR

NPi™ and ICP NPiTM and ICP

Pupil Size vs. Function Pupilometer Advantages

•  Noninvasive, portable •  QUANTITATIVE •  Good on dark irises,

pinpoint pupils •  Most ICU meds do not

affect light reactivity* •  RN performs

Disadvantages •  Cost of device •  Maintaining headsets •  Hand enter to EMR

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Variable Reported by

Pupilometer

Unit of Measure Definition/Calculation

Pupil Max/Min Size mm Minimum pupil size is the pupil size at the peak of the constriction. Maximum pupil size is the initial

resting pupil size and is defined by the mean pupil size during the latent period.

Constriction % or Percentage Change

% Constriction percentage is defined as maximum size minus minimum size divided by the maximum size.

Latency seconds Time difference between the initiation of retinal light stimulation and the onset of pupillary constriction.

Constriction Velocity mm/sec Amount of the constriction divided by the duration of the constriction; this results in a average velocity

Maximum Constriction

Velocity mm/sec Peak value of the velocity during constriction; this is

larger than the previous average velocity. Dilation Velocity mm/sec Amount of pupil size recovery (after the constriction)

divided by the duration of the recovery NPi

(Neurological Pupil index) Scalar

value Algorithm that takes all variables above as inputs and

compares to normative model to give a composite score of pupillary response

Optic Nerve Anatomy

•  Potential space •  Size increases

with edema

Optic Nerve Ultrasound

�  Measures Optic nerve sheath (ONS) diameter

�  ONS diameter > 0.5cm correlates to an ICP>20

�  95% specificity

(Rajajee, Neurocrit Care 2011)

Optic Nerve Ultrasound Advantages

•  Noninvasive •  Existing

equipment •  Low operator

variability

Disadvantages •  No optic nerve

injury •  Cannot predict

specific ICP value above 20

Near Infrared Spectroscopy (NIRS)

Uses near infrared light technology

Reflects the balance of oxygen delivery to oxygen consumption in a regional capillary tissue bed

Regional Saturation of Oxygen (rSO2) Capillary tissue bed

•  Arterial (75%) •  Venous (25%)

Intervention Trigger

<50 or >20% from baseline

Critical Threshold <45 or >25% from baseline

Normal: rSO2 60-80

Increases with a rise in delivery or a fall in demand

Decreases with a fall in delivery or an uncompensated rise in demand

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Supply and Demand Balance

Pain Fever

Shivering Seizure

Environmental Stimulus

Cardiac Output CPP FiO2 HCT

R/O mechanical obstruction

NIRS Advantages •  Noninvasive •  Continuous reading •  Requires caregiver

interpretation Disadvantages •  Site specific •  Limited depth •  Chromophore

influenced •  Requires caregiver

interpretation

Transcranial Doppler Measures velocity of flow in cerebral vasculature

Increased velocity =

vasospasm

Transcranial Doppler Advantages

•  Noninvasive •  Detection of

vasospasm •  Detection of

microemboli

Disadvantages •  Snapshot only •  Inaccuracy due to

loss/poor windows •  Special training

Continuous EEG Measures voltage fluctuations resulting from ionic

current flows within the neurons of the brain •  Detect subclinical seizures •  Can precede ICP increases

•  Identification of further deterioration

Continuous EEG Advantages •  Realtime continuous

read •  Non invasive •  Treatment of

subclinical pathology

•  Indications in post cardiac arrest

Disadvantages •  RN training •  CT/MRI

compatibility •  Cost

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Physical Exam What it tells you about the “black box”

Advantages •  Free •  Performed

anywhere •  Validator for

monitoring data

Disadvantages •  Operator

experience •  Consistency

Cerebral Oxygen Must be a constant supply

Delivery O2 Content Affinity

Venous Jugular Bulb

Fiber-optic catheter, placed retrograde in one of the internal jugular (IJ) veins Reflection of global cerebral oxygen Rarely used anymore

Intraparanchymal Cerebral Oxygen Monitor

Intraparanchymal catheter measures interstitial brain tissue oxygenation

Licox • Measures

partial pressure

• Assumes PbtO2 is a marker for adequate CBF

•  Individualize CPP goal

Licox Values

PbtO2 Value Indication

25-50 mmHg Adequate oxygenation

< 20 mmHg Cerebral hypoxia

<10 mmHg Severe cerebral ischemia

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PbtO2 < 20

•  Reduce ICP •  Increase CPP •  Check Airway •  Increase FiO2

•  Optimize CO •  Check Airway •  Adjust ventilator

•  éventilation •  éoxygenation

•  Euvolemia •  Consider transfusion

ICP > 20 mmHg ICP < 20 mmHg

PbtO2 Demand

ü Normothermia ü Sedation/Analgesia ü êEnvironmental Stimulus ü Shivering? ü Seizure?

Cerebral Perfusion

Different for intact vs. nonintact autoregulation

Each person’s ‘sweet spot’ is different

Make assumptions that 60 is a magic #

Cerebral Blood Flow Monitor Measures actual cerebral blood flow (CBF) in ml/100 g/min

Uses thermal conductivity Diminished Flow Vasospasm Tissue water content

Cerebral Vascular Resistance (CVR)

CBF = CPP/CVR

Cerebral Vascular Resistance

n 10

mmHg/ml/100gm/min

Probe

Three phases of Measurement

•  Temperature Stabilization •  Calibration •  Perfusion Measurement Takes approx. 7 minutes Cool down is flow dependent

Long cool down = Low Flow

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Hemedex Measurements

CBF = 20-35 ml/100g/min

K = 4.8 - 5.9 ΔT = 2.5 - 3.5 PPA = < 4.9

Cerebral Blood Flow Monitoring Advantages •  Realtime, continuous

monitoring •  Placed @ bedside •  Brain temp •  Early detection/

interventions Disadvantages •  Location specific •  Sensitive to nearby

chatter •  Unable to use when

brain temp>39.5 •  Not MRI compatible

Driving Practice

CBF = 20-35 ml/100g/min

K = 4.8 - 5.9 ΔT = 2.5 - 3.5 PPA = < 4.9

Driving Practice

Day 3

CBF = 20-35 ml/100g/min

K = 4.8 - 5.9 ΔT = 2.5 - 3.5 PPA = < 4.9

Cerebral Microdialysis

Measures local tissue chemistry of brain

FDA approved for bedside use in 2005 Indicates impact of tissue injury

Glucose

Pyruvate Lactate

NAD +

NADH NAD +

Citric Acid Cycle

Ischemia

ATP ATP ATP

ADP

ATP

Anaerobic Metabolism

Glucose

L/P ratio

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Lactate  #  Pyruvate  $  Glucose  $    Glutamate  #  Glycerol  #  

Cerebral Microdialysis

Mic

rodi

alys

is C

athe

ter

Cap

illar

y

Glycerol Reflects cell injury/lysis

Normal: 20-50 uM

êEdema

•  3% •  Fever control •  Stimulation •  Head position Glutamate

Reflects cell membrane breakdown

Normal: 10 uM

Glucose

Reflects available energy

Approx. 2/3

systemic glucose

Normal:

1.7 ± 0.9 mM

é  Systemic Glucose

•  Early enteral feeds •  Widen insulin gtt

parameters

Lactate

Reflects Cell Metabolism

Normal:

2.9 ± 0.9 mM

L/P Ratio

Reflects anaerobic

metabolism

Normal: 23 ± 4

é Available energy

•  Glucose •  CBF •  O2

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Driving Practice

Changes in LP ratio following depressive craniectomy

Driving Practice

Changes in LP ratio during vasospasm

Driving Practice

LP ratio changes in both ‘good’ and bad brain

Driving Practice

Changes in LP ratio in tight vs. loose glycemic control

Cerebral Microdialysis Advantages •  Early warning •  Evaluate

interventions •  Trigger for further

intervention •  Performed at

bedside Disadvantages •  Location sensitive •  POC Regulations •  No continuous read •  RN training

Current Controversies in Neuromonitoring

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BEST TRIP Trial

ü  No statistical difference between survival or functional outcome

ü  Shorter ICU stay, less interventions in ICP group

“Although it questions how we currently interpret the ICP values, it does not question their importance. For all centers, it solidly supports

that sTBI patients require aggressive treatment of intracranial pressure by whatever means is available”.- Dr. Randy Chestnut

•  Multi-center study •  324 pts; age 13 and older •  Treatment based on ICP

monitoring vs. Exam/Imaging

Benchmark Evidence from South American Trials: Treatment of Intracranial Pressure

TRACK- TBI Study

•  Multi center study @ 3 Level 1 facilities

•  135 pts. w/mild TBI •  CT scan on admission •  MRI about 1 week later

ü  99 had no detectable signs of injury on a CT scan ü More than a quarter (27) who had a “normal” CT

scans had focal lesions on MRI

Transforming Research and Clinical Knowledge in Traumatic Brain Injury

CT Radiation

ü 33% of patients underwent five or more lifetime CT examinations

ü 5% of patients had received estimated cumulative radiation doses that were higher than the radiation exposure from 1,000 chest X-rays.

ü 7% of the patients had enough recurrent CT imaging to raise their estimated cancer risk

•  Brigham and Women’s Hospital

•  31, 462 pts •  Retrospective 22 yr CT

exposure history BOOST 2 Trial

•  Phase 2 randomized clinical trial •  Median time when PbtO2<20mmHg

•  0.44 in the ICP group

•  0.14 in the ICP+PbtO2 group (p<0.00001)

NCS/SCCM Consensus Statement

•  Use of ICP and CPP protocol

•  Monitoring brain temp

•  Monitoring brain oxygen for all pts at risk for cerebral ischemia

•  Use of TCD to detect vasospasm in SAH

•  Use of EEG •  Altered LOC

•  Induced hypothermia

•  Use of cerebral microdialysis

Putting Neuromonitoring Devices into Practice

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Jimmy 14 year old wearing helmet

Unwitnessed bicycle crash on dirt trail

GCS on scene 6; intubated in field

Airlift to hospital

** Report of Concussion 6 Weeks PTA**

Initial Scan and Physical Assessment

•  CT scan: Large left basal ganglia hemorrhage

•  Small Right frontal contusion

•  Small SAH •  Nondisplaced left

mandibular fracture

Physical Exam

•  Sedated •  Fixed Dilated

Right pupil •  Moves hand

slightly to noxious stimuli

•  Temp 39.1, BP 126/61, HR 76

Initial Interventions

•  Foley placed

•  A line placed

•  Versed and Fentanyl Gtt

•  Right Frontal Camino

•  Opening ICP 19

TBI Goals 2007 Brain Trauma Foundation

•  CPP >50 mmHg •  Titrate MAP for CPP goal •  ICP <20 mmHg • Normothermic* •  PaO2 >75 •  Euvolemic • Na+ 140-150 mmEq/L

Hospital Day 3

•  Increasing ICP 24-28 mmHg

•  Left Temporal Craniectomy; flap out

•  Placement of Neuromonitoring devices: •  Microdialysis x 2; left parietal, left frontal •  Hemedex •  Licox •  Ventriculostomy

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Day 4: 0800-1100

BP 118-122/48-52 mmHg

MAP 64-70 mmHg

ICP 9-10 mmHg

CPP 54-61mmHg

CBF 21-26 ml/min

PbtO2 8.5-9.8 mmHg*

L/P ratio 26-28

Cerebral CBG 0.9-1 mmol/L

Midazolam gtt

Fentanyl gtt

Phenylephrine gtt

Day 4 @ 1140

Fentanyl Bolus IV given for anticipated

placement of weighted feeding tube

Day 4 @ 1200

•  BP 95-98/35-40

•  MAP 55-60

•  ICP 7-9

•  CPP 49-53

Hemedex •  9-10 ml/min

Licox •  8mmHg

L/P •  32

No alarms are generated; Is there a problem?

Day 4 @ 1400

•  BP 118-122/50-53 mmHg

•  MAP 65-72 mmHg

•  ICP 8-10 mmHg

•  CPP 55-65 mmHg

•  CBF 21 ml/min

•  PbtO2 10 mmHg

•  L/P ratio 36

The Bottom Line

•  No one monitor tells the whole story

•  Location

•  Context

•  Validation

•  Triggers additional assessment

•  ‘Sweet Spot’ targeted care

1.  Amini A, Kariman H, Arhami Dolatabadi A, Hatamabadi HR, Derakhshanfar H, Mansouri B, Safari S, Eqtesadi R: Use

of the sonographic diameter of optic nerve sheath to estimate intracranial pressure. Am J Emerg Med 2013, 31(1):236-239.

2.  Bader MK: Gizmos and gadgets for the neuroscience intensive care unit. The Journal of neuroscience nursing : journal of the American Association of Neuroscience Nurses 2006, 38(4):248-260.

3.  Bader MK, Littlejohns LR, March K: Brain tissue oxygen monitoring in severe brain injury, II. Implications for critical care teams and case study. Critical care nurse 2003, 23(4):29-38, 40-22, 44.

4.  Brain Trauma F, American Association of Neurological S, Congress of Neurological S: Guidelines for the management of severe traumatic brain injury. J Neurotrauma 2007, 24 Suppl 1:S1-106.

5.  Bullock R, Chesnut RM, Clifton G, Ghajar J, Marion DW, Narayan RK, Newell DW, Pitts LH, Rosner MJ, Wilberger JW: Guidelines for the management of severe head injury. Brain Trauma Foundation. European journal of emergency medicine : official journal of the European Society for Emergency Medicine 1996, 3(2):109-127.

6.  Cecil S, Chen PM, Callaway SE, Rowland SM, Adler DE, Chen JW: Traumatic brain injury: advanced multimodal neuromonitoring from theory to clinical practice. Critical care nurse 2011, 31(2):25-36; quiz 37.

7.  Chen JW, Gombart ZJ, Rogers S, Gardiner SK, Cecil S, Bullock RM: Pupillary reactivity as an early indicator of increased intracranial pressure: The introduction of the Neurological Pupil index. Surgical neurology international 2011, 2:82.

8.  Chen JW, Rogers SL, Gombart ZJ, Adler DE, Cecil S: Implementation of cerebral microdialysis at a community-based hospital: A 5-year retrospective analysis. Surg Neurol Int 2012, 3(57).

9.  Chesnut RM, Temkin N, Carney N, Dikmen S, Rondina C, Videtta W, Petroni G, Lujan S, Pridgeon J, Barber J et al: A trial of intracranial-pressure monitoring in traumatic brain injury. The New England journal of medicine 2012, 367(26):2471-2481.

10. Gerber LM, Chiu YL, Carney N, Hartl R, Ghajar J: Marked reduction in mortality in patients with severe traumatic brain injury. Journal of neurosurgery 2013, 119(6):1583-1590.

References:

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11.  Kampfl A, Pfausler B, Denchev D, Jaring HP, Schmutzhard E: Near infrared spectroscopy (NIRS) in patients with severe brain injury and elevated intracranial pressure. A pilot study. Acta neurochirurgica Supplement 1997, 70:112-114.

12.  Kristiansson H, Nissborg E, Bartek JJ, Andresen M, Reinstrup P, Romner B: Measuring elevated intracranial pressure through noninvasive methods: a review of the literature. J Neurosurg Anesthesiol 2013, 25(4).

13.  Peberdy MA, Callaway CW, Neumar RW, Geocadin RG, Zimmerman JL, Donnino M, Gabrielli A, Silvers SM, Zaritsky AL, Merchant R et al: Part 9: post-cardiac arrest care: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010, 122(18 Suppl 3):S768-786.

14.  Popovic D, Khoo M, Lee S: Noninvasive Monitoring of Intracranial Pressure. Recent Patents on Biomedical Engineeringe 2009, 2(3):165-179.

15.  Rajajee V, Vanaman M, Fletcher JJ, Jacobs TL: Optic nerve ultrasound for the detection of raised intracranial pressure. Neurocritical care 2011, 15(3):506-515.

16.  Rosenberg JB, Shiloh AL, Savel RH, Eisen LA: Non-invasive methods of estimating intracranial pressure. Neurocritical care 2011, 15(3):599-608.

17.  Springborg JB, Frederiksen HJ, Eskesen V, Olsen NV: Trends in monitoring patients with aneurysmal subarachnoid haemorrhage. British journal of anaesthesia 2005, 94(3):259-270.

18.  Taylor WR, Chen JW, Meltzer H, Gennarelli TA, Kelbch C, Knowlton S, Richardson J, Lutch MJ, Farin A, Hults KN et al: Quantitative pupillometry, a new technology: normative data and preliminary observations in patients with acute head injury. Technical note. Journal of neurosurgery 2003, 98(1):205-213.

19.  Zauner A, Muizelaar JP: Head Injury. London: Chapman and Hall; 1997.

References Continued

Thank You!

Diane Bräxmeyer Downey 503.413.4921

dbraxmey@lhs.org