depth of anaesthesia monitoring after subarachnoid haemorrhage... comfortably numb?

depth of anaesthesia monitoring after subarachnoid haemorrhage...

comfortably numb?

douglas duncanwestern general hospitaledinburgh

will cover

1. why we thought it would be useful

2. which patients we looked at

3. what we did

4.how we analysed the results, PK, sensitivities.

5. summary.

how did this happen?Melbourne 2002

Royal Melbourne Hospital

B-Aware Trial

return to UK

1. The patient must not move under any circumstances. TIVA and paralysed (at WGH), access to patient limited.

2. Many of these patients are of decreased conscious level prior to any anaesthetic being given. Underdose/Overdose.

3. The degree of surgical stimulation is probably very low.

4. Catastrophic intracerebral events – cerebroprotection.

5. We DO NOT think awareness is an issue.

GDC (Guglielmi Detachable Coils ) Anaesthesia - issues

why did we think this would be useful

Microcatheter is placed through the parent blood vessel into the lumen of the anuerysm.

GDC microcoils are placed through the microcatheter into the aneurysm lumen.

The coil is detached (fuse) from the pusher wire which is then removed. Additional coils are then placed sequentially until the aneurysm will not accept any more coils

GDC Anaesthesia – patients

• SAH within days• Vasospasm – conscious

level

• +/- SAH• recovered/good neuro

function

2 patient groups

1. elective.

2. emergency.

Methods and Materials

•MREC and LREC approval.•Patients undergoing ‘coiling’ recruited.•All had recent subarachnoid haemorrhage.•Total 38 patients.

•Standard monitoring.•ECG, Pulse, IBP, SpO2.•Datex-Ohmeda S/5 Monitoring.

•Propofol, remifentanil, atracurium anaesthetic.

•Entropy and Bispectral index monitoring.•Entropy M Module, BIS XP•Indices recorded /5seconds •Laptop PC•Datex-Ohmeda S/5 Collect software•All drug dosing and changes to infusion recorded manually.

Patient Demographics

age distribution of included patients

0

10

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30

40

50

60

70

80

0 5 10 15 20 25 30 35 40patient number

ag

e (

ye

ars

)

mean 53.7 yrs

male 12/38female 26/38

Average “bleed-coil” time = 4.95 days (min 1, max 22)Patient Demographics

0

5

10

15

20

25

30

nu

mb

er

of

pa

tie

nts

1 2 3 4 5

grade

WFNS grades

WFNS score1. GCS 15, No motor deficit or aphasia.

2. GCS 13-14, No motor deficit or aphasia.3. GCS 13-14, Any motor deficit or aphasia.

4. GCS 7-12, With or without deficit.5. GCS 3-6, With or without deficit

anaesthetist – blind to BIS/Entropy indices

why?

don’t know the numbers mean anything.

1.Presedation = 15secs data immediately prior to first sedative drug

2. LOC = 15 secs data, starting at no verbal response, no eyelash reflex

3. Intubation = 15 secs data starting 60 prior to ET tube passing through vocal cords

4. Stable = 15 secs data immediately prior to femoral catheter puncture

5. Eyelash return = 15 secs data after return of eyelash reflex only

6. Extubation = 15 secs data after patient extubated.

When did we take the data.......continuously but looking particularly at.....

= 6 clinically distinct depths

+ approx 75 hours data

Measuring the Performance of Anesthetic Depth Indicators.

Anesthesiology. 84(1):38-51, January 1996.

Smith, Warren D. PhD; Dutton, Robert C. MD; Smith, N. Ty MD

one of the properties of an ideal monitor includes;

1. Monotonicity – increasing clinically observed depth must always agree with increasing indicated depth.

PK describes this

PK

Measure of “degree of association”

is decreasing BIS/ENTROPY number associated with increasing clinical depth – ie is there concordance?

number between 0 and 1

1 indicates ideal concordance

0 indicates ideal discordance

0.5 equals a chance concordance.

original graphic Dutton, Smith, 1996

100 60 40 20 PK=1

100 100 70 100 PK 0.58

PK for deepening

PK for lightening

other points to note about PK

PK LOC

BIS 0.951

RE 0.862

SE 0.819

PK verbalBIS 0.89 – 0.91RE 0.83 – 0.88SE 0.81 – 0.86Vanluchene et alBJA Nov 2004

PK to eyelash regain

BIS 0.965

RE 0.913

SE 0.843

0

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100

pre-sedation LOC intubation stablereturn eyelash

extubation

BIS

0

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100

pre-sedation LOC intubation stablereturn

eyelash extubation

RE

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BIS

SE

RE

pre sedation LOC

pK BIS = 1.000pK RE = 0.444pK SE = 0.056

pt6 =53yo femaleSAH<24hrsGCS 15, WFNS gd1p comm aneurysm

0

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BIS

SE

RE

loss of eyelash reflex intubation 60 secs prepre sedation

56 year maleSAH day 4GCS 15 WFNS gd1MCA aneurysm

pk transition 1BIS 1.000SE 1.000RE 1.000

pk transition 2BIS 1.000SE 0.000RE 0.000

pk overallBIS 1.000SE 0.667RE 0.667

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1003

00

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BIS

Bispectral Index behaviour @ eyelash return

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RE

Response Entropy behaviour @ eyelash return

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10030

0

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120 90 60 30 0 30 60 90 120

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BIS

RE

eyelash return

secs

sens

itivi

ty

1-specificity

ROC curves reminder(Receiver Operative Characteristics)

1.0

1.0

http://www.anaesthetist.com/mnm/stats/roc/

ROC for all patients

• test to detect presence of eyelash reflex.•all indices very good•high sensitivity•high specificity

AUC SE

BIS 0.993 0.000

RE 0.974 0.001

SE 0.962 0.002

AUC SE

BIS 0.987 0.001

RE 0.982 0.002

SE 0.967 0.003

AUC SE

BIS 0.970 0.003

RE 0.900 0.011

SE 0.880 0.012

grade1

grade 2

grade 3

cut off sensitivityspecificit

y

60 0.966 0.959

69 0.949 0.966

66 0.927 0.974

52 0.930 0.969

56 0.951 0.974

51 0.900 0.975

60 0.886 0.954

56 0.869 0.958

72 0.848 0.976

Bispectral Index

available circa 1996

recent FDA approval – to reduce awareness

19% increased sales per year for 5 years

Profit this year

Improved platform XP

UK use of depth monitoring set to increase

AUC

0.823

maximum sensitivity = 72.7%maximum specificity = 78.5%cut off point = 99.4%

Summary..

1. BIS/Entropy – can be used in patients after subarachnoid haemorrhage.

2. Grade 1 and grade 2 patients works well.

3. Grade 3 patients (rarer) possibly some fall off in performance.

In our study,

BIS performed better than Entropy indices.

But Entropy;

a. Still functions very well.

b. May give advanced warning of light anaesthesia.

acknowledgements;

Keith Kelly – consultant anaesthetist WGH.Peter Andrews – consultant anaesthetist WGH.

Neuro anaesthetists/radiologists – WGH.

Theatre/angio suite staff WGH.

Lee Dalgety – Datex-Ohmeda.

F Duncan.

x rays

position

A Comparison of Frontal and Occipital Bispectral IndexValues Obtained During Neurosurgical Procedures

Toshie Shiraishi, MD, Hiroyuki Uchino, MD, Takeshi Sagara, MD, and Nagao Ishii, MDDepartment of Anesthesiology, Tokyo Medical University Hachioji Medical Center, Tokyo, Japan

25 patients – for clipping unruptured cerebral aneurysmspropofol/fentanyl anaesthesiacorrelation r2 = 0.9682 between occipital and frontalbut maintained at 40-60, little data on how monitors behaved outwith this area

properties of ideal anaesthetic depth monitor

Indicates the stage during light anaesthesia preceding conscious awareness

Real time presentation of results.

Closely reflects changing concentrations of anaesthetic agents and monotonic.

Able to stage the depth of anaesthesia for all anaesthetics on a common scale.

Practical and cost effective.lots of buts however…

ideal anaesthetic depth monitor, showing interindividual variability, but maintains monotonicity

0

10

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BIS

SE

RE

pre sedation loss of eyelash reflex intubation 45 secs pre

56 year maleSAH day 2GCS 15 WFNS gd1

transition 1pk BIS 1.000pk SE 1.000pk RE 1.000

transition 2pk BIS 0.389pk SE 0.000pk RE 0.000

overallpk BIS 0.796pk SE 0.667pk RE 0.667

cut off sensitivity % specificity% AUC (SE) sens+spec

BIS 61 94.85 96.06 0.989(0.0) 191

RE 66 93.68 95.96 0.966(0.1) 190

SE 66 89.72 97.36 0.952(0.2) 187Vanluchene et al BJA 93(5): 645-54 (2004)

BIS 63-74 177-182

RE 79-85 170-180

SE 73-77 174-180

ROC data for BIS RE SE.To detect difference between “anaesthesia” and awake/eyelash reflex present.

ROC Curve

Diagonal segments are produced by ties.

1 - Specificity

1.00.75.50.250.00

Sens

itivity

1.00

.75

.50

.25

0.00

Source of the Curve

Reference Line

SE

RE

BIS

Grade 2 Subarachnoid Haemorrhage

AUC SE

BIS 0.987 0.001

RE 0.982 0.002

SE 0.967 0.003

ROC Curve

Diagonal segments are produced by ties.

1 - Specificity

1.00.75.50.250.00

Sens

itivity

1.00

.75

.50

.25

0.00

Source of the Curve

Reference Line

SE2

RE2

BIS2

Grade 3 Subarachnoid Haemorrhage

AUC SE

BIS 0.970 0.003

RE 0.900 0.011

SE 0.880 0.012