Cerebral Monitoring after Asphyxia: Tissue Oxygenation and Cerebral Blood Flow
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Transcript of Cerebral Monitoring after Asphyxia: Tissue Oxygenation and Cerebral Blood Flow
Cerebral Monitoring after Asphyxia:Tissue Oxygenation and Cerebral
Blood Flow
Mioara D. Manole
University of PittsburghSafar Center for Resuscitation Research
Carnegie Mellon University, NMR Center for Biomedical Research
Aims for MNTP course
• To learn a variety of new methods for cerebral monitoring
– Cerebral oxygenation (Tissue sensors)– White matter tracts post injury (DTI)– Water content of the brain (DWI)– Cerebral microvasculature (two photon
microscopy)
Cerebral blood flow after pediatric asphyxial CA
ASL-MRI
STUDY GROUPS
CA
Sham
PREPARATION
Intubation
Catheters
BASELINE
CBF
ASL-MRI
9 MIN ASPHYXIA
RESUSCITATION
Chest compressions
Epinephrine
Sodium bicarbonate
Normal Saline
POST RESUSCITATION
Serial CBF
5, 10, 15, 30 min
1, 1.5, 2, 2.5 h
Regional CBF After Asphyxial CA in Immature 17 Day Old Rats*
SHAM CA
Baseline
5 min
15 min
30 min
10 min
1h
1.5 h
2 h
2.5 h*Manole et al, JCBFM 2009
Early hyperemia
(subcortical)
Hypoperfusion
(cortex)
Aim 1Assess brain tissue oxygenation in
cortex and thalamus
• Polarographic oxygen sensor• Assess the sampling volume of the oxygen
sensor• Measure brain tissue oxygen tension in cortex
and thalamus in our model of cardiac arrest
Oxygen sensor
• 10-50 μm tip
• can sample at cellular or vascular level
Air
Nitrogen in water
• 30 μm increments
• record pO2
Sampling volume for oxygen sensor
-Time constant
-Sampling volume
-Time constant 0.23 s
-Sampling volume 124 μm
PbO2 during Cardiac Arrest
0
10
20
30
40
50
60
70
80
Time (min)
Pb
O2
(mm
Hg
)
0.210.5 Asphyxia
-110
-90
-70
-50
-30
-10
10
30
CO
% C
HA
NG
E
0 100 200 300 400 500 600
Time (s)
PND 17
gasping
PbO2 after ROSC: Cortex
Time (min)
Baseline 0 5 10 15 30 60 120 150 180
Cor
tical
PbO
2 (
mm
Hg)
0
50
100
150
200
250
300
350
No anestesiaFentanyl
Twofold increase in PbO2 in the cortex
Decrease to values of 20 mm Hg after 30 min
Time (min)
Baseline 0 5 10 15 30 60 120 150 180
Tha
lam
ic P
bO2 (
mm
Hg)
0
50
100
150
200
250
300
350No anesthesiaFentanyl
PbO2 after ROSCThalamus
Fivefold increase in PbO2 in the thalamus
• DTI
• Two photon microscopy
Aim 2Explore other imaging modalities
DTI• DTI studio
• Explore DTI
Two photon microscopy
• Cortical vascular system
• Fluorescein Dextran injection
• Excitation 860 nm/ emission 500-500 nmprojections over the first 100um 300um
Carnegie Mellon University Pittsburgh NMR Center
Lesley Foley
Kevin Hitchens
Chien Ho
Safar Center for Resuscitation Research
Robert Clark
Patrick Kochanek
Hülya Bayır
Keri Feldman
Robert Hickey
Support: NIH K08HD058798 (MM), T32NS07485-02 (PMK), HD045968 (RSBC), P41EB-001977 (CH), Laerdal Foundation (MM)
Pittsburgh Center for Free Radical and Antioxidant Health
Valerian Kagan
Hülya Bayır University of Pennsylvania
William Armstead
Synzyme Technologies
Li Ma
Carleton Hsia
MNTP programSeong Gi Kim
Alberto Vasquez
Hiro Fukuta
Justin Crawley
Kwan-Jin Jung
Oxygen sensor– diffusion of oxygen through a
silicone membrane – oxygen reducing cathode
which is polarized against an internal Ag/AgCl anode
Ag + Cl- = AgCl + e- (anode)
O2 + 2H2O +4e- = 4 OH- (cathode)
Oxygen sensor
– The flow of electrons from the anode to the oxygen reducing cathode reflects linearly the oxygen partial pressure around the sensor tip
– The current is measured by a high quality picoammeter.
Oxygen sensor:response time and sampling
• Response time is influenced by:– Electrode diameter– Membrane thickness– Membrane diffusion coefficient
• Sampling distance 2-4 times tip diameter
Sampling from Cortex and Thalamus
– Cortex coordinates• 2 mm lateral • 1.5 mm deep • 3.14 mm posterior
– Thalamus coordinates• 2.5 mm lateral• 6 mm deep• 3.14 mm posterior
*
*
RA 50% Oxygen 100% Oxygen
Tha
lam
ic b
rain
tiss
ue P
bO2
(mm
Hg)
0
50
100
150
200
250
IsofluraneFentanyl
*
*
*
RA 50% Oxygen 100% Oxygen
Cor
tical
Bra
in T
issu
e O
2 (m
m H
g)
0
50
100
150
200
250IsofluraneFentanyl
PbO2 during resuscitation
-150
-100
-50
0
50
100
150
200
Pb
O2
(mm
Hg
)
CPR ROSC
22 s
PbO2 after ROSC: Cortex
Time (min)
Baseline 0 5 10 15 30 60 120 150 180
Cor
tical
PbO
2 (
mm
Hg)
0
50
100
150
200
250
300
350
No anestesiaFentanyl
Twofold increase in PbO2 in the cortex
Decrease to values of 20 mm Hg after 30 min
Time (min)
Baseline 0 5 10 15 30 60 120 150 180
Tha
lam
ic P
bO2 (
mm
Hg)
0
50
100
150
200
250
300
350No anesthesiaFentanyl
PbO2 after ROSCThalamus
Fivefold increase in PbO2 in the thalamus
Oxygen Titration in the Post Cardiac Arrest Period
Thalamic PbO2
Oxygen concentration (%)
50% 100% 21%
Tha
lam
ic P
bO2
(mm
Hg)
0
20
40
60
80
*
O2 sat 80%
Hb saturation- Rate limiting factor for
oxygen delivery?
Oxygen Titration in the Post Cardiac Arrest Period
Cortical PbO2
Oxygen concentration (%)
50% 100% 21%
Cor
tical
PbO
2 (m
m H
g)
0
20
40
60
80
*