Cerebral Tissue Oxygenation Can Be Used Instead of Cerebral Intravascular Oxygenation to Study Cerebral Autoregulation in
Prematurely Born Infants
Ir. D. De Smet*, Lic. J. Vanderhaegen**, Prof. Dr. G. Naulaers**
and Prof. Dr. Ir. S. Van Huffel*
KATHOLIEKE UNIVERSITEIT LEUVEN, BELGIUM
*DEPARTMENT OF ELECTRICAL ENGINEERING (ESAT-SCD)
**NEONATAL INTENSIVE CARE UNIT, UNIVERSITY HOSPITALS LEUVEN
Introduction
Problem : impaired cerebral autoregulation Solution : detect ΔHbD concordant with ΔMABP (with ΔSaO
2=0)
1But …
Problem : HbD (=HbO
2-HbR) is not an absolute value
Solution : prove that TOI may replace HbD for measurement of impaired cerebral autoregulation
Acronyms :
• MABP : mean arterial blood pressure
• HbD : cerebral intravasc. oxygenation.
• SaO2 : arterial oxygen saturation
• TOI : cerebral tissue oxygenation
_____________________________________________________
[1] Tsuji et al., Pediatrics, 2000.
1. Introduction 2. Datasets 3. Methods
1. DC meth.
2. CPRT
3. Similarity meas.
4. Exp. results 5. Conclusion
Fig. : signals of interest
[%]
[mmHg]
[µMol/l]
[%]
Datasets
• 20 premature infants with need for intensive care
• MABP, SaO
2, HbD and TOI measured simultaneously in the first days of life at University Hospitals Leuven
• HbD and TOI measured by NIRS (with NIRO300, Hamamatsu)
• Post menstrual age of 28.7 weeks (24- 39)
• Weight : from 570 to 1470g
• Recording time : from 1h30 to 23h35
1. Introduction 2. Datasets 3. Methods
1. DC meth.
2. CPRT
3. Similarity meas.
4. Exp. results 5. Conclusion
Methods > DC methods
1. Introduction 2. Datasets 3. Methods
1. DC meth.
2. CPRT
3. Similarity meas.
4. Exp. results 5. Conclusion
• Correlation and (partial
1) coherence coefficients to look at the direct
concordance between signals MABP/HbD and MABP/TOI
• Frequency band of interest
2: 0 - 0.01Hz
• Sliding window approach
3: DC scores computed over 30-min epochs
2• SaO
2made constant
4______________________________________________________
[1] Leuridan et al, ASME design eng div conf and exhibit on mech vibration and noise, 1985.
[2] Tsuji et al., Pediatrics, 2000.
[3] Morren et al, Proc.23rd Annual Intern Conf IEEE Engineering in Med and Biol Society, 2001.
[4] De Smet et al, Proc. of the Belg. Day on Biomed. Eng. - IEEE/EMBS Benelux Symp, 2006
Fig. : sliding window approach
Fig. : DC scores
Methods > CPRT
Problem : the DC score value differs from one time instant to another one : not handy to use
Solution : a measure that synthesizes the level of autoregulation of a patient for the whole recording time
1,2: the critical percentage of the recording time
(CPRT)
____________________________________________________
[1] Tsuji et al., Pediatrics, 2000.
[2] Soul et al, Pediatric Research, 2007 1. Introduction
2. Datasets 3. Methods
1. DC meth.
2. CPRT
3. Similarity meas.
4. Exp. results 5. Conclusion
Fig. : CPRT
Methods > Similarity meas.
Aim : to prove that a signal may be replaced by another more handy one.
Particularly …
Question : may HbD (relative) be replaced by TOI (absolute) ?
Solution : derivation of similarity measures from the DC scores
Acronyms :
DC score : direct concordance score HbD : cerebral intravasc. oxygenation.
TOI : cerebral tissue oxygenation
1. Introduction 2. Datasets 3. Methods
1. DC meth.
2. CPRT
3. Similarity meas.
4. Exp. results 5. Conclusion
Fig. : linear regression
Experimental results
mCBS CB-
CPRT Mean
of |r| MSE
COH 0.76 0.81 0.027 0.0013
COR 0.63 0.71 0.043 0.0031
PCOH 0.70 0.78 0.041 0.0038
1. Introduction 2. Datasets 3. Methods
1. DC meth.
2. CPRT
3. Similarity meas.
4. Exp. results 5. Conclusion
Acronyms :
• mCBS : mean correlation between DC score curves
• CPRT : crit. percentage of the rec. time
• CB-CPRT : correlation between CPRT curves
• r : residual
• MSE : mean square error
Conclusion
• Definition of a new synthesized measure of cerebral autoregulation : the CPRT
• Derivation of similarity measures proving that TOI can be used to assess impaired cerebral autoregulation in neonates
1. Introduction 2. Datasets 3. Methods
1. DC meth.
2. CPRT
3. Similarity meas.
4. Exp. results 5. Conclusion
Conference
• Org. Committees
• Fin. Contributors
General Electric Company Linde Gas
Philips Medical Systems Gothia Medical AB
Bayer Schering Pharma Unisense A/S
Kodak Carestream Health Sciences Siemens Medical
Uppsala Kommun Uppsala University
PhD grant
• Fin. Contributors
Research Council KULeuven Flemish Government
Belgian Federal Science Policy Office
EU ESA
• Workgroup
Prof. Dr. Ir. S. Van Huffel Prof Dr. G. Naulaers Lic. J. Vanderhaegen
