1. MEASUREMENTS OF SUBLINGUAL BLOOD VELOCITY AS A TOOL
FOR MONITORING SEPSIS
Leonard Winchester and Nee-Yin Chou
CW Optics, Inc.
Yorktown, VA

2. Sepsis Systemic inflammatory response to infection
750,000 cases / year in the US
33% mortality
Cost: x 1010 USD

3. Laser Speckle Imager

4. Speckle Contrast d = σ / <I> where I = average intensity
σ = standard deviation

5. Velocity Retrieval
<I> and σ are usually computed from straight-forward analysis of a small region centered at each pixel (7 x 7 box)
The second moment of intensity over an exposure T is given by

6. Velocity Retrieval where
Since the equation is an ensemble average, the Siegert relation between the first-order correlation function of the intensity and the second-order correlation of the electric field
where

7. Velocity Retrieval β is dependent on the speckle and pixel sizes
Two methods of finding β
Average identical images obtained with same value of T
Evaluate g2(τ) similar to the method of Nossal and Bonner for LDV

8. Velocity Retrieval
Additional benefit of the use of method based on LDV formalism of Nosal and Bonner is the inclusion of multiple scattering corrections.

9. Multiple Scattering

10. Human Subjects 20 Healthy Human Subjects Age: 30.7 ± 8.2 Male: 11
Caucasian: 12
Asian: 2
African-American: 6
Hispanic: 4

11. Protocol Heart rate, blood pressure, & oxygen saturation measured
Baseline measurements
Swish warm water
Hot measurement
Swish cold water
Cold measurement

12. Sublingual Image
B&W Image Speckle Imager
Subject 14

13. Effect of Exposure Time
2 ms ms
Subject 17

14. Effect of Temperature
Cold Normal Hot

15. Laser Doppler Imager

16. Mean Velocity

17. Mean Velocity

18. System Properties
Intra-Operator Error 5%
Inter-Operator Error 8%

19. Conclusion Effect of temperature
Velocity at elevated temperature is greater than velocity at normal temperature
Velocity at reduced temperature is faster than at normal temperature but not as fast as at elevated temperature

20. Support National Institute of General Medical Sciences GM079030
National Heart, Lung, and Blood Institute
HL059807
National Eye Institute
EY013672