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A931
October 19, 2009 2:00 PM - 4:00 PM Room Area M |
| Measurement of Absolute Viscerosomatic Tissue Oxygen Saturation: Preliminary Results |
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* David B. MacLeod, F.R.C.A., Richard J. Ing, M.B.B.Ch., F.C.A. (S.A.), Keita Ikeda, Ph.D., Warwick A. Ames, F.R.C.A., Scott R. Schulman, M.D. Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina |
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Introduction:
The purpose of this study is to validate the FORE-SIGHT® NIRS cerebral oximeter (CAS Medical Systems, Branford CT USA) when used to determine absolute viscerosomatic tissue oxygen saturation against weighted co-oximetry viscerosomatic venous and systemic arterial oxygen saturation.
Methods: The study population will include 65 pediatric subjects ≤ 18 years of age and ≥ 2.5 kg and ≤ 40 kg weight undergoing diagnostic cardiac catheterization at Duke pediatric cardiac catheterization laboratory. Four FORE-SIGHT medium or large size sensors, depending on subject weight, will be placed on the subject: one sensor below the right subcostal margin, one in the right 8th intercostal space (mid-axillary), one over the lower anterior abdominal wall (subumbilical) and one on the forehead. Venous (SVC, IVC, Hepatic vein [HV]) and arterial (femoral or radial) blood samples will be taken with the subject typically breathing air (F i O 2 = 0.21). Adherence to standard anesthetic practice will limit the potential confounding effects of anesthetic agents. Blood samples will be analyzed by a co-oximeter to obtain S a O 2 (femoral or radial) and S v O 2 for the target organ. For the liver, a hepatic tissue oxygen saturation (CX S ht O 2 ) value will be determined from co-oximetry measurements: CX S ht O 2 = [0.3 x S a O 2 ] + [0.7 x S hv O 2 ] (ref). The NIRS optically-derived S ht O 2 will be compared to CX S ht O 2 using linear regression. We will determine the relationship between viscerosomatic oxygen saturation to mixed venous (SVC) and cerebral oxygen saturations. Results: To date 4 subjects have completed the study (2M/2F; 3 Caucasian /1 African American; Age: 0.6-3.9 y; Weight 6.6-15.0 kg) 5 data points were analyzed (two NIRS sensors were placed on the liver for subject #4). A preliminary analysis shows a high correlation (p = 0.002) between NIRS S ht O 2 and CX S ht O 2 (Figure).[figure1]The table shows the measured oxygen saturation values for each subject. Of note, the hepatic S ht O 2 values were lower than the brain S ct O 2 values, as measured by NIRS, for 3 of 4 subjects.[figure2] Discussion: These preliminary results demonstrate the ability of NIRS to estimate absolute tissue oxygen saturation of the liver. The provision of accurate regional brain and viscerosomatic tissue oxygen saturations by non-invasive measurement could be of important clinical value in both the OR and ICU when treating critically ill pediatric patients. Reference: Pang CC, J Pharmacol Toxicol Methods. 2000;44(2):341-60. From Proceedings of the 2009 Annual Meeting of the American Society Anesthesiologists. |
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