Cerebral Near Infrared Spectroscopy during Cardiopulmonary Bypass Accurately Predicts Superior Vena Cava Oxygen Saturation

  • Dr Joseph Forbess, University of Texas Southwestern and Childrens Medical Center Dallas, United States
  • Mr Richard Ginther, niversity of Texas Southwestern and Childrens Medical Center Dallas, United States
  • Mr Rong Huang, Childrens Medical Center Dallas, United States
  • Dr Steven Leonard, niversity of Texas Southwestern and Childrens Medical Center Dallas, United States
  • Mr Ronald Gorney, niversity of Texas Southwestern and Childrens Medical Center Dallas, United States
  • Dr Kristine Guleserian, niversity of Texas Southwestern and Childrens Medical Center Dallas, United States

    • Background: Cerebral(CNIRS) and Flank(FNIRS) near-infrared spectroscopy are employed to monitor tissue oxygenation during cardiopulmonary bypass(CPB) in pediatric patients. We sought to validate these non-invasive measurements as predictors of oxygen saturation in the superior and inferior vena cava during CPB.

    Methods: 8 patients underwent elective repair of congenital heart defects with bicaval cannulation. Ultrasonic flow probes and oximetric catheters were placed in the superior and inferior vena caval limbs of the perfusion circuit. CNIRS, FNIRS, and 13 additional variables were recorded each minute on CPB. Relationships between these variables and superior vena cava oxygen saturation(SVCsat) and inferior vena cava saturation(IVCsat) were analyzed by linear mixed modeling. To assess NIRS as a trend indicator, the difference between consecutive vena cava oxygen saturations was regressed with the difference between consecutive NIRS oxygen saturations.

    Results: The mean number of observation time points per patient was 86(median 72, range 34 to 194) for 690 total observations. CNIRS was the strongest single predictor of SVCsat( p<0.0001). CNIRS predicted SVCsat value within ½ standard deviation(SD) at the rate of 47.3%. CNIRS was also a powerful indicator of changes in SVCsat(p<0.0001). FNIRS(p<0.0001) was the strongest single predictor of IVCsat, though it predicted IVCsat value within ½ SD at a rate of 26.4%, much lower than the CNIRS/SVCsat relationship. FNIRS also predicted IVCsat changes(p=0.02)

    Conclusion: CNIRS accurately predicts SVCsat and changes in SVCsat on CPB. The relationship between FNIRS and IVCsat is not as strong. Further investigation is warranted to determine the value of FNIRS measured during CPB.