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DOI: 10.1055/s-0029-1246670
The relation between preoperative cerebral oxygen saturation and variables of cardiopulmonary function in cardiac surgery patients
Background: Cerebral oxygen saturation (ScO2) monitoring by near-infrared-spectroscopy is used for intraoperative assessment of cerebral oxygen delivery/demand in cardiac surgery patients. A link between ScO2 levels, cardiac function and postoperative morbidity has been shown only retrospectively. This prospective study analyzes the relationship between preoperative ScO2 and baseline cardiopulmonary function as assessed by determination of left ventricular ejection fraction (LVEF), the plasma concentrations of NTproBNP and of highly-sensitive-troponin-t, (hsTNT) and glomerular filtration rate (GFR) in a large cohort of cardiac surgery patients.
Materials and methods: ScO2, NTproBNP, and hsTNT were determined preoperatively in 1180 consecutive patients when breathing oxygen enriched air to achieve transcutaneous oxygen saturation higher than 98%. GFR was calculated by the MDRD equation, LVEF was determined by angio- or echocardiography and was graded as normal, moderately or severely decreased.
Results: Correlation analysis revealed significant inverse correlations between ScO2 (after normalization of SpO2) and NTproBNP (r=–0.35 (–0.4 to –0.29; p<0.0001)) and hsTNT levels (r=–0.27 (–0.33 to –0.21; p<0.0001)), and positive correlations between ScO2 and GFR (r=0.21 (CI: 0.16 to 0.27; p<0.0001)) and LVEF-grading (r=0.16 (0.09 to 0.22; p<0.0001)). ScO2 levels were significantly different among the 3 LVEF classification groups (p<0.0001).
Conclusion: Preoperative ScO2 levels are reflective of cardiopulmonary function in cardiac surgery patients. These results support previous retrospective findings of an association between low ScO2 levels and a worse clinical outcome and thus should be taken into account when defining perioperative goals for ScO2 either during as well as after cardiac surgical procedures.