@article{Ariturk_Okten_Ozgen_Erkek_Uysal_Gullu_Senay_Karabulut_Alhan_Toraman_2014, title={Utility of Cerebral Oxymetry for Assessing Cerebral Arteriolar Carbon Dioxide Reactivity during Cardiopulmonary Bypass}, volume={17}, url={https://journal.hsforum.com/index.php/HSF/article/view/905}, DOI={10.1532/HSF98.2014319}, abstractNote={<p><b>Background:</b> Our study evaluated changes in cerebral arterial oxygen saturation (rSO<sub>2</sub>) during cardiopulmonary bypass (CPB) that were caused by changes in arterial carbon dioxide tension (PaCO<sub>2</sub>).</p><p><b>Methods:</b> A group of 126 patients undergoing routine, elective, first-time coronary artery bypass graft surgery (CABG) was entered into a prospective study using bilateral near-infrared spectroscopy (NIRS) before anesthetic induction (T1), after anesthetic induction (T2), and continuing at 5-minute intervals during moderate hypothermic (32°C) CPB. Pump flows were set at 2.5 L/min/m<sup>2</sup> and adjusted to maintain mean arterial pressure (MAP) within 10 mmHg of the MAP recorded at the initial fifth minute of CPB (T3). Thirty-two patients were excluded from data collection because MAP could not be stabilized within the target range of 60-90 mmHg. In the remaining 94 patients, after obtaining steady state flow, MAP, and oxygenation, a trial period of hypocarbia (mean PaCO<sub>2</sub> of 30 mmHg) was induced by increasing oxygenator fresh gas flow rate (FGFR) to 2.5 L/min/m<sup>2</sup> (T4). A reciprocal period was then measured at reduced FGFR (0.75 L/min/m<sup>2</sup>) (T5).</p><p><b>Results:</b> After 20 minutes of a higher (2.75 L/min/m<sup>2</sup>) (FGFR), mean PaCO2 decreased from a baseline of 38 ± 4 mmHg to 30 ± 2 mmHg. This was associated with a parallel decrease (-10±9%) in mixed cerebral oxygen saturation without alteration of mean arterial oxygen tension (PaO<sub>2</sub>), lactate, MAP, CPB flow, or other parameters implying increased cerebral oxygen extraction.</p><p><b>Conclusion:</b> Parallel changes in PaCO<sub>2</sub> and rSO<sub>2</sub> occur during CPB when other variables remain constant, and are due to the effects of carbon dioxide on cerebral arterioles. Cerebral oxygen saturation measured by NIRS may be a useful indirect measure of PaCO<sub>2</sub> when continuous blood gas analysis is not possible during open-heart surgery. Cerebral oximetry values may be useful measurements for setting an optimum gas flow rate through the oxygenator.</p>}, number={3}, journal={The Heart Surgery Forum}, author={Ariturk, Cem and Okten, Murat and Ozgen, Zehra Serpil Ustalar and Erkek, Esin and Uysal, P?nar and Gullu, Umit and Senay, Sahin and Karabulut, Hasan and Alhan, Cem and Toraman, Fevzi}, year={2014}, month={Jul.}, pages={E169-E172} }