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Background: Systemic hypothermia with bilateral antegrade selective cerebral perfusion (ASCP) is the preferred cerebral protective strategy for type A aortic dissection surgery. The optimal ASCP flow rate remains uncertain and the target flow cannot always be reached due to pressure limitations. The aim of this study was to assess the correlation between ASCP flow and regional cerebral oxygen saturation (rSO2)., Methods: A retrospective analysis was performed on 140 patients with acute type A aortic dissection who underwent surgery with moderate hypothermic circulatory arrest and bilateral ASCP between 2015 and 2021. Pearson correlation analysis was performed between ASCP flow and rSO2., Results: The median circulatory arrest duration was 46.5 (IQR:37.0-61.0) minutes. There was no significant correlation between ASCP flow and rSO2 for both the right (r = -.02, p = .851), and the left hemisphere (r = - .04, p = .618). The rSO2 values for ten patients who received > 10 mL/kg/min flow did not differ significantly from 130 patients who received 10 mL/kg/min or less for both the left hemisphere ( p = .135), and the right hemisphere ( p = .318). The ASCP flow was 5.1 (IQR:5.0- 6.5) mL/kg/min in five patients with, and 7.2 (IQR:5.8-8.3) mL/kg/min in 135 patients without a watershed infarction ( p = .098)., Conclusions: There was no correlation between ASCP flow rate and rSO2 in patients with acute type A aortic dissection. Furthermore, ASCP flow below 10 mL/kg/min was not associated with a reduction in rSO2. Definitive associations between ASCP flow and neurological outcome after type A aortic dissection surgery need further investigation., Competing Interests: Declaration of conflicting interestsThe authors received no financial support for the research, authorship and/or publication of this article.

Introduction: Accurate and precise management of blood gas parameters during cardiopulmonary bypass (CPB) is crucial to patient care and outcome. This study compares the data provided by Livanova B-Capta, Terumo CDI500, and Spectrum Medical M4 with the results from a gold standard blood gas analyzer to test accuracy., Methods: All three continuous blood gas monitoring (CBGM) devices were used simultaneously during CPB on one dedicated HLM. Arterial and venous blood samples of 40 adult patients who underwent elective cardiac surgery with CPB were taken from the CPB circuit., Results: Pre- and post-alignment deviation in percentages are compared with CLIA guidelines. B-Capta data reveals that the deviation pre-alignment is small and within the CLIA threshold for all parameters. Pre-alignment data for CDI 500 is within CLIA threshold for SvO2 and PaO2. The pre-alignment data for the M4 exceeds the CLIA thresholds for all parameters. Post-alignment data for B-Capta and CDI 500 reveals an accurate agreement for Hb and Hct and strong agreement for PaO2. All values for B-Capta and CDI 500 are within CLIA threshold values except for SvO2. Post-alignment the M4 exceeded the CLIA threshold value only for PaO2., Conclusion: B-Capta is the only CBGM device that operates within the CLIA guidelines and is in agreement with laboratory values prior to alignment.

Introduction: Carbon dioxide production (VCO2i), oxygen consumption and oxygen delivery can be monitored during cardiopulmonary bypass (CPB) as markers for tissue perfusion. This study examines if inline venous pCO2 (PvCO2) monitoring can be used as an alternative to exhaust gas pCO2 (ExCO2) to calculate VCO2i., Methods: PvCO2 and ExCO2 were monitored continuously during 40 elective coronary artery bypass grafting (CABG) procedures. VCO2i was calculated with ExCO2 as well as PvCO2., Results: Mean PvCO2 was 0.27 mmHg higher than mean ExCO2 (p < .001). The 95% limits of agreement of PvCO2 and ExCO2 were [-2.99, 3.53] mmHg which is within the limits proposed by the Clinical Laboratory Improvement Amendments of 2019. VCO2i was calculated using both PvCO2 and ExCO2 (PvVCO2i; ExVCO2i). A strong linear correlation was found for ExVCO2i and PvVCO2i (R2= .94, p < .001)., Conclusion: In conclusion, the differences in VCO2i calculation between the two methods are unlikely to be clinically relevant during normothermic CABG procedures. VCO2i can be calculated with either a capnograph or inline venous pCO2 monitoring.

This study investigated if current predictive values for increased lactate formation: VCO 2 i > 60 ml min -1  m -2 , respiratory quotient (RQ) > 0.90, and DO 2 /VCO 2  < 5.0, are valid under normothermic conditions. CO 2 derived parameters were analyzed in 91 patients undergoing normothermic CABG and related to increase of blood lactate concentrations during bypass. In this study population, 85 patients (93%) had a median VCO 2 i above 60 ml min -1  m -2 and 53 patients (58%) had a DO 2 /VCO 2  ⩽ 5.0. Eighteen patients (20%) had a median RQ ⩾ 0.90, but RQ remained with a maximum value of 0.94 below the biological threshold of 1.0. Increase of lactate concentrations remained without clinical significance and showed weak correlations with VCO 2 i (rs = 0.277, p = 0.008) and RQ (rs = 0.346, p = 0.001).The cohort was separated for the different CO 2 variables by their median value to compare increase in lactate concentration. Patients with a high VCO 2 i (⩾70 ml min -1  m -2 ) and a high RQ (⩾0.82) showed significant higher increase in lactate concentration compared to patients with VCO 2 i < 70 ml min -1  m -2 (p = 0.004), and a RQ < 0.82 (p = 0.012). Groups separated by a median DO 2 /VCO 2 of 4.8 did not show a difference in increase of lactate concentration in blood. In summary, specific CO 2 derived threshold values for the prediction of lactate formation, which have been reported in other studies, cannot be confirmed with our findings. However, a CO 2 production ⩾70 ml min -1  m -2 and a RQ ⩾ 0.82 in this study population were correlated with increased lactate formation. Because CO 2 production during bypass depends on patient temperature, a different cutoff value, that may take into account the influence of demographic variables, should be determined during normothermic CPB.