Effects of Pulsatile and Non-Pulsatile Cardiopulmonary Bypass Techniques in Coronary Artery Bypass Grafting Surgeries on Cerebral Perfusion.

Objective: We aimed to evaluate the effects of cardiopulmonary bypass (CPB) machines used in coronary artery bypass grafting surgeries on cerebral perfusion by performing cerebral oximetry monitoring [near-infrared spectroscopy (NIRS)], S100-ß protein measurements, and neurocognitive function assessment tests using both pulsatile and non-pulsatile modes. Methods: A total of 44 patients, 22 non-pulsatile (Group NP) and 22 pulsatile (Group P), were included in the study. Hemodynamic parameters, arterial blood gas values, NIRS values and blood S100ß protein levels were analyzed at five points: pre-induction (T1), initiation of CPB (T2), termination of CPB (T3), end of surgery (T4), and postoperative 24 h (T5). Two different neuropsychological tests were administered to patients in the preoperative and postoperative periods. Results: There were no significant differences between the groups for demographic characteristics such as age, gender, body mass index, aortic cross-clamping, CPB, and operation durations. The mean arterial blood pressure and PaO2 values for the T2 measurements were significantly higher in group NP (P < 0.05). Regional cerebral oxygen saturation (rSO2) (NIRS) values at T3 and T4 were significantly higher in group P (P < 0.05). Serum S100ß measurement values at T3 and T5 were significantly higher in group NP than in group P (P < 0.05). Serum S100ß protein levels at T3 correlate with rSO2 results. There was no statistically significant difference between the two groups in terms of pH, lactate, glucose, partial pressure of carbon dioxide, and peripheral oxygen saturation values. Conclusion: Despite no difference between the two groups for neurocognitive function tests, we believe that pulsatile perfusion may be more beneficial for cerebral perfusion when S100ß protein and NIRS values are considered. Further clinical studies are needed to evaluate the benefits of the pulsatile technique for cerebral perfusion.

Simplified calculation of mechanical power for pressure controlled ventilation in Covid-19 ARDS patients.

BACKGROUND: Mechanical power (MP) is a promising tool for guidance of lung protective ventilation. Different equations have been proposed to calculate MP in pressure control ventilation (PCV). The aim of this study is to introduce an easy to use MP equation MPpcv(m-simpl) and compare it to an equation proposed by Van der Meijden et al. (MPpcv) which considered as the reference equation in PCV. METHODS: Ventilatory parameters of 206 Covid-19 ARDS patients recorded between 24-72 hours after admission to intensive care unit. The PCV data from these patients were retrospectively investigated. MP in PCV was calculated with a modified equation (MPpcv(m-simpl)) derived from the equation (MPpcv) of Van der Meijden et al.: 0.098xRRx∆Vx(PEEP+∆Pinsp - 1). The results from MPpcv(slope), MPpcv(simpl), and MPpcv(m-simpl) were compared to MPpcv at 15 cmH2O ∙ s/L inspiratory resistance levels by univariable regression and Bland-Altman analysis. RESULTS: Inspiratory resistance levels at 15 cmH2O s/L was found to be correlated between the power values calculated by MPpcv(simpl)/MPpcv(m-simpl) and the MPpcv(slope)/MPpcv based on univariable logistic regression (R2≥98) analyses. In the comparison of all patients average MP values computed by the MPpcv(m-simpl) equation and the MPpcv reference equation. Bland-Altman analysis mean difference and p values at 15 cmH2O s/L inspiratory resistance values (J/min) were found to be MPpcv(m-simpl) vs MPpcv=-0,04 (P=0.014); MPpcv(slope) vs. MPpcv=0.63 (P<0.0001); MPpcv(simpl) vs. MPpcv=0.64 J/min (P<0.0001), respectively. CONCLUSIONS: The results of this study confirmed that the MPpcv(m-simpl) equation can be used easily to calculate MP at bedside in pressure control ventilated COVID-19 ARDS patients.