Continuous Monitoring of Lactate Using Intravascular Microdialysis in High-Risk Cardiac Surgery: A Prospective Observational Study.

OBJECTIVE: To assess the accuracy and applicability of a novel system, not requiring calibration, for continuous lactate monitoring with intravascular microdialysis in high-risk cardiac surgery. DESIGN: Single-center prospective observational study. SETTING: City Hospital #1 of Arkhangelsk, Russian Federation. PARTICIPANTS: Twenty-one adult patients undergoing elective complex repair or replacement of two or more valves or combined valve and coronary artery cardiac surgery. INTERVENTIONS: After induction of anesthesia, in all patients a dedicated triple-lumen catheter functioning as a regular central venous catheter with integrated microdialysis function was inserted via the right jugular vein for continuous lactate monitoring using the intravascular microdialysis system. MEASUREMENTS AND MAIN RESULTS: Lactate values displayed by the microdialysis system were compared with the reference arterial blood gas (ABG) values. In total, 432 paired microdialysis-ABG lactate samples were obtained. After surgery, the concentration of lactate increased significantly, peaking at 8 hours (p<0.05). The lactate clearance within 8 hours after peak concentration was 50% (39%-63%). There was a significant correlation between Lactatecont and Lactatecont (rho = 0.92, p<0.0001). Bland-Altman analysis showed a bias (mean difference)±limits of agreement (±1.96 SD) of 0.09±1.1 mmol/L. In patients with postoperative complications, peak lactate concentration was significantly higher compared with those without complications: 6.75 (4.43-7.75) mmol/L, versus 4.20 (3.95-4.87) mmol/L (p = 0.002). CONCLUSIONS: Lactate concentration increased significantly after high-risk cardiac surgery. The intravascular microdialysis technique for lactate measurement provided acceptable accuracy and can be used for continuous blood lactate monitoring in cardiac surgery.

Monitoring of anesthetic depth during surgical correction of acquired valvular disorders: single center, randomized trial.

OBJECTIVE: The authors' primary objective was to test the hypothesis that Cerebral State Index (CSI)-guided control of anesthetic depth might reduce the consumption of anesthetics and shorten the duration of ICU and hospital stays after surgical correction of combined valve disorders. DESIGN: Single center, randomized trial. SETTING: City Hospital Number 1 of Arkhangelsk, Russian Federation. PARTICIPANTS: Fifty adult patients with combined valve disorders requiring surgical correction. INTERVENTIONS: The patients were randomized into 2 groups. In the CSI group, anesthetic depth was monitored, and the rate of infusion of propofol was titrated to maintain the depth of anesthesia corresponding to a CSI of 40-60. In the control group, the depth of anesthesia was monitored clinically, and the dosage of propofol was administered according to the recommendations of the manufacturer. MEASUREMENTS AND MAIN RESULTS: All patients received standard perioperative monitoring. Consumption of anesthetics and length of ICU and hospital stays were recorded. Preoperative patient characteristics did not differ significantly between the groups. In the CSI group, average intraoperative doses of midazolam and propofol were reduced by 41% and 19%, respectively (p<0.01). Maintenance of anesthesia guided by CSI shortened the time until fit for ICU discharge by 50% and reduced the lengths of ICU and postoperative hospital stays by 35% and 25%, respectively (p< 0.05). CONCLUSIONS: Monitoring of anesthetic depth reduces the requirements for midazolam and propofol, resulting in a faster recovery and a shorter postoperative ICU and hospital stay after surgical correction of combined valve disorders.

Normothermic cardiopulmonary bypass increases cerebral tissue oxygenation during combined valve surgery: a single-centre, randomized trial.

OBJECTIVES: In cardiac surgery, the choice of temperature regimen during cardiopulmonary bypass (CPB) remains a subject of debate. Hypothermia reduces tissue metabolic demands, but may impair the autoregulation of cerebral blood flow and contribute to neurological morbidity. The aim of this study was to evaluate the effect of two different temperature regimens during CPB on the systemic oxygen transport and the cerebral oxygenation during surgical correction of acquired heart diseases. METHODS: In a prospective study, we randomized 40 adult patients with combined valvular disorders requiring surgical correction of two or more valves into two groups: (i) a normothermic (NMTH) group (n = 20), in which the body core temperature was maintained at 36.6°C during CPB and (ii) a hypothermic (HPTH) group (n = 20), in which the body was cooled to a core temperature of 32°C maintained throughout the period of CPB. The systemic oxygen transport and the cerebral oxygen saturation (SctO2) were assessed by means of a PiCCO2 haemodynamic monitor and a cerebral oximeter, respectively. All the patients received standard perioperative monitoring. We assessed haemodynamic and oxygen transport parameters, the duration of mechanical ventilation and the length of the ICU and the hospital stays. RESULTS: During CPB, central venous oxygen saturation was significantly higher in the HPTH group but SctO2 was increased in the NMTH group (P < 0.05). Cardiac index, systemic oxygen delivery and consumption increased postoperatively in both groups. However, oxygen delivery and consumption were significantly higher in the NMTH group (P < 0.05). The duration of respiratory support and the length of ICU and hospital stays did not differ between the groups. CONCLUSIONS: During combined valve surgery, normothermic CPB provides lower central venous oxygen saturation, but increases cerebral tissue oxygenation when compared with the hypothermic regimen.