Start Of Cardiopulmonary Bypass Research Articles

The equilibrated blood sevoflurane concentrations show a rapid decrease after switching from ventilation for the human lung to cardiopulmonary bypass.

ABSTRACTVolatile anesthetics (VAs) protect myocardial cells during cardiovascular surgeries, including cardiopulmonary bypass (CPB). In CPB, blood is gradually transferred from the body to a CPB unit until the target cardiac index is achieved, following which human lung (HL) ventilation is stopped. This pilot study aimed to evaluate changes in the blood sevoflurane concentrations 5 min after the start of CPB when its delivery to the oxygenator began after HL ventilation with sevoflurane was completed. Six patients were recruited and participated in this study. For each patient, the equilibrated blood sample, collected 20 min after starting the delivery of 1.7% sevoflurane (HL group), and another blood sample, collected 5 min after starting the CPB, were analyzed using gas chromatography equipped with a flame ionization detector. The mean (± standard deviation) sevoflurane concentrations in the HL and 5 min after starting CPB groups were 58.6 ± 4.7 and 14.5 ± 5.0 μg/ml, respectively (P < 0.01). In conclusion, the equilibrated blood sevoflurane concentrations showed a rapid decrease when switching from sevoflurane ventilation for the HL to CPB unless it was introduced to the oxygenator until completion of the switch.

The effect of selective cerebral perfusion on cerebral versus somatic tissue oxygenation during aortic coarctation repair in neonates and infants

BackgroundSuboptimal tissue perfusion and oxygenation may be the root cause of certain perioperative complications in neonates and infants having complicated aortic coarctation repair. Practical, effective, and real-time monitoring of organ perfusion and/or tissue oxygenation may provide early warning of end-organ mal-perfusion.Methods Neonates/infants who were scheduled for aortic coarctation repair with cardiopulmonary bypass (CPB) and selective cerebral perfusion (SCP) from January 2015 to February 2017 in Children’s Hospital of Nanjing Medical University participated in this prospective observational study. Cerebral and somatic tissue oxygen saturation (SctO2 and SstO2) were monitored on the forehead and at the thoracolumbar paraspinal region, respectively. SctO2 and SstO2 were recorded at different time points (baseline, skin incision, CPB start, SCP start, SCP end, aortic opening, CPB end, and surgery end). SctO2 and SstO2 were correlated with mean arterial pressure (MAP) and partial pressure of arterial blood carbon dioxide (PaCO2).ResultsData of 21 patients were analyzed (age=75±67 days, body weight=4.4±1.0 kg). SstO2 was significantly lower than SctO2 before aortic opening and significantly higher than SctO2 after aortic opening. SstO2 correlated with leg MAP when the measurements during SCP were (r=0.67, p<0.0001) and were not included (r=0.46, p<0.0001); in contrast, SctO2 correlated with arm MAP only when the measurements during SCP were excluded (r=0.14, p=0.08 vs. r=0.66, p<0.0001). SCP also confounded SctO2/SstO2’s correlation with PaCO2; when the measurements during SCP were excluded, SctO2 positively correlated with PaCO2 (r=0.65, p<0.0001), while SstO2 negatively correlated with PaCO2 (r=-0.53, p<0.0001).Conclusions SctO2 and SstO2 have distinct patterns of changes before and after aortic opening during neonate/infant aortic coarctation repair. SctO2/SstO2’s correlations with MAP and PaCO2 are confounded by SCP. The outcome impact of combined SctO2/SstO2 monitoring remains to be studied.

Vancomycin concentrations during cardiopulmonary bypass in pediatric cardiac surgery: a prospective study.

Few data are available regarding intraoperative plasma concentrations of vancomycin administered as prophylaxis in pediatric cardiac surgery. The aims of this study were to investigate during pediatric cardiac surgery with cardiopulmonary bypass(CPB) the attainment of the area-under-the-curve of the vancomycin serum concentrations versus time over surgery to minimum inhibitory concentration ratio(AUCintra/MIC) of 400 (mg × h)/l and/or a target concentration of 15-20 mg/l. In a prospective study, 40 patients divided into four subgroups (neonates, infants, children <10 years-old, ⩾10 years-old) undergoing cardiac surgery with cardiopulmonary bypass (CPB) were enrolled. A slow vancomycin bolus of 20 mg/kg, up to a maximum dose of 1000 mg was administered before skin incision and a further dose of 10 mg/kg (up to 500 mg) at CPB start. Vancomycin samples were collected intraoperatively at four time points. The median (interquartile range) age was 241.5 days (47-3898) and the median weight was 7.1 kg (3.1-37). The median AUCintra/MIC was 254.73 (165.89-508.06). In 11 patients the AUCintra/MIC target was not reached. Neonates displayed the lowest AUCintra/MIC values, and these were significantly lower than those of children ⩾10 years old (p = 0.02). Vancomycin concentrations were above the maximal target of 20 mg/l in 82.5% and 80% of patients at surgery and CPB start, respectively. At CPB and surgery end, 42.5% of patients showed vancomycin concentrations above 20 mg/l and 42.5% below 15 mg/l. Patients⩾10 years old showed the highest peak values whereas neonates were those with the lowest troughs. AUCintra/MIC correlated with age(r:0.36, p = 0.02), weight(r:0.35, p = 0.03), intraoperative protein value(r:0.40, p = 0.01), CPB priming volume/kg(r:-0.33, p = 0.04), CPB duration(r:0.36, p = 0.02) and vancomycin troughs(r:0.35, p = 0.04). An AUCintra/MIC ⩾400 target was not reached in one-quarter of children undergoing heart surgery. Vancomycin peaked before the start of surgery and neonates were those with the lowest troughs. Vancomycin concentrations are affected by CPB hemodilution and by patients' age and weight.

Levosimendan Versus Milrinone and Release of Myocardial Biomarkers After Pediatric Cardiac Surgery: Post Hoc Analysis of Clinical Trial Data.

We compared the effect of two inodilators, levosimendan and milrinone, on the plasma levels of myocardial injury biomarkers, that is, high-sensitivity troponin T and heart-type fatty acid binding protein, and on N-terminal prohormone of brain natriuretic peptide as a biomarker of ventricular function. We hypothesized that levosimendan could attenuate the degree of myocardial injury when compared with milrinone. A post hoc, nonprespecified exploratory secondary analysis of the Milrinone versus Levosimendan-1 trial (ClinicalTrials.gov Identifier: NCT02232399). Two pediatric tertiary university hospitals. Infants 1-12 months old, diagnosed with ventricular septal defect, complete atrioventricular septal defect, or Tetralogy of Fallot undergoing corrective surgery with cardiopulmonary bypass. Seventy patients received a loading dose of either levosimendan or milrinone at the start of cardiopulmonary bypass followed by an infusion of the respective drug, which continued for 26 hours. Plasma levels of the three cardiac biomarkers were measured prior to the initiation of cardiopulmonary bypass and 2, 6, and 24 hours after weaning from cardiopulmonary bypass. In both groups, the levels of high-sensitivity troponin T and heart-type fatty acid binding protein were highest at 2 hours post cardiopulmonary bypass, whereas the highest level of N-terminal prohormone of brain natriuretic peptide occurred at 24 hours post cardiopulmonary bypass. There was no significant difference in the biomarkers' plasma levels between the study groups over time. Neither was there a significant difference in the postoperative peak plasma levels of the cardiac biomarkers. In this post hoc analysis of the MiLe-1 trial, there was no demonstrable difference in the postoperative cardiac biomarker profile of myocardial injury and ventricular function when comparing infants managed in the perioperative period with levosimendan versus milrinone.

Population pharmacokinetic evaluation of cefuroxime in perioperative antibiotic prophylaxis during and after cardiopulmonary bypass.

The purpose of this study was to explore pharmacokinetic and pharmacodynamic aspects of a contemporary dosing scheme of cefuroxime as perioperative prophylaxis in cardiac surgery using cardiopulmonary bypass (CPB). Cefuroxime plasma concentrations were measured in 23 patients. A 1.5-g dose of cefuroxime was administered at start of surgery and CPB, followed by 3 additional doses every 6 hours postoperative. Drug levels were used to build a population pharmacokinetic model. Target attainment for Staphylococcus aureus (2-8 mg/L) and Escherichia coli (8-32 mg/L) were evaluated and dosing strategies for optimization were investigated. A dosing scheme of 1.5 g cefuroxime preoperatively with a repetition at start of CPB achieves plasma unbound concentrations of 8 mg/L in almost all patients during surgery. The second administration is critical to provide this level of coverage. Simulations indicate that higher unbound concentrations up to 32 mg/L are reached by a continuous infusion rate of 1 g/h after a bolus of 1 g. In the postoperative phase, most patients do not reach unbound concentrations above 2 mg/L. To improve target attainment up to 8 mg/L, the continuous application of cefuroxime with infusion rates of 0.125-0.25 g/h is simulated and shown to be an alternative to bolus dosing. Dosing recommendations for cefuroxime as perioperative antibiotic prophylaxis in cardiac surgery are sufficient to reach plasma unbound concentration to cover S. aureus during the operation. Target attainment is not achieved in the postoperative period. Continuous infusion of cefuroxime may optimize target attainment.

Effect of cardiopulmonary bypass on the development of acute kidney injury after open-heart surgery

THE AIM. Assessment of factors associated with cardiopulmonary bypass (CPB) in acute renal dysfunction in patients in the early postoperative period after cardiac surgery. PATIENTS AND METHODS. Monocentric observational study in patients (n = 97) who underwent elective open-heart cardiac surgery (coronary artery bypass grafting -50.44 %, aortic valve prosthetics – 31.04 %, mitral valve prosthetics – 12.61 %) using cardiopulmonary bypass. Inclusion criteria: the study included patients not younger than 18 years old, undergoing cardiac surgery with CPB lasting up to 95 minutes (coronary bypass surgery, valve replacement), without signs of end-stage renal disease. Using nonparametric correlation analysis, we evaluated the effect on the development of acute kidney injury (AKI) of the following extracorporeal circulation factors: duration of CPB, aortic cross-clamp, mean arterial pressure (MAP), cardiac index (CI), perfusion flow rate (PFR), transport, consumption, and oxygen extraction variables. The diagnosis of AKI was made on the basis of the KDIGO classification, the studied parameters were recorded initially (before the operation), 15 minutes after the start of general anesthesia, 30 minutes after the start of cardiopulmonary bypass and 15 minutes after the end of general anesthesia. RESULTS. The frequency of AKI in 24 hours after surgery was 56.3 % (58 cases): including stage 1 in 37 (35.9 %), stage 2 in 17 (16.5 %) , stage 3 – in 4 (3.9 %) patients. In the 48th hour of the postoperative period, signs of AKI regressed and were presented in only 26 people (25.2 %), including the stage 1 in 18 (17.5 %), the stage 2 – in 5 (4.8 %), stage 3 – in 3 (2.9 %). Among the risk factors for AKI in cardiac surgery with CPB, the main effect of the anemia was revealed, especially a decrease in hemoglobin levels of less than 90 g / l and hematocrit of less than 25 %. CONCLUSION. Hemodilution below the "threshold" values of hemoglobin and hematocrit during the CPB provoke acute kidney injury in patients undergoing open-heart surgery.

Thromboelastometry and a hemostasis management system are most beneficial for guiding hemostatic therapy in cardiac surgery patients with a EuroSCORE II of ≥1.83%: a randomized controlled two-step trial.

We evaluated the efficacy of hemostatic therapy based on point-of-care (POC) testing in patients undergoing cardiac surgery. This was a single-institution, prospective, randomized, double-blinded study. In step 1, 90 patients scheduled for elective cardiac surgery underwent complete blood count and fibrinogen measurements at baseline, after cardiopulmonary bypass (CPB) initiation (CPB start), just after CPB end, and in the intensive care unit (ICU). In step 2, 72 patients scheduled for elective cardiac surgery underwent conventional laboratory coagulation tests (control group) or POC coagulation tests (POC group). Transfusions were prepared using the fibrinogen and platelet values at mainly "CPB start" for the control group, and using the ROTEM values at mainly "CPB end" for the POC group. Consequently, the step 2 patients were divided into high- and low-risk subgroups based on the EuroSCORE II by logistic regression analysis; transfusion data and bleeding volumes were compared between the control and POC groups within the high- and low-risk subgroups. In step 1, all blood components were significantly decreased at CPB start compared with baseline, and platelet and fibrinogen levels remained almost constant from CPB start to end. In step 2, the transfusion rates and perioperative bleeding volumes did not significantly differ between the control and POC groups. Subgroup analysis suggested that only the high-risk subgroup significantly differed regarding perioperative red blood cell transfusion and total bleeding volume in the ICU. POC testing is beneficial for cardiac surgery patients with a EuroSCORE II of ≥1.83%.

Predictors of Increased Lactate in Neonatal Cardiac Surgery: The Impact of Cardiopulmonary Bypass

Hyperlactatemia develops intraoperatively during cardiac surgery and is associated with postoperative mortality. This study aimed to determine the factors that lead to an increase in lactate during cardiopulmonary bypass (CPB) in neonates undergoing cardiac surgery. Retrospective study from July 2015 to December 2018. Academic tertiary children's hospital. The study comprised 376 neonates. No interventions were performed. Lactate measurements at prebypass, upon initiation of CPB and before coming off CPB, last in the operating room, and first in the cardiac intensive care unit were collected. The changes in lactate levels were compared using the nonparametric Wilcoxon signed rank test for paired data. Univariate and multivariate median regression models of the change during CPB were determined. The cohort characteristics were male (60%), median age 5 days (range 1-30), and weight 3.2 kg (range 1.5-4.7). Most patients had a STAT score of 4 (45%) or 5 (23%). Significant increases in lactate were observed from pre-CPB to start of CPB (p < 0.001) and from start to end of CPB (p < 0.001). In the multivariate regression analysis, duration of circulatory arrest (coefficient = 1.216; 95% confidence interval [CI] 0.754-1.678; p < 0.001), duration of mean arterial pressure < 25 mmHg (coefficient = 0.423; 95% CI 0.196-to- 0.651; p < 0.001), and duration of mean arterial pressure between 35 and 39 mmHg (coefficient = -0.246; 95% CI -0.397 to -0.095; p = 0.001) were identified as significant independent predictors of the lactate change per 30- minutes duration. These results emphasized the importance of blood pressure management during CPB and the importance of the duration of circulatory arrest.

P0115EFFECT OF CARDIOPULMONARY BYPASS ON THE DEVELOPMENT OF ACUTE KIDNEY INJURY AFTER OPEN-HEARD SURGERY

Abstract Background and Aims Assessment of factors associated with cardiopulmonary bypass (CPB) in acute renal dysfunction in patients in the early postoperative period after cardiac surgery. Method Monocentric observational study in patients (n = 97) who underwent elective open-heart cardiac surgery (coronary artery bypass grafting -50.44%, aortic valve prosthetics - 31.04%, mitral valve prosthetics - 12.61%) using cardiopulmonary bypass. Inclusion criteria: the study included patients not younger than 18 years old, undergoing cardiac surgery with CPB lasting up to 95 minutes (coronary bypass surgery, valve replacement), without signs of end-stage chronic kidney disease (CKD). Using nonparametric correlation analysis, we evaluated the effect on the development of acute kidney injury (AKI) of the following extracorporeal circulation factors: duration of CPB, aortic cross-clamp, mean arterial pressure (MAP), cardiac index (CI), perfusion flow rate (PFR), transport, consumption and oxygen extraction variables. The diagnosis of AKI was made on the basis of the KDIGO classification, the studied parameters were recorded initially (before the operation), 15 minutes after the start of general anesthesia, 30 minutes after the start of cardiopulmonary bypass and 15 minutes after the end of general anesthesia. Results The frequency of AKI in 24 hours after surgery was 56.3% (58 cases): including stage 1 in 37 (35.9%), stage 2 in 17 (16.5%), stage 3 - in 4 (3.9%) patients. In the 48th hour of the postoperative period signs of AKI regressed, and were presented in only 26 people (25.2%), including the stage 1 in 18 (17.5%), the stage 2 - in 5 (4.8%), stage 3 - in 3 (2.9%). Among the risk factors for AKI in cardiac surgery with CPB, the main effect of of the anemia was revealed, especially a decrease in hemoglobin levels of less than 90 g / l and hematocrit of less than 25%. Conclusion Hemodilution below the "threshold" values of hemoglobin and hematocrit during the CPB provoke acute kidney injury in patients undergoing open-heart surgery.

Levosimendan Versus Milrinone for Inotropic Support in Pediatric Cardiac Surgery: Results From a Randomized Trial

The present study aimed to determine the differential effects of intraoperative administration of milrinone versus levosimendan on myocardial function after pediatric cardiac surgery. Transthoracic echocardiography was used for myocardial function evaluation using biventricular longitudinal strain with 2-dimensional speckle tracking echocardiography in addition to conventional echocardiographic variables. A secondary analysis of a randomized, prospective, double-blinded clinical drug trial. Two pediatric tertiary university hospitals. Infants between 1 and 12 months old diagnosed with ventricular septal defect, complete atrioventricular septal defect, or tetralogy of Fallot who were scheduled for corrective surgery with cardiopulmonary bypass. The patients were randomly assigned to receive an infusion of milrinone or levosimendan at the start of cardiopulmonary bypass and for 26 consecutive hours. Biventricular longitudinal strain and conventional echocardiographic variables were measured preoperatively, on the first postoperative morning, and before hospital discharge. The association between perioperative parameters and postoperative myocardial function also was investigated. Images were analyzed for left ventricular (n = 67) and right ventricular (n = 44) function. The day after surgery, left ventricular longitudinal strain deteriorated in both the milrinone and levosimendan groups (33% and 39%, respectively). The difference was not significant. The corresponding deterioration in right ventricular longitudinal strain was 42% and 50% (nonsignificant difference). For both groups, biventricular longitudinal strain approached preoperative values at hospital discharge. Preoperative N-terminal pro-brain natriuretic peptide could predict the left ventricular strain on postoperative day 1 (p = 0.014). Levosimendan was comparable with milrinone for left and right ventricular inotropic support in pediatric cardiac surgery.

Targeting of cell-free DNA by DNase I diminishes endothelial dysfunction and inflammation in a rat model of cardiopulmonary bypass

The use of cardiopulmonary bypass (CPB) results in the activation of leukocytes, release of neutrophil extracellular traps (NETs) and severe inflammation. We hypothesize that targeting of circulating cell-free DNA (cfDNA) by DNases might represent a feasible therapeutic strategy to limit CPB-associated side effects. Male Wistar rats (n = 24) underwent CPB with deep hypothermic circulatory arrest (DHCA) and were divided into 3 groups: control (group 1), one i.v. bolus DNase I before CPB start (group 2) and a second DNase I dose before reperfusion (group 3). We found a positive correlation between plasma cfDNA/NETs levels and compromised endothelial vasorelaxation after CPB. DNase I administration significantly diminished plasma cfDNA/NETs levels. Further, a dose-dependent improvement in endothelial function accompanied by significant reduction of circulating intercellular adhesion molecule (ICAM)-1 was observed. Rats of group 3 had significantly reduced plasma IL-6 levels and downregulated expression of adhesion molecules resulting in impaired leukocyte extravasation and reduced MPO activity in lungs. Mechanistically, digestion of NETs by DNase I significantly diminished NETs-dependent upregulation of adhesion molecules in human endothelial cells. Altogether, systemic DNase I administration during CPB efficiently reduced cfDNA/NETs-mediated endothelial dysfunction and inflammation and might represents a promising therapeutic strategy for clinical practice.

The Effect of Levosimendan Versus Milrinone on the Occurrence Rate of Acute Kidney Injury Following Congenital Heart Surgery in Infants: A Randomized Clinical Trial.

It has been shown that, in contrast to other inotropic agents, levosimendan improves glomerular filtration rate after adult cardiac surgery. The aim of this study was to investigate the efficacy of levosimendan, compared with milrinone, in preventing acute kidney dysfunction in infants after open-heart surgery with cardiopulmonary bypass. Two-center, double-blinded, prospective, randomized clinical trial. The study was performed in two tertiary pediatric centers, one in Sweden (Gothenburg) and one in Finland (Helsinki). Infants between 1 and 12 months old, diagnosed with Tetralogy of Fallot, complete atrioventricular septal defect or nonrestrictive ventricular septal defect, undergoing total corrective cardiac surgery with cardiopulmonary bypass. Seventy-two infants were randomized to receive a perioperative infusion of levosimendan (0.1 µg/kg/min) or milrinone (0.4 µg/kg/min). The infusion was initiated at the start of cardiopulmonary bypass and continued for 26 hours. The primary outcome variable was the absolute value of serum creatinine data on postoperative day 1. Secondary outcomes included the following: 1) acute kidney injury according to the serum creatinine criteria of the Kidney Diseases: Improving Global Outcomes; 2) acute kidney injury with serum creatinine corrected for fluid balance; 3) plasma neutrophil gelatinase-associated lipocalin; 4) cystatin C; 5) urea; 6) lactate; 7) hemodynamic variables; 8) use of diuretics in the PICU; 9) need of dialysis; 10) length of ventilator therapy; and 11) length of PICU stays. There was no significant difference in postoperative serum creatinine between the treatment groups over time (p = 0.65). The occurrence rate of acute kidney injury within 48 hours was 46.9% in the levosimendan group and 39.5% in the milrinone group (p = 0.70). There were no significant differences in other secondary outcome variables between the groups. Levosimendan compared with milrinone did not reduce the occurrence rate of acute kidney injury in infants after total corrective heart surgery for atrioventricular septal defect, ventricular septal defect, or Tetralogy of Fallot.

The use of mannitol in cardiopulmonary bypass prime solution-Prospective randomized double-blind clinical trial.

BackgroundThe optimal prime solution for the cardiopulmonary bypass (CPB) circuit in adult cardiac surgery has not yet been defined. Mannitol is widely used in the priming solution for CPB despite the fact that there is no clear consensus on the role of mannitol in cardiac surgery. The aim of this study was to investigate the effect of mannitol in the CPB prime solution.MethodsThis prospective, randomized, double‐blind study included 40 patients with normal cardiac and renal functions, who underwent coronary artery bypass grafting. One group received a prime based on Ringer's acetate (n = 20), and the other a prime consisting of Ringer's acetate with 200 mL mannitol (n = 20). Changes in osmolality, acid‐base status, electrolytes, and renal‐related parameters were monitored.ResultsNo significant differences were found in osmolality between the Ringer's acetate group and the mannitol group at any time. The mannitol group showed a pronounced decrease in sodium, from 138.7 ± 2.8 mmol/L at anaesthesia onset, to 133.9 ± 2.6 mmol/L after the start of CPB (P < .001). No differences were seen in the renal parameters between the groups, apart from a short‐term effect of mannitol on peroperative urine production (P = .003).ConclusionWe observed no effects on osmolality of a prime solution containing mannitol compared to Ringer's acetate‐based prime in patients with normal cardiac and renal function. The use of mannitol in the prime resulted in a short‐term, significant decrease in sodium level.

Evaluation of attention, perception, and stress levels of clinical cardiovascular perfusionists during cardiac operations: a pilot study.

Performing cardiopulmonary bypass is a complex task which involves evaluating visual input from patient monitors and technical parameters displayed at the heart-lung machine console as well as reacting to other sensory input. Only few studies are available concerning the competency requirements for clinical cardiovascular perfusionists, including attention, perception, and coping with mental stress. This study aims at evaluating attention, perception, and stress levels of clinical cardiovascular perfusionists during cardiopulmonary bypass. Nine clinical cardiovascular perfusionists voluntarily offered to participate in the study. Participants were asked to wear Tobii 2 eye-tracking glasses throughout the procedures. Specific time points were analyzed (cardiopulmonary bypass on, initial cardioplegia delivery, steady state, cross-clamp off, and weaning from cardiopulmonary bypass). Data acquisition was supplemented by participants' self-evaluation regarding their stress levels and by National Aeronautics and Space Administration Task Load Index (NASA TLX) questionnaires. Seven datasets were sufficient to be evaluated. The clinical cardiovascular perfusionists' professional experience ranged from 0.5 to 24 years. Evaluation of eye-tracking data revealed large variations in areas of interest hits, fixation, and dwell times. Across all phases, the venous reservoir, mean arterial pressure, arterial pump display, cardioplegia control, and data management system received the highest levels of attention. Pupil diameter measurements increased at start of cardiopulmonary bypass, cardioplegia delivery, and weaning off, but returned to base level during steady state. Clinical cardiovascular perfusionists' self-evaluation showed that subjective stress level was highest at the start and the end of the procedure. NASA TLX questionnaires revealed medium-to-high mental and temporal workloads, but low physical workloads. Performance, effort, and frustration indices showed medium workloads. During cardiopulmonary bypass, perfusionists are subjected to stress. Peak stress levels were highest during start and end of cardiopulmonary bypass. Furthermore, visual attention and perception varied between the operative phases. Further studies are indicated to evaluate the design of heart-lung machines and stress-coping strategies during cardiopulmonary bypass.

Impact of Cardiopulmonary Bypass Flow on Renal Oxygenation in Patients Undergoing Cardiac Operations

Cardiac surgery with cardiopulmonary bypass (CPB) is associated with acute kidney injury, and the risk increases with low oxygen delivery during CPB. We hypothesized that renal oxygenation could be improved at higher than normal CPB flow rates. After ethical approval and informed consent, 17 patients with normal serum creatinine undergoing normothermic CPB were included and received pulmonary artery and renal vein catheters after anesthesia induction for measurements of systemic and renal variables. Renal oxygen extraction, a direct measure of the renal oxygen delivery/renal oxygen consumption ratio, and renal filtration fraction were measured, the latter by renal extraction of 51chromium-ethylenediaminetetraacetic acid. After start of CPB and aortic cross-clamp, the pump flow rate was randomly varied between 2.4, 2.7, and 3.0 L · min-1 · m-2, and measurements were made after 10 minutes at each flow rate. Renal oxygen extraction increased by 30% at a flow rate of 2.4 L · min-1 · m-2 versus pre-CPB (p < 0.05). At a flow rate of 2.7 and 3.0 L · min-1 · m-2, Renal oxygen extraction was 12% (p < 0.05) and 23% (p < 0.01) lower, respectively, compared with 2.4 L · min-1 · m-2. This corresponds to a 14% and 30% improvement, respectively, of the renal oxygen supply/demand relationship. Filtration fraction was not affected by changes in flow rate, indicating that the glomerular filtration rate increased in proportion to the increase in renal perfusion. The impaired renal oxygenation seen during CPB is ameliorated by an increase in CPB flow rate. Thus, one way to protect the kidneys during CPB could be to use a higher flow rate than the one traditionally used.

Early intraoperative iron-binding proteins are associated with acute kidney injury after cardiac surgery

ObjectivesIron regulation is an important modifier of renal ischemia–reperfusion injury, but the role of iron-binding proteins during cardiopulmonary bypass remains unclear. The goal was to characterize iron-binding proteins throughout ischemia–reperfusion injury to determine their association with acute kidney injury development. MethodsA prospective observational cohort of adult patients who underwent cardiac surgery (n = 301) was obtained, and acute kidney injury was defined by Kidney Disease Improving Global Outcomes. Serum ferritin, transferrin saturation, and urine hepcidin-25 were measured. ResultsIntraoperative serum ferritin was lower at the start of cardiopulmonary bypass (P = .005) and 1-hour cardiopulmonary bypass (P = .001) in patients with acute kidney injury versus patients without acute kidney injury. Lower serum ferritin and higher transferrin saturation at 1-hour cardiopulmonary bypass were independent predictors of acute kidney injury (serum ferritin odds ratio, 0.66; 95% confidence interval [CI], 0.48-0.91; transferrin saturation odds ratio, 1.26; 95% CI, 1.02-1.55) and improved model discrimination (area under the curve [AUC], 0.76; 95% CI, 0.67-0.85) compared with clinical prediction alone (AUC, 0.72; 95% CI, 0.62-0.81; ΔAUC and net reclassification index, P = .01). Lower ferritin, higher transferrin saturation at 1-hour cardiopulmonary bypass, and lower urine hepcidin-25 at postoperative day 1 were also independent predictors for acute kidney injury development, and this model demonstrated an AUC of 0.80 (0.72-0.87), which was superior to clinical prediction (ΔAUC P = .002, integrated discrimination improvement and net reclassification index P = .003). ConclusionsOur findings suggest that lower levels of intraoperative iron-binding proteins may reflect an impaired capacity to rapidly handle catalytic iron released during cardiopulmonary bypass, leading to kidney injury. These data highlight the importance of iron homeostasis in human ischemia–reperfusion injury and suggest it is a potentially modifiable risk during cardiac surgery. Intraoperative detection of incipient acute kidney injury may be feasible and could be used as an enrichment strategy for clinical trials.

Effect of ulinastatin on perioperative glycocalyx and lung function in patients undergoing mitral valve replacement surgery

To explore the effect of ulinastatin on perioperative glycocalyx and lung function in patients undergoing mitral valve replacement surgery. Methods: Fourty patients, undergoing mitral valve replacement, were randomly allocated into a control group and an ulinastatin group, which were administrated 50 mL normal saline or 2×104 U/kg ulinastatin at the beginning of cardiopulmonary bypass (CPB), respectively. The radical artery blood was collected at 4 time points: After induction of anesthesia (T0), at 10 min after the start of CPB (T1), 1 h after the end of CPB (T2), and 8 h after operation. The concentration of syndecan-1 and TNF-α in blood was measured. Moreover, the blood gas analysis was preformed and the oxygen index (OI) and difference in alveolar arterial oxygen partial pressure (PA-aO2) were calculated at T0, T2, and T3. Results: There were no significant difference between the 2 groups in OI, PA-aO2, and the concentration of syndecan-1 and TNF-α at T0 (P>0.05). The concentration of syndecan-1 and TNF-α was significantly increased at T1 and T2 in the 2 groups, and reached peak at T2. Compared with the control group, the concentration of syndecan-1 and TNF-α was decreased in the ulinastatin group at T1, T2, and T3 (P<0.05). Compared with T0, OI was lower and PA-aO2 was higher at T2 and T3 in both groups, but the 2 indexes were improved in the ulinastatin group compared with those in the control group (P<0.05). Conclusion: Ulinastatin can improve the post-operative pulmonary ventilation function in patients with mitral valve replacement. The mechanism may be associated with the inhibition of TNF-α release and the reduction of glycocalyx shedding induced by ulinastatin.

Cardiopulmonary-Bypass Glial Fibrillary Acidic Protein Correlates With Neurocognitive Skills

Neurocognitive deficits at school starting age may affect as many as 50% of children who underwent cardiac surgery for complex congenital heart disease (CHD). The aim of this study was to identify which phases of cardiopulmonary bypass (CPB) are associated with an increased risk of impaired neurodevelopmental skills in children with complex CHD. This was assessed by means of glial fibrillary acidic protein (GFAP) plasma levels during CPB for CHD surgery, as a marker of neurologic insult. We correlated GFAP levels with clinical parameters and neurodevelopmental outcome. We studied 45 children undergoing surgery for complex CHD. We measured plasma GFAP levels by enzyme-linked immunosorbent assay at the following steps: anesthesia induction, CPB start, end of hypothermia, end of rewarming, and end of CPB. Neurologic assessment and Vineland Adaptive Behavior Scales (VABS-I) were administered to patients at least 18 months after surgery. GFAP was undetectable before surgery and it peaked at the end of hypothermia or rewarming. Multiple regression analyses showed that GFAP peak level and preoperative neurologic comorbidity were significant independent predictors of neurologic impairment, as showed by VABS-I communication domain intelligence quotient (IQ). Receiver operating characteristic curve showed that the model was highly significant. Impaired neurodevelopment was associated with increase of GFAP plasma levels during cardiac surgery in infants. The identification of the neurologic high-risk phases of CPB run could support the application of new neuroprotective strategies for CHD repair.

Correlation between regional tissue perfusion saturation and lactate level during cardiopulmonary bypass.

BackgroundCardiopulmonary bypass (CPB) can cause systemic hypoperfusion, which remains undetected by routine monitoring of physiological parameters. Noninvasive tissue perfusion monitoring offers a clinical benefit by detecting low systemic perfusion. In this study, we tried to evaluate whether regional tissue perfusion saturation reflects systemic hypoperfusion during CPB.MethodsThis retrospective study included 29 patients with American Society of Anesthesiologists physical status II–III, who required cardiac surgery with CPB. We evaluated the correlations of serum lactate and delivery oxygen with organ perfusion values of peripheral tissue oxygen saturation and cerebral oxygen saturation. Data were recorded at different stages of CPB: T1 (pre-CPB), T2 (cooling), T3 (hypothermia), T4 (rewarming), and T5 (post-CPB).ResultsLactate levels were elevated after CPB and up to weaning (P < 0.05). The levels of peripheral and tissue oxygen saturation decreased after the start of CPB (P < 0.05). Lactate levels were negatively correlated with peripheral tissue oxygen saturation levels at T4 (R = −0.384) and T5 (R = −0.370) and positively correlated with cerebral oxygen saturation at T3 (R = 0.445). Additionally, delivery oxygen was positively correlated with peripheral tissue oxygen saturation at T4 (R = 0.466).ConclusionsIn this study, we demonstrated that peripheral tissue oxygen saturation can be a reliable tool for monitoring systemic hypoperfusion during CPB period. We also believe that peripheral tissue oxygen saturation is a valuable marker for detecting early stages of hypoperfusion during cardiac surgery.

Relationship between antithrombin III genetic polymorphism and individual variation in anticoagulant effect of heparin in patients of different nationalities

Objective To evaluate the relationship between antithrombin Ⅲ(ATⅢ)genetic polymorphism and individual variation in anticoagulant effect of heparin in the patients of different nationalities. Methods Sixty patients of Uighur nationality and 60 patients of Han nationality, aged 18-64 yr, with body mass index of 21-25 kg/m2, of American Society of Anesthesiologists physical statusⅠ-Ⅲ, undergoing elective cardiac surgery under cardiopulmonary bypass, were divided into Uighur group and Han group, respectively.ATⅢ gene polymorphism was detected by polymerase chain reaction(A/G was heterozygous, A/A and G/G were homozygous). Heparin sodium was intravenously injected at 5 min before the start of cardiopulmonary bypass with an amount of ACT ≥ 480 s. The amount of heparin and protamine, intraoperative blood transfusion and postoperative 24 h drainage(pericardium, mediastinum/thoracic cavity)were recorded.Activated partial thromboplastin time and prothrombin time were measured at 10 min before operation and 24 h after operation. Results Compared with Han group, the amount of heparin, ratio of protamine to heparin for heparin neutralization and requirement for intraoperative blood transfusion were significantly decreased, the postoperative drainage volume was decreased, activated partial thromboplastin time was shortened at 24 h after operation, the frequency of A/A genotype was increased and the frequency of G/G genotype was decreased at ATⅢ gene single-nucleotide polymorphism sites rs5877 and rs5878, and the minimum allele(A>G)frequency was increased in Uighur group(P<0.05). Conclusion ATⅢ gene polymorphism may be one of the mechanisms underlying individual variation in anticoagulant effect of heparin between the patients of Uighur nationality and Han nationality. Key words: Antithrombin Ⅲ; Polymorphism, single nucleotide; Heparin; Ethnic groups