Conventional hemofiltration during cardiopulmonary bypass increases the serum lactate level in adult cardiac surgery

Association of Weight-indexed Conventional Ultrafiltration Volume with Post-operative Lactate in Patients Undergoing Cardiopulmonary Bypass

Background

Conventional ultrafiltration (CUF) during cardiopulmonary bypass (CPB) is utilized to minimize hemodilution. However, removing high volumes leads to tissue hypoperfusion by activating the anaerobic glycolysis pathways. This study aimed to determine the association between weight-indexed CUF volumes and lactate in patients who underwent coronary artery bypass grafting (CABG).

Methods

In this single-center retrospective study, 641 CABG patients, who were referred to Al-Zahra Hospital (Shiraz, Iran) and underwent CPB, during 2019-2021, were recruited. Peri-operative parameters were extracted from the patient's records. The patients with non-elective status, pre-existing liver and renal diseases, ejection fraction<35%, and repeated sternotomy were excluded from the study. An increase in post-operative lactate level≥4 mmol/L after 6 hours was defined as hyperlactatemia (HL). To predict HL, univariable and multiple logistic regression modeling, while controlling confounding factors, were employed.

Results

The patients' mean age was 58.8±11.1 years, and 39.2% were women. The incidence of HL was 14.5% (93 patients). There was a significant association between weight-indexed CUF volume and HL. The volume removed in the HL patients was almost doubled (43.37±11.32 vs. 21.41±8.15 mL/Kg, P<0.001), and the higher the weight-indexed CUF volume, the more likely to develop an HL at a rate of 1.38 (Odds ratio=1.38 [1.27-1.49], 95% CI, P<0.001). Furthermore, the multiple logistic regression model showed that HL was associated with the lowest mean arterial pressure (MAP) during CPB.

Conclusion

A higher volume of ultrafiltration was associated with increased post-operative serum lactate levels.

Practical training concept for perfusionists at the heart and diabetes center Nordrhein-Westfalen

BACKGROUND

Increasing regulations and requirements of advisory bodies, in particular the Joint Federal Committee and the Medical Service of the health insurance funds, make it necessary to employ only demonstrably well-trained perfusionists. The minimum requirement for this staff is EBCP certification. Currently there is limited availability of such specialists on the German market. Therefore, the qualification of young people in this area is of central importance. The aim of this paper is to strengthen the training of perfusionists at our centre, to standardise the process and to provide the respective student with a "roadmap" to their internship.

MATERIAL & METHODS

The structure is based on a rough division of the 24 weeks of internship. This is described in detail in the following and is backed up with the learning objectives for the respective time periods.

RESULTS

At our centre, practical training has been standardized and clear responsibilities have been defined. Furthermore, as a centre of maximum care in the field of cardiac surgery, we can offer students the necessary number of perfusions in just six months to meet the requirements of the ECBP for practical training. According to this concept, 20 perfusionists have been successfully trained in the last 8 years. All of them have passed the exams and have been certified according to EBCP.

CONCLUSION

The aim of the practical semester is for the student to be in a position at the end of the semester to independently supervise simple cardiac surgery procedures with the aid of the Extra- Corporal Circulation (ECC) and to carry this out in accordance with the currently valid guidelines and directives (1-8) and the departmental procedural instructions based on them. Great emphasis is placed to the students becoming aware of their competence to act, knowing their limits and being able to assess when these limits have been reached and the involvement of experienced colleagues is necessary to ensure patient safety.

Is ultrafiltration volume a predictor of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass?

INTRODUCTION

Intraoperative ultrafiltration (UF) is a procedure used during cardiopulmonary bypass (CPB) to reduce haemodilution and prevent excessive blood transfusion. However, the effect of UF volume on acute kidney injury (AKI) is not well established, and the results are conflicting. Additionally, there are no set indications for applying UF during CPB.

METHODS

This retrospective study analysed 641 patients who underwent coronary artery bypass graft (CABG) surgery with CPB. Perioperative parameters were extracted from the patients' records, and the UF volume was recorded. Acute Kidney Injury Network classification was used to define AKI. Univariable and multivariable logistic regression models were used to predict AKI while controlling for confounding factors.

RESULTS

The study enrolled patients with a mean age of 58.8 ± 11.1 years, 39.2% of whom were female. AKI occurred in 22.5% of patients, with 16.1% (103) experiencing stage I and 6.4% (41) experiencing stage II. The results showed a significant association between UF volume and the risk of developing AKI, with higher UF volumes associated with a higher risk of AKI. In the multivariable analysis, the other predictors of AKI included age, lowest mean arterial pressure (MAP), and red blood cell (RBC) transfusion during CPB.

CONCLUSION

The predictors of postoperative AKI in coronary CABG patients were the volume of UF, age, MAP, and blood transfusion during CPB.

Factors associated with increased lactate levels in cardiac surgeries: scoping review

OBJECTIVES

to map the factors associated with increased lactate levels in the postoperative period of cardiac surgery using extracorporeal circulation.

METHODS

this is a scoping review carried out in December 2022, across ten data sources. It was prepared in accordance with the recommendations of the Joanna Briggs Institute and the Preferred Reporting Items for Systematic Reviews and Meta Analyses Extension for Scoping Reviews checklist.

RESULTS

the most recurrent findings in studies regarding the factors responsible for the increase in lactate were: tissue hypoperfusion, cardiopulmonary bypass time and use of vasoactive drugs. In 95% of studies, increased lactate was related to increased patient mortality.

CONCLUSIONS

discussing the causes of possible complications in cardiac surgery patients is important for preparing the team and preventing complications, in addition to ensuring quality recovery.

PERSUADE Survey-PERioperative AnestheSia and Intensive Care Management of Left VentricUlar Assist DevicE Implantation in Europe and the United States

OBJECTIVE

To comprehensively assess relevant institutional variations in anesthesia and intensive care management during left ventricular assist device (LVAD) implantation.

DESIGN

The authors used a prospective data analysis.

SETTING

This was an online survey.

PARTICIPANTS

Participants were from LVAD centers in Europe and the US.

INTERVENTIONS

After investigating initial interest, 91 of 202 European and 93 of 195 US centers received a link to the survey targeting institutional organization and experience, perioperative hemodynamic monitoring, medical management, and postoperative intensive care aspects.

MEASUREMENTS AND MAIN RESULTS

The survey was completed by 73 (36.1%) European and 60 (30.8%) US centers. Although most LVAD implantations were performed in university hospitals (>5 years of experience), significant differences were observed in the composition of the preoperative multidisciplinary team and provision of intraoperative care. No significant differences in monitoring or induction agents were observed. Propofol was used more often for maintenance in Europe (p < 0.001). The choice for inotropes changed significantly from preoperatively (more levosimendan in Europe) to intraoperatively (more use of epinephrine in both Europe and the US). The use of quantitative methods for defining right ventricular (RV) function was reported more often from European centers than from US centers (p < 0.05). Temporary mechanical circulatory support for the treatment of RV failure was more often used in Europe. Nitric oxide appeared to play a major role only intraoperatively. There were no significant differences in early postoperative complications reported from European versus US centers.

CONCLUSIONS

Although the perioperative practice of care for patients undergoing LVAD implantation differs in several aspects between Europe and the US, there were no perceived differences in early postoperative complications.

Association of Conventional Ultrafiltration on Postoperative Pulmonary Complications

BACKGROUND

Postoperative pulmonary complications increase mortality after cardiac surgery. Conventional ultrafiltration may reduce pulmonary complications by removing mediators of bypass-induced inflammation and countering hemodilution. We tested the primary hypothesis that conventional ultrafiltration reduces postoperative pulmonary complications, and secondarily, improves early pulmonary function assessed by the ratio of PaO2 to fractional inspired oxygen concentration.

METHODS

This retrospective analysis compared the incidence of postoperative pulmonary complications in adult patients who underwent cardiac surgery, with and without the use of conventional ultrafiltration, by using logistic regression with adjustment for confounding variables. The primary outcome was a composite of reintubation, prolonged ventilation, pneumonia, or pleural effusion. Secondarily, we examined early postoperative lung function using a quantile regression model. We also explored whether red blood cell transfusion differed between groups.

RESULTS

Of 8026 patients, 1043 (13%) received conventional ultrafiltration. After adjustment for confounding variables, the incidence of the composite primary outcome was higher in the conventional ultrafiltration group (12.1% vs 9.9%; P = .03), with an estimated odds ratio of 1.25 (95% CI, 1.02-1.53; P = .03). The median (quantiles) PaO2-to-fractional inspired oxygen concentration ratio was 373 (303-433) vs 368 (303-428), with the estimated adjusted difference in medians of 5 (95% CI, -5.9 to 16; P = .37). The estimated odds ratio of intraoperative transfusion was 1.38 (95% CI, 1.19-1.60; P < .0001) and for postoperative transfusion was 1.30 (95% CI, 1.14-1.49; P = .0001).

CONCLUSIONS

Use of conventional ultrafiltration was not associated with a reduction in the composite of postoperative pulmonary complications or improved early pulmonary function. We found no evidence of benefit from use of conventional ultrafiltration during cardiac surgery.

Does severe hyperlactatemia during cardiopulmonary bypass predict a worse outcome?

INTRODUCTION

The aim of the current study was to evaluate the impact of increased blood lactate levels during cardiopulmonary bypass (CPB) on immediate results in patients who underwent open heart surgery.

MATERIALS AND METHODS

We performed a retrospective single-center study on 1290 patients. Adult cardiac surgical patients who underwent valve surgery, coronary artery bypass graft, combined procedure, adult congenital anomalies and aortic surgery were enrolled. Patients with associated comorbidities such as liver dysfunction, hemodynamic instability before surgery were excluded. Arterial blood lactate concentration was measured immediately after weaning from CPB and evaluated together with clinical data and outcomes including in hospital mortality. Patients were classified into 3 groups according to their peak arterial lactate level: group I [normal lactatemia, lactate ˂ 2 mmol/l (n = 749)], group II [mild hyperlactatemia, lactate 2-5 mmol/l (n = 489)], group III [severe hyperlactatemia, lactate ˃ 5 mmol/l (n = 52)].

RESULTS

When comparing outcomes across the 3 groups, severe hyperlactatemia was correlated with worse outcomes including higher in-hospital mortality, low output cardiac syndrome, postoperative renal insufficiency, myocardial infarction, red blood cell transfusion (RBC) transfusion, prolonged mechanical ventilation and longer intensive care unit (ICU) stay hours.

CONCLUSION

Blood lactate level above 5 mmol/l and more during CPB is associated with higher in-hospital mortality rate and postoperative complications. More attention must be given to correct the common abnormalities conditions inherent of CPB in order to conduct adequate tissue perfusion and reduce the risk of hyperlactatemia.

Continuous ultrafiltration during extracorporeal circulation and its effect on lactatemia: A randomized controlled trial

Introduction

Hyperlactatemia occurs during or after extracorporeal circulation in the form of lactic acidosis, increasing the risk of postoperative complications and the mortality rate. The aim of this study was to evaluate whether continuous high-volume hemofiltration with volume replacement through a polyethersulfone filter during the extracorporeal circulation procedure decreases postoperative lactatemia and its consequences.

Materials and methods

This was a randomized controlled trial. Patients were randomly divided into two groups of 32: with or without continuous high-volume hemofiltration through a polyethersulfone membrane. Five patients were excluded from each group during the study period. The sociodemographic characteristics, filter effects, and blood lactate levels at different times during the procedure were evaluated. Secondary endpoints were studied, such as the reduction in the intubation time and time spent in ICU.

Results

Lactatemia measurements performed during the preoperative and intraoperative phases were not significantly different between the two groups. However, the blood lactate levels in the postoperative period and at 24 hours in the intensive care unit showed a significant reduction and a possible clinical benefit in the hemofiltered group. Following extracorporeal circulation, the mean lactate level was higher (difference: 0.77 mmol/L; CI 0.95: 0.01–1.53) in the nonhemofiltered group than in the hemofiltered group (p<0.05). This effect was greater at 24 hours (p = 0.019) in the nonhemofiltered group (difference: 1.06 mmol/L; CI 0.95: 0.18–1.93) than in the hemofiltered group. The reduction of lactatemia is associated with a reduction of inflammatory mediators and intubation time, with an improvement in liver function.

Conclusions

The use and control of continuous high-volume hemofiltration through a polyethersulfone membrane during heart-lung surgery could potencially prevent postoperative complications. The reduction of lactatemia implied a reduction in intubation time, a decrease in morbidity and mortality in the intensive care unit and a shorter hospital stay.

Intraoperative Fluid Balance and Perioperative Outcomes After Aortic Valve Surgery

BACKGROUND

The effect of intraoperative fluid balance on postoperative acute kidney injury (AKI) in cardiac surgical patients is poorly defined.

METHODS

In this retrospective study of patients undergoing aortic valve replacement for aortic stenosis, the primary outcome of interest was postoperative AKI. Secondary outcomes were postoperative fluid balance, cardiac index, vasopressor use, hospital-free days, stroke, myocardial infarction, hospital readmission, and 30- and 90-day mortality.

RESULTS

A total of 2327 patients were analyzed. Positive intraoperative fluid balance was associated with lower odds of AKI; the lowest odds were in the 20- to 39-mL/kg group (odds ratio, 0.56; 95% confidence interval, 0.38-0.81; P = .002). Positive intraoperative fluid balance was associated with a lower postoperative fluid balance. Increased ultrafiltration volume was associated with increased postoperative fluid resuscitation and vasopressor use. AKI was associated with increased 30- and 90-day mortality. Increased fluid balance was associated with increased odds of myocardial infarction and 30-day mortality. Increased ultrafiltration volume was associated with increased odds of 30- and 90-day mortality.

CONCLUSIONS

In patients who underwent aortic valve replacement for aortic stenosis, positive intraoperative fluid balance was associated with decreased odds of AKI. Patients developing AKI had increased 30- and 90-day mortality. Although the overall incidence was low, increased intraoperative fluid balance was associated with myocardial infarction and 30-day mortality, whereas increased ultrafiltration volume was associated with 30- and 90-day morality. Prospective studies are needed to better define proper intraoperative fluid management in patients undergoing cardiac surgery.

The effect of ultrafiltration on end-cardiopulmonary bypass hematocrit during cardiac surgery

OBJECTIVE

Ultrafiltration (UF) during cardiopulmonary bypass (CPB) is a well-accepted method for hemoconcentration to reduce excess fluid and increase hematocrit, platelet count and plasma constituents. The efficacy of this technique may confer specific benefit to certain patients presenting with acquired cardiac defects. The purpose of this study was to retrospectively evaluate the effect of UF on end-CPB hematocrit by cardiac surgical procedure type.

METHODS

A review of 73,506 cardiac procedures from a national registry (SCOPE) was conducted between April 2012 and October 2016 at 197 institutions. Cases included in this analysis were those completed without intraoperative red blood cell transfusion and where zero-balance UF was not used. The primary end point was the last hematocrit reading taken before the end of CPB, with a secondary end point of urine output during CPB. In order to isolate the effect of the UF volume removed, we controlled for a number of confounding factors, including: first hematocrit on CPB, total asanguineous volume, estimated circulating blood volume, CPB urine output, total volume of crystalloid cardioplegia, total volume of other asanguineous fluids administered by both perfusion and anesthesia, type of cardiac procedure, acuity, gender, age and total time on CPB. Descriptive statistics were calculated among five subgroups according to the UF volume removed: no volume removed and quartiles across the range of UF volume removed. The effect of UF volume on primary and secondary end points was modeled using ordinary least squares and restricted cubic splines in order to assess possible non-linearity in the effect of the UF volume while controlling for the above-named confounding factors. An interaction term was included in each model to account for possible differences by procedure type.

RESULTS

The study found a statistically significant non-linear pattern in the relationship between the UF volume removed and the last hematocrit on bypass (X² = 172.5, df=24, p<0.001). For most procedure types, UF was most effective at increasing the last hematocrit on CPB, from 1 mL to approximately 2.5 L, with continued improvements in hematocrit coming more slowly as the UF volume was increased above 2.5 L. There were statistically significant interactions between UF and procedure type (X² = 78.5, df=24, p<0.0001) as well as UF and starting hematocrit on CPB (X² = 234.0, df=4, p<0.0001). In a secondary end-point model, there was a statistically significant relationship between the ultrafiltration volume removed and urine output on bypass (X² = 598.9, df=28, p<0.001).

CONCLUSION

The use of UF during CPB resulted in significant increases in end-hematocrit, with the greatest benefit shown when volumes were under 2.5 L. We saw a positive linear benefit up to 2.5 L removed and, thereafter, in most procedures, the benefit leveled off. However, of note is markedly decreased urine output on bypass as the ultrafiltration volumes increase.