The Impact of Vacuum-Assisted Venous Drainage and Miniaturized Bypass Circuits on Blood Transfusion in Pediatric Cardiac Surgery

Carbon dioxide production index (VCO2i) predicts hyperlactatemia during cardiopulmonary bypass in ediatric carDiac surGery (pGDP- VCO2i): Study protocol for a nested case-control trial

BACKGROUND

Hyperlactatemia (HL) during cardiopulmonary bypass (CPB) is relatively frequent in infants and associates with increased morbidity and mortality. Studies on adults have shown that carbon dioxide production index (VCO2i) during CPB is linked to the occurrence of HL, with 'critical thresholds' for VCO2i reported to be 60 mL/min/m2. However, considering infants have a higher metabolic rate and lower tolerance to hypoxia, the critical threshold of VCO2i in infants cannot be replied to the existing adults' standards. The objective of this study is to investigate the association of VCO2i during CPB and HL, and explore the critical VCO2i threshold during CPB in infants.

METHODS

VCO2i predicts hyperlactatemia during cardiopulmonary bypass in pediatric cardiac surgery (pGDP-VCO2i) is a nested case-control study. A cohort of consecutive pediatric patients of less than 3 years of age, undergoing congenital cardiac surgeries between May 2021 and December 2023 in West China Hospital will be enrolled. The VCO2i levels of each patient will be recorded every 5 min during CPB. The primary outcome is the rate of HL. The infants will be divided into two groups based on the presence or not of HL. Pre- and intraoperative factors will be tested for independent association with HL. Then, we will make an analysis, and the critical value of VCO2i will be obtained. The postoperative outcome of patients with or without HL will be compared.

DISCUSSION

This will be the first trial to investigate the association of VCO2i during CPB and HL, and explore the critical VCO2i threshold during CPB in pediatrics. The results of this study are expected to lay a foundation for clinical application of goal-directed perfusion (GDP) management strategy, and optimize the perfusion strategy and improve the prognosis of pediatric patients undergoing cardiac surgery.

TRIAL REGISTRATION

Chictr.org.cn, ChiCTR2100044296 on 16 March 2021.

American Society of ExtraCorporeal Technology: Development of Standards and Guidelines for Pediatric and Congenital Perfusion Practice (2019)

The development of standards and guidelines by professional societies offers clinicians guidance toward providing evidence-based care. The ultimate goals of standards and guidelines are to standardize care and improve patient safety and outcomes while also minimizing risk. The American Society of ExtraCorporeal Technology (AmSECT) currently offers perfusionists several clinical resources, primarily the Standards and Guidelines for Perfusion Practice; however, no document exists specific to pediatric perfusion. Historically, the development of a pediatric-specific document has been limited by available scientific evidence because of smaller patient populations, sample sizes, and variable techniques among congenital perfusionists. In the current setting of evolving clinical practices and increasingly complex cardiac operations, a subcommittee of pediatric perfusionists developed the Standards and Guidelines for Pediatric and Congenital Perfusion Practice. The development process included a comprehensive literature review for supporting evidence to justify new recommendations or updates to the existing AmSECT Adult Standards and Guidelines document. Multiple revisions incorporating feedback from the community led to a finalized document accepted by the AmSECT member and made available electronically in May 2019. The Standards and Guidelines for Pediatric and Congenital Perfusion Practice is an essential tool for pediatric perfusionists, serves as the backbone for institutionally based protocols, promotes improved decision-making, and identifies opportunities for future research and collaboration with other disciplines. The purpose of this article is to summarize the process of development, the content, and recommended utilization of AmSECT's Standards and Guidelines for Pediatric and Congenital Perfusion Practice. AmSECT recommends adoption of the Standards and Guidelines for Pediatric and Congenital Perfusion Practice to reduce practice variation and enhance clinical safety.

American Society of ExtraCorporeal Technology: Development of Standards and Guidelines for Pediatric and Congenital Perfusion Practice (2019)

The development of standards and guidelines by professional societies offers clinicians guidance toward providing evidence-based care. The ultimate goals of standards and guidelines are to standardize care and improve patient safety and outcomes while also minimizing risk. The American Society of ExtraCorporeal Technology (AmSECT) currently offers perfusionists several clinical resources, primarily the Standards and Guidelines for Perfusion Practice; however, no document exists specific to pediatric perfusion. Historically, the development of a pediatric-specific document has been limited by available scientific evidence due to smaller patient populations, sample sizes, and variable techniques among congenital perfusionists. In the current setting of evolving clinical practices and increasingly complex cardiac operations, a subcommittee of pediatric perfusionists developed the Standards and Guidelines for Pediatric and Congenital Perfusion Practice. The development process included a comprehensive literature review for supporting evidence to justify new recommendations or updates to the existing AmSECT Adult Standards and Guidelines document. Multiple revisions incorporating feedback from the community led to a finalized document accepted by the AmSECT membership and made available electronically in May 2019. The Standards and Guidelines for Pediatric and Congenital Perfusion Practice is an essential tool for pediatric perfusionists and serves as the backbone for institutionally based protocols, promotes improved decision-making, and identifies opportunities for future research and collaboration with other disciplines. The purpose of this manuscript is to summarize the process of development, the content, and recommended utilization of AmSECT's Standards and Guidelines for Pediatric and Congenital Perfusion Practice.

Vacuum-assisted venous drainage in adult cardiac surgery: a propensity-matched study

OBJECTIVES

Conventional cardiopulmonary bypass with gravity drainage leads inevitably to haemodilution. Vacuum-assisted venous drainage (VAVD) utilizes negative pressure in the venous reservoir, allowing active drainage with a shortened venous line to reduce the priming volume. The goal of this study was to analyse the efficacy and safety of VAVD.

METHODS

Data on 19 687 patients (18 681 with gravity drainage and 1006 with VAVD) who underwent cardiac operations between 1 January 2015 and 31 January 2018 were retrospectively collected from a single centre. Propensity matching identified 1002 matched patient pairs with VAVD and gravity drainage for comparison of blood product transfusion rate, major morbidities and in-hospital mortality rates.

RESULTS

The blood transfusion rate of the VAVD group was lower than that of the gravity drainage group (28.1% vs 35% for red blood cells, 13% vs 18% for fresh frozen plasma and 0.1% vs 1.8% for platelets; P = 0.0009, 0.0020 and <0.0001, respectively). The mean difference (95% confidence interval) between the groups for red blood cells, fresh frozen plasma and platelets was -6.9% (-11.0% to -2.8%), -5.0% (-8.1% to -1.8%) and -1.7% (-2.5% to -0.9%), respectively. No difference was observed regarding the major morbidities of cerebrovascular accidents, acute kidney injury, hepatic failure and perioperative myocardial infarction and the in-hospital deaths between the 2 groups.

CONCLUSIONS

VAVD was associated with a reduction in blood product transfusions, and an increase in the risk of major morbidities and in-hospital deaths of the VAVD group was not observed.

Superior blood-saving effect and postoperative recovery of comprehensive blood-saving strategy in infants undergoing open heart surgery under cardiopulmonary bypass

BACKGROUND

Optimization of blood-saving strategies during open heart surgery in infants is still required. This study aimed to study a comprehensive blood-saving strategy during cardiopulmonary bypass (CPB) on postoperative recovery in low-weight infants undergoing open heart surgery.

METHODS

This was a prospective study of 86 consecutive infants (weighing <5 kg) with acyanotic congenital heart disease treated at the Tianjin Chest Hospital between March and December 2016, and randomized to the control (traditional routine CPB) and comprehensive blood-saving strategy groups. The primary endpoints were blood saving and clinical prognosis. The secondary endpoints were safety and laboratory indicators, prior to CPB (T1), after 30 minutes of CPB (T2), after modified ultrafiltration (T3), and postoperative 12 (T4), 24 (T5), 48 (T6), and 72 h (T7).

RESULTS

The total priming volume and banked red blood cells in the comprehensive strategy group were significantly lower than in the control group (P = .009 and P = .04, respectively). In the comprehensive strategy group, immediately after CPB, the amount of salvaged red blood cells exceeded the priming red blood cells by 40 ± 11 mL. Postoperatively, the comprehensive strategy group showed a significant decrease in the inotrope score (P = .03), ventilation time (P = .03), intensive care unit stay (P = .04), and hospital stay (P = .03) in comparison with the control group.

CONCLUSION

The comprehensive blood-saving strategies for CPB were associated with less blood use and favorable postoperative recovery in low-weight infants with congenital heart disease undergoing open heart surgery.

Strategies for blood conservation in pediatric cardiac surgery

Cardiac surgery accounts for the majority of blood transfusions in a hospital. Blood transfusion has been associated with complications and major adverse events after cardiac surgery. Compared to adults it is more difficult to avoid blood transfusion in children after cardiac surgery. This article takes into account the challenges and emphasizes on the various strategies that could be implemented, to conserve blood during pediatric cardiac surgery.

Evolution of membrane oxygenator technology for utilization during pediatric cardiopulmonary bypass

The development of the membrane oxygenator for pediatric cardiopulmonary bypass has been an incorporation of ideology and technological advancements with contributions by many investigators throughout the past two centuries. With the pursuit of this technological achievement, the ability to care for mankind in the areas of cardiac surgery has been made possible. Heart disease can affect anyone within the general population, but one such segment that it can affect from inception includes children. Currently, congenital heart defects are the most common birth defects nationally and worldwide. A large meta-analysis study from 1930 to 2010 was conducted in review of published medical literature totaling 114 papers with a study population of 24,091,867 live births, and divulged a staggering incidence of congenital heart disease involving 164,396 subjects with diverse cardiac illnesses. The prevalence of these diseases increased from 0.6 per 1,000 live births from 1930-1934 to 9.1 per 1,000 live births after 1995. These data reveal an emphasis on a growing public health issue regarding congenital heart disease. This discovery displays a need for heightened awareness in the scientific and medical industrial community to accelerate investigative research on emerging cardiovascular devices in an effort to confront congenital anomalies. One such device that has evolved over the past several decades is the pediatric membrane oxygenator. The pediatric membrane oxygenator, in conjunction with the heart lung machine, assists in the repair of most congenital cardiac defects. Numerous children born with congenital heart disease with or without congestive heart failure have experienced improved clinical outcomes in quality of life, survival, and mortality as a result of the inclusion of this technology during their cardiac surgical procedure. The purpose of this review is to report a summary of the published medical and scientific literature related to development of the pediatric membrane oxygenator from its conceptual evolutionary stages to artificially supporting whole body perfusion in the modern pediatric cardiac surgical setting.

Use of blood products in pediatric cardiac surgery

In pediatric cardiac surgery, there is a substantial gap between published recommendations or guidelines for blood product use and clinical practice. The drawbacks of blood transfusion are well acknowledged though. The aim of this paper is to present the rationale for packed red blood cells, fresh frozen plasma (FFP), and platelets used in pediatric patients. Blood hemoglobin level is the current trigger used for packed red blood cells transfusion, though commonly admitted to be suboptimal. An increase in hemoglobin level is likely to be associated with an increase in blood oxygen content and blood oxygen delivery. However, above a critical level of hemoglobin, normovolemic anemia is well tolerated, and any increase in hemoglobin will fail to increase oxygen consumption and therefore to improve end-organ oxygen supply. FFP is one way to address the coagulation factors deficiency induced by hemodilution, consumption, or hepatic insufficiency. The volume needed to increase these factors is not negligible. To avoid dilution and/or fluid overload, the use of clotting factor concentrate is recommended. The same remark can be made regarding the treatment of antithrombin III deficiency. Platelets infusion should be restricted to bleeding patients with thrombocytopenia and without surgical bleeding. In clinical studies, the prevention of bleeding through prophylactic infusion of platelets proved to be useless. Optimizing the use of blood products (avoiding overuse, underuse, and inappropriate use) is a challenging task in pediatric cardiac surgery. Data or guidelines cannot replace clinical judgment and the decision to transfuse is left to individual discretion, but the medical community needs to optimize its transfusion practice, otherwise policy-makers without similar expertise may step in to regulate the use of blood products.

Five-year experience with mini-volume priming in infants ≤5 kg: safety of significantly smaller transfusion volumes

Reducing the cardiopulmonary bypass (CPB) priming volume in congenital cardiac surgery is important because it is associated with fewer transfusions. This retrospective study was designed to compare safety and transfusion volumes between the mini-volume priming (MP) and conventional priming (CP) methods. Between 2007 and 2012, congenital heart surgery using CPB was performed on 480 infants (≤5 kg): the MP method was used in 331 infants (MP group, 69.0%), and the CP method was used in 149 infants (CP group, 31.0%). In the MP group, narrow-caliber (3/16″) tubing was used, and the pump heads were vertically aligned to shorten the tubing lengths. The smallest possible oxygenators and hemofilters were used, and vacuum drainage was applied. Ultrafiltration was vigorously applied during CPB to avoid excessive hemodilution. The mean age and body weight of the patients were 48 ± 41 (0-306) days and 3.8 ± 0.8 (1.3-5.0) kg, respectively. The total priming and transfusion volumes during CPB were lower in the MP group than in the CP group (141 ± 24 mL vs. 292 ± 50 mL, P < 0.001, and 82 ± 40 mL vs. 162 ± 82 mL, P < 0.001, respectively). In the MP group, the smallest priming volume was 110 mL. However, there was no significant difference in the lowest hematocrit level during CPB between the two groups (22 ± 3% vs. 22 ± 3%, P = 0.724). The incidence of postoperative neurological complications was not significantly different between the MP and CP groups (1.8% vs. 2.7%, P = 0.509). After adjustment for the Risk Adjustment for Congenital Heart Surgery category, body surface area, and age, MP was not an independent risk factor of postoperative neurological complications or early mortality (P = 0.213 and P = 0.467, respectively). The MP method reduced the priming volume to approximately 140 mL without increasing the risk of morbidity or mortality in infants ≤5 kg. The total transfusion volume during CPB was reduced by 50% without compromising hematocrit levels. We recommend the use of mini-volume priming, which is a safe and effective method for reducing transfusion volumes.

Effects of retrograde autologous priming on blood transfusion and clinical outcomes in adults: a meta-analysis

Objective:

Reducing the priming volume is an effective means of decreasing hemodilution and blood transfusion during cardiopulmonary bypass (CPB). The patient’s own blood was used to replace the crystalloid in the CPB circuit by retrograde autologous priming (RAP) in order to decrease the priming volume. Therefore, we performed a meta-analysis to investigate whether RAP could reduce blood transfusion and improve clinical outcomes.

Materials and Methods:

A comprehensive search was conducted for randomized, controlled trials (RCTs) exploring RAP in PubMed, Embase, The Cochrane Library, Google Scholar and Chinese literature databases (WanFang, WeiPu and CNKI). Clinical parameters and outcomes were focused on the lowest hematocrit (Hct) during CPB, the number of patients transfused blood intraoperatively, the number of patients transfused blood perioperatively, the number of blood units transfused, 24-hour chest tube drainage, hours to extubation, length of ICU stay, and length of hospital stay.

Results:

Ten trials, with a total of 1123 patients, were included. The number of patients transfused blood intraoperatively (RR = 0.39, 95% CI = [0.29, 0.53], p<0.00001, I2 = 40%) and perioperatively (RR = 0.53, 95% CI = [0.43, 0.66], p<0.00001, I2 = 0%) and the number of blood units transfused (SMD = -0.53, 95% CI = [-0.73, -0.33], p<0.00001, I2 = 14%) were all significantly reduced in the RAP group. No differences in the hours to extubation (SMD = -0.11, 95% CI = [-0.33, 0.12], p=0.37, I2 = 0%) and the length of ICU stay (SMD = -0.17, 95% CI = [-0.41, 0.08], p=0.18, I2 = 0%) were observed between the two groups.

Conclusion:

Compared to conventional priming, RAP could reduce transfusion in adults significantly, but had no effect on clinical outcomes, comparing to conventional priming. Further studies involving RAP are expected to investigate if this technique is beneficial to the patient.

Prolonged warm ischemia for transfusion-free arterial switch and ventricular septal defect surgery in a 4.5-Kg baby

Blood-free pediatric surgery is increasingly used for surgical correction of simple cardiopathies. Herein, we describe a complex cardiopathy, arterial switch operation and ventricular septal defect, with pre-operative thrombocytopenia in a 4.5 Kg baby treated with warm surgery and intermittent warm blood microplegia without any blood product. Bypass time was 89 min and aortic cross-clamp time 61 min. The maximal length of warm ischemia (time between microplegia injections) was 42 minutes. The postoperative course was uneventful. The patient was weaned off the ventilator after 7 hours, was discharged from the ICU on day 2 and was discharged from the hospital on day 7. The two main factors involved in this result were high pre-operative hemoglobin level and bypass technique with small prime volume, microplegia and warm perfusion. However, the success of this challenging case is also the result of teamwork and of rigorous patient care.

Blood transfusion in pediatric cardiac surgery

The aim of the study is to measure the volume of homologous blood needed for one pediatric patient during his hospital stay. Over a 4-month period, all the patients operated upon with a blood prime or requiring blood transfusion during their hospital stay were included in this study.The cardiopulmonary bypass protocol associates a miniaturized bypass circuit, vacuum-assisted venous drainage, and microplegia. The volume of each blood product opened is known and the volume of blood product remaining, following the last transfusion, is measured. Data collected areas follows: patient weight; hemoglobin level before surgery,during bypass, and in intensive care after the last transfusion;time to extubation; and degree of inotropic support.Forty-six patients weighing 5.1 1.5 kg were included in this study. Cardiopulmonary bypass priming volume was 100 mL for patients up to 3.5 kg, 120 mL for patients between 3.6 and 7.5 kg, and 160 mL for patients between 7.6 and 8.6 kg. The volume of blood transfusion was 271 112 mL, hemoglobin level before surgery was 10.3 1.7 g/dL, hemoglobin level during surgery was 11.0 1.5 g/dL, and hemoglobin level after the last transfusion was 12.3 2.4 g/dL. Time to extubation was 12 3.3 h, and inotropic support was enoximone in 37 patients,whereas 6 patients needed enoximone and epinephrine.No patient needed reexploration for bleeding and one patient received a platelet transfusion.The mean blood transfusion volume was equivalent to 60% of the patient’s total blood volume (estimated to be 80 mL/kg).

Mediastinitis in pediatric cardiac surgery: Prevention, diagnosis and treatment

In spite of advances in the management of mediastinitis following sternotomy, mediastinitis is still associated with significant morbidity. The prognosis is much better in pediatric surgery compared to adult surgery, but the prolonged hospital stays with intravenous therapy and frequent required dressing changes that occur with several therapeutic approaches are poorly tolerated. Prevention includes nasal decontamination, skin preparation, antibioprophylaxis and air filtration in the operating theater. The expertise of the surgical team is an additional factor that is difficult to assess precisely. Diagnosis is often very simple, being made on the basis of a septic state with wound modification, while retrosternal puncture and CT scan are rarely useful. Treatment of mediastinitis following sternotomy is always a combination of surgical debridement and antibiotic therapy. Continued use of numerous surgical techniques demonstrates that there is no consensus and the best treatment has yet to be determined. However, we suggest that a primary sternal closure is the best surgical option for pediatric patients. We propose a simple technique with high-vacuum Redon's catheter drainage that allows early mobilization and short term antibiotherapy, which thus decreases physiological and psychological trauma for patients and families. We have demonstrated the efficiency of this technique, which is also cost-effective by decreasing intensive care and hospital stay durations, in a large group of patients.

Specific requirements for bloodless cardiopulmonary bypass in neonates and infants; a review

A miniaturized cardiopulmonary bypass circuit enables the safe performance, in selected pediatric patients, of bloodless open heart surgery. As the latest survival rates in neonatal and infant cardiac surgery have become satisfactory, investigators have concentrated upon the improvement of existing procedures. Institutional guidelines and multidisciplinary efforts undertaken in the pre- and postoperative periods are of great importance, concerning bloodless CPB and should be seriously pursued by all involved caregivers.

This review reflects upon the selective, most relevant requirements for success of asanguinous neonatal and infant CPB: acceptable level of hemodilution during the CPB, patient preoperative hematocrit value and volume of CPB circuit. We present an assessment of practical measures that were also adapted in our institution to achieve an asanguinous CPB for neonatal and infant patients.

Perfusionist strategies for blood conservation in pediatric cardiac surgery

There is increasing concern about the safety of homologous blood transfusion during cardiac surgery, and a restrictive transfusion practice is associated with improved outcome. Transfusion-free pediatric cardiac surgery is unrealistic for the vast majority of procedures in neonates or small infants; however, considerable progress has been made by using techniques that decrease the need for homologous blood products or even allow bloodless surgery in older infants and children. These techniques involve a decrease in prime volume by downsizing the bypass circuit with the help of vacuum-assisted venous drainage, microplegia, autologous blood predonation with or without infusion of recombinant (erythropoietin), cell salvaging, ultrafiltration and retrograde autologous priming. The three major techniques which are simple, safe, efficient, and cost-effective are: a prime volume as small as possible, cardioplegia with negligible hydric balance and circuit residual blood salvaged without any alteration. Furthermore, these three techniques can be used for all the patients, including emergencies and small babies. In every pediatric surgical unit, a strategy to decrease or avoid blood bank transfusion must be implemented. A strategy to minimize transfusion requirement requires a combined effort involving the entire surgical team with pre-, peri-, and postoperative planning and management.

Small, smaller, smallest. Steps towards bloodless neonatal and infant cardiopulmonary bypass

In open heart surgery in neonates and small children, the cardiopulmonary bypass circuit surface and the priming volume are relatively large in relation to patient size and blood volume. Therefore, the use of allogeneic blood is inevitable to maintain the optimal hematocrit level during bypass. To avoid the deleterious effects of blood transfusion, as well as to reduce the contact surface of blood with artificial materials, we stepwise reduced the bypass circuit size. Use of the commercially available minimized elements and an adjusted set-up of the system allowed us to reduce usage of allogeneic blood in the prime and during the bypass. However, other supplemental measures are needed to obtain asanguineous cardiopulmonary bypass for neonatal and infant patients.