Perfusionist strategies for blood conservation in pediatric cardiac surgery

Encouraging results of blood conservation in neonatal open-heart surgery

OBJECTIVE

To report early outcomes of blood conservation in neonatal open-heart surgery.

METHODS

Ninety-nine patients undergoing neonatal open-heart surgery during the implementation of a blood conservation program between May 2021 and February 2023 were reviewed. Patients either received traditional blood management (blood prime, n = 43) or received blood conservation strategies (clear prime, n = 56). Baseline characteristics and outcomes were compared between groups.

RESULTS

There was no difference in body weight (median, 3.2 kg vs 3.3 kg; P = .83), age at surgery (median, 5 days vs 5 days; P = .37), distribution of The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Categories categories or duration of cardiopulmonary bypass. Patients in the clear prime group had higher preoperative hematocrit (median, 41% vs 38%; P < .01), shorter postoperative mechanical ventilation time (median, 48 hours vs 92 hours; P = .02) and postoperative intensive care unit length of stay (median, 6 days vs 9 days; P < .01) than patients in the blood prime group. Fourteen patients (25%) in the clear prime group, including 1 Norwood patient, were discharged without any transfusion. Among patients within the clear prime group, hospitalizations without blood exposure were associated with higher preoperative hematocrit (median, 43% vs 40%; P = .02), shorter postoperative mechanical ventilation times (median, 22 hours vs 66 hours; P = .01) and shorter postoperative hospital stays (median, 10 days vs 15 days; P = .02).

CONCLUSIONS

Bloodless surgery is possible in a significant proportion of neonates undergoing open-heart surgery, including the Norwood operation, even in the early stages of experience. Early clinical results are favorable but long-term follow-up and continued efforts are warranted to prove safety and reproducibility.

Safety of bloodless open-heart surgery on cardiopulmonary bypass in selected children: A single center experience with minimal invasive extracorporeal circulation

INTRODUCTION

Bloodless cardiac surgery refers to open-heart surgery without blood or blood products. The cardiopulmonary bypass (CPB) circuits are primed with crystalloid solely, and there is no intraoperative blood transfusion.

METHODS

Our program considers bloodless congenital cardiac surgery with a minimal invasive extracorporeal circulation (MiECC) system for patients above 10 kg of weight. We performed a single-center retrospective cohort study of all consecutive patients undergoing bloodless cardiac surgery for congenital heart defects between January 2016 and December 2018.

RESULTS

A total of 164 patients were reviewed (86 male and 78 female) at a median age of 9.6 years (interquartile range (IQR), 4.5-15), a weight of 32 kg (IQR, 16-55), preoperative hemoglobin 13.7 g/dl (IQR, 12.6-14.9), and preoperative hematocrit of 40.4% (IQR, 37.2-44.3). Median CPB time was 81.5 min (IQR, 58-125), and median hematocrit coming off CPB was 26% (IQR, 23-29.7). The congenital heart surgery risk (STAT) category was distributed in STAT 1 for 70, STAT 2 for 80, STAT 3 for 9, and STAT 4 for 5 patients. Most patients (95%) were extubated in the operating room with a low complication rate during the hospital stay (14.6%). Only 6 (4%) patients needed a blood transfusion during the postoperative period, with a higher incidence of complications during the hospital course (p < 0.001).

CONCLUSIONS

Bloodless congenital heart surgery with MiECC system is safe in low-surgical-risk patients. Our patients had a low rate of complications and short hospital stays.

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.

Insight Into Kidney Protection by Vacuum-Assisted Venous Drainage in Adult Cardiac Operation ― A Multicenter Study ―

BACKGROUND

The relationship between venous congestion and acute kidney injury (AKI) in cardiac surgery after cardiopulmonary bypass has not thoroughly investigated. Vacuum-assisted venous drainage (VAVD) reduces venous congestion, so we hypothesized that it would reduce the incidence of AKI in cardiovascular surgery.Methods and Results: We used a retrospective propensity score-matched analysis to evaluate the effect of VAVD on AKI in adult patients undergoing cardiac surgery. The primary outcomes were AKI and renal replacement therapy (RRT). Multivariable logistic regression was used to explore the association between VAVD exposure and adverse kidney outcomes. Of 15,387 eligible subjects, 13,480 and 1,907 had gravity drainage (GD) or VAVD, respectively, during cardiopulmonary bypass. On the basis of propensity scores, there were 1,468 matched patient pairs for GD and VAVD. The average central venous pressure (CVP) in the GD group was higher than in the VAVD group (4.43±1.23 mmHg vs. 2.30±0.98 mmHg, P<0.001). The occurrence of AKI and RRT was statistically significantly different in the 2 groups [(600/1,468, 40.87%) vs. (445/1,468, 30.31%), P<0.001; (36/1,468, 2.45% vs. 8/1,468; 0.54%), P<0.001, respectively)]. Multivariate logistic regression analysis revealed that VAVD was effective in protecting kidney function.

CONCLUSIONS

VAVD was associated with a lower CVP and lower incidence of AKI, suggesting it protects adult cardiac patients from adverse renal outcomes.

A Surgeon's Perspective on Blood Conservation Practice in Pediatric Cardiac Surgery

Blood conservation practice in pediatric cardiac surgery has not been consistently adopted as quality improvement in many centers despite known risks associated with allogeneic blood products, shortage of donors, and costs. There are many blood conservation strategies available which collectively minimize exposure to allogeneic transfusion by maximizing the use of autologous red cells. These strategies are safe, reproducible, and have been implemented in clinical practice collectively with great efficacy for all patient ages and complexity levels. Institutional commitment to a set guideline will improve their blood conservation practice and quality outcome. The purpose of this article is to provide early career and practicing congenital cardiac surgeons with practical information concerning blood conservation strategies which can be considered for implementation in any pediatric cardiac surgery program, and which may be of particular value in resource-limited programs.

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.

Comparison of three autotransfusion devices for utilization in the pediatric population

Introduction:

A device that may help attenuate the amount of homologous blood product given to pediatric cardiac surgical patients is the autotransfusion device. Three separate autotransfusion devices were selected for evaluation. The Sorin Xtra, Fresenius Continuous Autotransfusion System Plus (CATS*plus), and the Fresenius Continuous Autotransfusion System Smart (CATSmart) were evaluated based on the mechanical processes of each device, hematocrit value of the salvaged packed red cell product, time of processing, and the advantageous accessories with each device.

Methods:

Each of the autotransfusion devices were used to collect salvageable blood from the surgical field as well as to process residual blood from the cardiopulmonary bypass circuit after decannulation. The cell salvage process was performed in accordance with the manufacturer’s instructions for use and the recommended settings for processing and washing. The Sorin Xtra device had the 55 mL bowl set up for all cases, while the Fresenius continuous autotransfusion systems utilized the standard disposable for each device.

Results:

Each cell salvage device was employed during 30 pediatric cardiac surgery procedures, and data for each device, was broken down into four groups based on patient weight (0-10, 10-20, 20-40, and >40 kg). For all patient sizes, the Sorin Xtra tended to produce the greatest volume of cell saver product (55-825 mL) as compared to the CATS*plus and CATSmart devices (7-550 mL and 0-860 mL, respectively). The Continuous Autotransfusion System Smart tended to produce the highest hematocrit product, ranging from 44 to 81%.

Discussion:

Through this evaluation, it was determined the continuous autotransfusion systems provided the highest hematocrit with the lowest recovered packed red cell volume, while the Sorin Xtra packed red cell product showed to have a lower hematocrit with a larger packed red cell volume. Each device proved effective within our pediatric population.

Retrograde Autologous Priming Technique to Reduce Hemodilution during Cardiopulmonary Bypass in the Pediatric Cardiac Patient

Blood conservation techniques during pediatric congenital heart surgery continue to be a vital strategy in reducing hemodilution during cardiopulmonary bypass. Development of mini circuits, retrograde autologous priming, modified ultrafiltration, and use of a cell saver are methods adopted by pediatric heart programs to limit transfusions. Excessive hemodilution may warrant the need for transfusion in the pediatric patient, which carries significant risks in the overall care of the patient. Retrograde autologous priming is a safe and effective way to limit the amount of hemodilution, and thereby reduce the need for transfusion.

Bloodless priming of the cardiopulmonary bypass circuit: determinants of successful transfusion-free operation in neonates and infants with a maximum body weight of 7 kg

We currently perform open-heart procedures using bloodless priming of cardiopulmonary bypass circuits regardless of a patient's body weight. This study presents results of this blood-saving approach in neonates and infants with a body weight of up to 7 kg. It tests with multivariate analysis factors that affect perioperative transfusion. A total of 498 open-heart procedures were carried out in the period 2014-2016 and were analysed. Priming volume ranged from 73 ml for patients weighing up to 2.5 kg to 110 ml for those weighing over 5 kg. Transfusion threshold during cardiopulmonary bypass was 8 g/dl of haemoglobin concentration. Transfusion factors were first analysed individually. Variables with a p-value lower than 0.2 underwent logistic regression. Extracorporeal circulation was conducted without transfusion of blood in 335 procedures - that is, 67% of cases. Transfusion-free operation was achieved in 136 patients (27%) and was more frequently observed after arterial switch operation and ventricular septal defect repair (12/18=66.7%). It was never observed after Norwood procedure (0/33=0%). Lower mortality score (p=0.001), anaesthesia provided by a certain physician (p=0.006), first chest entry (p=0.013), and higher haemoglobin concentration before going on bypass (p=0.013) supported transfusion-free operation. Early postoperative mortality was 4.4% (22/498). It was lower than expected (6.4%: 32/498). In conclusion, by adjusting the circuit, cardiopulmonary bypass could be conducted without donor blood in majority of patients, regardless of body weight. Transfusion-free open-heart surgery in neonates and infants requires team cooperation. It was more often achieved in procedures with lower mortality score.

Routine Application of Bloodless Priming in Neonatal Cardiopulmonary Bypass: A 3-Year Experience

A restrictive transfusion strategy led us to routinely try to conduct donor-blood free open-heart surgery even in neonates. The cardio-pulmonary bypass (CPB) circuit was minimized by priming volumina at 73 ml for the smallest patients with body weight up to 2.5 kg and 85-95 ml for those with body weight of more than 2.5 kg, and by positioning the console as close as possible to operation table. Measures were applied to save blood during the procedure. Transfusion threshold of 8 g/dl hemoglobin was retained. Effort was made to avoid transfusion while on CPB or to postpone transfusion towards CPB end. From 2013 to 2015, 149 consecutive neonates underwent 150 open-heart procedures without blood in priming volume. Weight was lower than 2.5 kg in five instances. The most frequent operations were arterial switch operation (n = 54) and Norwood procedure (n = 17). Transfusion-free operation was achieved in 44 procedures. The great majority (42/44 = 95%) involved biventricular repair and included 50% (27/54) of arterial switch operations. 106 patients were transfused: 63 mostly towards CPB end, and 43 after coming off bypass. Transfusion-free procedures were associated with postoperative lower lactate concentration (p = 0.0013) and shorter duration of mechanical ventilation (p = 0.0009). Seven patients were discharged from hospital without getting any transfusion of blood or blood products. In conclusion, routine application of bloodless priming in neonatal cardiopulmonary bypass is safe and beneficial. It results into a good number (29%= 44/150) of transfusion-free operations. Postponing transfusion towards CPB end favors an overall restrictive transfusion strategy for all patients.

Vacuum assist: angel or demon CON

Vacuum-assisted venous drainage (VAVD) to enhance venous return during cardiopulmonary bypass (CPB) was described as early as 1958 but was not widely used until the late 1990s. VAVD was initially used to facilitate the use of smaller cannulas with ministernotomy but was increasingly used to allow reduction in CPB circuit size while maintaining CPB flow rates. This innovation was made without planned consideration to CPB circuit design, most critically that of the venous reservoir. Clinical reports of prime reduction facilitated by VAVD in both adult and pediatric CPB were associated with reduced nadir hematocrit and rates of transfusion that encouraged the proliferation of VAVD in CPB. Concomitantly, investigators have reported both in vitro and in vivo significantly increased arterial emboli associated with the use of VAVD, mostly related to accelerated venous air entrainment. In vitro studies continue to confirm this association and likely underestimate the resulting embolic load as a result of flawed study design. While the evidence for VAVD is equivocal, our understanding of the clinical impact of gaseous microemboli in CPB is similarly limited, most likely confined to blood-brain barrier disruption. It is only after two decades that CPB component design is receiving serious attention in terms of air handling. The ethics of innovation in the field of CPB warrant careful consideration. The application of VAVD is not without consequence.

Pre-filling of the extracorporeal circuit with autologous blood is safe, but not effective in optimizing biocompatibility in high-risk patients

OBJECTIVES

Haemodilution resulting from crystalloid priming of the cardiopulmonary bypass circuit represents a major risk factor for blood transfusions in high-risk cardiac surgery patients. We designed this study to evaluate the effects of antegrade autologous priming (AAP) on reducing perioperative blood transfusion and markers of the inflammatory response in older patients (>75 years).

METHODS

Seventy-two patients undergoing first-time coronary bypass and/or aortic valve replacement were prospectively randomised to a cardiopulmonary bypass (CPB) with or without AAP. AAP was performed by adding the patient's own blood to the prime solution (mean 280 ml). Perfusion and anaesthetic techniques were as usual. The haematocrit was maintained at a minimum of 21% during CPB. Patients were well matched for all preoperative variables, including established transfusion risk factors. The primary endpoint was the requirement of red cell transfusion. The surrogate endpoints were renal function, inflammatory response and ischaemic parameters. Blood samples were drawn pre- and intraoperatively and at intervals of 6 hours till POD 6.

RESULTS

Current analysis shows no differences in patients receiving homologous packed red cell transfusions. Also, markers of the inflammatory response (IL6, IL8), renal function (cystatin C, creatinine) and myocardial ischaemia (troponin T, CK-MB) were comparable in both groups (p>0.05). Clinical outcomes were similar with respect to pulmonary, renal and hepatic function, length of ICU stay and hospital stay.

CONCLUSION

These data suggest that antegrade autologous priming is a safe procedure, but an ineffective way for improving biocompatibility and reducing the need for blood transfusion in older patients.

The successful introduction of an adapted form of the mini extra corporeal circulation used for cardiac surgery in an obese patient

Obese patients undergoing cardiac surgery have been shown to have a high risk of developing postoperative complications, specifically: increased length of hospital stay, readmission to intensive care unit, acute renal failure, deep sternal wound infections and new onset of atrial fibrillation.A custom-made circuit was created to allow the use of Mini Extra Corporeal Circulation (MECC) but permitting the switch to a closed siphon drainage system in the case of difficulties.To limit artificial surface contact a small oxygenating device (Admiral, Eurosets) was employed in spite of the patients size. This adapted circuit permits a feasible and safer approach to using MECC. This report suggests that smaller oxygenators could be integrated into clinical practice in an adult MECC configuration, even for more obese patients, limiting artificial surface contact.

Use of a miniaturized cardiopulmonary bypass circuit in neonates and infants is associated with fewer blood product transfusions

Miniaturized bypass circuits, including the Kids D100 oxygenator and the D130 arterial filter, were specially designed to reduce blood transfusions in small infants undergoing cardiac surgery. This study compared the number of blood product transfusions and short-term outcome between patients younger than 1 year undergoing cardiac surgery with a conventional and a miniaturized bypass circuit, after controlling for baseline characteristics and surgical complexity by 1:1 matching. Adjusted odds ratios (ORs) and 95% confidence intervals for exposure to transfusions and to any additional transfusion were estimated from binary and polytomous regression models. Of the 804 patients enrolled retrospectively, 246 were analyzed after matching. The use of the miniaturized circuit required a lower priming volume, 265.5 vs. 432.4 mL, p < 0.001, fewer packed red blood cell (PRBC) transfusions, 1.4 vs. 2.0 U, p < 0.001, and fewer platelet transfusions on the day of surgery, 57.7% vs. 76.4%, p < 0.001. After adjustment for the use of antifibrinolytics, the ultrafiltration rate, and the year of surgery, the use of the miniaturized circuit was independently related to a reduced risk of additional PRBC transfusions, OR 0.04 (0.01, 0.13), and exposure to platelet transfusions, OR 0.78 (0.63, 0.96). Short-term outcome was similar.