Cardiopulmonary Bypass Priming Volume Research Articles

Plasma-Free Strategy for Cardiac Surgery with Cardiopulmonary Bypass in Infants < 10 kg: A Retrospective, Propensity-Matched Study.

Infants < 10 kg undergoing cardiac surgery with cardiopulmonary bypass (CPB) may receive either fresh frozen plasma (FFP) or other solutions in the CPB priming volume. The existing comparative studies are controversial. No study addressed the possibility of total avoidance of FFP throughout the whole perioperative course in this patient population. This retrospective, non-inferiority, propensity-matched study investigates an FFP-free strategy compared to an FFP-based strategy. Among patients <10 kg with available viscoelastic measurements, 18 patients who received a total FFP-free strategy were compared to 27 patients (1:1.5 propensity matching) receiving an FFP-based strategy. The primary endpoint was chest drain blood loss in the first 24 postoperative hours. The level of non-inferiority was settled at a difference of 5 mL/kg. The 24-h chest drain blood loss difference between groups was -7.7 mL (95% confidence interval -20.8 to 5.3) in favor of the FFP-based group, and the non-inferiority hypothesis was rejected. The main difference in coagulation profile was a lower level of fibrinogen concentration and FIBTEM maximum clot firmness in the FFP-free group immediately after protamine, at the admission in the ICU and for 48 postoperative hours. No differences in transfusion of red blood cells or platelet concentrate were observed; patients in the FFP-free group did not receive FFP but required a larger dose of fibrinogen concentrate and prothrombin complex concentrate. An FFP-free strategy in infants < 10 kg operated with CPB is technically feasible but results in an early post-CPB coagulopathy that was not completely compensated with our bleeding management protocol.

Blood transfusion practices in cardiac anesthesia

Objective We have studied the variability of blood transfusion on hemodynamics and its complications during cardiac surgeries at a single center in Egypt. Patients and methods A total of 35 patients of both sexes, with ages from 21 to 70 years, scheduled for open heart surgeries were prospectively enrolled in this observational study between December 2019 and June 2020. Hemodynamic variables, such as mean arterial blood pressure and heart rate were recorded before induction (T1), after endotracheal intubation (T2), immediately before cardiopulmonary bypass (CPB) (T3), 30 min into CPB (T4), 15 min after successful weaning (T5), after sternal closure (T6), and upon arrival in the ICU (T7). The total amount of administered blood and blood products transfused intraoperatively and on the first day postoperatively; the total amount of fluids administered, including the CPB prime volume; and the total intraoperative urine output were recorded. Moreover, the number of patients who needed inotropic support, recovery time, time to extubation in the first 24 h postoperatively, length of ICU stay, and postoperative complication were recorded. Results We found that 68.6% (24 patients) of patients undergoing cardiac surgery received blood and/or blood product transfusion intraoperatively, and 31.4% (11 patients) were not transfused blood, but 14.3% (five patients) of them received blood postoperatively. Moreover, there were significant increases in the numbers of American Sociological Association III patients in blood transfusion group compared with other group, with increased need for inotropic drug and increased postoperative morbidity and mortality. Conclusion Blood transfusion in cardiac surgeries was associated with more incidences of postoperative complication and worse outcomes.

Plasma concentrations of cefazolin in pediatric patients undergoing cardiac surgery

Background:The guideline for antibiotic prophylaxis in pediatric cardiac surgery is currently unavailable, and the effects of cardiopulmonary bypass (CPB) may result in low plasma cefazolin concentrations and subsequent postoperative surgical site infections (SSIs).Aims:To demonstrate the calculated-unbound plasma concentrations of cefazolin during uncomplicated pediatric cardiac surgery.Settings and Design:A prospective observational study that included 18 patients <seven years of age, undergoing elective cardiac surgery with CPB.Materials and Methods:An intravenous infusion of cefazolin (25 mg.kg-1) was administered to patients over 30 minutes within 1 hour before skin incision (first dose). Another 25 mg.kg-1 infusion was administered to the CPB prime volume (second dose). Blood samples were obtained at eight time points: 15 minutes after the first dose (T1); before aortic cannulation (T2); immediately after CPB initiation (T3); 30 (T4), 60 (T5), and 120 (T6) minutes after CPB; 15 minutes after CPB discontinuation (T7), and at skin closure (T8). The total plasma cefazolin concentrations were measured using liquid chromatography tandem mass spectrometry.Results:The unbound cefazolin concentrations were calculated assuming 80%-protein binding. The median cefazolin levels were 18.1 (range 4.3-27.0), 11.9 (2.8-24.1), 31.4 (18.3-66.1), 23.4 (13.7-35.9), 20.2 (15.4-24.9), 17.7 (14.8-18.0), 15.6 (9.8-26.2), and 13.3 (8.3-24.6) μg.mL-1 from T1-T8, respectively. The cefazolin levels remained four times above the minimum inhibitory concentrations (MICs) for Methicillin-sensitive S. aureus (MSSA) and S. epidermidis in most patients, but they were inadequate for Enterobacter and E. coli.Conclusion:This regimen produced adequate plasma cefazolin concentrations for common organisms that cause SSIs after cardiac surgery.

Net Prime Volume Is Associated with Increased Odds of Blood Transfusion.

Hemodilutional anemia has been cited as a contributing factor to red blood cell (RBC) transfusions in cardiac surgery patients. Accordingly, efforts have been made to minimize hemodilution by reducing cardiopulmonary bypass (CPB) prime volume. We sought to assess the impact of these efforts on intraoperative RBC transfusions. We evaluated 21,360 patients undergoing coronary artery bypass with or without aortic valve surgery between July 2011 through December 2016 at any of 42 centers participating in the Perfusion Measures and Outcomes registry. The primary exposure was net CPB prime volume (total prime volume minus retrograde autologous prime volume) indexed to body surface area (mL/m2), which was further divided into quartiles (Q1: <262 mL/m2, Q2: 262-377 mL/m2, Q3: 377-516 mL/m2, and Q4: >516 mL/m2). The primary outcome was intraoperative RBC transfusion. We modeled the effect of index net prime volume on transfusion, adjusting for patient (age, gender, race, diabetes, vascular disease, previous myocardial infarction, ejection fraction, creatinine, preoperative hematocrit (HCT), total albumin, status, aspirin, and antiplatelet agents), procedural (procedure types) characteristics, surgical year, and hospital. The median net prime volume was 378 mL/m2 (25th percentile: 262 mL/m2, 75th percentile: 516 mL/m2). Relative to patients in Q1, patients in Q4 were more likely to be older, female, nondiabetic, have higher ejection fraction, have more ultrafiltration volume removed, and undergo more elective and aortic valve procedures (all p < .05). Patients in Q4 relative to Q1 were exposed to lower nadir HCTs on bypass, p < .05. The net prime volume was associated with an increased risk of transfusion (8.9% in Q1 vs. 22.6% in Q4, p < .001). After adjustment, patients in Q4 (relative to Q1) had a 2.9-fold increased odds (ORadj = 2.9, 95% CI [2.4, 3.4]) of intraoperative RBC transfusion. In this large, multicenter experience, patients exposed to larger net prime volumes were associated with greater adjusted odds of receiving intraoperative transfusions. Our findings reinforce the importance of efforts to reduce the net CPB prime volume. Based on these findings and other supporting evidence, the net prime volume should be adopted as a national quality measure.

Net Prime Volume Is Associated with Increased Odds of Blood Transfusion

Hemodilutional anemia has been cited as a contributing factor to red blood cell (RBC) transfusions in cardiac surgery patients. Accordingly, efforts have been made to minimize hemodilution by reducing cardiopulmonary bypass (CPB) prime volume. We sought to assess the impact of these efforts on intraoperative RBC transfusions. We evaluated 21,360 patients undergoing coronary artery bypass with or without aortic valve surgery between July 2011 through December 2016 at any of 42 centers participating in the Perfusion Measures and Outcomes registry. The primary exposure was net CPB prime volume (total prime volume minus retrograde autologous prime volume) indexed to body surface area (mL/m2), which was further divided into quartiles (Q1: &lt;262 mL/m2, Q2: 262–377 mL/m2, Q3: 377–516 mL/m2, and Q4: &gt;516 mL/m2). The primary outcome was intraoperative RBC transfusion. We modeled the effect of index net prime volume on transfusion, adjusting for patient (age, gender, race, diabetes, vascular disease, previous myocardial infarction, ejection fraction, creatinine, preoperative hematocrit (HCT), total albumin, status, aspirin, and antiplatelet agents), procedural (procedure types) characteristics, surgical year, and hospital. The median net prime volume was 378 mL/m2(25th percentile: 262 mL/m2, 75th percentile: 516 mL/m2). Relative to patients in Q1, patients in Q4 were more likely to be older, female, nondiabetic, have higher ejection fraction, have more ultrafiltration volume removed, and undergo more elective and aortic valve procedures (allp&lt; .05). Patients in Q4 relative to Q1 were exposed to lower nadir HCTs on bypass,p&lt; .05. The net prime volume was associated with an increased risk of transfusion (8.9% in Q1 vs. 22.6% in Q4,p&lt; .001). After adjustment, patients in Q4 (relative to Q1) had a 2.9-fold increased odds (ORadj= 2.9, 95% CI [2.4, 3.4]) of intraoperative RBC transfusion. In this large, multicenter experience, patients exposed to larger net prime volumes were associated with greater adjusted odds of receiving intraoperative transfusions. Our findings reinforce the importance of efforts to reduce the net CPB prime volume. Based on these findings and other supporting evidence, the net prime volume should be adopted as a national quality measure.

Early or late fresh frozen plasma administration in newborns and small infants undergoing cardiac surgery: the APPEAR randomized trial

BackgroundIn newborns and small infants undergoing cardiac surgery with cardiopulmonary bypass (CPB) and blood priming, it is unclear whether there is reduced blood loss if fresh frozen plasma (FFP) is added to the CPB priming volume. This single-centre, randomized trial tested the hypothesis that the administration of FFP after CPB (late FFP group) is superior to FFP priming (early FFP group) in terms of postoperative bleeding and overall red blood cell (RBC) transfusion. MethodsSeventy-three infants weighing <10 kg were randomly allocated to receive FFP to supplement RBCs in the CPB priming solution (n=36) or immediately after CPB (n=37). The primary endpoint was a difference in postoperative blood loss; secondary endpoints included the amount of RBCs and FFP transfused through the first 48 postoperative hours. ResultsAll patients were included in the analysis. Patients in the late FFP arm had greater postoperative mean blood loss than patients in the early FFP arm [33.1 (sd 20.6) vs 24.1 (12.9) ml kg−1; P=0.028], but no differences in transfusions were found. The subgroup of cyanotic heart disease patients had comparable results, but with greater use of RBCs in the late FFP group. ConclusionsIn infants undergoing cardiac surgery, FFP in the priming solution appears slightly superior to late administration in terms of postoperative bleeding. Clinical trial registration:www.ClinicalTrials.gov, NCT02738190.

Does retrograde autologous priming of the cardiopulmonary bypass circuit have an impact on haematocrit and blood transfusion in uncomplicated coronary artery bypass graft surgery? A retrospective analysis

Haemodilution occuring as a result of cardiopulmonary bypass prime volume increases the need for transfusion of allogenic blood products. Many techniques have been employed to reduce the same. Priming the CPB circuit with the patient's own blood is thought to decrease haemodilution and transfusion requirements.

Blood conservation strategies in cardiac surgery: more is better

Recent data show that up to 50% of heart procedures require blood transfusion, which can have adverse long- and short-term outcomes for the patient. This led to the updated 2011 Society of Thoracic Surgery (STS)/Society of Cardiovascular Anesthesiologists (SCA) guidelines in an attempt to adopt more effective blood conservation techniques. We present our results after the implementation of a more aggressive strategy for intraoperative blood conservation in cardiac surgery. Our cardiac surgery database was reviewed retrospectively, comparing outcomes from two different time periods, after the implementation of a more effective two-way blood conservation strategy beginning in March 2012: more aggressive intraoperative autologous donation (IAD) based on a newly constructed nomogram, and the use of a shorter length circuit of the cardiopulmonary bypass (CPB) which allowed for lower fluid volume as a prime. The method of retrograde autologous priming (RAP) was the same for both time periods. A total of 1126 patients (Group 1) were studied in a 12-month period (March 2012-February 2013) after the implementation of the new strategy, and compared with 3758 patients (Group 2) of the previous 36-month period (March 2009-February 2012). There was a significant reduction in the percent change of the intraoperative haematocrit between Groups 1 and 2 (14 vs 28%, P = 0.01), with an increase in the mean IAD volume (655 vs 390 ml, P = 0.02) and a reduction in the CPB priming volume (1000 vs 1600 ml, P = 0.03). Group 1 required significantly less blood transfusions in the perioperative period (29 vs 49%, P = 0.02) and had significantly reduced postoperative rates of respiratory failure (3 vs 7%, P = 0.03), pneumonia (1 vs 3.1%, P = 0.01), chest tube output (350 vs 730 ml, P = 0.01), reoperation for bleeding (1.2 vs 2.5%, P = 0.04) and length of stay (6.1 vs 8.2 days, P = 0.05). Blood conservation is safe and effective in reducing transfusions in cardiac surgery, minimizing perioperative morbidity and mortality. Aggressive IAD and low CPB prime, along with effective RAP, is the three-way blood conservation strategy that leads to improved outcomes in cardiac surgery.

019 * BLOOD CONSERVATION STRATEGIES IN CARDIAC SURGERY: MORE IS BETTER

Objectives: Recent data show that up to 50% of heart procedures require blood transfusion, which can have adverse long- and short-term outcomes for the patient. This led to the updated 2011 STS/SCA guidelines in an attempt to adopt more effective blood conservation techniques. We present our results after the implementation of a more aggressive strategy for intraoperative blood conservation in cardiac surgery. Methods: Our cardiac surgery database was reviewed retrospectively, comparing outcomes from two different time periods, after the implementation of a more effective two-fold blood conservation strategy beginning in March 2012: more aggressive intraoperative autologous donation (IAD) based on a newly constructed nomogram, and the use of a shorter length circuit of the cardiopulmonary bypass (CPB) which allowed for lower fluid volume as a prime. The method of retrograde autologous priming (RAP) was the same for both time periods. Results: A total of 1126 patients (group 1) were studied in a 12-month period (March 2012-February 2013) after the implementation of the new strategy, and compared to 2758 patients (group 2) from the previous 36-month period (March 2009-February 2012). There was a significant reduction in the percentage change of the intraoperative haematocrit between groups 1 and 2 (14% vs 28%, P = 0.01), with an increase in the mean IAD volume (655 ml vs 390 ml, P = 0.02) and a reduction in the CPB prime volume (1000 ml vs 1600 ml, P = 0.03). Group 1 required significantly fewer blood transfusions in the perioperative period (29% vs 49%, P = 0.02) and had significantly reduced postoperative rates of respiratory failure (3% vs 7%, P = 0.03), pneumonia (1% vs 3.1%, P = 0.01), chest tube output (350 ml vs 730 ml, P = 0.01), reoperation for bleeding (1.2% vs 2.5%, P = 0.04), and length of stay (6.1 days vs 8.2 days, P = 0.05). Conclusions: Aggressive IAD and low CPB prime, along with effective RAP, is the three-fold blood conservation strategy that leads to improved outcomes in cardiac surgery.

Vacuum-Assisted Venous Drainage, Angel or Demon: PRO?

Vacuum-assisted venous drainage (VAVD) was proposed to optimize venous drainage during bypass through femoral venous cannulation. It is currently used in both adult and pediatric surgery when siphon gravity venous drainage is suboptimal. In pediatric surgery, the major advantages of VAVD are a significant decrease in cardiopulmonary bypass prime volume and an improved drainage with all collateral benefits. To limit gravity drainage, we use a two-level heart–lung machine dedicated to pediatric perfusion. The top level of the cardiotomy reservoir is positioned at the patient atrial level, making it possible to downsize the length and diameter of venous and arterial lines. Since 2008, a negative pressure of approximately −30 mmHg has been used for all patients. Initiation of bypass is performed in a classical way with a cardiotomy reservoir open; vacuum is added as soon as the maximal gravity drainage is reached. During bypass, when the blood level in the reservoir decreases to the safety limit level, a small increase in negative pressure is used to improve venous drainage. For weaning from bypass, the negative pressure is gradually decreased to zero, then the reservoir is opened and the venous line progressively closed. Prime volumes were significantly reduced to 100 mL for small neonates, 125 mL for infants, and 175 mL for older children with flow up to 1.5 L/min−1. A low prime volume is expected to improve blood conservation and decrease donor exposure, prevent drawbacks of transfusion (immunomodulation, infection), increase the incidence of blood-free surgery in smaller babies, and decrease whole body systemic inflammation by decreasing surface of foreign material in contact with blood and inflammation associated with blood transfusion. The main drawbacks described have been retrograde flow in the venous line with cerebral air embolus and an increased incidence of gaseous microemboli. These drawbacks are avoidable through appropriate training of perfusionists. When negative pressure is “reasonable,” complications are more theoretical than significant in clinical practice. A technique with a benefit/drawback ratio of 1:0 is utopian, but the advantages of VAVD far outweigh any potential drawbacks when applied properly.

The effect of cardiopulmonary bypass prime volume on the need for blood transfusion after pediatric cardiac surgery

There is increasing awareness that erythrocyte transfusions after pediatric cardiac surgery have deleterious effects. Despite reports of decreased transfusion requirements associated with smaller cardiopulmonary bypass circuits, the relationship between circuit prime volume and need for transfusion has not been systematically examined. Pediatric patients at our institution who underwent cardiopulmonary bypass between January 2005 and December 2010 were reviewed. Demographics, intraoperative data, and transfusion of packed red blood cells were retrospectively recorded. Cardiopulmonary bypass prime volume was indexed by patient body surface area. Logistic regression analysis was used to correlate these variables with need for transfusion. In the perioperative period, 1912 patients received transfusions and 266 did not. In univariate analysis, indexed prime volume was a significant predictor of transfusion (odds ratio, 1.007; P < .001). Other significant variables in univariate analysis included age, surgeon, Risk Adjustment for Congenital Heart Surgery 1 (RACHS-1) category, preoperative hemoglobin, total bypass time, aortic crossclamp time, use and duration of deep hypothermic circulatory arrest, lowest body core temperature, and cardiopulmonary bypass flow rate. Previous cardiac surgery was not a significant predictor. In multivariable analysis controlling for RACHS-1 category, surgeon, minimal core body temperature, and preoperative hemoglobin, indexed prime volume remained an independent predictor of transfusion (odds ratio, 1.006; 95% confidence interval, 1.005-1.007, P < .001). Perioperative need for transfusion in pediatric cardiac surgical patients is independently related to the prime volume of the cardiopulmonary bypass circuit. It therefore seems prudent to minimize circuit prime volumes to avoid unnecessary use of blood products.

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).

Hemostatic consequences of a non‐fresh or reconstituted whole blood small volume cardiopulmonary bypass prime in neonates and infants

Despite aggressive measures to miniaturize the cardiopulmonary bypass (CPB) circuit in neonates and infants, the CPB prime volume is often at least as large as the patients' blood volume. We conducted an observational study to characterize the hemostatic consequences of a CPB prime consisting of either non-fresh or reconstituted whole blood. Hematocrit, fibrinogen, platelet count, plasminogen, anti-thrombin III (AT-III), and factors (F) II, V, VII, IX, and X of 30 neonates and infants undergoing cardiac surgery with CPB utilizing either a non-fresh or reconstituted whole blood prime were prospectively evaluated at eight time points. Following protamine administration, microvascular bleeding was treated by protocol. The hemostatic composition of the CPB prime was the same following the use of either non-fresh or reconstituted whole blood. The CPB prime platelet count (mean +/- SD) was 5.87 +/- 2.84 x 10(3) microl(-1) when compared to a preoperative platelet count of 298 +/- 142 x 10(3) microl(-1) (P < 0.0001). Twenty patients received 17.3 +/- 9.2 ml x kg(-1) (0.86 +/- 0.46 units x kg(-1)) of platelets with significant improvement in platelet count. Nine patients received 16.7 +/- 13.4 ml x kg(-1) (0.84 +/- 0.67 units x kg(-1)) of cryoprecipitate with significant improvements in FVIII and fibrinogen. Non-fresh or reconstituted whole blood as a component of a small volume CPB prime in neonates and infants induces clinically significant dilutional thrombocytopenia in conjunction with less significant reductions in fibrinogen, FII, FV, FVII, FVIII, FIX, FX, plasminogen, and AT-III.

Influence of Intraoperative Fluid Volume on Cardiopulmonary Bypass Hematocrit and Blood Transfusions in Coronary Artery Bypass Surgery

A hematocrit (Hct) of less than 25% during cardiopulmonary bypass (CPB) and transfusion of homologous packed red blood cells (PRBC) are each associated with an increased probability of adverse events in cardiac surgery. Although the CPB circuit is a major contributor to hemodilution intravenous (IV) fluid volume may also significantly influence the level of hemodilution. The objective of this study was to explore the influence of asanguinous IV fluid volume on CPB Hct and intraoperative PRBC transfusion. After Institutional Review Board approval, a retrospective chart review of 90 adult patients that had undergone an elective, isolated CABG with CPB was conducted. Regression analysis was used to determine if pre-CPB fluid volume was associated with the lowest CPB Hct and the incidence of an intraoperative PRBC transfusion. In separate multivariate analyses, higher pre-CPB fluid volume was associated with lower minimum CPB Hct (p&lt; .0001), and higher minimum CPB Hct was associated with a decreased probability of PRBC transfusion (p&lt; .0001). Compared to patients that received &lt;1600 mL (n= 55) of pre-CPB fluid, those that received &gt;1600 mL (n= 35) had a decreased mean low CPB Hct (22.4% vs 25.6%,p&lt; .0001), an increased incidence of a CPB Hct &lt;25% (74% vs. 38%,p= .0008) and PRBC transfusion (60% vs. 16%,p&lt; .0001), and increased median PRBC units transfused (2.0 vs 1.0,p= .1446) despite no significant difference in gender, age, patient size, baseline Hct, or CPB prime volume. Patients that received a PRBC transfusion (n= 30) received a significantly higher volume of pre-CPB fluid than nontransfused patients (1800 vs. 1350 mL,p= .0039). These findings suggest that pre-CPB fluid volume can significantly contribute to hemodilutional anemia in cardiac surgery. Optimizing pre-CPB volume may preserve baseline Hct and help limit intraoperative hemodilution.

Usefulness of Low Prime Perfusion Pediatric Circuit in Decreasing Blood Transfusion

We tested the efficiency of small prime volume in decreasing the blood requirement during pediatric cardiac surgery. This is a retrospective analysis of transfusion in 259 consecutive patients weighing <15 kg. We downsized the bypass circuit and avoided noncritical components to obtain a cardiopulmonary bypass prime volume, including a cardioplegia circuit of 140 ml for patients up to 6 kg, and of 170 ml for those weighing 6-15 kg. For intra- and postoperative care, transfusions were limited to 1 unit of packed red blood cells and 1 unit of fresh frozen plasma in 129 of the 134 patients weighing <6 kg. Seventy-six of 125 (61%) patients who were between 6 kg and 15 kg had bloodless surgery. None of the 259 patients had platelets infusion. In transfused cases, only eight patients (3%) needed more than two different donor products. In bloodless cases, hemoglobin values were 11.5 +/- 1.8 g/dl before, 9.4 +/- 1.7 g/dl during, and 10.5 +/- 1.8 g/dl after surgery. No adverse effects of this procedure were encountered. Small prime volume is efficient and safe in decreasing blood use in pediatric surgery.

180 ml and less: Cardiopulmonary bypass techniques to minimize hemodilution for neonates and small infants

To determine the efficacy of decreasing cardiopulmonary bypass (CPB) prime volume for neonates and small infants by using low prime oxygenators, small diameter polyvinyl chloride (PVC) tubing and removing the arterial line filter (ALF) in an effort to reduce intraoperative exposure to multiple units of packed red blood cells (PRBC). Two retrospective database studies comparing neonatal CPB prime volume were undertaken: Study 1--A CPB circuit consisting of a 1/8 inch arterial line, a 3/16 inch venous line and a low prime oxygenator with 172 ml total circuit prime (n=74) was compared to a circuit with a 3/16 inch arterial line, a 1/4 inch venous line and a higher prime oxygenator with a 350 ml total circuit prime (n=74). Study 2--The 172 ml circuit (n=389) was compared to a circuit that included an ALF and had a total circuit prime volume of 218 ml (n=389). Study 1--of the 74 neonates and small infants whose CPB prime volume was 350 ml, 19 were exposed to two or more intraoperative exogenous PRBC units while only 3 neonates and small infants in the 172 ml prime group (n=74) received two or more units (p = 0.0002). Study 2--of the 389 neonates and small infants where an ALF was used (prime volume 218 ml), 54 were exposed to two or more exogenous PRBC units while only 36 of the 389 patients where an ALF was not used (prime volume 172 ml) received two or more units of intraoperative PRBCs (p = 0.0436). Decreasing the neonatal and small infant extracorporeal circuit prime volume by as little as 46 ml resulted in significantly fewer multiple exposures to exogenous PRBC units.

Reduction of hemodilution in small adults undergoing open heart surgery: a prospective, randomized trial

Given that there is an association between the degree of hemodilution during cardiopulmonary bypass (CPB) and postoperative complications, patients-outcome might be improved if the nadir hematocrit concentration is kept within an optimal range. Smaller patients are more likely to have a low hematocrit during CPB: this phenomenon may be related, at least partially, to the extreme hemodilution induced by a large fixed CPB priming volume. Forty patients with a body surface area (BSA) < 1.7 m2 undergoing open heart operations were randomized to either standard CPB with full prime volume (control group) or reduced prime extracorporeal circuit and vacuum-assisted venous drainage (VAVD) (study group). There were no significant differences between the groups with respect to baseline characteristics, body surface area, hematologic profile and operative data. Clinical outcomes were similar. Nadir hematocrit and hemoglobin on bypass were significantly lower in the control group (22 +/- 2.3 vs. 24 +/- 2.5%, p < 0.02 and 7.4 +/- 0.7 vs. 8 +/- 0.9 g/dl, p < 0.04, respectively). Postoperative chest tube drainage was significantly higher in the control group (272 +/- 253 vs. 139 +/- 84 ml, p < 0.04). There was no difference in blood transfusion in the two groups (0.5 +/- 1.14 vs. 1.0 +/- 1.77 units of packed red blood cells (PRBC), p = 0.29). Lowering CPB priming volume by means of using a small oxygenator and vacuum-assisted venous drainage (VAVD) resulted in a significant decrease of intraoperative hemodilution. This technique should be strongly considered for patients with a small BSA (<1.7 m2) undergoing open heart surgery.

Perfusion technique for nonhaemic cardiopulmonary bypass prime in neonates and infants under 6 kg body weight.

Cardiopulmonary bypass (CPB) in neonates and infants is associated with significant haemodilution when priming of the CPB circuit is accomplished without transfusion of homologous blood components. The degree of haemodilution and, thus, the requirements for blood transfusion may be reduced when the CPB circuit is miniaturized without compromising patient safety. Between January 2002 and October 2003, selected neonates and small infants were operated on using a nonhaemic prime extracorporeal circuit. CPB priming volume could be reduced from 300 mL to 190 mL by using a dedicated neonatal CPB console with mast-mounted roller pump heads. Reduction of priming volume resulted from shortening of all CPB lines to the minimum, downsizing of all CPB lines, exclusion of unused CPB components, use of vacuum-assisted venous drainage and from close co-operation between the perfusionist, cardiac surgeon and anaesthesiologist. The reduction in priming volume was achieved without eliminating the arterial line filter as safety device. A total of nine patients weighing between 3.2 and 5.9 kg (mean 4.7 kg) and with a body surface area of 0.22-0.35 m2 (mean 0.29 m2) were operated on with the use of the modified neonatal CPB circuit and a nonhaemic prime. Bypass time varied from 38 to 167 min (mean 96 min). The mean haematocrit on CPB was 22.5% with a range of 17-29%. The postoperative course of all patients was uneventful. A significant reduction in CPB priming volume makes nonhaemic prime CPB in neonates and small infants undergoing complex repair of congenital heart defects possible.

Dosing Aprotinin: Is Weight-Adjustment the Way to Go?

To the Editor: We have read with interest the study of Nuttall and colleagues in which they tried to optimize the dosing of aprotinin by weight-adjustment (1). Weight-adjustment, however, neglects the prime-volume of the cardiopulmonary bypass (CPB) system as well as the pump prime dose. Given a normal adult (65 kg body weight) the only difference between the 250 KIU/mL group in Nuttall’s study and the “Full-Dose” group is the pump prime load (88 mg vs. 280 mg). Furthermore, an 88-mg pump prime load results in a far lower concentration than the 4.4 mg/kg bolus given intravenously. Besides the pump prime load, the volume of the CPB system is of special interest, especially in pediatric cardiac surgery where the volume of the CPB system is several fold higher than the circulating blood volume. The smaller the patient the greater is this discrepancy, leading to aprotinin plasma levels that are ineffective in terms of blood loss reduction in pediatric patients (2). Given these considerations, it may be more appropriate to base the aprotinin dose on the estimated circulating blood volume during bypass (CBVbypass = patient’s estimated blood volume + CPB prime-volume), rather than simply basing it on the patient’s body weight. By multiplying CBVbypass with the desired concentration of aprotinin in plasma and the hematocrit (see formula below), the needed amount of aprotinin can easily be calculated, no matter whether it is an adult patient or a pediatric patient:MATH This initial loading dose is then to be followed by a maintanance infusion as described by Nuttall and colleagues (1). While in the study of Nuttall et al. the measured plasma concentrations were up to some 70% higher than the desired aprotinin plasma levels (1), dosing aprotinin according to the above-mentioned formula would prevent this happening. C. Schmidt A. Reich H. Van Aken D. Stanojevic M. Booke

Retrograde autologous priming of the cardiopulmonary bypass circuit - effective and safe blood conservation

Many patients require a blood transfusion after cardiac surgery. Dilution of the patient's blood with the pump prime may contribute to this need. Retrograde autologous priming (RAP) of the cardiopulmonary bypass (CPB) circuit reduces CPB prime volume, and hence haemodilution [1]. The purpose of the present study was to compare RAP of the CPB circuit with normal priming in reducing both the percentage of patients requiring homologous blood and the volume of blood transfused. The incidence of complications was noted.