Dilutional and modified ultrafiltration reduces pulmonary hypertension after operations for congenital heart disease: a prospective randomized study

Strategies to attenuate maladaptive inflammatory response associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) initiates an intense inflammatory response due to various factors: conversion from pulsatile to laminar flow, cold cardioplegia, surgical trauma, endotoxemia, ischemia-reperfusion injury, oxidative stress, hypothermia, and contact activation of cells by the extracorporeal circuit. Redundant and overlapping inflammatory cascades amplify the initial response to produce a systemic inflammatory response, heightened by coincident activation of coagulation and fibrinolytic pathways. When unchecked, this inflammatory response can become maladaptive and lead to serious postoperative complications. Concerted research efforts have been made to identify technical refinements and pharmacologic interventions that appropriately attenuate the inflammatory response and ultimately translate to improved clinical outcomes. Surface modification of the extracorporeal circuit to increase biocompatibility, miniaturized circuits with sheer resistance, filtration techniques, and minimally invasive approaches have improved clinical outcomes in specific populations. Pharmacologic adjuncts, including aprotinin, steroids, monoclonal antibodies, and free radical scavengers, show real promise. A multimodal approach incorporating technical, circuit-specific, and pharmacologic strategies will likely yield maximal clinical benefit.

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.

Effects of modified ultrafiltration and conventional ultrafiltration combination on perioperative clinical outcomes in pediatric cardiac surgery: A meta-analysis

BACKGROUND

This meta-analysis was performed to review the effects of the addition of modified ultrafiltration (MUF) and conventional ultrafiltration (CUF) to CUF alone on postoperative hemoglobin, surgical and ultrafiltration data, and postoperative clinical outcomes in pediatric patients undergoing cardiac surgery.

METHODS

A systematic search was performed to identify randomized controlled clinical trials that compared MUF and CUF combination with CUF alone in pediatric cardiac surgery undergoing cardiopulmonary bypass (CPB) in PubMed, Embase, Cochrane Library, and Web of Science without any language or date limitation in February 2020. For each included trial, the primary outcomes including post-CPB and postoperative hematocrit, surgical and ultrafiltration data, postoperative clinical outcomes including volume of chest tube drainage within 48 hours after surgery and perioperative blood requirement, ventilation support duration, and length of stay day in the intensive care unit (ICU) and hospital were collected and analyzed. The analysis was conducted using STATA version 12.0.

RESULTS

A total of 8 trials encompassing 405 patients were included in this analysis. Analysis indicated that MUF + CUF increased the post-CPB hematocrit (Standard mean difference, SMD = 1.85, 95% confidence interval, 95% CI 0.91-2.79). Meanwhile, ultrafiltration volume was higher in CUF+MUF infants than CUF-alone infants (SMD = 1.46, 95% CI 0.51-2.41, P = .003). The clinical outcomes, including postoperative hemodynamic changes, prime volume, blood requirement, chest tube drainage volume, mechanical ventilation duration, and ICU duration, were unclear because of the unstable sensitivity analyses.

CONCLUSIONS

Beneficial effects of using MUF and CUF for pediatric cardiac surgery, including increase post-CPB hematocrit and ultrafiltration volume when compared with CUF alone. Meanwhile, MUF and CUF did not significantly influence the postoperative hospital stay duration, CPB, and aortic occlusion duration.

Transthoracic intracardiac catheters in perioperative management of pediatric cardiac surgery patients: a single-center experience

BACKGROUND

Transthoracic intracardiac catheters inserted under direct vision in the pulmonary artery and left atrium during cardiac surgery play major roles in the management of patients with complex congenital heart disease. We aimed to analyze the utility of transthoracic intracardiac catheters in the perioperative management of pediatric cardiac surgery patients and review catheter-related morbidity.

METHODS

The computerized register of all pediatric cardiac surgery patients in whom transthoracic intracardiac catheters were inserted from 2012 to 2019 in a tertiary referral center were reviewed.

RESULTS

Transthoracic pulmonary artery and left atrial catheters were inserted in 89 and 71 patients, respectively. The most common indications for pulmonary artery and left atrial catheters were total anomalous pulmonary venous connection (52%) and total cavopulmonary connection (58%) respectively. The most common reason for elevated pulmonary artery and left atrial pressure after cardiopulmonary bypass was left ventricular dysfunction. Transthoracic pulmonary artery catheters helped in diagnosing pulmonary hypertensive crisis (29%), surgical decision-making (14%), and ventilator therapy (16%). Left atrial catheters helped in the diagnosis of left ventricular dysfunction (54%). The incidence of morbidity was 8.9% for transthoracic pulmonary artery catheters and 9.8% for left atrial catheters.

CONCLUSION

Transthoracic pulmonary artery catheters help in the diagnosis and management of pulmonary hypertensive crisis, for making perioperative surgical decisions, and during ventilator therapy. Transthoracic left atrial catheters help in the diagnosis of left ventricular dysfunction in the perioperative period. The diagnostic and treatment benefits provided by transthoracic intracardiac catheters outweigh the minor adverse events, supporting their continued use in the perioperative period.

Practical conduct of open heart procedures for congenital heart lesions

Open heart surgery on infants with congenital heart lesions can be challenging not only in terms of the surgical procedure itself but also for setting up ideal conditions for safe and smooth conduct of cardiopulmonary bypass (CPB). The surgeon has to deal with a variety of lesions in a subgroup of patients who offer little room for any error. Familiarity with the principles of CPB, check lists and protocols go a long way in improving outcome in this critical group of patients.

Ultrafiltration in Pediatric Cardiac Surgery Review

Introduction:

The use of cardiopulmonary bypass in pediatric cardiac surgery is associated with significant inflammation, fluid overload, and end-organ dysfunction yielding morbidity and mortality. For decades, various intraoperative ultrafiltration techniques such as conventional ultrafiltration, modified ultrafiltration (MUF), zero-balance ultrafiltration (ZBUF), and combination techniques (ZBUF-MUF) have been used to mitigate these toxicities and promote improved postoperative outcomes. However, there is currently no consensus on the ultrafiltration technique or strategy that yields the most benefit for infants and children undergoing open heart surgery.

Methods:

A librarian-conducted PubMed literature search from 1990 to 2018 yielded 90 clinical studies or publications on the various forms of ultrafiltration and the impact on physiologic markers and clinical outcomes. All publications were reviewed, summarized, and conclusions synthesized. The data sets were not combined for systematic or meta-analysis due to significant heterogeneity in study protocols and patient populations.

Results:

Modified ultrafiltration significantly promotes improved myocardial function, reduction in fluid overload, and reduced bleeding and transfusion complications. Furthermore, ZBUF has shown a consistent reduction in inflammatory cytokines and improved pulmonary function and compliance. There is conflicting evidence that MUF, ZBUF, and ZBUF-MUF culminate in reduced ventilation time and intensive care unit stay.

Conclusion:

Various modes of ultrafiltration have been shown to be associated with improved physiologic function or clinical outcomes in pediatric cardiac surgery. There are some inconsistent trial results that can be explained by heterogeneity in ultrafiltration, clinical staff preferences, and institution protocols. Ultrafiltration has some essential benefit as it is ubiquitously used at pediatric heart centers; however, the optimal protocol could be yet identified.

Reevaluating the Importance of Modified Ultrafiltration in Contemporary Pediatric Cardiac Surgery

Objective(s): Modified ultrafiltration has gained wide acceptance as a powerful tool against cardiopulmonary bypass morbidity in pediatric cardiac surgery. The aim of our study was to assess the importance of modified ultrafiltration within conditions of contemporary cardiopulmonary bypass characteristics. Methods: Ninety–eight patients (overall cohort) weighing less than 12 kg undergoing surgical repair with cardiopulmonary bypass were prospectively enrolled in a randomized protocol to receive modified and conventional ultrafiltration (MUF group) or just conventional ultrafiltration (non-MUF group). A special attention was paid to forty-nine neonates and infants weighing less than 5 kg (lower weight (LW) cohort). Results: Post-filtration hematocrit was significantly higher in the MUF group for both cohorts (overall cohort p = 0.001; LW cohort p = 0.04), but not at other time points. During the postoperative course, patients in the MUF group received fewer packed red blood cells, (overall cohort p = 0.01; LW cohort p = 0.07), but required more fresh frozen plasma (overall cohort p = 0.04; LW cohort p = 0.05). There was no difference between groups in hemodynamic state, chest tube output, duration of mechanical ventilation, respiratory parameters, duration of intensive care unit, and hospitalization stay. Conclusions: If conventional ultrafiltration provides adequate hemoconcentration modified ultrafiltration does not provide additional positive benefits except for reduction in blood cell transfusion, This, however, comes at the cost of needing more fresh frozen plasma. Of particular importance is that this also applies to infants with weight bellow 5 kg where modified ultrafiltration was supposed to have the greatest positive impact.

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.

Perioperative and Anesthetic Considerations in Total Anomalous Pulmonary Venous Connection

Total anomalous pulmonary venous connection (TAPVC) is a potentially devastating form of congenital heart disease in which all pulmonary blood flow returns to the systemic venous circulation rather than the left atrium. Anomalous pulmonary venous flow may be obstructed at birth, and affected infants present with severe cyanosis and poor cardiac output unresponsive to standard resuscitation with prostaglandin. Obstructed TAPVC remains one of the few indications for emergent neonatal cardiac surgery. This review will discuss the physiology and perioperative management of isolated TAPVC without associated cardiac lesions.

Impact of Modified Ultrafiltration on Morbidity after Pediatric Cardiac Surgery

Cardiopulmonary bypass is a double-edged sword. Without it, corrective cardiac surgery would not be possible in the majority of children with congenital heart disease. However, much of the perioperative morbidity that occurs after cardiac surgery can be attributed to a large extent to pathophysiologic processes engendered by extracorporeal circulation. One of the challenges that has confronted pediatric cardiac surgeons has been to minimize the consequences of cardiopulmonary bypass. Ultrafiltration is a strategy that has been used for many years in an effort to attenuate the effects of hemodilution that occur when small children undergo surgery with cardiopulmonary bypass. Over the past several years, a modified technique of ultrafiltration, commonly known as modified ultrafiltration, has been used with increasing enthusiasm. Multiple studies have been undertaken to assess the effects of modified ultrafiltration on organ function and postoperative morbidity following repair of congenital heart defects. This review attempts to evaluate current available scientific evidence on the impact of modified ultrafiltration on organ function and morbidity after pediatric cardiac surgery.

Developing dual hemofiltration plus cardiopulmonary bypass in rodents

BACKGROUND

Emerging therapies for prolonged cardiac arrest (CA) include advanced circulatory interventions like emergency cardiopulmonary bypass (ECPB) and continuous venovenous hemofiltration (CVVHF). However, preclinical studies are limited because of the absence of a practical method of using CVVHF along with ECPB in rodents.

METHODS

We modified a CA model with ECPB resuscitation to include the CVVHF circuit. Adult rats were cannulated via the femoral artery or vein and the jugular vein for the ECPB circuit. A new circuit for CVVHF was added to allow ECPB and CVVHF to be started simultaneously. CVVHF blood flow at 3 mL/min could be controlled with a screw clamp during ECPB. After cessation of ECPB, the CVVHF flow was maintained using a roller pump. The filtration rate was controlled at 40 mL/h/kg in the standard volume of CVVHF and 120 mL/h/kg in the high volume (HV) of CVVHF. The driving force of hemofiltration was evaluated by monitoring transmembrane pressure and filter clearance (FCL).

RESULTS

Transmembrane pressure in both groups was stable for 6 h throughout CVVHF. FCL of blood urea nitrogen and potassium in the standard volume group was significantly less than the HV group (P < 0.01). FCL of blood urea nitrogen and potassium was stable throughout the CVVHF operation in both groups.

CONCLUSIONS

We developed a method of CVVHF along with ECPB in rodents after CA. We further demonstrated the ability to regulate both standard and HV filtration rates.

Clinical outcome and blood transfusion after infant cardiac surgery with a routine use of conventional ultrafiltration

OBJECTIVE

Priming-related hemodilution is the culprit behind excessive body water accumulation, postoperative coagulopathy and enhanced blood transfusion in infant cardiac surgery patients. In this retrospective, observational study, clinical data were analyzed to assess the effect of conventional ultrafiltration on allogenic blood transfusion and patient clinical outcome.

METHODS

All infants with a bodyweight up to 10 kg who underwent consequent cardiac surgery in 2011 and 2012 were eligible for the audit. Seventy patients, operated in accordance with existing pediatric protocol, enrolled in the control group. The study group consisted of 55 patients who were operated employing conventional ultrafiltration during bypass and recently adjusted hematocrit targets. The following variables were primarily investigated: hematocrit and colloid osmotic pressure value, total volume of blood products transfused and duration of postoperative mechanical ventilation. Secondary outcome measures were: postoperative urine production, postoperative blood loss, length of stay at the intensive care unit and hospital stay.

RESULTS

There were no significant differences between the groups in relation to demographics or hematological and cardiopulmonary bypass data. The ultrafiltration volume removed from circulation during bypass in the study group was 171 ± 99 ml. No significant difference between the groups was found with regard to the total allogenic blood transfusion (study group 216 ± 92 ml versus control group 191 ±93 ml; p = 0.136). All recorded clinical end points, duration of mechanical ventilation, duration of chest tube in situ, stay in ICU and stay in hospital, were similar between the groups.

CONCLUSIONS

Routine use of conventional ultrafiltration during the cardiac surgery for patients with a bodyweight less than 10 kg was a safe technique that allowed us to achieve higher hematocrit levels at the end of the operation without additional transfusions of allogenic blood. On the other hand, ultrafiltration did not improve the clinical end points.

Modified ultrafiltration during cardiopulmonary bypass and postoperative course of pediatric cardiac surgery

Context:

The use of cardiopulmonary bypass (CPB) provokes the inflammatory responses associated with ischemic/reperfusion injury, hemodilution and other agents. Exposure of blood cells to the bypass circuit surface starts a systemic inflammatory reaction that may causes post-CPB organ dysfunction, particularly in lungs, heart and brain.

Evidence Acquisition:

We investigated in the MEDLINE, PUBMED, and EMBASE databases and Google scholar for every available article in peer reviewed journals between 1987 and 2013, for related subjects to CPB with conventional or modified ultrafiltration (MUF) in pediatrics cardiac surgery patients.

Results:

MUF following separation from extracorporeal circulation (ECC) provides well known advantages in children with improvements in the hemodynamic, pulmonary, coagulation and other organs functions. Decrease in blood transfusion, reduction of total body water, and blood loss after surgery, are additional benefits of MUF.

Conclusions:

Consequently, MUF has been associated with attenuation of morbidity after pediatric cardiac surgery. In this review, we tried to evaluate the current evidence about MUF on the organ performance and its effect on post-CPB morbidity in pediatric patients.

Current ultrafiltration techniques before, during and after pediatric cardiopulmonary bypass procedures

Ultrafiltration, which is currently considered as a standard method to remove excess water administered during pediatric cardiopulmonary bypass (CPB), aims to minimize the adverse effects of hemodilution, such as tissue edema and blood transfusion. Three ultrafiltration techniques can be used before, during and after CPB procedures, including conventional ultrafiltration (CUF), modified ultrafiltration (MUF) and zero-balance ultrafiltration (Z-BUF). These methods are widely different, but they have common benefits on hemoconcentration, less requirement for blood products, and reduction of the systemic inflammatory responses (SIRS). The present review attempts to restate these ultrafiltration circuitries, application methods, end-points, and clinical impacts.

The benefits of continuous ultrafiltration in pediatric cardiac surgery

BACKGROUND

Systemic inflammatory response and capillary leak syndrome, caused by extracorporeal circulation, have negative effects on the function of vital organs during the postoperative period. Modified ultrafiltration (MUF) has been developed as an alternative method to reduce the detrimental effects of cardiopulmonary bypass. The aim of this prospective, randomized study is to analyze the effects of MUF in a pediatric population undergoing congenital cardiac surgery.

METHODS

Twenty-seven patients who underwent open-heart surgery at our institution were included in this prospective study. They were randomized into two groups as follows: Group I (n=14) of conventional ultrafiltration during bypass and Group II (n=13) receiving both conventional and modified ultrafiltration during and after the cessation of the bypass, respectively. The amount of prime volume, postoperative chest drain loss, transfusion requirements, hemodynamical parameters, duration of mechanical ventilatory support, and length of intensive care unit stay were compared between the two groups. During the postoperative period, the concentrations of hematological, biochemical and inflammatory parameters were also compared by analyzing the blood samples obtained at various time points.

RESULTS

MUF resulted in a significant increase in hemoglobin, hematocrit and platelet levels, and significantly reduced the amount of chest tube output and transfused blood and blood products. MUF also shortened the duration of postoperative mechanical ventilatory support, length of the intensive care unit stay and improved postoperative hemodynamical parameters. During the early postoperative hours, IL-8 is significantly reduced in patients undergoing MUF, however, the concentrations of IL-8 were similar in both groups at the end of 24 h.

CONCLUSIONS

MUF decreases the duration of mechanical ventilatory support, the length of intensive care unit stay, the need for blood transfusion and improves postoperative hemodynamics. It is associated with increased levels of hemoglobin, hematocrit and platelets. We can conclude that MUF attenuates the inflammatory response by decreasing the levels of inflammatory mediators.

Perfusion approaches to blood conservation

There are several perfusion techniques that can contribute to blood conservation. Minimizing existing circuit components, using mini-circuits and the maneuver of retrograde autologous priming can be considered steps in prime reduction. Microplegia systems may also reduce systemic as well as cardiac hemodilutional effects. Cell savers can scavenge shed blood, wash the red cells, and may return the red cells to the patient in a concentrated form. When a patient is already hemodiluted, ultrafiltation can be used to hemoconcentrate the patient and to drive their existing hemoglobin levels up. Ultimately, the optimal form of blood conservation comes from team-work, communication, and a combination of efforts.

Continuous hemodiafiltration during cardiopulmonary bypass in infants

The homologous blood prime in cardiopulmonary bypass circuits contributes a significant electrolyte and metabolite load in small infants. The efficacy of hemofiltration and continuous hemodiafiltration of the blood prime in preventing metabolic disturbances in small infants was compared in two groups of 60 patients each. Blood pH, base excess, and calcium concentrations decreased during cardiopulmonary bypass in the hemofiltration group. The acid-base balance was well preserved during cardiopulmonary bypass by continuous hemodiafiltration. This therapeutic strategy may confer an advantage in maintaining more physiological conditions during cardiopulmonary bypass in small infants.

Modified and conventional ultrafiltration during pediatric cardiac surgery: Clinical outcomes compared

OBJECTIVE

This prospective study compared clinical outcomes after heart surgery between three groups of infants with congenital heart disease. One group received dilutional conventional ultrafiltration (group D), another received modified ultrafiltration (group M), and a third group received both dilutional conventional and modified ultrafiltration (group B). We hypothesized that group B patients would have the best clinical outcome.

METHODS

Children younger than 1 year undergoing heart surgery for biventricular repair by the same surgeon were randomly allocated to one of the three study groups. Patient management was standardized, and intensive care staff were blinded to group allocation. Primary outcome measure was duration of postoperative mechanical ventilation. Other outcome measures recorded included total blood products transfused, duration of chest tube in situ, chest tube output, and stays in intensive care and in the hospital.

RESULTS

Sixty infants completed study protocol. Mean age and weight were as follows: group D (n = 19), 61 days, 4.3 kg; group M (n = 20), 64 days, 4.5 kg; and group B (n = 21), 86 days, 4.4 kg. Preoperative and intraoperative characteristics were similar between groups. Ultrafiltrate volumes obtained were 196 +/- 93 mL/kg in group D, 105 +/- 33 mL/kg in group M, and 261 +/- 113 mL/kg in group B. There were no significant differences between groups for any outcome variable. Technical difficulties prevented completion of modified ultrafiltration in 2 of 41 infants.

CONCLUSION

There was no clinical advantage in combining conventional and modified ultrafiltration. Because clinical outcomes were similar across groups, relative risks of the ultrafiltration strategies may influence choice.

Modulation of systemic inflammatory response after cardiac surgery

Cardiac surgery and cardiopulmonary bypass initiate a systemic inflammatory response largely determined by blood contact with foreign surfaces and the activation of complement. It is generally accepted that cardiopulmonary bypass initiates a whole-body inflammatory reaction. The magnitude of this inflammatory reaction varies, but the persistence of any degree of inflammation may be considered potentially harmful to the cardiac patient. The development of strategies to control the inflammatory response following cardiac surgery is currently the focus of considerable research efforts. Diverse techniques including maintenance of hemodynamic stability, minimization of exposure to cardiopulmonary bypass circuitry, and pharmacologic and immunomodulatory agents have been examined in clinical studies. This article briefly reviews the current concepts of the systemic inflammatory response following cardiac surgery, and the various therapeutic strategies being used to modulate this response.

Technique and results for integration of the quest MPS all-blood cardioplegia delivery unit for modified ultrafiltration

All blood cardioplegia delivery units offer the advantage of removing additional crystalloid volumes associated with multidose crystalloid or 4:1 blood cardioplegia. Further reductions in crystalloid and prime volumes can be achieved if the cardioplegia delivery unit can be integrated as the modified ultrafiltration (MUF) unit as well. This article reports our technique and results for integration of the Quest MPS all-blood cardioplegia delivery unit (Quest Medical, Allen, TX) for modified ultrafiltration. The charts of 50 consecutive patients were reviewed. Patient age ranged from 3 days to 5 years. There were nine neonates. Patient weight ranged from 1.7 to 20.4 kg. Standard prime volumes were 400 cc for patients weighing less than 12 kg, and 800 cc for patients weighing more than 12 kg. Cardiopulmonary bypass time ranged from 32 to 231 minutes. All patients were perfused with corporeal temperatures above 31 degrees C except Norwood cases. MUF time ranged from 5 to 15 minutes with an average of 10.2 minutes. Volume removed ranged from 100 to 600 cc with an average of 239 cc. There was one mortality (2%), which was unrelated to MUF. Additional prime volume was not required to initiate MUF through the MPS cardioplegia unit. The Quest MPS all-blood CPG unit can be safely and effectively integrated as a MUF unit without additional prime volumes. This approach allows for mild hypothermic cardiopulmonary bypass, multidose all-blood CPG, and MUF to be used with tremendous limitation of crystalloid usage.

Elimination of proinflammatory cytokines in pediatric cardiac surgery: analysis of ultrafiltration method and filter type

OBJECTIVE

This study was undertaken to assess whether different filter types or ultrafiltration methods influence inflammatory markers in pediatric cardiac surgery.

METHODS

Forty-one children younger than 5 years were prospectively randomized to groups A (polyamid filter with conventional ultrafiltration), B (polyamid filter with modified ultrafiltration), C (polysulfon filter with conventional ultrafiltration), and D (polysulfon filter with modified ultrafiltration). Interleukin 6, interleukin 10, tumor necrosis factor, terminal complement complex, and lactoferrin were measured before the operation (T0), before rewarming (T1), after ultrafiltration (T2), at 6 (T3) and 18 hours (T4) after the operation, and in the ultrafiltrate.

RESULTS

All markers changed with both ultrafiltration methods, both filter types, and in all groups (except tumor necrosis factor) along the T0 to T4 observation time (P <.0001). Their patterns of changes were different for terminal complement complex, with less decrease after use of the polysulfon filter (P <.05), and among groups A through D for interleukin 6 (P =.01), with more decrease in group C than group A (P <.02). Interleukin 10 decreased with the polyamid filter (P <.001) but not with the polysulfon filter. In the ultrafiltrate, tumor necrosis factor was higher with the polysulfon filter than the polyamid filter (6.8 +/- 5 pg/mL vs 4.0 +/- 3.7 pg/mL, P <.05). The ultrafiltrate/plasma ratio of interleukin 6 was higher with conventional ultrafiltration than modified ultrafiltration (0.018 +/- 0.017 vs 0.004 +/- 0.007, P <.005).

CONCLUSIONS

The polysulfon filter showed a filtration profile for inflammatory mediators superior to that of the polyamid filter for interleukin 6, tumor necrosis factor, and interleukin 10. Interleukin 6 was most efficiently removed by conventional ultrafiltration with a polysulfon filter, and tumor necrosis factor was best removed by modified ultrafiltration with a polysulfon filter, whereas other inflammatory mediators were not influenced by filter type or ultrafiltration method. Therefore combined conventional and modified ultrafiltration with a polysulfon filter may currently be the most effective strategy for removing inflammatory mediators in pediatric heart surgery.

Efficacy of a criterion-driven transfusion protocol in patients having pediatric cardiac surgery

OBJECTIVES

Low-hematocrit bypass is one technique used to prevent allogeneic transfusion during cardiopulmonary bypass. The purpose of this study is to determine the efficacy of a criterion-driven transfusion protocol and the effect of low-hematocrit bypass with moderate hypothermia in pediatric cardiac surgery.

METHODS

Seventy-five children who underwent cardiopulmonary bypass with low-hematocrit bypass for repair of congenital heart disease were studied. Criteria for red blood cell transfusion included anemia with a hematocrit level of less than 15% during bypass and 20% after bypass. During cardiopulmonary bypass, venous oxygen saturation, hematocrit values, and regional cerebral oxygenation were continuously monitored. Arterial lactate levels were measured postoperatively.

RESULTS

All patients had an uncomplicated perioperative course, and no perioperative death occurred. Twenty-two patients (29.3%) received a transfusion, and 53 (70.7%) patients did not. The hematocrit levels before and after modified ultrafiltration in the transfused group (21.6 +/- 5.5%, 26.6 +/- 6.5%) were significantly higher than those in the nontransfused group (18.9 +/- 3.7%, 23.1 +/- 4.1%) (P <.05). There was no significant difference between the group's arterial lactate levels immediately after admission to the intensive care unit and 1 day after the operation. The arterial lactate levels 6 hours after the admission to the intensive care unit for the nontransfused patients were higher than with the transfused patients (4.3 +/- 3.0 versus 2.5 +/- 1.5 mmol/L, (P <.05). For arterial lactate level, the relation with patients' weight had the highest correlation (R = 0.678, P <.0001).

CONCLUSIONS

A criterion-driven transfusion program can be effective, and low-hematocrit bypass with a hematocrit value below 20% may affect lactate production or clearance from the body.

Antioxidant therapy with Salvia miltiorrhiza decreases plasma endothelin-1 and thromboxane B2 after cardiopulmonary bypass in patients with congenital heart disease

OBJECTIVE

The endothelium-derived vasoconstrictor endothelin-1 is increased after cardiopulmonary bypass in children with congenital heart defects. This study determines whether antioxidant therapy with Salvia miltiorrhiza injection, an herb extract containing phenolic compounds, prevents the postoperative increase of endothelin-1. The relationship between endothelin-1 and the endothelium-derived prostacyclin (prostaglandin I2) and thromboxane A2 postoperatively is also investigated.

METHODS

Twenty children with congenital heart defects and pulmonary hypertension were randomly assigned to group A (placebo control, n=10) or B (200 mg/kg Salvia miltiorrhiza intravenously after anesthesia induction and at the time of rewarming, respectively; n =10) before cardiac surgery. Central venous blood samples were taken before operation (T(0)), 10 (T(1)) and 30 minutes (T(2)) after starting cardiopulmonary bypass, 10 (T(3)) and 30 minutes (T(4)) after aortic declamping, and 30 minutes (T(5)) and 24 hours (T(6)) after termination of cardiopulmonary bypass. Plasma lipid peroxidation product malondialdehyde, myocardial specific creatine kinase-MB activity, thromboxane B2, and 6-keto-prostaglandin F(1 alpha) (stable metabolites of thromboxane A2 and prostaglandin I2) were measured.

RESULTS

Malondialdehyde increased significantly at T(1) in group A and remained significantly higher than in group B thereafter (P <.05). Malondialdehyde in group B did not significantly increase over time. At T(5), plasma creatine kinase-MB, thromboxane B2, and endothelin-1 in group B were lower than in group A (P <.05); malondialdehyde correlated significantly with creatine kinase-MB (r = 0.71, P =.0005). At T(6), endothelin-1 negatively correlated with the 6-keto-prostaglandin F(1 alpha)/thromboxane B2 ratio (r = -0.64, P =.0025).

CONCLUSION

Antioxidant therapy reduces myocardial damage and attenuates postoperative vasoactive mediator imbalance.

The endothelin system in pulmonary hypertension

Pulmonary hypertension (PH) may result from numerous clinical entities affecting the pulmonary circulation primarily or secondarily. It is recognized that vascular endothelial dysfunction contributes to the development and perpetuation of PH by creating an imbalance between vasodilating and antiproliferative forces and between vasoconstrictive and proliferative forces. In that context, endothelin-1 (ET-1) overproduction was rapidly targeted as a plausible contributor to the pathogenesis of PH. The lung is recognized as the major site for ET production and clearance. In all animal models of PH studied, circulating plasma ET-1 levels are elevated, accompanied by an increase in lung tissue expression of the peptide. The use of selective ETA and dual ETA-ETB receptor antagonists in these models both in prevention and in therapeutic studies have confirmed the contribution of ET-1 to the rise in pulmonary vascular tone, pulmonary medial hypertrophy, and right ventricular hypertrophy. This is found consistently in models affecting the pulmonary circulation primarily or producing PH secondarily. Recent clinical trials in patients with pulmonary arterial hypertension have confirmed the therapeutic effectiveness of ET-receptor antagonists in humans. We offer a systematic review of the pathogenic role of the ET system in the development of PH as well as the rationale behind the preclinical and ongoing clinical trials with this new class of agents.

Current strategies for optimizing the use of cardiopulmonary bypass in neonates and infants

The use of cardiopulmonary bypass is still necessary for the repair of many congenital cardiac defects. However, exposure to cardiopulmonary bypass can still lead to major morbidity and sometimes mortality, especially in neonates and infants, despite a perfect surgical repair. Various research-based strategies have been used to minimize some of the complications related to cardiopulmonary bypass, including the systemic inflammatory response, hemodilution, and transfusion requirement. This overview provides some of the strategies that we use in our practice in applying cardiopulmonary bypass in the repair of congenital cardiac defects in neonates and infants.

Best Practice for Cardiopulmonary Bypass in the High-Risk Elderly Patient

The management of cardiopulmonary bypass has evolved over the last 50 years resulting in a largely consistent approach to both adult and pediatric perfusion. Very little has been written or prospectively researched on the best practice for cardiopulmonary bypass in the high-risk elderly patient, despite the challenge this patient cohort presents compared to the general adult population and the rapidly increasing number of such patients undergoing cardiac surgery. We propose a framework for perfusion strategies for the high-risk elderly patient from our current understanding of cardiopulmonary bypass. It should stimulate discussion for a consensus on perfusion strategies for the elderly and encourage further research into perfusion variables as they relate to the outcome of patients of advanced age.

Inflammation After Cardiopulmonary Bypass: Therapy for the Postpump Syndrome

Cardiopulmonary bypass (CPB) is used in most, but not all, complex heart operations. CPB is associated with a systemic inflammatory response in adults and children. Many materials-dependent (exposure of blood to non- physiologic surfaces and conditions) and materials-in dependent (surgical trauma, ischemia-perfusion to the organs, changes in body temperature, and release of endotoxin) factors during CPB have been implicated in the etiology of this complex response. The mechanisms involved may include complement activation, release of cytokines, leukocyte activation with expression of ad hesion molecules, and production of various vasoactive and immunoactive substances. Postpump inflamma tion may lead to postoperative complications and may result in respiratory failure, renal dysfunction, bleeding disorders, neurologic dysfunction, altered liver func tion, and ultimately multiple organ failure. Significant efforts are being made to decrease the generation and effects of postpump inflammation. Interventions to this end have included avoiding CPB when possible, im proving the biocompatibility of the involved mechani cal devices, and administering medications that main tain cellular integrity. This article provides an overview of the etiology, pathophysiology, and treatment of postpump inflammation. Perhaps with additional in sight into this syndrome, CPB can be made a safer and more efficacious modality of cardiorespiratory support. Copyright© 2001 by W.B. Saunders Company.

Cardiopulmonary bypass in infants and children

Cardiopulmonary bypass (CPB) systems have evolved from futuristic visions of surgical pioneers to a safe and efficient tool in the therapy of treatment of cardiac disorders. There are many significant differences in the physiology between neonates and adult patients. There are currently very few congenital cardiac malformations that cannot be addressed effectively with surgical therapy. Yet, the necessity of CPB in the repair of these patients can still result in significant morbidity. A clearer understanding of the effects of CPB, hypothermia, and circulatory arrest is evolving and there is a considerable amount of research in these areas. It seems likely that modification of current CPB systems, minimization of exposure, and surgical techniques to avoid or limit the adverse effects may reduce mortality and morbidity in the future. The problems faced in these complex patients and procedures require that infant and neonatal cardiac surgery be performed in specialized centers with a multidisciplinary approach and specialized personnel. Future improvements in technology will likely result in improved long term outcome for children with congenital cardiac disease. Copyright 2000 by W.B. Saunders Company

Pulmonary vascular resistance after cardiopulmonary bypass in infants: effect on postoperative recovery

OBJECTIVE

We sought to define the contemporary clinical effect of increased pulmonary vascular resistance in infants after congenital heart operations with cardiopulmonary bypass.

METHODS

Fifteen infants (median age, 0.31 years; median weight, 5.1 kg) underwent cardiac operations involving cardiopulmonary bypass (range, 49-147 minutes). Pulmonary vascular resistance was measured in the immediate postoperative period in the intensive care unit by means of the direct Fick principle, with respiratory mass spectrometry to measure oxygen consumption. The effect of ventilation with an inspired oxygen fraction of 0.65, with additional infusion of L -arginine, substance P, and inhaled nitric oxide, was assessed and subsequently correlated with the length of mechanical ventilation from the end of cardiopulmonary bypass to successful extubation.

RESULTS

Overall, pulmonary vascular resistance at baseline (11.7 +/- 5.6 WU. m(2)) could be reduced to a minimum of 6.1 +/- 3.5 WU. m(2). The ventilatory time was 0.86 to 14.9 days (median, 1.75 days) and correlated directly with the lowest pulmonary vascular resistance value achieved during the pulmonary vascular resistance study (r (2) = 0.64, P <.01). The patient subgroup with mechanical ventilation of greater than 2 days had significantly higher pulmonary vascular resistance at all stages of the study protocol, and in this group there was a correlation of cardiopulmonary bypass time and ventilatory support time (r (2) = 0.48, P <.05).

CONCLUSION

Increased pulmonary vascular resistance, either directly or as a surrogate of the systemic inflammatory response after cardiopulmonary bypass, continues to have a significant effect on postoperative recovery of infants after cardiac operations.

The effect of priming techniques of ultrafiltrators on blood rheology: an in vitro evaluation

The increased interest of using ultrafiltration during cardiopulmonary bypass ICPB) has mandated a re-evaluation of the hematological effects of this blood conservation process. 'Rinse-free' ultrafiltrators can be primed using either crystalloid or blood prior to use. It is unknown whether one priming technique results in superior results in ultrafiltration quality. An in vitro circuit was designed to evaluate the Sorin/COBE HC1400 (n=6), the Lifestream HC70 (n=6), and the Terumo/Sarns HC11 (n=6). All test conditions were conducted at a blood flow rate of 250 ml/min and a transmembrane pressure of 250 mmHg. Samples were drawn and analyzed at four distinct time points for hematocrit, total protein, plasma free hemoglobin, interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNFalpha). The HC11 had significantly greater percent increases in hematocrit under the blood priming protocol (29.2+/-7.9) than either the HC1400 (11.0+/-7.8, p<0.03) or the HC70 (11.9+/-7.8, p<0.04). When crystalloid priming was compared to blood priming, the HC1400 and HC70 produced significant percent increases in hematocrit and total protein levels. The HC1400 devices produced significantly less plasma free hemoglobin when primed with crystalloid rather than blood (43.6+/-38.3 vs 21.3+/-5.6, p<0.01). There were no significant differences between devices or priming techniques for IL-6, IL-8 or TNFalpha levels. In conclusion, the efficiency of the ultrafiltrators was elevated when primed with crystalloid before use. Cytokine levels were relatively unchanged with priming techniques, while plasma free hemoglobin levels were reduced with those devices previously primed with crystalloid.

Essentials of Nitric Oxide for the Pediatric (Cardiac) Anesthesiologist

Short- and long-term survival rates for the operative treat ment of congenital heart disease (CHD) have improved significantly in the past 2 decades. The increasing sophisti cation of the pediatric cardiologist's diagnostic armamen tarium has led to more pervasive use of fetal screening with echocardiography. Early diagnosis and pre-emptive care of the neonate with complex CHD have allowed interventional strategies in the catheterization suite or the operating room to be optimized in both the timing and the quality of pallia tive or corrective procedures. Medications such as prosta glandin E and ventilator strategies using hypoxic and hyper carbic inspired gases exemplify therapies benefitting the contemporary neonate with CHD, often allowing stabiliza tion of the patient before surgery. Surgical care of neonates, infants, and children with CHD has also improved. Insights into maturational differences in myocardial and autonomic function have led to more appropriate myocardial protection strategies and pharmacologic support of the circulation. Recognition of those anomalies in which total correction in the neonate is desirable has stimulated improvements in the technical and cognitive skills of pediatric cardiovascular sur geons and pediatric cardiac anesthesiologists to meet these challenges. The goal of this article is to provide the pediatric anesthesiologist with an overview of inhaled nitric oxide and its relevance to clinical practice.

[Practice Guidelines of the Spanish Society of Cardiology in the postoperative course of congenital heart diseases]

Improvements in myocardial protection, surgical techniques, and perioperative care have made it possible to achieve better prognosis in most congenital heart defects. This requires a coordinated, multidisciplinary approach to patient care, based on the preservation of adequate oxygen delivery to vital organs. It is important to have an understanding of normal postoperative status after cardiac surgery so that abnormal postoperative convalescence can be identified and treated.The causes of abnormal convalescence may be grouped into three categories: a) the pathophysiology of the defect before surgery and the acute changes in physiology that result from surgery; b) the effects of hypothermic cardiopulmonary bypass and deep hypothermic circulatory arrest on organ function, and c) the presence of residual anatomic defects. These conditions may result in prolonged convalescence as well as increased morbidity and mortality. Three primary hemodynamic pathophysiologic disturbances may occur during the postoperative period and lead to abnormal convalescence: left ventricular dysfunction, right ventricular dysfunction and pulmonary hypertension. Though sometimes not directly related to either the cardiac defect or surgery, specific problems involving different organs may alter the normal postoperative period. Neurologic, pneumologic, renal, gastrointestinal and infective complications are discussed separately.

Interventions associated with minimal fontan mortality

BACKGROUND

The operative mortality rate for the first 400 Fontan procedures at this institution was 15% but declined to 4% for the next 100 procedures.

METHODS

The cases of 100 consecutive patients receiving the Fontan procedure and associated with this change in mortality rate were reviewed to determine associations.

RESULTS

The mortality rate in the first and second 50 patients was 16% and 0%, respectively. There were no differences in age, number of risk factors, diagnosis, or operating surgeon between the two groups. Patients in the lower-mortality era were significantly more likely to have had a cavopulmonary anastomosis before a Fontan procedure (90% versus 70%) and to have an extracardiac Fontan procedure (38% versus 8%), shorter cross-clamp (45+/-24 minutes versus 58+/-22 minutes) and cardiopulmonary bypass times (121+/-42 minutes versus 141+/-45 minutes), magnesium-rich cardioplegia (100% versus 39%), hemoconcentration after bypass (67% versus 4%), and institution of pharmacologic support in the operating room.

CONCLUSIONS

Patient characteristics and risk factors were similar in the two groups. However, several interventions that were increasingly utilized in the lower-mortality era, including the extracardiac Fontan procedure and modified ultrafiltration after bypass, are associated with lower mortality. Each one had the potential to improve postoperative myocardial function.

Pediatric cardiac intensive care: current state of the art and beyond the millennium

Pediatric cardiac intensive care has emerged as a distinct clinical entity to meet the unique needs of pediatric patients with congenital and acquired heart disease. This new subspecialty demands expertise and experience in the pediatric subspecialties of cardiology, intensive care, cardiac surgery, cardiac anesthesia, neonatology, and others. Ten recent developments will have an impact on pediatric cardiac intensive care for the coming decades: 1) emergence of new patient populations; 2) new clinical methodologies in the treatment of pulmonary hypertension; 3) innovations in techniques of respiratory support; 4) expanding research of single ventricle physiology; 5) advances in the treatment of heart failure; 6) improved noninvasive imaging; 7) new directions in interventional cardiac catheterization; 8) new techniques in pediatric cardiac surgery; 9) use of computer technology and intensive care monitoring; and 10) appreciation for global economics of intensive care. Finally, a multidisciplinary approach with a team esprit de corps remains vital to a successful pediatric cardiac intensive care program.

Modified ultrafiltration improves carbon dioxide removal after cardiopulmonary bypass in infants

Little is known about the role of modified ultrafiltration in ameliorating the adverse effects of the cardiopulmonary bypass on pulmonary function in infants. Twenty-nine nonrandomized consecutive infants (<12 months of age) who underwent unrestrictive ventricular septal defect closure between 1995 and 1998 were included in this study. Down's syndrome was associated in 9 patients. The actual ventilator settings were highly homogeneous among all patients and each time point in the study. Fourteen infants received modified ultrafiltration after the discontinuation of cardiopulmonary bypass. Fifteen untreated patients served as the control group. Correlates of cardiac and pulmonary functions for both groups were compared. The arterial carbon dioxide tension in the experimental group was significantly lower than in the control group from 20 to 240 min after bypass. Arterial oxygenation and pulmonary arterial pressure were similar in the 2 groups. Modified ultrafiltration improves carbon dioxide removal after cardiopulmonary bypass in infants. This may potentially convey a beneficial impact on hemodynamics.

Endothelins and the lung

Since endothelins were discovered by Yanasigawa in 1988 it has been recognised that they may have an important role in lung pathophysiology. Despite their biological importance as vasoconstrictors the physiological role of endothelin has not yet been defined within the lungs. This review explores their role in acute and chronic disease. During acute inflammation and ischaemia-reperfusion injury cytokines may induce release of endothelin. This is important in the realm of acute lung injury and during surgical procedures such as cardiopulmonary operations including lung resections and transplantation. Complications of surgery including primary organ failure resulting in poor gas exchange as well as increased pulmonary vascular resistance have been linked to the presence of excessive endothelin. Endothelin may have an important role in transplantation biology. The complex process leading to successful lung transplantation includes optimising the donor with brain death, harvesting the lungs, managing acute and chronic rejection, and protecting the vital organs from toxic effects of immunosuppressants. During chronic disease processes, the mitotic action of endothelin may be important in vascular and airway remodelling by means of smooth muscle cell proliferation. We also explore recent advances in drug development, animal models and future directions for research.

Non-renal indications for continuous renal replacement therapy

While there is clear support for the use of continuous renal replacement therapy (CRRT) in critically ill acute renal failure patients, there are other illnesses without renal involvement where CRRT might be of value. These include sepsis and other inflammatory syndromes such as acute respiratory distress syndrome (ARDS) and cardiopulmonary bypass where removal of inflammatory mediators by hemofiltration is hypothesized to improve outcome. Adsorption appears to be the predominant mechanism of mediator elimination. However, the observed hemodynamic improvement can, at least partially, be attributed to a reduction of body temperature or to fluid removal, and the evidence for a clinically important removal of proinflammatory cytokines remains limited. Continuous and therefore smooth fluid removal may improve organ function in ARDS, after surgery with cardiopulmonary bypass, and in patients with refractory congestive heart failure. Continuous removal of endogenous toxins, eventually combined with intermittent hemodialysis, is probably beneficial in inborn errors of metabolism, severe lactic acidosis, or tumor lysis syndrome.

Effect of modified ultrafiltration on plasma thromboxane B2, leukotriene B4, and endothelin-1 in infants undergoing cardiopulmonary bypass

BACKGROUND

Plasma thromboxane B2 (TXB2), leukotriene B4 (LTB4), and endothelin-1 (ET-1) levels increase on cardiopulmonary bypass (CPB). Elevated levels of TXB2 and ET-1 have been correlated with postoperative pulmonary hypertension in infants undergoing repair of congenital heart defects. LTB4 is a potent chemotactic cytokine whose levels correlate with leukocyte-mediated injury. Modified ultrafiltration (MUF) has been associated with improved hemodynamics and pulmonary function, in addition to its beneficial effects on fluid balance and blood conservation. Recent investigations have suggested that removal of cytokines may be the cause of the improved cardiopulmonary function seen with MUF.

METHODS

Plasma TXB2, ET-1, and LTB4 levels were measured in 34 infants undergoing CPB: 22 underwent MUF (group 1), and 12 did not (group 2). Samples were obtained at various time points. All patients underwent conventional ultrafiltration during the rewarming phase of cardiopulmonary bypass.

RESULTS

In group 1, mean end-CPB TXB2 level was 101.2 pg/mL versus 46.9 pg/mL post-MUF (p < 0.05). The mean TXB2 level 1 hour post-CPB (54.1 pg/mL) was not significantly different from the post-MUF level. In group 2, the mean end-CPB TXB2 level was 123.6 pg/mL versus 53.2 pg/mL 1 hour post-CPB. Hence, TXB2 levels decreased by similar amounts and to similar levels by 1 hour post-CPB in both groups. ET-1 levels increased after CPB and were unaffected by MUF: 1.45, 1.80, 2.55 pg/mL at end-CPB, post-MUF, and 1 hour post-CPB, respectively, in group 1; and 1.51, and 2.73 pg/mL at end-CPB and 1 hour post-CPB in group 2. LTB4 levels post-MUF were 119% of pre-MUF values, and were similar at 1 hour post-CPB in both groups.

CONCLUSIONS

Despite reduction in TXB2 by MUF, values were similar and approached baseline 1 hour post-CPB in both groups. LTB4 levels increased slightly with MUF. ET-1 levels increased during and post-CPB and were unaffected by MUF. MUF does not appear to have a significant effect on post-CPB levels of TXB2, ET-1, and LTB4. Therefore, the improved hemodynamics observed with MUF do not appear to be related to removal of these cytokines.

Modified ultrafiltration improves global left ventricular systolic function after open-heart surgery in infants and children

OBJECTIVES

Modified ultrafiltration increases blood pressure and cardiac index following open-heart surgery in children, but it is unclear if this is secondary to an improvement in global left ventricular function. A previous report has suggested that left ventricular systolic function as assessed in a single chord is improved by ultrafiltration (Davies MJ, Nguyen K, Gaynor JW, Elliott MJ. Modified ultrafiltration improves left ventricular systolic function in infants after cardiopulmonary bypass. J Thorac Cardiovasc Surg 1998;115:361--370). The prominent vascular actions of modified ultrafiltration necessitate left ventricular assessment using load-independent indices of systolic and diastolic function.

METHODS

In 22 consecutive infants and children undergoing open-heart surgery, left ventricular function was assessed following bypass and then 10 min later. Sixteen children (median weight 8.1 kg) underwent modified ultrafiltration during this period, the remainder (median weight 7.3 kg) were controls for spontaneous recovery without ultrafiltration. Real-time pressure-volume loops, with transient inferior caval vein snaring were generated from conductance and microtip pressure catheters inserted through the LV apex. From these, load-independent (slope of the end-systolic pressure-volume [Ees] and end-diastolic pressure-volume [Eed] relationships) and load-dependent (Pmax, maximum LV pressure; Ped, end-diastolic LV pressure; maximum [dP/dtmax] and minimum [dP/dtmax] time derivatives of LV pressure; tau, time constant of isovolumic relaxation) indices of left ventricular function were measured.

RESULTS

Haemoconcentration was achieved in all modified ultrafiltration patients, median increase in haematocrit 34% (interquartile range 21%, 42%), final haematocrit 0.40 (0.35, 0.41). Ees increased 58% (9, 159, P = 0.005). The changes in Eed, Pmax, Ped, dP/dtmax, dP/dtmin, and tau were not significantly different from the control group.

CONCLUSION

Modified ultrafiltration improves global left ventricular systolic function in infants and children following open-heart surgery.

Effect of modified ultrafiltration in high-risk patients undergoing operations for congenital heart disease

BACKGROUND

Modified ultrafiltration (MUF) after cardiopulmonary bypass (CPB) in children decreases body water, removes inflammatory mediators, improves hemodynamics, and decreases transfusion requirements. The optimal target population for MUF needs to be defined. This prospective, randomized study attempted to identify the best candidates for MUF during operations for congenital heart disease.

METHODS

Informed consent was obtained from 100 consecutive patients with complex congenital heart disease undergoing operations with CPB. They were randomized into a control group (n = 50) of conventional ultrafiltration during bypass and an experimental group using dilutional ultrafiltration during bypass and venovenous modified ultrafiltration after bypass (MUF group, n = 50). Postoperative arterial oxygenation, duration of ventilatory support, transfusion requirements, hematocrit, chest tube output, and time to chest tube removal were compared between the groups stratified by age and weight, CPB technique, existence of preoperative pulmonary hypertension, and diagnosis.

RESULTS

There were no MUF-related complications. In patients with preoperative pulmonary hypertension, MUF significantly improved postoperative oxygenation (445 +/- 129 mm Hg versus control: 307 +/- 113 mm Hg, p = 0.002), shortened ventilatory support (42.9 +/- 29.5 hours versus control: 162.4 +/- 131.2 hours, p = 0.0005), decreased blood transfusion (red blood cells: 16.2 +/- 18.2 mL/kg versus control: 41.4 +/- 27.8 mL/kg, p = 0.01; coagulation factors: 5.3. +/- 6.9 mL/kg versus control: 32.3 +/- 15.5 mL/kg, p = 0.01), and led to earlier chest tube removal. In neonates (< or =30 days), MUF significantly reduced transfusion of coagulation factors (5.4 +/- 5.0 mL/kg versus control: 39.9 +/- 25.8 mL/kg, p = 0.007), and duration of ventilatory support (59.3 +/- 36.2 hours versus 242.1 +/- 143.1 hours, p = 0.0009). In patients with prolonged CPB (>120 minutes), MUF significantly reduced the duration of ventilatory support (44.7 +/- 37.0 hours versus 128.7 +/- 133.4 hours, p = 0.002). No significant differences were observed between MUF and control patients for any parameter in the presence of ventricular septal defect without pulmonary hypertension, tetralogy of Fallot, or aortic stenosis.

CONCLUSIONS

Modified ultrafiltration after CPB is safe and decreases the need for homologous blood transfusion, the duration of ventilatory support, and chest tube placement in selected patients with complex congenital heart disease. The optimal use of MUF includes patients with preoperative pulmonary hypertension, neonates, and patients who require prolonged CPB.