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Asian Cardiovasc Thorac Ann 2006;14:341-350
© 2006 Asia Publishing EXchange Ltd

REVIEW PAPER

Impact of Modified Ultrafiltration on Morbidity After Pediatric Cardiac Surgery

Shahzad G Raja, MRCS, Shaik Yousufuddin, MBBS, Faisal Rasool, MBBS, Ayo Nubi, MBBS, Mark Danton, FRCS, James Pollock, FRCS

Department of Cardiac Surgery, Royal Hospital for Sick Children, Glasgow, United Kingdom

For reprint information contact: Shahzad G Raja, MRCS Tel: 44 141 201 0269 Fax: 44 141 201 9204 Email: drrajashahzad{at}hotmail.com, Department of Cardiac Surgery, Royal Hospital for Sick Children, Yorkhill NHS Trust, Dalnair Street, Glasgow G3 8SJ, United Kingdom.


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 CONCLUSION
 REFERENCES
 
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.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
CONCLUSION
 REFERENCES
 
Cardiopulmonary bypass (CPB) is an essential prerequisite for undertaking corrective cardiac surgery for complex congenital cardiac defects.1 The advantages of a motionless and bloodless field, however, are undermined by a large number of risks secondary to initiation of the systemic inflammatory response syndrome.1 Many consequences of extracorporeal circulation have been implicated in the genesis of the systemic inflammatory state, including exposure of blood components to synthetic surfaces, the fluid overload necessary for priming the circuit, body temperature changes, non-pulsatile flow, ischemia, and reperfusion of end organs.2–3 It is currently believed that cellular and humoral factors including cytokines are activated during bypass, which mediate organ damage.3–4 The clinical manifestations of the systemic inflammatory response syndrome include cardiac, respiratory, renal, hepatic, and neurological dysfunction, bleeding diathesis, and even multisystem organ failure.3–4

Among the therapeutic maneuvers proposed to mitigate the consequences of postperfusion syndrome, modified ultrafiltration (MUF) has recently come into favor. The technique pioneered by Naik and colleagues5–7 at the Hospital for Sick Children (Great Ormond Street) in London, entails removal of water and low-molecular-weight substances under a hydrostatic pressure gradient after separation from CPB. This method has been demonstrated to induce hemoconcentration and reduce bleeding and total body water accumulation in children.8 As modified ultrafiltration counteracts tissue edema and eliminates inflammatory mediators, it has been attributed by further observations with an ability to improve postperfusion end-organ function and to attenuate morbidity after pediatric cardiac operations.9–15 This review attempts to evaluate currently available evidence on the impact of MUF on organ function and morbidity after pediatric cardiac surgery.

TECHNIQUE OF MODIFIED ULTRAFILTRATION
In the MUF technique described by Naik and colleagues,5,7 the ultrafilter is placed with its inlet connected to the arterial line and its outlet to the venous line of the CPB circuit. The CPB circuit, including the ultrafilter, is then primed. During CPB, the inlet of the filter is kept clamped. When the patient is weaned from CPB, the outlet of the ultrafilter is fed into the right atrium via a Hot Line L70 (Level 1 Technologies, Rockland, MA, USA). The venous blood is chased back to the venous reservoir with saline solution. The inlet of the ultrafilter is declamped and arteriovenous ultrafiltration is carried out. Blood flow through the ultrafilter is maintained at approximately 200 mL·min–1 by a roller pump on the inlet. Suction is applied to the filter port (–125 mm Hg) to achieve an ultrafiltration rate of 100 to 150 mL·min–1. A constant left atrial pressure is maintained by giving volume from the venous reservoir back to the patient via the ultrafilter, thus hemoconcentrating the fluid in the circuit.

SEARCH METHODOLOGY
The English language scientific literature was reviewed primarily by searching MEDLINE from 1966 through June 2004, using the PubMed interface.16 Keywords used in the search included modified ultrafiltration, ultrafiltration, cardiopulmonary bypass, extracorporeal circulation, pediatric cardiac surgery, congenital cardiac surgery, congenital heart surgery, congenital heart disease, complications, and morbidity. The "Related Articles" function was used to broaden the search, and all abstracts, studies, and citations scanned were reviewed. The reference lists of articles found through these searches were also reviewed for relevant articles. In addition, links on web sites containing published articles were searched for relevant information. The authors of this article chose studies relevant to the topic. The search was carried out in stages so as to achieve a search strategy with high sensitivity (highest likelihood of retrieving all relevant papers). Similar search terms were combined using the Boolean operator ‘OR’ to find all abstracts that contained information about a particular search term. These individual terms were then combined using the Boolean operator ‘AND’ to find papers that contained information on all the search terms. This is a well-recognized method for performing sensitive searches, which has been described in detail in the British Medical Journal.17 The papers found by the search strategy were then appraised in a structured format, using critical appraisal checklists. These are widely available in several formats and aid in assessing the paper for methodological and analytical soundness and help to uncover any significant methodological flaws.18 In addition, after appraisal, the paper was categorized in terms of the type of study and the level of evidence presented.19 The levels of evidence are listed in Table 1Go, and enable readers to come to a conclusion about the certainty to which evidence exists on the topic.


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  		Table 1. Levels of Evidence
 
TOTAL BODY WATER AND MUF
In children, CPB is associated with the accumulation of water as a consequence of an inflammatory capillary leak.2 An increase in total body water (TBW) of 11% to 18% is usually seen after CPB.5,8,20–21 Young age, hypothermia, hemodilution, and long duration of bypass have been shown to be incremental risk factors for the accumulation of water.20 This increase in TBW is associated with tissue edema and subsequent organ dysfunction, particularly of the heart, lungs, and brain. The most important effect of MUF is reduction of TBW. There is a marked reduction in the accumulation of TBW after CPB with MUF (4% increase) compared to controls (18% increase) or conventional ultrafiltration (CUF; 15% increase).5,7,8,21 This reduction of TBW results in an increase in hematocrit to pre-bypass levels, which translates into improved organ function and decreased morbidity post-CPB.5,8,22–25

CARDIOVASCULAR FUNCTION AND MUF
Cardiopulmonary bypass is an unnatural condition leading to changes that may result in unfavorable hemodynamics. Myocardial thickness and contractility are altered to the detriment of the patient. The activated leukocytes due to contact of blood with foreign material in the form of tubing and pumps release a variety of cytotoxic products such as lysosomal hydrolases, neutral proteases, and arachidonic acid, some of which have been shown to increase vascular permeability.22 During controlled hypothermic cardiac arrest, there may be impairment of the transmembrane fluid transport due to hypothermia which also predisposes the heart to further fluid accumulation. Furthermore, ischemia has been shown to predispose the myocardium to pathologic fluid accumulation after restoration of coronary flow.26 In addition, several substances such as endothelin-1 (ET-1) which are vasoactive, cardioactive, or both have been found to be elevated following CPB.27

Several studies have shown an improvement in hemodynamic parameters after MUF (Table 2Go).8,12,14,28–31 Naik and colleagues28 measured heart rate, blood pressure, left and right atrial pressures, pulmonary artery pressure, and cardiac output before and after MUF. With the left atrial pressure constant, MUF produced a decrease in heart rate, an increase in systolic pressure, an improvement in cardiac index, no change in systemic vascular resistance, and a dramatic reduction in pulmonary vascular resistance. Measurements recorded at hematocrits of 25% and 30% showed linear improvements in these measured parameters. They also noticed that the heart became visibly smaller during MUF. They believed that this might be due to a simultaneous reduction in pulmonary vascular resistance and myocardial water content.12 A study by Hodges and colleagues29 also confirmed a rise in systemic arterial pressure and cardiac index after MUF, and they also showed that this was not associated with a change in depth of anesthesia as plasma fentanyl levels remained within the high therapeutic range throughout the period of ultrafiltration. Davies and colleagues12 demonstrated that the hemodynamic improvements seen after MUF are associated with an increase in intrinsic left ventricular systolic function. The increase in end-diastolic length and fall in end-diastolic pressure seen after MUF was considered to be consistent with an improvement in left ventricular compliance resulting from a reduction in myocardial edema. Gaynor and colleagues30 also confirmed the reduction in myocardial cross-sectional area after MUF. This improvement in left ventricular function leads to decreased inotropic requirements in the first 24 hours after the operation.32


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  		Table 2. Impact of Modified Ultrafiltration on Cardiovascular Function
 
PULMONARY FUNCTION AND MUF
Pulmonary injury after cardiac surgery is one of the complications of CPB, with a high incidence among infants and younger patients with severe pulmonary hypertension (PH).33 After CPB, various degrees of pulmonary dysfunction occur which are manifested by lower pulmonary compliance, higher pulmonary resistance, and poor alveolar gas exchange. Sometimes, severe acute pulmonary dysfunction will lead to death.34–35 Several factors may contribute to such pulmonary problems. Hemodilution lowers serum albumin concentration and colloid osmotic pressure and increases the effective capillary filtration pressure, leading to the accumulation of plasma water in the interstitial space, which decreases pulmonary compliance and impairs air exchange across the respiratory membrane. Additionally, when the aorta and vena cava are crossclamped, the lung is ischemic and metabolic products accumulate in the interstitial fluid of the lung. After the crossclamp is released, oxygenated blood perfuses the lung again and produces oxygen free radicals, leading to ischemia-reperfusion damage of the lung. Furthermore, hypothermia, contact of blood with the bypass circuit, and hemodynamic changes all promote the production and release of inflammatory mediators which cause a systemic inflammatory response that results in further pulmonary damage.33–35

A large number of randomized controlled trials and retrospective studies have shown important pulmonary benefits of MUF (Table 3Go).13,15,36–44 Bando and colleagues13 in their randomized controlled trial of 100 consecutive patients with complex congenital heart disease undergoing operations with CPB, showed that in patients with preoperative PH, MUF significantly improved postoperative oxygenation (445 ± 129 vs. 307 ± 113 mm Hg in controls, p = 0.002), shortened ventilatory support (42.9 ± 29.5 vs. 162.4 ± 131.2 hours, p = 0.0005), decreased blood transfusion (red blood cells: 16.2 ± 18.2 vs. 41.4 ± 27.8 mL·kg–1, p = 0.01; coagulation factors: 5.3. ± 6.9 vs. 32.3 ± 15.5 mL·kg–1, p = 0.01), and led to earlier chest tube removal. In neonates (≤30 days), MUF significantly reduced transfusion of coagulation factors (5.4 ± 5.0 vs. 39.9 ± 25.8 mL·kg–1, p = 0.007), and duration of ventilatory support (59.3 ± 36.2 vs. 242.1 ± 143.1 hours, p = 0.0009). In patients with prolonged CPB (> 120 min), MUF significantly reduced the duration of ventilatory support (44.7 ± 37.0 vs. 128.7 ± 133.4 hours, p = 0.002). In another study, the same group reported important pulmonary benefits of MUF in patients with preoperative PH.36 They demonstrated that combined dilutional ultrafiltration (DUF) and MUF efficiently removed free water (170.0 ± 43.1 mL·kg–1) compared with CUF (20.6 ±8.2mL·kg–1).Thistechniquealsoremovedasignificant amount of the circulating ET-1 (1.81 ± 0.86 pg·mL–1 in the DUF ultrafiltrate, 6.44 ± 1.82 pg·mL–1 in the MUF filtrate) and maintained significantly lower plasma ET-1 levels compared with the control group. Subsequently, the systolic pulmonary/systemic pressure ratio in the DUF/MUF group was significantly lower compared to the control group at 12 hours postoperatively. As a result, 3 of 12 control patients (25%), but none of the DUF/MUF patients had a pulmonary hypertensive crisis after CPB. Moreover, perhaps as a result of the reduced systolic pulmonary/systemic pressure ratio, patients treated with DUF/MUF required significantly less ventilatory support.


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  		Table 3. Impact of Modified Ultrafiltration on Pulmonary Function
 
Modified ultrafiltration causes a reduction in lung water. This is associated with improved lung compliance and decreased airway pressures after congenital heart surgery.32 Dynamic pulmonary compliance, which is decreased after CPB, is reversed after MUF.43 This improvement in dynamic compliance results in lower mean airway pressure, which may further reduce the impact of mechanical ventilation. Kameyama and colleagues44 in their retrospective analysis showed that in patients under 20 kg in weight who underwent corrective open heart operations, MUF resulted in significantly shorter intubation time and better respiratory index. Multivariate analysis of their data revealed that the enforcement of MUF was an independent correlate of postoperative respiratory index. Reduced incidence of pleural and pericardial effusions, decreased pulmonary vascular resistance, increased arterial oxygen, enhanced carbon dioxide removal, and shorter intensive care unit stay are some of the other benefits of MUF.8,10,22,37,39,42

COAGULATION AND MUF
Coagulopathy after CPB is a well-recognized problem. Several factors, both patient- and procedure-related, have been shown to contribute to this problem.45–47 A number of authors have reported that MUF significantly attenuates the dilutional coagulopathy associated with CPB in infants undergoing pediatric cardiac surgery (Table 4Go).24,48–50 In a prospective study to quantify the effects of MUF on coagulation factors in pediatric patients, Ootaki and colleagues48 studied 7 children scheduled to undergo open heart surgery for congenital heart defects. They showed that MUF was associated with significant increases in hematocrit (17.6% ± 1.6% to 21.6% ± 2.4%), platelet count (11.1 ± 2.5 to 12.8 ± 2.4 x 104/mm3), total plasma protein (2.7 ± 0.3 to 3.4 ± 0.4 g·dL–1), and albumin (1.6 ± 0.2 to 2.1 ± 0.2 g·dL–1). Fibrinogen, prothrombin, and factor VII also increased significantly during MUF, but factor IX and factor X did not change. Friesen and colleagues24 have also shown that MUF is a better technique for increasing concentrations of fibrinogen and coagulation factors. In their prospective study of 20 consecutive patients weighing less than 15 kg, who underwent open heart surgery for repair of a variety of congenital heart defects, they observed an absolute increase in fibrinogen concentration (mean, 36 mg·dL–1) and an approximately 80% increase in plasma protein concentration associated with MUF. Platelet count, which was significantly lower than baseline at the conclusion of CPB, was not significantly affected by MUF. Furthermore, improvement in hematocrit is a consistent effect of MUF and indicates the hemoconcentrating efficacy of the technique.5,22–25


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  		Table 4. Impact of Modified Ultrafiltration on Coagulation
 
TRANSFUSION REQUIREMENTS AND MUF
Hemostatic changes induced by CPB are one of the major factors responsible for increased postoperative blood loss and requirement for transfusion. The reasons for hemostatic abnormalities after CPB are multifactorial. Coagulation factors are decreased, the platelet function and number is reduced, and an imbalance of the coagulation and fibrinolytic systems occurs.51–54 Various pharmacological and non-pharmacological strategies have been introduced to reduce the consequences of CPB-induced hemostatic changes.55–60 In pediatric cardiac surgery, MUF improves hemostasis after CPB with beneficial effects on postoperative bleeding, chest drainage, and the need for blood transfusion (Table 5Go).5,8,13,24,25,49,61 Requirements for red blood cells and coagulation factors (fresh frozen plasma, platelets, and cryoprecipitates) are significantly lower in MUF patients compared with controls in neonates, as well as those groups of patients with preoperative PH or prolonged CPB.13 In both moderate- and deep-hypothermia patients, MUF significantly reduces the requirement for blood transfusion.13 Hemoconcentration with attenuation of dilutional coagulopathy is the most likely mechanism for improved hemostasis and reduced transfusion requirements after MUF.7,48


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  		Table 5. Impact of Modified Ultrafiltration on Transfusion Requirements
 
SYSTEMIC INFLAMMATORY RESPONSE AND MUF
The combination of anesthesia, surgical stress, and CPB evokes an acute systemic inflammatory response with activation of the complement and coagulation systems, stimulation of cytokine production, cellular entrapment in organs, neutrophil activation with degranulation, platelet activation, and endothelial dysfunction.62 Cardiopulmonary bypass is a potent stimulus for the release of proinflammatory cytokines, including tumor necrosis factor-{alpha}, interleukin-1, interleukin-6 (IL-6), and interleukin-8.63 These proinflammatory cytokines play an important role in the systemic inflammatory response syndrome or postpump syndrome.64 The impact of MUF on the systemic inflammatory response is controversial.7 Several randomized and non-randomized studies with conflicting results have been published (Table 6Go).33,39,65–73 To determine the ability of ultrafiltration to remove harmful medium-sized solutes produced in CPB, Huang and colleagues33 selectively measured IL-6, thromboxane B2, and ET-1 at various points. The results of their study showed that whereas serum IL-6 levels were significantly lower after MUF, the effect on thromboxane B2 removal was mild, and ET-1 levels were unaffected. On the contrary, Bando and colleagues36 in their prospective randomized controlled study observed that ET-1 levels were significantly lower after MUF and the ultrafiltrates contained significant amounts of ET-1 (1.81 ± 0.86 pg·mL–1 for DUF, and 6.44 ± 1.82 pg·mL–1 for MUF). In a single-arm prospective observational study, Yndgaard and colleagues74 measured the amount of endotoxins in plasma during CPB and before and after MUF in 20 children undergoing corrective cardiac surgery for various congenital cardiac defects. The results of their study showed that after termination of CPB, MUF lowered the amount of circulating endotoxins in blood from a median of 24.2 ng (range, 2.1–75.4 ng) to 9.0 ng (range, 0.1–40.6 ng), and the major bulk of this endotoxin load was retrieved in the ultrafiltrate (median, 11.9 ng; range, 0–12.1 ng). However, at present there are no studies correlating cytokine removal with improvement in any measure of organ function.


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  		Table 6. Impact of Modified Ultrafiltration on Systemic Inflammation
 
IMPACT OF ULTRAFILTRATION TECHNIQUES DURING CPB ON EFFICACY OF MUF
Apart from MUF alone, techniques of DUF and zero-balance ultrafiltration (Z-BUF) have been combined with MUF to enhance its efficacy. In the DUF method, the patient-CPB circuit is actively exchanged by setting the circuit parameters to allow ultrafiltrate formation at a rate equivalent to the crystalloid cardioplegia volume plus 40 to 70 mL·kg–1·h–1, and adding small aliquots of diluent (Plasmalyte A < 20 mL·kg–1) as necessary to maintain a safe blood level in the venous reservoir of the CPB circuit. The DUF is carried out semi-continuously throughout the CPB run and is interrupted during weaning from CPB while inotropic or vasoactive drugs are being administered.36 On the other hand, the technique of Z-BUF involves an isovolumetric exchange of fluid, typically Normasol, congruent with the amount of ultrafiltrate removed. Unlike DUF, Z-BUF is performed only during the rewarming phase of CPB.36,67 Current evidence from most studies suggests that the combination of DUF and Z-BUF with MUF can effectively concentrate blood, exclude harmful inflammatory mediators and attenuate lung edema and inflammatory pulmonary injury.36,39,40,67,75,76

IMPACT OF DIFFERENT FILTER SYSTEMS ON EFFICACY OF MUF AND CLINICAL OUTCOMES
To date, only one study has been carried out to assess whether different filter types influence the efficacy of MUF and clinical outcomes. Berdat and colleagues77 prospectively randomized 41 children < 5 years old undergoing pediatric cardiac surgery to four groups: group A (polyamide filter with conventional ultrafiltration), group B (polyamide filter with modified ultrafiltration), group C (polysulfone filter with conventional ultrafiltration), and group D (polysulfone filter with modified ultrafiltration). They measured IL-6, IL-10, tumor necrosis factor, terminal complement complex, and lactoferrin before the operation, before rewarming, after ultrafiltration, at 6 and 18 hours after the operation, and in the ultrafiltrate. Clinical outcomes for the groups were also recorded. The results revealed that the polysulfone filter had a filtration profile for inflammatory mediators superior to that of the polyamide filter, in respect of IL-6, tumor necrosis factor, and IL-10. Interleukin 6 was most efficiently removed by conventional ultrafiltration with a polysulfone filter, and tumor necrosis factor was most effectively removed by MUF with a polysulfone filter, whereas other inflammatory mediators were not influenced by filter type or ultrafiltration method. Interestingly, clinical outcomes were similar in all groups and not influenced by type of filter or ultrafiltration strategy. Based on these findings, the authors recommended that combined conventional and modified ultrafiltration with a polysulfone filter may be the most effective strategy for removing inflammatory mediators in pediatric heart surgery.

IMPACT OF VOLUME OF FILTRATE HARVESTED DURING MUF ON CLINICAL OUTCOMES
The positive benefits of MUF are thought to correlate with the volume of filtrate removed.78 In a carefully designed prospective randomized study, Daggett and colleagues11 evaluated the effectiveness of no ultrafiltration, CUF, and MUF in preventing tissue edema and organ dysfunction using a neonatal swine model of CPB. MUF was more effective in preventing accumulation of TBW and myocardial edema. The significantly greater removal of volume of filtrate translated into a significant improvement in left ventricular contractility assessed by the preload-recruitable stroke-work index. Thompson and colleagues79 conducted a prospective randomized study to test the hypothesis that MUF and CUF have similar clinical effects when a standardized volume of fluid is removed. The results of their study supported this hypothesis. Interestingly, a corollary of their conclusion is that MUF is more effective than CUF because a greater volume of filtrate can be removed.

CONTROVERSIES, COMPLICATIONS, AND CONCERNS
The mechanisms by which MUF produces beneficial effects have not been fully elucidated. Potential mechanisms include reduction of tissue edema, hemoconcentration, and removal of inflammatory mediators.78 Although it is tempting to speculate that removal of the inflammatory mediators diminishes the inflammatory response to CPB, thus ameliorating some of the adverse sequelae, no study has yet established a definite relationship between removal of inflammatory mediators and improved outcome. There is also a view that as MUF is performed while blood is at body temperature and circulating normally through the heart and lungs, activated leukocytes are absorbed by the lungs, resulting in diminished inflammatory process in the heart and other organs.11 In addition, there has been significant variability in the criteria chosen for termination of MUF. Darling and colleagues80 in their survey of 22 North American pediatric open-heart centers using the MUF technique revealed that 10 continued MUF until the circuit contents were completely salvaged, 5 used a time-based criterion, 1 used a hematocrit endpoint, 1 used a filtrate-volume endpoint, and 5 used other endpoints.

Concerns have also been raised about potential risks and complications of MUF. It is extremely important to realize that the procedure is not risk free.1 A survey of 22 centers revealed that technical complications directly related to the technique occurred in 82% of these centers.80 The most common reported complication is air cavitating out of solution in the arterial line.80 Other complications include patient cooling during MUF, circuit over-pressurization and disruption due to a clamped line, accidental cardioplegia solution infusion when using a blood cardioplegia system, a clotted MUF circuit, transient patient exsanguinations due to an un-clamped oxygenator recirculation line during MUF, hypotension and neurological deficits if the blood flow through the system is too high, causing a decrease in blood flow to the brain.1,80 A variety of safety devices or modifications for MUF have been adopted to prevent these complications: negative pressure servo-regulation, additional perfusionist in the room, extra-vigilant arterial line pressure monitoring, bypass arterial line filter, inversion of the hemoconcentrator, addition of a bubble trap to the MUF circuit, changing the position of the bubble detector, pre-warming the hemoconcentrator, addition of a heat exchanger to the MUF circuit, using a heating transfusion line for the MUF circuit, adjusting operating room temperature to very warm, using a positive-pressure servo-regulated MUF pump, using an ultrasonic flowmeter, placement of an inline hematocrit sensor, and a venovenous ultrafiltration technique.31,80

Several other concerns and counter-arguments have also been raised about MUF in the available literature. Hemofilters are themselves plastic nonendothelial surfaces that induce the release of cytokines.81 In addition, MUF could also alter levels of medication such as fentanyl, midazolam, alfentanil, heparin and aprotinin.29,67,82–83 Finally, there is criticism about the additional cost of adding a MUF circuit to CPB. It is argued that the MUF circuit alone increases the cost of the CPB circuit by US$100, and the additional 15 to 20 minutes spent in the operating room while the patient is undergoing MUF further increases costs.81


   CONCLUSION
TOP
 ABSTRACT
 INTRODUCTION
 CONCLUSION
REFERENCES
 
Pediatric patients, especially those who are small, hemodiluted, and cooled, or who experience long CPB times, are at increased risk of developing multi-organ dysfunction with devastating consequences. An unbiased analysis of available evidence from several randomized controlled trials as well as retrospective studies shows that MUF results in a reduction of excess TBW accumulation with improvement in cardiac and pulmonary function after CPB in infants and children in the early postoperative period. It also results in correction of dilutional coagulopathy and modification of the systemic inflammatory response. All this contributes to improved hemostasis, leading to reduced postoperative blood loss and requirement for transfusion. A cumulative effect of these benefits is reduced morbidity after pediatric cardiac surgery in the early postoperative period. However, evidence that the use of modified ultrafiltration significantly reduces the duration of hospitalization or mortality following pediatric cardiac surgery, or results in an improved long-term outcome is lacking at present.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 CONCLUSION
 REFERENCES
 

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