Is prophylactic haemofiltration during cardiopulmonary bypass of benefit during cardiac surgery?
Date First Published:
November 27, 2002
Last Updated:
January 13, 2004
Report by:
Joel Dunning, RCS Research Fellow (Manchester Royal Infirmary)
Search checked by:
Satish Das, Manchester Royal Infirmary
Three-Part Question:
In [patients undergoing elective Cardiac Surgery] does [prophylactic Haemofiltration] improve [survival or time to discharge or days in CSU]?
Clinical Scenario:
You are performing a difficult aortic valve replacement in an 80-year-old patient that also requires three coronary grafts and has an ejection fraction of only 35%. You know that the bypass time is going to be long. The perfusionist informs you that in the last institution he worked at, every patient was prophylactically haemofiltered if bypass was used and that this reduced inflammatory mediators and improved outcome. You decide to use a haemofilter in this high risk case but resolve to look up the evidence for this after the case.
Search Strategy:
Medline 1966-07/03 using the OVID interface.
Search Details:
[(exp hemofiltration/ OR hemofiltration.mp OR haemofiltration.mp OR ultrafiltration.mp) AND (exp thoracic surgery/ or thoracic surgery.mp or cardiac surgery.mp or CABG.mp OR exp Cardiopulmonary Bypass/ OR Cardiopulmonary bypass.mp] LIMIT to Human and English
Outcome:
273 papers were found of which 9 were deemed to be relevant.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Hemofiltration during cardiopulmonary bypass: the effect on anti-Xa and anti-IIa heparin activity. Despotis GJ, Levine V, Filos KS, et al. 1997, USA | 20 patients undergoing CABG Investigated how haemofiltration effects heparin level variability and whether it filters the low molecular weight fraction Heparin measured indirectly using anti-Xa and anti-II.a assays |
Case Series (4) | Levels of heparin activity | Pre haemofiltration anti-Xa heparin activity was 3.9 +/- 1.7 U/ml<br><br>Post haemofiltration Anti-Xa heparin activity was 5+/-1.8 U/ml P=0.003<br><br>Haemofiltration increases heparin concentration and contributes to variability<br><br>HF does not filter out low molecular weight heparin into ultrafiltrate | Small study. Main finding is that low molecular weight heparin is NOT filtered out They then report their positive secondary finding which seems to have C.I.s that cross |
| Conventional haemofiltration during routine coronary bypass surgery [erratum appears in Perfusion Nov;12(6):347]. Babka RM, Petress J, Briggs R, et al. 1997, USA | 60 patients undergoing CBP Ultrafiltration group: n=30, ultrafiltration with CPB control group n=30 standard CPB |
Prospective case – control trial (3b) | Physiological parameters | No difference in blood loss, blood transfused, length of stay or cost of patient<br><br>Significant difference in post op weight gain (3.5 Vs 4.8 lbs) and mean ultrafiltrate vol was 2510ml | Ultrafiltration was of little clinical value Controls had a significantly longer Xclamp time (32 vs 38mins) No power studies given for null findings |
| Influence of combined zero-balanced and modified ultrafiltration on the systemic inflammatory response during coronary artery bypass grafting. Tassani P, Richter JA, Eising GP, et al. 1999, Germany | 43 patients having elective CABG Modified ultrafiltration group: n=21- zero fluid balance maintained Control group : n=22 |
PRCT (1b) | Immune mediator levels | IL-6 and IL-8 significantly lower levels in the Ultrafiltration group immediately post CPB<br><br>These levels were not significantly different at 2 and 4 hours<br><br>No difference in IL-10 and IL-1 levels | There was a short difference in inflammatory mediators that disappeared after 2 hours |
| Effects of hemofiltration on serum aprotinin levels in patients undergoing cardiopulmonary bypass. Van Norman GA, Patel MA, Chandler W et al. 2000, USA | 2 groups of patients randomised to haemofiltration or no haemofiltration during cardiopulmonary bypass | PRCT (1b) | Aprotinin levels | No difference in aprotinin levels in the two groups | Haematocrit improved with haemofiltration |
| Haematocrit | Significantly higher haematocrit levels in the haemofiltration group | ||||
| Modified ultrafiltration lowers adhesion molecule and cytokine levels after cardiopulmonary bypass without clinical relevance in adults. Grunenfelder J, Zund G, Schoeberlein A, et al. 2000, Switzerland | 97 patients undergoing CABG with CPB MUF group, n=60, Modified ultrafiltration for 15mins on CPB Control group, n=37, CPB only Stratified study as 2 groups also subdivided into Normo thermic and Hypothermic CPB. Hypothermic patients had temp 26-28 C on CPB |
PRCT (2b) | Immune mediators | MUF led to a significantly lower level of cytokines IL-6, IL-8, TNF and IL2R) and adhesion molecules<br><br>Normothermia also led to a similar reduction | No clinical differences found Roller pump used for CPB Underpowered to make conclusions regarding mortality or morbidity |
| Clinical outcome | No difference in time to discharge or mortality/morbidity between the filtered and unfiltered groups | ||||
| The effects of modified hemofiltration on inflammatory mediators and cardiac performance in coronary artery bypass grafting. Boga M, Islamoglu, Badak I, et al. 2000, Turkey | 40 CABG adult patients Control, n=20, standard CPB Treatment, n=20, modified haemofiltration for 20 mins on rewarming at the end of CPB |
PRCT (1b) | Haemodynamic parameters | Immediately postoperatively CI and SVR both higher in filtered group. These differences quickly became non significant<br><br>Haematocrit was higher (0.33 vs 0.29 ) and blood transfusion needs also significantly lower 0.83 vs 1.84 in the HF group, P<0.05 | Small study but did find significant improvements in post op blood loss and CI post op |
| Hemodynamic and echocardiographic effects of hemofiltration performed during cardiopulmonary bypass. Blanchard N, Toque Y, Trojette F, et al. 2000, France | 2 groups of CABG patients, Control, N=13, standard rewarming and CPB Treatment, N=13, Haemofiltration on rewarming on Cardio Pulmonary Bypass. 15ml/kg filtered Haemodynamic and echogardiographic parameters measured on completion of rewarming |
Single blind PRCT (1b) | Haemodynamic parameters | Treatment: No change in SVR or CI<br><br>Control : Significant drop in SVR and rise in HR and CI | |
| Echocardiographic parameters | Significantly improved kinetic score in treatment group compared to the control group | ||||
| Modified ultrafiltration removes serum interleukin-8 in adult cardiac surgery. Onoe M, Magara T, Yamamoto Y, et al. 2001, Japan | 18 patients undergoing cardiac surgery Treatment: 9 patients had CPB and standard ultrafiltration followed by MUF on rewarming Control: 9 controls had CPB only Serum IL-8 measured immediately after CPB and 3h after CPB (IL-8 is a cytokine which strongly promotes neutrophil degranulation and infiltration) |
PRCT (2b) | Serum Levels of IL-8 | Treatment group: IL-8 reduced from 69.5=/-33 to 58.9+/-32 after ultrafiltration instituted<br>P=0.0029 | IL-8 level is reduced by a little and the haematocrit is increased But all findings have v.wide confidence intervals, all of which seem to cross on the graphical images of their results Trend towards higher BP also reported but NS |
| Haematocrit | Treatment group: Haematocrit increased from mean 21 to 24 P=0.0008<br>Control: No change in haematocrit | ||||
| Influence of modified ultrafiltration on coagulation, fibrinolysis and blood loss in adult cardiac surgery. Leyh RG, Bartels C, Joubert-Hubner E, et al. 2001 Germany | 48 patients undergoing myocardial revascularisation randomised to: Conventional Ultrafiltration CUF (n=16) Modified ultrafiltration MUF (n=16) Control group (n=16) |
PRCT (1b) | Post-op transfusion volume | MUF 2.0ml/kg bw<br>CUF 6.9ml/kg bw<br>Control 7.0ml/kg bw<br>P=0.029 | This study finds that there is less blood loss and need for transfusion with MUF but not CUF Small study Roller pump CPB used |
| Post-op blood loss | MUF 6.4 ml/kg bw in 24hrs<br>CUF 9.2 ml/kg bw in 24hrs<br>Control 8.9 ml/kg bw in 24hrs<br>P=0.008 | ||||
| Other | No difference in levels of any clotting or fibrinolytic system markers, including ACT, PT, APTT, fibrinogen, platelet count |
Author Commentary:
It is noted that modified haemofiltration (MUF) is the technique of performing haemofiltration for 10-20mins at the end of bypass, during rewarming and in contrast to conventional haemofiltration, which is performed throughout cardiopulmonary bypass. To perform modified haemofiltration, the patient is first weaned off bypass and then the haemofilter pressure is maintained by the difference in pressure between the arterial inflow and the right atrial outflow.
Three studies showed a reduction in inflammatory markers including IL-8 and IL-6 with haemofiltration, although one study found no difference. Two studies showed a reduction in post-operative bleeding, although one study found there to be no difference. Three studies report improved haemodynamics after haemofiltration including improved cardiac index and BP. Five studies report an improved haematocrit or reduced patient weight post haemofiltration. Individual studies also find an increased variability in heparin concentration but no change in aprotinin levels.
All studies are small and therefore there is no reliable data on the effect of haemofiltration on mortality or morbidity.
Three studies showed a reduction in inflammatory markers including IL-8 and IL-6 with haemofiltration, although one study found no difference. Two studies showed a reduction in post-operative bleeding, although one study found there to be no difference. Three studies report improved haemodynamics after haemofiltration including improved cardiac index and BP. Five studies report an improved haematocrit or reduced patient weight post haemofiltration. Individual studies also find an increased variability in heparin concentration but no change in aprotinin levels.
All studies are small and therefore there is no reliable data on the effect of haemofiltration on mortality or morbidity.
Bottom Line:
Haemofiltration will increase the haematocrit, reduce some inflammatory markers and may increase the variability of heparin levels. It may also reduce post-operative blood transfusion and possibly increase BP and cardiac index immediately after haemofiltration, although no differences in morbidity or mortality have ever been shown.
References:
- Despotis GJ, Levine V, Filos KS, et al.. Hemofiltration during cardiopulmonary bypass: the effect on anti-Xa and anti-IIa heparin activity.
- Babka RM, Petress J, Briggs R, et al.. Conventional haemofiltration during routine coronary bypass surgery [erratum appears in Perfusion Nov;12(6):347].
- Tassani P, Richter JA, Eising GP, et al.. Influence of combined zero-balanced and modified ultrafiltration on the systemic inflammatory response during coronary artery bypass grafting.
- Van Norman GA, Patel MA, Chandler W et al.. Effects of hemofiltration on serum aprotinin levels in patients undergoing cardiopulmonary bypass.
- Grunenfelder J, Zund G, Schoeberlein A, et al.. Modified ultrafiltration lowers adhesion molecule and cytokine levels after cardiopulmonary bypass without clinical relevance in adults.
- Boga M, Islamoglu, Badak I, et al.. The effects of modified hemofiltration on inflammatory mediators and cardiac performance in coronary artery bypass grafting.
- Blanchard N, Toque Y, Trojette F, et al.. Hemodynamic and echocardiographic effects of hemofiltration performed during cardiopulmonary bypass.
- Onoe M, Magara T, Yamamoto Y, et al.. Modified ultrafiltration removes serum interleukin-8 in adult cardiac surgery.
- Leyh RG, Bartels C, Joubert-Hubner E, et al.. Influence of modified ultrafiltration on coagulation, fibrinolysis and blood loss in adult cardiac surgery.