ostra niewydolno nerek jest rzadkim ( 215% ) , ale bardzo niebezpiecznym powikaniem operacji kardiochirurgicznych , obarczonym miertelnoci rzdu 4080% . celem pracy bya ocena wpywu okrelonych czynnikw na miertelno wrd pacjentw kardiochirurgicznych poddanych terapii nerkozastpczej z powodu ostrej pooperacyjnej niewydolnoci nerek . retrospektywnej analizie poddano dane 45 pacjentw operowanych kardiochirurgicznie w latach 20092013 , u ktrych wczono terapi nerkozastpcz z powodu pooperacyjnej ostrej niewydolnoci nerek . analizowano zwizek czynnikw okoooperacyjnych ze miertelnoci , dzielc przy tym pacjentw na grup nr 1  zmarych w trakcie leczenia ; oraz grup nr 2  tych , ktrzy przeyli do momentu wypisania ze szpitala . przed wypisem ze szpitala zmary 23 osoby ( 51,11% ) ( grupa nr 1 ) . i wyszy redni wynik w skali euroscore ( 9,28 vs 7,15 ) ( p < 0,05 ) , czciej przechodzili zabieg zoony ( 63,63% vs 28,57% ) ( p < 0,05 ) , czciej wymagali podawania katecholamin w okresie pooperacyjnym ( 100% vs 68,42% ) ( p < 0,005 ) oraz mieli wiksze rednie stenie mocznika we krwi przed rozpoczciem dializ ( 156,65 vs 102,54 mg / dl ) ( p wysoki wynik w skali euroscore , zabieg zoony , due stenie mocznika we krwi przy wczaniu terapii nerkozastpczej oraz potrzeba uycia katecholamin w okresie pooperacyjnym okazay si statystycznie istotnymi czynnikami zwikszajcymi miertelno w badanej populacji chorych . wymienione czynniki mog posuy do identyfikacji pacjentw o zwikszonym ryzyku zgonu , wymaga to jednak potwierdzenia w dalszych badaniach na szerszej populacji chorych . acute renal failure ( arf ) requiring the use of renal replacement therapy ( rrt ) is a rare , but very severe complication of cardiac surgery . it is a sudden renal insufficiency accompanied by higher creatinine blood level and oliguria , defined as urine output < 0.5 ml / kg per hour . its incidence varies from 2% to 15% with overall mortality as high as 40% to 80% , highlighting the importance of this issue [ 1 , 2 ] . moreover , arf has been proven to be an independent predictor of death after cardiac surgery . one of the main problems faced by physicians in everyday practice is a lack of consensus on the diagnostic criteria for arf and the optimal time to initiate rrt . in this study arf was considered in the case of oliguria or if there was a clinical need for rrt initiation ( e.g. uncontrollable hyperkalaemia ) . the aim of our study was to find differences between two observed groups of patients , who underwent dialysis as a treatment for arf after cardiac surgery : those who died during treatment ( group 1 ) and those who survived until hospital discharge ( group 2 ) . modifiable and unmodifiable factors connected with heart operation were analysed in order to find predictors of mortality in the examined population . the retrospective analysis included 45 patients diagnosed with arf after cardiac surgery and subsequently treated with rrt in our clinic in years 2009 to 2013 . data was obtained from patients records as well as the hospital 's cardiac surgery database . collected information was divided into three categories : preoperative factors : patient 's sex , age , weight , height , body mass index ( bmi ) , ejection fraction ( ef ) , euroscore value , creatinine blood level , estimated glomerular filtration rate ( egfr ) on admission , recent myocardial infarction (  90 days before surgery ) or angiography procedure (  14 days before surgery ) , history of diabetes , hypertension , and heart failure.factors associated with the surgery : procedure other than coronary artery bypass graft surgery ( cabg ) , reoperation , concomitant surgery ( e.g. cabg plus aortic valve replacement ) , use of extracorporeal circulation ( ecc ) , time of ecc , time of cross clamp , and use of catecholamines and intra - aortic balloon pump ( iabp ) during surgerypostoperative factors : respiratory support ( > 4 days after surgery ) , drainage ( > 1000 ml/24 h ) , day of rrt initiation , creatinine , urea and potassium blood levels at rrt initiation , bacteremia and maximal c - reactive protein ( crp ) level , and administration of catecholamines and iabp in the postoperative period . preoperative factors : patient 's sex , age , weight , height , body mass index ( bmi ) , ejection fraction ( ef ) , euroscore value , creatinine blood level , estimated glomerular filtration rate ( egfr ) on admission , recent myocardial infarction (  90 days before surgery ) or angiography procedure (  14 days before surgery ) , history of diabetes , hypertension , and heart failure . factors associated with the surgery : procedure other than coronary artery bypass graft surgery ( cabg ) , reoperation , concomitant surgery ( e.g. cabg plus aortic valve replacement ) , use of extracorporeal circulation ( ecc ) , time of ecc , time of cross clamp , and use of catecholamines and intra - aortic balloon pump ( iabp ) during surgery postoperative factors : respiratory support ( > 4 days after surgery ) , drainage ( > 1000 ml/24 h ) , day of rrt initiation , creatinine , urea and potassium blood levels at rrt initiation , bacteremia and maximal c - reactive protein ( crp ) level , and administration of catecholamines and iabp in the postoperative period . statistica ( data analysis software system ) version 12.0 , using  test , t - test , and u mann - whitney test . in total 1.25% of patients treated in our clinic in years 2009 - 2013 ( 45 out of 3590 patients ) developed arf requiring rrt after cardiac surgery . as shown in table i , patients who died during treatment ( group 1 ) were older and had higher mean bmi value than those who survived until discharge . before the operation patients in group 1 had lower mean ejection fraction ( ef ) value ; in this group we also observed higher percentage of patients diagnosed with heart failure , hypertension , or recent (  90 days before surgery ) myocardial infarction and higher percentage of angiography procedures (  14 days before surgery ) . after the statistical analysis the only significant preoperative death risk factor proved to be high score on the euroscore scale , with a mean value of 9.28 in group 1 ( survivors ) vs. 7.15 in group 2 ( p < 0.05 ) . mean value in the analysed group of patients percentage of patients in the analysed group bmi body mass index , egfr  estimated glomerular filtration rate , cabg  coronary artery bypass graft , ecc  extracorporeal circulation , or operating room , iabp  intra - aortic balloon pump , rrt  renal replacement therapy , crp c reactive protein when it comes to factors associated with the surgery , only the higher percentage of concomitant cardiac surgeries ( e.g. cabg and concomitant aortic valve replacement ) in group 1 ( 63.63% vs. 28.57% ) turned out to be a statistically significant death predictor ( p < 0.05 ) . patients in group 1 were more often reoperated , had procedure other than cabg , and a higher percentage of surgeries in extracorporeal circulation ( ecc ) . in this group administration of catecholamines and use of iabp during the operation were less frequent in group 1 . ( 100% vs. 68.42% ) ( p < 0.005 ) and higher blood urea values at rrt initiation ( 156.65 mg / dl vs. 102.54 mg / dl ) ( p < 0.05 ) proved to be statistically significant death predictors . a higher percentage of patients in group 1 required administration of catecholamines ( postop . ) , iabp ( postop . ) , respiratory support ( > 4 days ) , and drainage > 1000 ml/24 h. they showed higher incidence of bacteraemia and higher maximal crp levels . surprisingly , in group 1 , rrt was started earlier ( 4.5 vs. 5.47 day ) with lower mean blood levels of urea , creatinine , and potassium prior to its initiation ( table i ) . although there are many studies that have focused on the problem of arf after cardiac surgery , there is still no consensus on a clear definition or precise pathophysiological mechanisms , risk factors , and practical guidelines concerning arf patients , which in turn leads to poor outcomes . it is not connected with disturbance of kidneys themselves , as in the case of renal arf . hypoperfusion of renal medulla , caused by vasoconstriction of renal arterioles and redistribution of blood flow within kidneys , seems to be the most likely mechanism leading to postoperative arf . therefore , if rapid and effective treatment reinforcing renal blood flow is undertaken the filtration will increase as well as the urine output . that is why fast diagnosis and treatment is of utmost importance to avoid arf [ 46 ] . nowadays , patients with acute kidney injury are often ordinated with rrt only after significant disturbance of acid - alkaline balance . the tendency is to delay the process of dialysis as long as the imbalance does not occur in order to avoid side effects of rrt . there is a high number of risk factors mentioned in literature , suggested to provoke arf after heart surgery , including : age , diabetes [ 912 ] , previous cardiovascular surgery , cpb time , duration of cross - clamp time , generalised inflammatory response as a consequence of the cpb circuit , and exposure to iodine dye ( coronarography ) a short time before surgery . however , analysis of those variables did not change any statistically important differences between group 1 and 2 . on the other hand , euroscore or the need of vasopressor support after surgery   proved to be statistically meaningful mortality predictors in the group of patients treated with rrt . however , those factors are generally associated with higher death risk in all patients undergoing surgery , not peculiarly those diagnosed with arf . surprisingly , there was a relevant difference in urea level at rrt initiation without a significant discrepancy in creatinine level . therefore , level of urea should not be underestimated or omitted when creatinine level is within normal limits . also , the fact of undergoing a concomitant surgery turned out to be a statistically important factor affecting the patients mortality rate . however , parameters such as cpb use , cpb time , or cross clamp time did not prove to be of statistical significance . a relatively small group of patients and lack of follow - up observation after discharge ( only short - term results ) may have been limitations of our study . statistically significant death predictors in the group of patients treated with rrt because of acute kidney insufficiency that occurred after cardiac surgery turned out to be : high euroscore , concomitant surgery , high urea level at rrt initiation , and admission of catecholamines in the postoperative period . the presented observations should be further investigated on a larger group of patients , followed by the creation of practical guidelines on the treatment of postoperative arf and the place of renal replacement therapy within that process .
introductionacute renal failure ( arf ) is a rare ( 2 - 15% ) , but severe complication of cardiac surgery with overall mortality reaching 40 - 80% . in order to save patients lives 
 they are treated with renal replacement therapy ( rrt ) . 
 the aim of our study was to assess the impact of different perioperative factors on mortality among patients treated with rrt because of acute renal failure , which occurred as a complication of a heart surgery.material and methodsretrospective analysis included 45 patients , operated in the years 2009 - 2013 , who underwent renal replacement therapy in order to treat postoperative arf . 
 the perioperative factors were analysed in two groups : group 1  patients who died before discharge ; and group 2  those who survived until hospital discharge.resultsforty-five of 3509 cardiac surgical patients ( 1.25% ) required rrt after the surgery . 
 a total of 23 ( 51.11% ) died before discharge ( group 1 ) . 
 patients in group 1 were characterised by older age ( 70.21 vs. 67 years ) , higher mean euroscore value ( 9.28 vs. 7.15 ) ( p < 0.05 ) , higher percentage of concomitant surgery ( 63.63% vs. 28.57% ) ( p < 0.05 ) and of admission of catecholamines in the postoperative period ( 100% vs. 68.42% ) ( p < 0.005 ) , and higher mean urea blood level prior to rrt initiation ( 156.65 vs. 102.54 
 mg / dl ) ( p < 0.05).conclusionsthe statistically relevant death predictors proved to be : high euroscore , concomitant surgery , and high urea level at rrt initiation and admission of catecholamines in the postoperative period . 
 after conformation in further studies , those factors may prove useful in stratification of death risk among surgical patients requiring rrt .