178 K . Kohlsaat et al .: J Extra Corpor Technol 2023 , 55 , 175 – 184
 Table 1 . Patient characteristics / demographics .
|  |  Standard prime ( n = 417 ) |  PBUF ( n = 704 ) |  P-value | 
|  Age at surgery ( months ) |  3 [ 25d , 6 ] |  3 [ 8d , 6 ] |  0.086 | 
|  Age at surgery 30 days |  109 ( 26 %) |  216 ( 31 %) |  0.12 | 
|  Sex female |  195 ( 47 %) |  328 ( 47 %) |  1.0 | 
|  Premature 1 |  98 ( 24 %) |  139 ( 20 %) |  0.15 | 
|  Palliative procedure |  82 ( 20 %) |  156 ( 22 %) |  0.36 | 
|  1 prior surgery with CPB |  67 ( 16 %) |  98 ( 14 %) |  0.34 | 
|  1 prior surgery without CPB |  30 ( 7 %) |  51 ( 7 %) |  1.0 | 
|  Noncardiac anomaly |  115 ( 28 %) |  206 ( 29 %) |  0.58 | 
|  Chromosomal abnormality |  127 ( 30 %) |  221 ( 31 %) |  0.79 | 
|  Syndrome |  138 ( 33 %) |  221 ( 31 %) |  0.60 | 
|  Preoperative risk factor 2 |  163 ( 39 %) |  308 ( 44 %) |  0.13 | 
|  STAT mortality category 1 |  50 ( 12 %) |  100 ( 14 %) |  0.045 | 
|  2 |  76 ( 18 %) |  108 ( 15 %) |  | 
|  3 |  85 ( 20 %) |  170 ( 24 %) |  | 
|  4 |  172 ( 41 %) |  249 ( 35 %) |  | 
|  5 |  28 ( 7 %) |  72 ( 10 %) |  | 
|  Not assigned |  6 ( 1 %) |  5 ( 1 %) |  | 
|  Urgency status ( n = 413 , 702 ) Elective |  212 ( 51 %) |  319 ( 45 %) |  0.075 | 
|  Urgent |  195 ( 47 %) |  377 ( 54 %) |  | 
|  Emergency |  6 ( 1 %) |  5 ( 1 %) |  | 
|  Salvage |  0 ( 0 %) |  1 (< 1 %) |  | 
|  Cardiopulmonary bypass time ( min ) ( n = 417 , 703 ) |  141 [ 103 , 197 ] |  145 [ 104 , 198 ] |  0.50 | 
|  Cross-clamp time ( min ) ( n = 410 , 688 ) |  91 [ 54 , 128 ] |  93 [ 60 , 125 ] |  0.66 | 
|  Any circulatory arrest time ( n = 410 , 692 ) |  75 ( 18 %) |  128 ( 19 %) |  1.0 | 
|  Operating room time ( min ) |  407 [ 338 , 492 ] |  416 [ 341 , 499 ] |  0.69 | 
|  Intraoperative TPS 3 1 |  279 ( 67 %) |  491 ( 70 %) |  0.55 | 
|  2 |  122 ( 29 %) |  190 ( 27 %) |  | 
|  3 |  5 ( 1 %) |  11 ( 2 %) |  | 
|  4 not assigned |  11 ( 3 %) |  12 ( 2 %) |  | 
|  TPS at discharge 4 1 |  204 ( 49 %) |  367 ( 52 %) |  0.44 | 
|  2 |  118 ( 28 %) |  204 ( 29 %) |  | 
|  3 |  79 ( 19 %) |  113 ( 16 %) |  | 
|  4 Not assigned |  16 ( 4 %) |  20 ( 3 %) |  | 
 Values shown are number ( percent ) or median [ 25th , 75th percentiles ]. 1 Less than 37 gestational weeks . 2 Preoperative risk factors include : mechanical ventilation , ECMO , renal dysfunction , cardiopulmonary resuscitation , stroke , sepsis , seizures ,
 hepatic dysfunction , necrotizing enterocolitis , arrhythmias , colostomy , gastrostomy tube , acidosis , hypothyroidism , bronchopulmonary dysplasia , hypo / hyper coagulable , pulmonary hypertension , adrenal insufficiency , tracheostomy , enterostomy , familial history of ischemic heart disease , endocarditis , asthma , implanted defibrillator , pacemaker , bronchiolitis , single lung , diabetes mellitus type 1 . 3 TPS is classified as Class 1 : no residua ; Class 2 : minor residua ; Class 3 : major residua . 4 TPS is classified as Class 1 : no residua ; Class 2 : minor residua ; Class 3 : major residua or reintervention for residua prior to discharge .
 CPB : cardiopulmonary bypass ; Min : minutes ; PBUF : pre-bypass ultrafiltration ; STAT : Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery ; TPS : technical performance score .
 of cell lysis and electrolyte composition based on duration and quality of storage . The use of PBUF provides more physiologic values for measured parameters and does so consistently . The method of PBUF used in this study intentionally did not normalize all values , especially the sodium and glucose , since some clinicians were concerned about an increased risk of edema after CPB given that the osmolality , primarily determined by sodium and glucose , decreased relative to the standard blood prime technique . Therefore , our technique of PBUF produced statistically significant improvements in measured values but not truly physiologic values ( although glucose approached clinical significance ), and this was by design . The last values on CPB were statistically similar , with the exception of glucose , and importantly there were no clinically significant differences . While the use of PBUF provided more physiologic prime values for glucose , sodium , potassium , and lactate that were statistically significant when compared to a standard prime , these advantages did not persist throughout the entire duration of the operation . The time spent on bypass was similar between groups and the median bypass time , which was over two hours , was likely sufficient for the patient ’ s compensatory mechanisms to correct most outlier values . Further ,