176 K . Kohlsaat et al .: J Extra Corpor Technol 2023 , 55 , 175 – 184
of the CPB circuit [ 14 – 19 ]. When a blood prime is indicated , this technique is used prior to CPB initiation in order to create more physiologic electrolytes , glucose , and lactate values [ 15 ]. The PBUF process importantly creates a way to have more standardized prime values when using banked blood .
The use of PBUF has been shown to attenuate cardiac impairment seen during the early reperfusion periods and to reduce pulmonary dysfunction in neonates [ 13 ]. Delaney et al . reported on the impact PBUF had on potassium concentration [ 15 ]. To reduce the risk of transfusion-related hyperkalemic cardiac arrests in small children , they measured analytes at four designated time points . They found that the age of the red blood cell ( RBC ) unit was linearly associated with increased potassium concentration , but that the mean potassium concentration decreased from 10.9 to 6.0 mEq / L ( p = 0.001 ) utilizing their technique of PBUF processing [ 15 ].
The use of PBUF can also slow down the activation of the coagulation pathway and attenuate the inflammatory response [ 15 , 16 , 20 ]. Nagashima et al . saw significantly reduced concentrations of bradykinin and high molecular weight kininogen following the use of PBUF in neonates undergoing an arterial switch operation , highlighting a possible advantage of PBUF in patients who require a blood prime for CPB [ 16 ].
The American Society of Extracorporeal Technology ( AmSECT ) is the primary national organization for perfusionists . AmSECT published Standards and Guidelines for Pediatric and Congenital Perfusion Practice in 2019 [ 21 ]. Standard 13.2 states that the perfusionist shall correct any physiologic abnormalities in blood-primed circuits . Additionally , guideline 13.1 recommends prebypass ultrafiltration as one method to achieve the standard . The process of blood priming the CPB circuit is not standardized across institutions and there are several methods used to correct for abnormal prime values [ 18 ]. We hypothesized that our method of PBUF would normalize and standardize blood primes with more consistent values prior to initiation of CPB without adversely affecting clinical outcomes .
Objectives
We aimed to determine the effects of the addition of PBUF to CPB circuits requiring a blood prime for neonates and infants . Our institution had a long-standing standardized method of blood priming . Some perfusionists elected to PBUF all of their circuits after a standard blood prime , while others did not out of concern for unknown effects . A multidisciplinary meeting of perfusionists , surgeons , anesthesiologists , and nurses determined that the primary concern centered on the use of 0.45 % saline in the process , which could potentially lyse RBCs and increase plasma-free hemoglobin . Lowering the prime sodium level closer to its physiologic range also had the potential to increase edema after CPB . Additionally , there were concerns that changing practice may lead to an increase in adverse events and have a negative impact on patient outcomes . Our institutional practices allowed for a natural trial in that some perfusionists utilized PBUF while others maintained the standard priming technique due to the above concerns .
Materials and methods
This retrospective cohort study included all consecutive infants at our institution under one year of age undergoing cardiac surgery with CPB between August 2017 and September 2021 . The index procedure of each hospitalization was included . The study was exempted by the Institutional Review Board (# IRB-P00038496 ) with a waiver of consent . The primary aim of the study was to determine how effective PBUF was at normalizing blood prime electrolyte , glucose , and lactate values prior to the initiation of bypass . The secondary aim was to determine if PBUF was associated with any adverse intraoperative or postoperative outcomes . Outcomes , primary predictors , and covariates
The primary outcome was the difference in sodium , potassium , glucose , and lactate levels between the standard prime ( SP ) cohort and the PBUF cohort during the intraoperative period . The time points of interest included ( a ) first prime values ( standard prime in both groups ), ( b ) final prime values ( different only in the PBUF cohort ), ( c ) first values measured after bypass initiation , and ( d ) last values measured prior to CPB cessation . We also looked at differences in osmolality between the two cohorts , particularly at time point ( b ). Secondary outcomes included differences in clinical outcomes between the PBUF and SP cohorts . The clinical outcomes measured included postoperative ventilation duration , cardiac intensive care unit ( CICU ) length of stay ( LOS ), postoperative hospital LOS , and major adverse events ( unplanned reoperation , re-exploration for bleeding , mediastinitis , central nervous system ( CNS ) complications , extracorporeal membrane oxygenation ( ECMO ), pacemaker , and mortality ). We also examined phenylephrine use on bypass , total ultrafiltration volume , and inotrope requirements .
The primary predictor was the use of PBUF . Other preoperative covariates included age ; sex ; case complexity as measured by the Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery ( STAT ) mortality categories ; prematurity ; noncardiac anomalies / chromosomal abnormalities / syndromes ; and preoperative risk factors as defined in the STS Congenital Heart Surgery Database data collection form ( mechanical ventilation , ECMO , renal dysfunction , cardiopulmonary resuscitation , stroke , sepsis , seizures , hepatic dysfunction , necrotizing enterocolitis ). We also collected information on whether the patient had prior cardiac surgery , whether the index operation was a palliative surgery versus a complete repair resulting in biventricular circulation , as well as the urgency status of the surgery categorized as elective , urgent , emergent , or salvage .
Intraoperative covariates included total CPB time , aortic cross-clamp time , circulatory arrest time , and adequacy of repair as measured by intraoperative and postoperative Technical Performance Score ( TPS ) [ 22 ]. Cardiopulmonary bypass circuit priming
All CPB cases utilized a circuit consisting of a CAPIOX FX-05 oxygenator ( Terumo Cardiovascular , Inc ., Ann Arbor ,