The Journal of ExtraCorporeal Technology Issue 55-4 | Page 32

182 K . Kohlsaat et al .: J Extra Corpor Technol 2023 , 55 , 175 – 184

Table 7 . Additional operative and ICU characteristics .

Values shown are number ( percent ) or median [ 25th , 75th percentiles ]. hr : hours ; ICU : intensive care unit ; kg : kilograms ; mcg : microgram ; mg : milligrams ; min : minutes ; mu : milliunits ; PBUF : pre-bypass ultrafiltration .

along with the requisite calcium gluconate and sodium bicarbonate added to the blood prime . Secondly , humoral factors such as cytokines , interleukins , and other cell signaling molecules are removed . It is worth noting that the 0.45 % saline was not given to the patient during PBUF . Instead , it was administered to the blood prime to help account for the effects that the requisite sodium bicarbonate administration would have on prime sodium values .

Nagashima et al . applied the technique of PBUF to the blood prime pre-CPB for infants specifically undergoing an arterial switch operation [ 16 ]. In a preliminary study , they found that even when using outdated donated blood , which has far less physiologic values than anything that would normally be given to a patient , the electrolyte and acid-base balance can be dramatically improved in a time period as short as 30 minutes [ 16 ]. Specifically in this population , they saw that PBUF reduced cardiac impairment at early reperfusion periods and reduced pulmonary dysfunction . To note , our method of PBUF required approximately 15 minutes to perform .

Limitations

It is important to note that our study was a retrospective review , which generally comes with limitations . One limitation of our study was that PBUF was performed only on the portion of the reconstituted blood unit that was included in the circuit prime . This equated to roughly half of the unit ( approximately 200 mL of a 400 – 450 mL unit ) being treated . This limitation may help explain why the primary outcome results were similar for the last values on bypass . Our updated protocol implemented after this study includes PBUF of the entire unit of reconstituted whole blood .

The updated protocol starts with a 3 IU / mL heparinized Plasma-Lyte prime for the 285 – 300 mL circuit to which the remainder ( after a non-heparinized portion is given to the anesthesia team for PRN pre-bypass transfusion ) of the 3 IU / mL heparinized reconstituted whole blood unit is then added . The 100 % oxygen sweep gas is set to 0.4 LPM with 0.02 LPM CO 2 . The circuit volume is hemoconcentrated down to 250 mL and then 250 mL of additional Plasma-Lyte is added keeping the reservoir volume below the anti-foam coating level ( 500 mL in the Terumo CAPIOX FX 05 reservoir ). The reservoir volume is then hemoconcentrated down to 150 mL and the hemoconcentrator effluent line is clamped . Sodium bicarbonate ( 17 [± 1 ] mEq ) is added for pH adjustment . Heparin ( 800 units ) is added to help account for any losses in the effluent . Calcium gluconate ( 600 [± 100 ] mg ) is added for a target ionized calcium level of 0.8 – 1.2 mmol / L . Then , 100 mL of 0.45 % saline is added . The additives are recirculated and then flow through the PBUF circuit is stopped . Approximately 175 mL of circuit volume is then sent back to the original blood unit bag for later transfusion while on bypass . A blood gas verifies that the prime values are within the target range . To note , this protocol results in a circuit prime hematocrit of approximately 20 %. We have found that this commonly results in a dilutional hematocrit of approximately 30 % once on bypass . Of course , the circuit prime volume can be further hemoconcentrated if a higher prime and / or dilutional hematocrit is desired .