32 J . Blanco-Morillo et al .: J Extra Corpor Technol 2023 , 55 , 30 – 38
Figure 2 . Diagram of sample composition . HAR group was recruited from 01 / 2014 to 12 / 2016 , while CG was recruited from 01 / 2012 to 12 / 2013 . Abbreviations : CG – control group ; Hgb – Haemoglobin ; CPB – cardiopulmonary bypass ; ECMO – extracorporeal membrane oxygenation .
HG patients received the standardized HAR circuit ( 760 mL ) ( Figure 3 ), being initially primed with 1000 mL of Isofundin Ò ( B . Braun , Melsungen , Germany ). Then , the HAR procedure was applied by following a simple six-step procedure which does not increase the operative time . After recirculation , the circuit was clamped and offered to the surgeon . Then , lines were cut and the crystalloid in the venous line was drained to the hard-shell reservoir . All exceeding volume was diverted through the recirculation line of the oxygenator to a collector bag during the arterial cannulation . When the arterial line was connected priming was also discarded . Afterwards , 400 mL of autologous blood was retrogradely “ sequestered ” from the aorta during venous cannulation , to permit the succeeding antegrade repriming of the pump head and oxygenator . In order to avoid hypotension ( MAP < 60 mmHg ), backflow during sequestration did not exceed �250 mL / min and the anaesthesiologist considered the administration of phenylephrine boluses ( 0,01 mg ) in some cases . Thereby , the haemodilutional impact of CPB initiation for treated patients represented 300 mL ( Figure 4 ).
All recruited patients were induced into general anesthesia with Propofol , Rocuronium , and Remifentanil in boluses . Hypnosis was maintained with sevoflurane according to monitoring , to avoid a bispectral index < 60 ( BIS , Medtronic , Minneapolis , USA ). Ten mg / kg of tranexamic acid was administered during the induction , and a continuous infusion of 1 mg / kg / h was maintained during CPB . A 300 UI / kg bolus of sodium heparin was used as an initial dose to achieve anticoagulation . Target-activated clotting time ( ACT ) during CPB was > 440 s ( Hemochron Signature Elite , Werfen , Spain ), Heparin was reversed with protamine 1:1 after CPB . Afterward , the additional procoagulant strategy was thromboelastometric-guided ( ROTEM Delta , Werfen , Spain ) in every case to reduce postoperative coagulopathy .
Hgb drop below 8 mg / dL was strictly avoided . Therefore , the Renaflo II HF2000 hemofilter ( Cantel Medical Corp , Little Falls , NJ , USA ) was applied for continuous ultrafiltration ( CUF ) to compensate for hemodilution , when possible . Otherwise , if the circulating volume was not sufficient , red-bloodcells ( RBC ) transfusion was initiated [ 14 ].
During CPB , pump index and mean arterial pressure was maintained within ranges of 2 – 2.4 L / min / m 2 and 50 – 80 mmHg , respectively . Cardioplegia was partially haematic ( 4:1 ), cold , intermittent , and predominantly antegrade for both groups and did not exceed 1000 mL of the crystalloid fraction . The temperature was actively maintained over 35 ° C to avoid hypothermia [ 15 , 16 ]. Following an alpha-stat strategy , euglycemia , osmolarity , and acid-base balance were also preserved in a physiologic range . After cross-clamp release , 3 mg of magnesium