K . Kashiwa et al .: J Extra Corpor Technol 2024 , 56 , 108 – 113 109
were associated with the required dosage of UFH to maintain this range of ACT in V-A ECMO during lung transplantation .
These data were retrospectively collected from their medical records .
Materials and methods
The present retrospective study was conducted with the approval of the Ethics Committee of the University of Tokyo Graduate School of Medicine / School of Medicine ( Approved No . 11535 ).
Cases
Among all patients who underwent lung transplantation using V-A ECMO from January 2021 to May 2022 , 27 patients who were weaned from V-A ECMO during surgery were included in this study . Of the 27 patients , 7 received single-lung transplantation and 20 received bilateral lung transplantation . In two cases of bilateral lung transplantation , V-A ECMO was initiated after perfusion of the first lung . In the other cases , V-A ECMO was started before implantation of the first lung .
ECMO management
A MERA centrifugal pump ( Senko Medical Industry Co ., Ltd .) and HPO-23WH-C oxygenator ( Senko Medical Industry Co ., Ltd .) were incorporated into the ECMO circuit . The ECMO circuit was primed with approximately 500 ml of lactated Ringer ’ s solution containing 1 unit / ml of unfractionated heparin ( UFH ). 2000 units of UFH were administered at the time of cannulation for the initial dose , and the UFH infusion was started at the rate of 7 – 8 units / kg / h after initiating ECMO . An ACT was measured once every 30 – 60 min , and the infusion rate was adjusted with a target of 160 – 200 s . If ACT was below 150 or 160 s , the UFH infusion rate was increased by 1 or 2 unit / kg / hr , respectively . Otherwise , the UFH infusion rate was not changed . Other parameters were not taken into consideration to adjust the infusion rate of UFH . A Hemocron Jr . Signature + , ACT-LR ( ITC ) was used for ACT measurement . The flow rate of V-A ECMO was based on 2.4 L / min / m 2 and maintained parameters such as arterial pressure , pulmonary artery pressure , and blood gas data within normal limits . Blood gases were measured once every 30 – 60 min , and white blood cell ( WBC ) and platelet counts were measured via Celltac ( Nihon Kohden Kogyo Co ., Ltd .) at the same time points . Body temperature was maintained within normal range in all the cases .
Examination methods
The enrolled patients were divided into two groups based on whether the infusion rate of UFH was increased from the initial infusion rate ( increased group ) or the infusion rate was maintained or decreased ( non-increased group ). Patients ’ data were evaluated at the following time points : before starting ECMO , immediately after starting ECMO , 1 – 2 h after starting ECMO , after reperfusion of one lung , and after reperfusion of the second lung in the case of bilateral lung transplantation .
Statistical analysis
Values are shown as mean ± standard deviation or median ( interquartile range ) depending on data distribution . Student ’ s t-test and Wilcoxon ’ s rank sum test were used for comparison between the two groups , and p < 0.05 was considered significant . Fisher ’ s exact test was performed for categorical data . Receiver operating characteristic ( ROC ) analysis was performed to evaluate the performance of discrimination . The cutoff value was determined by the Youden index . Data were analyzed using JMP Pro17 ( SAS Institute , Cary , NC , USA ).
Results
Patients ’ characteristics and V-A ECMO performance
Of the 27 patients 10 were categorized into the increased group , and 17 into the non-increased group . None of the patients in the increased group needed to have a reduction in their UFH infusion rate . Correspondingly none of the patients in the nonincreased group required to increase the UFH infusion rate . Two patients in whom V-A ECMO was introduced after reperfusion of the first lung were classified into the non-increase group because the UFH infusion rate after starting ECMO was not increased . As shown in Table 1 , no statistically significant difference was observed between the two groups in height , weight , body surface area , preoperative hematocrit , platelet count , fibrinogen concentration , WBC count , C-reaction protein ( CRP ), albumin and activated partial thromboplastin time ( APTT ), preoperative use of immunosuppressants . Bilateral lung transplantation was performed in 90.0 % of the increased group and 64.7 % in the non-increased group . The duration of ECMO was significantly longer in the increased group compared with the non-increased group ( 314.2 ± 48.4 versus 257.9 ± 70.5 min , p = 0.035 ). The lung diseases in each group are shown in Table 2 . There was no evident difference in the distribution of lung diseases between the groups .
Changes in ACT value , platelet count , WBC count , and infusion rate of UFH during V-A ECMO
Because the UFH infusion rate was adjusted based on ACT in each patient , the ACT values were lower and the infusion rates of UFH were higher in the increased group during the surgery ( Table 3 ). UFH infusion rate was increased after 161.3 ± 72.7 min from starting ECMO in the increased group ( Table 1 ). The timing of the UFH infusion rate increases was approximately 100 min before the end of ECMO in the nonincreased group . No significant difference in platelet count was observed between the two groups at any time points ( Table 4 ). However , at 1 – 2 h after starting ECMO , the WBC counts were significantly higher in the increased group compared with the non-increase group ( p = 0.046 ). Although there was no statistically significant difference in the WBC count at