In this study, we evaluated the efficacy of ECPR for patients with PEA in a hybrid ER setup. Twelve patients with PEA were transferred as ECPR candidates and were assessed as to whether they were indicated for ECPR based on our hybrid ER strategy. Nine patients did not undergo unnecessary ECMO induction, and two of three patients who underwent ECPR had favourable neurological outcomes. At present, 14 centres in Japan have a hybrid ER, but only our centre has introduced this strategy as far as we know.
Several studies have reported successful resuscitation using ECPR induction for patients with PEA [4,5,6, 19]. Diek et al. reported that the survival rate of patients with PEA for ECPR was 23.8% [20]. Because shockable rhythms are a good candidate for ECPR [2, 3], non-shockable rhythms may also be a candidate for ECPR [21]. Patients with PEA with witnesses were more likely to have a fatal pulmonary embolism [7], and favourable outcomes were expected by inducing ECMO [8, 9]. Therefore, it seems that CA due to pulmonary embolism is expected to also have a favourable neurological outcome by ECPR induction. Furthermore, some reports demonstrated the use of ECPR in cases of accidental hypothermia with PEA [22, 23]. The disease can be diagnosed based on medical history and physical findings, and aggressive ECMO induction may result in improved neurological outcomes.
Those with poor neurological outcomes after ECPR due to aortic disease and intracranial haemorrhage were not indicated for ECPR [13]. Although ECPR for intracranial haemorrhage has not been reported, CA caused by this condition has been reported to have unfavourable neurological outcomes [14, 15]. These patients could not be considered for ECPR. Therefore, whether ECPR is indicated before ECMO induction should be determined. However, in our study, one patient with AAD without cardiac tamponade and rupture had a favourable neurological outcome (Case 6). Regardless of CA caused by AAD, patients without cardiac tamponade and rupture, for instance, coronary artery malperfusion, may be a candidate for ECPR.
In conventional ECPR performed in the ER or angiography room, these diseases cannot be diagnosed before ECMO induction. A hybrid ER enables a diagnosis to be made on the basis of a CT scan before ECMO induction and simultaneous ECMO induction without relocating the patient. Furthermore, the use of fluoroscopy may be beneficial in terms of avoiding incorrect cannula placement and bleeding complications [18]. Therefore, our protocol is more useful than conventional ECPR. In our study, all patients with diseases not indicated for ECPR were excluded because of the initial CT scan and to avoid unnecessary ECMO induction in hybrid ER. Therefore, our strategy would contribute to the cost-effectiveness of ECPR.
Of the three patients who underwent ECPR, one patient (Case 3) died because of ACS. In this case, it was extremely difficult to detect coronary artery disease as a cause of CA on the initial CT scan before ECMO induction because there were no findings of coronary artery disease such as severe calcification of the coronary artery. The aim of our study was to exclude non-indication of ECPR for patients such as intracranial haemorrhage and aortic diseases. Therefore, we believe that this case was a limitation of this strategy.
Among all the patients in this study, nine patients had a medical history and five of these had a history of cardiac disease. However, because the number of cases is extremely small, it could not be analysed statistically. In situations of ECPR needed, we are often required to make a decision with limited information about medical history.
There are several limitations to this study. First, it was a retrospective, single-centre study. Second, the number of patients may have been small with no other control groups and the investigation was based on a case series targeting a relatively limited number of patients. Third, the responsibility of decision-making regarding the treatment to be conducted was that of the physician.