**5. Types of neurological complications and their management**

There is a wide variety of neurological injuries that are noted after ECMO including embolic strokes, hypoxic-ischemic encephalopathy, cerebral infarction, intracranial and subarachnoid hemorrhages, seizures, cerebral edema and even brain death. Other complications, such as critical illness myopathy, neuropathies, delirium, hearing loss, vocal cord paralysis etc. are related to prolonged hospitalization and ICU stays, need for prolonged mechanical ventilation or tracheostomy, prolonged exposure to sedation, and limited mobility that often accompany ECMO runs. In this section of the chapter, we will look at some of the more common neurologic complications experienced by patients treated with ECMO.

#### **5.1 Hemorrhagic complications**

Intracranial hemorrhage (ICH) is one of the most common adverse neurologic events on ECMO, carrying a high mortality rate. It can occur as intraparenchymal, intraventricular or subarachnoid hemorrhages. Gestational age at time of ECMO cannulation, severe acidosis needing correction, sepsis, need for epinephrine, therapeutic hypothermia and need for cardiopulmonary resuscitation (CPR) have been associated with intracranial hemorrhage in neonates [29–31]. A longer duration of ECMO, higher activated clotting times (ACTs), presence of bleeding at other sites, pre-admission antithrombotic therapy, and low platelet counts were associated with hemorrhage in adults [32, 33]. Rapid PaCO2 decrease/correction of hypercapnia and renal failure at ICU admission were associated with increased intracranial hemorrhage in one adult study [13]. In order to detect intracranial hemorrhage while on ECMO, cranial ultrasounds are used in neonates while CT imaging is used in children and adults. In one observational study, 42% of the cohort underwent withdrawal of life sustaining therapy, 18% did not require any intervention and 40% were treated. Treatments included hemostatic interventions, ICP management and surgical interventions with 14% of the cohort uneventfully decannulated [34]. Patients that have clinically significant bleeds, with progression of brain injury and little to no improvement on ECMO ultimately end up with withdrawal of life sustaining therapies due to poor prognosis and risk of progression of the bleed. Patients with very small or clinically insignificant hemorrhages can continue their ECMO courses with close neurological monitoring, decannulation at the earliest feasible time and possibly lowering of anticoagulation parameters while balancing thrombotic risks. Platelets and anti-fibrinolytics may need to be administered. Occasionally ECMO circuits can be trialed without any anticoagulation keeping a close eye on the circuit for clots and fibrin deposition. Life-threatening hemorrhage can be severe enough to warrant a craniotomy [7, 35]. Hematoma evacuation on ECMO is high risk and carries a high mortality although there are reports of patients who survived [34]. There is heterogeneity in practice with drugs used for anticoagulation (heparin versus bivalirudin), tests to assess for anticoagulation (TEG,

ROTEM, activated clotting time, PT/PTT, heparin assays) and therapeutic targets for titration. Further research is needed to help develop guidelines and consensus on best practice to minimize and treat bleeding complications on ECMO.
