**5.2 Ischemic complications**

It occurs in about 5–6% of children and adults [8, 36], and is best identified on MR imaging. Due to multifactorial etiology for ischemic strokes such as hypotension, large vessel occlusion, thromboembolism, septic embolism, etc. it is difficult to characterize lesions anatomically or to prognosticate based on imaging. Timing of injury is also difficult to ascertain. There are conflicting reports on laterality of lesions [37] but seem to occur in the middle cerebral artery vascular territory. A single center pediatric study found that majority of strokes were bilateral, a few were unilateral right sided lesions and no patients had unilateral left sided strokes; majority of the lesions were in the anterior cerebral circulation distribution [22]. Ischemic lesions are associated with electrographic seizures and decreased survival [38]. Asymmetry in regional cerebral saturation or on continuous EEG monitoring might be suggestive of focal ischemia. Once detected, hemodynamics should be optimized through adequate pump flows on VA ECMO, vasoactives can be used if needed, and further neurologic injury should be minimized by avoiding hyperoxia and treating seizures.

#### **5.3 Seizures**

Although less common than intracranial hemorrhage and stroke, seizures can be difficult to recognize if they are nonconvulsive or subclinical. A study of children and neonates undergoing ECMO revealed that 18% of patients had electrographic seizures, with 61% of those patients having electrographic status epilepticus and 83% having exclusively electrographic seizures [39]. Another recent study of neonatal and pediatric patients found electrographic seizures in 23% of their patients, especially within the first 24 hours of ECMO [40]. Patients with seizures had decreased survival to discharge (44% versus 74%). Older studies that reported lower incidence of seizures may have missed patients if only clinical seizures were reported, as the routine use of continuous EEG monitoring for patients is not yet a widespread practice, although recent recommendations advocate for its use in ECMO. Given that patients on ECMO are a high risk population, seizures should be treated with the help of neurologists.

### **5.4 Sensorineural hearing loss**

Sensorineural hearing loss has been reported in neonatal ECMO graduates with a frequency of 3–21% [41]. Diagnosis of congenital diaphragmatic hernia, duration of ECMO, and aminoglycoside antibiotic use were associated with hearing loss [42]. A follow-up study found that even children diagnosed with hearing loss after ECMO can go on to have normal language development [43].

### **5.5 Myopathy**

Prolonged immobilization, sedation and paralytics, hemodynamic instability, all contribute to neuromuscular weakness in ECMO patients. Studies have proved that active physiotherapy, with early mobilization, is feasible and safe in ECMO patients when performed with an experienced, multidisciplinary team [44, 45]. It may also shorten hospital duration and improve functional outcomes for patients [46].

**207**

*5.7.2 Apnea testing on ECMO*

*Neurologic Complications and Neuromonitoring on ECMO*

A small study of pediatric cardiac ECMO patients diagnosed delirium in all their patients, in 21% of coma-free ECMO days [47]. Use of validated delirium screening tools can aid in early recognition and management of delirium. The move to liberate ICU patients should include patients on ECMO whenever feasible, with an emphasis

Progressive cerebral edema and large hemorrhages, whether from insults prior to cannulation or secondary to complications from ECMO, can ultimately lead to brain death in patients supported on ECMO. Diagnosis of brain death can be challenging on ECMO, but is important to determine as it is medically and ethically unreasonable to continue ECMO for a patient who has met criteria for brain death.

The American Academy of Neurology issued guidelines on the determination of brain death in adults, most recently revised in 2010 [48]. Similarly the Society of Critical care Medicine, American Academy of pediatrics and the Child Neurology Society jointly published guidelines for the determination of brain death in children and infants in 2011 [49]. The following general criteria apply to all patients undergoing brain death testing, although the specifics may vary by institutional policies. Patients should be relatively normothermic, and electrolytes and glucose should be within acceptable ranges. Any medications that may interfere with respiratory drive and neurologic function must be discontinued, with drug levels obtained if needed. The patient must demonstrate absence of all motor function and lack of responsiveness to stimuli, except spinal reflexes. Cranial nerve testing should reveal absence of pupillary reflexes, corneal reflexes, oculovestibular and oculocephalic reflexes,

The apnea test is an important component of brain death testing without which ancillary studies such as cerebral angiography, nuclear scanning for cerebral blood flow, electroencephalography, transcranial Doppler etc. are required to demonstrate absence of blood flow to the brain. The apnea test is performed to demonstrate absence of spontaneous respiratory drive in the presence of rising paCO2 levels in the blood. The patient is pre-oxygenated with 100% FiO2 and ventilated to achieve normocarbia, if possible. A baseline blood gas analysis is obtained. The patient is then disconnected from the ventilator and oxygenated via a T-piece or flow-inflating anesthesia bag. The patient is closely observed for signs of spontaneous respiration or chest rise. Serial blood gases are obtained at every few minute intervals. A rise in paCO2 > 60 mmHg and > 20 mmHg above baseline is conclusive of absence of respiratory drive. If the patient were to become hypoxic or hemodynamically unstable the apnea test should be discontinued and ancillary studies obtained.

While clinical criteria of absence of cortical function and brain stem reflexes can be assessed in the usual manner, apnea testing can be difficult on ECMO. A proposed method for apnea testing is oxygenating the patient by use of continuous positive airway pressure (CPAP) or T-piece or by placing the patient on a selfinflating anesthesia bag with a PEEP valve, while watching for spontaneous respirations. The oxygenator on the circuit can then be capped. Alternatively, the sweep

absence of cough and gag reflexes and absent brain stem reflexes.

*DOI: http://dx.doi.org/10.5772/intechopen.85103*

**5.6 Delirium**

on delirium prevention.

**5.7 Brain death on ECMO**

*5.7.1 Determination of brain death*
