Comparison of Narcotrend and Cerebral Function Analysing Monitor in Intensive Care to Monitor Seizures and Deep Sedation

The Narcotrend Depth of Anaesthesia Monitor as an Indicator of Seizures and Burst Suppression in the Intensive Care Unit

A study in the use of the Narcotrend depth of anaesthesia monitor to record a) seizures, and b) monitor a level of sedation referred to as 'burst suppression', in sedated patients in the adult and paediatric intensive care.

Studies have shown that patients in coma on the intensive care unit may have subclinical in addition to clinical seizures. Subclinical seizures are seizures that do not show any outward signs and may go undetected.

The current gold standard of recording seizures in the intensive care unit is by non-invasive, continuous monitoring of the electrical activity of the brain by electroencephalography (cEEG) using cerebral function analysing monitor (CFAM).

This is recorded with simultaneous video recording and is performed by Clinical Neurophysiology departments.

There has been a steady increase in demand for this service over recent years. Additionally, CFAM / cEEG is labour intensive and expensive. If trends continue, the proportion of hospitals offering CFAM / cEEG will continue to rise, creating increased demand for specialist staff, of which there are a finite number.

Depth of anaesthesia monitors are used by anaesthetists to assess the level of anaesthesia in sedated patients using specialised, automated EEG analysis and are now recommended by NICE (DG6) to tailor anaesthetic dose to individual patients.

This study aims to investigate the utility of the Narcotrend depth of anaesthesia monitor to monitor for seizures and burst suppression on the adult and paediatric intensive care unit. These monitors are cheaper and more widely available with the scope to be used at every bed space requiring neuro observation on the intensive care unit.

The study aims to recruit all patients who are referred for CFAM / cEEG monitoring at Nottingham University Hospitals (NUH) Trust over a 12 month period. These patients will undergo simultaneous recording using CFAM / cEEG and depth of anaesthesia monitoring.

A non-invasive, prospective, observational, qualitative, comparative study performed on the adult and paediatric intensive care unit of NUH Trust. Study population will be all adult and paediatric patients referred for CFAM monitoring, including, but not limited to patients who are at risk of seizures due to status epilepticus, haemorrhage and traumatic brain injury.

Inclusion Criteria:

Intensive care CFAM is recommended but not confined to identify non-convulsive seizures and non-convulsive status epilepticus (NCSE) in critically ill patients with the following:

1. Persistently abnormal mental status following generalised convulsive status epilepticus (GCSE) or other clinically evident seizures.
2. Acute supratentorial brain injury with altered mental status. This includes traumatic brain injury, subarachnoid hemorrhage, intracerebral hemorrhage, encephalitis, acute ischemic stroke, and during and after therapeutic hypothermia following cardiac arrest.
3. Fluctuating mental status or unexplained alteration of mental status without known acute brain injury: Mental status abnormalities can include agitation, lethargy, fixed or fluctuating neurologic deficits such as aphasia or neglect, obtundation, and coma.
4. Patients requiring pharmacological paralysis and risk for seizures.
5. Clinical paroxysmal events suspected to be seizures, to determine whether they are ictal or non-ictal
6. Patients with suggested secondary brain injury e.g. those with increased intracranial pressure.
7. Monitoring of the response of seizures and status epilepticus to treatment and to a level of burst suppression

Exclusion Criteria:

1. Patients where CFAM has been requested but a routine EEG is thought to be more appropriate, eg. in cases where a routine 20 minute EEG would answer the clinical / referral question.
2. Next of kin will not be approached to consent for the patient to be enrolled into the study where clinical condition dictates that it would not be appropriate eg. imminent withdrawal of care.
3. Participants will be excluded from the study where consent is not granted or withdrawn. This may be at commencement of the study by parents of paediatric patients or next of kin of adult patients.
4. Data gained from patients who regain capacity to give retrospective consent and then withdraw will also be excluded.