Advice
The technology
The technology
CerebAir (Nihon Kohden) is a wireless headset for continuous electroencephalography (EEG) monitoring of people who are critically ill in intensive care. It is a telemetry EEG amplifier comprising of 8 pre-gelled disposable electrodes pre-positioned on an adjustable headset. The EEG data recorded using the device is sent by Bluetooth to a local storage device (PC or other) and can be viewed remotely by a specialist within the hospital or offsite (depending on IT policy).
Innovations
The pre-positioned EEG electrodes are designed to improve speed and ease of electrode placement compared with conventional 10–20 EEG systems. It is also designed to remove the need for specialist training in EEG electrode placement. Data is transmitted wirelessly and can be viewed remotely so the patient does not have cables surrounding them. The company states that CerebAir's ease of application and wireless data transmission can help decrease time to diagnosis and decision support for people who are critically ill.
Current care pathway
In intensive care units, EEG can be used to diagnose status epilepticus and suspected ongoing seizures, and to assess brain function in people with unexplained and persistent unconsciousness. A standard EEG is a 20- to 30‑minute EEG recording. It consists of 21 electrodes that are attached to the person's scalp and connected by wires to an EEG recording machine. Some EEGs use caps or nets to hold the electrodes. Electrode locations and names follow the International 10–20 system. An EEG is usually done by a clinical neurophysiologist. When continuous EEG monitoring is used it most commonly consists of 4 to 8 electrodes and not the full 10–20 configuration. One of the experts noted that episodic EEG recordings are widely used in the NHS but not universally available, and that access to neurophysiology services across the UK can differ depending on the region. They also said that access to continuous EEG is more limited than access to standard 20- to 30‑minute EEG recordings.
The following publications have been identified as relevant to this care pathway:
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European Society of Intensive Medicine consensus statement on the use of EEG monitoring in critically ill patients (2013). The consensus recommends EEG in generalised convulsive status epilepticus and to rule out nonconvulsive seizures for people with brain injuries and people who are in a coma in intensive care without primary brain injury who have unexplained and persistent altered consciousness.
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The Critical Care Continuous EEG Task Force of the American Clinical Neurophysiology Society consensus statement on continuous EEG in critically ill adults and children (2015). It recommends critical care continuous EEG for diagnosing nonconvulsive seizures, nonconvulsive status epilepticus and other paroxysmal events, and for assessing the efficacy of therapy for seizures and status epilepticus. It also recommends considering critical care continuous EEG for identifying ischemia in people at high risk of cerebral ischemia; for assessing the level of consciousness in people having intravenous sedation or pharmacologically induced coma; and for prognosis in people after cardiac arrest.
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The Neurocritical Care Society and the European Society of Intensive Care Medicine consensus recommendations on multimodality monitoring in neurocritical care (2014). It suggests continuous EEG monitoring as the preferred method over routine EEG monitoring whenever feasible for people in a coma in intensive care without an acute primary brain condition and with unexplained impairment of mental status or unexplained neurological deficits to exclude nonconvulsive seizures.
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Kubota et al. (2018) Continuous EEG monitoring in ICU. A review article on continuous EEG monitoring in intensive care.
Population, setting and intended user
According to Egawa et al. (2020), nonconvulsive status epilepticus (NCSE) occurs in 8% to 20% of people in intensive care. People diagnosed with seizures in intensive care are more likely to have worse outcomes such as increased mortality and longer length of hospital stay. More than half of people diagnosed with nonconvulsive seizures (NCS) and NCSE in intensive care will go on to experience recurrent seizures after being discharged from hospital (Punia et al. 2015). Because of the high morbidity and mortality associated with NCS and NCSE, timely diagnostic testing and treating the underlying cause is important.
The device is intended to detect abnormal EEG patterns and seizure activity in people admitted to intensive care with suspected or known seizure activity, traumatic injury, altered or fluctuating consciousness, or post-cardiac arrest. EEG monitoring with CerebAir would be done by the emergency or intensive care team. Data can be reviewed remotely by a neurophysiologist and locally in intensive care. The company states that the technology could also be used in operating theatres but using it in this setting is not the focus of this briefing.
Costs
Technology costs
Purchasing the CerebAir system costs between £20,000 and £30,000 depending on the hardware configuration (for example, laptop or touchscreen monitor). The company states that an installation fee is included in the costs. The system also has consumable costs for the pre-gelled electrodes which are £89 per use. All costs exclude VAT. The technology comes with a 2‑year warranty, and the cost of any software updates are covered by the company. The company states that the expected lifespan of the device is between 7 and 10 years. The costs described for CerebAir do not include the cost of interpreting EEG recordings.
Costs of standard care
The cost per person for conventional EEG monitoring is £219 (NHS reference costs 2019/20, HRG AA33C). Conventional EEG monitoring refers to a standard 20- to 30‑minute 10–20 EEG done in an inpatient or outpatient setting. This includes electrode consumables or cleaning, as well as a neurophysiologist's time to get the EEG recording, interpret data and write a report. One of the experts who commented on the briefing noted that there is currently no NHS reference cost for continuous EEG. They estimate that the capital costs of a standard portable 10–20 EEG, laptop and associated software and video camera are between £10,000 and £20,000.
Resource consequences
The company states that CerebAir is currently being used in 4 NHS centres. The technology costs more than standard care but could be resource releasing if adopting the technology leads to shorter hospital stays and improved outcomes for patients through a quicker diagnosis and treatment. The technology may free up neurophysiologists' time because specialist training on electrode placement is not needed to apply the headset. But expert advice is that CerebAir will lead to more continuous EEG recordings being done and will place increased time demands on neurophysiologists who will need to interpret the data. One expert who commented on the briefing also said that some NHS sites may need additional local storage for data. Evidence shows the CerebAir monitoring is quicker to start than conventional EEG but its effect on treatment decisions, clinical outcomes and length of hospital stay has not been explored. The company states that product specific training is included in the purchase price and covers how to apply the headset and how to use the software.