AnaConDa-S for sedation with volatile anaesthetics in intensive care

Technology

2.1 The Anaesthetic Conserving Device-S (AnaConDa-S; Sedana Medical) is a volatile anaesthetic delivery system to give isoflurane or sevoflurane to people who are mechanically ventilated, usually in an intensive care setting.

2.2 AnaConDa-S is a single-use device (replaced every 24 hours or earlier when needed). The device can be inserted into either the breathing circuit of a ventilator between the endotracheal tube and Y piece, replacing the heat and moisture exchanger (standard placement) or in the inspiratory port of the ventilator (alternative placement). Liquid anaesthetic is injected through the anaesthetic agent line, into a porous rod in the AnaConDa-S device where the anaesthetic is vaporised. The vaporised anaesthetic is then inhaled by the patient with the inspiration flow from the ventilator. With continued breathing, most of the anaesthetic agent that has not been absorbed by the lungs is exhaled and adsorbed by an active carbon filter in the device. On further inhalation, the anaesthetic is desorbed from the filter and transported back to the lungs, reducing the amount of anaesthetic agent wasted. The AnaConDa-S device also contains a bacterial and viral filter and a gas analyser port. This port is used to measure the exhalated anaesthetic concentration in minimal alveolar concentration (MAC value; a relative measure of the level of anaesthesia) or end-tidal concentration [Fet%]). Side stream or mainstream gas monitors, which can measure concentrations of carbon dioxide and anaesthetic gases, must be used to continually monitor anaesthesia. These will need to be purchased separately if not already available. AnaConDa-S is also recommended to be used with a gas scavenging system. This can be either via a passive system like the manufacturer's FlurAbsorb and FlurAbsorb-S products, or via an active scavenging system. This is usually built in the hospital system to capture volatile anaesthetics in operating theatres.

2.3 AnaConDa-S can be used with most kinds of ventilator, except high-frequency ventilators. It was launched in the UK in 2017 and is a newer version of the AnaConDa device (available in the UK since 2005), which is now only available on request in the UK. The AnaConDa-S has a lower dead space of 50 ml (compared with 100 ml in the original device) and works with tidal volumes as low as 90 ml. The lower dead space allows AnaConDa-S to be used on smaller adults or children who have smaller minute or tidal ventilation.

Care pathway

2.4 Adults who need sedation in intensive care have sedation with intravenous sedatives and analgesics, primarily propofol or midazolam with alfentanil, fentanyl or morphine. Children in intensive care usually have sedation with intravenous midazolam and morphine or fentanyl.

2.5 Volatile anaesthetics are not licensed for sedation in intensive care units but are licensed for inducting and maintaining anaesthesia in operating theatres. However, clinical experts reported that sedation is a continuum to anaesthesia. The off-label use of volatile anaesthetics in sedation is widely accepted and is not considered to be harmful. The choice of type of sedation and sedative agents to be used is made by trained clinicians.

2.6 Expert advice suggests the technology is being used in the NHS as an alternative to intravenous sedation in:

Innovative aspects

2.7 The innovative aspect is that AnaConDa-S is the only device that allows conserved delivery of inhaled anaesthetic in an intensive care setting in both adults and children.

Intended use

2.8 AnaConDa-S is intended to be used as an alternative to intravenous anaesthetics for people who need sedation and are mechanically ventilated in intensive care. The AnaConDa-S has a tidal volume working range of 200 ml to 800 ml when used in standard placement. Small tidal volume (90 ml) can be achieved when AnaConDa-S is used in the alternative placement.

2.9 AnaConDa-S is for use by healthcare professionals, trained to use inhalational anaesthetic drugs and recognise and manage any adverse effects, in an intensive care setting. In the NHS this would likely be intensivists and intensive care nurses.

Costs

2.10 AnaConDa-S is available for purchase as a pack of 6 for ***** This includes component materials for 6 patient set-ups and approximately 5 treatment days each (30 treatment days in total). The costs used in the economic modelling were:

For more details, see the website for AnaConDa-S.