2 The technology


2.1 The Sedaconda anaesthetic conserving device‑S (Sedaconda ACD‑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. The technology conserves inhaled anaesthetics within the delivery system and any waste gas is captured by a passive or active gas scavenging system.

2.2 Sedaconda ACD‑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 sedative is injected through the anaesthetic agent line, into a porous rod in the Sedaconda ACD‑S device where the sedative is vaporised. The vaporised sedative is then inhaled by the patient with the inspiration flow from the ventilator. With continued breathing, most of the sedative 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 sedative is desorbed from the filter and transported back to the lungs, reducing the amount of sedative agent wasted. The Sedaconda ACD‑S device also contains a bacterial and viral filter and a gas analyser port. This port is used to measure the exhalated sedative concentration in minimal alveolar concentration, a relative measure of the level of anaesthesia; or end-tidal concentration. Side stream or mainstream gas monitors, which can measure concentrations of carbon dioxide and anaesthetic gases, must be used to continually monitor sedation. These will need to be purchased separately if not already available. Sedaconda ACD‑S is also recommended to be used with a gas scavenging system. This can be either by a passive system like the manufacturer's FlurAbsorb and FlurAbsorb‑S products, or by an active scavenging system. This is usually built into the hospital system to capture volatile anaesthetics in operating theatres.

2.3 Sedaconda ACD‑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 It was launched in the UK in 2017 and is a newer version of the Sedaconda ACD‑L device (available in the UK since 2005), which is now only available on request in the UK. Sedaconda ACD‑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 Sedaconda ACD‑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 The company has submitted a marketing authorisation request to the Medicines and Healthcare products Regulatory Agency for licensing isoflurane (Sedaconda) for inhaled sedation. Sedaconda isoflurane would be indicated for sedation of mechanically ventilated adults during intensive care and should only be administered by the medical device Sedaconda ACD‑S. The regulatory approval is currently under review.

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

  • people who need mechanical ventilation and who are difficult to sedate (both adults and children)

  • people who have severe bronchospasms that need mechanical ventilation (both adults and children)

  • people who need mechanical ventilation after cardiac surgery and cardiac arrest

  • people in whom intravenous access is difficult or not possible.

Innovative aspects

2.8 The innovative aspect is that Sedaconda ACD‑S allows conserved delivery of inhaled anaesthetic in an intensive care setting in both adults and children.

Intended use

2.9 Sedaconda ACD‑S is intended to be used as an alternative to intravenous sedation for people who need sedation and are mechanically ventilated in intensive care. The Sedaconda ACD‑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 Sedaconda ACD‑S is used in the alternative placement.

2.10 Sedaconda ACD‑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, intensive care nurses and other technical staff.


2.11 Sedaconda ACD‑S is available for purchase as a pack of 6 for £2,646. 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:

  • Device cost: £660 per full course per patient (10.9 days' sedation)

  • Consumables (FlurAbsorb, syringes, new fill adapter, measure line, Nafion tubing, accessories kit): £347.22 per patient

  • Multi-gas analyser: £36.61

  • Total cost of isoflurane administration: £110.78 per patient.

    For more details, see the website for Sedaconda ACD-S.

  • National Institute for Health and Care Excellence (NICE)