Sedaconda ACD-S for sedation with volatile anaesthetics in intensive care

Experts explained that Sedaconda ACD‑S allows delivery of inhaled sedation in an intensive care setting without the need for a gas scavenging system. The alternative would be to use an anaesthetic trolley or machine used for general anaesthesia with a gas scavenger, but the clinical experts said that intensive care units are not routinely equipped with scavenging systems. The experts also said that before Sedaconda ACD‑S was implemented, patients needing inhaled sedation with vaporisers had to be transferred to operating theatres where scavenging systems for volatile anaesthetics are built into the hospital system (that is, the exhaust port of the anaesthetic circuit or ventilators are connected to the operating theatre scavenging system). The committee concluded that Sedaconda ACD‑S is an efficient delivery system for inhaled sedation in an intensive care setting not equipped with scavenging systems.

Although no clinical evidence in children was presented to the committee, a clinical expert said that Sedaconda ACD‑S has been used for 15 years in their paediatric intensive care and it is an effective way of delivering inhaled sedation. No major contraindications exist for using inhaled sedation in children, apart from malignant hyperthermia susceptibility. The EAC extrapolation of the efficacy of inhaled sedation from adults to children considered it reasonable to assume that children respond similarly to the intervention to adults. The committee accepted the assumption and concluded that Sedaconda ACD‑S is a useful option for allowing delivery of volatile sedation in children.

Six clinical studies (5 randomised controlled trials [RCTs] and 1 comparative non‑RCT) reported statistically significant differences in wake up between the intravenous sedation and the inhaled sedation using Sedaconda ACD‑S. The EAC reported that the extubation time is likely dependent on the type of sedative agent used rather than using the Sedaconda ACD‑S device itself. Nevertheless, the clinical experts agreed that using inhaled sedation delivered with Sedaconda ACD‑S leads to more predictable wake-up time in people having sedation for a long time and this is useful when patients need to be woken quickly to make clinical assessments.

The 21 studies had heterogenous patient populations that included people after cardiac surgery (9 studies), people after cardiac arrest having therapeutic temperature management (3 studies), people with acute respiratory distress syndrome (2 studies), patients with various surgical indications (2 studies), people having head and neck surgery who need a tracheostomy (1 study), people with pulmonary disorders (1 study) and people with over 12 hour (1 study) and 24‑hour sedation needs (2 studies). The committee concluded that there was uncertainty about which specific patient population would have the most clinical benefit from using inhaled sedation. But, based on expert advice, it agreed that Sedaconda ACD‑S should be an available option for delivering inhaled sedation in intensive care settings when considered clinically appropriate.

Clinical experts said that the length of stay in intensive care and the time on mechanical ventilation are outcomes that depend on a patient's underlying condition. The committee understood that this means it is particularly challenging to show evidence of benefit for length of stay in the context of a clinical study. However, clinical experts explained that using inhaled sedation can reduce the time on mechanical ventilation and shorten the time the patient stays in intensive care after extubation by some hours. The committee concluded that type of sedation used was likely to only have a small effect on the length of stay in intensive care or time on mechanical ventilation.

Clinical experts reported that during the SARS‑CoV‑2 pandemic, inhaled sedation using Sedaconda ACD‑S has been used to preserve intravenous sedative agents that could potentially be in limited supply. The committee concluded that Sedaconda ACD‑S is a useful option to spare intravenous sedative agents during unexpected emergency situations when a large number of people need mechanical ventilation such as in the recent SARS‑CoV‑2 pandemic.

The committee heard that there were no reported safety concerns around using the Sedaconda ACD‑S device. It understood that people in intensive care have highly complex needs and as such most adverse events will be because of the different medications used to achieve sedation, rather than using the Sedaconda ACD‑S device itself. The only adverse event linked to the device is blockage, which can also happen in heat and moisture exchangers at a similar rate. There are adverse events associated with using volatile anaesthetic drugs. Volatile anaesthetics are contraindicated in patients with malignant hyperthermia susceptibility. Clinical experts said that using volatile anaesthetics in pregnant women, especially in the first trimester, involves clinical judgement in the risk/benefit balance to the unborn fetus and risk to the woman. The committee concluded that using Sedaconda ACD‑S is safe.

There are other adverse events associated with using volatile anaesthesia listed in the BNF.

Clinical experts explained that there are benefits for patients when volatile sedatives are used, such as liver, lung and cardiac protection. The EAC reported better awareness quality (1 study) and lower incidence of delirium (1 study) in the Sedaconda ACD‑S group compared with the intravenous group.

The clinical experts agreed that inhaled sedation is likely to be beneficial in the following subgroups:

• people who are difficult to sedate

• people with acute bronchospasm

• people with acute respiratory distress syndrome

• people having multiple sedative agents

• people with overdose who need a fast wake up

• people who need neurological assessment after cardiac arrest

• older people at high risk of delirium

• children with resistant status epilepticus

• people with difficult intravenous access

• people with hypoxia.

While uncommon, clinical experts said that patients can be transported for additional tests or procedures within hospitals using Sedaconda ACD‑S. If transport ventilators do not have a scavenging system built in, canisters containing activated carbon, such as FlurAbsorb, can be added to the transport trolley.

The clinical experts said that the company offers face-to-face training and 3 accredited e‑learning modules for intensive care nurses and intensivists. The clinical experts noted that the company training resources were highly effective.

Volatile anaesthetic drugs are potent greenhouse gases. However, the company claims that the conservation of gases within Sedaconda ACD‑S and using scavenging systems can reduce the release of gases into the atmosphere. The company also claims that Sedaconda ACD‑S would be associated with a lower consumption of volatile sedatives compared with other delivery systems for volatile sedation. The committee was concerned about the environmental effect of increased use of anaesthetic gases and was unsure about the company claims on the efficacy of their scavenging systems. They noted that there was a lack of evidence comparing Sedaconda ACD‑S with other vaporisers used for delivering volatile sedation. Nevertheless, the committee concluded that there was potential that Sedaconda ACD‑S would minimise the release of greenhouse gases.

The committee accepted the EAC's changes to the company model, which showed that inhaled sedation delivered with Sedaconda ACD‑S was cost saving when compared with intravenous sedation. However, the committee agreed that the modelled clinical scenario comparing intravenous sedation with inhaled sedation using Sedaconda ACD‑S does not reflect the average UK duration of time on mechanical ventilation in intensive care, so has limited applicability (mean time on mechanical ventilation used in the model was 10.9 days whereas experts reported 5 days to 7 days in the UK). The committee also noted that the clinical evidence used to populate the model had substantial limitations, which affected the robustness of the model and the certainty of the results.

The committee concluded that the evidence about length of stay in intensive care and the time on mechanical ventilation reported in the post-hoc analysis from the Meiser (2021) trial was weak. Because these inputs were the key drivers that led Sedaconda ACD‑S to be cost saving, the conclusion of the economic modelling was uncertain. Despite these uncertainties, the committee noted that Sedaconda ACD‑S has a low threshold to be cost saving. The EAC's threshold analysis found that Sedaconda ACD‑S was cost saving when duration of non‑ventilated days in intensive care was only a few hours shorter than that of intravenous sedation (2.5 hours to 5 hours). The committee concluded that Sedaconda ACD‑S was likely to be the cost saving.

The committee noted that Sedaconda ACD‑S remained cost saving in all scenario analyses presented. However, the robustness of the estimates of length of stay in intensive care and time on mechanical ventilation were uncertain. The committee concluded that the uncertainty in the clinical inputs could lead to inaccuracies in the cost savings calculated.

The EAC reported that in modelling, Sedaconda ACD‑S is cost saving compared with intravenous sedation by £3,833.76 per adult patient and by £2,837.41 per child. The committee concluded that Sedaconda ACD‑S was likely to be cost saving compared with propofol or midazolam but recognised the limitations in the underpinning clinical evidence which made the size of the potential cost savings uncertain.