Diamedica Draw-over Vaporiser: bench testing the UK Defence Anaesthesia System in the deployed environment.

Area of Science:

• Anesthesiology
• Medical Devices
• Engineering

Background:

• The Diamedica Draw-over Vaporiser 2 (DDV2) is crucial for deployed volatile general anesthesia in the UK Defence Medical Services.
• The Defence Anaesthesia System utilizes a modified 'push-over' configuration of the DDV2 with a turbine-driven ventilator.

Purpose of the Study:

• To investigate sevoflurane delivery from the DDV2 in a modified Defence Anaesthesia System configuration.
• To assess the impact of varying minute volumes (MVs), vaporiser settings, and ambient temperatures on sevoflurane output.

Main Methods:

• Tested DDV2 settings (1-4%, induction) and MVs (2-8 L/min) at 20°C and 30°C for 30 minutes.
• Conducted a supplemental 90-minute experiment simulating damage control surgery (2% setting, 6 L/min MV).
• Monitored sevoflurane delivery phases: 'wash-in' and 'maintenance'.

Main Results:

• Sevoflurane delivery exhibited a 'wash-in' phase (<5 min) followed by a 'maintenance period'.
• Output was constant at low MVs/settings; it decreased predictably at higher MVs/settings.
• At 20°C, delivery was within 20% of the set value; higher settings, MVs, and temperatures increased variation due to incomplete temperature compensation.

Conclusions:

• The DDV2 demonstrates predictable function across tested settings, MVs, and temperatures in the Defence Anaesthesia System.
• Sevoflurane delivery characteristics are comparable to standard draw-over configurations.
• The equipment proved reliable and robust, supporting its continued use for deployed anesthesia and training.