Anaesthetic machines dispense a mixture of gases and vapours in varying proportions to control a patient's level of consciousness during surgery. Anaesthetic machines such as this one performed four essential functions: a) providing oxygen; b) accurately mixing anaesthetic gases and vapours; c) enabling patient ventilation; and d) minimising anaesthesia-related risks to patients and staff. The MIE everseal mask is particularly interesting as it had an innovative design that provided a significantly better airtight seal than its predecessors.