Psychomotor Responses to Independent Visual, Auditory and Tactile Electrical stimuli during Sevoflurane sedation (PRIVATES).

Background: Patient-controlled sedation has potential benefits, including rapid recovery and improved patient satisfaction. During patient-controlled sedation, the recipient presses a button to self-administer the sedative. The safety and efficacy of this method is dependent upon the dose relationships between the sedative's desired effects, its impact on the ability to press a button, and adverse effect occurrence. This study aimed to investigate the relationship between sedation, psychomotor function, and adverse effect occurrence during clinician-controlled sevoflurane sedation.

Methods: 15 healthy participants (10 males) were administered a sevoflurane dose-escalation protocol starting at 0 kPa and increasing in 0.2 kPa increments until a protocol endpoint occurred. Sevoflurane was delivered using conventional anaesthetic apparatus. At each sevoflurane dose, Richmond Agitation-Sedation Scale (RASS) and psychomotor function were assessed. Protocol endpoints included airway, respiratory, or cardiovascular compromise; agitation (RASS ≥+2); and sedation >3 h.

Results: The protocol endpoint was sedation >3 h for nine (60%) participants, agitation for five (33%) participants, and tonic movements for one (7%) participant. The median [range] sevoflurane dose was 0.4 [0.2-1.0] kPa when RASS <0 (sedation dose), 1.2 [0.6-2.0] kPa when participants were unable to complete reaction time testing (button-press dose), and 1.6 [1.2-2.2] kPa at the protocol endpoint (endpoint dose). The sedation dose was less than the button-press dose (P<0.0001), and the button-press dose was less than the endpoint dose (P=0.002).

Conclusions: Patient-controlled sevoflurane sedation is potentially feasible in a healthy population within the dose range 0.4-1.2 kPa. Concurrent reaction time monitoring could minimise the risk of agitation.