Dose requirements for propofol anaesthesia for dental treatment for autistic patients compared with intellectually impaired patients.

We had clinical grounds to suspect that patients with autism had greater propofol requirements during dental procedures than patients with intellectual impairment without autism. This hypothesis was tested by an audit of a standard anaesthetic technique. The audit was approved by our Hospital Ethics Committee. We compared the propofol requirements and effect using a standardised protocol during dental treatment in 56 autistic patients (age range three to 35 years) and 56 intellectually impaired patients (age range four to 42 years). Patients in each disability group were divided into three subgroups by age: six years or younger, seven to 19 years and 20 years or older. Combative patients received oral midazolam premedication, other patients received a single intravenous bolus of midazolam at induction. Otherwise, standardised propofol boluses and infusion were the only anaesthetic agents used. The propofol infusion rates of the intellectually impaired group showed significant decline with age (propofol rate of requirement mg x kg(-1) x h(-1), mean [SD]): < six years 13.6 (3.6), seven to 19 years 9.5 (3.0) (P = 0.008 cf < six years group), > 19 years group 8.5 (2.4) (P = 0.001 cf < six years group). The propofol requirement was greater in the autism group than in the intellectual disability group, and the proportion of the cases where bolus propofol administration was needed after induction was significantly higher in the autistic patient group than in the intellectually impaired patients (P < 0.002). This suggests that autistic patients have greater propofol requirements for anaesthesia during ordinary dental treatment compared with intellectually impaired patients.