Background and study aims: Colonoscopy with portal inhaled methoxyflurane (Penthrox) is highly feasible with
low sedation risk and allows earlier discharge. It is unclear if subjects can return
to highly skilled psychomotor skill task shortly after Penthrox assisted colonoscopy.
We evaluated the psychomotor and cognitive effects of 15-minute inhalation of Penthrox
in adults.
Patients and methods: Sixty healthy volunteers (18 to 80 years) were studied on 2 occasions with either
Penthrox or placebo in a randomized, double-blind fashion. On each occasion, the subject’s
psychomotor function was examined before, immediately, 30, 60, 120, 180 and 240 min
after a 15-minute inhalation of studied drug, using validated psychomotor tests (Digit
Symbol Substitution Test (DSST), auditory reaction time (ART), eye-hand coordination
(EHC) test, trail making test (TMT) and logical reasoning test (LRT).
Results: Compared to placebo, a 15-minute Penthrox inhalation led to an immediate but small
impairment of DSST (P < 0.001), ART (P < 0.001), EHC (P < 0.01), TMT (P = 0.02) and LRT (P = 0.04). In all subjects, the performance of all 5 tests normalized by 30 minutes
after inhalation, and was comparable to that with placebo. Although increasing age
was associated with a small deterioration in psychomotor testing performance, the
magnitude of Penthrox effects remained comparable among all age groups.
Conclusions: In all age groups, a 15-minute Penthrox inhalation induces acute but short-lasting
impairment of psychomotor and cognitive performance, which returns to normal within
30 minutes
, indicating that subjects who have colonoscopy with Penthrox can return to highly
skilled psychomotor skills tasks such as driving and daily work the same day.
