Objectives: To report whether Gasfinder and Medigas give identical 8hr time weighted average (TWA) when used simultaneously in a clinical setting.
Methods: Medigas and Gasfinder were positioned together over the left lapel pocket of five right handed dentists whilst carrying out restorative procedures on 29 supine children, mean age 11⅓ years with a range of 6 years to 15 years (50% male), during 20 treatment sessions over 6 months. Complete data was only available for 11 patients over 8 treatment sessions, mean age 11⅔ years with a range of 6 years to 15 years (54% male). Nitrous oxide dosage and sedation duration was recorded; and the 8hr TWA calculated.
Results: The percentage titrated dose of nitrous oxide ranged from 25% to 50%. Mean sedation duration was 27 minutes. (range 15 minutes to 48 minutes). Medigas mean exposure level was 164, range 11 to 553. (8hr TWA). Gasfinder mean exposure level was 83, range 31 to 177. (8hr TWA).
Conclusions: 1) Calculated 8hr TWA varied according to dosimeter used. 2) Medigas gave higher readings than Gasfinder .