The Role of Nitrous Oxide (“Laughing Gas”) in DUID Cases and Its Impact on Driving Fitness

Nitrous oxide has been used as a recreational drug for a long time, but has again gained importance in the past years. Hence, a growing number of road traffic offences involving nitrous oxide have been reported. Thirty-nine DUID cases associated with alleged nitrous oxide consumption were investigated. Quantification was performed by a validated HS-GC/MS method, using an appropriate calibration gas as a reference. Case information, especially driving and psychomotor impairments, was evaluated. Nitrous oxide was detected in 37 cases, with concentrations ranging from 0.22 to 17 mL/L (median: 3.7 mL/L). The time interval between the incident and blood sampling ranged from 38 to 144 min (median: 85 min) among all cases. Concomitant drug, alcohol and/or medication uptake was not present in 22 cases. Those cases were of particular interest for the evaluation of impairments. In addition to traffic accidents, driving impairments such as weaving, fluctuating driving speeds, and driving into oncoming traffic were observed. Besides others, impairments such as confusion, slowed coordination, lack of concentration, and vertigo were observed. Those were much more distinct during the police control and tenuous or even missing at the medical examination in most cases. The data show that effects of nitrous oxide are generally short-lasting but may nevertheless have an acute impact on driving ability. The detection in blood even more than 2 h after an incident demonstrates that nitrous oxide remains detectable in blood for a quite long period. Hence, the data will support forensic-toxicological casework.