Table 1. Study of adverse events of nitrous oxide/oxygen procedural sedation and analgesia.

Study	Country	Total number of patients	Nitrous oxide: oxygen ratio	Serious adverse events, %	Minor adverse events, %	Vomiting, %
Babl et al. (2008) [13]	Australia	762	Up to 70:30	0.3	8.3	5.7
Zier & Liu (2011) [12]	USA	7,802	Up to 70:30	0.14	5.0	2.2
Pasarón et al. (2015) [9]	USA	1,058	Up to 60:40	0	1.8	0.7