Not Medical/Legal Advice: According to a source, inhaled nitrous oxide is not detected on results of standard/routine drug screening panels. It can be detected in blood or urine shortly after exposure, but using special techniques and precautions.
Nitrous oxide's effects do not last for very long, and neither do the traces of it in the body, because it is quickly expelled through the lungs. It is not chemically-similar to any of the other drugs which are commonly tested for, and therefore it should not produce any erratic results or trigger the test as another substance.
In latest news, Holyoke Medical Center has become the first hospital in Massachusetts — and one of the first in the United States — to offer the once more commonly used nitrous oxide as an inhaled sedation choice to help relieve pain during labor. Find out more here.