Nitrous oxide is contraindicated in patients:
1. Head injury
2. With bowel obstruction
3. Pneumothorax
4. Middle ear and sinus disease
5. With upper respiratory infections
6. COPD (emphysema or bronchitis)
7. In the first trimester of pregnancy
8. With whom communication is difficult (i.e., autistic patients)
9. Having a contagious disease since it is difficult to sterilize entire tubes

All of the above

1 - 8

1,3,4,5,6,7

1,3,4,5,6,7,9

Nitrous oxide has no contraindications