What is the ratio for N₂O:O₂ mixtures?

The correct ratio for nitrous oxide (N₂O) to oxygen (O₂) mixtures in medical applications, such as anesthesia, is often 50:50. This balanced mixture is commonly used for several reasons. First, the 50% concentration of nitrous oxide provides effective analgesia and sedation while being safe and well-tolerated by patients. Oxygen is included to ensure that the patient receives adequate oxygenation, which is vital for maintaining normal physiological functions during procedures requiring sedation.

In a 50:50 mixture, the effects of nitrous oxide, including its rapid onset and quick recovery times, are maximized, while also minimizing the risk of hypoxia (insufficient oxygen) that could occur with higher concentrations of N₂O without adequate O₂ support. This ratio is particularly favored in dental practices and for certain surgical procedures, highlighting its importance for both efficacy and safety in patient care.

Higher concentrations of nitrous oxide, such as in the other answer choices, could lead to insufficient oxygen levels in the body, while a 100% nitrous oxide setting is not viable for patient safety or physiological stability. These alternative ratios do not provide the necessary balance for safe and effective sedation.