How long should preoxygenation be administered to a casualty before using a suction device?

Preoxygenation should be administered for approximately 30 seconds prior to using a suction device. This duration is critical because it helps to maximize the oxygen saturation levels in the casualty's blood, providing them with a reserve of oxygen. This is particularly important when the airway is compromised or if the casualty is at risk of hypoxia during the suctioning process.

In this scenario, 30 seconds is a practical and effective amount of time that balances the need for adequate oxygenation with the urgency of addressing potential airway obstructions. A longer duration, such as 1 minute or 2 minutes, while beneficial in certain contexts, may not be feasible in an emergency setting where immediate action is often required. Conversely, less than 30 seconds may not provide sufficient time to achieve optimal oxygen saturation, potentially leading to adverse outcomes if suctioning is initiated too quickly. Thus, the 30-second mark strikes a crucial balance for effective preoxygenation.