What is the best practice for ensuring an airtight seal with a bag-mask?

The best practice for ensuring an airtight seal with a bag-mask involves holding the mask with an E-C clamp while lifting the jaw. This technique allows the rescuer to create a secure seal around the patient's face, which is crucial for effective ventilation.

The E-C clamp technique involves using the thumb and index finger of one hand to form the letter "E," which secures the mask against the patient's face while the remaining three fingers of the same hand are used to lift the patient's jaw. This maneuver not only helps maintain the mask's position but also opens the airway, making it easier to deliver breaths without air leakage.

Ensuring an airtight seal is vital because any gaps can lead to ineffective ventilation, reducing the amount of oxygen delivered to the patient's lungs. This technique is particularly useful in emergencies where rapid and effective resuscitation is necessary. By combining both elevation of the jaw and firm facial pressure, the rescuer maximizes the chances of successfully ventilating the patient.