When providing mouth-to-mask ventilation with supplementary oxygen, what is the first step after sealing the mask to the patient's face?

In the context of providing mouth-to-mask ventilation, the crucial step after sealing the mask securely to the patient's face is to ensure that you adequately deliver the breath. This is achieved by exhaling slowly over the ventilation port for a duration of 1.5 to 2 seconds. This specific action is vital because it allows for an effective and sufficient volume of air to enter the patient's lungs without causing excessive pressure that could lead to complications such as barotrauma.

The flow and timing of the ventilation are key in ensuring the patient receives optimal oxygenation. By exhaling slowly over the ventilation port, the rescuer can monitor the rise of the chest and make adjustments as necessary to ensure effective ventilations. This also helps to prevent over-inflation of the lungs and allows time for the air to be distributed throughout the respiratory system.

In contrast, other options focus on equipment setup or procedure initiation that must happen prior to or in conjunction with the delivery of breaths. However, the immediate priority once the mask is sealed is to ensure that the patient is receiving ventilation effectively.