The first step in artificial ventilation with a bag-valve mask unit in patients with no suspected trauma is to:

Placing the patient's head in a hyperextended, sniffing position is crucial for optimal artificial ventilation with a bag-valve mask. This positioning helps to align the airway structures more effectively, allowing for better air passage into the lungs. The sniffing position opens up the airway by lifting the chin and positioning the neck in such a way that it reduces resistance, which is necessary for effective ventilation.

By ensuring the patient's head is in this position before attempting to use the bag-valve mask, the rescuer can help guarantee a seal with the mask and facilitate adequate ventilation. This step is essential, especially when there is no suspicion of trauma, as it promotes a clear airway without the complications that can arise from manipulating the spine or neck. Effective airway management relies heavily on proper positioning to achieve the best outcomes in ventilating the patient.