What factor can enhance the effectiveness of a BVM?

Using a bag-valve-mask (BVM) effectively is crucial in providing adequate ventilation to a patient who is not breathing. Proper seal and positioning is fundamental because these two elements ensure that air is delivered efficiently to the lungs without any leaks. A good seal around the patient's mouth and nose prevents air from escaping and maximizes the volume of air that enters the lungs with each squeeze of the bag. Additionally, correct positioning of both the patient and the rescuer plays a significant role; the patient should ideally be in a supine position with the head tilted back slightly to open the airway, while the rescuer must hold the mask with a tight seal and squeeze the bag with the appropriate timing and pressure.

While the other factors mentioned may contribute to overall efficiency and effectiveness of ventilation, they do not replace the critical need for a proper seal and positioning. For instance, using the BVM only on children limits its applicability, and higher frequency of squeezes may lead to inadequate ventilation if not done with proper technique. Interruption of ventilation can result in ineffective breathing support, but it is the initial setup provided by proper seal and positioning that ultimately allows for effective and efficient use of the BVM.