What is the primary indicator of effective ventilation when using a bag-valve-mask?

The primary indicator of effective ventilation when using a bag-valve-mask is visible chest rise with each ventilation. This is crucial because the purpose of bag-valve-mask ventilation is to deliver oxygen to the lungs, and the physical movement of the chest provides evidence that air is entering the lungs effectively. When you see the chest rising, it demonstrates that the bag-valve-mask is properly positioned and functioning, allowing for adequate lung inflation.

Other indicators, like transcutaneous oxygen saturation readings, heart rate stability, and the presence or absence of breath sounds, can provide additional information about the patient's respiratory status but do not directly confirm that effective ventilation is occurring during the use of the bag-valve-mask. Therefore, while those factors may be relevant in assessing the overall condition of the patient, visible chest rise remains the most direct and immediate sign of effective ventilation.