Final answer:
The most vital indication of successful PPV is improved SPo2, as it shows the bloodstream is receiving more oxygen, which is the primary objective of PPV.
Step-by-step explanation:
The most important indicator of successful Positive Pressure Ventilation (PPV) is improved SPo2, which indicates better oxygenation of the blood. When administering PPV, it's essential to monitor a patient's oxygen saturation levels to ensure they are receiving adequate oxygen. PPV aims to increase alveolar ventilation and thus enhance oxygenation and CO2 clearance.
Chest movement is also a critical sign to look for as it indicates that air is actually entering the lungs. However, chest rise alone does not guarantee effective oxygenation or ventilation. Rising heart rate can be a response to improved oxygenation, but it is not as direct an indicator as SPo2. Lastly, while the loss of cyanosis is a positive sign, it is again less immediate and subject to subjective assessment than the quantifiable measure of SPo2.