What condition should a rescuer be vigilant for when performing BLS?

In the context of Basic Life Support (BLS), it is crucial for a rescuer to monitor for signs of effective circulation. This includes assessing the victim's responsiveness and looking for normal breathing patterns. These signs indicate that the heart is functioning properly and that blood is circulating effectively, delivering oxygen to vital organs. Recognizing effective circulation is fundamental because it guides the rescuer on whether to continue CPR or if the victim requires further medical intervention.

While other conditions such as confusion, spinal injuries, or allergic reactions are important to be aware of, they do not directly relate to the immediate effectiveness of cardiopulmonary resuscitation. The primary goal in BLS is to restore and maintain circulation until emergency medical services arrive, making the observation of responsiveness and normal breathing paramount.