Final answer:
During CPR, an increase in ETCO₂ suggests improvements in perfusion, indicating that CPR should be continued as normal. It is critical, however, to keep reassessing the patient's condition.
Step-by-step explanation:
During CPR, if a patient's ETCO₂ rapidly changes from 12 to 20mmHg, the appropriate action would be to continue CPR as normal. An increase in ETCO₂, which stands for end-tidal carbon dioxide, can indicate that cardiac output is improving due to the chest compressions. Since ETCO₂ is a measure of how effectively carbon dioxide is being expelled from the lungs and thus, a marker of perfusion, a rising number suggests that CPR quality is good and should be maintained. It is vital, however, to continuously monitor the patient and reassess if conditions change or if directed by advanced medical guidance. CPR should be performed until the patient regains spontaneous contractions or is declared deceased by an experienced healthcare professional.