Final answer:
The first action an EKG technician should take if a patient appears to be hyperventilating during an exercise stress test is to check the patient's respiratory rate.
Step-by-step explanation:
During an exercise stress test, if an EKG technician notices that a patient appears to be hyperventilating, the first action they should take is to check the patient's respiratory rate. This assessment will help in determining the severity of the patient's condition and inform the next steps to be taken. It is essential to first assess the patient's current state before proceeding to actions like administering oxygen, slowing down, or stopping the test. Hyperventilating can result from various factors including stress, anxiety, or underlying medical conditions, and checking the respiratory rate is crucial for accurate diagnosis and treatment.