Correct Answer: A

Rationale: Refractoriness is the correct term to describe the inability of cardiac cells to respond to a new stimulus while they are still in contraction from a previous stimulus. This period is essential for the heart to complete its contraction and relaxation phases without interference. Excitability refers to the ability of cells to respond to stimuli, not the inability to respond. Contractility is the force of cardiac muscle contraction, and automaticity is the ability of cardiac cells to generate electrical impulses spontaneously, which are not relevant to the described scenario.

Correct Answer: A

Rationale: The correct answer is A: Blood pressure. When a client is on dobutamine, it is crucial to closely monitor their blood pressure as dobutamine can cause significant changes in blood pressure. While heart rate is also important to monitor during this time, blood pressure is the most critical parameter to assess. Oxygen saturation and respiratory rate are also important parameters to monitor in a patient receiving dobutamine, but they are not as crucial as blood pressure in this scenario.

Correct Answer: A

Rationale: Bronchodilators are medications that relax the muscles around the airways, improving airflow and making breathing easier for patients with asthma or COPD. Corticosteroids are anti-inflammatory drugs used to reduce airway inflammation, while mucolytics help in thinning and clearing mucus. Antihistamines are used to treat allergies and not specifically to improve breathing in conditions like asthma or COPD.

Correct Answer: A

Rationale: Cardiac arrest is the correct answer. It is a sudden, unexpected loss of heart function, breathing, and consciousness, typically resulting in death if not treated immediately. Myocardial infarction (choice B) refers to a heart attack caused by a blockage in the coronary arteries. Heart failure (choice C) is a chronic condition where the heart is unable to pump blood efficiently. Atrial fibrillation (choice D) is an irregular and often rapid heart rate that can lead to complications but is not the same as cardiac arrest.

Correct Answer: A

Rationale: Anaphylaxis is the correct answer. It is a severe, potentially life-threatening allergic reaction that can lead to difficulty breathing, low blood pressure, and loss of consciousness. An asthma attack is a separate condition characterized by narrowed airways and difficulty breathing, but it is not necessarily related to an allergic reaction like anaphylaxis. Bronchospasm refers to the sudden constriction of muscles in the bronchi, leading to breathing difficulties, and is not specific to allergic reactions. Hypersensitivity is a general term for an exaggerated immune response to a substance, which may or may not manifest as severe allergic reactions like anaphylaxis.