After notifying the provider, the nurse should first administer oxygen at 2L/min via nasal cannula and then administer sublingual nitroglycerin. Rationale: Step 1: Administer Oxygen at 2L/min via Nasal Cannula The client's oxygen saturation has dropped from 97% to 92% on room air, which indicates potential myocardial oxygen demand exceeding supply. Oxygen therapy helps improve myocardial oxygenation, which is crucial for clients with suspected acute coronary syndrome (ACS). Step 2: Administer Sublingual Nitroglycerin The client’s chest pain has worsened (increased from 4/10 to 7/10) and is associated with shortness of breath, which suggests possible myocardial ischemia. Nitroglycerin causes vasodilation, reducing myocardial oxygen demand and improving coronary perfusion. It is a first-line treatment for suspected angina or acute coronary syndrome (ACS). Incorrect Options Step 1: Prepare the client for cardiac catheterization: While a catheterization may be necessary, immediate interventions (oxygen, nitroglycerin) take priority before an invasive procedure. Request a prescription for an increase in statin medication: Adjusting statins is a long-term strategy; it does not address the acute issue of chest pain and shortness of breath. Step 2: Request a prescription for a beta-blocker: Beta-blockers reduce heart rate and myocardial oxygen demand, but nitroglycerin provides more immediate relief for chest pain. Check a STAT cardiac troponin: A repeat troponin may be necessary, but the initial focus is on stabilizing the client’s oxygenation and relieving chest pain.