A nurse is caring for a 70-year-old postoperative patient with a history of COPD who underwent knee replacement surgery 2 days ago and suddenly develops acute onset of dyspnea, chest pain, anxiety, with vital signs: BP 90/60 mmHg, HR 120 bpm, RR 28/min, O2 sat 88% on room air. Which nursing action should be the nurse's FIRST priority?

This scenario describes a classic presentation of an acute pulmonary embolism (PE). The patient has multiple risk factors: advanced age (70 years), a history of COPD, and recent major orthopedic surgery (knee replacement 2 days ago). Joint arthroplasty is a well-documented high-risk procedure for venous thromboembolism (VTE), with the postoperative period representing a critical window for thrombus formation and migration [1,4]. The sudden onset of dyspnea, chest pain, and anxiety, combined with hypotension (BP 90/60 mmHg), tachycardia (HR 120 bpm), tachypnea (RR 28/min), and significant hypoxemia (O2 sat 88% on room air) signals a life-threatening cardiopulmonary event.

When applying the nursing process and Maslow's hierarchy of needs, airway, breathing, and circulation (ABCs) always take precedence. The patient’s oxygen saturation is critically low, indicating severe impairment in gas exchange. The best evidence for perioperative nursing management of hypoxemia emphasizes that the immediate priority is to optimize oxygenation and ventilation to prevent further decompensation ^[2]. Positioning the patient in high Fowler's position reduces the work of breathing by maximizing chest expansion and lung capacity, while supplemental oxygen directly addresses the hypoxemia. These are independent nursing interventions that can be initiated without delay and are foundational to stabilizing the patient before diagnostic or advanced therapeutic steps are taken.

While administering anticoagulants, preparing for a CT pulmonary angiogram, and notifying the physician are all necessary components of care for a suspected PE, they are not the first priority action by the nurse at the bedside. The nurse must first manage the immediate threat to oxygenation. A patient with an oxygen saturation of 88% is in respiratory distress and at risk for rapid deterioration, including cardiac arrest. Initiating oxygen therapy and proper positioning directly supports the patient's physiological stability, creating a safer window for subsequent diagnostic procedures like a CT scan or laboratory tests such as an arterial blood gas analysis ^[2]. This approach aligns with the evidence that nursing interventions for perioperative complications must be timed correctly, focusing on the most acute physiological derangement first ^[4].