A nurse is assessing a 68-year-old patient on the second postoperative day following total knee replacement surgery. Which assessment finding would be the MOST concerning and require immediate intervention?

Sudden chest pain with dyspnea and anxiety suggests pulmonary embolism, a life-threatening post-op emergency requiring immediate oxygen, monitoring, and anticoagulation. Other findings are expected post-op issues manageable with standard care.

Understanding the Clinical Priority
On the second postoperative day following a total knee replacement, the most critical nursing responsibility is the early recognition of life-threatening complications. While pain, wound drainage, and local inflammation are expected findings that require monitoring, a sudden change in respiratory and cardiovascular status signals an emergency that demands immediate intervention.

Analysis of the Correct Answer (Option 3)
The sudden onset of severe chest pain accompanied by shortness of breath and anxiety is the most concerning finding. This clinical triad is highly suggestive of a pulmonary embolism (PE), a catastrophic complication often stemming from a deep vein thrombosis (DVT). Major orthopedic surgeries like total knee arthroplasty induce significant thromboembolic stress ^[2]. The Virchow triad elements—venous stasis from immobility, endothelial injury from the surgery itself, and a hypercoagulable state postoperatively—converge to create a high-risk environment for thrombus formation. A machine learning-based systematic review confirms that hospitalized patients, particularly those undergoing high-risk procedures, have a substantial risk for DVT, which can rapidly evolve into a PE ^[1]. When a thrombus embolizes to the pulmonary vasculature, it causes a sudden ventilation-perfusion mismatch, leading to acute hypoxemia, pleuritic chest pain, and a profound sense of anxiety and impending doom. This is a medical emergency requiring the nurse to immediately administer oxygen, notify the rapid response team, and prepare for further diagnostic and therapeutic interventions.

Why the Other Options Are Not the Priority

Option 1: Knee pain rated 6/10 with movement and 3/10 at rest is an expected finding on the second postoperative day. Pain management is a core nursing function, but this level of pain does not indicate a life-threatening crisis. The nurse would continue to assess pain characteristics and administer prescribed analgesics, but this does not supersede a potential pulmonary embolism.

Option 2: 50 mL of serosanguineous drainage in the surgical drain over 8 hours is a normal postoperative finding. Serosanguineous drainage is typical, and this volume does not suggest a hemorrhage or wound complication that would require immediate intervention over a suspected PE. The nurse would simply document the output and continue to monitor.

Option 4: Swelling and mild warmth around the surgical site are classic signs of local inflammation, a normal part of the healing process. While the nurse must monitor for signs of surgical site infection, which would present with increasing redness, purulent drainage, and systemic signs like fever, localized mild warmth and swelling do not constitute an immediate emergency. A retrospective analysis of TKA patients identifies risk factors for complications, but local inflammation is an expected part of the recovery trajectory, not an acute threat like a PE .

Pathophysiological Connection and Risk Amplification
The thromboembolic risk in total knee arthroplasty is not merely theoretical. The systematic review on congenital heart disease and TKA highlights a critical pathophysiological mechanism: the surgery creates a prothrombotic state that can precipitate not only standard DVT and PE but also paradoxical embolism, especially in patients with undiagnosed intracardiac shunts ^[2]. This underscores why a sudden cardiorespiratory symptom cluster must be treated as a PE until proven otherwise. The predictive model for vascular and nerve injuries further emphasizes that elderly patients, like the 68-year-old in this scenario, have an inherently higher risk profile for postoperative vascular events, making vigilant assessment for thromboembolic symptoms a top priority . While concerns like metal hypersensitivity and its impact on readmission rates are valid long-term considerations, they do not present as acute, life-threatening events requiring immediate nursing intervention . The nurse's immediate action for sudden chest pain and dyspnea is to prioritize airway, breathing, and circulation, anticipating the need for anticoagulation, thrombolytic therapy, or embolectomy based on the definitive diagnosis.