A nurse is caring for a client who sustained a closed femur fracture 48 hours ago. The client suddenly develops severe chest pain, dyspnea, and confusion. Vital signs are: temperature 101.2°F (38.4°C), heart rate 128 bpm, respiratory rate 32/min, blood pressure 88/52 mmHg, and oxygen saturation 88% on room air. What is the nurse's priority action?

Fat embolism syndrome is a life-threatening complication after long bone fractures. The priority is immediate high-flow oxygen due to severe hypoxemia (SpO2 88%). Other options are important but secondary to oxygenation.

Clinical Presentation and Underlying Pathophysiology
The client’s sudden onset of severe chest pain, dyspnea, confusion, fever, tachycardia, tachypnea, hypotension, and hypoxemia 48 hours after a closed femur fracture is a classic presentation of fat embolism syndrome (FES). Long bone fractures, particularly of the femur, create a high-risk environment for the intravasation of bone marrow fat globules into the venous circulation. These fat emboli travel to the pulmonary microvasculature, causing mechanical obstruction and triggering a biochemical cascade that damages the alveolar-capillary membrane, leading to ventilation-perfusion mismatch and severe hypoxemia [1,2]. The neurological symptoms, such as confusion, occur when fat globules or their metabolic byproducts cross into the systemic circulation, either through a patent foramen ovale or via the deformation of micro-emboli that traverse the pulmonary capillary bed, resulting in cerebral endothelial injury [1,3].

Priority Action and Clinical Reasoning
The nurse’s immediate priority is to administer high-flow oxygen. The client’s oxygen saturation is critically low at 88% on room air, indicating severe hypoxemic respiratory failure, which is the most immediate life-threatening aspect of FES. The primary pathophysiological insult in FES is a profound ventilation-perfusion mismatch and acute lung injury, which can rapidly progress to acute respiratory distress syndrome (ARDS) [1,2]. A sudden decline in peripheral oxygen saturation is often the earliest and most critical warning sign of impending circulatory collapse, as highlighted by intraoperative observations where a drop in SpO2 preceded pulseless electrical activity ^[1]. Therefore, correcting hypoxemia to support end-organ perfusion, particularly cerebral and myocardial oxygenation, takes absolute precedence over diagnostic procedures or pain management.

Analysis of Other Options
- Obtaining arterial blood gas (ABG) analysis is an important diagnostic step to quantify the degree of hypoxemia and acid-base disturbance, but it is not the first action. Delaying oxygen administration to perform an invasive procedure would allow the hypoxemia to worsen, increasing the risk of cardiac arrest or irreversible neurological damage ^[1].
- Preparing the client for a chest X-ray is a secondary intervention. While imaging may eventually show bilateral patchy infiltrates consistent with ARDS, the findings are often nonspecific and lag behind the clinical deterioration. The immediate threat is tissue hypoxia, which must be corrected without waiting for radiographic confirmation ^[2].
- Administering prescribed analgesics for chest pain is a lower priority in this scenario. The chest pain is pleuritic in nature, stemming from pulmonary parenchymal inflammation and hypoxemia, not a primary cardiac ischemic event. Administering narcotic analgesics could further compromise the client’s respiratory drive and hemodynamic stability, which are already precarious with a blood pressure of 88/52 mmHg [1,2].

Integration of Current Evidence
The diagnosis of FES remains clinical, based on criteria such as Gurd's major and minor signs, and requires a high index of suspicion in the at-risk orthopedic population ^[2]. Research into the mechanisms of FES confirms that the initial insult is a mechanical and biochemical pulmonary vascular injury, making respiratory support the cornerstone of initial management [1,4]. The case reports consistently demonstrate that a precipitous drop in oxygen saturation is the sentinel event that precedes hemodynamic collapse, reinforcing the nursing priority of immediate oxygen delivery to stabilize the patient before further diagnostic workup or therapeutic interventions are initiated [1,3].