NCLEX-RN · Physiological Adaptation · 8 min read
Respiratory Emergencies
- Differentiate the assessment findings and pathophysiology of acute hypoxemic failure, acute hypercapnic failure, status asthmaticus, and COPD exacerbations.
- Prioritize emergency interventions and diagnostic evaluations for pulmonary embolism and thoracic trauma, including pneumothorax and flail chest.
- Apply evidence-based nursing care to clients requiring noninvasive positive-pressure ventilation and closed chest tube drainage systems.
Acute Respiratory Failure and ARDS
Acute respiratory failure occurs when the pulmonary system cannot maintain adequate gas exchange. It is categorized into hypoxemic and hypercapnic forms based on arterial blood gas values. Hypoxemic respiratory failure is generally defined as a PaO2 below 60 mm Hg on room air. When severe hypoxemia persists, characterized by a PaO2 of 60 mm Hg or less despite an FiO2 of 60% or greater, it signifies severe, refractory hypoxemia. This specific failure of arterial oxygen levels to rise despite escalating FiO2 is termed refractory hypoxemia and serves as the clinical hallmark of acute respiratory distress syndrome.
Acute hypercapnic respiratory failure involves a failure of ventilation and is generally defined by a PaCO2 greater than 50 mm Hg paired with an acute arterial pH below 7.35. In contrast, clients who have chronic hypercapnia may present with an elevated PaCO2 without acidemia because their bodies have had time to compensate. Recognizing neurologic cues is essential during clinical monitoring. Restlessness and agitation can be early signs of hypoxemia, whereas confusion may develop as hypoxemia worsens over time. Furthermore, if a client exhibiting severe respiratory distress suddenly experiences a decrease in respiratory rate, this sudden change must not be interpreted as recovery; it is a critical indicator of fatigue and impending respiratory arrest.
Clinical positioning and supportive ventilation can significantly alter outcomes in acute respiratory failure. For most clients with unilateral lung disease, positioning the healthy lung down can improve oxygenation; if the affected lung is bleeding or producing copious secretions, position it down to help protect the healthy lung. For clients experiencing ventilatory failure, noninvasive positive-pressure ventilation provides pressure support. However, noninvasive positive-pressure ventilation is generally inappropriate for clients presenting with hemodynamic instability, an inability to protect the airway, or a high risk of aspiration.
Common mistakes
- Interpreting a silent chest in an asthmatic client as a sign that bronchospasm has resolved, when it actually indicates severe, life-threatening airflow limitation.
- Routinely stripping or milking chest tube tubing to clear drainage, which dangerously spikes negative intrathoracic pressure.
- Applying high-flow oxygen indiscriminately to clients with acute COPD exacerbations rather than titrating to the target saturation of 88 to 92 percent.
- Failing to recognize that an accidental chest tube disconnection requires temporary immersion in sterile water or normal saline rather than clamping.
Key points
- Hypoxemic respiratory failure is defined by a PaO2 below 60 mm Hg on room air, while acute hypercapnic failure requires a PaCO2 greater than 50 mm Hg with an arterial pH below 7.35.
- In status asthmaticus, inhaled short-acting beta-2 agonists like albuterol are first-line, while a silent chest or a normal-to-rising PaCO2 indicates severe airflow limitation and impending respiratory failure.
- Oxygen therapy in acute COPD exacerbations must be titrated to a target SpO2 of 88 to 92 percent to prevent worsening hypercapnia from altered V/Q matching and the Haldane effect.
- Deep vein thrombosis is the leading source of pulmonary embolism, which presents with sudden dyspnea, pleuritic chest pain, and tachypnea, and is best diagnosed by computed tomography pulmonary angiography.
- Tension pneumothorax causes rising intrapleural pressure and impaired venous return; tracheal deviation may occur late or be absent, so suspected tension pneumothorax requires immediate decompression without waiting for that sign.
- Chest tube drainage systems rely on gravity drainage below chest level, normal tidaling in the water-seal chamber, and strict avoidance of routine stripping or milking.
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