What further workup is indicated for a hospitalized patient with mild interval worsening of lung aeration on chest x-ray, likely with a respiratory condition such as pneumonia or COVID-19?

Further Workup for Hospitalized Patient with Mild Interval Worsening on Chest X-Ray

For a hospitalized patient with mild interval worsening of lung aeration on chest x-ray in the context of suspected pneumonia or COVID-19, imaging is indicated to assess for disease progression or secondary complications, and you should obtain additional diagnostic studies to evaluate for alternative diagnoses and complications that may alter management. 1

Immediate Imaging Assessment

Obtain chest CT if the patient demonstrates clinical worsening or if you need to evaluate for complications. 1

• The Fleischner Society guidelines strongly recommend imaging for patients with COVID-19 and evidence of worsening respiratory status, with 93-96% consensus among expert panelists 1
• CT is superior to chest x-ray for detecting pulmonary embolism, which is a known complication of COVID-19 that can present with worsening respiratory status 2
• CT provides better characterization of ground-glass opacities, consolidation patterns, and can identify alternative diagnoses such as superimposed bacterial pneumonia, heart failure, or pulmonary embolism 1
• In resource-limited settings where CT access is constrained, serial chest x-rays are acceptable for monitoring, but CT should be obtained if features suggest respiratory worsening 1

Laboratory Workup

Obtain arterial blood gas analysis to accurately assess oxygenation status and acid-base balance. 2, 3

• SpO2 monitoring alone can be misleading—arterial blood gas provides PaO2, pH, and PaCO2 measurements that are critical for management decisions 3
• ABG is particularly important if the clinical condition appears worse than SpO2 suggests, or if there is concern for hypercapnia 4
• Calculate the A-a gradient to differentiate between hypoventilation, V/Q mismatch, shunt, or diffusion impairment 3

Repeat or perform COVID-19 testing if not already done or if initial testing was negative with high clinical suspicion. 1

• False-negative COVID-19 testing is more prevalent in high pretest probability circumstances, and repeat testing is advised if available 1
• The Fleischner Society achieved 100% consensus that COVID-19 testing is indicated in patients incidentally found to have findings suggestive of COVID-19 on CT 1

Obtain inflammatory markers and complete blood count to assess disease severity and identify secondary bacterial infection. 2

• Elevated inflammatory markers can help distinguish COVID-19 progression from bacterial superinfection 5
• Secondary bacterial pneumonia and ventilator-associated pneumonia are common complications in COVID-19 patients, occurring in approximately 48% of mechanically ventilated patients 5

Assessment for Complications

Evaluate for pulmonary embolism with CT pulmonary angiography if clinically indicated. 2

• Pulmonary embolism is a recognized complication of COVID-19 and should be considered in patients with worsening respiratory status 2
• The Journal of the American College of Cardiology recommends monitoring for this complication in COVID-19 patients with pleural effusions or worsening dyspnea 2

Assess for cardiac involvement with echocardiography if there are signs of heart failure or fluid overload. 2

• COVID-19 can cause myocardial injury leading to heart failure, which may present with worsening respiratory status 1
• Bilateral pleural effusions in COVID-19 may indicate cardiac involvement or fluid overload 2

Screen for pneumothorax or pneumomediastinum, particularly in patients requiring mechanical ventilation or with underlying malignancy. 6

• These complications occur in approximately 1% of hospitalized COVID-19 patients but carry significantly higher mortality (55% vs 25%) 6
• Patients with pneumothorax/pneumomediastinum require invasive mechanical ventilation more frequently (79% vs 47%) 6

Respiratory Function Monitoring

Measure respiratory rate immediately—a rate >30 breaths/min requires urgent escalation even with adequate SpO2. 4, 3

• Respiratory rate and work of breathing are crucial parameters that may indicate deterioration before oxygen saturation falls 4
• The International Journal of Surgery defines severe respiratory distress as respiratory rate >30 breaths/min 2

Monitor oxygen saturation continuously with target SpO2 94-98% for most patients, or 88-92% for those at risk of hypercapnic respiratory failure. 4, 3

• The British Thoracic Society recommends starting oxygen when SpO2 falls below 92%, with strong recommendation for oxygen when SpO2 <90% 4
• Repeat ABG 30-60 minutes after initiating oxygen to confirm adequate response and ensure PaCO2 is not rising 3

Common Pitfalls to Avoid

• Do not rely solely on chest x-ray for detecting complications—CT is far superior for identifying pulmonary embolism, early interstitial changes, and subtle consolidations 2, 7
• Do not assume stable SpO2 means stable disease—respiratory rate, work of breathing, and clinical appearance are equally important indicators of deterioration 4, 8
• Do not order daily chest radiographs in stable patients—the Fleischner Society achieved 83% consensus against daily chest radiographs in stable intubated COVID-19 patients 1
• Do not dismiss the possibility of secondary bacterial infection—ventilator-associated pneumonia occurs in nearly half of mechanically ventilated COVID-19 patients and significantly worsens outcomes 5

Disease Evolution Considerations

Recognize that COVID-19 pneumonia evolves over time with changing pathophysiology. 8

• Early disease is characterized by altered lung perfusion with relatively preserved lung mechanics 8
• Progressive disease develops oedema and atelectasis, increasing recruitability and potentially benefiting from PEEP 8
• Advanced unresolved disease shifts toward less reversible structural alterations and fibrosis, with decreased recruitability and lack of response to PEEP and prone positioning 8