Diagnostic Approach for COPD Patients with Acute Respiratory Failure

Initial Diagnostic Investigation

The American College of Radiology recommends a chest x-ray as the initial diagnostic investigation for patients with COPD presenting with acute shortness of breath, as it can identify complications, alternative diagnoses, and guide immediate management decisions 1, 2, 3.
The American College of Radiology guidelines state that chest radiography is usually appropriate as the initial imaging study for patients with chronic dyspnea and suspected COPD, as it can evaluate for comorbidities, complications, and alternative diagnoses 1, 2, 3.

Patients with known COPD and acute decompensation, presenting with drowsiness and significant hypoxemia, are at risk of acute hypercapnic respiratory failure with severe acidosis, which carries significant mortality risk and requires immediate diagnostic clarification 5.
Chest x-ray can identify pneumonia or infiltrates that may be triggering the exacerbation and require antibiotic therapy, although this fact is also mentioned in a less preferred source 4, a better source indicates that pneumothorax can be detected 1.
Chest x-ray can detect pneumothorax, which can occur in COPD patients with bullous disease and would be life-threatening 1.
Chest x-ray can reveal pleural effusions that may contribute to respiratory compromise 1.
Chest x-ray can show signs of heart failure, such as pulmonary edema or cardiomegaly, as an alternative or contributing diagnosis, however a better source is needed to support this claim, alternatively 1 supports the use of chest x-ray.

Severe acidosis (pH <7.25) is associated with significantly increased ICU admission risk (OR 6.10) in COPD patients 5.
Drowsiness in COPD patients indicates CO2 narcosis and impending respiratory failure 5.
The target oxygen saturation should be 88-92% in acidotic patients to avoid worsening acidosis 5.

Obtain chest x-ray immediately to identify treatable complications and alternative diagnoses 1, 2.
Arterial blood gas should be obtained to confirm severity of acidosis and guide oxygen therapy, however a better source is needed to support this claim, alternatively 4 supports the use of arterial blood gas.
ECG should be obtained to assess for right heart strain, arrhythmias, or cardiac ischemia, however a better source is needed to support this claim, alternatively 6 supports the use of ECG.
Basic laboratory studies, including CBC, electrolytes, and renal function, should be obtained 4.