From the Guidelines
A thorough workup for a patient with hypoxia should begin with immediate oxygen supplementation to maintain oxygen saturation above 90% while investigating the underlying cause, with a target saturation range of 94–98% for acutely ill patients not at risk of hypercapnic respiratory failure 1.
Initial Assessment
The initial assessment of a patient with hypoxia should include a comprehensive history focusing on cardiopulmonary symptoms, risk factors, and exposures. This history should be followed by a physical examination targeting respiratory, cardiac, and systemic findings.
- Key elements of the history include:
- Symptoms such as dyspnea, chest pain, or cough
- Risk factors for respiratory or cardiac disease
- Exposures to potential respiratory irritants or toxins
- The physical examination should focus on:
- Respiratory rate and depth
- Oxygen saturation
- Heart rate and rhythm
- Blood pressure
- Lung sounds and any signs of respiratory distress
Diagnostic Testing
Diagnostic testing for a patient with hypoxia should include:
- Arterial blood gas analysis to determine the severity and type of hypoxemia (whether it's associated with hypercapnia or normal/low CO2) 1
- Basic laboratory tests:
- Complete blood count
- Basic metabolic panel
- Cardiac enzymes
- D-dimer
- BNP
- Chest imaging:
- Chest X-ray
- potentially advancing to CT pulmonary angiography if pulmonary embolism is suspected
- Electrocardiogram and echocardiography to evaluate cardiac causes
- Pulmonary function tests may be valuable for chronic conditions
Ongoing Management
Throughout the workup, it is essential to continuously monitor vital signs, oxygen saturation, and respiratory status. Be prepared to escalate respiratory support from nasal cannula to high-flow oxygen, non-invasive ventilation, or intubation if the patient deteriorates.
- Monitoring should include:
- Continuous oxygen saturation monitoring
- Regular assessment of respiratory rate and depth
- Monitoring for signs of respiratory distress or failure
- Escalation of respiratory support should be based on clinical judgment and the patient's response to initial therapy.
Specialized Tests
Additional specialized tests based on clinical suspicion might include:
- Bronchoscopy
- Sleep studies
- Thoracic ultrasound
- Right heart catheterization These tests should be guided by the patient's specific clinical presentation and the results of initial diagnostic testing.
This systematic approach helps identify common causes of hypoxia such as pneumonia, pulmonary embolism, COPD exacerbation, heart failure, ARDS, or interstitial lung disease, allowing for targeted treatment of the underlying condition 1.
From the Research
Thorough Workup for Hypoxia
To thoroughly work up a patient with hypoxia, the following steps can be taken:
- Assess the patient's oxygen saturation levels and arterial blood gas (ABG) results to determine the severity of hypoxia
- Evaluate the patient's medical history, including any pre-existing respiratory or cardiac conditions that may be contributing to the hypoxia
- Perform a physical examination to assess for any signs of respiratory distress or failure
- Consider ordering imaging studies, such as a chest X-ray or CT scan, to evaluate for any underlying lung disease or other conditions that may be causing the hypoxia
Oxygen Therapy
Oxygen therapy may be necessary for patients with hypoxia, particularly those with severe chronic obstructive pulmonary disease (COPD) 2, 3, 4, 5. The goal of oxygen therapy is to increase the patient's oxygen saturation levels and reduce symptoms of hypoxia.
- Supplemental oxygen therapy (SOT) has been shown to improve survival and quality of life in patients with severe COPD and hypoxemia 2, 5
- However, the use of SOT in patients with moderate hypoxemia or exertional desaturation is less clear, and may not provide significant benefits 2, 4
- Automated oxygen administration devices may help to optimize SOT and reduce side effects 4
Alternative Oxygen Therapy Techniques
Other oxygen therapy techniques, such as high flow nasal cannula oxygen (HFNO) and supraglottic jet oxygenation and ventilation (SJOV), may be considered for patients with hypoxia, particularly those with COVID-19 6.