What is the approach to managing hypoxia (low oxygen levels)?

From the Guidelines

The approach to hypoxia involves immediate oxygen supplementation while simultaneously identifying and treating the underlying cause. Start by administering supplemental oxygen via nasal cannula (1-6 L/min), simple face mask (5-10 L/min), or non-rebreather mask (10-15 L/min) depending on severity, as recommended by the BTS guideline for oxygen use in adults in healthcare and emergency settings 1. For patients with chronic CO2 retention, target SpO2 of 88-92%; otherwise aim for >94% to ensure that the actual oxygen level remains above 90% for most of the time with a 4% margin of safety to allow for variability in oxygen saturation levels, their recordings and oximeter error 1.

Key Considerations

• Position the patient upright if possible to optimize ventilation.
• Perform a rapid assessment including vital signs, respiratory effort, and auscultation.
• Order arterial blood gas analysis to determine PaO2, PaCO2, and pH, along with chest imaging to identify potential causes like pneumonia, pulmonary edema, or pneumothorax.
• If hypoxia is severe or worsening despite supplemental oxygen, consider non-invasive ventilation (CPAP or BiPAP) or intubation with mechanical ventilation.

Treatment of Underlying Causes

• Specific treatments depend on the underlying cause:
  • Bronchodilators (albuterol 2.5-5mg nebulized every 20 minutes) for bronchospasm.
  • Diuretics (furosemide 40-80mg IV) for pulmonary edema.
  • Antibiotics for pneumonia.
  • Needle decompression for tension pneumothorax.
• Hypoxia represents an imbalance between oxygen delivery and tissue demands, often due to ventilation-perfusion mismatch, diffusion limitations, hypoventilation, or right-to-left shunting, making prompt intervention essential to prevent organ damage.

Weaning and Discontinuation of Oxygen Therapy

• Weaning and discontinuation of oxygen therapy should be based on expert opinion in the absence of randomised trials, as stated in the BTS guideline for oxygen use in adults in healthcare and emergency settings 1.
• Most stable convalescent patients will eventually be stepped down to 2 L/min via nasal cannulae prior to cessation of oxygen therapy.
• Patients at risk of hypercapnic respiratory failure may be stepped down to 1 L/min (or occasionally 0.5 L/min) via nasal cannulae or a 24% Venturi mask at 2 L/min as the lowest oxygen concentration prior to cessation of oxygen therapy.

From the Research

Approach to Hypoxia

• The approach to hypoxia involves the use of oxygen therapy to reverse hypoxemia, with the goal of maintaining adequate oxygenation without causing hyperoxemia 2.
• Current recommendations include monitoring peripheral oxygen saturation (SpO2) as a surrogate for arterial oxygen saturation (SaO2), initiating oxygen only when the lower SpO2 threshold is crossed, titrating the delivered oxygen fraction to maintain SpO2 within a target range, and stopping oxygen supply when the upper limit of SpO2 is surpassed 2.
• The use of high-flow nasal cannula oxygen therapy has been shown to be effective in preventing desaturation during tracheal intubation of intensive care patients with mild-to-moderate hypoxemia 3.
• Non-invasive ventilation and high-flow oxygen therapy have been compared in terms of their ability to prevent severe hypoxemia during intubation, with no significant difference found between the two techniques 4.
• Oxygen therapy is a crucial treatment method for maintaining vital signs in patients in the intensive care unit, with current research trends focusing on conservative oxygen therapy, high-flow nasal oxygen therapy, and comparisons of high- and low-oxygenation strategies 5.

Oxygen Therapy

• Oxygen therapy should be started when SpO2 is ≤88% for patients at risk of oxygen-induced hypercapnia, and stopped when SpO2 is >92% 2.
• For patients without risk factors, oxygen therapy should be started when SpO2 is ≤92% and stopped when SpO2 is >96% 2.
• High-flow oxygen should only be used in a few diseases such as carbon monoxide poisoning, cluster headaches, sickle cell crisis, and pneumothorax 2.
• The use of high-flow nasal oxygen therapy has been shown to be effective in alleviating respiratory distress and reducing the need for intubation 5.

Patient Monitoring

• Patient monitoring is crucial during oxygen therapy, with the goal of maintaining adequate oxygenation without causing hyperoxemia 2, 6.
• The use of pulse oximetry to monitor SpO2 is recommended, with the goal of maintaining SpO2 within a target range 2, 3.
• Patient assessment, care, management, safety, and monitoring are all important aspects of oxygen therapy 6.