What is the treatment for hypoxia?

Treatment of Hypoxia

The primary treatment for hypoxia is supplemental oxygen therapy, which should be initiated immediately for patients with severe hypoxemia (SpO2 <85%) using a reservoir mask at 15 L/min, with subsequent titration to maintain a target saturation of 94-98% in patients without risk of hypercapnic respiratory failure. 1

Initial Assessment and Management

• All patients with hypoxemia require immediate clinical assessment to identify and treat the underlying cause while providing appropriate oxygen therapy 2, 1
• Arterial blood gases (ABGs) should be checked within 1 hour of initiating oxygen therapy to assess for hypercapnia and guide further management 1
• For critically ill patients or those with shock/hypotension, arterial blood samples are preferred over capillary samples 1

Oxygen Therapy Based on Patient Risk Profile

Patients WITHOUT Risk of Hypercapnic Respiratory Failure:

• Initial treatment: Reservoir mask at 15 L/min oxygen flow for patients with severe hypoxemia (SpO2 <85%) 2, 1
• Once stabilized: Titrate down to maintain target saturation of 94-98% using:
  • Nasal cannulae at 1-6 L/min, or
  • Simple face mask at 5-10 L/min 2, 1
• If medium-concentration therapy with nasal cannulae or simple face mask does not achieve the desired saturation, change to a reservoir mask and seek senior or specialist advice 2

Patients WITH Risk of Hypercapnic Respiratory Failure:

• Initial treatment: 24% Venturi mask at 2-3 L/min or 28% Venturi mask at 4 L/min or nasal cannulae at 1-2 L/min 2, 1
• Target saturation range: 88-92% 1
• As a general principle, prevention of tissue hypoxia supersedes CO2 retention concerns 2
• If CO2 retention occurs, monitor for acidemia. If acidemia develops, consider noninvasive or invasive mechanical ventilation 2

Risk Factors for Hypercapnic Respiratory Failure

• COPD and other conditions causing fixed airflow obstruction 1
• Cystic fibrosis 1
• Neuromuscular disease or neurological conditions affecting respiratory muscles 1
• Chest wall deformities or morbid obesity 1

Special Clinical Scenarios

• For carbon monoxide and cyanide poisoning: Use hyperoxemia (highest feasible oxygen concentration) 2
• For spontaneous pneumothorax: Hyperoxemia may be beneficial 2
• For cluster headache: Oxygen therapy can be beneficial 2
• For paraquat poisoning or bleomycin lung injury: Target lower saturation of 85-88% 1
• For patients with high respiratory rates: Use Venturi mask at a flow rate exceeding their peak tidal and exertional inspiratory flow 1
• For patients with intractable breathlessness in palliative care who are not hypoxemic (SpO2 ≥92%): Oxygen therapy is not recommended 1

Long-Term Oxygen Therapy (LTOT)

• LTOT improves survival in patients with COPD and severe hypoxemia (PaO2 ≤55 mmHg) 2
• Longer duration of oxygen therapy (19 hours/day vs. 12 hours/day) improves survival in severe hypoxemia 2
• No survival benefit has been demonstrated for patients with moderate hypoxemia (PaO2 ≤69 mmHg) 2

Monitoring and Follow-up

• Record oxygen saturation, delivery system, and flow rate on the patient's monitoring chart 1
• Adjust oxygen delivery device and flow rate to maintain target saturation range 1
• Urgent clinical reassessment is required if oxygen requirements increase 1
• Consider noninvasive ventilation for patients with persistent hypoxemia despite oxygen therapy, especially those with COPD exacerbations 1

Potential Risks and Pitfalls

• Hyperoxia can cause vasoconstriction in cerebral, coronary, and systemic vasculature, potentially reducing coronary blood flow and myocardial oxygen consumption 3
• Increased production of reactive oxygen species and oxidative stress can occur with hyperoxia 3, 4
• In patients with COPD and other conditions with risk of hypercapnic respiratory failure, high-flow oxygen can worsen hypercapnia and lead to respiratory acidosis 2, 1
• The major hazard of long-term oxygen therapy is fires or explosions, which is why prescribing LTOT for current smokers is controversial 2

Algorithm for Oxygen Therapy

1. Assess patient for hypoxemia and identify underlying cause
2. Determine risk for hypercapnic respiratory failure
3. Select appropriate initial oxygen delivery device and flow rate based on risk profile
4. Obtain ABGs within 1 hour of initiating oxygen therapy
5. Titrate oxygen to maintain target saturation (94-98% or 88-92% based on risk)
6. Monitor continuously and adjust as needed
7. Consider advanced respiratory support (NIV or invasive ventilation) if patient fails to respond to oxygen therapy