What are the guidelines for oxygen therapy in adults?

Oxygen Therapy Guidelines for Adults

For most acutely ill adults, target an oxygen saturation of 94-98%, but for those at risk of hypercapnic respiratory failure (COPD, morbid obesity, neuromuscular disorders), target 88-92%. 1

Target Saturation Ranges

Standard Target: 94-98%

• Apply this range to most hospitalized adults without risk factors for CO2 retention 1
• This includes patients with pneumonia, heart failure, sepsis, trauma, and most acute medical conditions 1
• Recent evidence from the AARC suggests this same target applies even to critically ill patients 2

Modified Target: 88-92%

• Use this lower range for patients with known COPD, morbid obesity, cystic fibrosis, chest wall deformities, neuromuscular disorders, or bronchiectasis with fixed airflow obstruction 1
• For patients over 50 who are long-term smokers with chronic breathlessness on minor exertion, treat as suspected COPD until proven otherwise 1
• Patients with prior hypercapnic respiratory failure requiring NIV should start with 24% Venturi mask at 2-3 L/min (or 28% at 4 L/min) 1

Critical Illness Requiring Maximum Oxygen

In cardiac arrest, shock, sepsis, major trauma, drowning, anaphylaxis, or carbon monoxide poisoning, immediately start reservoir mask at 15 L/min regardless of COPD status 1

• Continue maximum oxygen until spontaneous circulation restored or reliable oximetry available 1
• Once stable with reliable readings, titrate down to maintain 94-98% target 1
• Even COPD patients in critical illness initially receive the same high oxygen, then adjust based on blood gases 1

Monitoring Requirements

Initial Assessment

• Measure oxygen saturation before starting therapy whenever possible, but never delay oxygen for critically ill patients 1
• Obtain arterial blood gases on arrival for most patients requiring emergency oxygen 1
• Record both the SpO2 and the oxygen delivery device with flow rate on every observation 1

Ongoing Monitoring

• Recheck oxygen saturation 5 minutes after starting or changing oxygen therapy 1, 3
• Stable patients require SpO2 monitoring at least 4 times daily 1
• Critically ill patients (NEWS ≥7) need continuous monitoring and may require ICU-level care 1

Blood Gas Timing

• Patients at risk of hypercapnia (88-92% target) must have repeat blood gases 30-60 minutes after starting or increasing oxygen 1
• This ensures CO2 is not rising dangerously 1
• Patients without hypercapnia risk and stable saturations in the 94-98% range do not need repeat gases unless clinically deteriorating 1

Titration Algorithm

When Saturation Falls Below Target

1. First, verify the oxygen delivery system and pulse oximeter are functioning correctly 1, 3
2. Check for disconnections, empty cylinders, or equipment malfunction 3, 4
3. If equipment intact and saturation remains low, increase oxygen per protocol 1
4. Recheck saturation after 5 minutes at the new dose 1, 3
5. If saturation fails to rise after 5-10 minutes of increased oxygen or clinical concern exists, repeat blood gases and obtain urgent medical review 1, 3

When Saturation Exceeds Target

• Reduce oxygen concentration if patient stable and saturation above target range 1
• Document the new delivery system and flow rate after 5 minutes 1
• No repeat blood gases needed when reducing oxygen in stable patients 1

Discontinuation

• Stop oxygen once patient maintains saturation within or above target range on room air for two consecutive stable observations 1, 5
• Leave the target range prescription in place to guide future management if deterioration occurs 1

Critical Pitfalls to Avoid

Oxygen Treats Hypoxemia, Not the Underlying Cause

Supplemental oxygen improves oxygenation but does not treat the cause of hypoxemia—the underlying condition must be urgently diagnosed and treated 1, 3

• Investigate for pneumonia, pulmonary embolism, heart failure, pneumothorax, pleural effusion, mucus plugging, or aspiration 3

Pulse Oximetry Limitations

• Pulse oximetry provides no information about PCO2 or pH 1
• Readings unreliable below SpO2 85% 1
• Affected by poor perfusion, cold extremities, Raynaud's phenomenon, shock, skin pigmentation, and nail polish 1
• In carbon monoxide poisoning, pulse oximetry reads falsely normal—use carboxyhemoglobin levels instead 1

Hyperoxia Risks

• Excessive oxygen in COPD patients can worsen hypercapnia 1
• Hyperoxia may increase myocardial necrosis in acute MI and has not shown benefit in stroke 6
• Recent evidence suggests even mild hyperoxia increases morbidity and mortality in ventilated critically ill patients 6

Never Delay Oxygen for Documentation

In emergencies, start oxygen immediately and document afterward 1

Training and Administration

• All staff administering oxygen must receive formal training in oxygen delivery systems and monitoring 1
• Hospitals should include oxygen therapy in mandatory training programs given the high rate of adverse incidents 1
• Only registered trained staff should adjust oxygen therapy 1
• Unregistered staff (healthcare assistants) must have clear protocols to immediately notify trained staff when saturations fall outside target range 1

Special Considerations

High-Flow Oxygen Therapy

• Consider early initiation of high-flow nasal oxygen for patients with respiratory distress 2
• May prevent escalation to noninvasive ventilation or re-intubation post-extubation 2

Humidification

• Consider humidification when oxygen flows exceed 4 L/min 2

Positioning

• Elevate head of bed 15-30 degrees for patients with desaturation when supine, particularly those at risk for airway obstruction or aspiration 3