Oxygen Therapy Nursing: Assessment, Devices, Monitoring & Safety Guide

Oxygen therapy is one of the most common interventions in clinical nursing, yet improper administration remains a leading source of preventable harm. Nurses are responsible for patient assessment before initiating O2, selecting the appropriate delivery device, titrating flow rates, monitoring response, documenting changes, and educating patients. Getting this wrong can mean anything from inadequate oxygenation to oxygen toxicity, CO2 retention in COPD patients, or fire safety incidents.

Whether you are a new graduate or an experienced nurse brushing up on best practices, this guide covers the nursing process for oxygen therapy from assessment through discharge education. It follows current clinical guidelines and addresses the real-world decisions nurses face at the bedside.

Pre-Administration Assessment

Before initiating oxygen therapy, nurses should perform a systematic assessment that informs both device selection and flow rate decisions.

Respiratory Assessment

• Respiratory rate: Count for a full 60 seconds. Normal is 12-20 breaths per minute in adults. Tachypnea (>20) may indicate hypoxemia, pain, anxiety, or metabolic acidosis.
• Breathing pattern: Note depth, regularity, use of accessory muscles, nasal flaring, or paradoxical chest movement. Labored breathing with accessory muscle use suggests significant respiratory distress.
• Lung sounds: Auscultate all lobes bilaterally. Crackles, wheezes, diminished sounds, or absent breath sounds guide clinical reasoning about the underlying cause.
• Cough and secretions: Productive vs. non-productive, sputum color, consistency, and volume all provide diagnostic information.

Oxygenation Status

• SpO2 (pulse oximetry): Obtain a baseline reading on room air when possible. Note that nail polish, poor perfusion, carbon monoxide exposure, and dark skin pigmentation can affect accuracy.
• Arterial blood gas (ABG): When available, ABGs provide PaO2, PaCO2, pH, and HCO3 values that pulse oximetry cannot. ABGs are essential for COPD patients and anyone at risk of CO2 retention.
• Clinical signs of hypoxemia: Cyanosis (late sign), restlessness, confusion, tachycardia, and diaphoresis.

Patient History

• COPD / chronic hypercapnia: This is the single most important historical factor. COPD patients who chronically retain CO2 may have a hypoxic respiratory drive. High-flow oxygen can suppress this drive, leading to hypoventilation and respiratory failure.
• Current medications: Note bronchodilators, steroids, opioids (respiratory depression risk), and sedatives.
• Allergies: Relevant for any inhaled medications that may be given alongside oxygen.

Oxygen Delivery Device Selection

Choosing the right device depends on the patient’s FiO2 requirement, breathing pattern, comfort tolerance, and clinical stability.

Device	Flow Rate	FiO2 Delivered	Best For
Nasal cannula	1-6 L/min	24-44%	Mild hypoxemia, long-term use, patient comfort
Simple face mask	5-10 L/min	40-60%	Moderate hypoxemia, short-term use
Venturi mask	4-12 L/min	24-50% (precise)	COPD patients, precise FiO2 required
Non-rebreather mask	10-15 L/min	60-95%	Severe hypoxemia, emergencies, trauma
High-flow nasal cannula (HFNC)	Up to 60 L/min	21-100%	Severe hypoxemia, post-extubation, avoiding intubation
Face tent / aerosol mask	Variable	Variable	Facial trauma, patients who cannot tolerate a mask

A nasal cannula at 1-6 L/min is sufficient for most patients with mild to moderate hypoxemia. Never set a simple face mask below 5 L/min, as exhaled CO2 can accumulate inside the mask.

Key Device Considerations

• Nasal cannula: Most comfortable for extended use. Patients can eat, drink, and talk. Flow rates above 6 L/min dry the nasal mucosa and cause discomfort. Humidification is recommended above 4 L/min.
• Simple face mask: Minimum flow of 5 L/min is required to flush exhaled CO2 from the mask. Not appropriate for COPD patients who need precise FiO2.
• Venturi mask: Uses color-coded adaptors to deliver a precise FiO2 regardless of the patient’s breathing pattern. The gold standard for COPD patients because you can set exact concentrations (24%, 28%, 31%, 35%, 40%, 50%).
• Non-rebreather: Has a reservoir bag that must remain inflated during use. If the bag deflates, the patient is not receiving adequate oxygen. Pre-fill the bag before placing on the patient.

Monitoring During Oxygen Therapy

Continuous Monitoring

• SpO2: Continuous pulse oximetry for unstable patients. Intermittent checks (every 1-4 hours) for stable patients on supplemental O2.
• Respiratory rate and pattern: Reassess at least every 4 hours and after any flow rate change.
• Mental status: Changes in alertness, confusion, or somnolence can indicate worsening hypoxemia or CO2 retention.

Red Flags to Escalate

• SpO2 below 90% despite current therapy
• Respiratory rate above 30 or below 8
• New-onset confusion or decreased level of consciousness
• Increasing work of breathing despite adequate SpO2
• SpO2 above 100% on ABG (hyperoxia in non-COPD patients is also a concern in certain populations, including neonates and post-cardiac arrest patients)

Titration Principles

Oxygen should be titrated like any other medication: to the lowest dose that achieves the therapeutic target.

Target Saturations

• General adult patients: SpO2 94-98%
• COPD / chronic CO2 retainers: SpO2 88-92%
• Acute myocardial infarction: SpO2 94-98% (avoid hyperoxia)
• Post-cardiac arrest: SpO2 94-98% (hyperoxia worsens neurological outcomes)
• Neonates: Follow unit-specific protocols, typically 90-95%

Titration Steps

1. Start at the flow rate appropriate for the clinical situation
2. Recheck SpO2 after 5 to 10 minutes
3. Adjust flow rate in increments of 1-2 L/min (nasal cannula) or change device if FiO2 needs exceed current device capabilities
4. Document each change, the rationale, and the patient’s response
5. Wean as the patient improves: reduce flow rate gradually, recheck SpO2 after each reduction, and aim to discontinue supplemental O2 when SpO2 is stable at 94% or above on room air

Documentation

Accurate documentation protects both the patient and the nurse. Every oxygen therapy entry should include:

• Date and time of initiation or change
• Clinical indication (why oxygen was started or adjusted)
• Delivery device and flow rate
• Baseline and current SpO2 and respiratory rate
• Patient response (subjective: “breathing feels easier” and objective: SpO2 improved from 89% to 95%)
• Physician order reference
• Patient education provided

Safety Precautions

Fire Safety

Oxygen does not burn, but it vigorously supports combustion. Hospital fires involving oxygen are rare but catastrophic. Nursing responsibilities include:

• Post “Oxygen in Use” signs at the bedside and room entrance
• No smoking within the immediate area (enforce with patients, visitors, and staff)
• Remove petroleum-based products from the patient’s face (petroleum jelly, oil-based lip balm). Use water-based alternatives.
• Keep electrical equipment (razors, hair dryers) away from oxygen sources
• Check that oxygen tubing is not kinked, cracked, or near heat sources
• Ensure flowmeter connections are secure (leaks create oxygen-enriched environments)

Infection Prevention

• Replace nasal cannulas and masks per facility protocol (typically every 24-48 hours or when visibly soiled)
• Change humidification water and tubing per manufacturer and facility guidelines
• Use single-patient devices; do not share between patients

Patient Education

Patients on oxygen therapy, especially those being discharged on home oxygen, need clear education on:

• Why they need oxygen: Explain in simple terms that their blood oxygen is lower than it should be and supplemental oxygen helps their body function properly.
• How to use the device: Demonstrate proper placement of nasal cannula or mask. Show them how to check the flow rate.
• Safety rules: No smoking, no open flames, keep oxygen away from stoves and heaters, store tanks upright and secured.
• When to seek help: Increased shortness of breath, persistent SpO2 below their target range, confusion, chest pain, or blue discoloration of lips or fingertips.
• Equipment maintenance: How to change the cannula, check tank levels, and troubleshoot the concentrator if applicable.

Common Nursing Interventions

Patient Refuses Oxygen

Document the refusal, educate the patient on risks, notify the physician, and monitor closely. Respect patient autonomy while ensuring they understand the consequences.

Skin Breakdown from Nasal Cannula

Inspect behind the ears and under the nares at each assessment. Use foam padding or specialized ear protectors for long-term use. Consider alternating between nasal cannula and face mask if skin integrity is compromised.

Dry Mucous Membranes

Add humidification to the oxygen delivery system, especially at flow rates above 4 L/min. Offer oral care and water-based nasal moisturizer.

Anxiety and Claustrophobia with Masks

Try a nasal cannula first if FiO2 requirements allow. For patients who need a mask, explain the purpose, provide reassurance, and check in frequently. Sedation may be appropriate in extreme cases with physician approval.

Frequently Asked Questions

What is the maximum flow rate for a nasal cannula?

Standard nasal cannulas are used at 1-6 L/min. Above 6 L/min, mucosal drying and patient discomfort become significant. If a patient needs more than 44% FiO2, switch to a face mask or higher-flow device.

Why is the SpO2 target lower for COPD patients?

Some COPD patients have chronically elevated CO2 levels and rely on hypoxic drive (low oxygen levels) to stimulate breathing. Giving them too much oxygen can suppress this drive, leading to hypoventilation, rising CO2, and respiratory failure. The 88-92% target provides adequate oxygenation without this risk.

Can a patient eat while on a nasal cannula?

Yes. This is one of the primary advantages of a nasal cannula over a face mask. The patient can eat, drink, and speak normally.

Sources

1. O’Driscoll BR, et al. “BTS guideline for oxygen use in adults in healthcare and emergency settings.” BMJ Open Respiratory Research, 2017. DOI: 10.1136/bmjresp-2016-000170
2. Siemieniuk RAC, et al. “Oxygen therapy for acutely ill medical patients: a clinical practice guideline.” BMJ, 2018. DOI: 10.1136/bmj.k4169
3. Chu DK, et al. “Mortality and morbidity in acutely ill adults treated with liberal versus conservative oxygen therapy (IOTA): a systematic review and meta-analysis.” The Lancet, 2018. DOI: 10.1016/S0140-6736(18)30479-3
4. American Association for Respiratory Care. “AARC Clinical Practice Guideline: Oxygen Therapy in the Acute Care Hospital.” Respiratory Care, 2002. Link
5. National Fire Protection Association. “NFPA 99: Health Care Facilities Code.” NFPA, 2021. Link