Oxygen Therapy

Key Points

• SpO2 normal: 95–100% in healthy adults; 88–92% target for COPD patients (hypoxic drive)
• LTOT indication in COPD: Resting SpO2 88% or lower in stable condition supports long-term oxygen therapy referral
• Early hypoxia signs: Anxiety, restlessness, confusion — late signs: cyanosis, decreased LOC
• Escalation thresholds: In adults without chronic low baseline, new SpO2 below 92% warrants provider notification; below 88% indicates severe hypoxia requiring urgent intervention per policy
• Nasal cannula: 1–6 L/min → 24–44% FiO2 (4% increase per L/min); most common device
• Non-rebreather mask: 10–15 L/min → 60–80% FiO2; reservoir bag must never fully deflate
• Venturi mask: COPD indication — delivers precise FiO2 (24–60%); avoid high O2 in COPD
• Oxygen safety: Not flammable itself but accelerates combustion — no open flames, petroleum products
• Oxygen-enriched environments increase ignition risk from electrical sparks and static-producing materials, so home/hospital equipment safety checks are required.

Oxygenation Concepts

Pulse Oximetry (SpO2)

SpO2 estimates hemoglobin oxygen saturation noninvasively via light absorption through tissue. Each hemoglobin molecule can bind up to four oxygen molecules, and pulse oximetry indirectly estimates this saturation from optical signal changes. Finger-probe pulse oximetry is used across settings, from home checks to continuous hospital monitoring in high-acuity units.

Normal values:

• Healthy adults near sea level: commonly in the mid-to-high 90s (often about 94-98% in many references)
• COPD/chronic respiratory conditions: 88–92% (some chronic retainers/emphysema contexts may be managed near 88–90% per order and policy)
• Long-term oxygen therapy (LTOT) consideration in stable COPD: SpO2 ≤88% at rest
• At higher altitude, baseline SpO2 may be lower than sea-level expectations and should be interpreted in clinical context.

Inaccuracies — SpO2 requires clinical judgment alongside the reading:

Cause	Effect	Intervention
Motion artifact	False readings	Ensure patient still; use earlobe/forehead probe
Poor peripheral perfusion	Low reading	Warm extremity; use forehead/earlobe probe
Nail polish	Inaccurate reading	Remove polish before probe placement
Carbon monoxide poisoning	Falsely HIGH reading	ABG required for accurate assessment
Severe anemia	Normal SpO2 despite inadequate O2	ABG — SaO2 can be normal with low hemoglobin

Arterial Blood Gas (ABG)

More accurate than SpO2 — not affected by hemoglobin levels. Drawn from radial artery.

ABG Component	Normal Range
pH	7.35–7.45
PaO2 (partial pressure of oxygen)	80–100 mmHg
PaCO2 (partial pressure of CO2)	35–45 mmHg
HCO3 (bicarbonate)	22–26 mEq/L
SaO2 (calculated O2 saturation)	95–100%

See respiratory-acidosis and fluid-electrolyte-regulation-by-organs for acid-base interpretation.

Hypoxia vs. Hypercapnia

Hypoxia — reduced tissue oxygenation:

• Early signs: Anxiety, restlessness, confusion, tachycardia, tachypnea
• Late signs: Cyanosis (lips and oral mucosa), decreased LOC, decreased SpO2
• Chronic sign: Clubbing of fingertips (gradual enlargement)

Hypercapnia — elevated PaCO2 (>45 mmHg):

• Causes: Hypoventilation, ventilation-perfusion mismatch
• Signs: Tachycardia, dyspnea, flushed skin, confusion, headache, dizziness
• Early presentation may include somnolence with reduced respiratory depth/rate even when SpO2 appears near baseline
• Leads to respiratory acidosis (pH drops as CO2 accumulates)
• Management: Treat underlying cause; BiPAP support; intubation if severe

Oxygen Delivery Devices

Device	Flow Rate	FiO2	Best Use
Nasal cannula	1–6 L/min	24–44%	Low-moderate O2; COPD long-term; allows eating/talking
Oxygen concentrator	1–6 L/min	Concentrated output (commonly up to about 96% generated O2 stream)	Home/community oxygen source; pulse-flow and continuous-flow options
Simple face mask	6–10 L/min	28–50%	Moderate O2 needs; never below 6 L/min (CO2 rebreathing)
Non-rebreather mask	10–15 L/min	60–80%	High-acuity; spontaneously breathing patients needing high O2
Partial rebreather mask	10–15 L/min	35–50%	Allows some exhaled air mixing
Venturi mask	Varies by adaptor	24–60% (precise)	COPD — controlled FiO2 to avoid O2-induced hypercapnia
High-flow nasal cannula	Up to 60 L/min	Up to 100%	Critical care; heated/humidified; set up by respiratory therapist
Oxymask	1–15 L/min	About 24–90%	Open-design mask that supports communication and oral intake tasks
Oxymizer	Up to 15 L/min	Device dependent	Reservoir cannula that may maintain saturation at lower flow demand

Nasal Cannula

• Most common oxygen device; appropriate for stable patients
• 4% FiO2 increase per L/min (1 L/min = 24%, 6 L/min = 44%)
• Add humidification for hospitalized patients receiving >4 L/min or long-term therapy
• Position nasal prongs downward along the natural nares angle and secure tubing to limit dislodgement during sleep/activity.
• Limitations: Ineffective for mouth breathers; nasal polyps; deviated septum
• Skin breakdown risk: Nares and over ears — apply padding per agency policy
• If lubricant is needed for dryness, use water-based products per policy; petroleum-based lubricant is contraindicated because of combustion risk and exogenous lipoid-pneumonia risk.

Non-Rebreather Mask

• One-way valves direct exhaled CO2 out through exhalation ports; patient inhales only from reservoir bag
• Inflate the reservoir bag before placing the mask, then maintain at least partial inflation during inspiration (commonly about one-third minimum).
• Reservoir bag must remain inflated — complete or progressive deflation indicates system failure requiring immediate intervention
• Delivers highest noninvasive O2 concentration; use for patients in significant respiratory distress
• Treat interrupted gas flow as a high-risk event because one-way-valve configuration can rapidly increase suffocation risk.

Venturi Mask

• Specific adaptors set precise FiO2 regardless of flow meter reading — consult respiratory therapist before adjusting
• Preferred for COPD to prevent suppressing hypoxic respiratory drive
• Flow rate does not correspond directly to FiO2 — use adaptor-specific guidelines
• Adapter entrainment design determines air:oxygen mixing ratio (higher FiO2 uses lower air:oxygen ratio), so adapter selection is the primary FiO2 control point.

Portable Oxygen Tanks and Concentrators

• For transport, verify tank level, valve status, and ordered flow setting before leaving the unit and after arrival.
• Use approved tank holders during transport and keep cylinders secured upright (never loose on a patient bed).
• Move portable oxygen cylinders by pushing a secured cart/holder rather than pulling unsupported equipment.
• For compressed-cylinder transport planning, estimate duration using minutes remaining = cylinder pressure (psi) x tank factor / flow (L/min) and keep a safety reserve for delays.
• Common compressed-cylinder factors used in many facilities are approximately 0.28 for E cylinders and 3.14 for H cylinders (verify local policy/equipment labeling).
• For portable liquid-oxygen units, keep the pack upright; if the unit tips and hissing/vapor appears, return it upright immediately and allow it to settle in a well-ventilated area.
• A common liquid-oxygen duration approach is minutes remaining = (container weight in lb x 344) / flow (L/min); one liter of liquid oxygen weighs about 2.5 lb.
• Home/portable concentrators extract nitrogen from room air and may run as pulse flow (inhalation-triggered) or continuous flow.
• Pulse-flow concentrators are often lighter because oxygen delivery is triggered only during inhalation.

Nursing Assessment

Before Initiating Oxygen Therapy:

• Obtain brief focused respiratory history (home O2, CPAP/BiPAP use, COPD/asthma history)
• Assess airway patency, respiratory rate, lung sounds, SpO2, cyanosis
• Treat dyspnea as a subjective symptom; severe breathlessness can be present even when respiratory rate or SpO2 appears less abnormal.
• History of COPD → consider Venturi mask (controlled FiO2)
• Nonemergency: typically begin nasal cannula at 1–2 L/min and titrate
• Verify oxygen prescription unless emergent rescue care is required
• In acute hypoxia emergencies, initiate oxygen immediately per agency ABC protocol even before a provider order when policy allows, then notify provider/RT/rapid response after stabilization steps are started.
• Titrate to the ordered saturation goal for that patient (for example, maintain SpO2 above 90% when specified in standing orders).
• Document baseline respiratory rate, heart rate, blood pressure, and oxygen saturation before titration

During and After Administration:

• Reassess SpO2 within minutes of initiation — if no improvement, escalate intervention
• In adults without chronic low baseline, treat new SpO2 below 92% as escalation trigger; SpO2 below 88% indicates severe hypoxia requiring urgent response per policy
• If dyspnea worsens with saturation below patient baseline, remain with the patient during initial rescue oxygen response while arranging additional team support.
• Reassess respiratory rate, dyspnea severity, and SpO2 during the first minutes of ambulation or exertion because hypoxemia may be activity-induced.
• During dyspnea-focused reassessment, include speech tolerance (sentences/phrases/words), anxiety level, chest-pain screening, and aggravating/relieving factors.
• If exertional SpO2 falls below the ordered target, titrate oxygen within active orders/protocol and document flow changes with distance and tolerance response.
• Monitor skin integrity at pressure points: nasal cannula — nares and over ears; face masks — chin and cheeks
• Monitor for signs of worsening — if deteriorating, activate rapid response
• For COPD patients: monitor for CO2 retention if high FiO2 delivered — ABG may be ordered
• Notify provider promptly when the ordered oxygen range fails to maintain target saturation during activity or respiratory distress worsens.
• Confirm flow meter remains at ordered dose and humidification is applied when indicated to reduce mucosal drying
• For HFNC, verify heated humidification comfort settings (commonly body-temperature range) and reinforce that mouth-closed breathing can improve the intended positive-pressure support effect.
• Ensure oxygen continuity during transport and evaluate tolerance after each transfer
• If tolerated, switch from mask to nasal cannula during meals to support intake while maintaining oxygenation
• Evaluate and document therapy effectiveness using objective trends (vitals, SpO2, respiratory effort) and symptom response

Special Populations:

• Children: Age-appropriate equipment sizes; tape tubing to face if needed; pulse oximeter on palm/foot for infants
• Older adults: Ensure extension tubing reaches bathroom; coil excess tubing to prevent falls; assist with ambulation

Safety Precautions

Oxygen Safety

Oxygen is not itself flammable but significantly accelerates combustion of other materials.

• No open flames, smoking, or lit candles in room
• Keep oxygen equipment at least 5 ft from open flames or heat sources
• No petroleum-based lubricants near oxygen equipment
• Keep tanks secured upright; ensure adequate supply before transport
• Keep electrical equipment in safe working order and avoid spark-producing devices/materials near oxygen delivery (for example some razors, hair dryers, or static-generating fabrics)
• Post “Oxygen in Use” signs per agency policy
• Keep a working fire extinguisher nearby and consider notifying the local fire department about home oxygen use
• For home concentrators, avoid extension cords and place the unit in a ventilated area with about 12-18 inches of wall/drape clearance

Patient Education

• Inhale through nose with slow, deep breaths; exhale through mouth
• Nasal cannula can remain in place during eating and talking
• Report any sensation of worsening shortness of breath immediately
• Do not adjust flow rate without healthcare provider approval
• Home oxygen users: no smoking; keep equipment away from heat sources
• Extension tubing for home use — ask for assistance when ambulating to prevent falls
• Store oxygen systems in a clean, secure area away from flammable products (including aerosol sprays, oils, and grease)

Related Concepts

• respiratory-system — Anatomy of the respiratory system
• respiratory-failure — Indications for escalating oxygen therapy
• respiratory-acidosis — Hypercapnia and CO2 retention
• asthma-action-plan-and-exacerbation-management — Acute exacerbation oxygen management
• bronchodilators — Concurrent bronchodilator therapy
• evidence-based-respiratory-care — Respiratory care protocols
• prioritizing-early-deterioration-cues-in-fluid-electrolyte-care — Recognizing respiratory deterioration

Self-Check

1. A patient with COPD has an SpO2 of 93%. The nurse increases the nasal cannula from 2 L/min to 6 L/min. What concern does this raise, and what device would be more appropriate?
2. A patient on a non-rebreather mask is noted to have a completely deflated reservoir bag. What does this indicate and what is the priority nursing action?
3. A nurse checks a patient’s SpO2 after initiating oxygen and finds the reading is 99%, but the patient is confused and flushed. What condition might explain the discrepancy between SpO2 and the patient’s symptoms?