Oxygen Therapy Basics

CNA Responsibilities in Oxygen Therapy Delivery

Oxygen therapy is the administration of oxygen at concentrations greater than those found in ambient air (21%) to treat or prevent hypoxemia (low blood oxygen) and ensure adequate tissue oxygenation^[1]. As a CNA, you play a vital role in safely maintaining oxygen delivery systems, monitoring patients for signs of respiratory distress, and recognizing complications. Mastery of oxygen basics is a high-yield exam topic and essential for safe bedside care^[2].

Core Clinical Terminology for Oxygen Delivery

• Hypoxemia: Low oxygen level in the blood (PaO₂ < 60 mmHg or SpO₂ < 90%)^[3].
• Hypoxia: Inadequate oxygen supply at the tissue level; can occur even with normal SpO₂.
• Flow rate: Amount of oxygen delivered per minute (e.g., 2 L/min), measured in liters per minute (L/min).
• FiO₂: Fraction of inspired oxygen (0.21 = room air; 1.0 = 100% oxygen).
• SpO₂: Oxygen saturation measured by pulse oximetry (normal: 95–100%).
• High-flow vs. low-flow devices: High-flow devices (e.g., Venturi mask) deliver a precise FiO₂; low-flow devices (e.g., nasal cannula) deliver variable FiO₂ depending on the patient’s breathing pattern^[4].

Oxygen Delivery Devices and Setup Steps for CNAs

Oxygen Delivery Devices (Common for CNA Practice)

Steps for Setting Up a Nasal Cannula (CNA Responsibility)

1. Perform hand hygiene and identify the patient per facility policy.
2. Connect cannula to oxygen flow meter; turn to prescribed flow rate.
3. Confirm tank/outlet is “O₂ safe” – no oil, grease, or open flames nearby.
4. Place prongs in nares with tubing over ears and adjust the slider under the chin.
5. Check flow rate and that oxygen is flowing (feel or float ball).
6. Document: device type, flow rate, patient’s SpO₂, respiratory rate, and response^[1].

Hypoxia Warning Signs and Monitoring Parameters

• Hypoxia (early signs): Restlessness, anxiety, confusion, tachycardia, tachypnea.
• Hypoxia (late signs): Cyanosis (late), bradycardia, dysrhythmias, decreasing consciousness.
• Hyperventilation may accompany hypoxemia as a compensatory response.
• Use pulse oximetry to trend SpO₂; report values < 92% or changes from baseline^[3].

CNA Bedside Monitoring and Safety Verification

• Pulse oximetry: Place sensor on clean, warm finger (nail polish removed). Ensure waveform is present. Notify nurse if SpO₂ drops < 92% or patient condition changes.
• Respiratory assessment: Count rate (normal 12–20), depth, rhythm, use of accessory muscles, lung sounds (notify nurse if wheezes, crackles, or diminished).
• Skin color and mental status: Pallor, cyanosis, confusion, drowsiness may indicate hypoxia.
• Equipment check: Verify flow rate, tubing patency, and that reservoir bag (if used) is inflated. Water in tubing should be drained away from the patient.
• Safety check: “No smoking – Oxygen in use” signs; no petroleum‑based products (e.g., Vaseline) near oxygen; ensure electrical equipment is grounded^[4]sup>.

Comfort and Safety Measures During Oxygen Therapy

• Positioning: Semi-Fowler’s or High-Fowler’s (30–90°) to maximize lung expansion and comfort.
• Mouth care: Provide frequent oral care because oxygen dries mucous membranes. Use water‑based lip lubricant (never petroleum).
• Humidification: Add sterile water to humidifier bottle when flow > 2 L/min via nasal cannula.
• Encourage coughing/deep breathing every 2 hours to prevent atelectasis.
• Patient education: Explain why oxygen is important; keep cannula/mask in place; do not adjust flow yourself. Report any difficulty breathing or nose bleeds.
• Report immediately: Increased work of breathing, SpO₂ below prescribed target, chest pain, or change in level of consciousness^[1].

Oxygen Safety: Fire Risk and Complication Prevention

Fire Safety (Critical for Exams)

• Oxygen supports combustion – never allow smoking, open flames, or sparks in rooms where oxygen is in use.
• Post “No Smoking” signs at the door and in patient’s room.
• Do not use electrical devices that may produce sparks (e.g., razors, heating pads) near oxygen.
• Keep oxygen tank upright and secured in a stand to avoid falling and valve damage.
• Store extra tanks in well‑ventilated areas away from heat sources^[4].

Complications

• Oxygen toxicity: Prolonged high FiO₂ (>0.60 for > 24–48 hours) can damage lung tissue; CNA should report any chest pain, nonproductive cough, or dyspnea.
• Absorption atelectasis: High FiO₂ can denitrify alveoli, causing collapse; encourage deep breathing.
• CO₂ narcosis (especially in COPD): High‑flow oxygen can suppress hypoxic drive; use controlled low‑flow devices (Venturi or ≤2 L/min nasal cannula) per order^[3].
• Drying of mucous membranes: Prevent with humidification and oral care.
• Skin breakdown: Inspect nares and ears from tubing pressure; pad tubing if needed.

Critical Concepts and Memory Aids for CNA Exam

• Know the flow‑rate limits: Nasal cannula max = 6 L/min (FiO₂ ~44%); non‑rebreather requires ≥10 L/min to keep bag inflated.
• “Hypoxic drive” concept is a classic exam question: COPD patients rely on low O₂ to stimulate breathing; always start with low FiO₂ (e.g., 1–2 L/min or Venturi 24–28%).
• Oxygen is a medication – only a provider orders flow rate and device. The CNA never adjusts settings unless directed.
• SpO₂ target for most patients is 92–98%; for COPD target often 88–92%^[3].
• Memory aid: “A PVC pipe for oxygen safety” = Patency, Verify flow, Connections tight, Position (upright), Inflation of bag (if applicable), Patient teaching, Equipment checks.
• CNA cannot diagnose – but must report signs of hypoxia immediately.
• Practice reviewing equipment before the exam: identify flow meter types (pressure-compensated vs. Bourdon gauge).

References & Sources

1. Potter PA, Perry AG, Stockert PA, Hall AM. Fundamentals of Nursing. 10th ed. Elsevier; 2020. Chapter 28: Oxygenation. https://www.ncbi.nlm.nih.gov/books/NBK610832/
2. Nurse Assist, LLC. Certified Nursing Assistant Training Manual. Current edition (2021). Section 5: Basic Nursing Skills – Oxygen Therapy. https://www.ncbi.nlm.nih.gov/books/NBK593208/
3. Kacmarek RM, Stoller JK, Heuer AJ. Egan’s Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021. Chapters 40, 43. https://shop.elsevier.com/books/egans-fundamentals-of-respiratory-care/kacmarek/978-0-323-51112-4
4. Centers for Disease Control and Prevention (CDC). “Oxygen Safety: For Healthcare Providers.” Last reviewed January 2020. https://www.who.int/teams/health-product-policy-and-standards/assistive-and-medical-technology/medical-devices/oxygen
5. American Red Cross. Certified Nursing Assistant Training Handbook. 2022 edition. “Oxygen Therapy and Vital Signs.” https://www.redcross.org/take-a-class/cna-training