10.5 Oxygen Therapy & Airway Management Procedures
Key Takeaways
- Medical oxygen is a prescribed drug under British Thoracic Society (BTS) guidelines and must have a documented target oxygen saturation, delivery device, and flow rate.
- Target SpO2 ranges are 94–98% for most acutely ill patients and 88–92% for patients at risk of hypercapnic respiratory failure (e.g., severe COPD or morbid obesity).
- Delivery device capabilities vary: Nasal Cannulae (1–4 L/min, 24–40% FiO2), Simple Face Mask (5–10 L/min, 35–60% FiO2), Venturi Mask (2–15 L/min, precise 24–60% FiO2), and Non-Rebreather Mask (15 L/min, 60–90% FiO2).
- Non-rebreather masks require pre-inflating the reservoir bag prior to patient fitment to ensure delivery of high concentration oxygen during critical resuscitation.
- Humidified oxygen is required when high-flow oxygen (>4 L/min) is delivered for more than 24 hours or in patients with thick tracheostomy secretions to prevent airway drying.
10.5 Oxygen Therapy & Airway Management Procedures
Oxygen is one of the most frequently administered clinical therapies in healthcare. In the United Kingdom, medical oxygen is classified legally as a prescription medicine under the British Thoracic Society (BTS) Emergency Oxygen Guidelines. Because both severe hypoxaemia and uncontrolled hyperoxia carry significant clinical risks, registered nurses must understand oxygen delivery systems, target saturation ranges, titration protocols, and monitoring standards.
British Thoracic Society (BTS) Guidelines & Prescription Standards
Except in emergency life-threatening crises, oxygen must be formally prescribed on the patient’s drug chart or electronic prescribing system. A complete prescription must specify:
- Target Oxygen Saturation Range (SpO2)
- Oxygen Delivery Device
- Flow Rate (L/min) or Fractional Inspired Oxygen (FiO2 %)
Emergency Exception
In acute emergency situations (such as cardiac arrest, anaphylaxis, severe shock, major trauma, or sepsis with critical hypoxaemia), high-concentration oxygen should be administered immediately via a non-rebreather mask at 15 L/min without awaiting a prescription. A formal prescription and clinical review must be completed immediately after stabilizing the emergency.
Prescribed Target Oxygen Saturation Ranges
| Clinical Patient Group | Target SpO2 Range | Clinical Rationale |
|---|---|---|
| Standard Acutely Ill Adult Patients <br>(No risk of hypercapnic respiratory failure) | 94% – 98% | Prevents tissue hypoxia while avoiding hyperoxia-induced vasoconstriction and absorption atelectasis. |
| Patients at Risk of Hypercapnic Respiratory Failure <br>(COPD, cystic fibrosis, severe scoliosis, morbid obesity, neuromuscular disorders) | 88% – 92% | High blood oxygen abolishes the hypoxic respiratory drive in chronic CO2 retainers, leading to severe hypercapnia, respiratory acidosis, coma, and respiratory arrest. |
| Unknown Target Range in COPD Suspect | 88% – 92% | Default safety target until Arterial Blood Gas (ABG) analysis confirms absence of hypercapnia/acidosis. |
Oxygen Delivery Devices & Flow Rate Specifications
Selecting the correct delivery device depends on the severity of hypoxaemia, patient comfort, and whether precise FiO2 control is required.
1. Nasal Cannula (Prongs)
- Flow Rate: 1 to 4 L/min.
- Delivered FiO2: 24% to 40% (delivers approximately +4% oxygen per L/min above room air 21%).
- Clinical Indications: Mild hypoxaemia in stable patients; comfortable for long-term use; allows uninterrupted eating, drinking, and speaking.
- Clinical Precaution: Flow rates >4 L/min cause mucosal drying, nasal soreness, and variable FiO2 due to mouth breathing.
2. Simple Face Mask (Hudson Mask)
- Flow Rate: 5 to 10 L/min.
- Delivered FiO2: 35% to 60%.
- Clinical Indications: Moderate hypoxaemia without CO2 retention risk.
- CRITICAL Safety Rule: Simple face masks must NEVER be used at flow rates below 5 L/min. Flow rates below 5 L/min allow exhaled carbon dioxide to accumulate inside the mask cavity, leading to dangerous CO2 rebreathing.
3. Venturi Mask (Fixed Concentration Entrainment Devices)
- Flow Rate: 2 to 15 L/min (varies by color-coded barrel valve).
- Delivered FiO2: Precise fixed concentrations of 24%, 28%, 35%, 40%, or 60%.
- Clinical Indications: Patients with COPD or hypercapnic respiratory failure who require exact, titratable oxygen percentages regardless of breath rate or depth.
| Venturi Valve Color | FiO2 Percentage | Minimum Oxygen Flow Rate |
|---|---|---|
| Blue | 24% | 2 L/min |
| White | 28% | 4 L/min |
| Yellow | 35% | 8 L/min |
| Red | 40% | 10 L/min |
| Green | 60% | 15 L/min |
Note: The total gas flow delivered to the patient (oxygen plus entrained room air) must exceed the patient’s peak inspiratory flow rate to maintain precise FiO2.
4. Non-Rebreather Reservoir Mask (High-Concentration Mask)
- Flow Rate: 15 L/min (minimum 10 to 15 L/min).
- Delivered FiO2: 60% to 90%.
- Mechanism: Equipped with a 1-litre oxygen reservoir bag and one-way valves. One-way valves prevent room air entrainment during inhalation and prevent exhaled gas from entering the reservoir bag during exhalation.
- Essential Nursing Step: The nurse MUST manually pre-inflate the reservoir bag with oxygen before placing the mask over the patient’s nose and mouth. Ensure the bag remains at least one-third to one-half full during inspiration.
Humidification, Tracheostomy & Clinical Monitoring Protocols
Humidified Oxygen Therapy
Dry compressed oxygen gas can dehydrate respiratory mucous membranes, impair mucociliary clearance, and cause sputum impaction. Humidification (via sterile water bubble bottles or heated humidifiers) is required when:
- High-flow oxygen (>4 L/min) is administered for more than 24 hours.
- Delivering oxygen directly to artificial airways (e.g., tracheostomy tubes or endotracheal tubes).
- Patients present with thick, tenacious secretions or respiratory tract infection.
Nursing Assessment & Arterial Blood Gas (ABG) Monitoring
- Continuous/Regular SpO2 Monitoring: Measure via pulse oximetry; document target saturation alignment at every vital sign check.
- Respiratory Assessment: Assess respiratory rate, depth, work of breathing, accessory muscle use, tracheal position, and breath sounds.
- Arterial Blood Gas (ABG) Analysis: Required for critically ill patients or those at risk of hypercapnia. Key normal parameters:
- pH: 7.35 – 7.45
- PaO2: 11.0 – 14.4 kPa (80 – 100 mmHg)
- PaCO2: 4.7 – 6.0 kPa (35 – 45 mmHg)
- HCO3-: 22 – 26 mmol/L
- Titration Protocol: Once SpO2 is stable within target range, gradually titrate oxygen down to the lowest flow rate necessary to maintain target saturations. Discontinue oxygen when stable on room air.
Safety Precautions in Oxygen Delivery
- No Smoking or Naked Flames: Oxygen strongly supports combustion; post warning signs in clinical areas.
- Cylinder Handling: Secure cylinders in upright trolleys or bays; do not allow cylinders to lie loose or fall.
- Oil/Grease Restriction: Never apply oil, grease, or alcohol-based hand rub near oxygen regulators or valves due to explosive ignition risks.
Under British Thoracic Society (BTS) emergency oxygen guidelines, what is the target oxygen saturation (SpO2) range for a patient with severe COPD at risk of hypercapnic respiratory failure?
When preparing to administer emergency high-concentration oxygen using a non-rebreather reservoir mask at 15 L/min, what essential nursing action must be performed prior to placing the mask on the patient?
Why is it unsafe to run a simple face mask (Hudson mask) at an oxygen flow rate below 5 L/min?
A patient with acute exacerbation of COPD requires an exact, titratable fractional inspired oxygen (FiO2) concentration of 28%. Which delivery device and settings should the nurse select?
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