Oxygen Therapy and Respiratory Care

Oxygen therapy is one of the most frequently used emergency and ongoing treatments in UAE healthcare facilities. Respiratory diseases — including asthma, COPD, and respiratory infections — are among the most common presentations in UAE hospitals, and the desert environment with its sandstorms and dust particles poses particular respiratory challenges. The DOH (UAE) examination tests your understanding of oxygen delivery systems, indications for supplemental oxygen, monitoring parameters, and the nursing management of patients with respiratory compromise. Safe oxygen therapy requires understanding both the clinical indications and the potential dangers of hyperoxia.

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🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Oxygen Therapy — When and How Much:

Condition	Target SpO₂	Initial Device
COPD (stable)	88–92%	Nasal cannula 1–2 L/min
COPD (acute exacerbation)	88–92%	Venturi mask 24–28%
Asthma (acute)	≥94%	Non-rebreather mask
Pneumonia	≥94%	Nasal cannula or mask
Cardiac arrest	98–100%	Bag-valve-mask with reservoir
Normal (no respiratory distress)	95–100%	No supplemental O₂ needed

Key Rule: In COPD, HYPOXIA KILLS before hyperoxia does — never withhold oxygen from a hypoxic COPD patient for fear of suppressing their drive. But do aim for the target range (88–92%) — not higher.

Oxygen Delivery Devices Comparison:

Device	FiO₂ Delivered	Flow Rate	Best For
Nasal cannula	24–44%	1–6 L/min	Mild hypoxia; COPD; long-term
Simple face mask	40–60%	5–8 L/min	Moderate hypoxia; short-term
Venturi mask	24–50% (precise %)	As per colour-coded adapter	COPD (precise FiO₂ control)
Non-rebreather mask	80–95%	10–15 L/min	Severe hypoxia; trauma
High-flow nasal cannula (HFNC)	21–100%	Up to 60 L/min	Acute hypoxaemic respiratory failure

⚡ Exam Tip: If a patient’s SpO₂ drops below 90%, the nurse should immediately increase oxygen, reassess, and if SpO₂ does not improve within 5 minutes, call the physician. Do not wait for the patient to look worse — use objective criteria.

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

1. Physiology of Oxygenation

Oxygen Cascade: Atmospheric air (21% O₂) → Trachea → Bronchi → Bronchioles → Alveoli → Pulmonary capillaries → Left heart → Systemic arteries → Capillaries → Tissues

At each stage, the partial pressure of oxygen decreases. At sea level:

• Atmospheric PAO₂ = 150 mmHg (at rest, breathing air)
• Alveolar PAO₂ = 100 mmHg
• Arterial PaO₂ = 80–100 mmHg
• Venous PvO₂ = 35–45 mmHg

Hypoxaemia vs Hypoxia:

• Hypoxaemia = low arterial PaO₂ (measurable by ABG or pulse oximetry)
• Hypoxia = low tissue oxygen (can occur even with normal PaO₂ if oxygen delivery to tissues is impaired)
• Causes of hypoxaemia: Low inspired O₂ (high altitude — not common in UAE), hypoventilation, diffusion impairment, V/Q mismatch, shunt

Oxygen-haemoglobin Dissociation Curve: The S-shaped curve shows how haemoglobin binds and releases oxygen:

• Left shift (high affinity): Fewer O₂ molecules released to tissues — occurs with alkalosis, hypothermia, hypocapnia, foetal haemoglobin
• Right shift (low affinity): More O₂ released to tissues — occurs with acidosis, hyperthermia, hypercapnia, increased 2,3-DPG
• Clinical relevance: In shock (acidosis, hyperthermia), the curve shifts right, releasing more oxygen to tissues — but in severe shock, oxygen delivery is still impaired

2. Indications for Oxygen Therapy

Supplemental oxygen is indicated when:

• SpO₂ < 94% (or < 88–92% for COPD patients — check ABG if in doubt)
• PaO₂ < 80 mmHg on arterial blood gas
• Signs of respiratory distress: Tachypnoea (>24 breaths/min), tachycardia, use of accessory muscles, nasal flaring, intercostal retractions, cyanosis, altered mental status
• Post-operative patients (routine supplemental O₂ for 24 hours per UAE facility protocols)
• Following cardiac arrest
• During procedural sedation

3. Oxygen Delivery Systems

A. Low-Flow Systems (provide variable FiO₂ based on patient’s breathing pattern)

• Nasal cannula: Simple, well-tolerated; allows eating and speaking. Flow >6 L/min causes nasal mucosa drying and discomfort. Humidification recommended for flows >4 L/min.
• Simple face mask: Covers nose and mouth; 5–8 L/min (never less than 5 L/min as CO₂ rebreathing can occur). Maximum FiO₂ ~60%.

B. High-Flow Systems (deliver more precise FiO₂)

• Venturi mask: Colour-coded adapters indicate exact FiO₂ (blue=24%, white=28%, yellow=35%, red=40%, green=50%). Preferred for COPD patients because it allows precise oxygen titration.
• Non-rebreather mask: Reservoir bag attached; one-way valves prevent rebreathing of exhaled air. Delivers highest FiO₂ of low-flow systems. Used for severe hypoxaemia. Must maintain 10–15 L/min flow to keep bag inflated.

C. High-Flow Nasal Cannula (HFNC) Increasingly used in UAE ICUs for acute hypoxaemic respiratory failure:

• Flow rates: 30–60 L/min
• FiO₂: 21–100% (precise titration)
• Advantages: Better comfort than face masks; provides positive airway pressure; better CO₂ clearance
• Used for: Pneumonia, ARDS, acute heart failure, post-extubation support

4. Pulse Oximetry — Interpretation and Limitations

Normal SpO₂: 95–100%

• 90–94%: Mild hypoxaemia (supplemental O₂ needed)
• <90%: Significant hypoxaemia (medical emergency if acute)

Limitations of Pulse Oximetry:

• Does NOT detect hyperventilation or hypoventilation (need capnography for CO₂)
• Falsely elevated: Carbon monoxide poisoning (co-oximetry needed to detect carboxyhaemoglobin)
• Falsely low: Poor perfusion (hypovolaemia, cold extremities), dark nail polish (remove before reading — very common consideration in UAE), motion artefact, dark skin pigmentation (may read falsely high)
• Always use clinical assessment alongside SpO₂

5. Nursing Observations for Respiratory Patients

Respiratory rate: Count for 60 seconds; note pattern and depth

• Tachypnoea (>20/min) — early sign of respiratory distress
• Bradypnoea (<12/min) — may indicate respiratory centre depression (opioids, head injury)

Work of breathing:

• Use of accessory muscles (sternocleidomastoid, scalene)
• Nasal flaring (especially in children)
• Intercostal, supraclavicular, or subcostal retractions
• Tracheal tugging
• Paradoxical breathing (abdomen moves in on inspiration — sign of diaphragmatic fatigue)

ABG Interpretation Basics:

Finding	pH	PaCO₂	HCO₃⁻
Respiratory acidosis	↓	↑	Normal (acute) or ↑ (chronic compensation)
Respiratory alkalosis	↑	↓	Normal (acute) or ↓ (chronic compensation)
Metabolic acidosis	↓	Normal or ↓	↓
Metabolic alkalosis	↑	Normal or ↑	↑

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🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

6. COPD — UAE Context and Management

COPD is one of the top three causes of death in the UAE, driven by:

• High smoking rates (including shisha — a single shisha session delivers as much smoke as 100 cigarettes)
• Outdoor air pollution and desert dust storms
• Indoor pollution (traditional cooking with biomass in some communities)

COPD Exacerbation Signs:

• Increased dyspnoea
• Increased sputum volume
• Purulent sputum
• Chest tightness
• Wheezing

Nursing Management in COPD Exacerbation:

• Oxygen therapy: Target SpO₂ 88–92% via Venturi mask
• DONT: Use high-flow oxygen — can cause CO₂ retention and respiratory acidosis
• Bronchodilators: Nebulised salbutamol + ipratropium (du-neb) — very common UAE protocol
• Corticosteroids: IV or oral hydrocortisone/prednisolone
• Antibiotics if sputum is purulent (common organisms: Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis)
• Non-invasive ventilation (NIV/BiPAP) if CO₂ retaining or fatigued
• IPAP 10–15 cmH₂O; EPAP 5 cmH₂O; monitor for improvement

Home Oxygen Therapy: Some UAE patients require long-term oxygen therapy (LTOT). Criteria:

• PaO₂ ≤ 55 mmHg (or ≤ 60 with cor pulmonale)
• Must be used >15 hours/day for benefit
• Never smoke on home oxygen (fire/explosion risk)

7. Asthma — Acute Management

Asthma prevalence in UAE children is among the highest globally (~15%). Adult asthma is also common.

Acute Asthma Signs (status asthmaticus indicators):

• Silent chest (no wheeze — severe airflow obstruction)
• Cyanosis
• Drowsy/confused (impending respiratory failure)
• Unable to complete sentences
• HR > 110 (adult)
• SpO₂ < 92%
• PEFR < 50% of personal best

Acute Asthma Management (per UAE MOHAP/DOH protocol):

1. O₂ to maintain SpO₂ ≥ 94%
2. Salbutamol nebuliser (5 mg) — can repeat every 20 minutes × 3 doses initially
3. Ipratropium bromide nebuliser (0.5 mg) — combined with salbutamol
4. Systemic corticosteroids: IV methylprednisolone or oral prednisolone
5. Consider magnesium sulphate IV (in severe cases)
6. If no response → ICU; consider intubation

8. Suctioning and Airway Management

Oropharyngeal suctioning:

• For unconscious patients or those unable to clear secretions
• Maximum suction pressure: 150 mmHg (200 mmHg for thick secretions)
• Duration: Maximum 10–15 seconds per suction attempt
• Pre-oxygenate before suctioning
• Do not suction while catheter is being introduced — only on withdrawal

Nasopharyngeal/nasotracheal suctioning:

• Requires physician order
• Measure catheter length: nose to tragus plus 2–3 cm
• Maximum 10–15 seconds; pre-oxygenate
• May trigger bradycardia/vagal response — monitor heart rate

Exam Watch: A patient with a tracheostomy who develops respiratory distress requires immediate assessment: Check the tracheostomy tube for obstruction (secretions, displacement), inner cannula (if present), and external connections. Always suction before attempting any other intervention. In a complete tracheostomy obstruction emergency, attempt to deflate the cuff, remove the inner cannula, and suction — if still obstructed, remove the entire tracheostomy tube and use the stoma opening directly.

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