Makindo Medical Notes

🌬️ Introduction

Oxygen therapy is a cornerstone in managing hypoxemia and respiratory compromise. It supports tissue oxygenation, reduces the work of breathing, and prevents hypoxia-related organ injury. Correct device selection and titration are essential for safe and effective use.

⚠️ Hypoxia can be life-threatening. Oxygen delivery depends not just on flow rate but also the device type, patient’s respiratory rate, and tidal volume. Fixed performance devices (e.g. Venturi masks) deliver more predictable FiO₂ than variable devices.

📌 Indications for Oxygen Therapy

• Hypoxemia of any cause
• Acute myocardial infarction
• Severe trauma
• Post-anesthesia recovery
• Acute severe asthma
• Pulmonary edema
• Acute respiratory distress syndrome (ARDS)
• Pneumothorax (to accelerate air reabsorption)
• Hypoxic sickle cell crisis
• Cluster headaches
• Carbon monoxide poisoning

⚠️ Precautions & Complications

• CO₂ retainers (e.g. COPD): excessive oxygen may suppress hypoxic drive → target 88–92% SpO₂
• Absorption atelectasis with FiO₂ >60% for prolonged periods
• Oxygen toxicity with FiO₂ >50% for >24–48h
• Premature infants: risk of retinopathy of prematurity (ROP)
• Fire hazard in oxygen-rich environments

💡 Types of Oxygen Delivery Devices

• 👃 Nasal Cannula: 1–6 L/min → FiO₂ 24–44%. Mild hypoxemia, comfortable, permits speech/eating.
• 😷 Simple Face Mask (Hudson): 5–10 L/min → FiO₂ 40–60%. Moderate hypoxemia. Avoid <5 L/min to prevent CO₂ rebreathing.
• 🎨 Venturi Mask: Precise FiO₂ 24–60% (color-coded valves). Essential for COPD patients at risk of CO₂ retention.
• 🫁 Non-Rebreather Mask: 10–15 L/min → FiO₂ 60–90%. Severe hypoxemia or emergencies. Bag must remain inflated.
• 🌬️ High-Flow Nasal Cannula (HFNC): Up to 60 L/min, humidified, adjustable FiO₂ up to 100%. Reduces dead space, improves comfort.
• ✋ Bag-Valve Mask (BVM): With O₂ → ~100% FiO₂. Used in respiratory arrest or peri-arrest scenarios.
• 🫀 CPAP: Continuous positive pressure. Indications: acute pulmonary edema, Type I respiratory failure, OSA.
• 🔄 BiPAP: Two pressures (IPAP/EPAP). Indications: COPD exacerbation (Type II RF), neuromuscular weakness, OSA.

🎯 Target Saturations

• Most acutely ill: 94–98%
• Risk of CO₂ retention (e.g. COPD): 88–92%
• Always titrate O₂ to avoid hyperoxia as well as hypoxia.

📊 Summary Table

Device	Flow (L/min)	FiO₂ (%)	Clinical Use
Room Air	–	21%	Stable patients without hypoxemia
Nasal Cannula	1–6	24–44%	Mild hypoxia, long-term O₂
Simple Mask	5–10	40–60%	Moderate hypoxia, short-term
Venturi Mask	Variable	24–60%	Precise FiO₂, COPD patients
Non-Rebreather	10–15	60–90%	Severe hypoxia, emergencies
HFNC	Up to 60	Up to 100%	Severe distress, bridge to CPAP
BVM	15	~100%	Respiratory arrest
CPAP / BiPAP	Variable	Variable	Type I / II RF, OSA, pulmonary edema

🎨 Venturi Mask Color Coding

Color	Flow (L/min)	FiO₂ (%)
Blue	2–4	24%
White	4–6	28%
Yellow	8–10	35%
Red	10–12	40%
Green	12–15	60%

✅ Key Points

• O₂ is a drug: prescribe with target SpO₂ range.
• Use controlled delivery in COPD and CO₂ retainers.
• Monitor with pulse oximetry and clinical exam.
• Document device, flow rate, target sats, and patient response.

📚 References

• BTS Guideline for Oxygen Use in Adults (2022)
• NICE Guideline: Oxygen therapy
• WHO Oxygen Therapy Manual