# Oxygen Delivery Devices

> Nursing notes on oxygen delivery devices for nursing exams: nasal cannula, masks, non-rebreather and Venturi FiO2 ranges, flow rates and safety.

- Canonical URL: https://prepelephant.com/topics/allied/nursing/oxygen-delivery-devices
- Exam / course: Allied Health · Subject: Nursing
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Oxygen Delivery Devices", PrepElephant, https://prepelephant.com/topics/allied/nursing/oxygen-delivery-devices

## Direct answer

Oxygen delivery devices are classified as low-flow (variable FiO2 that depends on the patient's breathing) and high-flow or fixed-performance (precise FiO2). A nasal cannula at 1–6 L/min delivers roughly 24–44 per cent oxygen, a simple face mask at 5–8 L/min about 40–60 per cent, a non-rebreathing mask at 10–15 L/min up to about 90 per cent, and a Venturi mask delivers precise low concentrations of about 24–50 per cent. The choice follows the target saturation, not the device's maximum.

## What you must remember

- Nasal cannula: 1–6 L/min, about 24–44 per cent FiO2 (each litre adds roughly 4 per cent); comfortable for long-term use, but dries the mucosa, so humidification is advised above about 4 L/min.
- Simple face mask: 5–8 L/min (never below 5, or exhaled carbon dioxide is rebreathed), about 40–60 per cent FiO2 for short-term moderate hypoxaemia.
- Non-rebreathing mask: 10–15 L/min with a reservoir bag and one-way valves, the highest concentration among masks; keep the reservoir two-thirds inflated.
- Venturi (air-entrainment) mask: fixed, precise FiO2 set by colour-coded adapters — the choice when exact concentration matters, especially in carbon dioxide retainers.
- Non-invasive ventilation (CPAP, BiPAP) and high-flow nasal cannula are advanced systems for selected patients, not ordinary masks.
- In COPD patients at risk of hypercapnia, titrate oxygen to a target saturation of about 88–92 per cent; in most acutely ill adults the target is 94–98 per cent.
- Nursing care: check flow rate, tubing and mask fit each shift; give skin care at the ears and nasal bridge; change cannulas and humidifier water per policy; display "no smoking" signage because oxygen supports combustion.

## Common confusion

Percentages get swapped in examinations, so remember the logic: the cannula entrains the most room air and gives the least oxygen, while the non-rebreather with its reservoir gives the most. Students also confuse the Venturi mask's role — chosen for accuracy, not high concentration, its classic indication being the COPD patient needing controlled oxygen. A practical trap is the simple mask run below 5 L/min: the FiO2 does not simply fall; the patient rebreathes carbon dioxide from the mask dead space.

## Exam-focused takeaway

Learn the flow ranges and approximate FiO2 for each device, the 88–92 per cent target in COPD, and the rule of never withholding oxygen from a dangerously hypoxaemic patient while awaiting a prescription. Safety questions test humidification thresholds, fire precautions and skin care under masks. A typical stem describes a drowsy COPD patient on a high-flow device with rising carbon dioxide and expects a switch to controlled delivery with a Venturi mask.

## Frequently asked questions

### Which oxygen device delivers the most precise FiO2?

The Venturi or air-entrainment mask, which mixes oxygen with entrained room air through colour-coded adapters to give fixed concentrations.

### What flow and concentration suit a nasal cannula?

1–6 L/min delivering approximately 24–44 per cent oxygen, with humidification usually advised above 4 L/min.

### Why must a simple face mask run at least 5 L/min?

At lower flows the patient rebreathes exhaled carbon dioxide retained in the mask dead space.

### What oxygen target is used in COPD patients?

About 88–92 per cent saturation, since higher concentrations may worsen carbon dioxide retention — but never leave a dangerously hypoxaemic patient without oxygen.

### What safety precautions accompany oxygen therapy?

No smoking or open flames nearby, no oil-based products near the device, secure cylinder handling, and regular checks of flow, tubing and skin under masks.