A stable ward patient needs ongoing oxygen. What must be in place?

A prescription with a target saturation range

The patient's own decision alone

A patient collapses and is severely hypoxic with no prescription for oxygen yet. What should you do?

Wait for a prescription before giving any oxygen

Withhold oxygen until a doctor arrives

Give oxygen only if the family agrees

Why must smoking and naked flames be kept away from oxygen in use?

Oxygen supports combustion and increases fire risk

Oxygen is flammable and explodes

Part B4 of 8 Providing and Evaluating Care Chapter 46 of 75

Oxygen Therapy Scenario Questions

NMC CBT oxygen practice: oxygen as a prescribed drug, target saturations, delivery devices, CO2 retainers, and worked scenario answers.

Start reading ← NMC CBT hub ~5 min read

By JobLabs Editorial · UK healthcare reference editorial team

· July 16, 2026 · Updated Jul 17, 2026 · 2 min read

Oxygen feels harmless because it is everywhere, but in medicine it is a drug with a right dose, and giving too much can be as harmful as giving too little. The CBT tests whether you treat it accordingly.

Oxygen is a prescribed drug

Outside emergencies, oxygen is prescribed like any other medicine, with a target saturation range so it can be titrated up or down to keep the patient in range. Treating it as something you can just turn on, or run on a verbal say-so, is not safe practice. The exception is emergencies, and it is an important one.

Target ranges

Two ranges are worth knowing. For most acutely unwell adults, the target is 94 to 98 percent. For people at risk of type 2 respiratory failure, such as some with COPD who retain carbon dioxide, the target is usually lower, 88 to 92 percent. This is because giving too much oxygen to a CO2 retainer can reduce their drive to breathe and push their carbon dioxide up dangerously. Over-oxygenation is a real harm, not just a waste.

Patient group	Target oxygen saturation (SpO2)
Most acutely unwell adults	94–98%
At risk of type 2 respiratory failure (e.g. some COPD / CO2 retainers)	88–92%

The emergency exception

When a patient is critically hypoxic or collapses, you give oxygen immediately and complete the prescription and documentation afterwards. Withholding life-saving oxygen while waiting for a prescription would be the wrong answer. Treat first, record after.

Devices and fire

Different devices suit different needs. Nasal cannulae and simple masks deliver variable low to moderate oxygen. A Venturi mask gives a fixed, controlled percentage, useful for a CO2 retainer. A non-rebreathe mask delivers high-concentration oxygen at high flow for emergencies.

One safety point rounds it off: oxygen does not burn, but it supports combustion, so fires start more easily and burn harder around it. Smoking and naked flames are kept well away from oxygen in use. Next: wound assessment and dressings. Five oxygen scenarios first.

Sources & further reading

Key takeaway from Oxygen Therapy Scenario Questions

Frequently asked questions

What are the usual oxygen target saturations?

For most acutely unwell adults the target is 94 to 98 percent. For people at risk of type 2 respiratory failure, such as some with COPD who retain carbon dioxide, the target is usually 88 to 92 percent to avoid the harm of over-oxygenation.

When can oxygen be given without a prescription?

In an emergency, oxygen is given immediately to a hypoxic or critically unwell patient and the prescription and documentation follow. Outside emergencies, oxygen is prescribed with a target range like any other drug, and adjusted to keep saturations in range.

Why is high-flow oxygen a risk for some COPD patients?

In people who retain carbon dioxide, too much oxygen can reduce their drive to breathe and cause dangerous rises in CO2. That is why a lower target range is set for them and controlled devices are used, rather than routine high-flow oxygen.

Check your understanding

Quick quiz: Oxygen Therapy Scenario Questions

5questions. Click an answer to see the explanation. Your score is saved on this device only.

1
A stable ward patient needs ongoing oxygen. What must be in place?
Oxygen is a drug and, outside emergencies, must be prescribed with a target saturation range so it can be titrated safely. Treating it as not requiring a prescription, or relying on a verbal say-so, does not meet safe practice.
2
What is the usual target oxygen saturation for a patient at risk of type 2 respiratory failure?
People at risk of type 2 respiratory failure, such as some with COPD, usually have a target of 88 to 92 percent, because over-oxygenation can raise their carbon dioxide dangerously. Most other acutely unwell adults target 94 to 98 percent.
3
A patient collapses and is severely hypoxic with no prescription for oxygen yet. What should you do?
In an emergency, oxygen is given immediately to a critically hypoxic patient, and the prescription and documentation follow. Withholding life-saving oxygen while waiting for paperwork would be harmful. The emergency exception exists precisely for this.
4
Which device delivers a fixed, controlled percentage of oxygen, useful for CO2 retainers?
A Venturi mask delivers a fixed, known percentage of oxygen, which is useful when you need controlled delivery, such as for a CO2 retainer. A non-rebreathe mask gives high-concentration oxygen for emergencies, and a nebuliser delivers medication, not a set oxygen percentage.
5
Why must smoking and naked flames be kept away from oxygen in use?
Oxygen itself does not burn, but it supports combustion, making fires start more easily and burn more fiercely. So smoking and naked flames are kept well away from oxygen in use. Saying it explodes or that it has no effect both misunderstand the real fire risk.