What Are Oxygen Therapy and Ventilation Units?

Two patients on the same ward can both be short of oxygen and need completely different equipment. One, in a COPD exacerbation, improves on a Venturi mask delivering a controlled fraction of inspired oxygen. The other is tiring, and no increase in flow will help, because the problem is the work of breathing itself. Oxygen therapy adds oxygen to what the patient breathes; a ventilation unit takes over part of the breathing.

Last updated: October 3, 2026

Oxygen therapy and ventilation units are different purchases

Oxygen therapy delivers concentrated oxygen by mask, nasal cannula or prongs to raise blood oxygen levels, and it is used for hypoxaemia caused by respiratory disease, heart failure or sleep apnoea. A ventilation unit, also called a mechanical ventilator, delivers air into the lungs under positive pressure and supports or replaces the breathing effort itself.

That difference decides which device a facility buys and which alarm it trains staff to answer. Oxygen therapy is non-invasive and lets the patient breathe naturally; ventilation controls the volume, pressure and timing of each breath and exists for patients whose respiratory muscles are failing. Some systems, such as BiPAP machines, sit between the two and deliver both oxygen and ventilatory support.

How oxygen therapy is delivered

Delivery method is chosen by how much oxygen and how much control the patient needs. Continuous flow suits stable patients; pulse-dose delivery releases oxygen only on inhalation, which is more efficient during activity and therefore better for ambulatory use. Saturation is monitored so therapy can be adjusted, because too much oxygen is a complication in its own right.

What a ventilation unit adds

Ventilators are used invasively, through an endotracheal tube, and non-invasively, through a mask. They offer volume-controlled and pressure-controlled modes so support can be matched to the patient’s lung compliance and drive to breathe, and they carry alarms for pressure, volume and disconnection, because those three are the failure modes of positive-pressure support.

Portable ventilators exist for patient transport and home use, while ICU models add the settings required to wean a patient off support. Weaning is where the mode choice becomes a clinical decision rather than a settings preference.

Ventilation modes, and what each is for

When to escalate from oxygen to ventilation

Ventilation is indicated when the patient shows signs of respiratory failure rather than simple hypoxaemia: a PaO2 below 60 mmHg despite a high fraction of inspired oxygen, rapid breathing, or a pH below 7.25 caused by fatigue. Recognising those signs early is what prevents respiratory arrest.

Non-invasive ventilation is usually tried before intubation, and in acute respiratory distress syndrome it is the accepted first step. The decision point is the direction of travel rather than a single number, which is why the ward record matters more than the last blood gas.

Where the oxygen comes from, and what each source costs to run

Oxygen concentrators are the commonest source for chronic therapy. They extract oxygen from room air using pressure swing adsorption and deliver it at 90–95% purity, so their running cost is electricity rather than refills. Where a precise mixture has to be blended, the Sechrist 3500CP-G oxygen blender is an example of the hardware sitting between the gas source and the patient circuit. Portable cylinders deliver 100% oxygen but need refilling, which suits short-term use and emergencies. Liquid oxygen is denser and more practical for ambulatory patients but needs a supply arrangement. Choosing between them is a logistics question first and a clinical one second.

Maintenance, and the checks that keep a unit safe

Daily checks of filters, alarms and tubing catch most problems before they become events; weekly calibration of flow rates and pressure settings keeps delivery within specification; annual servicing by a certified technician covers what the daily checks cannot see. The maintenance log is the artefact that makes all of it auditable.

Home use: what has to be in place

Home oxygen and ventilation are safe when a prescription, training and monitoring are in place. Portable devices reduce hospital dependency and telehealth provides oversight, but fire-safety precautions and correct storage of oxygen cylinders are non-negotiable parts of the setup rather than optional advice.

References

• FDA: Medical Device Databases — Devices@FDA and quarterly registration and listing.
• FDA: Medical Device Recalls and Early Alerts.
• FDA: Remanufacturing of Medical Devices — what separates servicing from remanufacturing, final guidance May 2024.
• FDA: Classify Your Medical Device — risk class and the premarket route.

FAQ

Is being on oxygen the same as being on a ventilator?

No. Oxygen therapy raises the concentration of oxygen the patient breathes in, and the patient still does the breathing. A ventilator delivers positive pressure to support or replace the breathing itself. Some patients need both, and BiPAP machines deliver a form of each.

At what oxygen level does a patient need ventilation?

A PaO2 below 60 mmHg on a high fraction of inspired oxygen is one of the recognised triggers, along with rapid breathing and a pH below 7.25 from fatigue. The trend matters as much as the number, and non-invasive ventilation is normally tried before intubation.

Concentrator or cylinder for home use?

A concentrator suits continuous long-term use because it needs no refills and runs on electricity. A cylinder suits portability, travel and power outages but needs refilling. Electricity access, refill logistics and flow-rate demand decide the answer.

What maintenance does a ventilator need?

Daily checks of filters, alarms and tubing, weekly calibration of flow rates and pressure settings, and annual servicing by a certified technician. Record the results: the log is what demonstrates the device was maintained to the manufacturer’s protocol rather than simply cleaned.

What should be verified on a refurbished ventilator or concentrator?

The model in Devices@FDA, the recall and early-alert status, the calibration and servicing records against the specification the work was performed to, and whether the refurbishment was servicing or remanufacturing. On a concentrator, also ask for the purity test result at the flow rates you will use.

Part of the Ventilation, Oxygen & Anaesthesia guide.