Oxygen FAQ

Up to date, expert answers to frequently asked questions (FAQ) about oxygen supply systems, respiratory care and pulse oximetry written by OCC & collaborators.

Liquid oxygen

Ventilators without a turbine or compressor generally require both high pressure oxygen (green) and high pressure air (yellow) input to function appropriately, and cannot function at all without at least one of these

Ventilators with a turbine or compressor have the ability to entrain room air directly without a compressed air source; and have variable gas inputs depending on the manufacturer, including the ability to have some combination of:

  1. low pressure oxygen (e.g. from a portable concentrator), via common smooth bore oxygen tubing (this may require a reservoir to augment FiO2 and an adapter to connect to the device)
  2. high pressure (55psi/4bar) oxygen (from central pipes or a cylinder)
  3. high pressure air (usually not, as the turbine or compressor provides this)

Liquid oxygen is generally more expensive than PSA due to the cost of equipment procurement, infrastructure to support the management, and distribution. After the initial investment for a very large-scale LMO production and distribution system, however, the cost will be diminished over time. LOX, LMO

FAQ by Assist International

The primary consideration should be to ensure that the oxygen system is dependable and sustainable.  The best main supply source of oxygen to a patient is a direct piped system that connects to the patient bedside from a PSA plant (or oxygen reservoir supplied by a liquid oxygen source). The direct pipe system is highly recommended and preferred. The alternative is to bring cylinders to the bedside. The back-up supply source for a direct pipe system would be a manifold of cylinders and additional spare cylinders to adequately supply the pipe system if the main supply is temporarily not operating.

FAQ by Assist International

High pressure oxygen sources are capable of delivering oxygen at ~50psi/4bar to a device. These include oxygen cylinders (via regulator), oxygen plants via a compressor, liquid oxygen (via vacuum insulated evaporators) and very few portable oxygen concentrators (via additional compressor). High pressure oxygen is required for most ventilators, high flow nasal cannula and non-invasive positive pressure ventilators when taking care of critically ill patients.

Low pressure oxygen sources deliver oxygen at far less than <50psi/4bar. These include oxygen from a low flow flowmeter or a portable oxygen concentrator. Generally, these cannot deliver high enough oxygen concentrations to take care of severely hypoxemic patients.

***Some ventilators (e.g. LTV2200, Zoll 731) can operate with either high pressure or low pressure oxygen input. Other ventilators (e.g. PB560) may only be capable of utilizing a low pressure oxygen input. Of note – when utilizing low pressure oxygen input, some ventilators may not be able to provide high enough concentrations of oxygen to care for critically ill patients. Check manufacturers’ reports for maximum oxygen concentration delivery.

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