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Home > Health & Wellness > Oxygen – Systems, Uses & Protocols

Oxygen – Systems, Uses & Protocols


Oxygen and an oxygen kit is an integral part of a yacht medical kit.  It is requirement in commercial grade MCA Class A & Class B medical kits and recommended for vessels that conduct extended and remoter cruising

Types of Oxygen systems:

  • Cylinders – Various sizes of cylinders are available (2L, 3L, 5L and 10L are the most typical sizes found on yachts with the 2L size being most common). European cylinders are made of steel (white or black & white cylinders) and US are made of aluminum (grey & green cylinders).  The most common and universal fitting is a pin-index connection. Another fitting is a bull-nose connection.
  • Concentrators – An oxygen concentrator provides an unlimited supply of oxygen and are recommended for yachts with a scuba dive program and those that travel remotely.

One standard 2L cylinder of oxygen will only last about 30 minutes when resuscitating a casualty, whereas an oxygen concentrator will provide an unlimited supply of oxygen, by removing nitrogen from the air, and thus providing 95%+ oxygen.

What should be in an o2 kit:

  • A variable controlled regulator with capability to provide 1L to 15L per minute flow rate. This provides a free flow of oxygen option.  A further option is a demand-valve regulator providing oxygen on demand and preferably to be used in relation to a diving-related injury
  • A pulse oximeter
  • 100% & variable flow masks to provide different percentages of oxygen via the mask and nasal cannulas
  • Airway management items such as a resuscitation mask, guedal airways, airway suction device (to remove fluids in the airway)

Maintenance and testing requirements and standards:

Pressure hydrostatic test:

Maritime and Coastguard Agency Guidance Note MGN 374 (M+F) as well as International Maritime Organization MSC/Circ.850 require hydrostatic testing of the cylinders every five years. Although there are some other recent standards such as ISO18119 that would allow to extend the periodicity to 10 years.  This relates to newly manufactured cylinders produced in the last year which have a 10 yr pressure test rating from new.


With respect to refill, the Maritime Labour Convention refers to local regulations, in some of which state“medical oxygen has a limited shelf life of 3 years and should be landed ashore for recharging prior to the expiry date”.

Medical grade oxygen is classed as prescription drug and should generally only be administered under Doctors guidance.  It is therefore a controlled medication that requires a prescription to purchase.

Uses of oxygen:

  • Resuscitation
  • Cardiac problems – chest pain, suspected myocardial infraction
  • Shock (anaphylaxis, sepsis etc)
  • Unconsciousness
  • Cerebrovascular incident (stroke)
  • Hypothermia
  • A major injury with blood loss
  • A trauma injury
  • An illness or medical disorder
  • Lung-related medical conditions – shortness of breath
  • Essential and the only medication for dealing with a free-diving or scuba diving injury

To provide some general guidance for administration:


Device % oxygen Flow rate l/min Use
Nasal cannulae 24 – 30% 1–4 l/min Non-acute, mildly short of oxygen, max flow rate usually 1-2 l/min
Hudson mask 30 – 40% 5 – 10 l/min Emergency use, simple to set up
Venturi mask 24 – 60% 2 – 15 l/min For longer term oxygen, to control saturations closely. Various colours of adaptors provide different percentages of oxygen
Non-rebreather reservoir mask 85 – 90% 15 l/min Used for acutely unwell casualties. Short-term emergency use only.


Aim for oxygen therapy – target oxygen saturation

  • The usual target oxygen percentage saturation is 92 – 98%. However, for some
  • people with pre- existing lung or heart conditions, the target oxygen saturation may
  • be 88 – 92%. These people are unlikely to be employed seafarers, but
  • could still be found at sea as passengers.


Measuring response to oxygen therapy

There are various ways to monitor the response of a casualty to oxygen therapy, but one of the best ways is the use of a pulse oximeter. A pulse oximeter works by shining a red light through the end of a finger, toe, or other part of the body. The red light detects the pulsing blood in the tissue and can then calculate how much of the blood is properly saturated with oxygen. The device will report not only the percentage oxygen saturation, but also usually the pulse rate as well.


There are other ways, which are useful if there is no usable pulse oximeter on the vessel. These involve assessing the casualty directly.


  • How a patient looks – pink, rather than blue or pale
  • Conscious state – the brain requires a reasonable level of oxygen to function properly
  • Pulse rate – this may go up if the casualty is short of oxygen
  • Respiratory rate – this may go up if the casualty is short of oxygen


If a casualty is severely short of oxygen, the respiratory rate or pulse rate may in fact reduce. This is a very serious situation.