Oxygen and Airway Gear in a Ship's Medical Locker

A ship's medical locker carries oxygen and airway equipment according to the scale set for its flag and trading area, not according to the preference of the master or the medical purse. The scale names the cylinders, regulators, masks, self-inflating bags and airways to be held, and it fixes who is responsible for checking them against expiry. The same scale does not train anyone: the ability to give oxygen or to ventilate a casualty depends on certificates held by individual crew, refreshed at intervals set by the flag administration and the company. The detail of what a circuit or a filter is expected to do, and the standards that govern it, is set out in reference material such as the airway and respiratory device guides published for clinical and biomedical readers.

What the medical scale requires, and who checks it

Most flag administrations publish a medical scale in the form of a table. The table is keyed to the vessel's trading area, its distance from a port of refuge, the number of persons on board and, in some cases, the duration of the voyage. A near-coastal vessel and a vessel on unlimited trading do not carry the same stores, and the difference is written into the certificate the ship holds.

For oxygen and airway equipment the scale usually lists, in some form:

• one or more medical oxygen cylinders, with contents stated in litres or in hours of flow at a given rate;
• a pressure regulator with a flowmeter, and a means of delivering oxygen to a spontaneously breathing patient;
• a self-inflating resuscitation bag with masks in adult and, where children may be carried, paediatric sizes;
• oropharyngeal airways in a range of sizes;
• a portable suction unit or a manual aspirator, with catheters;
• a pulse oximeter, where the scale is recent.

The wording matters. A scale that requires "oxygen therapy equipment" is satisfied by a cylinder, a regulator and a mask. A scale that requires "equipment for artificial ventilation" is not. Reading the scale as a list of items rather than as a list of capabilities is a common source of shortfall at inspection.

Responsibility for checking is usually assigned in the ship's safety management system. The master holds overall responsibility, but the practical task falls to the person nominated in the muster list, often the chief officer or the second officer, with the chief engineer or the electrician for anything that needs a pressure test or a battery change. The check is not only a count. Cylinders are weighed or their pressure read, seals and tubing are inspected for cracking, the bag is squeezed to confirm the valve works in both directions, and every item with a date is checked against it. Expired oxygen, perished masks and hardened tubing are replaced, and the replacement is recorded.

A clinician or a biomedical engineer looking at the same equipment ashore would recognise the categories. The ship's locker holds a small, dated subset of that world.

Who aboard is trained to give oxygen or ventilate a casualty?

Training is a certificate matter, and the certificate is held by a person, not by the ship. The minimum for most commercial vessels is the medical care level required by the flag and by the STCW Convention: elementary first aid for all seafarers, medical first aid for officers, and medical care for the person designated to take charge of medical treatment on board. Oxygen administration and bag-valve-mask ventilation are taught within the medical first aid and medical care courses, not as separate qualifications.

The number of trained persons is set by the same logic as the scale. A vessel with a small crew may have one person at medical care level and two or three at medical first aid level. A passenger vessel or a large crew will have more, and the muster list will name them. The person who checks the locker is not always the person who would use it, and the two roles should be written down separately.

How often is that training refreshed?

Refresher intervals come from three directions at once. The flag administration sets a maximum validity for the medical certificates it issues. The company's safety management system sets its own interval, which may be shorter. The training provider issues the certificate with a date on it. Where the three differ, the shortest applies.

In practice, medical first aid and medical care certificates are commonly valid for five years, with some administrations requiring a shorter period or a refresher before revalidation. Elementary first aid is often folded into basic safety training and follows the same five-year cycle. Beyond the certificate, many companies require an annual on-board drill or a tabletop exercise in which the crew locate the oxygen set, assemble the regulator and mask, and confirm the bag inflates. That drill is not a qualification, but it is the point at which most crews discover that a seal has perished or a cylinder has been returned to the wrong rack.

What can be done at sea before professional help arrives

The honest answer is: less than a hospital, and more than nothing. Oxygen and a bag-valve-mask buy time. They do not treat the cause of a casualty's condition, and they do not replace a diagnosis.

Oxygen is given to a breathing casualty through a mask or nasal cannulae at a flow rate set by the training the crew have received. The aim is to keep the blood oxygen saturation in a range the crew have been taught to recognise on a pulse oximeter, not to run the cylinder empty at the highest possible flow. In a casualty who is not breathing adequately, the self-inflating bag is used with a mask and an airway, with the head positioned to keep the airway open, at a rate and volume the crew have practised. Two rescuers working together do this better than one.

What cannot be done at sea is equally important to state. A crew cannot intubate, cannot provide mechanical ventilation over days, cannot run blood gases, and cannot manage a surgical airway beyond what their certificate permits. The decision to divert, to request a helicopter, or to arrange a rendezvous with a vessel carrying a doctor is a master's decision, taken with the medical advice available by radio. The equipment in the locker exists to keep the casualty alive until that decision takes effect.

The limits of the locker

A medical locker is a dated, finite set of items checked by people whose primary job is something else. Its oxygen and airway contents are set by the flag and the trading area, checked on a schedule recorded in the safety management system, and used by crew whose certificates are refreshed on a cycle. The gap between what the scale requires and what the crew can actually do with it is closed by training and by drill, and by nothing else. A locker that passes inspection and a crew that has never assembled the bag in the dark are two different problems, and only one of them appears on a certificate.