Oxygen is the standard of care for first aid in dive injuries. You do not need to determine if the injured person is experiencing decompression sickness (DCS), arterial gas embolism (AGE), or nonfatal drowning, as oxygen can be beneficial in all these situations.
While it’s easy to determine if you should use oxygen, some people may be confused about how to administer it.
Mask Selection
The correct setup of your oxygen kit is critical for delivering the highest percentage of oxygen possible, but every situation is different. There are multiple options, and many rescuers forget the best setup for each situation.
First, you should determine if the injured person is breathing or not during the airway, breathing, and circulation (ABC) part of your initial assessment.
If the diver is breathing comfortably, decide whether to use the demand valve or the manually triggered ventilator (MTV). Both are used with a CPR mask with its filter insert removed.
If the diver is breathing but has difficulty reaching the necessary pressure to actuate the valve, switch them to a nonrebreather mask, which should be used on the continuous flow port with a starting flow of 10 to 15 liters per minute (lpm). The nonrebreather mask provides a high percentage of oxygen to the injured person, but as the surrounding air is drawn into the gas flow, less oxygen is being delivered. This method also has more waste due to the continuous flow, and the oxygen cylinder will not last as long as with a demand valve or MTV.
If the diver is not breathing, an MTV is the first choice. With this setup, two people can provide oxygen while doing chest compressions and rescue breathing. An MTV has an overpressure failsafe bypass to prevent lung overinflation, but the rescuer should still be cautious and keep the flow going for no more than one second at a time.
Instead of an MTV, the oxygen kit may have a bag valve mask (BVM), which the provider can use with or without supplemental oxygen. With supplemental oxygen, the injured person gets nearly 100% oxygen. Without supplemental oxygen, the BVM can provide only air (21% oxygen). If the BVM does not have a built-in mask, use the CPR mask without the filter insert.
Rescuers must be especially cautious with a BVM as there is no shutoff to stop them from overpressurizing the lungs. Always slowly depress the reservoir and to no more than one-third of the bag’s volume. Supplemental oxygen is added in the same way as you would connect a nonrebreather mask. Ensure there is sufficient flow to return the bag to normal size before administering the next breath.
If an MTV or BVM is unavailable, the rescuer must do mouth-to-mouth resuscitation with a CPR mask and the filter insert in place. Without supplemental oxygen, the oxygen content for the injured person is about 16%, matching the rescuer’s exhalation. You can add supplemental oxygen using the port on the CPR mask, but it will still be much less than when using an MTV or BVM. Mouth-to-mouth resuscitation requires the most energy from the rescuer and is harder to maintain for a long time.
DAN has developed a new Oxygen Mask Selection Guide slate, which is free to DAN members, to assist with remembering all the oxygen-delivery options during an emergency. Keep this slate in your oxygen kit for easy reference.
| Typical Medical Cylinders | Water Capacity | Total Gas Volume | Total Gas Volume | Expected Duration | Expected Duration |
| (liters) | (liters) | (cf) | (minutes @ 10 L/min) | (minutes @ 15 L/min) | |
| M9 (MC) | 1.7 | 255 | 9 | ±23 | ±15 |
| M22 (Jumbo D) | 3.9 | 623 | 22 | ±58 | ±39 |
| M24 (ME) | 4.9 | 680 | 24 | ±66 | ±44 |
| M265 (K) | 46.4 | 7,510 | 265 | ±690 (11hrs 30min) | ±460 (7hrs 40min) |
Cylinder Selection
The proper cylinder quantity and sizes depend on the expected amount of time you will need to provide oxygen to an injured diver. Consider how far you are from emergency care in the worst-case scenario during your normal diving. You need enough oxygen to cover the travel time during an emergency and account for a buddy who may also need it.
The chart shows the expected duration of typical oxygen cylinders using the continuous flow port. These calculations are based on the usable gas in a full cylinder rather than the total volume.
Care of Your Oxygen Kit
Before each dive outing, confirm that all the kit’s contents are present, clean, and assembled and that the cylinder valve is fully open. Ensure the cylinder contains sufficient oxygen for its intended use. Test the unit’s function, and then turn off the cylinder valve and purge the system, but leave the rest assembled. Keep an inspection log sheet that you initial each time you inspect the kit.
After each use, replace single-use items and check all the components’ functionality. Wipe down regulators and all other components with warm, soapy water, and disinfect any reusable components that were in contact with a person. Refill the cylinder, and function test the unit before stowing it for future use.
Training
Proper training in oxygen administration is necessary. A rescuer will not be able to effectively provide oxygen while trying to figure it out under pressure. DAN’s Diving First Aid or Emergency Oxygen for Scuba Diving Injuries courses and others can provide proper training. A course must include assembling and using emergency oxygen and its limitations.
Practice is also important. An oxygen kit has a lot of components to assemble, and if the rescuer hasn’t handled a kit aside from a couple of hours in class, it will be difficult to remember the steps. The rescuer should have regular training to act with the confidence of muscle memory. When you check the contents of your kit, do a skill circuit to assemble all the components in all the configurations.
Your oxygen kit is a critical resource in an emergency and an essential part of the first aid response in a dive incident. It is essential to understand the various components, how to select and use them, and how to ensure that everything is available and fully operational.
© Alert Diver – Q4 2024