Saturday 6 June 2009

Administering oxygen

Mounting evidence in recent years points to administering emergency oxygen as one of the single most important first aid steps for a diver suspected of suffering from decompression sickness, lung overexpansion injury or near drowning. Medical case histories show repeatedly that prompt oxygen first aid can make a dramatic difference in the patient's immediate condition and in the effectiveness of subsequent treatment. Let's look at emergency oxygen equipment suitable for use by Rescue Divers.

Emergency oxygen equipment falls into three primary categories: non resuscitator demand valve units, continuous flow units, and positive pressure Resuscitator units. Rescue Divers may use the first two; the letter requires special paramedic level training because it can injure a patient if used improperly.

Non resuscitator demand valve units and continuous flow units adequately meet the needs of a dive emergency.

Non resuscitator demand valve units operate much like your scuba regulator. Oxygen flows only when the patient inhales, so it minimizes waste, and with a proper mask it can deliver nearly one hundred percent oxygen. In addition, a rescuer can inhale from a non resuscitator demand valve unit and ventilate a non breathing patient with a high oxygen concentration (the body only consumes a small fraction of the oxygen in each breath), Dive accident first aids calls for delivering the highest oxygen concentration possible for as long as possible, making the non resuscitator demand valve the best choice for Rescue Diver.

Continuous flow units release oxygen continuously, so they're more wasteful than non resuscitator demand valve units. Fixed continuous flow units usually deliver six or 10 litres per minute; adjustable usually deliver up to 25 litres per minute. With the proper flow (15litres per minute recommended) and a non re-breather mask with reservoir bag, continuous flow units can deliver more than 90 percent oxygen, but with low flow rates and/or an improper mask, the concentration may remain below 60 percent.

By using a pocket mask, you can ventilate a non breathing patient with partially oxygenated air using a continuous flow unit (more about pocket masks and rescue breathing later). Most non resuscitator demand valve systems have multifunction regulators that can be used continuous flow so you don’t sacrifice this benefit.

Emergency oxygen comes in differing tank sizes, and internationally, you may encounter different valve configurations, so it’s a good idea to check the local standards when travelling. Ideally, carry a big enough supply to keep a patient on pure oxygen until in the hands of emergency medical care. However, some very remote dive destinations may make this impractical or impossible; carry as much oxygen as you reasonably can. Some oxygen is better than none at all. For general purposes, 637 litres of oxygen (22.5 cubic feet; even imperial system countries usually measure medical oxygen in litres), can be expected to last approximately 40 to 50 minutes, depending upon whether used with a non resuscitator demand valve or continuous flow.

Like your first aid kit, your oxygen equipment needs a case that can withstand the rigors of diving, ideally one in which you can store your equipment set up and ready to go. Most commercially available oxygen systems for divers come equipped with a suitable case. Most airlines won't let you bring a pressurized oxygen tank aboard the plane when you travel.

If you frequent distant destinations that may not have oxygen on site (i.e., remote locations that lack dive resorts) you can also get systems that have everything except the oxygen tank. Instead, you rent the oxygen tank at your destination and bring it to the dive site.

New Rescue Divers often ask about whether it is legal to give patients oxygen in an emergency, and whether it might cause medical complications. These are valid concerns, but within the scope of diving, administering oxygen in an emergency isn't really an issue

In most areas, there are no laws prohibiting buying medical oxygen for emergency use, or administer­ing oxygen in an emergency. Some areas stipulate that the individual be trained in oxygen adminis­tration (PADI Rescue Diver and/or other emer­gency oxygen diver certifications qualify within the scope of dive emergencies). As long as the patient consents, in most countries there's nothing illegal about providing oxygen in a dive emergency (if the patient is unconscious content is implied).

Only a few countries prohibit giving oxygen in an emergency.

It has been thought that giving oxygen can make a few medical conditions worse, but there’s some doubt about this now, nonetheless, these conditions include emphysema and other lung diseases that impair individuals significantly. People suffering from these are not candidates for diving. Healthy individuals can suffer lung irritation if they breathe high oxygen concentration too long, but this takes hours - more than likely you’ll have the patient in professional medical care, or run out of ­emergency oxygen first. According to DAN recommendations and current emergency care protocols, you don’t have to worry about making someone worse by administering oxygen in a dive emergency.