Monday, 16 April 2012

Scuba Diving and Emergency Oxygen

Students divers providing Oxygen during diving accident scenario
In 1878, French physiologist Paul Bert showed conclusively in studies with compressed air divers and caisson workers who worked in diving bells that decompression sickness was caused by inert gas bubbles. Bert further demonstrated that these symptoms improved after inhaling surface oxygen. In one of his experiments on animals he noted: “The favorable action of oxygen was . . . evident; after several inhalations (of oxygen) the distressing symptoms disappeared.”

In a later entry, Bert attempted to explain why oxygen worked. “I thought that if the subject were caused to breathe a gas containing no nitrogen — pure oxygen for example — the diffusion would take place much more rapidly and perhaps would even be rapid enough to cause all the gas (nitrogen) to disappear from the blood.”

This is indeed why oxygen is so useful in treating decompression illness. Bert was the first to propose the concept of oxygen recompression therapy, though the actual practice wasn’t implemented until many years later. In the early 1960s the use of oxygen in recompression treatment for diving accidents increased, but with recreational diving in its infancy, oxygen first aid at the scene of an accident was, for the most part, an unheard-of concept.
It wasn’t until 1976, when noted Australian physician and diver Dr. Carl Edmonds recommended 100 percent oxygen while transporting an injured diver, that oxygen began to emerge as the standard of care for diving injuries.

The movement continued to gain momentum. In 1982, Drs. Jefferson Davis and D.H. Elliott, pioneers in the field of diving and hyperbaric medicine, recognized the value of 100 percent oxygen. Its application, they noted, aided “inert gas elimination from tissues and existing bubbles” in cases of suspected decompression sickness while providing oxygen to hypoxic (oxygen-deficient) tissues.

As oxygen therapy grew in use and recognition, the people who administered oxygen found greater efficiency in some types of masks they were using. Diving medicine expert Dr. Eric P. Kindwall, speaking on the emergency treatment of arterial gas embolism in 1984, noted that oxygen is most effective when administered through a tightly fitting or nasal mask. “The object,” he said, “is to denitrogenate the patient by excluding nitrogen from the lungs.” It became apparent that mask selection had a significant impact upon the fraction of inspired oxygen (FIO2). Masks and delivery techniques which limited dilution from ambient air resulted in a higher FIO2 and ultimately better treatment for the injury.

Breathing elevated concentrations of oxygen is beneficial in the treatment of many scuba diving ailments. Oxygen breathing will increase the oxygenation of any hypoxic body tissues and also help to flush out any dissolved nitrogen and nitrogen present in bubbles. To achieve maximum benefit, the concentration of inspired oxygen should be as near to 100 percent as possible. One hundred percent oxygen is used because it does not contain any nitrogen or other inert gases.

All dive operations should have suitable oxygen equipment and an appropriately trained and qualified Oxygen Provider at the dive site. Ideally, all divers should have access to oxygen should it be needed after the dive.

For maximum benefit, oxygen breathing should begin as soon as possible after a diving injury. If only a limited supply of oxygen is available, it should be given in heavy concentrations from the time that the injury is recognized until the supply of oxygen is exhausted.

Enough oxygen should be available for the anticipated transport time between the dive site and an appropriate medical facility. It is important not to stop oxygen breathing too soon because even if the initial symptoms have disappeared with oxygen first aid, they can re-appear later and can worsen substantially. 

Many oxygen devices have been designed to give oxygen to conscious and unconscious victims, however, very little oxygen equipment has been designed specifically for diving injuries. To help maximize the benefits in diving injuries and more easily achieve 100% oxygen, a demand delivery system should be used where possible. A demand system with a tight-sealing oronasal mask can deliver near-100% oxygen to both the conscious and unconscious diver who are breathing slowly and strongly enough to trigger the demand valve effectively.

A breathing diver who cannot use a demand valve can breathe high oxygen concentrations via a non-rebreather mask with a flow rate of around 15 liters per minute (ensuring that the reservoir doesn't empty). A non-breathing diver can be ventilated with relative ease and safety using a resuscitation mask attached to an oxygen outlet with a flow rate of 10 to 15 lpm.

DAN ( Divers Alert Network ) has been instrumental in the development of certain types of oxygen units which are designed to provide a simple, safe and effective means of providing oxygen to injured divers. DAN's 'Oxygen First Aid for Scuba Diving Injuries' course provides divers with the required knowledge and skills to safely administer oxygen to injured divers and is the most highly-regarded course in which to learn these skills. Do not provide Oxygen if you are not trained to!

Oxygen Equipment - Photo copy rights reserved to/ http://www.webscuba.net

Some General Safety Rules when Using Oxygen Equipment:
• Position the injured diver appropriately
• Ensure are is well ventilated and nothing is burning
• Ensure your hands and equipment are free from grease & oils
• Slowly turn the cylinder valve at least one full turn
• Provide oxygen asap to injured diver & at the highest possible concentration
• Record the periods of oxygen breathing and the injured diver's response to it
• Do not cease providing oxygen until advised to do so by a diving physician
• Carefully monitor the diver and oxygen equipment function at all times

Continue providing oxygen until the supply is depleted. Interrupt temporarily if the diver vomits, regurgitates, has a seizure or has difficulty breathing from the equipment. Resume oxygen provision as soon as possible and never leave the injured diver unattended.

Using a Demand Valve
• Ensure the diver is breathing effectively, attach the mask to the demand valve and check its function
• Position the mask ensuring an airtight seal
• Listen for demand valve sounds to ensure proper function and diver's activation
• Reassure a conscious diver and closely monitor the diver and equipment function

Using a Non-Rebreather Mask
• Ensure the diver is breathing effectively
• Set the flow rate to 15 lpm and prime the reservoir bag
• Position the mask and adjust to obtain the best seal possible
• Reassure a conscious diver breathing normally through the mask

Using a Resuscitation Mask with a Non-Rebreathing Diver

• Commence CPR while oxygen equipment is being prepared
• Attach tubing to mask and set flow rate to 15 lpm
• Position the mask and obtain an airtight seal
• Tilt the diver's head back, lift the jaw & continue CPR as required
• Closely monitor the diver and equipment function

It is extremely important that emergency medical services groups be prepared to respond to diving injuries. It is not out of the realm of possibility to be presented with a patient showing symptoms of a diving injury even though there is no known dive sites in the vicinity. Divers commonly drive or fly long distances to and from remote dive locations. Since signs and symptoms may not be apparent for some time after the dive, it is conceivable that an injured diver may enter into the local EMS system literally hundreds or possibly thousands of miles from the nearest known dive site. Therefore, it is incumbent upon all EMS personnel to have some knowledge of diving injuries no matter how remote the possibility/

Therefore, it is always good idea to improve your knowledge, keep diving skills and rescue skills as sharp as it should be. 

References:

DAN ADVANCED OXYGEN FIRST AID FOR SCUBA DIVING INJURIES, DAN, Durham, NC. 2002, 32 pages.

DAN OXYGEN FIRST AID IN DIVE ACCIDENTS INSTRUCTOR TRAINER MANUAL, DAN, Durham, NC. 1993, 72 pages.  

DAN OXYGEN FIRST AID FOR SCUBA DIVING INJURIES, DAN, Durham, NC, 2002, 74 pages.

Compressed Gas Association Teleases Position Statement On Aluminum Regulators, Alert Diver, Juk/Aug. 2000, 16.

NIOSH and FDA Warn of Risk from Aluminum Regulators in High-Pressure Oxygen Systems, Pressure, 28(3), May/June,1999, 1-2, 5-6.  

Flatter , Hazards Of Oxygen Therapy, Am. J. Nursing

Gorman, D. Decompression Sickness And Arterial Gas Embolism In Sports Scuba Divers, Sports Medicine, 8(1), 1989,  32-42.  



No comments:

Post a Comment