SCUBA Medicine

Gary Podolsky MD

Objectives:

1.To introduce Hyperbaric principles and their effect on the human body.

2.Discuss pathophysiology of common Dive Injuries.   

3.To provide a basis for screening potential SCUBA diving candidates.

SCUBA ( S elf C ontained U nderwater B reathing A pparatus) diving is a safe sport enjoyed by millions with a fatality rate less than downhill skiing (estimated at 1 in 95000 dives).

The risks of serious injuries are either from breathing compressed air or by the other environmental factors exists.

Scuba diving requires that the participant be healthy and be able to respond to problems under water. In the same way that an individual should be competent to drive a car, divers should be held to a higher level of competence since problems could endanger not only themselves but also other divers and rescue workers.

When Not to Dive

Absolute conditions are those diseases or injuries where a person should not dive under any circumstances. These may be temporary as some conditions will change but are often permanent. An individual who was previously cleared to dive may acquire a condition temporary or permanent that would disqualify them from diving. It is every divers responsibility to disclose any conditions that may make him or her endangered, as well as anyone attempting to rescue them. Relative contradictions are conditions that may or may not prevent someone from diving, depending on an individual review by a physician who has knowledge in scuba.

Prevention

Proper scuba technique and medical screening may help minimize these hazards. Scuba diving should be learned from a properly organized course, and not in a compressed afternoon.

Panic has also been a major determinant for disaster in diving. Experience and training will help minimize this. Avoid diving partners who are immature, intoxicated or using street drugs. If you don't like your diving partner(s), break up with them before you agree to go in the water, otherwise, stick with them until the dive is over.

Illness

Divers can be affected in many ways by dive related diseases, as well as the mundane types. It is often difficult for even experienced physicians to make a correct diagnosis in an ill diver.

Any illness should be cleared with a dive physician or by checking with the Divers Alert Network (D.A.N). If in doubt, don't dive. No matter how expensive the trip was, remember you always can enjoy a snorkel, which does not have the risk of dysbarism, since you are not breathing compressed air.

Conditions That May Prevent People From Diving

Because of the varied severity of many conditions, this list is deliberately vague and incomplete and persons with specific medical problems should always clear them with a physician knowledgeable in diving.

People generally do diving over 16 years of age, but frequently children wish to dive. Children as young as 12 years may be considered for diving but this should be very carefully thought out.

Cardiac - Any serious cardiac conditions should not dive unless screened by a Cardiologist and are able to perform 13 METS on an exercise treadmill.

Pulmonary - Any asthma or lung disease should be assessed by a Respirologist, chest x-rays, spirometry and possibly exercise challenge may be needed.

Neurological - Patients with alterations in consciousness or uncontrolled seizures should not dive. Prior decompression illness should be carefully reviewed to evaluate if they should ever dive again.

Ear/Nose/Throat - Divers with hearing in 1 ear or prior ear surgery should not dive. Sudden ear or sinus infections should also not dive till conditions improved (there is a risk of accident and they will have a painful dive anyways).

Gastrointestinal - Divers with digestive diseases have had increased incidences of injuries. Diseases should be stabilized before diving is allowed.

Diabetes - Diabetics with poor control or end organ damage are not recommended to dive. Other endocrine problems should be well controlled.

Extreme obesity has had a higher incidence of decompression illness.

Pregnancy - Women who are or many become pregnant (during dive trip) should not dive. The fetus is vulnerable to dive injuries and the hyperbaric chamber as well.

Blood diseases - Severe anemia and sickle cell diseases should not dive.

Orthopedic - People with severe back pain or recent fractures should not dive. Prior aseptic necrosis (a disease seen in commercial divers) should stop diving.

Behavior - Any psychiatric condition that limits an individual's ability to cooperate with others, solve problems, or react to stress should not dive. Divers themselves should screen unknown diving buddies for incompatibilities before the dive begins.

There should be no use of street drugs or alcohol with diving.

Dental - All cavities and closed spaces should be managed prior to diving.

Drugs - People on medications that interfere with thinking, concentration, or cause sedation should not dive.

Any other condition not mentioned above, that may interfere with the thinking or performance, may also limit diving.

Consider not diving if you are unwell. Definitely do not dive with an ear or sinus infection or any type of respiratory wheeze. One of the main concerns about diving injuries is that many divers will minimize their symptoms or deny them. It is important to have a plan if something goes wrong, agree with your diving partner(s), and always follow through.

Panic and not following through with a simple backup plan are frequently cited as a cause of accident and death.

Pre-Diving Planning

In addition to proper certification, divers should be up to date in their vaccinations if travelling, be counselled on malaria and traveller's diarrhea prevention, be knowledgeable in the prevention of parasites (from swimming in infected water), and seafood poisoning. Divers should be knowledgeable in the water conditions where they are diving.

Other Diving Concerns

Divers should all know CPR to initiate treatment for drowning (those who have heart arrest from lack of oxygen) and near drowning (those who experience a lack of oxygen without a cardiac arrest, but whom also need to be watched carefully). Taking a CPR course at the same time as diving certification could be very valuable. Divers should also know the prevention and treatment of hyperthermia and hypothermia, which can both occur in diving. An oxygen provider is also available through D.A.N.

Some Conditions Related To Breathing Pressurized Gas

Nitrogen Narcoses (Rapture of the Deep)

This usually occurs at depths of 30 feet or 40 meters and is similar to feeling intoxicated. This may be hard to recognize in beginners, so they should limit their depths when starting. Symptoms may range from poor judgment, over confidence, inappropriate behavior and even stupor or coma. The treatment is ascension, until symptoms clear.

Central nervous system oxygen toxicity

This occurs when breathing mixed gas combinations (not regular air) at greater depths. Symptoms include; nausea, dizziness, ringing ears, altered vision, and even convulsion. If convulsing at depths, the buddy should either reduce the oxygen partial pressure by switching tanks or by gentle ascension will also decrease the oxygen pressure, but managing an underwater seizure is difficult.

Carbon Dioxide Toxicity

This can happen under heavy exertion, by skip breathing (slow breathing), or equipment failure. Symptoms include shortness of breath, headache, nausea, dizziness, and confusion. Divers may develop rapid breathing, muscle twitches, and unconsciousness. If breathlessness occurs, divers should stop and rest until breathing returns to normal, if not, then ascend.

Figure 12 Hard Dive suit, Odessa Ukraine

Reference: U.S Navy Dive Manual Volume 2 Revised

Lung Overpressure Syndrome

These problems can occur independently or with an air embolism. They all represent that the lung is injured and an embolism should be suspected.

•  Pneumothorax usually is felt as chest pain or shortness of breath and occurs when air enters the space between the lung and chest wall. This problem worsens with time and treatment in a hospital with needle or chest tube decompression is essential.

•  Mediastinal Emphysema is when air becomes trapped in the space between the heart and the lungs, and is felt as chest pain, shortness of breath and faintness. This must also be followed in a hospital.

•  Subcutaneous Emphysema is when escaped air from the lungs is trapped under the skin, usually at the neck. A swelling and crackling is felt at the neck, with a change of voice and difficult swallowing. This is a simple condition and no treatment is required for it alone. Breathing 100% oxygen will help resolve all types of over- pressure problem.

Motion Sickness

This- should be anticipated and medication should be used with caution since they all cause some drowsiness. It is advisable to cancel a dive if sickness is severe. Some will take meclizine 25 mg taken 2 hrs before dive (lasts 6-12h).

Some illnesses require recompression therapy. They can be subtle but should be acted on promptly if suspected.

Decompression Sickness - is the broad term to describe both air gas embolism (AGE) and decompression syndrome (caused by nitrogen bubbles forming in the body).

S igns and symptoms of AGE include - any type of neurological problem, chest pain, personality change, bloody froth, paralysis, convulsions, and death. Symptoms can occur immediately after surfacing. Airplane travel can also precipitate nitrogen bubble formation.

DAN recommends not to fly 12 hours after the last non- stop diver.

The U.S Air Force recommends 24hrs. Longer time is needed if the dive is a complicated one.

Decompression illness symptoms may also include fatigue, itch, pains in muscles or joints, and a blotchy rash. Even muscular symptoms are worrisome since bubbles could soon form in the nervous tissue. Once you suspect Decompression illness the diver may be categorized as Emergent, Urgent, and Timely.

Treatment of Dive Injuries (Emergent, Urgent and Timely)

Emergent cases are obviously very sick. Begin CPR, and arrange evacuation. Check for foreign bodies and place patient on back (if vomiting, turn onto side) 100% oxygen should be supplied.

Isotonic IV fluids without glucose should be given (this corrects dehydration and reduces hemoconcentration) Give 1 litre over 30 minutes then 100-175 cc/hr.

If trained, insert urine catheter to monitor urine output. After stabilization, contact D.A.N for nearest chamber location. Transfer even if the victim is improving. Take a detailed history, and evaluate neurological status. If flying, pressurized aircraft is recommended.

In cerebral arterial gas embolisms , having the head slightly down, theoretically reduces further emboli towards the brain. Some believe that this can also increase cerebral pressure. A compromise is to keep the victim level with the body and tilted to the left side. In Decompression sickness, muscular or other body movements can dislodge venous emboli so patients should not move. Near-drowning victims movements may redistribute fluid causing decreased lung compliance. Patients with coexistent hypothermia should not be jostled as this could precipitate a cardiac arrhythmia a in a chilled heart.

Additional treatments that have some evidence to support them, include giving ASA (chewable baby aspirin may stops platelets accumulate around bubbles and lidocaine (dose is the same as for cardiac patients).

Lidocaine, given in 1 or 2 boluses, acts to increase cerebral blood flow and may prevent leukocyte activation. Corticosteroids like decadron are sometimes also given but there is less evidence of their usefulness.

Urgent - These patients are those with severe pain that has unchanged or become worse over hours. Their neurological status appears normal. They should be placed on 100% oxygen and given oral fluids. Contact DAN and arrange a transfer.

Timely - These patients have vague complaints with abnormal sensations. Phone DAN and go to the nearest medical facility.

Note that any decompressive symptoms are distressing since they represent nitrogen bubbles in parenchymal tissue (skin, muscle, nerve). Skin and muscle can tolerate hypoxia well but nerve (spinal chord and brain) cannot. Even in those divers only complaining of muscular aches, their bodies are supersaturated with nitrogen that is starting to precipitate out. Other critical tissues may be at risk as this process continues.

Many divers present days after their symptoms have started and by that time the over saturation may be over. Symptoms may persist because of past nerve damage so there is then no value in recommending hyperbaric oxygen therapy. If symptoms are evolving, or unclear check with DAN as they will help everyone who calls.

Dive History - This information is very helpful to D.A.N. Find out all dives (dive logs), symptoms (onset and progressive), all first aid measures, description of rashes, and any other medical information.

Other Problems

Sinus Squeeze - occurs as acute pain in sinuses.

Mask Squeeze - painful pressure build-up around mask.

Ear Barotraumas - acute pain in ear. Should not dive till healed. Inner ear disturbance should be treated as a possible urgent referral to D.A.N (it might only be a perilymph problem in the inner ear but it cannot easily be differentiated from AGE or DCI.

Marine animals and envenomations are beyond the scope of this talk but should be treated by experienced people.

Emergency Contacts For Injured Divers Throughout World

References:

•  Dive and Marine Medicine (3 rd Conference. March 2000, sponsored by The Undersea and Hyperbaric Medical Society.

•  Dive and Travel Medical Guide Ed Thalmann, Editor, Revised 1999, published by D.A.N.

•  Divers Alert Network (D.A.N.) is a non-profit organization that gives information and advice to the general public. They support diving research and have a 24-hour emergency phone number (1-919-684-2948) for dive accidents. Members are eligible for very good travel insurance packages while on dive-related vacations.

•  Bore, Alfred A and Davis, Jefferson C. (1990) Pub W.B Saunders. Diving Medicine.

•  Edmonds (1978) Diving and Sub Aquatic Medicine 2 nd Edition.

•  Divers Alert Network. Report on Decompression Illness and Diving Fatalities 2000 Edition .

•  Undersea and Hyperbaric Medical Society Inc. (July 21, 1995) Published meeting . Are Asthmatics Fit to Dive?

•  Rose, S (2001) International Travel Health Guide 12 th Edition

•  Divers Alert Magazine Published by D.A.N.

•  D.A.N Website link: http://www.diversalertnetwork.org/

•  For your convenience we have prepared downloadable pamphlets on Fitness to Dive and Scuba First Aid at www.skylarkmedicalclinic.com