Scuba Diving

Common Diving Destinations

 Common destinations in the tropics and subtropics: Caribbean- Red Sea –Australia - South Pacific- Indian Ocean –

Travelers at risk:

One million Americans embark on diving holidays every year.

Many travelers are exposed to 5 day resort courses with no past experience of diving at home. Many had  not anticipated this form of activity and some are not properly cleared medically for diving. Resort course safety records vary from excellent to poor. In general they have a good safety record.

Archeologist, motion picture production, tunnel workers, marine biologists, are other groups involved in diving.

Role of travel medicine specialist:

• Scuba is safe for the healthy and well trained .
• TM professionals must be able to assess the traveler’s fitness to certify or to permit  diving during an upcoming trip or following a minor illness
• TM  professionals must be able to advise divers about flying safely after diving and evaluate post-diving  medical problems.

Diving problems

Problems related to aquatic environment

• Hazardous Marine life ( see additional outline on this topic)

Pressure ( increase atmospheric pressure) related problems

• Barotrauma
• Air Embolism
• Decompression Illness
• Dysbaric Osteonecrosis
• Hearing loss
• Compression arthralgia

Environmental exposure problems

• Motion Sickness
• Near Drowning
• Hypothermia
• Heat Illness
• Sunburn
• Allergic reactions ( stings)
• Irritant dermatitis
• Infectious Diseases
• Mechanical trauma
• Breathing Gas Toxicity
• Panic reactions

3  Gas Laws governing scuba

Boyle’s law : The volume and pressure of a gas are inversely related at a constant temperature. ( increase in atmospheric pressure leads to decrease in volume of gas).

Dalton’s Law The pressure exerted by each gas in a mixture of gases is the same as the pressure the gas would exert if it alone occupied the same volume.

Henry’s Law The amount of gas dissolved in a fluid is proportional to the pressure of the gas at which it is in equilibrium. The higher the pressure, the more  gas is dissolved in the tissues.

Barotrauma of descent:

Air pressure within a gas filled space ( middle ear- sinus)  normally is in equilibrium with the environment. If this free flow is obstructed ( nasal congestion from a cold) the air will not be able to expand or contract and it will lead to pain and tissue damage known as barotraumas.

Descent  trauma or “squeeze” affect the sinuses and middle ears if the divers cannot equilibrate. This dysbaric phenomenon can occur in :

The external ear canal plugged by cerumen  -

Middle ear from obstruction of Eustachian tubes – sinus squeeze from sinus drainage obstruction 

This type of barotrauma can lead to pain – tympanic membrane rupture – hemorrhage in the middle ear– vertigo- nausea-

Less common are inner ear barotraumas that can lead to injury to the cochlear vestibular apparatus leading to vertigo tinnitus, hearing loss, and possibly disorientation that could lead to a diving accident.

Barosinusitis affects the maxillary and frontal sinuses most often. It leads to pain and bleeding

Miscellaneous types of squeeze include eye or mask squeeze – suit squeeze from trapped air in dry suits-barodontalgia when air is trapped under a faulty dental filling

Treatment :

• Abstinence of pressure exposure
• Decongestants
• Eustachian tube exercises
• Anti-inflammatory ( Prednisone)
• Antihistamines
• Antibiotics ( In case of infections)
• Audiogram

Barotrauma of Ascent:

On ascent the trapped gases will expand if they are permitted to escape ( obstruction of air passages) or if the diver does not exhale properly on ascent.

Barotrauma of Ascent leads to reverse squeeze with pain and damage by expanding air in the middle air-sinuses-inner-air.

Gastrointestinal Barotrauma of ascent is caused by expanding intralunial gas in the bowels. This leads to abdominal fullness, colicky abdominal pains, belching, and even vasovagal syncope .

Pulmonary Barotrauma is the most serious form of dysbarism. On ascent the Air in the lung expands continuously  Expanding gas will cause the alveoli to rupture producing a spectrum of injuries referred to as the pulmonary overpressurization syndrome or burst lung. Signs and symptoms include pneumomediastinum, subcutaneous emphysema, pneumopericardium, pneumothorax, alveolar hemorrhage. This worse complication is air embolism secondary to air leaking into a ruptured pulmonary vein

Air embolism effects most often the brain but the coronary and visceral circulation may also be affected. Symptoms appear dramatically within 10 minutes of ascent and can lead to acute stroke, paralysis, blindness, confusion, headache, syncope.  All patients suspected of air embolism should be placed in an hyperbaric chamber for recompression treatment. Additonal therapy include oxygen, supportive measures.

Nitrogen Narcosis: Nitrogen is a component of compressed air and it has an anesthetic component at elevated atmospheric  pressure. Although variable, it usually appears at 70 to 90 feet  and at 200 feet it becomes so severe that one can do very little work. It is a reversible condition with ascent  and presents similar to alcohol intoxication. It can lead to fatal accident.

Decompression Sickness DCS

During the diving process, nitrogen is released and dissolves  into the tissues. Depending on the dept of the dive  and it’s duration, the amount of dissolved nitrogen will vary. Upon a too rapid ascent the dissolved nitrogen leaves the tissue  but does not have time to re-equilibrate in the blood and therefore  forms bubbles. This is similar to opening a can of carbonated drink ( I like beer myself)  that has been shaken. These bubbles cause a mechanical and biophysiological effect.

The mechanical effect leads to vascular occlusion ( thrombosis)

The biophysiological effects are on the immune system with release of intrinsic clotting agents, increase in vascular permeability and interstitial edema.

The clinical manifestations are mainly neurological and musculoskeletal.

The most common symptoms  are periarticular joint pains- cutaneous rashes, pruritus, lymphatic obstruction (peau d’orange), spinal cord dysfunction, paraplegia, paresthesia, shortness of breath, tachycardia, shock.

Management of DCS

Recompression in an hyperbaric chamber is the primary and essential treatment. Supportive measures such as IV fluids, oxygen, steroids  are also  indicated.

Medical fitness for Diving:

Prospective divers should be cleared medically before they begin scuba diving.

Disqualifying Medical Conditions for Scuba Diving.

Absolute:

• Seizures
• Asthma
• Emphysema
• COPD
• Cystic lung disease
• Spontaneous pneumothorax
• Perforated tympanic membrane
• Prosthetic middle ear struts
• Ischemic heart disease
• Congestive heart disease
• CNS disease
• Psychosis
• Claustrophobia
• Pregnancy

Relative

• Compromised exercise tolerance
• Post myocardial infarction
• Hypertension
• Insulin dependent diabetes
• Orthopedic deformities
• Prior thoracostomy
• Arthritis
• Sciatica
• Obesity
• Migraine Headache
• Allergic Rhinitis

Temporary

• URTI
• Acute Bronchitis
• Acute gastroenteritis
• Recent major soft tissue injury
• Alcohol intoxication
• Decrease Mental alertness

Flying after diving

Flying too soon after diving can lead to port-flight decompression sickness. About 5% of divers have symptoms.

Normal cabin pressure: 4000 to 8000 feet.

These pressures can cause dissolved nitrogen bubbles to come out of solution and form intravascular bubbles. The exact amount of time between the last dive and safe flying still must be established but the following guidelines should be suggested:

1-     Minimum surface time of 12 hours between non – decompression dive and flying in commercial jet.

2-     For those who have done several days of multiple dives and or dives needing decompression should extend the surface time to 24hours.

Special Travel Insurance

Travelers who will be diving during their trip should be counseled that not all travel health insurance cover diving accidents  and that they should confirm adequate coverage. Specialized insurance plans such as the one offered by  DAM ( diving alert network)  cover a wide range of services aimed at the diver.

Paul Assad

Ref:

Travel Advisor by Kenneth Kizer MD

P.A.D.I .Instructor manual