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.

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