Divers Alert Network (DAN)
Position Open for: Vice President of Medical Services
Divers Alert Network (DAN), a non-profit 501(c)(3) dive safety organization, seeks a physician for the position of Vice President of Medical Services. This position is located at DAN Headquarters in Durham, North Carolina. This opportunity includes extensive diving medical consultation; medical program development; risk assessment; oversight, evaluation and quality assurance; supervision of professional staff and functioning as a member of a multidisciplinary senior management team.
This position is responsible for the operation and activities of the DAN Medical Department; provides medical guidance and oversight for the DAN Medical Emergency Hotline, the DAN Medical Information Services (both phone and electronic communication) and works cooperatively with the DAN Medical Consultant to assure necessary compliance with current best diving medical practices.
Position requires an MD or DO degree. Candidate should have received additional specialized training in Diving and Hyperbaric Medicine by way of a recognized Hyperbaric Fellowship, Military training and/or Board certification.
The ideal candidate for this position will possess a working knowledge of diving in all its forms and applications and how these constituencies interact with and support diving medicine and research. This includes but is not limited to recreational, scientific, public safety, commercial and military applications.
Interested and qualified persons contact: Dan Orr, DAN President/CEO or Jeff Myers, DAN VP/COO
Divers Alert Network
6 West Colony Place
Durham, North Carolina 27705
(919) 684-2948
U N D E R C U R R E N T O N L I N E U P D A T E
F O R N O N - S U B S C R I B E R S
Undercurrent -- Consumer Reporting for
the Scuba Diving Community since 1975
www.undercurrent.org
August 5, 2008
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Australia Says Dive Boat to Blame for Abandoning Divers: In our July issue, divers Allyson Dalton and Richard Neely gave us their account of being adrift for 19 hours on the Great Barrier Reef after their dive boat, the Pacific Star, failed to pick them up (Online Members can read the story at Undercurrent in our "Back Issues" section). OzSail, which operates the Pacific Star, publicly tried to discredit the divers and blame them for disobeying rules. Now the Queensland government is about to release a report stating the mishap was due to operator error. It's expected to recommend charges against OzSail and the boat's dive trip director Kylie Irwin, recently fired by OzSail. Penalties include up to six months' imprisonment, individual fines of $37,500 and a company fine of $187,500.
Great White Shark Cage Diving: Leave from San Diego August 28; Special deal for Undercurrent; Book the Nautilus Explorer's 6 days/5 nights (4 days of diving) Guadalupe Island great white shark cage diving trip and receive a free stateroom upgrade (space available). Undercurrent readers regularly praise captain Mike Lever and the crew of his 116- foot, 16 passenger modern, comfortable, stabilized liveaboard (they even have 40 micro-brews and 50 different labels of wine) that caters to highly experienced divers, photographers and rebreather divers. Prices start at $2380. If you can't make this trip, they go north to Alaska and south to see the mantas of Socorro island other times of the year. www.nautilusexplorer.com or email undercurrent@nautilusexplorer.com for the special deal.
Ten Year Anniversary Special on Online Membership: Ten years ago we launched Undercurrent Online Membership on our then-new website. As an Online Member, you now have complete access to
To mark this occasion, we're offering a special introductory price for Online Membership -- $29.95/year. This is a ~25% discount off the standard price of $38.95/year. To join simply enter your information, and then you can immediately browse through our 10,000+ pages of reliable diving information from serious divers like yourself. This offer is for a limited time only, so join now.
Coral Spawning Coming up in the Florida Keys: The full moon on August 16 is expected to kick off annual coral mass-spawning rituals. Millions of sperm and eggs will be released into the water to unite at the surface. Branching corals like finger and staghorn typically spawn three to five days after the full moon, two hours after sunset. Star and boulder corals spawn six to eight days after, about three hours after sunset. Marine researchers suggest booking with Florida Keys dive operators for night dives August 19 to 24. One dive shop, Atlantis Dive Center (www.captainslate.com) in Key Largo, is predicting spawning times at 11:20 p.m. on August 22 and 23, and has set aside two boats for each dive.
Buy the Best Fish ID Books Around: Wherever you dive, you need good ID books for fish and corals. We've got the best, covering the Caribbean, Indonesia, Fiji, Hawaii, Mexico and other points. Go to Undercurrent and click on "Diving Books and Guides." You'll get the best price Amazon.com has to offer, and our profit will go to save those fish and coral reefs you'll be reading about on your next trip.
Dive Instructor Charged With Homicide: Dive instructors do make mistakes, but rarely do they lead to murder charges. But in this unfortunate case, Allison Rainey Gibson, a former instructor at the University of Alabama, faces charges of criminally negligent homicide involving the death of her 21-year-old student Zachary Moore in April 2007. Moore's father is also filing a civil lawsuit against her. It alleges that Gibson, 44, was in charge of a dive training class at the university but was giving a private lesson to someone not enrolled in the class, while her official students were practicing taking off their gear at the bottom of the 18-foot pool. Moore had trouble on the surface after the drill and died; an autopsy showed the cause as barotrauma. More details about this incident in a forthcoming issue.
Why Divers Are Cuckoo for CoCo View: In this month's free article online, one of our undercover writer reports on "dive camp" at CoCo View in Roatan, and why it's worth frequent repeat visits. One tip: book way ahead as rooms fill up a year in advance. When you become an Undercurrent subscriber, you'll get immediate access to reader reviews of the island's resorts and dive operators in our Instant Reader Reports. There you'll also find hundreds of reader reviews about dive destinations around the world.
Airlines Alert: Check Your Flight: When you're flying low-cost airlines, reconfirm your flight. A subscriber purchased tickets to Turks and Caicos for a July trip, and called before departure and learned that Spirit Airlines had rearranged her family's flights to an earlier one and, they would have to overnight in Atlantic City before flying to Provo, thereby missing a full day of diving. Because Spirit didn't notify her, the family would have arrived at the airport to find their flight had departed, but luckily they were able to make better arrangements. With airlines like American cutting flights to the Caribbean, stay abreast of your schedule if you have travel plans.
A Bad Economy Means Good Jobs for Divers: The faltering housing market and the soaring price of oil mean more jobs for commercial divers, especially around oil rigs. The Underwater Centre in Fort William, Scotland, expects up to 400 new divers to qualify this year for work in places like the North Sea. There, air divers make $900 a day, while those who must live in decompression chambers can get up to $2,000 a day. The International Diving Schools Association (http://www.idsaworldwide.org) has listings for U.S. and international dive training schools.
Protect your SLR camera from housing leaks: Since most housings suspend the camera in the middle of the space on a platform mount, any absorbent material in the housing bottom will capture the water before it reaches the camera. While you can stuff an old sock in your housing, a feminine hygiene pad is more compact and far more absorbent.
For those of you who might have missed our announcement last month: We have launched an exciting, new feature on our website to help serious divers obtain the best, most complete and latest diving information: The Divers' Forum. This forum offers the thousands of Undercurrent readers a means of directly communicating with each other. You can post questions or replies to others' questions on virtually any aspect of diving. Unlike other forums, here you interact only with other Undercurrent subscribers and Online Members -- as knowledgeable, well traveled, and experienced a group of serious divers as you'll find anywhere. . . If you are not a current print subscriber or Online Member, you can become one in just a minute and get immediate access to the Forum and thousands of pages of solid dive info -- see the offer above. Then log in and join in the dialogue at The Divers' Forum.
What's In The August Issue:
Read it online now. In this issue, you'll find out about:
* CoCo View, a dive camp for hardcore fans in Roatan;
* How to avoid mosquitoes -- and malaria -- in Roatan and the other Bay Islands;
* Good dive travel deals, like all-inclusive weeks starting at $660;
* What's going on with The Spirit of Niguini in Papua New Guinea;
* How dive computers are commonly misused;
* How one guy got an electric shock while cave diving;
* Part I of our series on knowing what's really involved when you sign a dive operator's liability waiver;
* How you can self-publish your own dive photography book;
* Why it's a good idea to spend your afterlife underwater;
* Cayman dive operators are protesting a specific safety regulation; and much, much more.
Ben Davison, editor/publisher
Contact Ben
Department of Diving and Hyperbaric Medicine, Prince of Wales Hospital, Sydney, New South Wales, Australia.
Arterial gas embolism may occur as a complication of diving or certain medical procedures. Although relatively rare, the consequences may be disastrous. Recent articles in the critical care literature suggest the non-hyperbaric medical community may not be aware of the role for hyperbaric oxygen therapy in non-diving related gas embolism. This review is part of an Australian appraisal of experience in the management of arterial gas embolism over the last 10 years. We identified all patients referred to Prince of Wales Hospital Department of Diving and Hyperbaric Medicine with a diagnosis of arterial gas embolism from 1996 to 2006. Twenty-six patient records met our selection criteria, eight iatrogenic and 18 diving related. All patients were treated initially with a 280 kPa compression schedule. At discharge six patients were left with residual symptoms. Four were left with minor symptoms that did not significantly impact quality of life. Two remained severely affected with major neurological injury. Both had non-diving-related arterial gas embolism. There was a good outcome in the majority of patients who presented with arterial gas embolism and were treated with compression.
Pathophysiology
Arterial gas embolism is a major cause of death in diving and the initiating cause (pulmonary barotrauma) usually goes undetected. Caused most often by the expansion of respiratory gases during ascent, it also occurs when the breath is held during ascent from a dive, when there is local pulmonary pathology, when there is dynamic airway collapse in the non-cartilaginous airways and if there is low pulmonary compliance, particularly if this is not distributed evenly throughout the lungs. Boyle's law is the physical law controlling the event. Experimental evidence indicates that intratracheal pressures of about 10 kPa (4 fsw or 1.22 m. or ascending from 170 feet or 51.82 m. to 120 feet or 36.58 m.) are all that's needed for it to happen. Distention of the alveoli leads to rupture, alveolar leakage of gas, and extravasation of the gas into the arterial circuit.
Origin of Bubbles
Bubbles in the arterial circulation can arise from basically three sources: venous gas embolism with breach of the pulmonary vascular filter (paradoxic gas embolism), patent foramen ovale (paradoxic gas embolism) and tear of the pulmonary parenchyma with entry of gas into pulmonary venous outflow. Studies show that systemic venous bubbles are trapped in the pulmonary arterial tree and are usually completely eliminated from that site. The lung traps the air and excretes it into alveoli from the arterioles. (RG Presson, J Appl Physiol; 1989;67(5),1898-1902)
The syndrome of paradoxic air embolism (from septal defects) was first described by J. Cohnheim in 1877. (J Cohnheim, ZV Berline, Hirschwald, 1877;1:134). Hagan at the Mayo Clinic reported on 965 normal hearts and showed that more than 25% of patients with a history of cardiac disease have a 'probe patent' foramen ovale at autopsy. (PT Hagan, Mayo Clinic Proc, 1984; 59:17-20.).
The other main mechanism for arterial gas embolism is by way of the pulmonary overpressure syndrome or 'burst lung'. This occurs from baropressure increases as the diver on compressed air ascends with a closed glottis or a free diver takes a breath of compressed air at depth and ascends. Because of Boyle's law, maximal changes in volume occur in the 4 feet (1.22 m.) closest to the surface and the diver sustains a tear in the pulmonary parenchyma with the escape of air into the pulmonary venous outflow. This can result in several outcomes: pneumothorax (collapsed lung), pneumomediastinum (air in the space around the heart), subcutaneous emphysema (bubbles of air in the fatty tissues under the skin) and air into the pulmonary capillaries.
As the diver takes his first breath after surfacing, the extra-alveolar gas enters the torn blood vessels, migrates to the left side of the heart and is distributed systemically as emboli sent to areas determined by buoyancy.
Arterial gas emboli arise from gas bubbles in the pulmonary capillaries => pulmonary veins to the left side of the heart =>possible coronary artery emboli (rare) or internal carotid and vertebro-basilar arteries to thebrain => cerebral artery embolism (blockage) with the clinical picture of a stroke.
The foam or bubbles block arteries of the 30-60 micron caliber and cause distal ischemia, with astrocyte and neuronal swelling. As the bubble passes over the endothelium, there are direct cellular effects (within 1-2 minutes) causing PMN stimulation. The bubble itself has surface effects causing local swelling, downstream coagulopathy with focal hemorrhages. There is immediate increased permeability of the blood-brain barrier, loss of cerebral auto-regulation, rise in CSF and a rise in the systemic blood pressure. A phenomenon called 'no-reflow' occurs with a post-ischemic impairment of microvascular perfusion. This is thought to be the result of FactorVIII interacting with the prostaglandin system and possibly other blood/tissue factors.
Clinical Manifestations
The clinical manifestations of cerebral gas embolism include a sudden onset of unconsciousness associated with a generalized or focal seizure. There is often confusion, vertigo (extreme dizziness) and cardiopulmonary arrest. In a series of 24 USN cases in which the time was known, 9 occurred during ascent in the water, 11 within one minute at the surface and 4 occurred within 3-10 minutes at the surface.
Other clinical manifestations include the sudden onset of hemiplegia (paralysis on one side), focal weakness, focal hypesthesia (loss of feeling), visual field defect (blank areas in vision), blindness, headache and cranial nerve defects (vision, hearing, eye movements, facial muscles and feeling). The operative word here is "sudden"--nearly all of these symptoms can also be caused by neurological decompression sickness. Less common manifestations are chest pain and bloody, frothy sputum.
Management Outline
Recognition *This usually occurs during or immediately after surfacing*
Symptoms Bloody froth from mouth or nose Disorientation Chest pain Paralysis or weakness Dizziness Blurred vision Personality change Focal or generalized convulsions Other neurological abnormalities Hemoptysis (bloody sputum) Signs Bloody froth from nose or mouth Paralysis or weakness Unconsciousness Convulsions Stopped breathing Marbling of the skin Air bubbles in the retinal vessels of the eye Liebermeister's sign (a sharply defined area of pallor in the tongue). Death
Early management
CPR, if required Open airway, prevent aspiration, intubate if trained person available Give O2, remove only to open airway or if convulsions ensue. If conscious, give nonalcoholic liquids Place in horizontal, neutral position Restrain convulsing person loosely and resume O2 as soon as airway is open. Protect from excessive cold, heat, water or fumes. Transport to nearest ER for evaluation and stabilization in preparation for removal to the nearest recompression chamber. Call DAN (919-684-8111) or your own preferred emergency number Air evacuation should be at sea level pressure or as low as possible in unpressurized aircraft Contact hyperbaric chamber, send diver's profile with the diver,and send all diving equipment for examination or have it examined locally. Recompression as soon as possible
Treatment
Oxygen
Cautious hydration
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PFO (Patent foramen ovale) is a persistent opening in the wall of the heart which did not close completely after birth (opening required before birth for transfer of oxygenated blood via the umbilical cord). This opening can cause a shunt of blood from right to left , but more often there is a movement of blood from the left side of the heart (high pressure) to the right side of the heart (low pressure). People with shunts are less likely to develop fainting or low blood pressure with diving than are obstructive valve lesions (such as mitral valve stenosis or aortic stenosis), but are more likely to develop fluid accumulation in the lungs from heart failure and severe shortness of breath from the effects of combined exercise and water immersion. Ordinarily, the left to right shunt will cause no problem; the right to left shunt, if large enough, will cause low arterial O2 tension (hypoxia) and severely limited exercise capacity. In divers there is the risk of paradoxical embolism of gas bubbles (passage of bubbles into the arterial circulation) which occur in just about all divers in the venous circulation during decompression. Blood can flow in both directions with Intra-atrial shunts at various phases of the cardiac cycle and some experts feel that a large atrial septal defect (PFO) is a contra-indication to diving. In addition, a Valsalva maneuver, used by most divers to equalize their ears during descents and ascents, can increase venous atrial pressure to the point that it forces blood containing bubbles across the PFO into the arterial circulation. Thus the usual filtering process of the lungs is by-passed. Dr. Fred Bove, a Temple University cardiologist, did a search of the literature for patent foramen ovale in relation to diving and diving risks. His conclusion of a meta analysis of 1400 injured divers in about 2.5 million divers (DAN, 1991) in whom the risk of DCS is about 0.05% in the diving population, was that the risk ratio for decompression sickness is increased by a factor of about three for individuals with PFO, and is reduced by a factor of about 2 in individuals who do not have a PFO. It would appear that the risk is low and the significance of the small differences is questionable. Echocardiography is the tool of choice in making the diagnosis of PFO. However, it's probably not a good idea to do an echocardiogram on all divers because of the cost/benefit ratio. If you personally are concerned or are having some of the symptoms of decompression illness that are undeserved, then a bubble contrast echocardiogram should be done. Bubble contrast echocardiography appears to be the most sensitive method for detecting a shunt while color flow doppler appeared to be a poor means of detecting the shunt in a transthoracic echo. There have been recent reports of an association between cerebral emboli, migraines with aura and right to left shunts (PFO). Philip Foster et al, in the Journal of the Aerospace Medical Association, has an elegant article "Patent Foramen Ovale and paradoxical Systemic Embolism: A Bibliographic Review" in which is presented in a single document a summary of the original findings and views from authors in this field. It is a comprehensive review of 145 peer-reviewed journal articles related to PFO that is intended to encourage reflection on PFO detection methods and on the possible association between PFO and stroke. The article abstract and related articles can be seen at this address: Patent Foramen Ovale Closure - A button closure (Amplatzer) is performed trans venously without entering the chest. About four weeks after the surgery, another echocardiogram is done to verify that the device is still in position. After two-three weeks there is an overgrowth of endothelial cells covering the device, reducing the risk of infection. After six to eight weeks the connective tissue has completely filled the spaces in the device and it becomes invisible to ultrasound. Return to diving is usually in six weeks (Wilmshurst), given the full recovery to the satisfaction of the cardiologist/surgeon. Others require a longer wait of twelve weeks. |
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