Monday, November 28, 2005

Questions we answered for Scuba Diving Magazine

I'm planning a trip to the Dominican Republic in a few months. My doctor told me I need to take a prescription antimalarial drug. I've done some research, but I don't know which drug to use. What do you suggest?

Orlando, Fla.

There is no risk for malaria if you're staying in a resort area in the Dominican Republic, but if you'll be visiting rural areas (or taking a side trip to Haiti), you'll need to take an antimalarial drug. Chloroquine (brand name Aralen) or hydroxychloroquine sulfate (brand name Plaquenil) are the drugs of choice for visitors to the D.R.

Malaria symptoms occur at least seven to nine days after a victim is bitten by an infected mosquito. Fever during the first week of travel in a malaria-risk area is unlikely to be malaria; however, any fever should be promptly evaluated.

Travelers who become ill with a fever or flu-like illness while traveling in a malaria-risk area and up to one year after returning home should seek prompt medical attention and should tell the physician their travel history.

Antimalarial Drugs: Know When To Take Them

Drugs to prevent malaria are available only by prescription through a health care provider. Your health care provider should prescribe your antimalarial based on your travel itinerary and medical history. Here's why: Some antimalarial drugs are more effective in some parts of the world than others. In addition, a medical condition may prevent you from taking certain drugs.

Drug - Mefloquine (brand name Lariam)

Dosage - 250 mg (one tablet) once a week—take the first dose one week before arrival, then once a week on the same day while in the malaria-risk area and once a week for four weeks after leaving. Take after eating.

Side Effects - Nausea, dizziness, difficulty sleeping and vivid dreams. Rarely reported to cause serious side effects, such as seizures, hallucinations and severe anxiety.

Recommended For Travel To - South America; Darien and San Blas provinces, including the San Blas Islands, in Panama; Africa; the Indian subcontinent; Asia and the South Pacific.

Drug - Doxycycline

Dosage - 100 mg once a day—take the first dose one or two days before arrival, then once a day at the same time each day while in the malaria-risk area and once a day for four weeks after leaving.

Side Effects - Increased risk of sunburn, vaginal yeast infection and nausea. Can cause permanent teeth staining in children under the age of eight. Do not take if pregnant.

Recommended For Travel To - South America; Darien and San Blas provinces, including the San Blas Islands, in Panama; Africa; the Indian subcontinent; Asia and the South Pacific.

Antimalarial Drugs: Know When To Take Them (cont.)

Drug - Malarone (combination of atovaquone and proguanil)

Dosage - One tablet (250 mg atovaquone/100 mg proguanil) once a day—take the first dose one to two days before arrival, then once a day while in the malaria-risk area and once a day for seven days after leaving. Take at the same time each day with food or milk.

Side Effects - Side effects are rare, but abdominal pain, nausea, vomiting and headache can occur. Women who are pregnant or breastfeeding should not take Malarone.

Recommended For Travel To - South America; Darien and San Blas provinces, including the San Blas Islands, in Panama; Africa; the Indian subcontinent; Asia and the South Pacific.

Drug - Chloroquine (brand name Aralen)

Dosage - 500 mg chloroquine phosphate—take the first dose one week before arriving, then once a week on the same day while in the malaria-risk area and once a week for four weeks after leaving. Take after eating.

Side Effects - Side effects are rare, but nausea, vomiting, headache, dizziness, blurred vision and itching can occur.

Recommended For Travel To - Haiti; Dominican Republic; certain countries in Central America (Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama's Bocas del Toro province); the Middle East and Eastern Europe.

Drug - Hydroxychloroquine sulfate (brand name Plaquenil)

Dosage - 400 mg—take the first dose one week before arrival, then once a week on the same day while in the malaria-risk area and once a week for four weeks after leaving. Take after eating.

Side Effects - Side effects are rare, but nausea, vomiting, headache, dizziness, blurred vision and itching can occur.

Recommended For Travel To - Mexico, Haiti, Dominican Republic, certain countries in Central America, the Middle East and Eastern Europe.

Dive Med Essentials: The Mefloquine Controversy

The most commonly prescribed prophylactic for malaria is mefloquine, or Lariam. While all antimalarial drugs have some side effects, Mefloquine has been linked to disturbing side effects, including anxiety, dizziness, nausea and hallucinations. There have also been a few reports of seizures, frank psychosis and depression resulting in suicide attempts in people taking this medication. That this drug has effects on the central nervous system is not disputed; in fact, the manufacturer recommends that it not be used by anyone with a history of psychiatric illness or seizures.

While these severe side effects are seen almost exclusively in patients taking doses of 1,500 mg, the incidence of side effects such as dizziness, anxiety and nausea seen in patients taking the 250 mg weekly prophylactic dose is also of concern, particularly to divers. Divers should also be aware that some of these side effects mimic the symptoms of decompression illness.

With documented side effects such as confusion, anxiety and seizures, the dangers of diving while on this medication are obvious. Any effects felt on the surface might be exacerbated by the effects of increased nitrogen and oxygen partial pressures.

It should be noted that certain forms of malaria—particularly P. falciparum—have developed resistance to various antimalarial drugs. Because of this, if you are traveling to an area with this type of malaria, you'll have to take mefloquine—the disease is far worse than the side effects.

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Loss of Hearing and Diving

I have read that hearing loss is very common among divers. Is this a sacrifice that I should be prepared to make to enjoy my new addiction?

Paso Robles, Calif.

This depends to a certain degree on how much difficulty you have in clearing your eustachian tubes as you descend and ascend. Difficulty in clearing can cause middle and inner ear damage and hearing loss. This does not always occur, however, and most hearing loss is in commercial divers who are subjected to noise and the changes that take place with clearing difficulties.

Learning to clear is a must for any kind of diving due to the effects of Boyle's Law on the ear. Clearing techniques must be learned or the diver is headed for deafness, ringing in the ear (tinnitus) or dizziness.


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After diving, I often get minor to severe headaches. What's causing this?

Mt. Pleasant, S.C.

There are many different types of headaches, and you'll need to visit a doctor familiar with diving for a thorough examination to determine whether yours are related to diving.

Most diving headaches are caused by either carbon dioxide retention or sinus barotrauma. Here are the most common headaches resulting from diving and what you can do to prevent them.

Carbon Dioxide Headaches

Symptoms: Post-dive localized throbbing pain

The carbon dioxide headache, one of the most common for divers, is caused by an increase in the body's carbon dioxide level, which stimulates receptors in the brain's blood vessels. An increase in the brain's blood flow to these receptors leads to headaches. Typically, they are caused by a diver taking shallow sips of air, which allows carbon dioxide to accumulate. This buildup can also occur when a diver "skip breathes" by pausing after each inhalation and holding the throat closed. Taking measured, slow, complete breaths under water is the best way to avoid carbon dioxide headaches, which don't respond to analgesics or migraine medications.

Tension Headaches

Symptoms: Post-dive neck and head pain

New divers often experience tension headaches resulting from the stress of their first experiences in the underwater world. Clenched jaws and muscular stress in the neck and back of the head lead to these types of headaches, which usually disappear once the diver gains experience and becomes more relaxed under water.

Migraine Headaches

Symptoms: Severe headaches with nausea

Post-dive vomiting can be caused by a migraine headache, but, if coupled with other symptoms, could indicate a DCS headache. If the diver has a history of migraine headaches, then there could be a direct correlation between diving and the onset of the cranial pressure. Unless they are able to take measures to prevent a migraine attack, people with migraines should not dive. If the diver has migraines accompanied by visual anomalies, he should be checked for patent foramen ovale, which may be a factor in undeserved DCS hits.

DCS Headaches

Symptoms: Post-dive headache with neurological deficit

A headache that comes on strong after a dive, coupled with other symptoms like nausea, vomiting, joint pain, dizziness, ringing in the ears, muscle aches, localized swelling, itching or skin rash, could indicate the onset of Type II decompression illness or an arterial gas embolism. This, the most severe dive-related headache, requires a quick response from onboard personnel and a call to the Divers Alert Network to coordinate hyperbaric treatment.

Sinus Headaches

Symptoms: Forehead, face and eye pain during ascent or descent

A diver without a history of migraines could be suffering from a sinus headache, especially if he has a history of problems equalizing. Shifting pressure based on changes in depth without proper equalization can lead to sinus barotrauma. This pain usually spreads across the forehead and eyes. Thus, inflammation of the sinuses, caused by colds or allergies, can further complicate diving.

Post-dive Fatigue

Why am I always tired after diving? My divemaster mentioned something called post-dive fatigue. Can you help?

Crown Point, Ind.

Fatigue in divers often accompanies more acute signs and symptoms of decompression sickness. For other divers, fatigue is the only complaint. Some experts consider post-dive fatigue to be a subclinical form of DCS, possibly caused by tiny bubbles that form in the veins and then filtered out by the lungs.

Fatigue lessens when divers are recompressed, indicating that it may be caused by gas bubbles. On the other hand, anyone who spends the better part of a day out in the tropical sun and breathing compressed air under water is likely to get worn out. If you don't usually lead a fit, active lifestyle, you may just be tired.

Diving After Back Surgery

I had surgery on one of the discs in my lower back to relieve chronic sciatica. Although my back has responded well to the treatment, I am unsure when it would be wise to think about diving again. I have heard that surgery could increase my chances of getting DCS.

London, England

Post-surgical and healed vertebral fusions generally do not prevent divers from pursuing their favorite sport. There is a theoretical increased risk of bubble formation in regions of bone and adjacent spinal cord where there has been some disruption of blood supply. There have been no studies to prove or disprove this possibility, however.

Conventional recommendations about diving after any injury to the spinal cord are that there might be an increased risk of bubble formation at the site of the disturbed blood supply. To my knowledge, there is no evidence to this effect. However, you should consider the risk of an increased incidence of spinal decompression illness and that this risk may be reduced by limiting depth and frequency of dives, using slow ascents and making a safety stop before surfacing.

If you dive, you may have to make adjustments because of the weight-bearing, climbing and hyperextended neck position that is required with scuba diving. You might want to don and doff your gear in the water to avoid excessive weight-bearing, for instance.

There should, however, be no ill effects caused by depth and pressure on the disc herniation. Once your surgeon has cleared you for diving, after you've healed and rehabilitation has occurred, you should be able to dive again (usually six to eight weeks post-op).

It's wise to have a neurological examination carefully recorded to take with you on your dives for comparison reference in case of a decompression accident.

Old and Wiser Diver

I am 68-year-old diver in good physical health. I run 20 miles a week and am presently training for a half-marathon. I got certified in 1995 and have 125 dives in total. Is there a strategy that will allow me to reduce my DCS risk while diving?

Ontario, Canada

You are to be congratulated on keeping yourself in good physical condition. Some people believe that you should gradually reduce the depth and times of dives as you grow older; others feel that you should lengthen safety stops and surface intervals. The only proven ways to reduce your risk of DCS are using nitrox on air tables and not diving at all.

Aging imposes some added risks to divers, but most older divers alter their activities to take these factors into consideration. These include arthritis, heart problems, diabetes and obesity, hardening of the blood vessels in the brain, visual problems and the ever-present specter of cancer. The risk of DCS is thought to increase with age and Carl Edmonds in Diving and Subaquatic Medicine suggests that bottom times should be reduced by 10 percent for each decade of life after 30. Heart problems are by far the most serious of the age-related changes, and probably accounts for the largest number of diving deaths. For this reason, it is recommended that divers over the age of 40 undergo regular cardiac exams.