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Facial baroparesis is a reversible paralysis of the facial nerve due to increased pressure in the middle ear while diving.

Mechanisms

The facial nerve is a cranial nerve that controls the muscles of the face. On its way from the muscle to the brain it passes through a channel in the wall of the middle-ear space. Barometric changes in that space normally have little or no effect on the nerve. However, in some people, the facial nerve canal is missing the bony wall that normally separates it from the middle-ear cavity. This “bone dehiscense” leaves the nerve exposed to the middle ear cavity, protected only by a thin membrane. If such a person were to experience overpressurization in their middle ear — equal to or greater than the capillary pressure — circulation to the facial nerve would stop. The facial nerve’s functionality would be impaired and facial muscles may become paralyzed (i.e., facial baroparesis). Fortunately, pressure in the middle ear generally returns to normal soon after the exposure, restoring the circulation to the nerve and re-enabling its normal functionality. Facial baroparesis tends to recur with repeated diving.

Manifestations

Symptoms include numbness, paresthesia, weakness and even paralysis of the face. Decreased sensation and facial droop may be noted, usually on one side of the face.

Facial baroparesis typically occurs soon after surfacing, as it results from a reverse block.

Management

Facial baroparesis is usually discovered postdive. Even when its duration is brief and it resolves spontaneously, the diver should be evaluated by a physician to exclude other possible causes such as stroke, infection, trauma or decompression sickness. In rare instances of protracted facial baroparesis, treatment may be necessary. There is experimental evidence that overpressurization lasting more than 3.5 hours may cause permanent damage. Divers who continue to experience facial numbness and drooping should see a physician as soon as possible (within three hours).

Fitness to Dive

This condition is usually self-limiting, resolving spontaneously within hours. Because it is caused by an anatomical variation, further exposure to diving (or other significant barometric changes such as flying or other ascent to elevation) can cause recurrence of symptoms. Returning to diving may be considered when symptoms have completely resolved and have been determined to be the result of facial nerve baroparesis rather than a stroke.

Prevention

• Learn gentle but effective equalization techniques.
• Do not dive while congested.

Alternobaric vertigo occurs during descent, ascent or immediately after surfacing from a dive and is caused by unequal pressure stimulation in each ear.

Mechanisms of Injury

During an ascent, the air in the middle-ear space expands, relative pressure increases, the Eustachian tubes open passively, and gas escapes through the Eustachian tubes into the nasopharynx. Occasionally a Eustachian tube may obstruct this flow of air. This obstruction causes increased pressure in the middle-ear cavity. If the obstruction is one-sided and the pressure difference is greater than about 2 feet (0.6 meters) of water, vertigo may occur as the pressure increase stimulates the vestibular apparatus. You can usually relieve it by ascending further. The increasing differential pressure in the middle-ear space forces the Eustachian tube to open and vent the excess air. Contributing factors include middle-ear barotrauma during descent, allergies, upper respiratory infections (congestion) and smoking.

Manifestations

The symptoms of alternobaric vertigo may include disorientation, nausea and vomiting. The disorienting effects of vertigo are extremely dangerous while diving. The inability to discern up from down or follow safe ascent procedures and the risks associated with vomiting pose a significant hazard to the diver as well as other divers in the water.

Prevention

• Avoid unequal pressurization of the ear by avoiding tight-fitting wetsuit hoods or earplugs.
• Maintain good ear hygiene.
• Do not dive when congested or unable to equalize.
• Learn and use proper equalization techniques.

Management

Dr. Carl Edmonds offers the following advice about how to manage alternobaric vertigo during a dive:

“If a diver encounters ear pain or vertigo during ascent, they should descend a little to minimize the pressure imbalance and attempt to open the Eustachian tube by holding the nose and swallowing (Toynbee or another equalization maneuver). If successful, this equalizes the middle ear by opening it up to the throat and relieves the distension in the affected middle ear.”

“Occluding the external ear by pressing in the tragus (the small fold of cartilage in front of the ear canal) and suddenly pressing the enclosed water inward may occasionally force open the Eustachian tube. If this fails, then try any of the other techniques of equalization, and attempt a slow ascent.”

Uncomplicated cases resolve quickly within minutes upon surfacing. If symptoms persist, see your primary care physician or an ENT specialist. Do not dive if you have equalization problems. Associated injuries include middle-ear barotrauma and inner-ear barotrauma. Alternobaric vertigo may occur during descent or ascent but is commonly associated with middle-ear barotrauma during ascent (reverse squeeze). Other conditions, such as inner-ear decompression illness or caloric vertigo (when cold water suddenly enters one ear), should be ruled out.

Fitness to Dive

You can return to diving as soon as all symptoms and contributing factors have been resolved.

Overview

Dialysis is the common name for renal replacement therapy. This therapy is indicated when their kidneys suddenly stop working, or when there is a gradual decline in kidney function and people reach an end-stage renal disease (ESRD). Dialysis works through diffusion of solutes and ultrafiltration of blood through a series of semipermeable membranes. The therapy intends to take over the kidneys’ function, maintaining an adequate hydro-electrolyte balance and removing toxins and byproducts of metabolism. It can be a temporary measure while waiting for a kidney transplant or permanent when a transplant is not possible. But this technology cannot completely and effectively replace the kidneys, and patients undergoing dialysis often cope with a series of complications and side effects.

When a diver requires dialysis, they often ask their doctor about whether or not they can continue diving. This is answer is often not satisfactory enough, as diving physiology is often elusive for most doctors.

While each case is its own universe, below are some general concerns and considerations for people undergoing dialysis.

An individual’s medical and physical fitness to dive should always be addressed individually.

If you are currently seeking dialysis treatment, please take the time to share these general concerns and considerations with your doctor to make sure you can both make an informed decision on whether or not it is safe to continue scuba diving.

Overall Medical Fitness

Most people who end up with a stage of renal disease that requires dialysis are usually unable to meet many minimum requirements to mitigate the inherent risks of scuba diving. Patients with chronic kidney disease are usually on a number of medications, some of which may pose risks or contraindications to diving. The candidate should have no additional comorbidities that could increase the chances of a diving injury, or compromise the candidate’s health or safety.

Fluid Management

Patients on dialysis have a very delicate hydro-electrolyte balance. Diving causes some significant fluid shifts that impose a cardiovascular challenge. Under normal circumstances, these changes are usually well managed with a series of cardiovascular, pulmonary and renal responses. Unless you are diving in 100° F waters, immersion inevitably imposes a variable degree of heat loss. In an attempt to maintain our core temperature, the blood vessels in our skin undergo significant vasoconstriction. As a result, the volume of blood that usually flows through our skin is redirected to our core circulation. In addition, the increased hydrostatic pressure also mobilizes the extravascular fluid that normally pools in our lower extremities into central circulation. This fluid shifts from the skin, and lower extremities effectively increase the volume of circulating blood (hypervolemia) by up to 800 ml on an average-sized person. With the circulatory system being forced to deal with an excess of fluid, the cardiovascular system faces a challenge. Under normal circumstances, our body will manage this excess of fluid by increasing urine production, but a patient with chronic kidney disease will likely struggle to compensate via this method effectively. Failure to adequately manage this hypervolemic state could increase the risk of pulmonary edema and/or result in heart failure. Patients who can still produce urine should consider the cost of a forced and dramatically increased glomerular filtration.

Decompression Stress

Decompression stress is known to cause platelet and complement system activation. While this risk could be minimized by significantly limiting the overall exposure (depth, time, dive profile and ascent rates), it should still be considered a potential additional stressor.

Dialysis Access

Although hydrostatic pressure itself may not necessarily affect the dialysis access, consider the risk of any recreational physical activity disrupting the vascular access. Other considerations include a wetsuit being too tight on the access, which compromises flow and increases the risk of clotting. The effort in climbing up the ladder, combined the with the added weight of the water and BCD straps are also disruptors to vascular access. Consider also the risk of infections when exposed to natural unsanitized water.

Gas Narcosis

Elevated levels of byproducts of metabolism can cause a decreased level of alertness. This per se could be risky while diving. When added to the narcotic effect of gases like nitrogen and carbon dioxide, it is probably prudent to assume that the sum of all could have a synergic effect.

Exercise Tolerance

Anemia is commonly associated with renal failure. Hb levels should be normal to ensure the candidate can have adequate exercise tolerance and overall stamina, and normal blood pressure.

Access to Medical Care

Dialysis patients should take into consideration that diving usually takes place in areas where timely access to advanced medical intervention can not always be guaranteed.

By definition, over-the-counter (OTC) medications are the classification of drugs considered safe for consumer use based solely on their labeling. When used as directed, they present a minimum risk and a greater margin of safety than prescription drugs. They are typically used to treat illnesses that can be easily recognized by the user. Additionally, there are about 300,000 OTC medications currently on the market, far outnumbering the 65,000 prescription drugs.

The fact that these drugs are readily available carries with it a sometimes faulty assumption that all OTC medications are entirely safe, whether you’re topside or underwater. All medications are capable of producing side effects.

There is little research on the effects of drugs used in a hyperbaric environment, such as underwater. Diving while using most medications is a matter for you and your doctor to discuss before you dive.

OTC Categories

Three-fifths of the medications purchased in the U.S. are nonprescription over-the-counter medications. The most commonly encountered OTCs — and those of greatest concern for a sport or recreational diver — fall within the following categories:

• Antihistamines
• Decongestants and cough suppressants
• Anti-inflammatory agents
• Analgesics
• Motion sickness medication

Underlying Condition

A diver considering the use of any medication should first consider the underlying need or reason to take the drug. Does it disqualify you from diving, or does it compromise your general safety and that of other divers?

For example, if you need decongestants to equalize your ears and sinuses, you have an increased risk of serious injury from barotrauma. A seasick diver, medicated or not, may experience in-water disorientation, vomiting, loss of buoyancy control, and embolism as a result of breath-holding or violent diaphragm movement.

No drug is completely safe, regardless of the environment. Drugs are chemicals that alter body functions through their therapeutic action. Any medication could have undesirable effects that vary by the individual or with the environment, with sometimes unpredictable results.

Medication Classes

Antihistamines

Antihistamines can provide relief of the symptoms of allergies, colds and motion sickness. The active ingredients include diphenhydramine hydrochloride, triprolidine hydrochloride and chlorpheniramine maleate.

In therapeutic doses, side effects may include dryness of the mouth, nose and throat, visual disturbances, drowsiness, sedation or depression. These factors can, together or separately, can affect the safety of a dive. Antihistamines can also depress the central nervous system (CNS) and impair a diver’s ability to think clearly and react appropriately.

Decongestants

These drugs cause narrowing of the blood vessels, which often gives a temporary improvement of the nasal airways. Common active ingredients include pseudoephedrine hydrochloride and phenylpropanolamine hydrochloride. Decongestants may cause mild CNS stimulation and side effects such as nervousness, excitability, restlessness, dizziness, weakness and a forceful or rapid heartbeat.

Medications that stimulate the central nervous system may have a significant effect on a diver. Divers with diabetes, asthma or cardiovascular disease may need to avoid using these drugs and should consult with a doctor before using them while diving.

Analgesics & Anti-Inflammatory Drugs

These medications can temporarily relieve minor aches and pains. Active ingredients include naproxen sodium and ibuprofen. Heartburn, nausea, abdominal pain, headache, dizziness and drowsiness are possible side effects. If you have heartburn, gastric ulcers, bleeding problems or asthma, your doctor may discourage you from using these medications.

Remember that even though you may be pain-free, the underlying condition is still present. Limitations in range of movement because of the injury, swelling or pain can put you at risk of additional injury. These medications may mask mild pain due to decompression illness, which can cause you to delay seeking treatment.

With analgesics or anti-inflammatory drugs, one of the most significant considerations is potential adverse drug interactions with anticoagulants, insulin and nonsteroidal anti-inflammatories (NSAIDs).

Motion Sickness Medication

Guidelines regularly prohibit the use of these medications before consulting a physician. Recreational divers should use these medications with caution.

These medications may contain meclizine hydrochloride, dimenhydrinate, diphenhydramine hydrochloride and cyclizine. Common side effects are drowsiness and fatigue, which may impair your ability to perform activities requiring mental alertness or physical coordination.

Medication Under Pressure

Any medication that affects the CNS, such as antihistamines, decongestants or motion sickness medications, has the potential to interact with increased partial pressures of nitrogen. The effects of the drug may increase your chance of nitrogen narcosis. Nitrogen may enhance the sedative or stimulant quality of the drug.

Because of the increased intensity of these effects, a new and unexpected reaction may cause a diver to panic. These side effects can vary from diver to diver, and even from day to day for the same diver. It’s impossible to predict who will have a reaction while diving.

Before You Dive

• Many diving medicine doctors will advise that anyone who requires medication to dive should wait until the illness is over before diving rather than diving while using the medication.
• Consult your physician when you are ill. Your doctor may be able to provide you with more effective medication and counsel you on fitness to dive.
• Study all the information about your medication and understand the warnings, precautions and what effects it may have on your body. Starting the medication at least one or two days before diving may help you assess your reaction to the drug.

OTC Medications Reference

Cardiovascular health plays a formidable part in the safety of any dive. Issues like high blood pressure, coronary heart disease, congenital heart disease, smoking and a family history of heart disease can all compromise cardiovascular health.

Both high blood pressure and heart disease have consistently been the most frequently reported chronic health conditions contributing to dive fatalities for many years. In the 2004 DAN Report on Decompression Illness, Diving Fatalities and Project Dive Exploration, more than 14 percent of the fatalities reported had a chronic history of high blood pressure and/or heart disease. Obesity, another factor reported in 55 percent of fatalities, is connected to heart disease and hypertension, with results linking to poor health and poor exercise tolerance. In combination with other contributing factors, poor cardiovascular health can increase the risk of a severe or fatal dive incident.

To decrease their odds of developing a serious health conditions and to keep the cardiovascular system in tip-top shape, divers can abstain from smoking, exercise regularly and eat a balanced diet. When a diver understands their risks, they are better able to make choices that can positively affect their diving and overall health.

Despite preventative measures, however, sometimes medications are needed to treat these conditions. While cardiovascular medications can help a person with a condition, they do influence someone’s ability to dive safety. Below are some common medications that are used to treat conditions like hypertension and high blood pressure, and possible implications in diving.

Beta Blockers

Commonly used to treat hypertension, beta blockers have a big drawback: They can reduce the heart’s capacity for exercise and therefore affect your exercise tolerance. In addition, if medication restricts the heart’s function during exercise, then there is an increased risk of loss of consciousness, which could prove fatal underwater.

Because of this effect on divers, doctors often recommend a stress test. Divers who use beta blockers and who can achieve a strenuous level of exercise without severe fatigue may be cleared for diving. Although diving does not usually represent the maximum workload on the heart, divers taking beta blockers should avoid extreme exercise because their maximum capacity for exercise may be reduced.

ACE Inhibitors

ACE (Angiotension-converting enzyme) inhibitors have less effect on exercise than beta blockers, so doctors prescribe them for people who exercise more often. Although ACE inhibitors seem to have fewer adverse effects on divers, they can produce a cough and airway swelling — both conditions can cause severe problems underwater. Most people can usually tolerate a mild cough on land, but if a cough due to the drug persists, many physicians will change medications.

Calcium Channel Blockers

Calcium channel blockers don’t typically pose problems for divers: they relax the walls of blood vessels, reducing blood flow resistance and thus lowering blood pressure. In some cases, especially in moderate doses, a change in position from sitting or lying down to standing may cause excessively low blood pressure and a subsequent momentary dizziness. This postural blood pressure change may be a cause for concern with divers, but calcium blockers appear to have no other adverse reaction for diving.

Diuretics

Diuretics reduce the amount of excess water and salt in the body, thus lowering the blood pressure. Divers seem to have very little trouble with diuretics, although in very warm environments, they may cause excessive water loss and dehydration. Because dehydration seems to be a contributing factor to the risk of decompression sickness, divers may want to reduce the dosage on the day of diving. Before changing dosages, however, check with your doctor.

Antiarrhythmics

Antiarrhythmics are designed to help maintain a stable heart rhythm. Some antiarrhythmics, when combined with exercise and a loss of potassium, could increase the risk of injuring the heart. Although these medicines normally do not interfere with diving, the dysrhythmia, or abnormal heart rate for which the medication is being taken, may be a contraindication to diving. Through consultation, a cardiologist and a dive medicine physician should evaluate anyone who has an abnormal heart rate and requires medication.

Anticoagulants

A diver who has been prescribed an anticoagulant (e.g., Coumadin® or Warfarin®) should be warned of the potential for bleeding: excessive bleeding can occur from even a seemingly benign ear or sinus barotrauma. There is a potential risk that, if decompression illness (DCI) occurs, it may then cause significant bleeding in the brain or spinal cord

Overall Implications in Diving

Cardiovascular disease can contribute to dive injuries as well as fatalities — both are preventable. With increased information about cardiovascular health and fitness, divers can make better choices and increase the opportunity that every dive will be accident- and injury-free. Read all you can about your medications and consult with your doctor.

Laurie Gowen

Oxygen toxicity happens when our body’s protective systems are affected by increases in oxygen partial pressure. The tissue-protective mechanisms and biochemical reactions of our bodies are tuned to life in an atmosphere containing 21 percent oxygen, or 0.21 atmospheres absolute (ATA) oxygen partial pressure. Exposure limits are given as partial pressure over time. As the partial pressure gets higher, the recommended exposure time gets shorter.

Oxygen toxicity in the lungs (pulmonary oxygen toxicity) is like a bad case of the flu, but it will rarely cause permanent damage. The most common cause of lung oxygen toxicity is very long recompression treatments.

Oxygen toxicity of the brain, commonly referred to as central nervous system (CNS) oxygen toxicity, is more serious. It can occur during diving, and when it does, it can put a diver at serious risk. The following sections are about CNS oxygen toxicity.

Signs and Symptoms

• Flashing lights in front of your eyes
• Tunnel vision
• Loud ringing or roaring in the ears (tinnitus)
• Confusion
• Lethargy
• Nausea and vertigo
• Numbness or tingling
• Muscular twitching (especially lips)
• Grand mal convulsion

Prevention

The safest practice is to pay attention to the partial pressure and the amount of exposure time. To lower your risk of CNS oxygen toxicity, consider the following recommendations.

• The U.S. Navy uses 1.3 ATA as the maximum limit in its closed-circuit rebreathers. Very long exposures, however, may put the diver at risk for some lung toxicity symptoms.
• The National Oceanic and Atmospheric Administration (NOAA) recommends a more conservative 180 minutes at 1.3 ATA for normal exposures and 240 minutes only for exceptional exposures.
• The Professional Association of Diving Instructors (PADI) has proposed a limit of 1.4 ATA for open-circuit nitrox scuba diving. Because open-circuit scuba diving would not expose divers to this level continuously, it should be at least as safe as the Navy limit for continuous exposures.
• Shallow exposure times in the 1.3 to 1.4 ATA range are mainly to avoid lung oxygen toxicity. The likelihood of CNS toxicity at these levels is very low and probably not much different over this range.
• The Navy allows an exercising exposure at 1.7 ATA for up to four hours, but that assumes breathing 100 percent oxygen at 25 feet (7.6 meters) by trained combat swimmers. A depth excursion of only 5 feet (1.5 meters) puts a diver in a range where convulsions have occurred. Divers who tend to retain carbon dioxide during exercise may be at increased risk.
• The NOAA limit for nitrox diving at 1.6 ATA is 45 minutes for normal diving and 120 minutes for exceptional exposure diving.
• Breathing 100 percent oxygen during a decompression stop at 20 feet (6.1 meters) is a common practice. At this depth, the partial pressure will be about 1.6 ATA. Under resting conditions at that depth, the chance of CNS oxygen toxicity should be very low but is not absent.

Oxygen Partial Pressure Ranges

For open-circuit scuba, the “green light” region is any oxygen partial pressure of 1.4 ATA or less (about 82 feet or 25 meters on a 40 percent oxygen mix). If you don’t exceed this level, the other limitations of open-circuit scuba diving will limit your exposure time to lengths where CNS oxygen toxicity is unlikely.

Between 1.4 and 1.6 ATA (99 feet or 30 meters on a 40 percent mix) is the “yellow light” region. The possibility of oxygen toxicity at 1.6 ATA is low, but the margin of error is very slim compared to 1.4 ATA. Individual variation, an unplanned depth excursion that causes an increase in oxygen partial pressure, and the possibility of having to perform strenuous exercise in an emergency raise the possibility of oxygen toxicity to levels where you should exercise caution. Levels of 1.5 to 1.6 ATA should be only for conditions where you are entirely at rest, such as during decompression. The dive team must still prepare for the possibility of an oxygen convulsion at these levels.

Above 1.6 ATA is the “red light” area. Recreational divers should not exceed this level. Even mild exercise may put divers breathing high-density nitrox mixes at increased risk. Open-circuit scuba divers can achieve durations likely to get them into trouble at these levels. Diving using these high partial pressures of oxygen should be for trained professionals who can weigh the risks and benefits and have the necessary training and support structure in place if an oxygen convulsion occurs.

Responding to Oxygen Toxicity

Nonconvulsive Symptoms

Alert your dive buddy and make a controlled ascent to the surface. Inflate your life preserver if necessary. A buddy should watch closely for the progression of symptoms. While you are not at immediate risk of injury from these symptoms, you should change to a breathing gas with a lower oxygen partial pressure as soon as possible.

Underwater Convulsion

• Get behind the convulsing diver. Release their weight belt. If they are wearing a drysuit, leave the weight belt in place to prevent the diver from assuming a face-down position on the surface.
• Leave their mouthpiece in their mouth. If it is not, do not attempt to replace it. If you can, ensure that the mouthpiece is in the surface position.
• Grasp the diver around the chest above the underwater breathing apparatus (UBA) or between the UBA and the body. If you can’t gain control of the victim in this manner, use the best method possible to obtain control. Grasp the UBA waist or neck strap if necessary.
• Make a controlled ascent to the surface, maintaining a slight pressure on the diver’s chest to assist exhalation.
• If you need additional buoyancy, activate the diver’s life preserver. Do not release your weight belt or inflate your life preserver.
• Inflate the victim’s life preserver upon reaching the surface if you haven’t yet.
• Remove the diver’s mouthpiece after surfacing and switch the valve to surface position to prevent the possibility of the rig flooding, which could weigh them down.
• Signal for emergency pick-up.
• Tilt the diver’s head back to open their airway once the convulsion has subsided.
• Ensure they are breathing. A trained provider can initiate mouth-to-mouth breathing if necessary.
• Monitor the diver for signs of other decompression illness and respond appropriately.

Other Considerations

The main goal while the injured diver is in the water is to keep them from drowning. Next is to ensure that the airway is open after the convulsion stops by keeping the neck extended.

Look for foreign bodies in the trachea. A diver can bite off parts of the mouthpiece during a convulsion, which can find their way into the trachea and block the airway. In these cases, the injured diver will begin coughing as they return to consciousness or may try to breathe but not get any air into the lungs. A trained provider should respond to this foreign-body obstruction of the trachea.

Convulsions are rare, but the symptoms noted above do not always warn of an impending convulsion. The convulsion itself is not harmful. The danger is in the diver losing their mouthpiece underwater or banging their head while thrashing, which could result in trauma or drowning.

Additional Recommendations

• Be aware that oxygen toxicity is unpredictable. Divers have experienced convulsions at shallow depths under conditions where most experts would not have expected them to occur.
• Whenever you breathe a gas with an oxygen fraction above 21 percent, oxygen toxicity is a possibility. Ensure you have appropriate training. Always have a buddy visible. Make sure you and your buddy know what to do if oxygen toxicity occurs.
• Using equipment designed to compress high-oxygen mixtures can be hazardous and requires special training.
• What you get in your cylinder may not be what you expect. Make sure you have a method of analyzing the amount of oxygen in the tank independent of the filling station.
• Remember that rebreathers are intricate pieces of life-support gear. They require more care than a standard scuba regulator.
• Consider your risks when using nitrox. When an oxygen convulsion occurs, it’s almost always underwater, which makes responding more complicated and increases the risk of severe injury or death. Experience, good training and thorough knowledge of nitrox diving by everyone involved are essential.
• Remember that CNS oxygen toxicity symptoms are functions of both time and duration. They will not suddenly occur the moment you exceed a partial pressure threshold — it takes time. As the inspired oxygen partial pressure increases, the exposure time decreases.

Ed Thalmann, M.D.

Many divers have experienced a headache after a dive with it eventually clearing and no lasting side effects. But when headaches are a recurring issue for divers, that’s when it becomes concerning. To help alleviate the pain and discomfort associated with constant headaches, it’s important to try and figure out a potential cause.

One way to find the cause of a headache is to run through a checklist of possible causes and eliminate them one by one. While not an exhaustive list, possible sources may include:

• anxiety or tension
• sinus or ear barotrauma
• sinus and ear infections
• the common cold
• saltwater aspiration
• mask squeeze
• temporomandibular joint pain (TMJ)
• dental problems
• gas toxicity (especially high CO₂)
• decompression illness (DCI)
• migraines
• hyperextension of the neck
• cervical spondylosis
• caffeine or other drugs

Five Questions to Ask

The origins of headaches are truly diverse. However, important clues can usually be found in the history taken from someone who develops headaches regularly. These five key questions may provide an answer to the causes of headaches:

1. Have you had previous head or neck problems, injuries or regular headaches, even when not diving?

Divers who develop headaches regularly above water are also very likely to get them underwater. Such headaches, especially if they are associated with symptoms of nausea, vomiting, abnormal sensations, vision, abnormal smell or even paralysis, may be serious and require assessment by a specialist neurologist.Migraine, a relative contraindication to scuba diving, requires expert assessment. Headaches may also result from tension, large caffeine intake and menstrual changes, among other reasons. A bad-fitting mouthpiece can also cause headache: Some regulators are quite heavy in the water and require a constant “bite” to stay in place. Swapping regulators or trying different mouthpieces may spell the end of a continuous string of headaches. In the end, it is always better to own your own equipment once you have found what works for you. Divers with previous neck or upper back problems or injuries are very prone to develop headaches underwater or even as a result of a bumpy boat trip. The underlying bony problems lead to muscle spasms, which in turn cause the headache. A medical specialist such as an orthopedic surgeon should assess these problems. Physiotherapy and muscle strengthening exercises are often of value. Some report improvement after visiting a chiropractor. Back surgery is usually a last resort.

2. What is the position of your tank on your back?

Is the diver constantly avoiding the pillar valve by bending the part of the neck closest to the shoulders downwards, and then having to hyperextend the part closest to the skull to curl around the valve? As odd as this may sound, it is a very common cause of headache in divers. The solution is to ensure that the neck, when extended normally, does not bring the head against the pillar valve by simply adjusting the position of the cylinder as needed.

3. Where is the pain, and what does the pain feel like?

Pain related to neck problems is usually a persisting non-throbbing pain that gradually spreads from the back of the head to the temples. Sinus pain is usually over the forehead or cheekbones or sometimes behind the eyes or on top of the head. Ear pain is mostly quite obvious, but it is always worth asking whether ear equalizing was easy and effective during a dive.

4. What is your surface air consumption?

Many divers boast about low air consumption or try to artificially reduce their air consumption by skip breathing. The truth of the matter is that removing carbon dioxide from the lungs is very analogous to rinsing dye out of a carpet. The bigger the spill (in our comparison, this would be the amount of exercise which produces more carbon dioxide) and the bigger the carpet (in our example, the size of the person’s lungs), the more water you would need to rinse it clean — that is, the more air you will require to wash the carbon dioxide out. Larger lungs require larger breaths and consequently an increase in air consumption. That is why female divers typically have better air consumption than males. The only way to effectively reduce breathing requirements without building up carbon dioxide is to reduce underwater exercise, ensure adequate thermal protection and to relax; take slow deep breaths (better gas exchange — good rinsing) rather than shallow ones. A healthy breathing pattern is the key to solving many headaches.

5. What was the dive profile?

Long or deep dives, rapid ascents, breath-holding and panic ascents followed by headache all raise the suspicion of DCI as a possible cause. Although fortunately uncommon, DCI is a cause that would require immediate treatment. Abnormal symptoms following any exposure to compressed air should always prompt a suspicion of DCI.

Possible Solutions

Some quick-fix solutions that may be useful include:

• Loosen your mask strap to avoid pressure on the nose, forehead or cheekbones. If necessary, change your mask to a more comfortable one.
• Relax during your dives. After all, you are on holiday.
• Take slow deep breaths. These relax you and provide a more efficient way of removing carbon dioxide.
• Relax your neck during dives. Even though it spoils your trim momentarily, rotating the body rather than the head to look at objects underwater may avoid the strain and the discomfort of hyperextending the neck.
• Stay in shape. Exercise reduces the incidence of headaches.
• Avoid caffeine and tobacco with diving.
• Always follow safe diving practices. Spend three to five minutes at a safety stop at 3-5 meters (10-15 fsw) below the surface. It is relaxing (weather and conditions permitting) and allows time to reduce the carbon dioxide built up from finning to the surface.
• Wear adequate thermal protection.
• Go for regular dive medical examinations, at least every two years for those younger than 40, and annually for those older than 40.

Headaches can spoil a dive trip or vacation and detract from the wonderful underwater experience. Fortunately, once the cause has been determined, many headaches are simple to cure. Those who experience frequent, severely incapacitating or chronic headaches may require an intensive evaluation by a physician to determine the underlying problem.

Remember, it is always better to go for a check-up unless the headache is trivial or can be explained.

Frans Cronje, M.D.

Should a pregnant woman scuba dive?

Whether expectant women should dive is a question that affects not only female divers but also their partners, dive buddies and dive professionals. Most divers can recall from their open water training that women are encouraged to stop diving during pregnancy, but few classes go into further detail. What are the risks of diving while pregnant? What is it about scuba diving that is dangerous for a developing fetus? The published literature provides a foundation for the discussion.

As with all research, there are limitations on how much the available studies can tell us. For ethical reasons, experiments with pregnant women are very limited. Most studies conducted with humans are surveys, and surveys have weaknesses, most importantly that they are not as easily controlled as laboratory research and that they can easily be biased. A survey of female divers who had recently given birth included 69 women who had not dived during their pregnancies and 109 women who had. The nondiving women reported no birth defects, while the diving women reported an incidence of 5.5 percent. To provide perspective, the survey author stated that the latter rate was within the normal range for the national population. The small sample size and the likelihood of selection bias in those responding to the survey make the results even more difficult to interpret. While surveys can establish correlations, they cannot confirm causal relationships. In this case, they cannot confirm that diving caused a defect. To obtain such data, scientists rely on more highly controlled animal studies.

Heather E. Held, B.S. and Neal W. Pollock, Ph.D.

Noninvasive plastic surgeries include Botox injections, chemical peels, collagen injections and others. These are outpatient procedures that could be done in a doctor’s office, completed in a short amount of time and do not require extensive recovery times. Someone would elect to do one of these noninvasive procedures for many reasons. However, it’s important that anyone considering any procedure understand what is involved, what the procedure accomplishes and potential risks. For divers, it’s important to know how a noninvasive plastic surgery procedure could impact future diving. Divers may need to practice prolonged wait times between completion of the procedure and the return to diving to ensure proper healing.

This is a summary of several noninvasive plastic surgery procedures. Besides the risks given for each, other potential complications include bleeding, reaction to the anesthetic and/or infection. Patients should follow their doctor’s instructions to minimize these risks.

Blood thinners are the common name of a number of groups of drugs and chemical substances that can prevent or reduce the coagulation of blood. These drugs can be prescribed to treat a number of blood diseases and to prevent some complications derived from normal clotting, but blood thinning can also be an unintended side effect of some drugs. The biggest risk of blood thinners is excessive or uncontrolled bleeding, which, in a diving environment, could turn into a challenging medical emergency.

What is a clot?

Clots form when blood cells known as platelets stick together, and then proteins in the blood bind them together into a solid mass. This solid mass of blood is called a clot, and when the clot forms inside a blood vessel, it is called a thrombus.

Clotting is a normal function that limits and stops bleeding when a blood vessel is injured. However, if a clot grows out of control or starts to travel within the circulatory system, it then poses a danger. Clots may get lodged in a pulmonary artery and cause a pulmonary embolism; in the arteries of the heart and cause a heart attack; or in the vessels of the brain and cause a stroke. All of these events can be life-threatening.

What are anticoagulants used for?

Anticoagulants and antiplatelets are two classes of drugs that reduce the risk of clot formation. These drugs are usually prescribed to reduce the risk of deep vein thrombosis (DVT), pulmonary embolism (PE), heart attack, and stroke. They may also be prescribed for individuals who have been diagnosed with atrial fibrillation or for those who have had heart-valve surgery or who have received a stent, an implanted pacemaker or an implanted defibrillator. Other patients may require these drugs to counteract an inherited disorder (like Factor V Leiden deficiency or thrombophilia) or an acquired hypercoagulable state like deep vein thrombosis (DVT) or pulmonary embolism due to a recent trauma or surgery, cancer, obesity, pregnancy and others.

Antiplatelets and anticoagulants keep blood from clotting as quickly or as effectively as usual by preventing the platelets from adhering to one another and by preventing the clotting proteins from binding together. They can even help to break up clots that have already formed.

• Antiplatelets — Drugs such as aspirin and clopidogrel (also known by the brand name Plavix) work by preventing the platelets from adhering to one another.
• Anticoagulants — Heparin, warfarin (also known by the brand name Coumadin) and other similar drugs inhibit the action of the clotting proteins and thus slow down the chemical reactions that lead to the formation of a clot. There are also several newer anticoagulants, including rivaroxaban (Xarelto), dabigatran (Pradaxa), and apixaban (Eliquis).

The major side effect of all antiplatelets and anticoagulants is excessive bleeding. Those taking such drugs — especially at too high a dosage — may bleed or bruise easily or may experience bleeding that does not stop as quickly as usual.

Implications in Diving

Individuals who take warfarin (Coumadin) are generally advised to avoid any activities that may cause abrasions, bruising or cuts — such as contact sports. They are also urged to exercise caution while brushing their teeth and shaving. Even such trivial injuries as insect bites may cause complications in anyone taking warfarin.

There are additional risks involving warfarin, particular to diving. Most significantly, there is an appreciable chance of serious injury in any diving environment, despite one’s best efforts to mitigate the risk. Cuts and bruises are unavoidable, for example. And for anyone taking warfarin, a decompression injury or difficulty equalizing ear pressure could cause bleeding in the ears or the spinal cord that would otherwise not occur. In addition, both travel and any resulting dietary disruption can interfere with the action of warfarin in dangerous ways. Furthermore, the health-care capabilities in many popular dive destinations may not be up to providing the care that would be required in case of an adverse event. For all these reasons, anyone taking warfarin is generally advised not to dive. Nevertheless, many people who take warfarin are able to dive without major complications. The keys to safe diving while using warfarin are strict adherence to monthly blood tests and regular surveillance by a physician. With good control of blood-thinning, the risk of a bleeding complication is quite low.

Increased Risks in Diving

• Cuts and bruises are common injuries in almost any recreational outdoor activities. Under normal circumstances, these injuries can be effectively and efficiently managed on-site with proper first aid techniques. However, proper first aid bleeding control techniques may be ineffective on someone who is taking anticoagulants. Under these circumstances, minor injuries can easily become a true medical emergency.
• Middle-ear or sinus barotraumas are by far the most common diving injury, accounting for almost 40 percent of the calls received on the DAN Emergency Line. Under normal circumstances, these injuries are self-limited, as normal coagulation stops the internal bleeding. This allowing the injured diver some time to seek professional medical evaluation for assessment and treatment. When a diver is under anticoagulants, bleeding can only be controlled by applying pressure to the wound, which is not possible on internal bleedings. Under these circumstances, ordinary ear, nose and throat (ENT) barotraumas can easily become a true medical emergency.
• Decompression illness (DCI) takes the risk of bleeding to a new dimension. Bubble formation and growth are known to cause microscopic tissue damage, both through mechanical tissue disruption as well as through normal inflammatory processes. Under normal circumstances, coagulation can control these micro bleeding, and recompression therapy can revert bubble growth, wash-out inert gas, and minimize the inflammatory effects of the injury. When a diver is under anticoagulants, the micro bleeding caused by bubbles can reduce the effectiveness of recompression therapy. This is particularly important in severe DCI cases, like when there is spinal cord involvement or an arterial gas embolism.
• Watch your diet. People taking oral anticoagulants derived from coumarins (like warfarin, acenocoumarol, phenprocoumon, atromentin and phenindione) usually have some dietary restrictions, as an excess in vitamin K in the diet can lessen the effectiveness of the anticoagulant. Foods that are rich in vitamin K include leafy greens like kale, spinach, Brussels sprouts, broccoli, asparagus, collards, mustard greens, Swiss chard and green tea. Small amounts of these vitamin-k-rich foods shouldn’t cause a problem, but large amounts or small amounts over several days could alter the desired balance of anticoagulation therapy prescribed. On the other hand, alcohol and drinks like cranberry juice can increase the anticoagulant effect of these drugs.
• Gastrointestinal maladies (traveler’s diarrhea, changes in diet, vomiting, etc.) are important considerations and can also have a negative impact on the delicate balance of homeostasis by altering the bioavailability of the drug, the absorption and availability of vitamin K, or both.