Decompression Illness – Knowledge is your Best Protection

They say that for every Ying there is a Yang, For every good there is a bad. For scuba diving the bad is Decompression illness, or DCI. To quote the Diver Alert Network (DAN), the largest organization focused on dive medicine,
“DCI encompasses two diseases, decompression sickness (DCS) and arterial gas embolism (AGE). DCS is thought to result from bubbles growing in tissue and causing local damage. While AGE results from bubbles entering the lung circulation, traveling through the arteries and causing tissue damage at a distance by blocking blood flow at the small vessel level.”
While there are similarities between the two, it best to remember DCS relates to tissue and AGE to blood supply.
In the early day of diving, before we learned about the effects of gases under pressure on a divers body, DCI caused many deaths and gave scuba diving the notoriety of being a deadly thrill. It is not really an accurate statement saying the effects were unknown, it is more accurate to say they were not understood, not by medical personnel and clearly not by divers.

Decompression Sickness, What is it and how to avoid it

In your open water training, you review the basic principles of three laws of chemistry, they are Boyle’s, Charles’s and Henry’s laws. Elements of these laws will help to explain how gases under pressure react within our bodies. In 1662, a physicist and chemist named Robert Boyle proved a theory that volume and pressure were inversely proportional. We learned Boyle’s law in science whereas when pressure increases volume decreases. This principal is not only important for us to understand for DCS avoidance but also impacts how long a tank of air will last. Boyle also believed that nitrogen under pressure would be introduced into our blood stream in larger amounts and forced into tissue. Henry’s Law in 1803 proved that Boyle was right. It also showed two important concepts. Increased pressure also increased the solubility of blood to carry nitrogen, and the tissue would try to balance the present of nitrogen in the lungs. Boyle also stated that if the nitrogen was not able to escape the tissue, it could cause physical damage. As we descend the partial pressure of nitrogen we breath goes up, as well at the blood’s ability to carry it. So the tissues start loading nitrogen. When we ascend, the partial pressure is now higher in the tissue, so it will start exciting the tissue. However, the blood solubility for nitrogen has been reduced so there is a delay leaving the tissue. Think of it as a three lane highway going in but just a one lane coming out. If you give it enough time, it will get out. DCS is medically classified into two types, type I which is pain only, and type II which covers the rest.
In the late 1800’s, workers building the Eads Bridge (St. Louis) and the Brooklyn Bridge (New York City) were becoming ill and many of them died from the illness. The bridges were being built using caissons. These are metal devices with an air lock at the top and open at the bottom. They were placed on the river bed and filled with compresses air to pump the water out. The pressure was maintained to keep the water out. Workers would enter the device’s airlock, travel to the bottom to work digging and placing the foundations and anchors for the bridges. When they returned to the surface, many of them became ill within minutes. The illness became known as Caissons Disease, which we now know as Decompression Sickness. DCS can be slow in its appearance. Most cases appear between 5 minutes and six hours after a dive, a small percentage up to 12 hours and even smaller percentage as long as 48 hours. Flying or going to a higher elevation can also bring on DCS if excessive nitrogen remain in your tissue. Divers are advised to wait 24 hours before flying. Symptoms of DCS which the workers also endure are (these are things you feel):

• Unusual fatigue
• Skin itch
• Pain in joints and / or muscles of the arms, legs or torso
• Dizziness, vertigo, ringing in the ears
• Numbness, tingling and paralysis
• Shortness of breath

Signs of DCS (Item that are noticeable):

• Skin may show a blotchy rash
• Paralysis, muscle weakness
• Difficulty urinating
• Confusion, personality changes, bizarre behavior
• Amnesia,
• tremors
• Staggering
• Coughing up bloody, frothy sputum
• Collapse or unconsciousness

It did not take long before all workers suffer to some degree from DCS. It was noticed that the symptoms became milder or disappeared entirely while the worker was deep in the caissons. In the medical studies it was found that if they brought workers up slowly, fewer became ill, even less if they stopped for a few minutes on the way up. These doctors for the bridge building company’s were the first to bring light to the concept that we use for maximum assent rate and the principals of decompression diving. On a light note, the situation with the workers lead to the development of the term bends. In scuba slang we will hear someone say, “they got bent” or “be careful of the bends”. Technically this applies to type I DCS. For the caisson workers, within a few minutes most were bent over in some degree of pain after their work shift ending. At the time there was an upper class fashion called the Grecian Bends. The body position of the men in pain from their work was very similar to the body position of women wearing the Grecian Bends style. So the term was also applied to the workers.
These early studies were expanded upon by the US Navy and the U.S. Navy dive tables were developed. Using a maximum rate of assent as a part of the calculations, the dive tables gave some guidance how long a diver could stay down and avoid DCS. This is the science behind all the dive tables, dive computers and warnings you receive.
In your open water training, you will learn or did learn the principals of avoiding DCS. They include how to read the dive tables and use them to plan your dives. Also, included will be the safe rate of ascent and the practice of a 3 minute stop at 5 meters for extra safety. Currently, the use of the dive tables is not as frequent as it once was after training. Dive tables are based on diving to a specified depth and the calculations are based on that. Technology in the form of dive computers can read current depth and time then use formulas to give a real time evaluation based on your dive. Still, having a good understanding of dive tables are a good foundation to manage your risk.

Unexplained DCS

DCS does have another dark side, even if you follow all the rules, you still can get DCS. It is known that certain factors can increase the risk of DCS. Certain drugs, a hangover, being overweight and dehydration are just some the known factors that might make someone more likely to become a victim. Even setting those factors aside, some people get it anyway. The percentage is small but still there.

Treatment

If you have any concern that you or a fellow diver is being effected by DCI you need to seek medical attention. As an immediate first aid, administer 100% oxygen. This may be enough to slow the progression and maybe even stop it. Then get evaluated by a medical professional knowledgeable of dive medicine. A decompression chamber is used to treat DCI, it brings a patient to a condition under pressure and slowly brings them back to surface conditions. Prompt treatment may result in no lasting complications.

Arterial Gas Embolism (AGE)

The second member of the Decompression illness classification is the Arterial Gas Embolism. AGE happens when bubble in the blood stream blocks the flow of blood, a bubble larger than the capillary vessel. The lack of blood can cause tissue damage. As the brain is one of the largest users of blood, it is the one organ most at risk. AGE can cause strokes and create brain damage. The percent of AGE cases only make up about 7% of the DCI cases. As bad as that sounds there is one thing to remember, AGE is almost 100% preventable. When you breathe, the lungs diffuses gas into the blood stream. Large molecules are blocked. AGE is caused by a Pulmonary Expansion barotrauma. This happens when you hold your breath during ascent. The air in your lungs expand as the gas does. However, when it reaches its limit it will burst, just like adding air to a balloon eventually it will burst. This rupture in the lung will allow air to pass directly into the blood stream without the larger molecules being blocked. In some rare cases AGE has occurred on seemly normal ascents. These cases have mostly been linked to preexisting heart or lung conditions.
Symptoms of AGE

• Dizziness
• Visual blurring
• Areas of decreased sensation
• Chest pain
• Disorientation

Signs of AGE

• Bloody froth from mouth or nose
• Paralysis or weakness
• Convulsions
• Unconsciousness
• Cessation of breathing
• Death

Many of the signs and Symptoms of AGE are similar to DCS type II, and the first aid for them are the same. Administer 100% oxygen, make comfortable and seek medical attention immediately. AGE symptoms appear rapidly and escalate fast. Unlike DCS which seldom has symptoms underwater, death due to AGE can happen before the diver can reach the surface.

Insurance

There is an old joke against the medical field, it says the leading cause of heart attacks after surgery is seeing the hospital bill. The best means to avoid this is to have good medical insurance. Even if you have medical insurance, consider getting dive medical insurance. Dive insurance companies generally have agreements in place with decompression chambers where the chambers will accept the insurance. Most insurance companies do not and if not, you will need to made a deposit before treatment is started. Deposits can range from $5,000 to 25,000 cash. Best to think ahead.

Diving’s Worst Case

When you take your Open Water Diver training, most of the knowledge section and many of the skills relate to DCI and how to avoid it. It is these skills that you will practice and master that makes DCI a managed risk. Forty years ago if you became a certified scuba diver your life insurance company would cancel your policy. Some policies would have a higher premium for divers and exclude any benefits for deaths that happened elated to diving. Times have changed, today diving is considered safer than horseback riding, and you have a greater chance of being injured on a golf course than getting a DCI. This is due to the training and you understanding of the risk.
Continue reading more from the DeeperBlue.com Beginners Guide to Scuba Diving.

How to Improve Your Style, Dive Longer

Have you every watched a shark as it moves along the reef? You see its smooth almost majestic movements, the stream line body, and the relaxed manner it moves into a school of fish. You know that it has power and great speed, however, the shark only calls on it when needed. The shark has evolved to be efficient under the water, scuba divers have not. We have to work at it. The way we move through the water greatly impacts the energy we spend and the air we consume. It is a skill that takes time and conscious effort to learn and sadly many divers do not even try. Often, it is a case that we do not know how bad we really are, it takes someone to tell us or show us.

What is a proper form

The proper form will keep you moving in a stream line manner, much like your favorite shark. Your body from the head to your knees should form a straight line. Your head should be forward facing and you knee bent to a 90° angle. This may sound easy but it does take a little work. When you first start working on your form, do not concern yourself too much that you are not horizontal. The position of your weights will affect the horizontal position. Once you have the form proper or at least close, you can adjust the weight trim.
Most people have poor posture, no matter how many times our mother told us to stand up straight. We will find that our muscles have remembered those positions we normally use. When we float, the body will relax but may not necessarily form the position we need. Many will find their natural position is with the rump up higher than the spine. This forces the legs down, now when we kick we are forcing our selves up as well as forward. The best way to correct this is to arch your back slightly, square your shoulders and stretch your chest. This is the form you will see parachutist take in free fall.
Your knees should be bent so that your calves are slightly above your back and the ankle relaxed allowing the blade of the fins to be parallel with your body. Your hands are not a part of your propulsion underwater. They should be held in a stream line position if they are not in use such as holding a gauge or a light. Many divers will hold the arms in front of them, one hand lightly grasping the other wrist. Arms at your side or folded across your chest are also popular means to stay stream line.
I became certified at a local dive center near where I was living for a year. After becoming certified, many of my dives were with my instructor as the dive master. We would spend our 5 meter safety stop working on my and my dive buddies form. The instructor gently controlling our body positions to help create a muscle memory. That is something you and your buddy can do.

Using weights to adjust your trim

The article on buoyancy control briefly mentioned trim. Your body has a center of gravity (COG), a pivot point if you will. Like a seesaw you want to keep the weight on ether side in balance. The further away from the center of gravity the greater the impact weight will have. While the location of your dive weights are important, it has to be used in conjunction with other items. The cylinder is often overlooked as an element of trim. It’s position can matter a great deal as it is on both sides of your COG. If you find your trim changes between your first and second dive, the location of your tank may be the cause. Most BCD’s have an adjustable loop that fits over the neck of a dive cylinder. You can use that strap as a guide to position your tank each time. When you find the proper position for your tank, tighten the loop. Each time you place your BCD on a cylinder slide the BCD down until the loop is tight before securing the dive band. Many times divers will let the boat crew change over the equipment and they may not be as detail orientated as you should be.
The balance of the cylinder impacts your trim, however, as you start working on your trim its balance is less important than it being consistent. Some BCD’s have shoulder pockets for trim weights, weights added here will reduce a positive trim, one where your chest is higher than the COG. If your BCD does not have a shoulder pocket, you can purchase weights that will clip to your d-rings. Divers can place some weight on the tank or tank band. Weight added near the neck of a tank will bring the chest down and legs up. Weights near the tank boot will have the opposite effect. As you move weights to different locations, remember that you must maintain enough weight on your weight belt or other quick release to gain positive buoyancy in an emergency. You should also account for heavy gear. If you have a large dive light clipped to your BCD, not bringing it on a dive might affect your trim.
Streamlining your equipment is an important point. Like the streamlining you do with your hands, anything outside your body profile will cause drag, that will affect your profile. Keep hoses and gauges close to the body.

What goes up must come down

A article we foundt about using Viagra some guys might find interesting when diving in Thailand
Popular prescription medications for treating erectile dysfunction include Viagra, Cialis, and Levitra. They work by increasing blood flow to certain areas of the penis, and like all meds have side effects. Most worrisome is a potentially dangerous decrease in blood pressure in those taking certain other drugs that also dilate blood vessels. Other possible side effects tend to be transient and mild in nature, but still can be

problematic for the diver. Examples include headache, stomach upset, nasal congestion, and muscle aches.

Taking one of these medications in proximity to diving could impede equalization of the ears and sinuses, or result in heartburn, nausea, and burping, complaints that could be further exacerbated by the prone and sometimes head-down positions assumed while diving. The well-known “blue vision” that is a common side effect of Viagra generally is of little concern to recreational diver safety.

The diver taking one of these drugs will want to monitor for topside adverse reactions before diving. Among other advantages, this may prevent symptoms like headache and muscle ache from being confused with DCI or vice versa.

There is no reason to suspect that these medications increase the likelihood of DCI, and in fact, preliminary research with animals suggests such ED drugs could reduce the probability.

Finally, any limitations or risks to safe scuba imposed by the condition(s) causing the ED (e.g., diabetes, obesity, psychiatric disorder) also must be considered.

This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual and should not be construed as such. Consult with your physician before taking a drug and diving.

Equalizing made easier

Here a article I found't  that might help many divers who have problems equalizing as some time you might have to call the dive off hope you find it useful

   

Ear woes are the No. 1 reason divers pull the plug on a dive, and in extreme cases, the sport itself. But with a few tricks and advanced techniques, almost anyone can make equalizing easier. In diving, the Valsalva maneuver is often used on descent to equalise the pressure in the middle ear to the ambient pressure. Performed properly — pinching your nose shut while exhaling — most divers can descend without any problems. But for some divers, the technique doesn't help.

You should never continue with a descent if you are experiencing ear pain. But before you give up on a dive — or diving itself — try these tips.

Listen for the "pop." Before you even board the boat, make sure that when you swallow you hear a "pop" in both ears. This tells you both eustachian tubes are opening.

Start early. Several hours before the dive, begin gently equalizing your ears every few minutes. Chewing gum seems to help because it makes you swallow often.

Equalize at the surface. "Prepressurizing" at the surface helps most divers get past the critical first few feet of descent. It may also inflate your eustachian tubes so they are slightly bigger. Not all medical authorities recommend this, however. The lesson here is to pre-pressurize only if it seems to help you, and to pressurize gently.

Descend feet first. Studies have shown a Valsalva maneuver requires 50 percent more force when you're in a head-down position than head-up.

Look up. Extending your neck tends to open your eustachian tubes.

Use a descent line. Pulling yourself down an anchor or mooring line helps control your descent rate more accurately. A line also helps you stop your descent quickly if you feel pressure.

Stay ahead. Equalize often, trying to maintain a slight positive pressure in your middle ears. Don't wait until you feel pressure or pain.

Stop if it hurts. Your eustachian tubes are probably locked shut by pressure differential. Ascend a few feet and try equalizing again.

Avoid milk. Some foods, including milk, can increase your mucus production.

Avoid tobacco and alcohol. Both tobacco smoke and alcohol irritate your mucus membranes, promoting more mucus that can block your eustachian tubes.

Keep your mask clear. Water up your nose can irritate your mucus membranes, which then produce more of the stuff that clogs.

Alternative Clearing Techniques

There are  problems with the traditional Valsalva maneuver: It may not work if the tubes are already locked by a pressure differential, and it's all too easy to blow hard enough to damage something. Divers who experience difficulty equalizing may find it helpful to master some alternative techniques. 

Toynbee Maneuver. With your nostrils pinched or blocked against your mask skirt, swallow. Swallowing pulls open your eustachian tubes while the movement of your tongue, with your nose closed, compresses air against them.

Lowry Technique. A combination of Valsalva and Toynbee: while closing your nostrils, blow and swallow at the same time.

Edmonds Technique. While tensing the soft palate and throat muscles and pushing the jaw forward and down, do a Valsalva Maneuver.

Frenzel Maneuver. Close your nostrils, and close the back of your throat as if straining to lift a weight. Then make the sound of the letter "K." This forces the back of your tongue upwards, compressing air against the openings of your eustachian tubes.

Voluntary Tubal Opening. Tense the muscles of the soft palate and the throat while pushing the jaw forward and down as if starting to yawn. These muscles pull the eustachian tubes open. This requires a lot of practice, but some divers can learn to control those muscles and hold their tubes open for continuous equalization.

Photos of this months marine life

Scribbled Filefish this photo was taken at Shark Island just of the coast of Koh Tao.

Cuttlefish this was take at Mango Bay in Koh Tao

Spotted Grouper at Twins

Hexagon Grouper

February 2013

February was a great month with loads of happy divers!

Sail Rock has not been at its best this month, with visibility at only a couple of metres so most of our dives have been to Koh Tao.

Congratulations to Shane, Anna, Eibhlin and Tony who have all passed their Open Water, and to Darryl who passed his Advanced Open Water course.

Steve, Molly and Paul Came out for a great day diving and it was the start of perfect conditions, it was flat and calm the whole way to and from Koh Tao and the visibility was excellent, we even managed to find Molly a turtle at White Rock.

Jack, Andy, Donald and Serefin had a good day at Koh Tao, even if conditions were not quite perfect, our first dive was at Green Rock, where there was a fair bit of current, and then on the second dive to Twins the visibility was not what we are used to! But still we managed to spot all our usual marine life including barracudas, moray eels, porcupine fish…..

Rob booked up to come out for a day and ended up spending 3 days on he boat, he was hoping to get to Sail Rock but unfortunately conditions weren’t improving so he had 3 days at Koh Tao.

We’ve managed to get a couple of good dives at Chumpon Pinnacle this month, which has been great, sadly no whale sharks the days that we’ve been there, but there were lots of barracuda around.

We have had a few days of Discover Scuba Diving this month which everyone thoroughly enjoyed!

A couple of our regulars have been back out with us, Colin and Pam came out…….Paul  got the chance to go and see the wreck, whilst Davie was back and got in a 62 minute dive!

There’s been some amazing marine life around a Banded Sea Krait, a couple of beautiful cuttlefish, a tiny little Harlequin shrimp,   

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