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When it comes to wreck-diving, UK is probably one of the best dive destinations in the world. With thousands of ship wrecks scattered all across the isles, there is always a wreck an avid diver can explore in every known dive destination in the Kingdom. Some sites offer even more scenic spots and unique animal encounters under water that no other destinations can provide. Here’s a list of the top 7 dive sites in the UK.

Weymouth and Portland, Dorset
Weymouth has more than 120 wrecks within a 20-mile radius. The wrecks include warships, submarines, steam ships and freighters, among others. The most popular are the M2, the Salsette, the Avalanche, and the Aeolian Sky. Situated in the centre of the Jurassic Coast World Heritage Site, the area has an abundance of reef and ledge dives and are home to an amazing variety of marine life.

Plymouth, Devon
Plymouth is where experienced divers often explore the wreck of the HMS Scylla, a Leander-class frigate, sunk as an artificial reef in 2004. Also visible is the James Eagan Lane, a US Liberty ship that was sunk by a U-boat in World War 2. The area also has a smattering of shoals and reefs, in case divers opt for a change of scenery.

Porthkerris, Cornwall
Located on the eastern side of the Lizard Peninsula, the Drawna Rocks in Porthkerris boasts of the best shore dive in England. Just a short ride to nearby Manacles are numerous wrecks such as the Mohegan, the Volnay and the Spyridion, among others. Apart from the wrecks are pinnacles, drop-offs, reefs and an abundance of marine life. During the months of May to August, Porthkerris is visited by the second largest shark in the world, the Basking shark.

Skomer Island, Pembrokeshire, Wales
This is a marine reserve with a sharp drop-off that goes down to 45m. It is the site of the Lucy, a 52m intact coaster that sunk perfectly upright in 40m of water. It’s also home to frolicking grey seals, rare gorgonian fans (found in only a handful of areas in the UK), and various crustaceans.

Isle of Man
Located in the southwest of the Isle of Man is the islet Calf of Man, which hosts a dive site called the Burroo. This is rated as one of the top 50 dive sites in the world. Due to the strong tidal currents in the area, the marine life is abundant and diverse and may possibly be the best in all of the British Isles. There is an intact wreck of a Manx trawler, the Fenella Ann. Other wrecks worth seeing are the Ringwall, SS Liverpool and the Thracian. There is also an interesting cave worth exploring in the nearby Sugar Loaf dive site.

Farne Islands, Northumberland
This area is famous for its colony of 5,000 grey seals that often accompany divers. It offers scenic wrecks such as the Somali, Chris Christianson, Abyssinia, and Britannia. It also has a pinnacle, a wall, some reefs and rocks covered with soft corals and a huge, deep-water anemone, the Bolocera.

Scapa Flow, Orkney, Scotland
This is a natural harbour offering the best wreck diving in the UK. In the area are three battleships: the Markgraf, the Kronprinz Wilhelm and the Konig; and four light cruisers: the Coln, the Brummer, the Karlsruhe and the Dresden. These are popular wrecks among the 52 ships of the German High Seas Fleet that were scuttled near Cava at the end of World War 1. Due to their sizes, it usually takes several dives to view and appreciate just one wreck. Aside from these Dreadnoughts, there are also several wrecks of fishing boats, trawlers, cargo ships and a host of others scattered all over the harbour.

Divers will have their calendars full just navigating these 7 spots in the UK. There isn’t a lack of places to explore, and definitely not a shortfall in exciting things to see.

M2 submarine.

M2 submarine.



If you’ve spent the summer diving and find your gear needing some kind of an upgrade, now is probably the best time to buy. Too late for summer yet too early for next year’s dive season, you can upgrade your gear with this year’s current prices now, and be ready for next year’s season with brand-new equipment. Here are some of the latest goods that manufacturers have put out for 2013.

Rec/Tec BCDs
If you like exploring, going deeper and staying longer underwater, or maybe even considering doing some technical diving, a number of recreational and technical BCDs have been put out to address those requirements. The options make the transition from heavy recreational diving to light technical diving much easier, since you would no longer need to keep two sets of BCs. These rec/tec BCDs can be rigged to accommodate 2 cylinders, have at least 40lbs. of buoyancy lift –great for keeping you afloat comfortably even with an extra-heavy load – and come with more heavy- duty D-rings for attaching various accessories like a survive-balloon, flashlight, reel, slate, etc. Moreover, they’re made with tough, durable material that can withstand very rugged use. Some of these are the Apeks Black Ice, Oceanic Probe HLC and the Tusa BCJ-8000 X-Wing.

FINS: Modified Paddles
Once you’re hooked on diving you’ll often want to go where there’s a strong current as that’s where the action is – you can see pelagics and a whole lot of fish activity. Having a stiff fin can make a difference when moving against a strong current. But this is often hard on the leg muscles and can be a huge strain on the ankles. A split fin will work better and give you the thrust you need with less effort on your legs. But sometimes a split fin gets bent and can be an inconvenience. This year, no new developments have been made on the split fin though, and they’re probably on their way out anyway. Manufacturers like Mares, Aeris and Cetatek instead are banking on the modified paddles which give the desired stiffness for the propulsion that’s needed, yet with a flexible blade design that’s more compact– giving a shorter, lighter fin that’s more portable and suited for air travel requirements. They’re more comfortable, to boot. [No pun intended. ]

We all know the feeling of finding our drysuits unable to withstand the stress of wear and tear – a puncture here, a laceration there, or any kinds of minor abrasions in the most unexpected places. Imagine a leaking drysuit causing problems with your buoyancy! Knowing this, manufacturers have come up with drysuits made of specialized heavy-duty material that can withstand all kinds of stress. Companies like Bare have incorporated a high-tenacity nylon/butyl/polyester tri-laminate in its Trilam Pro Dry model; Waterproof USA’s D7 tri-laminate body is covered with an outer shell made entirely of Cordura; while USIA is playing around with nano-composite materials, creating a composite fabric that’s supposedly 15 times stronger than steel and 40 percent tougher than aramid fibers like Kevlar and Nomex — yet still lightweight and flexible. All these promise to give you years of trouble-free diving.

LED Flashlights
Everyone knows LED lights provide the punch of a high-wattage lantern with only a minimal power requirement but with a longer lasting battery life. Manufacturers are now coming out with smaller-sized units, small enough to fit into BC pockets but strong enough to be a primary light source during night dives. Such is the Ikelite Vega . It provides the convenience of bringing a single flashlight both for day — lighting holes and crevices – as well night dives. The Under Water Kinetics Aqualight E-LED on the other hand has adjustable light beams that can double up as a fill light, a spot light or focus light, or a floodlight for underwater video or still photography.

Lastly, SIZE AND WEIGHT still do matter . In 2012 we saw innovations for smaller and lighter gear. This year, the trend continues. More and more divers travel worldwide, so the demand for lighter, more compact equipment continues to be addressed. Meanwhile, we in the dive community have never had it this good.

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Dangerous Marine Life

 Dr Oliver Sykes

Marine life in tropical waters that pose hazards to man can be divided into four general categories: Contact irritants and toxins, Injected toxins, Ingested toxins and Predators . This month I will cover contact irritants and toxins.



All these animals possess nematocysts, a stinging apparatus that discharges on contact. Floating tentacles can retain active nematocysts, even after drying and there is a wide range of toxicity, from mild to severe.

Symptoms: Rapid onset of pain, varying from mild to severe. The rash is red, hot and swollen, usually linear. There is frequent pustule and vesicle formation and severe stings may cause muscle cramps, abdominal pain, fever, chills, nausea, vomiting, respiratory distress, and cardiovascular collapse. Fatalities are increased if there is pre-existing cardiac and respiratory disease. Box jellyfish (aka chironex, irukandji or sea wasp) may cause death in healthy individuals in less than 15 minutes.

Treatment: Use topical vinegar to neutralize undischarged nematocysts or sea water if copious volumes of vinegar are not available and then removal of remaining tentacles. Apply topical analgesics and steroids or intravenous versions if available. Treatment for shock or cardiac arrest may be required and therefore monitoring of pulse and blood pressure is required. Box jellyfish anti-venom is not universally available at all dive sites or smaller hospitals or clinics. Avoiding box jellyfish contact is of paramount importance. When diving in remote resorts in south-east Asia it is wise to ascertain the availability of anti toxin.



This is the only known venomous starfish, its arms having large spines with venom producing integument.

Symptoms: Rapid onset of swelling, redness and pain.

Cleanse the wound and apply topical antibiotics. Give tetanus protection.




Multiple slender spines puncture the skin and break off.

Symptoms: Immediate pain, joint pain, swelling and numbness.

Treatment: Remove spines, cleanse, topical antibiotics and tetanus protection. Soaking in hot water for 60-90 minutes is said to offer relief from the pain and swelling. Surgery is indicated for a foreign body reaction and if a joint capsule is punctured. Topical antibiotics and tetanus protection should be offered.



Some species eject a visceral liquid.

Symptoms: Redness, itching and pain. If eyes are involved, symptoms are similar to chemical burns and blindness can occur.

Treatment: Copious irrigation of the affected area.



Three species of sponges produce a rash on contact, including the red-beard sponge, fire sponge and poison-bun sponge.

Symptoms include: redness, joint pain and swelling.
Treatment: symptomatic with soothing lotions and topical steroids.



Coral may cause abrasions that become infected but there are no toxins associated with coral. Fire coral is not actually coral. It has nematocysts and is more closely related to jellyfish. On close inspection, fire coral has tiny hair like tentacles, unlike coral.



Question 1: What is shock?

Shock is a medical term for poor organ perfusion. The casualty looks pale, has a weak pulse, low blood pressure and may be drowsy or confused. There are many causes of this, but severe decompression sickness, arterial gas embolism, severe bleeding or anaphylaxis are the likely causes in divers. The treatment requires intravenous fluid resuscitation and needs medical support urgently.


Question 2: What is anaphylaxis?

Anaphylaxis is a life threatening reaction which is rare but can occur due/ as a result of to medications, commonly penicillin or stings, such as bee stings. Therefore it is possible to have an anaphylactic reaction to any of the above sea animals. The symptoms come on within minutes of exposure and include wheeze, itching, redness, confusion, drowsiness and shock.


Question 3: How do I treat anaphylaxis?

This may be indistinguishable from a severe jelly fish sting, but the treatment is the same. Therefore remove the cause, apply oxygen and intravenous fluid resuscitation but also adrenaline. People who are known to suffer anaphylaxis often carry adrenaline around with them. Also known as epinephrine, the injection is known as an epi-pen. Steroids, such as hydrocortisone and anti-histamines, such as chlorpheniramine, are used to prevent the reaction recurring. This is a life-threatening condition and patient’s should be taken to hospital for stabilisation or observation if responding to emergency treatment


Question 4: How do I avoid getting stung?

Find out about the dive site beforehand. Jellyfish appear seasonally and most others are rooted to the spot or at least move slowly. The best plan is not to touch anything but a thin wet suit is very effective at preventing stings. Be careful when it comes to washing the suit afterwards, as the nematocysts will still be active!


Question 5: What is Irukandji syndrome?

Irukandji syndrome is similar to anaphylaxis and is produced by a small amount of venom from a box jellyfish. There are muscle cramps, severe pain, a burning sensation in the skin and face, headaches, nausea, restlessness, sweating, vomiting, an increase in heart rate and blood pressure, and psychological phenomena such as the feeling of impending doom. The syndrome is delayed for 5–120 minutes and the treatment is symptomatic, with anti-histamines and anti-hypertensive drugs used to control inflammation and high blood pressure; intravenous opiates are used to control the pain. Irukandji are usually found near the coast, attracted by the warmer water, but blooms have been seen as far as five kilometres offshore. When properly treated, a single sting is normally not fatal, but two people in Australia are believed to have died from Irukandji stings in 2002.


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fire box








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Decompression Modelling

Dr Oliver SykesScuba diving may seem a long way from the class room and the point of theory may not be obvious, but it can be vital in making important decisions, especially about decompression models (aka tables). This article will outline some important theory and hopefully remind you that no dive profile is completely safe. Bear in mind that a model is only as good as it has been verified to be and there are too many factors involved to guarantee prevention of DCI.

A fundamental problem in the design of decompression models is that the rules that govern a single dive and ascent do not apply when bubbles already exist, as these will delay nitrogen elimination and equivalent decompression may result in decompression illness (DCI). Therefore repetitive diving, multiple ascents within a single dive and surface decompression procedures are significant risk factors for DCI.

The ideal dive profile creates the greatest possible gradient for nitrogen elimination from the tissues without causing bubbles to form. However it is far from clear whether this is possible. Some decompression models assume that stable bubble micro nuclei always exist. However, the dissolved phase decompression models are based on the assumption that bubble formation can be avoided. The bubble models make the assumption that there will be bubbles, but there is a tolerable total gas phase volume or a tolerable gas bubble size and limit the maximum gradient to take these tolerances into account. A number of empirical modifications to dissolved phase models have been made since the identification of venous bubbles by ultrasound in divers soon after surfacing.

Building Bert’s observation that dissolved nitrogen causes DCI, the first model that was verified experimentally, was developed by Haldane and is based on the following principles and concepts:

  • Nitrogen dissolves into tissues and becomes completely saturated after a certain amount of time. (Henry’s law)
  • The degree of saturation is determined by the ambient pressure, so that a given tissue above atmospheric pressure contains more nitrogen than the same tissue at 1 atmosphere.
  • The difference between the ambient pressure and a tissue’s partial pressure is called the pressure gradient.
  • On ascent, the partial pressure may be higher than the ambient pressure. But the body can tolerate some amount of pressure gradient without DCI.
  • If the pressure gradient becomes too high, the dissolved nitrogen cannot be eliminated quickly enough (by exhalation) and nitrogen bubbles form.
  • Partial pressure is the fraction of the total pressure that a single gas exerts in a mixture.
  • Tissue compartments are areas of the body that absorb gas at different rates and are categorized by how fast they uptake gas. Haldane introduced the concept of halftimes and suggested 5 tissue compartments with half times of 5, 10, 20, 40 and 75 minutes.

Tissue compartments do not correspond to anatomic tissues but one compartment will on gas and off gas at the same rate. Fast tissues on-gas and off-gas in shorter half-times than slow tissues. Areas that are well supplied by blood, such as the lungs and abdominal organs, absorb nitrogen faster than other tissues. Slower tissues include fat, fatty marrow and cartilage and saturation is reached when the pressure gradient is 0. This means after one half-time a compartment is 50% saturated, but it is not 100% saturated after two half-times, since each time the pressure gradient is halved. After two half-times a compartment is 75% saturated. After three, 87.5%. Four, 93.8 and for simplicity, we say a compartment is 100% saturated after 6 half-times.

How large can a gradient become before it’s a problem? Haldane assumed from his observations that the gradient could be a maximum of twice ambient pressure for all tissues. He assumed that an ascent from 30m (4 bar) to 10m (2 bar), or from 10m (2 bar) to the surface when saturated would not cause DCI. This was very conservative for shallow dives and not conservative for deep dives. In the 1960s Robert D. Workman of the U.S. Navy Experimental Diving Unit revised Haldane’s model with further experimental work to allow each tissue compartment to tolerate a different amount of supersaturation which varies with depth. This required a standardised ascent rate, which he took to be 18m per minute. His work allowed greater flexibility and safety to be built into tables for a range of depths and he introduced the term “M-value” to indicate the maximum amount of supersaturation each compartment could tolerate at a given depth. There are M-values for each compartment for each decompression stop. In no-decompression diving, however, we only have to be concerned with the values for the pressure at the surface. The PADI recreational dive planner grew out of Workman’s work and this is the reason why 18m per minute is the ascent rate required. The precise algorithms used in dive computers and tables are proprietary and therefore not available, but the PADI recreational dive planner now has a long safety history and is a useful benchmark.

We now have a complete model for predicting how nitrogen moves in and out of the tissues and at what point this process becomes a problem. However it remains a model and is therefore not true for every dive for every diver. So keep it conservative and stay within the limits of your computer!


PADI Recreational Dive Planner





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Oxygen Toxicity: Too much of a good thing.

Oxygen is necassary for life, but as divers we are exposed to higher partial pressures of oxygen (pO2 or ppO2) than normal. A partial Dr Oliver Sykespressure is simply the fraction of the total pressure that an individual gas takes up in a mixture of gases. Therefore 21% oxygen at sea level has a pO2 of 0.21 bar.

There are 2 main types of oxygen toxicty that we need to limit, which are pulmonary (lung) and neurological oxygen toxicity. In order to obtain energy from food, oxygen is used to break strong molecular bonds at the cellular level and is necessarily a fairly reactive species. As humans, we have evolved to use oxygen at 0.21 bar and even a pO2 of 0.5 bar begins to overwhelm the body’s repair mechanisms very slightly. This pO2 is only 50% O2 at sea level or 25% O2 at 2 bar or 10m. Therefore 50% oxygen is not recommended for over 24hrs in healthcare settings due to lung oxygen toxicity. Unless absolutely necassary. With much larger increases over shorter periods, such as a pO2 of over 1.4 bar during diving, neurological oxygen toxicity becomes the main worry. This is manifested in violent fitting (uncontrolled movements of the arms and legs) and is often fatal when diving. Unfortunately drowning is common and ascent is dangerous due lung barotrauma from a closed wind pipe. Therefore even a full face mask is not safe and the only treatment is to reduce the high pO2. Unfortunately stressors make neurological oxygen toxicity more likely during diving and include exercise, cold, poor vis, nitrogen narcosis, raised blood carbon dioxide levels and psychological stress. These are present on all dives and for everyone to some degree.

During recompression treatment, the chamber environment does not risk drowning and we minimise the stressors. We also use air breaks to limit the time spent at high pO2 levels and therefore use 100% O2 to greater depths than in water.

Overall, neurological oxygen toxicity is a very rare event in chambers and simply requires the diver to be taken off oxygen. Given that recompression is a treatment, the additional risk from oxygen toxicity is therefore acceptable and the pO2 limit is significantly higher in chamber treatments. But only with good reason.


Question 1:

What do you do if a diver fits underwater?

100% O2 should not be breathed below 4-6m, as this gives a pO2 of 1.4 to 1.6 bar. If a diver is using breathing gas mixes enriched with oxygen and then fits at depth, the cause is likely to be oxygen toxicity and switching to the wrong mix can cause this. Ascent is clearly dangerous due to lung over expansion injury, but may be the only way to ensure help can be given. Make sure you are aware of this problem and are able to cope with it. Essentially, follow the guidence from your training agency at all times.


Question 2:

Are there any preceding symptoms prior to an oxygen toxicty fit?

Yes there are. These include blurred vision, ringing in the ears, nausea, twitching, irritability (anxiety, restlessness) and dizziness, which can progress to convulsions (fitting). These can be remembered with the letters VENTID-C  and can be difficult to pick up when diving. (Vision, Ears, Nausea, Twitching, Irritability, Dizziness, Convulsions)


Question 3:

What happens if someone has an oxygen fit in the chamber?

Our chamber attendants are trained to recognise the preceding symptoms and will take the diver off oxygen. If there is a convulsion, then they will pad the moving limbs and the fit will stop once off oxygen. Chamber pressure must not be altered during a fit. There is no long term damage, it is not epilepsy and has no impact on future diving or driving. We would then decide whether to continue the treatment or shorten it, depending on the reason for treatment and the state of the patient.


Question 4:

What is pulmonary (lung) oxygen toxicity?

The airways become narrower as a result of inflammation. There is often midline chest pain, cough and reduced lung function tests. Diving is unlikely to produce sufficient oxygen exposure. However some of the more extensive treatments for decompression illness may cause a degree of pulmonary oxygen toxicty. Thankfully this is often completely reversible.


Question 5:

Are air breaks useful in preventing oxygen toxicity at sea level?

Important: Do not use air breaks when using oxygen at the surface in an emergency situation, this is unnecessary and deprives the diver of a very important treatment.


A video from Divers Alert Network DAN follow the link below :

CNS Oxygen Toxicity – Richard Vann PhD

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Flying after diving and flying after recompression

Dr Oliver Sykes

Dr Oliver Sykes

Many divers fly home after a diving holiday, but how many realise that this might have consequences and there are guidelines on how long they should wait? We often see divers at the hyperbaric unit who clearly have not waited long enough before flying and have developed decompression illness during the flight. Thankfully these are a tiny minority of divers and are not usually severe cases, but time to treatment is often delayed and can result in residual symptoms.


Why do we decompress during a flight? Commercial aircraft are pressurised to less than an atmosphere for a number of reasons, primarily financial. No planes are airtight and therefore leak. This requires compressors to maintain cabin pressure, which requires expensive fuel. However the pressurised plane is then heavier and this requires more fuel too. Therefore pressurising the fuselage to less than 1 atmosphere makes flying cheaper and we all decompress on the flight home. This is not a problem unless you’ve been diving recently. PADI appears to follow the DAN guidelines on flying after diving:


The following guidelines are the consensus of attendees at the 2002 Flying After Diving Workshop. (Alert Diver, November/December 2002, www.diversalertnetwork.org/files/FADWkshpBook_web.pdf) They apply to air dives followed by flights at cabin altitudes of 2,000 to 8,000 feet (610 to 2,438 meters) for divers who do not have symptoms of decompression sickness (DCS). The recommended preflight surface intervals do not guarantee avoidance of DCS. Longer surface intervals will reduce DCS risk further. For a single no-decompression dive, a minimum preflight surface interval of 12 hours is suggested. For multiple dives per day or multiple days of diving, a minimum preflight surface interval of 18 hours is suggested. For dives requiring decompression stops, there is little evidence on which to base a recommendation, and a preflight surface interval substantially longer than 18 hours appears prudent.


In reference to these guidelines, scubadoc states (http://www.scuba-doc.com/flyngaft.htm):

The above is for sports diving and should not apply to commercial diving or nitrox diving. Because of the complex nature of DCS and because decompression schedules are based on unverifiable assumptions, there can never be a fixed flying after diving rule that can guarantee prevention of bends completely.


After treatment for decompression illness, there also should be some time for recovery before flying. Damage from the bubbles of decompression illness is the result of many interactions, but one of the most basic problems is lack of oxygen (low partial pressure of oxygen) in the tissues. Unfortunately a lower partial pressure of oxygen in the tissues also occurs with the decompression and lower cabin pressure involved in commercial flights. Therefore flying after treatment for decompression illness should be discussed with the diving doctor. The US Navy Diving Manual (Rev 6) states: Patients with residual symptoms should fly only with the concurrence of a Diving Medical Officer. Patients who have been treated for decompression illness or arterial gas embolism and have complete relief should not fly for 72 hours after treatment, at a minimum.


Question 1:

Can I fly home immediately after a 40 min Discover Scuba session to 5m?


No. This is a single no decompression dive and you must wait at least 12 hours.


Question 2:

I am going to drive home over some hills that are around 1000ft above sea level. Is this OK within 12hrs of surfacing?


This is probably OK, but be aware that symptoms may still occur,especially if you ascend to altitude sooner rather later after surfacing. Anything below 2000ft (610m) should be fine. There are plenty of hills within the UK that are over this height and I have seen divers develop decompression illness as a result of driving home over the Pennines, for example.


Question 3

As a diving officer, what should I advise helicopter crews, if a diver requires airlifting to a chamber?

This needs to be discussed on a case by case basis with the diving doctor and the service providing the aircraft as there is a risk of worsening the decompression illness but there are also significant risks to flying low.

Advice usually includes:

Keep the diver on 100% oxygen

Use an aircraft pressurised to 1 atmosphere if available

Fly as low as possible, preferably below 1000ft


Question 4

I have a commercial diving medical from the Health and Safety Executive, what are their recommendations about return to diving after DCI?

Commercial diving is very different to sports diving, with far more control over depths, times, ascent rates, multilevel diving and number of dives per day. However the diver has less control over when he/she actually dives. Its therefore not really reasonable to compare the two. I would recommend that you discuss it with the diving doctor that treated you. The HSE guidelines can be found at: www.hse.gov.uk/diving/ma1.pdf


Question 5

Where can I get more advice on flying, diving and decompression illness?


The Divers Emergency Service
Telephone: +44 (0) 7999 292 999


We are based at London Hyperbaric Medicine in the East end of London. You can phone us from anywhere in the world and we will help you find your nearest chamber and diving doctor

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Clearing your Ears In Water and Other Pressurised Environments.

As a diver, clearing your ears may be second nature. However we all had to learn at some stage and damage to your ears from over forceful clearing techniques is possible. So a quick reminder of the many techniques available may be useful.

The theory:

Your ears have an external tunnel that ends with a flexible ear drum. Imagine a real drum that gets compressed if you increase the pressure around it. (See a. in Figure 1.) The frame of the drum is like your skull and the skin of the drum is like your ear drum. Thankfully your ears differ significantly from a real drum! (See Ear anatomy picture below) For example, ach ear has a tube (See b. in Figure 2), which runs from behind the ear drum to the back of your throat. To stop your ear drum being pushed inwards, you need to increase the internal pressure behind your ear drum. You can do this by actively pushing air up these tubes. Unfortunately these tubes can work like flutter valves, hence can get stuck closed if you try too hard or allow the pressure to get too great before clearing your ears. Blockage can also occur when you have a cold and diving may not be possible. So you must not dive if you can’t clear your ears.

The external water pressure on the drum (Figure 1) and internal pressure generated by you (Figure 2):


The Techniques:

Try any of the techniques below early and often but perhaps start with 1. and  2. Everyone does it differently and works out which method works best for them. You will know when you have been successful when your ears “pop” and your hearing and perhaps balance returns to normal. Some of these are easier, in a recompression chamber rather than when diving.

1.         Swallowing, which is known as the Toynbee manoeuvre, drinking, sucking sweets, yawning, coughing, blowing your nose are all things we are used to doing and can be useful.

2.         Pinch your nose, close your mouth and try to blow out of your ears gently. Too hard will not work and can do damage. Watch other divers if you need to know how hard to try. This is known as the valsalva manoeuvre.

3.         The Lowry technique involves using all the above.

4.         Edmonds technique involves rocking the lower jaw from left to right and up and down and forwards and backwards, so that the lower teeth project in front of the upper teeth.

5.         Edmonds 2 advice: “Block your nose, close your mouth, then suck in your cheeks then puff them out quickly.”

6.         Try an otovent. (In chamber only) Occlude one nostril and blow up the balloon with the other nostril.  [youtube]

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7.         A difficult one to describe is the Frenzel manoevre. This involves closing the mouth and nose and push the back of your tongue up to the roof of your mouth as you swallow.

8.         Some people get good at clearing their ears and can do it without seeming to do anything. This is an advanced technique not discussed here, but everyone started off by holding their nose and blowing gently out of their ears!

Blocked or painful ears are very common while the pressure is increasing and difficulty clearing your ears is nothing to be ashamed of, but pain is a sign of possible barotrauma and definitely to be avoided. Some people simply find it difficult, but the longer and deeper you leave it, the less likely you will be able to clear your ears.

Ear Anatomy


(Kindly reproduced from Wikipedia)

Question 1: Who was Valsalva?

He was a 17th Century Italian anatomist, who described this method for expelling pus from the middle ear through a perforated ear drum.

Question 2:

Can I cause a perforated ear drum by clearing my ears too hard?

Yes, but this thankfully only happens rarely and is probably most commonly associated with a pre-existing weakness in the ear drum. Round window rupture and disruption of the middle ear bones are also possible and barotrauma is possible from as little as 2m. Grommets are artificial tubes placed in the ear drum to allow passive ear clearing, but completely preclude diving. Perforated ear drums seem to me to be most commonly caused by jumping into water ‘ear first’

Question 3:

Can I use decongestants to help clear my ears?

Definitely avoid these and do not dive if you cannot clear your ears. If the medications wear off, the ‘reverse block’ may cause barotrauma, intense dizziness and prevent ascent due to pain.

Question 4:

How can I be sure that I am clearing my ears properly?

Practise gently in water and follow the advice from your instructor. If clearing your ears is still causing pain, avoid diving with an upper respiratory infection. Try descending feet first to reduce venous congestion and using the anchor chain to fine tune to the speed of descent. Small ascents may relieve a blockage due to the flutter valve effect. Finally, there may be a correctable cause and a visit to your doctor may be useful.

Question 5:

How can I tell the difference between inner ear DCI and inner ear barotrauma?

This is an important question as the treatments are entirely different. Inner ear DCI requires recompression, but this will worsen inner ear barotrauma. However both may present with dizziness, nystagmus, (eye flicking) nausea, vomiting and unsteadiness. Both are serious conditions and require assessment by a doctor experienced in diving medicine. Inner ear barotrauma is more likely when symptoms begin on compression, with a shallow dive profile and forceful ear clearing. There may be associated ear barotrauma signs and symptoms, such as pain, fullness, unable to clear your ears and red/damaged ear drum.

Whereas the symptoms of inner ear DCI may start after the beginning of the ascent from longer, deeper, mixed gas dives and there may be signs and symptoms of neurological DCI, such as numbness and weakness in the limbs

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The History of Diving Chambers

Perhaps the first recorded diver, who was not a free diver, was Alexander the Great. He was said to have been lowered in to the Bosporus strait in a glass barrel in 320BC. Not much had improved by 1620, when Drebbel developed a diving bell which must have been severely limited as air was only replenished at one atmosphere. It was Henshaw, an English clergyman, who possibly constructed the first pressurized chamber for people on land in 1662. He called it the ‘domicilium’ and it was large enough to contain a piano and smoking room. Clearly this was before current theories on sound waves and bombs. At the very least, the denser air at pressure have altered the pitch and made the pipes burn much quicker! Sir Edmund Halley, of comet fame, probably developed the first useful diving bell, in which people remained underwater in the Thames for an hour and a half in 1691. Barrels of air were brought down to them which would have flushed out the carbon dioxide and replenished the oxygen. Perhaps also the first open circuit! The earliest recorded attempt at protecting a diver in rigid armour was made by John Lethbridge of Devonshire, England in 1715. The oak suit had a viewing port and holes for the diver’s arms and water was kept out of the suit by means of greased leather cuffs. The device was reported to have made many working dives to 60ft/18m. In 1774 Freminet, a French Scientist, reached a depth of 50ft and stayed there for an hour, using a helmet with compressed air pumped through a pipe from the surface.

Pressure vessel technology really only developed in the early to mid-1800s with the construction of bridges and tunnels. Triger developed open caissons in France, but water leak was a major problem and in 1830 Admiral Lord Thomas Cochrane patented the technique of using compressed air to exclude water. This technique was successful but was soon followed by reports of decompression illness in the workers. In 1854, Pol and Watelle reported that relief was obtained by workers who went back into the tunnels and Paul Bert showed that bubbles in the tissues during decompression consisted mainly of nitrogen in 1871. But it was only after the building of the New York tunnels under the Hudson and East rivers in 1889 and 1893 that the benefits were fully established. Early chambers at tunnelling sites were nothing more than boilers mounted horizontally with an airtight door at one end.

While Scheele discovered oxygen first in 1772, Priestly published first in 1775 and Lavoisier correctly described combustion in 1775. For hyperbaric oxygen, it was Drager in Germany who first realised the potential benefits of oxygen under pressure and devised a system for the treatment of decompression illness in 1917, but it was Benke and Shaw who first finally used hyperbaric oxygen to treat decompression illness in 1937. Official regulation and standards for hyperbaric oxygen therapy came together with The Undersea Medical Society, which was formed in the United States in 1967, and added, hyperbaric to its name in 1986. Diving chambers are now used for more than just recompression and there is a whole speciality called hyperbaric medicine. The Undersea and Hyperbaric Medicine Society publishes a complete list of indications for hyperbaric oxygen at http://membership.uhms.org/?page=indications


Question 1: Why is decompression illness also known as the Bends?

In the USA, the ‘Grecian bend’ was part of popular fashion at the time of building the Brooklyn Bridge, having been introduced into America as a dance move in the mid-1850s. This replicated the position adopted by the workers, presumably with severe girdle pain decompression illness and probably gave ‘the bends’ its name. One can imagine that the association with female attire provoked much joking amongst the men and contributed to the long history of divers making light of the pains of decompression illness.

Question 2: What does the word hyperbaric mean?

Hyper- comes from the Greek word ‘hyper’, meaning over or above and -baric refers to pressure, as in barometer and has its origin in the Greek word ‘baros’, meaning weight. In current scientific language, hyperbaric is an adjective used to describe an environment that is at pressure greater than atmospheric.


Question 3: What is the Paul Bert effect?

Central nervous system oxygen toxicity was first described by Paul Bert and is sometimes referred to as the “Paul Bert effect”. He showed that oxygen was toxic to insects, arachnidsmyriapods, molluscs, earthworms, fungi, germinating seeds, birds, and other animals. In humans this occurs as result of breathing increased partial pressures of oxygen and is the reason for limiting pO2 to 1.4 bar while diving. There is an initial syndrome of anxiety, twitching and nausea which develops into seizures which can easily be fatal underwater.


Question 4: What type of chambers exist today?

Hyperbaric chambers are classified into monoplace and multiplace chambers. Monoplace chambers are generally pressurised with oxygen and take one, or occasionally 2 people. There is therefore no need to where a mask, but the oxygen requirements are high as there is continuous flushing of the chamber. Multiplace chambers are more appropriate for emergencies as there is more room and allows for a chamber attendant and better monitoring. These chambers are pressurised with air and therefore require the patient to wear a mask or hood to breath oxygen at the correct pressure. Other features of multiplace chambers include size, entrance locks, and medical locks.

Question 5: Why did the British Navy use goats to research diving tables?

Haldane and the British Navy produced the first theory and set of tables determining ‘safe’ decompression schedules in 1906. While these contained fundamental flaws, the rates of decompression illness were reduced. It is said that goats were used instead of divers in the research because they are of similar size to humans, stamp their feet when in pain from decompression illness and have useful handles (horns) for getting them in and out of chambers. The unfortunate flock of goats was only been disbanded in Portsmouth about 20 yrs. ago, citing huge vets bills. No wonder!


Tunnelling work.




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‘Cutaneous Manifestations of Decompression Illness’ Also known as ‘Skin Bends’

Because the bends can present in so many ways, the problems it can cause in the skin can be overlooked. Especially as rashes after diving are common. The overarching title: ‘Decompression Illness’ (DCI) includes decompression sickness (DCS) and arterial gas embolism (AGE), reflecting the 2 theories by which bubbles cause problems. However skin bends can be associated with both processes and therefore a descriptive classification of symptoms is the most useful method of communicating information. So what could be easier to describe and treat than a skin bend? However there seems to be a few problems.

Skin bends may not be seen as part of decompression illness. Rashes are common and determining whether a skin bend is present can be difficult. A skin bend is a rash with poorly defined edges, there may be varying degrees of redness, it may be itchy, may make the skin seem more like marble and may occur in a single area or in multiple areas. Finally the rash of a skin bend is not caused by sunburn, suit squeeze, harness straps, skin infections, bites or scratching, although all these may be present and confuse the picture. Simple cases of itching, burning and increased warmth occur after many dives and probably should not be recompressed, but should still be discussed with a diving doctor. In terms of severity, next comes cutis marmorata. This is described as marbling of the skin. Blood vessels constrict and dilate in different areas over a small patch of skin, producing areas of pale skin and redder areas. This then looks like marble and should certainly be discussed with a diving doctor.

At the other end of the scale, livedo reticularis is the most severe form, as seen in the picture above, and involves patchy, reddish-purple mottled areas, especially around the shoulders and trunk. This can be intensely itchy, due to a local vascular reaction from bubbles in the tissues below the dermis, and is clearly a systemic manifestation of DCS. These divers must be treated. Another skin symptom to take seriously occurs with blockage of the lymphatics with bubbles, resulting in swelling and a peculiar pitting of the skin called peau d’orange (meaning skin of the orange) and again is evidence of a more serious form of DCS, known as lymphatic decompression sickness.

In the past skin bends on the limbs were not considered severe enough to warrant treatment. However all symptoms that start after decompression has begun, however minor, can herald severe DCI and must be assessed by a diving doctor. There have also been recent reports of an association with skin bends with patent foramen ovale (PFO) and there are now recommendations that some divers with this condition be checked for PFO.

In order to help us improve our recognition of skin bends, please help us with our Skin Bend Image and Information Bank. Scroll down the page to find the correct article at: http://www.londonhyperbaric.com/category/blog and download the 3 forms. Please print off and fill in the consent form and questionnaire and send these to the address given. Finally lease email the relevant photos to the secure NHSMail email address: o.sykes@nhs.net. This will in no way affect your treatment by the Divers Emergency Service or London Hyperbaric Medicine.

We do need written consent, not emailed consent. Sorry!

Picture reprinted from The Lancet, Vol. 377, Vann RD, Butler FK, Mitchell SJ, Moon RE, ‘Decompression Illness,’ Pages 153-64, 2011, with kind permission from Elsevier.



Information for Participants

Research study: Skin Bend Image and Information Bank

We would like to invite you to be part of this research project.

You should only agree to take part if you want to and it is entirely up to you. If you choose not to take part there won’t be any disadvantages for you and choosing not to take part will not affect your access to treatment or services in any way. Please read the following information carefully before you decide to take part; this will tell you why the research is being done and what you will be asked to do if you take part. Please ask if there is anything that is not clear or if you would like more information. If you decide to take part you will be asked to sign the attached form to say that you agree. You are still free to withdraw at any time and without giving a reason.

Details of study:

There are many reasons for rashes after diving, but sometimes these are due to decompression illness. (The Bends) We at London Hyperbaric Medicine (LHM) would like to collect anonymous images and information on rashes that occur up to 72 hrs after diving in order to form a bank. This will be published on the LHM web site and blog (http://www.londonhyperbaric.com/category/blog), in a Sport Diver article (http://www.sportdiver.co.uk/), for teaching purposes, in a medical journal and in The Anaesthesia UK Image Bank, (http://www.frca.co.uk/imgdefault.aspx) if accepted for publication. This will form very useful resources for doctors and divers.

Every effort will be made to ensure that you are unrecognizable from the pictures. However this cannot be absolutely guaranteed. Once the pictures are on the web site, you may request for yours to be removed at any time.


If you think you may have skin decompression illness, any other form of decompression illness or serious cause for a rash, then contact the Divers Emergency Service immediately on:

+44 (0)7 999 292 999

In order to help maintain your safety and confidentiality, the images will not be free for all to use. LHM will need to hold the copyright to the images, but will not use the images in any other fashion without express prior consent from you.

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By Dr Oliver Sykes from Sport Diver/Divers Emergency Service

Drowning is death due to lack of oxygen (hypoxia) from suffocation caused by submersion in water and near drowning occurs where the victim survives an event that nearly resulted in drowning. According to the World

Health Organization, drowning is the 3rd leading cause of unintentional injury death worldwide, accounting for 7% of all injury related deaths (est. 388,000 deaths by drowning in 2004, excluding those due to natural disasters).


People in difficulty in the water may be in distress but still have the ability to keep afloat, signal for help and take actions. However those that drown fall into two categories: Passive or active drowning. In passive drowning people suddenly sink due to a change in their circumstances. Examples include people who drown in an accident, or due to sudden loss of consciousness or sudden medical condition. Active drowning occurs in non-swimmers and the exhausted or hypothermic at the surface, who are unable to hold their mouth above water and are suffocating due to lack of air. Instinctively, people in such cases perform well known behaviours in the last 20 – 60 seconds before being submerged, representing the body’s last efforts to obtain air. Notably such people are unable to call for help, talk, reach for rescue equipment, or alert swimmers even feet away, and they may drown quickly and silently close to other swimmers or safety.

Drowning can take place in other circumstances than those in popular awareness. For example, children have drowned in buckets and toilets, but most drownings occur when the victim is in water (90% in freshwater (rivers, lakes and pools), 10% in seawater). Drownings in other fluids are rare, and are often related to industrial accidents. Shallow water blackout is caused by hyperventilation prior to swimming or diving. The primary urge to breathe is triggered by rising carbon dioxide (CO2) levels in the bloodstream but hyperventilation artificially depletes this and leaves the diver susceptible to sudden loss of consciousness without warning from hypoxia on ascent as the oxygen levels fall. There is no bodily sensation that warns a diver of an impending blackout, and victims become unconscious and drown quietly without alerting anyone. They are typically found on the bottom. Secondary drowning occurs after inhaled fluid irritates the lungs, which then leak fluid and make breathing and ventilation more difficult.  Certain poisonous vapours, gases or vomit can have a similar effect. The reaction can take place up to 72 hours after a near drowning incident, and may lead to a serious condition or death. Therefore all cases of near drowning should be observed in an appropriate healthcare setting after the event. Examinations on human drowning victims show that there appears to be little difference between drowning in salt water and fresh water.



Optimal pre hospital care is a significant determinant of outcome in the management of immersion victims worldwide. Bystanders should call the emergency services immediately and, as in any rescue initiative, initial treatment should be geared toward ensuring adequacy of the airway, breathing, and circulation (ABCs). Rescue may therefore simply involve bringing the person’s mouth and nose above the water surface but an individual may be rescued at any time during the process of drowning.  No two cases are entirely alike. The type of water, water temperature, quantity of water aspirated, time in the water, and individual’s underlying medical condition all play a role. For example hypothermic patients can appear dead and therefore all cases should be warmed up and an unconscious victim rescued with an airway still sealed from laryngospasm stands a good chance of a full recovery. Therefore bystanders and rescue workers should never assume the individual is unsalvageable unless it is patently obvious that the individual has been dead for quite a while.


Unfortunately a drowning person may cling to the rescuer and try to pull himself out of the water, submerging the rescuer in the process. Thus it is advised that the rescuer approach with a buoyant object, or from behind, twisting the person’s arm on the back to restrict movement. After a successful approach, negatively buoyant objects such as a weight belt are removed. The priority is then to transport the person to the water’s edge in preparation for removal from the water. The person is turned on their back with a secure grip used to tow from behind. If the person is cooperative they may be towed in a similar fashion held at the armpits. If the person is unconscious they may be pulled in a similar fashion held at the chin and cheeks, ensuring that the mouth and nose are well above the water. 

Airway and C-Spine

Pay attention to cervical spine stabilization if the patient has facial or head injury, is unable to give an adequate history, or may have been involved in a diving accident or motor vehicle accident. If possible, the individual should be lifted out in a prone position. Theoretically, hypotension may follow lifting the individual out in an upright manner because of the relative change in pressure surrounding the body from water to air.  In the patient with an altered mental status, the airway should be checked for foreign material and vomit. Debris visible in the oropharynx should be removed with a finger-sweep manoeuvre. The abdominal thrust (Heimlich) manoeuvre has not been shown to be effective in removing aspirated water; in addition, it delays the start of resuscitation and risks causing the patient to vomit and aspirate.


Breathing and Circulation

Rescue breathing should be performed while the individual is still in water, but chest compressions are inadequate because of buoyancy issues. Once on firm ground, chest compressions are performed if the patient is pulseless, and if they are not breathing rescue breaths. The highest concentration of oxygen should be given as early as possible. If available, continuous non-invasive pulse oximetry is optimal. If the patient still has difficulty breathing on 100% oxygen or has a low oxygen saturation, use continuous positive airway pressure (CPAP) if available and if you are trained to do so. Also consider early intubation, with appropriate use of positive end expiratory pressure. Higher pressures may be required for ventilation because of the poor compliance resulting from pulmonary oedema. Transfer the patient to the nearest appropriate medical facility and consider that treatment for hypothermia may also be necessary.