Oxygen: Why we need it on every Dive

Besides the obvious (that we need Oxygen to live and it is in the air that we all breathe, under water and above) why do we need to have Oxygen for every Dive we make.

Working in a country, like Cyprus, where the Diving Conditions are relatively easy and the rate of incident
are pretty low, can Dive Centres and Diving instructors be forgiven for not having emergency Oxygen with them on every Dive they make?

Before we go on to discuss this issue, have a read of this Article from DAN about a 14 year old boy who had a diving incident in Malaysia where no Emergency Oxygen was immediately available.

Oxygen Administration is the recommended first aid for the majority of Scuba Diving Incidents ranging from; Decompression Sickness & Arterial Gas Embolism (Decompression Illness) to Near Drowning. Research has shown that the earlier 100% Oxygen can be given to a patient to breathe, the less severe and damaging the Injuries are likely to be.

Of course, the first step is to Identify and recognise that there is a problem, so let's have a quick look at some of the signs and Symptoms that may indicate Oxygen is Needed.

Decompression sickness	Arterial Gas Embolism
Signs
Skin rash	Bloody froth from mouth or nose
Paralysis, muscle weakness	Paralysis or weakness
Difficulty in urinating	Convulsions
Confusion, personality changes, bizarre behaviour	Unconsciousness
Loss of memory, tremors	No breathing
Staggering	Death
Collapse or unconsciousness
Symptoms
Fatigue	Dizziness
Skin itch	Blurring of Vision
Pain in joints or muscles	Areas of decreased sensation
Dizziness, vertigo, ringing in the ears	Chest pain
Numbness, tingling and paralysis	Disorientation
Shortness of breath

Table above taken from wikipedia

There are no definitive tests or unique signs to confirm DCS "in the field" and many of the symptoms are similar to those of other illnesses but if you suspect a Diving Incident, your first step should be to administer Oxygen.

Why Oxygen?

Oxygen is a life sustaining, essential gas. Although it does become toxic under higher Partial Pressures (below 6metres underwater), it is required for life in normoxic levels.

In a diving injury, bubbles that can form on ascent can block the blood supply to the body tissues, leading to damage and/or obstructions to Gas Exchange ie Oxygen reaching the tissues.

We administer 100% Oxygen in any Diving incident because it allows a higher concentration of Oxygen to enter the body, altering the pressure gradient for gas exchange and facilitating Inert Gas (Nitrogen and Helium) removal. 

The Oxygen can also help to decrease the size of any bubbles that may have formed on ascent, Oxygenate the Hypoxic Tissues (ones that weren't getting enough Oxygen to survive), ease breathing and relieve Symptoms.

There are also results to suggest there is a lesser risk of residual symptoms after Hyperbaric Treatment when Oxygen is administered early because the increased levels of Oxygen have prevented further damage being caused to the tissues by bubbles and hypoxia.

So, as you can see, having a supply of emergency Oxygen should be on every pre dive safety check list. Every Dive Centre and Diving Instructor/guide should have a sufficient supply with them to ensure that they can administer Oxygen First Aid, if needed, as soon as possible. The supply should be sufficient to allow the patient to continue breathing 100% Oxygen until emergency assistance arrives or you can reach the nearest hyperbaric treatment centre.

There have been several instances where our emergency Oxygen has been used on Dive Boats because Divers do not have their own and while I do not know any divers or diving centre that would withhold Oxygen from someone who needs it, it isn't acceptable to rely on someone else to provide it.

If every Diver relies on another diver to supply Emergency Oxygen, there will come a time when there is none available!

So, when you plan your next dive trip, don't forget to make sure there will be Emergency Oxygen First Aid available on every boat, in every truck/vehicle and someone available who knows how to operate it. 

If in doubt about a Diving Emergency, you can call the Divers Alert Network Emergency International Helpline and they can assist you with the steps you need to take and to find the nearest treatment centre. Keep this number with your emergency Oxygen and take it on every dive.

DAN Emergency Helpline Number: +1-919-684-9111

Feeling Hot Hot Hot... Summer Diving in a warm climate

We are now hitting the height of the summer season here in Cyprus and the land temperatures are hitting the high 30s, low 40s (degrees centigrade) in the shade.

Even the water temperatures are getting towards the 30 degree mark, so to cool down, you need to
find a nice thermocline, which is usually around 25metres underwater.

Although these soaring temperatures and hot lazy days are fantastic for the thousands of tourists that flock to this tiny mediterranean island, there are a few things we all need to consider, especially for us Divers.


Firstly, there is the dreaded Sunburn.

As Divers, we spent an inordinate amount of time outside and in the sunshine wearing little more than a swimsuit. At the sea's shore or on the dive boat, there is usually a lovely sea breeze that keeps you cool and you can easily burn without realising it.

Even under the water, you are not safe from the sun's rays, as you can tan or burn through the water. Quite often, this happens faster than on land.

So, when you are diving in a hot climate like Cyprus, use a high factor Sunscreen to protect yourself. Apply liberally and often and even before getting in the water because nobody wants to put on a well fitting neoprene suit over the red raw burn of the Sun.


The next big issue of Hot countries is Dehydration.

In colder climes such as the UK, we are told that we should drink approximately 8 pints of water a day. That is around 4 litres. When you get to hot countries like Cyprus you will need much much more than this.

Imagine all that water you lose through perspiration. It all needs to be replaced and unfortunately, beer does not help to rehydrate. So, consider swapping out a few of those alcoholic drinks for the good old "nectar of the gods"... water

As a Scuba Diver, Hydration is extremely important from a decompression point of view. Dehydration can cause a restriction in the flow of blood to the muscles in the body and this restriction can compromise off-gassing potentially leading to bubble formation and a "bend".

There are many combined factors that can lead to dehydration for a diver in a hot country. Not drinking enough water, Drinking too much alcohol, Sweating, Breathing dry air from a compressed air cylinder and of course, the spaceman effect (the need to urinate in a weightless environment) all add up to make this a very real problem.

The final topic I will touch on is Overheating

Here in Cyprus, we have extremely hot land temperatures at this time of year. When we kit up for our dives, it can be very easy to overheat.

Our suits are designed to keep our bodies warm but on land, this can be dangerous for us. With the sun beating down, we sweat and our core temperature is elevated over and above what it should be. If our protective mechanism of sweating cannot keep up, we risk heat exhaustion and/or heat stroke.

So, why bother with the suits if the temperature is that hot you ask?

Unlike many tropical destinations, the waters around Cyprus are quite deep and although the water temperature at the surface of the sea can reach above 30 degrees, the colder waters from the deep take longer to warm up.

At the moment, the sea temperatures here are 28 degrees down to approximately 25metres and, at this point the warmed up waters from the shallows meets the colder water from the deep.

You are descending through the water, like you are in a warm bath when from the corner of your eye, you spot a slight colour change and a line of shimmering water. Suddenly, as you descend you feel the temperature drop from 28 degrees to 22 and you are extremely grateful that your instructor told you to put a wetsuit on.

This point where the cold water meets the warm water is called a thermocline and there is nothing more enjoyable than coming back up through it from cold water to warm.

So, if you are planning a dive trip to a wam country this year, remember to stay healthy, you must stay Hydrated, use a high factor sun protection and keep to the shade when kitting up, only putting on the wetsuit at the last moment when needed.

Most dive centres in hot countries will provide water for their divers to stay hydrated but, you should always have your own with you too... just in case. You can not go wrong with carrying some hydration salts also just to help along the way.

Enjoy the sunshine and enjoy the dives... I know we will

Scuba Diving- A Beginner's Guide

Thinking back over my years as a diving instructor in Cyprus, I began to think about the number of Divers that have come through the doors and the mis-understandings and cons I have seen over the years.

The problem is, that unless you know better, you do not generally know what to expect with a Beginner's Diving course, such as PADI Open Water, BSAC Ocean Diver etc but there are a few things that you should get  with any of these courses.

Access to Diver Materials

Usually in each Diving course that you take, the chosen Agency produces a manual containing all the
relevant Diver theory you will need to pass the course and build a solid knowledge base for future training and Diving.

PADI insist that each diver have their own manuals for each course, enabling the diver to have a reference to any of the information from said course in the future, which is a very good idea because, as a beginner, trying to cram all that information into 4 days means only a fraction of it will be retained and a lot of it will probably be forgotten quite quickly.

With the advent of online learning, manuals can now be replaced with an online code, which allows you to do the knowledge portion of the courses on-line. Fantastic for some but, I still like to have the solid manual in my hands and it is always best to check whether it will be cost efective for you. I have found the online training usually works out to be more expensive and you don't have the benefit of your instructor there with you to answer questions you might have along the way.

By the time you get to see your instructors, you will have forgotten what those questions were!!

Skills Sessions and Open Water Dives

Each agency breaks down the Diving Courses into Open Water Dives and Confined Pool Sessions. An easy way to check what you should be doing on the Courses is to check out the Agency's own website and it will describe the components of the courses.

So, for example, the PADI Open Water Course has 5 Knowledge Development Sessions, 5 Confined Water Skills Sessions and a minimum of 4 Open Water Dives.

BSAC Ocean Diver has some theory and knowledge development, 5 Confined Water Skills Sessions and 5 Open Water Dives.

No portion of the course should be signed off until the diver is comfortable and competent at that level. Remember that these courses are supposed to take a minimum of 4 days and trying to squeeze it into 2 or 3 is not going to produce high quality divers that can look after themselves in the water.

At Scuba Tech Diving Centre, we try to give our student divers even more time for diving by incorporating an extra Open Water Dive after each skill session. This is beneficial to the Diver, as you can only improve at Scuba when you spend more time in the water. However, I stress this is an additional dive and does not count as one of the 4 mandatory Open Water Course Dives. Do not allow the Dive Centre to combine your Skills Sessions with these compulsory Dives, as it is breaking standards and, as a trainee, you will not benefit from less time in the water!

A Proper Certification Card



 I think back to around seven years ago and a Diver walked into the Dive Centre here in Cyprus as an Open Water Diver wishing to Dive Zenobia.

We explained that you must be a minimum of Advanced Open Water for us to take you on Zenobia and he expressed an interest in taking the Advanced Course.

On production of his certification cards, it appeared he didn't have any. Having done his training in Mexico, all he was given was a sheet of A4 paper stating "This Diver is certified to Open Water Training Level with the Diving Agencies; PADI, SSI, Naui, BSAC and CMAS" with an illegible instructor number at the bottom.

The gentleman in question was obviously devastated as he had paid a lot of money for something that wsn't real. He had even gone out and bought all his own equipment.

Unfortunately, there wasn't a lot we could do to help other than re-train and get him a proper certification card.

In resort, you should receive a Temporary Personal Identification Card (PIC) on completion of your training either in paper format from the dive centre or via email direct from the agency. These temporary cards last approximately 90 days, which should be plenty of time for your actual plastic card to come through the post to you.

If you do not receive the actual card, contact your instructor, who will be able to contact the Dive Agency direct to sort everything out.

Your certification card will usually have your picture on it too.

Supervision Ratios

Most Diving Agencies set ratios for the number of Student Divers that one instructor can teach at any given time. The maximum is usually 4 students per instructor but more students can join the group if the instructor has a Certified Diving Assistant.

Think about the quality of the training you will receive if you Learn to Scuba Dive in a big group like this. Sometimes, maybe it is better to pay a little more and get one to one training or just be in a small group of 2 divers to one instructor. Surely, this is better value for money!

So, there you have my guidelines for a Beginner's Diving Course. Regardless of which agency you decide to learn Scuba with, bear these tips in mind and know what you should be getting for your money and your Diver Training can be the best investment you will make.

Narcotics of the Deep... a Rapturous Dive

We all learn about Nitrogen Narcosis from our very first Diving Courses, be that with PADI, BSAC SSI, Naui, CMAS or GUE. It is an important consideration for any dives that we make but how well is it really understood in the Diving world?

What is Nitrogen Narcosis?

A Greek word (ναρκωσις) narcosis is derived from "narke", which means " temporary decline in, or loss of senses and movement".

Essentially, it is an alteration of consciousness as a result of the gases in our breathing mixes acting under pressure and a mixture of Dalton's and Henry's laws.

For those of you that don't remember them, this is the science bit... concentrate!!! (sorry L'oreal)


Dalton's Law

Dalton's Law states that the total pressure exerted by the mixture of non-reactive gases is equal to the sum of the partial pressures of individual gases.

We use it mostly in diving to work out our Partial Pressure of Oxygen at a given depth or our END (equivalent Narcotic Depth) for trimix

Henry's Law

 Henry's Law States that at a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

This goes back to decompression theory and the fact that, in the most basic terms, as we go deeper and the ambient pressure increases, more of the inert gas that we breathe dissolves in the body to balance the pressures of gases in the body with the surrounding pressures outside.

How does that work then?

Very interesting, you say! I remember those laws now but what does that have to do with Nitrogen Narcosis?

Well, let's look at what we believe to be the history and mechanics of Narcosis first.

Narcosis was first described back in 1834 by Victor T Junod, who was a French Researcher. His description referred to symptoms of intoxication being present and he surmised this was due to the increased ambient pressure increasing the blood flow in the body, which stimulated the nerve centres.

There were a few more theories over the years and much of our knowledge of Narcosis today is based on the study of anesthetics. The best theory we have for Nitrogen Narcosis at the moment is the Meyer-Overton Rule.

Around 1900, Meyer and Overton (independently) observed the potency of general anesthetic gases by testing their solubility in a simple organic solvent. They used Olive Oil as the organic Solvent, which represents the lipid bilayer found in our bodies, which make up the cell membranes of almost all living organisms and viruses.

Inert gas dissolves into the nerve cells lipid bilayer (Henry's Law) and causes narcosis by altering the nerve transmission in many diffuse areas of the brain resulting in symptoms described as; Euphoria, Over Confidence, Anxiety, Loss of Judgement and/or Paranoia.

We Diving instructors often teach our students about Narcosis by describing the "Martini Effect". This is a comparison between the way we act as we go deeper underwater and the way we act when we consume alcohol. Essentially, for every 10m we descend, it is likened to drinking one martini.



Even Jacques Yves Cousteau famously called it the Raptures of the Deep!!



Nitrogen Narcosis is a depth related problem. As we go deeper, the ambient pressure increases and so does the partial pressure of our inert gas (Dalton's Law). Beyond 30m, where the partial pressure of Nitrogen (PPN2) is above 3.16ata, we usually can begin to feel these symptoms

Is it just Nitrogen that causes Narcosis?

As Divers, we don't just have to worry about Nitrogen causing Narcosis at depth. It is widely accepted that all breathing gases have a narcotic effect but to varying degrees. Below is a list comparing the solubility of some gases in the Organic Solvent. Remember the Bigger the number next to the gas the more soluble it is and the more potency it has for Narcosis

GAS	SOLUBILITY
Helium	0.045
Neon	0.300
Hydrogen	0.600
Nitrogen	1.000
Oxygen	1.700
Argon	2.300
Krypton	7.100
Carbon Dioxide	20.00
Xenon	25.60

As you can see, our two primary gases in the breathing mix; Nitrogen and Oxygen are similar in Narcotic Potency with Oxygen being slightly more Narcotic than Nitrogen.

So why don't we worry so much about Oxygen Narcosis?

It is believed that the Narcotic effect of Oxygen is actually lessened becasue our bodies metabolise it but, to be safe, we are taught to assume Nitrogen and Oxygen have the same Narcotic Potency.

The suprising Gas I think is Carbon Dioxide. With such high solubility in lipids, we can see why it is such a dangerous gas and how Hypercapnea can kill a Diver.

Carbon Dioxide causes increased blood flow to the brain and is therefore, believed to increase and augment the narcotic effect of the other Gases too. This is why it is dangerous to complete hard, strenuous activity while diving and Skip Breathing or Shallow Breathing is BAD!!!!

As you can see from the table, the least Narcotic breathing gas is Helium, which is why deeper divers tend to opt for a trimix containing lower percentages of Nitrogen and Oxygen and filling the gap with Helium.

Some agencies even advocate trimix within recreational limits. For example GUE (Global Underwater Explorers) suggest that below 30m, breathing mixes should contain helium for less narcosis and better Work of Breathing.

Prevention and Management

The full complexity of Narcosis is not yet fully understood. However, the mechanism and primary agents responsible seem sufficient at the moment for us to make good decisions with regards to the gases we should use at certain depths while diving.

Recognising symptoms can be difficult due to the impairment they cause. The most dangerous aspect of Narcosis is the loss of good judgement and decision making abilities. If not recognised, these can lead to drowning. Good job we have our buddy there to help us out then!!!

To prevent Narcosis, avoid deep diving, strenuous activity, being cold, stress and Carbon Dioxide retention. If you are diving deep, use the correct gas mixes for the depth and keep your Equivalent Narcotic Depth above 30m.

Should you feel the symptoms of Narcosis, simply ascend and you should feel the symptoms diminish, although I have read reports recently that they may not vanish altogether until hours after you have surfaced.



We just don't know!!

Narcosis seems to be another Diving Problem that we are still only just learning about. It is dependent on the individual Diver's susceptibility to Narcosis and their health on the day of the Dive and many other variables that we just do not know enough about.

Be prudent, be conservative with your dives...

and if Nemo looks like he needs your reg more than you do, you are probably narked!!!