Nitrogen Narcosis

Besides the risk of decompression illness and other pressure related injuries, deep diving can bring divers in contact with another issue related to nitrogen: nitrogen narcosis, an euphoric, anesthetic effect. Although not a life-threatening condition, divers under the effect of nitrogen narcosis can fail in making good decisions based on good judgment.

What is Nitrogen Narcosis?

Besides the risk of decompression illness and other pressure related injuries, deep diving can bring divers in contact with another issue related to nitrogen: nitrogen narcosis, an euphoric, anesthetic effect. Although not a life-threatening condition, divers under the effect of nitrogen narcosis can fail in making good decisions based on good judgment.

Diver, Are you OK?

Nitrogen Narcosis effects are frequently compared to alcoholic effects. "Martini´s law" is a tongue-in-cheek reference that says that 30 mts/100 feet has the potential of one martini, with each 15 mts/50 feet thereafter equal to an added martini.

When breathing air, nitrogen narcosis develops with an increase in nitrogen partial pressure, typically at approximately 30 mts/100 feet.

What causes Nitrogen Narcosis?

The exact mechanism surrounding nitrogen narcosis is not fully understood, but almost any gas can cause anesthesia under high partial pressures. Theory suggests that nitrogen becomes dissolved in the lipids in neurons (nerve cells), which interferes with signal transmission from neuron to neuron.

Narcosis may cause a diver to feel drowsy, sleepy and may affect memory of the dive. The diver may feel falsely secure, exercise poor judgment and become uncoordinated. Some divers have reported hallucinations and giddiness.

How to avoid Nitrogen Narcosis

The effects of nitrogen narcosis recede quickly upon reaching shallower depths, with no after effects. The best way to prevent it is to avoid deep dives.

Individuals vary vary in their susceptibility to narcosis just as they vary in their susceptibility to any form of drug intoxication. At a given depth, some divers will be more impaired than others.

Source: Padi Encyclopedia of Recreational Diving pp 2-38, 2-39.

Selecting a BCD (Buoyancy Control Device)

A Buoyancy Control Device (BCD) is an essential part of dive equipment because it controls the three states of buoyancy while you dive: positive while at the surface, negative as you descend, and neutral while you explore the underwater realm.

Controlling the three states of buoyancy is important, specially positive and neutral.
Positive buoyancy will help you float effortlessly while at the surface, and neutral buoyancy will help you move freely without crushing or damaging the delicate marine life.

What types of BCDs are there available?

There are three styles of BCD: front mounted, back mounted and jacket style, being this last one the most commonly used nowadays.

Features to consider when purchasing a BCD

A good BCD must be capable to hold enough air to provide you with ample buoyancy at the surface. Also, it must have a large enough inflation / deflation hose that you can operate easily. Other important features include an over pressure release valve to prevent it from bursting when over inflated, and most important, it must include at least one emergency deflation valve to quickly release all the air in case of emergency.

How to maintain a BCD

BCD´s, as well as any other part of dive gear should be rinsed with fresh water after each use. Still, there are other two additional maintenance considerations: First, you should also rinse the inside of the bcd, and second, you should always store your BCD partially inflated.

As with every piece of your dive gear, BCD´s should be serviced at least once every year (or more often if you use it frequently) by a qualified technician.

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How to avoid Decompression Illness

Decompression illness, or DCI, is a term used to describe an illness that results from a reduction in the ambient pressure surrounding a body. There are two types of DCI: Decompression sickness, which is the result from bubbles growing in tissue causing local damage, and Arterial Gas Embolism, which 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.

What causes a diver to get Decompression Illness?

There are several reasons why a diver may get DCI, but among the most important ones we can list: rapid ascents, exceeding no decompression limits underwater, flying immediately after diving, being dehydrated, diving after an illness or fracture, deep diving etc.

Who can get DCI

Although every diver is susceptible to get DCI, there are some factors that increase the risk. Obesity and age are two of the most important ones. Divers with those characteristics should always dive under the supervision of their doctors.

How to avoid DCI?

1) Avoid deep dives. If you are a recreational diver the maximum recommended depth is 30 mts / 100 feet.

2) Check your Ascent Rate. Ascent at a rate that does not exceed 18 mts / 60 feet per minute

3) Stop before surfacing. Make a safety stop at the end of every dive

4) Stay within your limits. Do not make decompression dives without the proper training and equipment.

5) Know your tools and devices. Understand your dive tables and /or computer and never dive beyond their limits.

6) Avoid dehydration. Drink plenty of non-alcoholic fluids before, after and in between dives.

7) Be careful with medications. If you are taking prescription medications, seek your physician advice before diving.

8) Avoid flying inmediately. Wait at least 24 hours before flying.

In conclusion, understanding DCI is the best way to prevent it. Should you have any questions, ask your doctor, dive shop or instructor.