No More Nitrogen

  No More Nitrogen

Lesley Stein

I sit down, brainstorm, come up with an awesome topic, begin writing my first blog (a week before its due because I'm so stoked on my topic) and lo and behold a fellow grad student (Kaitlin Johnson) has written about the same topic and steals my thunder!  Kaitlin does a wonderful job also explaining nitrogen narcosis, however to switch things up a bit I will also be discussing decompression sickness.

SCUBA has become my greatest passion ever since I was certified.  I feel at peace underwater, free of stress, hearing only my breathing, and seeing only a world which fascinates me.   However this thrilling hobby can have serious repercussions.  Nitrogen narcosis and decompression sickness have always tripped me out because some of my closest friends have experienced them.  First lets dive into nitrogen narcosis.

What Is Nitrogen Narcosis?

Nitrogen narcosis is an altered state of mind caused by breathing nitrogen at a high partial pressure.  Partial pressure is the ratio of pressure exerted by one gas into a mixture of gasses.  In a diver's breathing tank the concentration of a gas, such as nitrogen, changes as the diver uses the gas to breathe and his/her change depth in the water.  Nitrogen narcosis occurs when a diver breathes a higher percentage of nitrogen due to increased depths.  Therefore, the deeper a diver descends and the higher percentage of gas creates a greater partial pressure....resulting in getting "narked" up.

What Are The Mechanisms Behind Narcosis?

The specific mechanisms of nitrogen narcosis are not well understood.  The most supported idea is that dissolved gas in nerve membranes causes short-term interference in nerve transmissions.  Increasing the amount of gas dissolved in nerve cell membranes can change the normal ion permeability of a neural cell's lipid bilayer.  The lipid bilayer may allow ions through that normally would not and potentially block others that naturally would pass therefore, allowing nitrogen into the bloodstream at high pressures.  

This shows as a diver descends the total pressure of gasses increase, in turn increasing each gas proportionally.

What Are The Effects Of Narcosis?

I have personally experienced getting "narked" up.  Prior to diving I was timed to find the solution to a simple PVC pipe puzzle.  The test consisted of connecting 8 pieces to fit a square.  On land it took me 8 seconds, however, once I was 95 feet under water and attempted the puzzle it took me one minute and 15 seconds.  I was experiencing slight nitrogen narcosis.  What did it feel like?  More like what didn't it feel like.  I just didn't really care about anything, I wasn't cold, I didn't care about a stupid little puzzle, I was feeling a little tipsy, and all I wanted to do was bob up and down based on my breathing.  Luckily this wasn't an extreme case of narcosis and my friends noticed my struggle with the puzzle and kept an eye on me until everyone completed the puzzle and surfaced together.  Other people have noticed effects such as lightheadedness, feeling drunk, loss of reasoning, over confidence, difficulty concentrating, decreased coordination, hallucinations, coma, or in some cases death.  The main way it can lead to death is by diving alone, experiencing narcosis, and not having the ability to mentally recognize it or have the “will power” to take correct action.  This can lead to staying under water longer than you have enough air for. That is one among many reasons why you should never dive alone.  

Ways To Reduce Narcosis/ Treatment

Several ways to reduce nitrogen narcosis symptoms are to be motivated to complete specific tasks, acclimate yourself multiple experiences of narcosis, or having a high tolerance of alcohol consumption.  Interestingly, it has been shown that a diver with a "high tolerance" of alcohol consumption has a higher tolerance to narcosis.  

A nickname for the effects of Nitrogen Narcosis is Martini's Law.  Meaning every 10 meters is equivalent to drinking one martini.  Therefore, in my case according to Martini's Law I had 3 martinis, which kind of makes sense...

The best method to treat narcosis is slowly ascending to shallower depths, keeping in mind decompression limits.  Which is a great segway to discuss decompression sickness.  

Decompression sickness

Often non-scuba divers (or also those that should not be diving) get nitrogen narcosis and decompression sickness confused with each other.  In reality the two are very different, nitrogen narcosis involves being at depth (usually 100ft or deeper) and is experienced during a dive, whereas decompression sickness involves how quickly a diver ascends to the surface and is expressed after a dive.  A diver can experience one condition during a dive or if extremely unfortunate both, but one is not dependent on the other. 

What Is Decompression Sickness?

Decompression Sickness (DCS) also called the "bends" is an illness caused by nitrogen being absorbed by and remaining in the blood and fatty tissues caused by ambient water pressure.  Bubbles from nitrogen grow in ones tissues and causes local damage.  DCS got the nickname the "bends"; by these bubbles forming in the spinal cord, which would cause inflation and could cause a person to develop arthritis, leading them to be bent over.  Normally when a diver ascends properly (no more than 30 feet per minute) the pressure around the diver decreases.  This allows nitrogen molecules out of the cells and into the tissues; they enter the bloodstream and are transported to the lungs to be released by exhaling.  However, DCS occurs when pressure around the body is released too quickly, in turn creating bubbles within the tissues.  Bubbles are created when large amounts of nitrogen molecules are released from cells; these molecules are attracted to one another creating a bubble.  The bubbles have surface tension which traps them in the lining of the tissue.

What Are The Symptoms?

Symptoms usually occur 30 minutes after a dive. 

• ·      Pain in joints, muscles, arms, legs, or torso
• ·      Inflammation
• ·      Itchy skin
• ·      Tingling
• ·      Shortness of breathe
• ·      Ringing in ears

What To Do When You Have DCS?

It depends on the degree of DCS; there is a Type 1 and a Type 2. Mild cases are Type 1and can be treated with an oxygen facemask and symptoms may simply go away.  Type 2 DCS is more severe and requires going into a hyperbaric chamber.  Type 1 is usually dealing with the peripheral nervous system, while Type 2 usually involves the central nervous system.  So what exactly is a hyperbaric chamber? 

A hyperbaric chamber is a large closed contain that people can walk in and out of that holds gases at a certain pressure.  The purpose of the chamber is to allow the diver to complete their safety stops.  Safety stops while scuba diving are meant to allow the nitrogen to come out of the tissues and back into the bloodstream.  The appropriate amount of pressure is applied along with pure oxygen.  The oxygen is taken up into the blood faster in the chamber, which helps repair cells.  The time spent in the chamber depends on the amount of nitrogen in one’s body, sometimes as long as 18 hours.  Overall, Scuba diving is an amazing hobby, but it is important to understand the dangers involved with breathing under water. 

Citations

Baddeley, A.D., J.W. Figueredo, J.W. Hawswell Curtis, and A.N. Williams. 1968. Nitrogen narcosis and performance under water. Ergonomics Vol. 11, Iss. 2.

Edmonds, C., B. Thomas, B. McKenzie, and J. Pennefather. 2012. Diving Medicine for SCUBA Divers Chapter 18.

Emmanuel Gemp and Jean-Eric Blatteau. 2010. Risk factors and treatment outcome in scuba divers with spinal cord decompression sickness. Journal of Critical Care, Volume 25, Issue 2, Pg 236-242.

Nadan M Petri and Dejan Andri. 2003. Differential Diagnostic Problems of Decompression Sickness- examples from specialist physicians' practices in diving medicine.  Archives of Medical Research, Volume 34, Issue 1. Pg 26-30.

Thalmann, E.D. 2004. Decompression Illness: What Is It and What Is The Treatment? DAN Divers Alert Network.

Rostain, J.C., N. Balon 2006. Recent neurochemical basis of inert gas narcosis and pressure effects. Undersea and Hyperbaric Medicine pg 197–204.