Saturday, May 26, 2018

The Controlled Emergency Swimming Ascent (CESA) and why the way you learned it might not work

In the article, How to Preform the Controlled Emergency Swimming Ascent (CESA), the author describes how a diver that runs out of air would safely get to the surface. Interestingly, this instructor is not only a PADI Scuba Instructor, but a TDI Full Cave Instructor. This is particularly interesting because as a certified cave diver myself, one of the most important skills required prior to taking any overhead environment course is good buoyancy. As a cave diver, she should know that the new diver is very likely to need a lot of work on their buoyancy as well as is very likely to not practice skills after certification. Additionally, buddy teams, gas management, and communication are not only tenets of any technical diving specialty but are skills every recreational diver should practice on every dive.

"You are in your own world, calm, relaxed and . . . sluurrrp, out of air! Where's your buddy? No, really, where's your buddy? You look for your dive companion and his alternate air source and realize that he is nowhere near you."

NO! Sorry, but there are no lost buddies while scuba diving. There are true accidents and separation and then there are teams that put safety on the shelf prior to every dive. Staying with your buddy is at worst keeping your hand on them in zero visibility or at best diving side-by-side. When divers get separated, one or both of them failed to communicate their intention to stop, need to pause, or didn't keep their "eyes on the road." When I teach my open water course, I emphasize how important staying with one's buddy is by illustrating incentive in this manner. Offer an average teenager a quarter to do a job and find that it is never taken, done poorly, or even not completed. Offer three $100 bills with the caveat that the work has to be done perfectly and most will complete the work eagerly, with attention to details, and possibly even early. There are those that are not motivated anything, but very often when there is an incentive, and $300 is a pretty good incentive, one's goals change! If you don't want to lose your dive buddy, you do not!
"He does this by swimming slowly to the surface while exhaling and deflating his buoyancy compensator. Every certified diver learns the C.E.S.A. in his Open Water Certification Course, but most divers forget the skill because it seems complicated and is not practiced regularly."
One definitely wants to swim to the surface and if possible, at the industry standard of 30ft per minute, however the last I heard was that PADI states that 60ft per minute is an acceptable ascent rate. For whatever their opinion on the matter is, all other certification agencies as well as the US Navy have adopted 30ft per minute because of the preponderance of evidence based ultrasounds that show that bubble formation occurs the most at ascent rates faster than 30ft per minute and at all depths! 

Deflating the BCD is a precarious procedure as well. If one assumes that the new diver might be over-weighted, and they often are, then letting air out of the BCD during ascent might actually cause the diver to stop and descend -- fall back to the depth they came from or worse, deeper. When properly weighted, an ascent should be slow enough that extending one's fins against the water column is enough to slow the diver on their ascent. This isn't considering dropping one's weights at this time either. Releasing air from the BCD is also very likely to be the last thing an out-of-air diver will be thinking about. In fact, just keeping a steady and consistent kicking motion is a greater concern. Getting to the surface is paramount! Getting to the surface and subsequently getting bent is the risk a diver faces however never getting to the surface is a greater risk.

The procedure is not complicated but it is dangerous when performed incorrectly. Because the skill is facilitated by a scuba instructor under controlled conditions, it ultimately becomes a skill that cannot be practiced. Not only is the danger of an over-expansion injury real, but a fast ascent could lead to an "undeserved hit," getting bent when not expecting to or as a result of not doing anything wrong during the dive. Decompression sickness is always a risk when diving. There is no way to prevent it, only minimize the potential risks of it occurring.
"The Controlled Emergency Swimming Ascent (C.E.S.A.) can be a dangerous skill to practice. Do not practice swimming vertically towards the surface without a certified scuba instructor present."
LOL. Didn't I just say that? How does this sound to the student? "Here is how you save your life if you run out of air, but don't practice it or you could die!" This is exactly why students fail to continue practicing their skills after certification, fail to dive often and regularly to keep skill competence high, and forget how to do a majority of skills they learned (hopefully learned) during certification. Partner that with shops and instructors that offer two hour refresher courses in the pool to divers who have taken years off between dives, and it should actually be expected that students will get worse after the completion of their programs. Doesn't it make sense to have a skill that the diver can safely practice with limited risk that keeps their skills sharp? Of course it does.
"In fact, this is precisely the reason that the C.E.S.A should be practiced periodically..."
This seems rather contradictory to tell the student how dangerous the CESA is and then in the next paragraph to tell the student to practice it periodically. Some students only get the bare minimum already. Their job after certification is to practice the skills they learned so that their confidence builds, competency grows, and risks are reduced. Most programs fall short of everything needed during an emergency. Technical divers plan via a processes called, "accident analysis." They plan for emergencies to happen and prepare for them before each dive. Recreation divers plan for accidents during open water certification diving. 

First, recreational dive instructors do not put enough emphasis on the CESA. When it is performed, I see students floating on the surface while the instructor takes one at a time down to 20ft to perform the skill until everyone has had a chance to do it. It is more likely that the student is going to remember floating on the surface of the water waiting their turn and wondering how this skill is useful. Place them in the Puget Sound, floating on the surface of 50 degree water, and the CESA is the last thing they'll remember. When you practice these skills in these conditions, the reality is that you will never experience them this way in real life. An accident or emergency is never going to happen in this manner:
  1. waiting your turn
  2. descending down a float line
  3. kneeling or standing on the floor of the body of water you're in
  4. getting ready to perform the skill
  5. the instructor asking if they are ready
  6. the student taking a large breath
  7. the student and instructor swimming to the surface while exhaling
I'll explain these steps and problems with them shortly...
"To practice the C.E.S.A. safely on your own, select a shallow water dive site (such as a swimming pool) with sufficient space to allow you to swim horizontally at least thirty feet. Start thirty feet (or more) from a wall or other visible marker and practice swimming toward that “goal” as if it were the surface ​without removing your regulator from your mouth. By swimming horizontally, a diver eliminates the risks associated with pressure changes such as pulmonary barotrauma and decompression sickness. As long as he keeps his regulator in his mouth, a diver has no risk of drowning. You will practice the skill exactly as you would vertically. You are just turning the whole exercise on its side."
This example of how to safely practice a CESA is not only laughable but practicing in these conditions will not teach the student how to do the skill. Fireman practice on real fires; police are partnered with supervisors for real-life and face-to-face policing; doctors and surgeons practice on real patients; truck drivers practice in real vehicles and on the road...  You get the picture.
"Before simulating a Controlled Emergency Swimming Ascent (C.E.S.A.), a diver should relax and make himself neutrally buoyant. (A good way to obtain neutral buoyancy is using a skill called the fin pivot.) Neutral buoyancy is an important step because a diver will not be able to swim freely if he is sinking down and hitting the floor. He will have similar problems if he is fighting positive buoyancy and floating up. In a real diving emergency, a diver would begin the C.E.S.A. neutrally buoyant, so the practice scenario will be most realistic and beneficial if a diver begins the exercise that way."
Here in lies the problem with the CESA and why this procedure will not work. New students are never neutrally buoyant! They never stop swimming and when the do, they sink like a rock. Those few that are actually positive and are swimming so they don't ascend usually fail to keep this up and end up on the surface. Losing one's buddy is the bigger issue but we'll leave that discussion for another time.

When my students first get into the water, I teach them to be negative, stop swimming, put a finger or two on the ocean floor, and then add air to their BCD or drysuit and get neutral before proceeding. A new diver doesn't have the ability to get neutral while moving. That is the long-term practice that is just not present in the beginning. Slowing down or stopping does something else that is very important. It gets the diver to work on breathing! Neutral buoyancy is actually pretty easy. Add enough air in until you neither float nor sink. It's the diver breathing, flailing, moving, and possibly equipment position that effects one's position in the water. Coming from a cave diving instructor, Natalie should know this. A cave diver must maintain a constant air consumption rate or they cannot plan to complete their full dive. Cave divers follow the "rule-of-thirds." One third of your gas in, one third out, and one third for reserve. Changing air consumption changes the length of your dive -- it shortens it! Breathing to control buoyancy is an advanced technique.

Similarly, it takes a few seconds for every breath in and out to effect one's position in the water column. A cave diver cannot be ascending and descending on every breath. They'd sometimes be on the ceiling or cave floor, each with potentially fatal consequences. Put that diver in a rebreather, and neutral buoyancy comes from ones equipment, wing, drysuit, but never from breathing -- gas volume in a rebreather never changes.

So, what happens to the student that stops swimming the moment they take a breath from their regulator and no air comes out? They drop to the ocean floor. What happens when they hit the ocean floor? If they are over-weighted, another new diver issue, they try to swim to the surface and get nowhere. If they are at any great depths, a compressed wetsuit in a cold-water environment could mean that the student could be 10, 15, 20 or more pounds heavy. They didn't start out this way but if you remember Boyle's Law, that wetsuit compresses as you descend. While the diver would have added some air to their BCD during the dive, if they never stop swimming, how would they know how negative they really are?

What should the diver do if they ever find themselves negative, on the ocean floor, and out of air? Emergency Buoyant Ascent. Ditch your weight, push off the ocean floor, arch your back and when your chest starts rising toward the surface, start kicking in a smooth and steady fashion. One's left hand goes onto the inflator system, and not to let air out, but to have it available when the diver reaches the surface! Orally inflate that BCD! A speedy ascent is almost a given, but the statistics show that a very large number of divers found dead still have their weight belts in place, many still with air in their tanks, but never able to get to the surface. When they do get there, you must stay there. Not letting the air out of one's BCD and a fast ascent and possibly getting bent isn't guaranteed while staying on the ocean floor and asphyxiating or drowning is! There's a mention later on not ascending faster than one's slowest bubbles. Don't follow this rule. All bubbles and of any size ascend faster than 30ft per minute. 

With all this said, what happens if the diver is actually neutral. Swim, arch your back, lift the inflator above your head, and exhale all the way to the surface. It is in both of these first set of tasks that whether you are negative or neutral that swimming is probably the most important part of any swimming ascent! If one is ascending and exhaling, since the carbon dioxide is being exhaled, the urge to breath will not be there and since most exhalations still have enough oxygen to sustain life, your heart will still be delivering oxygen to your vital organs. Shallow water blackout is not likely either. Try it. Exhale, do not inhale... The feeling that emerges is the build up of CO2. The lack of oxygen only result in lack of coherence and then consciousness. Neither of those are going to happen in the next 30 seconds, minute, possibly even two. You may not like the feeling of CO2 building up, but oxygen goes further than you think on every breath!

The rest of Natalie's CESA example is on track except for the ascent rate of small bubbles. Practice is the key to surviving an out of air situation, but you have to be able to get into the right position to make it there. Here is what you can practice while you are diving. I'd recommend doing this below 30ft so that the five to six foot ascent (average height of a diver) doesn't affect your buoyancy so much that one continues to the surface. If your buddy wanders far enough away from you that sharing air is impractical, this opportunity will present a great time to simulate running out of air the moment you look for your dive buddy and they are not there. After completing the skill, if you can't find your dive buddy (as a slight ascent is the first part of the lost buddy procedure), ending your dive and making your way to the surface is usually the next thing you'll be doing. If you believe that you can start to swim to the surface if negative, watch this video. She is "climbing the invisible ladder." Try to take two steps before standing up will also demonstrate this...

EMERGENCY BUOYANT ASCENT (Practice -- Do Not Drop Weights)
  • If you are negative, you ALWAYS ditch your weights; tell yourself this as you are swimming around. Stop and see what happens. If you sink, and most divers do, if you run out of air, you MUST ditch your weights. Have you practiced this technique?
  • If you are near the ocean floor, push off the bottom; swim/arch/reach for the surface. If you've ditched your weights, you may not start moving to the surface if you are in a wetsuit and deep enough. 
  • As your chest rises, give a couple kicks to get yourself into a vertical position. Doing a five or six foot ascent at deeper than 30ft is very unlikely to result in a runaway. If it does, your buoyancy needs work!
  • With your left hand, find and hold onto the LP inflator system and look up. You want to make sure you are ascending, not going to swim into another diver or obstacle (i.e. boat, snorkelers, etc) 
  • Do all this while you have already exhaled. Inhaling and ascending should never be done. You have to practice regularly your exhalation technique which can easily be done when swimming up and over something you come across on your dive
  • Stop once vertical and return to diver position. If you started this simulation neutral, letting air out of your BCD or drysuit will be easy in a vertical position. If you were negative when you tried this exercise and never got vertical, you'll realize how difficult a swimming ascent can be and you'll know what to practice

EMERGENCY SWIMMING ASCENT (Practice -- Do Not Drop Weights)
  • If you are neutral, swim/arch/reach for the surface. Emphasize kicking hard, and bending your chest while looking up. Do not rely on using your hands in a water column. It is likely to not do anything
  • As your chest rises, give a couple kicks to get yourself into a vertical position. Getting vertical is the hardest part of a swimming ascent. Proper technique is crucial or you'll be climbing the invisible ladder
  • With your left hand, find and hold onto the LP inflator system and look up. If you actually were rocketing to the surface, then slowing yourself down is important but not more important that exhaling the entire way up or orally inflating your BCD once you get to the surface
  • Do all this while you have already exhaled. Taking a breath and then swimming to the surface is not possible when you are out of air. Don't have someone turn off your air so you can "feel what it's like." If you want to know what it's like, ask a friend if you can kick them in the testicles so he can know what it's like...
  • Stop once vertical and return to diver position. This is a practice exercise. However, if your dive is over, you and a dive buddy can try a slow and steady shallow and slow ascent using these skills. Get neutral and follow the procedures listed while slowly swimming to the surface and WHILE exhaling
  • I don't know why you would raise your right hand over your head, too, but if you have a weight belt on and haven't ditched your weight, it would be better for your right hand to be on your weight belt in the event that positive buoyancy wasn't achieved directly after the surface is reached and reach to ditch it!

The rest of the swimming ascents will be as usual. Exhaling slowly while slowly letting bubbles out, always keeping your airway open. Keep your head looking up and if you need to slow yourself, use your fins by extending them outwards against the water. Leave the regulator in your mouth and try taking a breath as expanding air may give you enough to take another breath. Pause if there is air, take that breath, then continue the exhalation and ascent. When you get to the surface, take the regulator out of your mouth and take a large breath. Exhale that into your BCD by using your LP inflator system. If you are diving in cold water and have thick gloves, you may have to use your second hand to push the deflate button hard enough to make sure it is open all the way so that you push all the air inside of the BCD. You'll have to practice this to see how easy or hard it is to orally inflate your BCD with only one hand and one finger. Things to consider, if your buddy is not by your side, that is a failure in teamwork that has to be addressed first after your dive is over! Without proper training as a "solo diver" your buddy is your first, best, and default safest way to get air, get to the surface, and not get hurt. As you swim around on your dives, visualize what you'll do, practice getting yourself vertical as quickly as possible and remember, long and smooth repeating kicks to the surface!

Here is a great video about the loss of oxygen. While it applies to flying, it represents how the lack of oxygen manifests itself differently than people think that it does. If you are exhaling CO2, you will not have the urge to breath. If you have a loss of oxygen which takes time, you lose coherence and eventually consciousness.

Want to see statistics reported by divers, including instructors, that show that a very large portion of divers complete training and fail to remain competent, click HERE. I can explain the details in greater detail if you need a better understanding of what they mean.

#scuba #scubadiving #outofair #controlledemergencyswimmingascent #outofair #cesa #padicesa #emergencybuoyantascent #emergencyswimmingascent 

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