Suspension Trauma
WHAT YOU MUST KNOW TO SURVIVE IN A TREESTAND
By Dr. Norman Wood, 2009
Part 1
 |
Darrel Smith, Former WV Conservation |
Most hunters are not aware of the term Suspension Trauma, let alone the fact that you can die quickly in a safety harness from this killer. Most hunters feel that as long as they are wearing a full body safety harness and fall out of their treestand they will be fine, and most of the time you are. But if you fall and are unable to recover to a standing position, you can die in as little as 5 to 30 minutes. NASA studies have shown their personnel becoming unconscious in as little as 4 minutes while suspended in a harness and death will shortly follow unconsciousness. You must always use your full body harness correctly or it could cost you dearly.
This past year there were several hunters found dead hanging in their safety systems, two in one week in Ohio. On October 27, 2008 a 48 year old man in Portage County was found deceased hanging about 25 feet from the ground and on November 2, 2008 a 35 year old man in Carroll County was found deceased hanging 20 feet from the ground. One of the victims had a cell phone with him. And that is the point; you may not even have time to use a cell phone if you are ever caught suspended from your treestand.
In the industrial workplace, the prompt response time for emergency personnel to reach a suspended worker is approximately six (6) minutes. If you are able to contact someone do you think they could be there in 6 minutes? If you currently own a full body safety harness, take a good look at the warning labels. You will probably find one that says "PROLONGED HARNESS SUSPENSION CAN BE FATAL". And the manufactures are serious; everyone needs to be aware of suspension trauma and how it can harm you.
Let me be absolutely clear, everyone should ALWAYS wear a full body safety harness whenever in a treestand; it can save your life. You should be connected to the tree from the time you leave the ground until the time you get back down. There are plenty of different harnesses, the Rescue One CDS (Controlled Descent System), Non-CDS harnesses with suspension relief straps, Ascend/Descend Safety Lines and Lineman's Ropes available on the market today to keep you safe, and you should always be using them correctly as instructed.
 |
Lineman's Rope in use |
Trust me you are not quicker than gravity. And if you fall like I did, your bones will break and you can be killed.
I believe it is time that we have state enforced mandatory full body safety harness laws. Some may complain at first, but the injuries avoided and the lives saved would be enormous let alone the savings in medical care. According to the Consumer Product Safety Commission 82 percent of reported treestand related injuries and fatalities are from not wearing any form of safety system at all. And although Suspension Trauma is a very deadly concern, many lives would be saved and countless injuries would be avoided by getting all hunters to wear a full body harness while in a treestand.
We have all either fallen or know of someone who has fallen. If we must wear blaze orange while deer hunting with a firearm and if we must have flotation devices in our boats to be safe, don't you think the greatest killer of them all should be addressed? We need to do a better job of keeping our loved ones safe and it is time for our state legislatures to do something about it.
In addition to this legislation, the reporting of hunting accidents need to be updated as well. Currently in most states if you are injured while using a treestand, it is reported as a hunting accident instead of a treestand related injury. We need to have accurate reporting of treestand injuries to know the full scope of the problem so they can be addressed. A lot of vital information is being missed.
Seat belts in vehicles have saved thousands of lives and we complained when the law mandated them. But as a former State Trooper, I never once unbuckled a dead person and I took over 40 dead bodies out of cars in eight years. None of the dead were ever wearing a seat belt. Treestand Safety Harnesses, like seat belts, are seldom thought of as necessary until they are needed.
 |
Harness tether easily seen anchored |
Treestand accidents happen and if it happens to you, you will wish to God that you were wearing a full body harness. As a doctor, I can tell you that if you fall more than 6 or 8 feet you can be seriously injured or killed, and most treestands are 2 or 3 times higher than that. For most people unless you skydive for a living, being in a treestand will be the most dangerous thing you will do all year, by far.
Enforcement of a mandatory full body safety harness law would be easy to accomplish by our Conservation Officers. If caught in a treestand without wearing a full body harness, you get a ticket. Even if the harness is under a coat the tether is still easily seen where it is attached to the tree. And it's not an additional expense on the hunters since if you already own a treestand you have already taken a full body harness out of the box. You are either wearing it or you have thrown it in the corner of the garage. Now you will need to wear it which will take you another 2-3 minutes to put on. In other words, there is absolutely no reason not to have mandatory full body harness legislation that will save lives and prevent crippled bodies.
Just the knowledge of this law being in effect will motivate the vast majority of hunters to wear a full body harness, which in turn will save countless tragedies from occurring and save an enormous amount of money on healthcare.
There is also something that you should NEVER use or wear and that is a single strap system as your ONLY means of fall arrest. In industry, this type of safety device has been outlawed for a very good reason; it can kill you quickly if you fall. I will explain how later.
Part 2
So let's see how suspension trauma can be fatal. You first need to know a little about how your blood circulation works. The heart is nothing more than a living mechanical pump; to force blood out it must have a steady supply of blood coming in. The less blood returning to the heart the lower the blood pressure drops. Blood returns to the heart by the veins from the entire body. The blood then goes through the 1st half of the heart to the lungs to pick up oxygen and then back to the 2nd half of the heart where it is pumped back out to the body through the arteries.
As the blood leaves the heart it has significant pressure from the pumping action. But when the blood starts to return to the heart, the pressure is very low, it just seeps. This is because the blood has gone from the large arteries down to the microscopic capillaries and back to the veins. It is like putting a garden hose up against a large sponge. The water just seeps through and has very little pressure behind it.
When you are wearing a full body harness, like you always should, and if you fall from your treestand you will first be thankful that you're not lying on the ground either dead or busted up. But you only have a few minutes to get back to your feet. You can start feeling the effects of suspension trauma very quickly, and this is why. Your body's weight is pushing down on your leg straps so hard that it is causing a tourniquet affect on the large veins in your legs. This pressure stops the blood in the legs from returning back up to your heart.
The powerful heart can pump the arterial blood down into your legs, but the low pressure venous blood can't get back up. And this is the bad news; this is called Blood Pooling and the legs can store up to half of your total blood volume. It is just like having a major blood loss of about half of your blood without it ever leaving the body. It is the same thing as cutting both of your wrists and loosing half of your blood, and you know how long you would live that way. The longer you hang in your harness the less and less blood there is to circulate through the heart and lungs to keep you alive. Meaning your blood pressure starts to drop the moment you start being suspended because the heart has less and less blood to pump. Now the heart sensing this loss in volume increases its rate and pumps harder to try to keep the pressure up. It is killing you at an increasingly faster rate. The faster and harder your heart pumps, the more blood that goes into your legs where it pools, unable to return to the circulation.
You are now in a rapid downward spiral to death. But the body has a safety mechanism if this happens. It is called fainting. If the body has a significant drop in blood pressure you pass out because of the lack of oxygen to the brain. You fall to the ground and lay in a horizontal position and the blood returns to your heart and brain and you wake up. The bad news for you is that your harness is keeping you in the worse possible position if this happens; it keeps you in a vertical position. If you cannot get back to a standing position either back on your stand, on the ground or on a suspension relief strap to get the pressure off of your legs so the blood starts circulating again, you will become a suspension trauma victim pretty quick. It is only a matter of time and you will never know how much time you have.
So while you're hanging in your harness, your blood pressure is dropping by the second. There is less and less circulating blood to your heart and brain so there is less oxygen to keep you alive. You will begin to feel really bad and your heart will be pounding out of your chest as it pumps harder and harder trying to keep the pressure up. In just a couple of minutes the pain from the leg straps cutting into your groin will be unbearable. Your lower legs will go numb and your breathing will become rapid and more and more difficult as you struggle to stay alive.
You will be exhausted and dying, and without the right equipment on you, there is nothing you can do to stop it. As the blood pressure and oxygen reach a critical low level you pass out thinking of your loved ones. After becoming unconscious the heart will continue to pump as hard as it can in a futile attempt to live. As the blood pressure and oxygen level continues to drop, your brain experiences oxygen starvation and is forever damaged.
Your heart then experiences oxygen starvation and since it cannot adequately pump any longer, slows and finally stops altogether when it experiences a massive global myocardial infarction or heart attack when it runs out of oxygen.
In just a very few minutes, you have gone from having a great time being back in the woods doing what you love, to being killed while hanging in your safety harness. Your family, friends or the emergency personnel will find your lifeless body and lower it to the ground. The loss to your family will be insurmountable, a horrific tragedy that could have been prevented. And this exact scenario happens every year, several times.
There is one more vital piece of information that you must know and this has to do with the blood that has pooled in your legs. While hanging in your harness, the large amount of blood that has been pumped into your legs has changed considerably. In a couple of minutes all of the oxygen has been used up by the leg muscles and when that is gone, the muscle cells start what is called anaerobic metabolism or no oxygen metabolism to stay alive.
During anaerobic metabolism the muscles cells dump a large amount of acidic by-products that are toxic in large amounts back into the blood. At this same time since the blood is no longer moving micro blood clots can start forming in as little as 6 seconds. So what was once life sustaining blood has become a toxic sludge with clots and no oxygen.
And this is what you must remember. If you have been suspended in a harness for more than just a couple of minutes and if by some way you are able to perform a self rescue or if someone rescues you DO NOT LIE DOWN. If you do, all of that toxic sludge which was once blood will go racing back to your heart and you may die right there from a fatal cardiac arrest or a few days later from acute kidney or liver failure.
You need to stay upright for at least 30 to 40 minutes to allow the slow introduction of the pooled blood back into the circulation. If you must, sit down with your back up against a tree to keep your upper body elevated. Get back on your feet as soon as you can.
Part 3
WAYS TO STAY SAFE IN YOUR HARNESS
 |
Dr. Norman Wood Demonstrating the |
The best way to affect self rescue is with the new Rescue One CDS (Controlled Descent System) harness. It is the only full body harness that allows the user to safely lower themselves to the ground if a fall has occurred and recovery back to the stand is not possible. Suspension trauma injury or death is eliminated with the Rescue One CDS.
If you fall and are unable to recover back to your stand or to a standing position, utilization of the Rescue One CDS is quick and easy. A pouch on the right shoulder contains the emergency instructions and a brake handle strap. By pulling on the brake handle strap a pin is pulled and pressure is put on a Kevlar lined friction brake that allows controlled descent to the ground. As you ease up on the brake handle strap, the friction brake relaxes and allows the stored rope to be deployed out of its storage loops in the back of the harness.
The Rescue One CDS allows for a safe and controlled escape from a potential deadly situation. The Rescue One CDS weighs 6 pounds, is reusable and contains almost 30 feet of high strength line, plenty far enough for the vast majority of treestand hunters.
Most hunters already own a Non-CDS full body harness and it is extremely important that they know how to use them correctly and most importantly wear them. It is also important to know how a safety harness works and how it is constructed.
The American National Standards Institute (ANSI) developed fall arrest standards for industry and these are called Z359. These standards for harness testing ensure that the harness you trust your life to, can save it if you fall. In general industry almost all fall arrest equipment has been certified to ANSI Z359 standards.
The Treestand Manufacturing Association (TMA) made reference to and incorporated several sections of ANSI Z359 as their standards for fall arrest harnesses. These standards have been approved by the American Society of Testing and Materials (ASTM). Although the TMA has no legal authority to enforce these standards on any harness manufacture, they don't have too. The TMA is the recognized leader in treestand product safety. Most retailers, due to liability issues, won't sell a harness unless it has been certified to TMA standards.
Before a harness manufacture can use the TMA Approved Logo on their packaging, they must first be a member of TMA, have their package information and instructional DVD compliant with TMA standards and have the harness certified to TMA standards TMS 06-02. There are two main tests that a harness must pass to be certified to TMS 06-02. They are TMS 7.1 Performance Test and TMS 8.1 Dynamic Strength Test.
The TMS 8.1 Dynamic Strength Test is when the harness is attached to a mannequin, usually 300 pounds or more and dropped 2 times the lanyard/tether length. The test is passed if the harness prevents the mannequin from coming into contact with the ground.
The TMS 7.1 Performance Test is when the harness is attached to a 220 pound mannequin and dropped 2 times the lanyard/tether length. The Maximum Arrest Force or the maximum weight generated during its stop must not be more than 1,800 pounds. And the Total Deceleration Distance or the total increased length to the lanyard/tether must not be more than 42 inches.
For a harness with a webbing lanyard/tether it must have tear-away sections to pass the Maximum Arrest Force test or generate less than 1,800 pounds when it stops. If a harness had a straight webbing lanyard/tether it would generate around a 1000 pounds more than allowed. So a harness with a webbing lanyard/tether must have these tear-away sections to absorb energy. But these same sections can cause a problem that you need to be aware of.
 |
Harness Tether with Three Tear-Away Sections |
Every webbing lanyard/tether will have from 3 to 5 such tear-away sections. Each one of these sections will add around 3 inches to the length of the lanyard/tether if you fall. As they are intended to do, these tear-away sections will pull apart during a fall to absorb the energy.
So you can drop another 9 to 15 inches more than your starting lanyard/tether length. And with the other give and stretch that your harness will do when you put your entire body weight in it, which is around 5 more inches, you can drop 15 to 20 inches farther than your beginning lanyard/tether length if you fall from your treestand.
If you fall off of your stand onto the side of the tree away from your steps, if you are wearing heavy clothes and boots because it is cold, if you are not in the best shape, you may have just dropped down far enough where you cannot get back up. And most people who drop below their waist level with the stand base will not be able to get back up.
To see how difficult it is to get back onto your stand, you should place it just a few feet off of the ground, put on your hunting clothes and boots, and with another person there to help you if you need it, attach your harness to the tree where it will allow you to hang about waist height with your stand base and see if you can recover to a standing position. You will be surprised to see how difficult it really is.
So to prevent this from happening, it is vital that you attach your harness lanyard/tether up the tree as far as you can reach while standing on your stand. It must be at least top of head high or higher if you can reach to do it. Your lanyard/tether must be tight when you are seated. This will help ensure that if you do fall, and your lanyard/tether does lengthen, which it will, you can still hopefully get back up onto your stand.
And never use a single strap safety harness by itself as your sole means of fall arrest. These devices are killers. If you fall off of your stand, your full weight will be on the strap that goes around your waist. What this causes is an inability to breath. You can breathe out but you cannot breathe in because the strap is pushing your stomach up against your diaphragm preventing you from taking in another breathe. If you are not back up on your stand in a minute or two, someone will probably find you hanging there deceased.
Scientific studies on Suspension Trauma were conducted by the U. S. Air Force with human volunteers using fall protection devices. The following are the results of those studies showing the approximate survival times for the different fall protection devices:
SURVIVAL TIMES
| Device | Average Time | Range of Times |
|---|---|---|
Single Strap |
1 ½ |
Approx ½ to 4 ½ minutes |
Chest Harness |
5 ½ minutes |
Approx 1 to 13 minutes |
Full Body Harness (Non-CDS Type) |
14 ½ minutes |
Approx 5 to 30 minutes |
As you can see, you do not have a lot of time. That being said, you will likely have zero survival time if you fall and are not wearing anything. Although survival time can depend on your physical condition while suspended, EVERYONE will experience suspension trauma eventually. The only quick solutions for self rescue from this deadly situation is either getting back on your stand or to the ground by using a Rescue One CDS harness.
Part 4
Most harness manufactures are now providing, and TMA requires it starting in 2009, that a Suspension Relief Strap (SRS) be available with each Non-CDS harness. A Suspension Relief Strap will not let you self rescue to the ground, but it can buy you some time. Never use a Non-CDS harness without a Suspension Relief Strap. It is best if it is already attached to the harness so you cannot leave it at home and you cannot drop it if needed in an emergency.
The SRS is usually a section of 1 inch nylon webbing with about 2000 pound strength. The purpose for the SRS is to provide a way to stand up in your harness if you have fallen and you cannot recover to a standing position. By standing on the SRS that is attached to your harness, it lessens the pressure that the leg straps are placing on your groin and allows for blood to begin circulating back up to the heart.
 |
Suspension Relief Strap |
Depending on the Non-CDS harness make and model, the SRS attaches at one or two places on the harness to create a loop for your foot or feet. If you have fallen and cannot recover to a standing position, it is extremely important not to wait to use the Suspension Relief Strap. It can prolong your life and you should be pulling it out as soon as you realize that you cannot get back up to your stand. The bottom of the attached SRS must be above your feet so when you stand up in it, the harness leg straps loosen enough so the pressure on your legs and groin is greatly reduced.
One more important thing about the circulation in your legs, since the venous blood returning back up your legs has very little pressure behind it, the body had to have a way of moving it up against gravity. It accomplishes this by one-way valves in the veins and by the muscles squeezing the veins during movement. So it is the muscles moving that creates the pressure squeeze on the veins and since there are one-way valves the blood can only go in one direction which is back to the heart.
So it is vitally important if you are using a Non-CDS harness and have to use a Suspension Relief Strap in an emergency situation, you MUST keep your legs moving to get the blood back up to the heart. Do this by tightening and releasing the muscles, isometrics, in one leg and then the other. You don't have to do this so rapidly that it wears you out, just keep them moving between short rest periods. This will buy you some time, but no one knows just how much time that is. If you are unfortunate enough to have fallen and you find yourself suspended in a Non-CDS harness and you do not have a Suspension Relief Strap you MUST keep your legs moving the best you can for any chance of survival.
It is now after you are standing in your Suspension Relief Strap that you need to use a cell phone if available, call for help, yell or blow a whistle. But pace yourself, you may be in for a long night and hopefully you told someone where you were hunting. Remember, if you stop moving your legs, your chance of dying increases.
So make sure before you ever go into your treestand that you are wearing a Rescue One CDS harness or a Non-CDS full body harness with a suspension relief strap. Use an Ascend/Descend Safety Line or Lineman's Rope to get into and out of your stand. Once on your stand make sure that your harness lanyard/tether attachment point is up as high as you can reach. Your tether must be tight when seated. Always let someone know where you are hunting. And always carry a whistle or cell phone on you and not in a fanny pack that you hang up.
Don't take the chance of falling or of becoming a suspension trauma victim. They are both ruthless killers as many of our fellow hunters have found out. Do not let the message of your tragic death be delivered to your loved ones.
Great Hunting and Be Safe!
Dr. Norman Wood
Rt 1 Box 259F
Keyser, WV 26726
877-683-7678
Bio of Dr. Norman Wood
Dr. Wood grew up hunting and fishing in his home state of West Virginia. A former West Virginia State Trooper and Special Agent, Dr. Wood decided to attend medical school in 1992 after 16 years in law enforcement. In 1998 during his residency training at Ohio Valley Medical Center, he fell 20 feet out of a tree. He broke his pelvis in two places and his left hand. He was not wearing a fall arrest harness. As Dr. Wood states, "when you cannot walk for four months it gives you a lot of time to think".
During his recovery and up to the present time, Dr. Wood has been working on different safety products that make treestand hunting safer. He formed Mountaineer Sports LLC in 2007 and started marketing the Tree Stand Safety Belt. Dr. Wood joined the Treestand Manufacturing Association in 2009.
This past year, Dr. Wood finished his long term project, The Rescue One CDS (Controlled Descent System), a new revolutionary full body safety harness that eliminates serious injury or death from suspension trauma. The Rescue One CDS allows the user to safely and quickly lower themselves to the ground if a fall has occurred and recovery back to a standing position is not possible.
The Rescue One CDS, Tree Stand Safety Belt and other treestand safety products are available from Mountaineer Sports at www.mountaineer-sports.com.
Dr. Wood owns and operates three Urgent Care Clinics. They are located near Cumberland Maryland, Oakland Maryland, and Capon Bridge West Virginia.
References
- Holdcraft, Richard. SAFETY HARNESSES: Self-Recovery/Self-Rescue. 2004.
- Seddon, Paul. Harness suspension: review and evaluation of existing information. Health and Safety Executive, Research Report 451/2002.
- Feldstein, Joseph. ANSI/ASSE Z359 Fall Protection Code. Professional Safety, September 2007.
- Weems, Bill and Bishop, Phil. Will Your Safety Harness Kill You? Occupational Health and Safety. 27(3):86-90, March, 2003.
- U. S. Consumer Product Safety Commission, Washington, DC