If I know there’s a problem at work, I first should be capable of describing it. Any designated competent person (CP) soon becomes aware of this simple communication requirement. Over the past decade, the international fall-protection industry retroactively developed the suspension trauma (ST) relief strap (R-Strap) as a marketable add-on to their line of full body harnesses (FBH) that help prevent death and illness from a medical condition described as orthostatic intolerance. Every one of the R-straps on the market provide limited post-arrested fall (PAF) relief by reducing some of the physical conditions affecting the femoral veins in both legs. While a reasonable person would agree that any relief is better than none, many employers purchase these devices expecting to prevent their employees from succumbing to ST without any evidence as to their effectiveness in the field.
Once someone has experienced a successfully arrested fall in a Personal Fall Arrest System (PFAS) and is physically bound in a vertical, orthostatic posture by a standard PFAS, that system effectively reverses its life-saving function by:
- Allowing gravity to drain 5-6 liters of total blood volume into both legs within minutes;
- Setting double tourniquets by constricting leg straps at the groin to prevent return venal blood flow to the heart;
- Rapidly increasing heart rate, which can decrease pulse rate and blood pressure;
- Rupturing heart valves;
- Increasing numbness, paleness of skin and loss of vision and hearing.
Not everyone experiences all of these symptoms, nor do they always occur in the same sequence as variables like cardio-vascular condition, body weight, age, general health condition, and psychological make-up all play a role.
In two decades of training contractors in technical high-angle rope and confined space rescue techniques I’ve learned there are basically two options for most in a fully-deployed arrested fall — they’re either promptly rescued or faint. Upon becoming physically restrained by your harness in a head-up/feet-down (orthostatic) position, much less oxygen-rich blood reaches the heart, lungs and brain as gravity pulls it down into the veins of the legs and feet. As the total blood volume decreases, the brain issues a set of three survival commands: faint, fall — and equilibrate. As the harness-suspended victim initially faints, the brain sends a second and deeper command to lose consciousness. If the victim remains restrained, a third command to faint is typically issued. The unconscious victim will eventually die from brain hypoxia within 15 - 20 minutes of the arrested fall.
I’ve personally tested many models of R-straps that are primarily designed to reduce the garroting force of the leg straps on the venous blood vessels. In testing each of these R-straps, I was slowly hoisted in a tripod to experience orthostasis, without experiencing the slamming effect of an arrested fall. While each individual test exercise proved extremely strenuous, none of the R-straps proved 100 percent successful. Once the R-strap had been deployed and the leg strap(s) were adjusted in length, most of the body’s weight was applied by stepping into the stirrups or strap. In addition, the more slack generated in the relief strap, the greater the forward lean angle became. Regardless of the various strap designs and anchorage points, I discovered that my harness’s elastic leg straps were nevertheless difficult to loosen from the groin after having been stretched by my 210 lb. body weight. I can reasonably conclude they would likely be improbable to loosen after an actual 1,800 lb. terminal impact force (TIF). While some adjustable R-straps have a single strap for both feet, others have two separate stirrups. I found that my body weight applied in the single sling tended to force both legs together into the apex, making it more difficult to access my leg straps at the tourniquet in the groin. Any groin injury incurred in the initial slam impact of arrest would have been further exacerbated by this compound leg compression.
While the double stirrup design permitted me more access to loosen the leg straps from the pelvis, my body weight suspended at two contact points tended to compound my balance problem, as I hung forward and spun around. This eventually caused my leg straps to re-tighten. After multiple trials, I was quickly frustrated by my lack of physical control.
If you’ve never experienced an arrested fall in less than three seconds, let me assure you that your PAF suspension posture in a deployed harness at any height above grade is anything but “natural.” The brain becomes easily disoriented without any reference point even during the briefest suspension time. Depending on the free-fall distance, the nylon shoulder straps elongate several feet upon terminal impact at the dorsal D-ring, causing the body to come to rest in a 15-20º forward-lean angle.
This posture combined with chest strap constriction may increase chest compression, significantly restricting the heart and lungs. While stepping into an R-strap is intended to take a portion of the body’s weight off of the entire harness webbing system, it may not necessarily release the bilateral tourniquets on your upper thighs. Both the single strap and double stirrup designs of R-straps each require a high degree of concentration and physical effort to control after a fall. As we’ve all heard so often – practice makes perfect. In order to clear the anterior pelvis and avoid the ligaments of each hip joint, the femoral veins and arteries become sub-cutaneous precisely where the harness leg straps cross each inner thighs. The American Red Cross designates it as a pulse point and location for a battlefield triage leg tourniquet. With your body pitching, swinging and rotating, adjusting the leg straps to relieve the collapsed veins takes considerable endurance, patience and time.
As tension locks some connectors in place, too much slack may result in a dangerous accidental disconnection. Even volunteers in excellent physical condition were prone to heavy sweating, accelerated breathing rates and a spike in blood pressure within minutes of deploying the R-straps. Wearing heavy winter clothing may further compound this problem as during impact the leg straps can easily bury themselves deep in the folds of thermal wear. Any gloves will have to be immediately shed in order to work more effectively.
Many victims complain of hyperextended neck muscles after arrest, as most naturally endeavor to keep 10-plus pounds of head weight up with eyes horizontal. Subsequent swelling of distended muscles tends to further restrict blood flow to the brain through the carotid artery. This can accelerate the faint cycle.
Combined with the physical and psychological shock of any arrested fall, confusion and disorientation can reasonably prohibit total concentration on the self-rescue task at hand. Most rescue specialists agree that for this and many other reasons, self-rescue often becomes the least successful. I concluded that using the most effective R-strap in a non-impact suspension provided me a less than 40 percent relief factor from the myriad of conditions which seriously aggravate and may accelerate the onset of suspension trauma. I can only imagine this relief factor would be considerably less had I actually experienced a fully arrested fall.
Not only is orthostatic intolerance a problem during post-arrested fall, but so is OSHA’s maximum allowable 1,800 lb. TIF. The physical force encountered during an arrested fall using a shock-absorbing, elongation lanyard is equivalent to the force your body would experience from your seat belt upon running your vehicle head-on into a concrete bridge abutment at about 15 mph.
Beyond these physiological effects, psychological and systemic shock can also be problematic soon after an arrest. Panic and isolation can paralyze the suspended victim at the dire cost of valuable rescue time. These, in conjunction with pain, can all add up to real-time deterrents to vigorously exercising the “muscle pump” in the legs. The femoral vein runs either between muscle groups or muscles and bone. During leg exercise, this is meant to compress sluggish venal blood flow past dozens of vein valves and double leg garrotes every time a muscle is contracted and relaxed. Once leg exercises begin, they should continue until technical rescue arrives. Unfortunately, even though it could mean ultimate survival, the last thing a debilitated or injured PAF victim may want to do is painfully exercise in an R-strap. However, that was our only effective option to delay the deadly effects of orthostatic intolerance — until now.
The challenge for designers of the FreeTech Harness™ was to develop a comfortable, practical and affordable harness that would survive the initial fall arrest forces and then provide a simple and dependable load transfer system from vertical suspension to a seating posture. After two years of research, CMC and ROCO co-branded and marketed the device. In my professional opinion, it’ll undoubtedly set a significantly higher standard for all full-body harness designs in the near-future.
Now that this harness, with its patented Switchback System™ for repositioning, has become a reality, I believe that R-straps only slightly improve the chances of survival at the expense of extensive physical effort on the part of the restrained victim. Although it offers some potential relief, an R-strap does not actually change the victim’s vertical hang posture.
The advent of the FreeTech Harness™ provides a reasonable and improved alternative to the R-strap for workers who have experienced an arrested fall. A QP designing a PFAS now has the option to equip workers at height with a harness fully capable of providing an immediate point of refuge for anyone, anywhere, at any time. With its simple, two-step SwitchPoint System, anyone suitably trained who originally donned a FreeTech Harness™ can within seconds convert their posture from orthostatic restraint into a comfortable sit-position by grabbing the red tab of the SwitchPoint System release handle located in the pouch to the right of the harness. Next, firmly pull the red release strap out and away from the body. The dorsal release strap will feed out of the release buckle at the right hip. Your body weight will then automatically transfer to the secondary tether connected to your waist strap, dropping you quickly into the sit-position.
The repositioning function of the FreeTech Harness™ allows the victim to adjust any slack to the harness down to the leg straps with a minimal degree of effort. The awkward and disorienting forward hang position in R-straps is no longer a factor. The Switchpoint System allows the PAF victim to work on his/her self-rescue comfortably in a sit-position with a somewhat clearer mind and relaxed body. Even in practice, I immediately felt the mental and physical relief that the SwitchPoint System provided.
The FreeTech Harness’s revolutionary repositioning technology is, in my opinion, a game changer. When used according to the manufacturer’s instructions, it’s capable of eliminating many of the deaths and serious injuries roofing contractors suffer annually from arrested falls.