Redefining the Diagnosis and Treatment of Suspension Trauma

By Joseph J. Kolb, MA & Ellen L. Smith, MD, FACEP

On the night of Feb. 11, 2011, the San Diego County Sheriff's Department and the U.S. Border Patrol's Border, Search, Trauma and Rescue (BORSTAR) team were called out in response to a rock climber unresponsive in his harness, dangling some 200 ft. above ground. He was reported to be bouncing in and out of the flow of Mildred Falls, a large waterfall located near Julian, Calif., and a popular area for rock climbing, canyoneering and hiking.1

"With the information given from the pilots, and the length of time he was hanging in his harness, we all agreed it was a recovery at this point," said BORSTAR agent Noah Slack, who was involved in the man's rescue.

It appeared the man was trying to rappel to the bottom of the waterfall, which is close to 300 feet high, and ran out of rope. Once he realized his rope wasn't touching the bottom of the pitch, he attempted to ascend the rope using his Purcell Prusiks, but was now under the flow of the waterfall. He had rigged his anchors right next to the stream feeding the falls.

At first glance it looked like he wouldn't have been under the flow, but due to the terrain below, his rappel path deviated him into the waterfall. It looked like he was able to ascend 20–30 ft. from the bottom of the rope before stopping. He had on a typical seated climbing harness without a chest strap. He also had a small backpack on his back.

"The victim was deceased, and appeared to be folded over backwards," Slack said. "I assumed this from his position and the constant flow of water falling over him."

The autopsy revealed that the man's death, while accidental, was the result of mechanical asphyxia. Essentially, he'd succumbed to a respiratory and systemic collapse from hanging motionless for a prolonged period of time in his rock climbing harness.

A Rapid Cascade

Mechanical asphyxia is also referred to as suspension trauma, harness-induced pathology, orthostatic shock while suspended,2 harness suspension,3 suspension trauma cascade4 and orthostatic intolerance.5 It's a rare but potentially fatal condition affecting individuals engaged in occupations or activities that require the wearing of a pelvic harness, such as power line workers, cell phone tower installers, rock climbers, parachutists, and caving and rope rescue technicians.

Suspension injury and death from suspension trauma is a rapid cascade of events taking place over 6–30 minutes. Venous circulation in the lower extremities when suspended vertically causes sluggish blood return to the core. Lack of muscular contraction of the muscles of the legs due to confinement or fatigue worsens venous pooling. The core becomes relatively hypovolemic leading to cerebral hypoperfusion and low cardiac stroke volume. As the brain becomes more ischemic, fainting occurs in order to reach a horizontal state and return venous volume. The suspended patient faints without achieving a horizontal position. Fighting gravity, the head and neck may pitch forward causing a potential airway obstruction. The patient with an obstructed airway and hypotension has only minutes before cardiac arrest. Patients who are suspended may have also had deceleration trauma to the body with special concerns to the cervical spine leading to a more rapid decline. Figure 1, p. 50, illustrates how rapid a patient's condition can deteriorate if not given appropriate pre-rescue instructions.

Suspension trauma first emerged after the plight of 10 mountain climbers was presented by an Austrian group at the 1972 Second International Conference of Mountain Rescue Doctors. It was reported that of the 10 climbers who became trapped in a suspended position before rescue for durations ranging from 30 minutes to eight hours, two expired pre-rescue, three died almost immediately after rescue and five died over the course of the ensuing 11 days.4,6

Madsen reported a case where a soldier was instructed to mimic being unconscious while on a rope.7 When the instructor returned six minutes later with the rest of the troops, the suspended soldier was found dead.

For decades the treatment for suspension trauma suggested that conventional emergency care could actually be fatal to the patient. That premise has been contested in recent literature calling for a complete reversal of the acute treatment protocol.6

Ascertaining what form of shock results from prolonged vertical suspension has been debated. Published reports associate suspension trauma with distributive shock.8,9 Distributive shock is a hemodynamic process resulting in gross vasodilation as seen in inflammatory events such as anaphylaxis as well as septic shock. There's no vasodilation in suspension trauma; if anything, there's pooling secondary to the pull of gravity and absence of mechanical pumping of the muscles to maintain normal circulatory function associating the event with hypovolemic shock.

The cause of death in suspension trauma has also come under scrutiny and has had a direct impact on the rescue protocols that have been followed for more than 40 years. In much of the research subsequent to the 1972 Austrian report, there was a presumption that the primary cause of sudden cardiac arrest was associated with cardiac overload secondary to putting the victim immediately into the supine position. Recent findings refute this contention by asserting that the sudden cardiac arrest is associated with hypoxia and hyperkalemia from acidosis, shifting the treatment paradigm into a new direction.6

Mechanism of Injury

The undisputed cause of suspension trauma is from the body being in a motionless suspended vertical position, whether due to the individual working and not being attentive to their motionlessness, sustaining an injury which precludes movement, or, as in the case earlier, there was a problem with rope length or rigging that required attention but kept the climber motionless.

It was originally believed that the support harness the individual wore created a "tourniquet effect," compressing the lower extremity circulatory system, particularly the femoral vein, and causing sympathetic stress on circulation from the pain of a constrictive harness.2 Recent findings are more supportive of venous pooling from lack of muscular-induced venoconstriction that allow continued dependent venous stasis.6

Harness style and fit may be protective or counter protective in a suspension victim scenario. Some rock climbing harnesses have a non-adjustable thigh strap that may further impede venous return. Others may contain a chest strap, safely allowing multiple positions for the victim, including a horizontal position. Safety harnesses are typically classified as front and rear attached.4 The front attaching harnesses can have a waist attachment, which is commonly found in rock climbing, caving and mountaineering. The rear attaching harness may allow the worker freer use of hands, but a more difficult self rescue.

When considering any harness, the front attaching harness provides little pressure on the femoral vein and maintains the upper part of the legs in a semi-horizontal position, mitigating the pull of gravity on blood in the legs. When a victim can create a more horizontal leg position, they may be able to delay the suspension cascade. Harnesses with a rear attachment, or one that's higher on the sternum, may be harder to counterbalance in a horizontal position for the victim. The front attaching harness including a rope latched to a sternal ring and containing a rear attaching harness is required by OSHA as a fall arrest system for workers at heights above six feet.

The rear attaching apparatus is also found in parachutes. Individuals in these devices can succumb to the cascading effects of suspension trauma almost immediately because the lower limbs are in a suspended vertical position, increasing pressure on the femoral vein and nerve and exacerbating the gravitational pull on lower extremity blood flow.

Pathophysiology

Lower extremity venous circulation is exclusively dependent on muscle contraction. When suspended and immobile, a "cascading" event can occur almost immediately. Some of the more common causes of being rendered immobile include: injury, confusion, physical/emotional exhaustion, pain, hypoglycemia and muscle failure.4 What can't be ignored is prolonged working, observation, or even rescue efforts of an injured patient without the rescuer consciously moving the lower extremities.

Failure of the venous return circulation to be executed through muscle contraction can result in a relatively rapid accumulation of 20% of blood volume in the lower extremities. If not checked, this can increase to 60% with only a remote chance of survival. As blood volume pools it becomes acidic due to hypoxia and resultant anaerobic metabolism in muscle cells evolving into rhabdomyolysis. This death of muscle tissue causes a release of enzymes in the blood, an increase in myglobin release and hyperkalemia, all of which can lead to renal failure.

he onset of suspension trauma can occur in as little as three minutes but will rapidly cause a deterioration in the patient's condition and prognosis as time passes. Death can occur in as little as 10 minutes.

Early warning signs of suspension trauma include experiencing hot flashes, sweating, numbness in the legs, bradycardia, low blood pressure, nausea, dizziness, diaphoresis, and confusion secondary to cerebral hypoperfusion. The victim will also experience a change in heart rate or arrthymia. This is referred to as the pre-syncopal stage.10 Occurring in one in five victims within 10 minutes but typically after being suspended for an hour, this warning stage presents an opportunity, however brief, to call for help or get out of the harness and lay supine.10 The person may sense a need to go horizontal to mitigate the symptoms but can't due to an injury, technical issues involving the rope/harness/climbing gear, or they fainted. When the patient experiences syncope they can't protect the airway and succumb to mechanical asphyxia. This is especially relevant in the case of harnesses with a rear rope attachment, which encourages neck flexion in an unconscious patient.

Prehospital Care

First and foremost for the suspension trauma victim is to get them to the ground. This may include raising the patient above, lowering the patient below or placing them on a nearby ledge. A chest strap should be placed if the victim is injured or hanging more than a few minutes.

Rescuer safety is critical. Since many of these victims are in precarious positions and altitudes, a sound and efficient rope rescue strategy must be established that includes an estimated time on the rope to secure the victim and whether to raise or lower the victim to the ground. Given the time on the rope to stabilize the patient, rescuers must be cognizant not to suspend their legs motionless during the recue process.

Immediate access rescue either by EMS or by adjacent climbers may be the only means of preventing death in suspended climbers or fallen workers due to the short timeline. Shouts could be made to have the climber swing the legs like a child in a swing either together to get to a ledge or individually to pump the leg muscles. An additional cloth, towel, jacket, rope or etrier (aka a "standard aider") can be sent down the rope to be deployed as a leg rest. A simple backpack and rope can be made into a seat. Rescuers should consider the simple etrier, which is light, easy to carry and quick to deploy, and can give the victim a leg rest.

Rescuers can also position themselves adjacent to the victim to allow them to rest on their body. An immediate chest strap should be placed on the victim to prevent inadvertent leaning out of a sit harness during this process. A simple soft collar may be investigated in the future as a means of preventing mechanical asphyxia should the victim have a loss of consciousness.

The rescuer will often have both hands involved in regulating his own rope and gear at times, and keeping the victim's head from hyperflexing or hyperextending will be a simple assist to the rescuer. To use the etrier, the rescuer simply attaches it to the rescue rope above the victim and it deploys exactly as a rope ladder for foot holds. These holds can be for the victim's feet to allow a horizontal body position.

Once on a safe location with no capacity to fall, if the patient is conscious they should be encouraged to vigorously move their legs. Footholds or resting the feet against an adjoining structure can mitigate symptoms and provide the patient intermittent relief.

Until recently, studies suggested keeping the recovered unconscious patient in a semi-recumbent or even seated position to mitigate the flood of fluid and toxins into the heart that was hypothesized was the cause of death for the majority of victims. One treatment suggested keeping the victim in a seated position for at least 30 minutes.8 Recent findings, however, contradict this.6,7

One recommendation is to keep the unconscious patient in the semi-Fowler's position of keeping the upper body at a 30–40-degree angle, then slowly bringing them to a fully supine position in 30–45 minutes.10 Another is more specific, recommending that the conscious patient should be kept in a seated position for at least 45 minutes but a semi- or unconscious victim should be put in the supine position to return blood flow to the brain.4

Others see no reason to differentiate between levels of consciousness and what position to place the body in, advocating immediate supine positioning of the victim,6,7 asserting the cause of death is typically secondary to hypoxia and hyperkalemia, so rushing to keep the victim in a seated position is irrelevant.6

Assessment of airway and cardiac status should immediately follow, as should appropriate lifesaving measures, including field defibrillation, if indicated; high-flow oxygen; and fluid replacement to expand blood volume--alternating saline and half-saline with sodium bicarbonate added to counteract acidosis.6 An IV of calcium gluconate 10 mL of 10% solution can be given to combat hyperkalemia and stabilize cardiac rhythm.4 If a patient was suspended for longer than two hours they should immediately be transported to the closest trauma center, or to closest overall if the patient has no vital signs.

Conclusion

The authors argue for a revised definition of suspension trauma. Defining the malady as orthostatic shock may also be misleading. While a syncopal event typically ensues, it's rapidly self-corrected by elevating the lower extremities. A comparison can be drawn to a person fainting after sitting for a long period: Lowering the head to chest level allows the head to be perfused at a lower systemic BP, allowing venous return cautiously from the legs. When the individual passes out in a harness, syncope is instead a prelude to the catastrophic cascade of events. "Suspension shock" emerges as a more accurate definition for this disorder to be considered by the professional medical community.

In any event, the prevalence of suspension trauma may be more frequent than realized. Understanding the high risk populations in your community may be an initial step toward preparing for an event and knowing what to do when you arrive on scene. Look to see if there's any work being done on cell towers or phone lines. If your area is known for recreational events such as rock climbing, caving and parachuting, contact these organizations to ensure there is preventive education. Most importantly, be sure your agency's rope rescue team members are familiar with suspension trauma and how they can avoid becoming a casualty during the rescue process.

Joseph J. Kolb, MA, is a member of New Mexico Task Force 1 FEMA Urban Search and Rescue. He possesses a BA and MS from Adelphi University (N.Y.) in sports medicine.

Ellen L. Smith, MD, FACEP, is board certified in emergency medicine and has a practice in sports medicine in Montgomery County, Md. She's taught the Wilderness Medicine Field Course to over 600 medical providers and adventurers. Visit her website at www.wildmedmd.com.

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