Gwyn Griffiths (GG) and Dan Wride (DW) have recently been in touch with their thoughts on suspension trauma. Here's what they wrote...
DW: The use of a harness is a common and often necessary part of climbing, caving and a range of industrial activites. After a fall, with or without loss of consciousness, a harness often allows an effective rescue to be made. However, as Roger Mortimer once wrote in the Journal of Wilderness and Environmental Medicine,
While remaining suspended and unconscious is preferable to falling, it has it's own risks and management issues...
Suspension trauma is typically seen in those individuals who spend a prolonged period of time hanging immobile in a harness. Hence, one of the alternative names for suspension trauma is harness hang syndrome. Indeed, there is some discussion as to whether "trauma" is really the correct term to use, because the consequences of the condition are not caused by a specific injury.
GG: Suspension Trauma? Harness Hang Syndrome? Suspension Syndrome? Orthostatic Intolerance? These terms all refer to the same problem - the inability of the human body to cope with being suspended in the vertical position. We'll use the term "suspension trauma" in this post - not because it's an accurate description of what's going on but because it's the most commonly used
DW: Suspension trauma is widely believed to be due to "skeletal muscle pump" failure. Normally, contracting muscles form a series of one way valves which help pump blood through the veins and back to the heart. When hanging motionless and vertical in a harness this is ability is lost. As a result, blood pools in the lower limbs and flow to the vital organs decreases. This patten has been confirmed in a recent study that monitored the cardiovascular responses of healthy volunteers suspended in a climbing harness for one hour. Pooling of blood was confirmed by an increase in superficial femoral vein diameter and a fall in lower limb oxygenation. However the study identified something else. Those who developed pre-syncopal symptoms and failed to complete the study, were found to experience a fall in heart rate and blood pressure prior to the onset of symptoms. Whilst the reasons for this are unclear, it would suggest that our understanding of suspension trauma pathophysiology may not be complete*.
It should also be noted that some waist harnesses exacerbate the process of venous pooling further by directly compressing the femoral veins and directly restricting the flow of blood back to the heart.
GG: Those involved in controlled experiments commonly report pre-syncopal symptoms such as lightheadedness, sweating, dizziness and visual disturbance. Paraesthesia and pain in the lower limbs are also commonly reported within minutes of exposure
DW: In normal circumstances, a fall in blood flow to the brain will result in syncope and more often than not, a fall to the floor. Strange as it may seem, this is helpful since the horizontal position improves venous return, promotes an increase in cardiac output and a return of consciousness. This does not occur when suspended upright. In this position, venous return and cardiac output continues to fall, with some literature suggesting that as much as 60% of the circulating volume can accumulate in the lower limbs. This blood quickly becomes starved of oxygen and swamped by breakdown products from damaged tissues. What little escapes into the wider circulation can cause damage to the vital organs.
Loss of consciousness in the upright position can also lead to to the patient's head falling forward and the onset of airway obstruction. This can quickly lead to hypoxia and cardiac arrest.
GG: Suspension trauma can be exacerbated by a number of pre-existing factors - dehydration, fatigue, heat exhaustion, hypothermia, trauma and chronic medical conditions such as diabetes mellitus, epilepsy and ischaemic heart disease. These may make it impossible for the victim to move, leaving them suspended in a vertical position and prone to developing suspension trauma
DW: The key to managing suspension trauma is to get the patient down from their suspended position as quickly as possible. If the patient is still able to co-operate, they should try to move their legs and raise them up in the horizontal position until they can be lowered.
GG: If the patient is conscious encourage them to move their legs in a rapid motion. Warn them that cramp-like pain is likely. This can be eased by asking them to push their feet against a solid object
DW: What to do once the patient has been lowered has been a source of controversy for many years. Studies on suspension trauma from the 70s and 80s suggested that patients rescued from upright suspension should be placed in a 'semi-recumbent' position rather than supine, because of the theoretical risk of overloading the right atrium with pooled, acidic blood and precipitating a cardiac arrest. This has been termed 'rescue death' in some circles. However, a comprehensive review by the Health and Safety Executive in 2009 found no evidence to suggest that supine positioning poses any increase in the risk of death. In fact, they suggested that not doing so could be 'deleterious' as concerns about 'rescue death' had sometimes led to deliberate delays in lowering patients to the ground and starting appropriate resuscitation.
GG: Harness design has little bearing on the prevention of suspension trauma since they are primarily designed to protect the spine and to hold the body upright no matter how it falls. A high-price harness will not prevent suspension trauma whilst suspended - however, it will make the first minutes a bit more comfortable! What matters is how to prevent the onward pathway of this life-threatening condition
DW: Once the patient has been laid in the supine position, normal ALS protocols should be followed, including ABCDE assessment and where indicated, the administration of supplemental oxygen and IV fluids. Those who have suffered a prolonged episode of suspension trauma are likely to have suffered extensive breakdown of damaged skeletal muscle. This process, commonly known as rhabdomyolysis, can lead to the release of toxic contents from damaged cells. In some instances, this can lead to an acute kidney injury and cardiac arrhythmias. Transport to a medical facility should be organised as quickly as possible.
GG: If victims are conscious and suspended in mid-air they will need to make a knee-loop to lift their legs and reduce venous pooling. Many practical and potentially life-saving techniques exist. Simple foot loops, either pre-sewn into a full body harness, or created using prusiks provide suspended patients a hold to step into, thus relieving the pressure on their legs and allowing their skeletal muscle pump to function
DW: As with any incident, prevention is better than cure. Whether in recreational or industrial settings, proper pre-planning, equipment, training, and safety awareness are crucial. Training to simulate a post-fall suspension rescue not only develops safe and effective rescue skills for team members, but also helps ensure that they have the necessary technique and understanding to perform self-rescue if needed. Repeated exposure to these situations also improves a rescue team’s ability to adapt to different situations.
Despite all that we have discussed, the body of evidence surrounding suspension trauma, outside of very controlled conditions, is limited. Most recommendations have been drawn from a small number of cases. However, what is clear is that prompt rescue of suspended individuals, combined with early assessment and treatment, is crucial to survival and reduced morbidity.
*An interview with the authors of this study will appear in this blog soon!
Thanks Gwyn and Dan!
Gwyn Griffiths serves as an advanced paramedic practitioner in the Welsh Ambulance Service. He specialises in mountain medicine and has worked in some of the highest mountain ranges in the world. He was a member of the Llanberis Mountain Rescue Team for more than thirty years. He hold a masters degree in advanced clinical practice from Bangor University, where he is now an associate lecturer in Advanced Clinical Practice.
Dan Wride is an F2 doctor with a passion for pre-hospital and emergency medicine who's aiming to go into ACCS training in 2023. His ultimate aim is to combine his loves of medicine, skiing and expeditions into his future career! He is a very keen skier, hiker and all-round lover of the outdoors. When he is not at work at the Royal Devon and Exeter Hospital, he can usually be found roaming the wilds of Dartmoor with his partner, or spending his Saturdays struggling on the hockey or cricket pitch!
A recent review of suspension trauma can be found here.