Rescue planning and suspension intolerance

A fall arrest system that works perfectly leaves a worker hanging in a harness, sometimes many meters above the ground, sometimes against the face of a building, sometimes injured and sometimes unconscious. Getting them down quickly and safely is part of fall protection, not an optional extra. Every jurisdiction requires a rescue plan before work with fall arrest begins. This lesson explains why rescue is urgent, what suspension does to the body, and how to plan a rescue that will actually work on the day.

Why rescue is urgent

There are three reasons to plan for fast rescue. First, the fall itself may have injured the worker, through the arrest forces, a swing into a structure or contact with objects on the way down. Second, a worker hanging in a harness is exposed to the weather, to whatever caused the fall and sometimes to further hazards such as a moving machine or a fire. Third, motionless suspension in a harness can itself lead to fainting and, in some cases, death, a condition known as suspension intolerance, suspension trauma or orthostatic intolerance.

Suspension intolerance

When a person stands still for a long time, blood pools in the legs. Normally the leg muscles pump it back toward the heart as we move. A worker hanging in a harness, especially one who is still because they are injured, exhausted or unconscious, has the leg straps pressing on the thighs and little muscle activity in the legs. Blood pools in the legs, the return of blood to the heart falls, blood pressure drops and the brain receives less oxygen. The result can be fainting, and if the worker remains upright and suspended, the reduced blood flow can become dangerous.

OSHA's 2004 Safety and Health Information Bulletin on suspension trauma lists early symptoms that include light-headedness, dizziness, nausea, sweating, weakness, paleness, breathlessness, a racing heart and graying or loss of vision, with later signs including an unusually slow heart rate, low blood pressure and fainting. It cites research indicating that suspension in a fall arrest harness can lead to unconsciousness and death in less than 30 minutes. How quickly symptoms appear varies widely between people and situations: some people feel faint within minutes, others tolerate suspension much longer. Injury, dehydration, heat, cold, blood loss and heart or lung conditions all make things worse, and a poorly fitted harness makes things worse still.

Workers who remain conscious can slow the onset of symptoms by moving their legs, pushing against the structure, or standing in a trauma relief strap. Many harnesses now include trauma relief straps, small loops of webbing stored in pouches on the harness that the suspended worker can deploy and stand in. These buy time, but they are not a rescue. A worker who is unconscious cannot use them.

After the rescue

Older advice said that a rescued worker should be kept sitting up for 30 minutes rather than laid flat, because laying them down might suddenly return pooled blood to the heart. That advice was based on limited and largely theoretical evidence. A 2009 evidence review for the UK Health and Safety Executive found no good evidence to support it, and current first aid practice is to treat a rescued worker like any other casualty: check breathing and circulation, place an unconscious breathing casualty in the recovery position, provide standard first aid for injuries, and call emergency services. OSHA's bulletin similarly calls for standard trauma resuscitation and first aid. Every worker who has been suspended after a fall should be evaluated by a health care professional, because complications can develop later.

First aid for injuries from falls is covered in HSE-110 First Aid Awareness, and CPR in HSE-111.

What the law requires

OSHA requires employers to provide for prompt rescue of employees in the event of a fall, or to ensure that employees can rescue themselves, under 1926.502(d)(20) in construction and 1910.140(c)(21) in general industry. Prompt is not defined in minutes, but OSHA's guidance and the suspension trauma bulletin make clear that rescue must happen quickly, and simply calling 911 is not enough unless the employer has confirmed that the emergency service can reach and rescue a suspended worker in time. ANSI/ASSP Z359.2 requires a written rescue procedure as part of a managed fall protection program, and Z359.4 covers safety requirements for assisted rescue and self-rescue systems.

Types of rescue

Rescue options range from simple to complex. Choose the simplest one that will work for the situation, and plan a backup.

Self-rescue

A conscious, uninjured worker may be able to rescue themselves: climbing back onto the structure, climbing onto a ladder placed by a coworker, or lowering themselves with a self-rescue device built into the harness or lanyard. Self-rescue depends on the worker's condition, so it should never be the only plan.

Assisted rescue from the structure

Coworkers on the structure can rescue the fallen worker without anyone else going over the edge, using:

• a self-retracting device with integral rescue, which can be switched to raise or lower the suspended worker;
• a pre-rigged rescue system, such as a pulley system or a descent device attached to an anchor above the worker;
• a rescue pole to reach and connect a rescue line to the worker's harness.

These systems need trained users, regular practice and equipment that is on site and ready.

Rescue from below

An elevating work platform, scissor lift or boom lift can often reach a suspended worker quickly, if one is on site, has enough reach, and can get under the worker. Rescuers on the platform must use their own fall protection and must be able to take the weight of the casualty without overloading the platform. A ladder can sometimes be used for a conscious worker hanging a short distance above a floor. Rescue from below is often the fastest option on construction sites where lifts are already in use.

Technical rope rescue and emergency services

Some situations, such as rescue from towers, from the face of tall buildings or from inside structures, need a trained technical rescue team with rope rescue equipment. Some large employers have their own teams; others contract specialist rescue services. Public fire departments may have high-angle rescue teams, but not all do, and their response time may be too long. Before relying on emergency services as the plan, confirm that they can reach the site, have the equipment and training for the rescue, and can arrive in time.

Planning a rescue

A good rescue plan answers practical questions for each work location:

• Who will notice that a worker has fallen, and how quickly? Workers should never work at height alone with fall arrest unless their condition is monitored.
• How will they raise the alarm, and who will respond?
• What method will be used to reach the worker, and what is the backup?
• What equipment is needed, where is it kept, and who is trained to use it?
• How long will each step take, and is the total short enough?
• How will the rescuers be protected from falling themselves?
• How will the casualty be brought to the ground and handed over to first aid and emergency services?
• How often will the plan be practiced?

Rescue systems and mechanical advantage

Raising a suspended worker by hand requires lifting their whole weight, which is beyond most people over any distance. Rescue systems use pulleys to provide mechanical advantage, so that a smaller pull lifts the load. Friction in the pulleys and rope reduces the advantage, so efficiency is included in the calculation.

Drills

A rescue plan that has never been tried is a guess. Practice rescues at least once a year, and whenever the work location, the equipment or the crew changes significantly, using a dummy or a volunteer in a controlled setting with backup protection. Drills reveal the problems that plans miss: the rescue kit is locked in a trailer, the boom lift battery is flat, nobody knows the radio channel, the anchor for the rescue system is in the wrong place, or the casualty cannot be maneuvered past a beam. Time each step, record what went wrong and fix it.