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Extrication Tips: Trunk tunnelling for extrication: a viable option?

Trunk Tunnelling for Extrication: A viable option?

December 11, 2007
By Randy Schmitz


Topics

randyschmitzAt any accident scene, rapid removal of the patients out of the vehicles and off to the hospital operating table  improves their chances of survival. 

Most of us are familiar with the term “Golden Hour” that was introduced back in the ’60s, along with the “Platinum Ten,” meaning the time to move a patient from the wreck to the ambulance.

This ideal “10-minute time frame” is getting tougher to beat by the ever increasing new safety standards coming down the line. 

Let’s talk about some new proposals on the table that are over and above the standards recently introduced.

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Improved roof crush resistance and side-impact standards
The U.S. government plans to improve its automotive crash tests and strengthen its five-star vehicle safety rating system under a new plan. (Canada normally harmonizes with the U.S.)

Under the improvements suggested for the five-star safety rating program, known as the New Car Assessment Program (NCAP), vehicles will be subject to more stringent rollover, frontal and side-impact crash tests.

Each year the National Highway Traffic Safety Administration (NHTSA) performs rollover and crash tests on new cars and trucks and assigns them with a safety rating. Five stars is the top rating. Today 95 per cent of new cars receive the top ratings in crash tests, but even with those high ratings more than 45,000 people still lose their lives on North American roads each year. Consumer demand and public safety advocate groups are the driving force behind the push for auto manufacturers to design passenger vehicles that are safer.

Innovative technologies such as vehicle pre-crash avoidance capabilities, electronic stability control, occupant size discrimination controls for front passengers and notable advancements in frontal, side and roof curtain airbags and restraint devices, have made considerable gains in the efforts to save lives. Transport Canada (under the authority of the Motor Vehicles Safety Act) and the U.S. Department of Transportation are continually working together to introduce new regulations to make vehicles safer.

Notwithstanding these dramatic improvements, deaths and injuries from traffic collisions continue to be the biggest transportation safety problem in North America. Therefore, more solutions are still needed to improve occupant compartment integrity.

Improved roof crush standard proposed, Federal Motor Vehicle Safety Standard (FMVSS) 216
 The purpose of FMVSS 216 is to reduce deaths and serious injuries when vehicle roofs crush into the occupant compartment during rollover crashes.  This standard has not had a significant upgrade since 1971. Some areas that require change are:  to improve the way the roof crush test is performed; change the allowable roof crush intrusion to no more than five inches; and increase the applied-force test to 2.5 times each vehicle’s unloaded weight from the current 1.5 test load.

Improved side-impact standard proposed, FMVSS 214
The proposed upgrade will add a dynamic side-impact pole test. The test will be done on both sides of the vehicle and the pole will be aimed at the test dummy’s head placed on the front outboard seating position. Test speed will be 32 kilometres an hour at an approach angle of 75 per cent. 

With these proposed upgraded standards, NHTSA does not specify any required technologies to meet the performance standards. However, continuing to install side-impact and roof curtain airbags in conjunction with engineering changes including stronger roof rails and A-, B- and C-pillars to absorb more crash energy, seems to be the most obvious solution.

The Alliance of Automobile Manufacturers predicts the auto industry will likely meet the proposed requirements before they are scheduled for implementation. Generally for regulation upgrades there is a four-year phase-in time frame to allow the manufacturers to test and put the new upgrades into their production lines.

Some manufactures, like Volvo and Subaru, for example, have already started to improve rollover strength by using high-strength, low-alloy metals such as boron in their occupant safety cage.

Imagine a reinforcement of high-strength steel that includes welding the tops of the B-pillars to a high-strength cross-member in the roof and the bottoms of the B-pillars to a floor frame cross-member.  Basically you have a very strong, solid ring of crash protection.

The strength of this boron metal that is in the late-model Volvo XC90 has a tensile strength of approximately 195,800 psi.

Subaru has added eight layers of medium heavy steel in its B-pillars, along with 3/4-inch (19-millimetre) steel round bars welded inside the core of the pillar to increase strength.  Also, one middle layer of this pillar is exotic metal to further reinforce the pillar.

A few other vehicles with these types of similar reinforcements in their safety cages include:
Porsche Cayenne                 2002-2007
Audi Q7                            2006-2007
Volkswagen Touareg            2002-2007
Ford–Five Hundred              2005-2007
Land Rover Discovery          2004-2007
Infiniti QX56                     2004-2007
Ford Free Style                 2005-2007

How does this affect us as rescuers, you ask?
Almost all of the hydraulic cutting tools on the market today will have trouble cutting these reinforced areas, except for a couple of recently released hydraulic cutting tools that can sever material above the 200,000 psi range. Even with these tools the metal seems to just compress and become more difficult to cut.  Let’s step back a few years, when one of the common methods for patient egress from a crashed vehicle was to cut the roof off to facilitate patient removal. Easily done in the past.

Then, in 2003, some vehicles came with reinforced, multi-layered B-pillars.  Rescuers discovered they needed to revisit their current cutting practices in order to be successful in removing these roofs.

In the recent past, alternatives to cutting the reinforced B-pillars had innovative rescuers making inverted-V-pattern cuts into the roof rail, bypassing the B-pillar and basically cutting around it with their shears to release the roof.

This works well on some vehicles, but today, with more and more vehicles having the boron-strengthened roof rail, that procedure becomes ineffective. Reciprocating saws with improved rescue blades and air chisels have little impact on this metal in these areas.

On some vehicles you may be able to cut the sheet metal along the inside of the roof rails and basically leave the A-, B- and C-pillars intact, typically known in the competition circles as the “Kipper Can” technique. However, this only works if the vehicle manufacturer has not inserted transversally structural roof cross-members tying in the A-, B- and C-pillars to each other. Another procedure is flapping the roof in between these sections, but that may not leave you with a suitable patient egress path.

As you can see, it’s not getting any easier for the fire service to keep up with new technology and safety advances in modern vehicles.  The days of the “rescuer friendly type vehicles” are officially over.

How can we stay one step ahead of these never-ending new vehicle challenges?
Maybe we could revisit how a vehicle is built and attack it at its  “structural” weak point.

Let’s talk about an option that previously has been regarded as a possible plan “B” or “C” in our considerations for the best path of patient egress, rather than a plan “A.”  What we are referring to is traditionally known as “tunnelling” through the trunk or rear of the vehicle.  Generally, this technique has been reserved for “tractor trailer under-ride” situations where there is no access from the sides of the vehicle, or you have no option to remove the roof.

When we discuss the structural weak point in the vehicle, one area is the “rear trunk deck” or “rear bulk head.” This thin sheet metal structure that separates the passenger compartment from the trunk area has been virtually unchanged for many years.  We can use this weak point to our advantage and make short work of what would normally take longer to accomplish had we chosen the typical roof removal method.

Let’s look at this procedure in a step-by-step process.

The vehicle we are about to dismantle is a four-door sedan, one of the most common vehicles on the road today.  (Please note the actual vehicle shown does not have the added safety features mentioned above; however, for illustration purposes, we will assume they exist.)
 
As always, follow your department’s protocols for scene safety, vehicle stabilization, battery disconnection and SRS identification.

STEP 1
Access the trunk compartment by the ignition key, or by depressing the trunk lid open button in the glove box (this must be done prior to battery disconnection). You can also spread the trunk lid open by inserting your hydraulic spreader tips between the bumper and the outer edge of the trunk lid directly underneath the locking mechanism. This is sometimes difficult if the bumper is made of plastic and has structural foam as the core, the bumper may fail first before the locking mechanism decides to give way.  Your second attempt should be made at either side of the trunk lid near the corners.
Insert spreader tips in between the joint of the rear quarter panel and trunk lid and pry the lid up and away; it should release itself off the locking mechanism by distorting the trunk lid and twisting the u-shaped metal pin that nests in the latching component with little difficulty.
 
STEP 2 
Now with the trunk lid open, cut the trunk lid supporting arms.
Some heavier trunk lids will have small, pressurized gas shocks that assist the lid to remain open; these will also have or be cut or removed. (Caution, these shocks are under pressure and cutting the centre of the shock body should be avoided so as not to release the contents.) Insert a screwdriver or bar to pry off the bottom of the shock, which is made up of a little ball inserted into a socket. Some are made of plastic and can be removed quite easily.
Remove all trunk contents, including the carpet material lining the trunk compartment and the material covering the rear deck to expose the metal.  
                                                  
STEP 3
With the rear deck exposed to the bare metal, crews can determine the best position to make their cuts in order to remove the entire deck section in one complete piece.
Proper size-up will allow crew members to determine what tools will be most beneficial for an effective removal.
A quick look underneath the deck may reveal trunk spring tension rods, speakers, wiring and other components that should be removed so they do not interfere with the cutting path.
Next, remove the rear seatback cushion by locating the two small metal tabs at the top of the seat cushion. A screwdriver or small pry bar will give you leverage to bend the small tabs back a little to release the wire frame work that holds the rear seatback cushion in position. Now with the cushion out of the way, the entire metal support framework that the cushion was resting against is exposed.

STEP 4
Start cutting the rear deck with your tool of choice. You can start the initial cuts with your hydraulic cutters, then continue them with an air chisel or reciprocating saw.  A good demolition blade in a reputable reciprocating saw seems to cut the most effectively and is the least time consuming.
Some rear deck platforms may also have additional support brackets on the underside that are attached to the side of the rear quarter panels; these should be cut off to create as much room as possible. The exposed vertical support member that the rear seatback cushion rested against can now be cut out as low as possible.

STEP 5
With the rear deck and vertical support bracket removed in one piece, and all sharp edges taped off or covered, you will now be left with the lower rear seat cushion still attached to the floor with metal tabs.
To remove this you should be able to “unclip” the wire framework out of the small metal tabs at the front of the seat, similar to the method described in the removal of the rear seatback tabs.
Note: Some lower seat cushions may be bolted to the floor hump that the cushion rests on. Simply cut these metal tabs with an air chisel or reciprocating saw.
Rear seat-belts will need to be cut or the buckle portion slipped through the cushion slots during removal.
Once the seat cushion is relocated you should have created a large opening between the roof and the vehicle floor roughly about 3 x 3.5 feet (91 x 106 centimetres) in diameter.  
                                                                            
STEP 6
At this point in your evolution, you now have access to recline the front seat backs to ready your patient(s) for removal.
If you do not have a patient in the front passenger seat it is advisable to check how far back that seat will recline in order to determine if it will allow enough clearance between the roof and the patient sitting in the driver’s seat.
If the seats do not lower down far enough to gain the required amount of clearance with a backboard in place, you will have to cut the front seatback off.
First cut away the seat material surrounding the lower seat bracket hinge areas to obtain a clear view of how and where you need to make an efficient cut. (Be mindful of undeployed side-impact airbags within the sides of the seatbacks.) Too many times we see rescuers wasting valuable time cutting away blindly at or near these hinges to no effect if they cannot see them properly.
Next, for smooth and easy cutting, make your cuts just above both the left and right seat bracket hinges with either a reciprocating saw or air chisel.
Do not cut through the hinge itself because it is the strongest component of the seat construction and will be very time consuming.  It is also not recommended to use hydraulic cutters because of the torque generated during the cut that can then be transferred to the patient. 
Cutting a seatback with a patient still occupying the seat requires diligent coordination and very clear communication between the tool operator, the rescuer in charge of the patient and the rescuer holding the hard protection between the seat and the patient. 
Note: Using the tools listed above within the passenger compartment can be quite loud, so proper hearing protection for rescuers and patients may be needed.              
                                 
Prior to the front seatback being removed, the patient must have their seat belt removed or cut off and their torso supported. Cover up all sharp edges in the egress path that were made from the cut out metal components.

You are now ready to insert a long spine board underneath the patient.

Other problems you may encounter are trapped knees from the dash area being pushed onto the patient, a hydraulic spreader or mini ram placed near the centre console area under the dash or used in tandem should be able to free the patient. Often they are just trapped by the plastic components of the dashboard.

Last November, I had the opportunity to judge in the 2006 TERC USA National Extrication Challenge, held in Las Vegas, Nev. For those of you who are not familiar with TERC (Transport Emergency Rescue Committee) extrication challenges, they are held across the U.S. and Canada at regional, national and international levels annually.

Teams consisting of five or six members extricate live patients in simulated accidents during a 20-minute, time-limited scenario.  The type of scenario the team is competing in (limited, unlimited or rapid) will determine what extrication tools the teams are allowed to use during their event. In the unlimited pit, hydraulic rescue tools are allowed; in the limited pit, no hydraulically operated tools can be used, but teams may choose to have in their arsenal electrically powered reciprocating saws, air chisels or manually operated spreaders and cutters. Basically, hand tools are the name of the game during this type of scenario.

Winner of the 2006 National and International Extrication Challenge “1st Overall Team” and numerous other challenges was the Palm Harbor Fire Rescue Extrication Team.

I spoke with incident commander Dan Zinge, and asked him to explain why they choose this procedure.

He stated: “In the field we determine our extrication strategy by what is in the best interest of the patient.  If the patient is determined to be a rapid removal based on their injury status (red or black) then we do whatever it takes to remove the patient quickly.  Anything short of that then we develop a plan based on how we can provide the best care possible which includes safe removal.”

The standard of care for treating injured people inside vehicles is to maintain control of the cervical spine throughout the removal process.  The best way to accomplish this is to, whenever possible, remove the patient in the direction that best enables constant, inline cervical stabilization.  This direction is usually determined by seeing how the patient is positioned inside the vehicle.  For example, if the patient is lying across the front seat, then our plan “A” would be to do a side blow-out to help facilitate removing the patient inline.  However, if the same patient is seated in the front seat, then our first plan would be to do either a complete roof removal or a rear tunnel job. 
                                                                            
Palm Harbor’s philosophy on performing roof removals and tunnelling is based on one basic principle, risk versus benefit.

With continued development of occupant supplemental restraint systems (SRS), roof removals are becoming increasingly dangerous for rescuers.  The use of low density metals such as boron to reinforce door-side panels and “A” and “C” posts making roof removals obsolete.

Knowing that the vehicle safety industry is continually changing its strategy to keep people safe inside of vehicles, our strategy, as rescuers must also evolve to meet the challenge.
 
                                                                            
Conclusion
The fire service will always develop a variety of techniques to enable rescuers to extricate patients from vehicles involved in motor vehicle accidents.

These procedures will have indications, contradictions, special precautions and side-effectsside effects in the same manner as any other intervention, but with diligent practice and by maintaining current knowledge of modern vehicle construction, rescuers will adapt and win the battle.

Always remember, “Train smarter, not harder.”

Randy Schmitz was been involved in the extrication field for 14 years. He is a firefighter/extrication instructor with the Calgary Fire Department and has competed in all levels of competition including Regional, International and World Challenges. Randy is also the Alberta chairman for the Transport Emergency Rescue Committee in Canada, a regional judge for T.E.R.C. and an instructor of extrication courses across Canada and the U.S. Randy continues to do extrication training and can be reached at rwschmitz@shaw.ca .


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