By Les Baker
Published Wednesday, June 20, 2012
| From the August 2012 Issue of FireRescue
In any motor vehicle collision, there’s a potential for a victim’s extremities and/or torso to become trapped under a vehicle for a variety of reasons; the vehicle occupant could experience a full or partial ejection, the vehicle may have struck a pedestrian or cyclist, etc. The vehicle may be resting on its wheels, side or roof.
Due to the entrapment and the resulting force applied to the body, there is the potential for crushing injuries, and the extent of injury depends on how much force is applied and for how long. In addition to direct soft-tissue, continued compression will cut off circulation to the soft tissues, producing further tissue and/or organ destruction. An additional concern: chest compression that could prevent adequate respiration.
Responders must quickly prevent the application of any further pressure, using initial stabilization techniques to maintain or restore respiratory and/or circulatory functions, and determine the best lifting tactics to relieve the entrapment. A secondary benefit is relieving the psychological distress of the patient by showing them that responders are working to prevent the vehicle from crushing them further.
With this in mind, this article will concentrate on how responders can use stabilization equipment, such as wedges and strut systems, to relieve compression until further lifting equipment can be deployed.
When responding to a motor vehicle collision with entrapment, initially treat the incident like any other vehicle collision. Take the necessary steps to establish incident command, survey the scene carefully, call for resources as needed, control hazards and stabilize the vehicle in the position found.
Regardless of the type of lifting device needed to free the entrapment, first complete stabilization by appropriately placing wheel chocks, standard cribbing, strut systems and other equipment. For any situation, stabilization increases the safety of responders in and around the hot zone by limiting further unanticipated movement, and it decreases the potential for additional injury of the patient.
For lift operations, stabilization also serves additional purposes:
- It allows responders to make every effort to prevent further downward movement or compression of the entrapped body parts. There should be a short time lapse between the initial stabilization of the vehicle and the beginning of the lift operation.
- Stabilization limits any potential vibration from responders positioning lift equipment. Preparing for lift operations requires responders to work close to the vehicle and place various types of equipment against the vehicle or object. Any contact with and movement of the vehicle, regardless of how minimal it may seem, can be transmitted to the patient.
- Stabilization sets the stage for the lift operation. Correctly placing initial stabilization will ensure a smooth transition to the lift and provide additional support during the operation.
- It allows responders to use wedges and strut systems to generate a certain amount of lift. Simple machines have been used for centuries for logging, construction, etc. As a member of the Darlington County Extrication Team, I got my first exposure to this concept during a competition several years ago. Our scenario involved a patient entrapped under a side-resting vehicle. We successfully raised the vehicle using lift bags and struts, but the tactic required almost the entire 20-minute timeframe. After discussing our actions with the judges, we realized the potential to use the strut system to relieve some pressure on the patient until the lift bags could be placed in operation.
Let’s now address some specific stabilization equipment: wedges and strut systems.
Wedges represent an inclined plane and are known as one of the six classic simple machines. A wedge works by converting the force applied to the blunt end into forces perpendicular to the inclined surface. Responders typically use wedges in conjunction with step chocks and loose cribbing and, depending on the force applied to the blunt end, may accomplish some lift.
During stabilization, responders should only strike wedges enough to tighten the cribbing to the load. However, during compression situations, responders may consider larger striking tools, such as flathead axes or sledge hammers, to drive the wedges in farther. Communicate these actions with the medical personnel, as they will cause increased noise and vibration—and vibrations could impact the patient.
There are a variety of factors that will determine the overall success of this tactic. For any lift operation, consider the weight distribution of the vehicle and the lift point as well as the victim location in relation to the fulcrum. In addition, consider the mechanical advantage factor of the wedge.
A certain amount of lift can be achieved by correctly placing the strut(s) in position and using the onboard or an auxiliary ratchet strap to draw the base(s) toward the load. Although it may not be possible to achieve enough lift to free the entrapped victim, any quick relief of pressure can increase the patient’s chances of a successful recovery.
The same factors for lift operations apply to the use of struts. In addition, consider the strut/strap attachment points and angles as well as ground conditions. When placing struts in position, as the bases draw toward the load, the angle of the struts will change and potentially become less stable. To avoid this, slightly exaggerate the angle—but not so much that it decreases the ability to lift. If using two struts that are connected, sometimes only one strut will move (instead of both of them at equal intervals). If this movement can be predicted, the angle of the strut that will move can be exaggerated more than the other.
An additional way to generate more force through the ratchet strap to draw the base toward the load: Run the loose end of the strap back through the ratchet and pull down on the strap instead of the handle. This technique can generate up to 100 lbs. more force in the ratchet strap.
Departments that have lifting strut systems can take advantage of their lifting ability to relieve the entrapment. Because the lifting jacks are typically stored separate from the struts, it’s still good practice to use the strut to stabilize and relieve pressure prior to beginning the lift operation.
When victims are trapped in or underneath vehicles, responders must quickly take the appropriate steps to mitigate the pressure to prevent further physical injury and mental stress. Until lifting equipment can be deployed, responders can use wedges and struts. And always remember that when attempting to relieve pressure quickly, we must first consider how our actions affect the patient—this is our first and foremost concern.
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