You and your partner are on your station's daily grocery run when the unexpected happens: Dispatch alerts units of a possible trench collapse in a construction area just one block from the grocery store where you're shopping. As you arrive on scene and park your ambulance, it hits you: Dirt! There's dirt everywhere. So are construction equipment with engines idling, a half-buried man having breathing difficulty and about 65 people who all want to know what you're going to do about the awful situation. To compound matters, the dispatcher and all other responding units are calling you on the radio, asking for a status report.
Between silent screams you ask yourself, ˙Am I EMS or rescue? What's my primary job? Patient care? What can I do to help stabilize the situation until the technical rescue team gets here?Ó The one thing you remember from trench-awareness class is tonot jump into the trench and potentially become the next victim.
With the exception of command personnel,trench rescue involves responding professionals who are responsible either for protective system placement and extrication or for patient care. Technical rescue situations require difficult, personnel-intensive work and demand that all responders add as much value as possible to the rescue effort.
Those who've been involved in rescue work for any length of time understand that in any given situation, we can be called upon to perform many different jobs. With such specialized rescue situations as trench collapses, the interaction between functions becomes more critical as the situation becomes more technical. In these situations, it's imperative that each of us, regardless of assignment, helps those performing other functions to improve the victim survivability profile. (The victim survivability profile is a determination made on the basis of a thorough risk/benefit analysis and other incident factors that address the potential for a victim to survive or die with or without rescue intervention.) Under the incident command system, each person has a primary assignment to perform, even though they may be cross-trained.
EMS providers are frequently the first on scene at a trench collapse, even arriving before technical rescue teams. If the EMS function is primarily to staff an ambulance or a medic unit, awareness-level training is likely the only trench training they have. However, EMS providers can make many positive contributions to reduce the level of risk for the patient, bystanders and all responders, and to accelerate patient removal. This article focuses on those responsibilities of an EMS providerƒsomeone whose primary job is patient careƒbefore, during and after thetrench rescue emergency. The specific activities detailed include trench scene assessment, hazard identification and considerations for patient care, packaging and removal.
The basics oftrench rescue
As with all emergency incidents, fire and EMS agencies are dispatched to respond to varied trench and excavation emergencies. The frequency of trench collapses depends on the amount and types of new construction projects underway in your jurisdiction and often on the educational level of contractors in your area and the safety programs they have completed.
Literally hundreds of trenches and excavations are opened daily (see photo, p. 72) for a variety of reasons, including the:
- Placement of underground utilities (e.g., water, natural gas and other fuels, electricity, sewage and drain systems);
- Removal of old utility systems;
- Removal of underground storage tanks (UST);
- Construction of building foundations or large high-rise operations;
- Construction of basements;
- Construction of housing developments;
- Construction of tunnels or major water projects; and
- Construction of pump stations.
A trench collapse isn't the only type of emergency that you'll respond to involving trenches. In fact, most emergencies involving trenches deal with an incident other than a collapse. A lot of work goes on after the trench is dug: Pipes are placed, electric lines are run underground, concrete is poured in molds, and supports are positioned in the trench. This work takes place in protected and non-protected trenches. The challenge is to not be lulled into complacency by protected trench situations or to assume that these rescues will be easily accomplished.
It's necessary to understand the various circumstances that could confront an EMS provider on scene at atrench rescue. Although just about anything could happen, trench accidents generally can be broken down into two broad areas: accidents with a cave-in and incidents without a collapse that can be attributed to some other accident.
Keep in mind all of the things that have to go right with the equipment at a work site: The backhoe has to work properly (Note: Its weight alone can cause a trench to collapse), the load has to be rigged properly, and the rigging has to be strong enough to carry the load. When problems occur in any one of these areas, you may find yourself in a trench rescuing a trapped or injured worker.
Hydraulic failures during lifting operations and rigging that's improperly assembled or inappropriate for the load being moved can cause construction accidents.
The machines operating at a trench site are powerful and lift heavy loads. Workers are sometimes pinned between steel panels or water and sewage pipes they are trying to set into place. When this happens, you may be faced with a seriously injured victim.
These scenes call for a rapid size-up of the protective system put in place by the construction crew and continuous evaluation to determine if your extrication methods compromise that system.
Several other non-collapse situations can create injuries or incidents that require EMS response, including:
Rigging incidents:The loads being moved in and around trenches are only as safe as the rigging and the rigger who secures them. If a rigging strap breaks or a crane's hydraulic system fails and a pipe falls on a worker, you could be faced with a crushed patient who is dead or dying. Even if the trench is protected, getting the victim out may be a major challenge.
Atmospheric conditions:This is another area of concern and a frequent cause of problems at trench sites. Even with today's stringent hazmat laws, it's not unusual to find hazardous waste products buried underground. Workers and rescuers in or around a trench when one of these containers is broken could be confronted with an atmosphere well within explosive ranges, above permissible exposure limits for toxic atmospheres or accompanied by a low oxygen profile.
Approach with extreme caution any scene with workers ˙downÓ in a trench when there's no obvious explanation for their unconscious state. If just one worker is involved, you may assume an injury or a medical problem exists. But, if two or more victims are involved, your internal warning alarms should be sounding.
Don't get lured into a death trap by assuming that a medical emergency needs your immediate attention when, in fact, a gas or other hazardous situation is the cause of the incident. It's always a good idea to have a hazmat team available as a part of your initial response to any trench collapse.
Trench rescue assessment
If you find yourself the first arriving EMS crew on scene at a trench emergency, there's plenty you can do prior to the rescue team's arrival. Most of these activities involve scene assessment, or size-up.
Assessment, the foundation on which the rescue team will build their decision-making platform, involves situational size-up, taking the time to figure out what has happened, analyzing the information and then developing a coordinated plan to address the situation. It helps determine a set of guidelines for action. Assessment occurs during three time periods: 1) from the time of dispatch until you arrive on scene; 2) when you first arrive on scene; and 3) continuously throughout the rescue. Considerations specific totrench rescue operations include:
Time of dispatch:At the time of the dispatch, you'll begin the process of gathering information. This information will come from dispatch data supplied to the communication center when the call is received. The typical call will reference a collapse of some sort, and information will be sketchy. The caller may not have known exactly what happened, or the dispatcher's initial questioning may have been inadequate. Prompt the dispatcher to seek additional information while you're en route.Some appropriate questions:
What happened?Have the dispatcher call back the initial caller and keep them on the line in case you have additional questions or need help to find the incident's exact location.
Why was the excavation work being done?
Is/are the victim(s) completely buried?The answer to this question allows you to begin your risk assessment, gives you an early indication of whether your operation is a body recovery or a rescue operation and aids in determining the amount of resources required to get the job done.
Is it a trench collapse or an injury in the trench?As discussed earlier, most trench emergencies result from a situation other than a collapse. If the victim is injured but not buried, you're dealing with a very different type of call.
Is there easy access for vehicles, equipment and rescue personnel? Generally, new construction areas don't have an established road network, which could result in a delay in getting resources to the scene. Necessary equipment may have to be carried to the site if you can't get your apparatus close to the collapse.
How is the weather, and can I expect it to change if this becomes a long-term operation?The collapse itself may have been weather-induced, caused by rain and heavy mud that broke free. In any case, consider the possibility of weather conditions changing. For instance, you may need water pumps if it's raining or a storm is expected. If it's going to get hot during the rescue, you may need more personnel than normal and additional rehab resources. Also consider lighting needs during overcast conditions or incidents that extend into the night.
Arrival on scene:On arrival, you need to finish gathering information and develop a plan for mitigating the incident. This means taking the basic information you've been able to gather, adding to it what you can obtain from witnesses or coworkers and assimilating it with what you can observe with your own eyes. Some additional on-scene considerations include:
Who's in charge, and what has happened?Question competent workers on site. They'll provide you with information about the original depth and width of the trench and what type of protective system was, or is, in place (if any). You'll also want to find out what the victims were doing just prior to the collapse and where they were last seen.
Is there a language barrier?Nothing can be more frustrating than trying to handle an emergency and not being able to communicate with the person who can give you necessary information. If a language barrier exists, find someone on site to interpret or have an interpreter dispatched by your communications center.
Based on equipment needs and limitations, is the rescue within your scope of operations? Remember, your equipment has limitations. If the trench is deeper than 20 feet or if a massive cave-in has occurred, commercial stabilization techniques and equipment will be necessary.
What are the injuries?How serious are the victim's injuries, and do you have discretionary time in providing treatment? For instance, will the extrication process take so long that the victims may die, or can you just hook them with a pike pole and pull them out? Although our goal is always to maintain good C-spine immobilization for victims, potential paralysis is not as significant a concern as imminent death and the need for immediate extrication.
What is the victim survivability profile?If your victim is buried and there's no chance they jumped in the end of a pipe for protection, you're most likely dealing with a recovery, which is no longer an emergency. Don't get your people hurt!
What type of protective system is/was in place?This information will be important because if the original protective system failed, you have a big problem. You may have to remove what was in place and start over or try to figure out a method to stabilize the existing system. At this point, if you're dealing with a fatality, call OSHA or other professional engineers for help.
To assist you in making proper scene assessments attrench rescues, consider having a checklist available for responding units (see Sample Checklist, p. 74).
Considerations during the emergency:Scene and hazard assessment requires a thorough evaluation. Reliable information will lead to a solid plan of attack. Don't make a move until you've fully assessedƒand reassessedƒthe situation.
Keep in mind that everything done at a trench collapse makes it a different scene with new considerations and hazards. These situations are so dynamic that constant evaluation for changing conditions is of paramount importance. It will help you anticipate potential problems so you can remain proactive and not become reactive.
Factors to consider when looking for buried victims:Frequently, when you arrive at a collapse site, your victim's location will be noticeable, or a competent person will have a good idea of the general area in which the victim was last seen. If not, the first place you should expect to find a victim of a trench collapse is at the end of the pipe stringƒthe last location where work was taking place.
Other specifics, such as the depth of the trench, may be determined by looking at the engineer's flagstick. Normally, the flagstick will be marked with the trench depth and grade information. You may also be able to look at the orientation of laser targets, if they haven't been moved.
If the collapse occurred at the end of a pipe string, listen for sound in the pipes. The victim may have been able to get their head and chest into the exposed pipe before the collapse. Go back to the point of origin or nearest pipe entry point and listen for sounds from the victim.
Keep in mind that if you enter the pipe for rescue purposes, you are now operating in a confined space, with the additional considerations necessary for this type of rescue.
Of course, it's more difficult to find a buried victim when the specific location is in question. Use the information you gathered during the assessment, and consider what the victim was doing at the time of the collapse. For instance, if they were sighting the hole for depth, you may find the victim at the bottom of a grade pole.
In addition, paint and grease buckets may have been located on top of the trench, positioned within easy reach of the worker. The same is true for tools and other equipment. By far, the best indicators of victim location are nearby drink containers; refreshments are usually well within the reach of trench workers.
Exposed limbs are, for obvious reasons, a good indication of victim location. This is only mentioned here because caution has to be taken when assuming exact victim location based on exposed body parts. The exposed limb may not be in normal orientation for the human body. Be careful when digging around victims until you are sure of the head and chest location.
Hazard control:After the initial assessment, turn your attention to any real or potential hazards that need to be addressed prior to conducting rescue efforts. Your quick identification of these risks can save valuable time when specialized rescue personnel arrive on scene. This size-up may also save your life or the lives of other responding personnel. Because EMS personnel are already experienced at scene size-up, many of these suggestions will come as second nature. However, due to the specialized nature oftrench rescue and the fact we don't routinely respond to these events, you may not normally consider several of these factors.
Hazards can be broadly categorized into one of two types: those you can control and those you should leave alone.
Hazards that can easily be controlled and are within the expertise of the rescuer need attention before the deployment of personnel. Such hazards include the location of vehicles, trip hazards, movement of the spoil pile, stabilizing or supporting existing utilities, etc. Examples of hazards that should be addressed by someone else are electricity and gas.Rule of thumb: If a professional discipline is normally contracted to place or maintain the utility, it's a good indication you're not qualified to handle hazards associated with it. Call a professional if there's any question or if the situation is beyond your training, abilities or equipment.
More specifically, five types of hazards exist: mechanical, chemical, man-made, electrical and water.
MechanicalƒMachines and other entrapping mechanisms could pose a danger to rescuers. The weight of the machines or the vibrations from generators or other equipment can cause additional collapses or cause dirt to fall into the trench. Make sure you bring everything to a zero mechanical state: Eliminate all possibility that activation could take place. Take the keys out of machinery, lock out electrical devices, and move machines away from the collapse zone.
ChemicalƒAlways assume that something could have been unearthed during digging operations. In addition, a worker may have carried a chemical into the trench for use during intended work activities.Examples: gasoline for saws, solvents for cleaning and glue for making pipe connections. Never assume anything is safe, and always monitor the atmosphere.
Man-madeƒMan-made hazards are usually the reason you're there to begin with. These hazards result from our normal work.Examples:spoil pile location (it could fall back into the trench), equipment location at the scene, tripping, etc. When considering the shutdown of heavy equipment, consider if it's attached to anything. If you elect not to move the equipment, keep the operator on scene. In all cases, remove the key.
ElectricalƒIt's always been my policy not to mess with electricity. I'mnot referring to shutting off breakers, but rather to dealing with pole, cable and transmission box hazards. Controlling electricity is best left to the people who do it for a living, not us part-time hazard-control experts. Also watch out for telephone lines. The voltage carried in telephone lines can knock the fillings right out of your teeth. As a practice, determine all utility locations before digging in a collapse area. This can be accomplished as simply as calling the local utility company, or the foreman may have a utility map of the area.
WaterƒIf rain is imminent, consider building a cover for the trench and establishing a method to divert incoming water. The bottom line is to get existing water out of the trench and do your best to see that no additional water gets in it. Have water pumps brought to the scene.
Patient care considerations
After the technical rescue team arrives and you've advised them of your assessment and hazards, you'll turn most of your attention to patient care. However, you should keep in mind that these incidents evolve slowly. You may have opportunities to provide other support activities before you're presented with a patient. Some of those activities include ventilation, rehab or assisting the Incident Commander with scene access control and accountability.
Who will provide the EMS care:It's vital to consider who, exactly, will provide patient care. The removal of a partially buried patient will likely take time, and patient care typically starts before victim removal and continues during packaging.
As the rescue team establishes a safe zone around the patient, the Extrication Officer will want to put a paramedic in the trench to perform a primary assessment and begin patient care. Placing an EMS provider into an environment in which they are uncomfortable or unfamiliar is never a good idea. If the paramedic is concerned about their safety because they're unfamiliar with the environment or protective system functions, they won't be concentrating on their primary dutyƒpatient care. Also keep in mind the limited room in which to provide patient care once rescue shoring is in place.
It follows that the person sent to assist the patient must be comfortable with the environment. It's, therefore, important to obtain specialized training if you are an EMT or a paramedic with the potential to provide care in this very technical situation. (FEMA's Virginia Task Force II Urban Search & Rescue Team provided training to all of our doctors and paramedics in structural collapse, trench, confined space and rope rescue.)
Concerns for all patients:Let's assume that the trench has been made safe and that you are ready to enter and begin the assessment and treatment of your patient. Remember the first rule of medicine: ˙Do no harm.Ó Always protect your patient from further injury and proceed with caution.
Most scenes will be cramped, and you'll have limited room in which to work, making assessment and treatment a challenge. Often, the trench will be muddy and contain water, creating a slippery, uncomfortable, intimidating situation. Do your best to block out distractions and to concentrate only on patient care.
During scene size-up, determine if your patient suffered some type of injury or experienced a medical problem. If an injury has occurred or the patient has fallen, use C-spine precautions, if possible.
Start your assessment with the ABCs. First, check for an open airway and secure it as necessary. Place an oral airway if the patient is unconscious and will tolerate it, but be prepared to intubate if required.
Once you've secured an airway, assess your patient's breathing. If the patient isn't breathing adequately, administer supplemental oxygen and assist with ventilations, if required. One trick to administering oxygen in a cramped space is to keep the oxygen bottle outside the hole and add extension tubing to the delivery device via an inexpensive, double-male adapter. If the patient is having breathing difficulty for no apparent reason, remember to evaluate for the possibility of a toxic or oxygen-deficient atmosphere. Make sure the trench is well ventilated and constantly monitored.
Next, assess your patient's perfusion. This can be accomplished by checking capillary refill, taking radial, brachial or carotid pulses or a blood pressure by palpation. The trench environment may be noisy and make it difficult to auscultate blood pressures.
Once the primary survey has been completed, proceed with your secondary survey and check for any additional life-threatening injuries. If none are found, prepare to package your patient for removal. It will be much easier to continue patient care once the victim is out of the trench and in your ambulance.
If additional life-threatening problems are found during the secondary survey, treat them as quickly as possible. Traumatic amputations and crush injuries tend to bleed moderately and can be stabilized with a bulky pressure dressing. If major extremity hemorrhage is present and can't be controlled with a pressure dressing or direct manual pressure, use a blood-clotting product, if allowed by your state and regional protocols. A BP cuff applied over a dressing can be inflated to apply direct pressure when hand pressure cannot be applied. You will have additional time to control bleeding once the patient has been removed from the trench. The placement of a tourniquet should be your last resort.
Non-life-threatening fractures should be stabilized by securing them with the patient to a long backboard. Don't take the time to splint these injuries in a trench unless the patient is completely stable and the scene is safe. Once the patient has been removed from the trench environment, treat them as you would any other victim of trauma or illness.
Patient care when a collapse is involved:If the victim is completely covered, try to determine where the patient's head is and uncover the head and chest first. Be aware that the patient's mouth and airway may be full of dirt and foreign matter. Clear the airway as quickly as possible by any means available. Use your fingers and suction from at least one portable suction device to remove the obstructing debris, and then attempt to ventilate the patient. If you don't succeed, look deeper in the patient's airway for additional debris.
Once the airway is clear, check for adequate breathing. If the patient's chest and abdomen are covered by earth, breathing may be restricted and compromised.Note:If the dirt in the trench is dry or sandy, it will easily move and flow around the victim and cause additional chest restriction. Each time the victim exhales and his chest deflates, dirt will flow in and fill the void, causing more restriction. Therefore, clear the dirt from around the victim's chest to allow proper lung expansion as soon as possible. If a rated sling or rescue quality rope is placed on the patient to keep them from sliding down deeper in a hole, make sure it's not restricting the patient's breathing or complicating their condition.
After the head and neck are clear, place a cervical collar for stabilization. If the patient can communicate with you, ask if they are aware of any injuries in the area still covered by dirt.
Uncovering a person's buried limbs can be slow work, and you'll need to provide emotional support for your patient during this process. However, you can also use this time to plan how to manage additional injuries. For example, if the patient tells you they think they have a broken upper leg and it feels wet, be prepared to handle an open femur fracture and have the necessary equipment ready for when the injury is uncovered.
As soon as an extremity is uncovered and accessible, establish an IV of normal saline with a 16- or 18-gauge catheter. This can be used for fluid replacement or drug administration, if necessary. Remember to secure your IV well because there will be a lot of patient movement and many people working in the area.
If the victim's chest is uncovered and circumstances allow, place a cardiac monitor on the patient and check for abnormal rhythms. As the extrication proceeds, monitor your patient's condition, and, again, constantly provide emotional support. This is important and will have a positive impact on your patient's outcome.
Special considerations:During a prolonged extrication, the trench environment will be cooler than the surrounding area, and hypothermia could be a concernƒeven in summer. The earth below grade remains at a constant temperature, usually in the low 50s, year round. Prolonged contact with this earth can lower the patient's core temperature, and, because most trench environments are wet or contain water, the patient may be surrounded by water or mud, increasing their body's rate of heat loss. Inclement weather can also lower a patient's body temperature
Try to keep your patient as dry as possible, and limit their contact with the ground if you can. Place some form of insulation, such as an isothermal blanket, under and around the victim to prevent heat loss. The use of a foam pad, extra turnout gear or blankets will also help. Hot packs under a patient's armpits or around their neck/head region will warm them. You can also direct portable quartz lights toward the area to add heat, if the environment is safe.
A condition known ascrush syndromeoccurs in prolonged entrapments where the victim's body tissue is crushed and circulation to the tissue is restricted. Because the blood flow is reduced or absent, the affected tissue becomes acidotic, and lactic acid builds up. When the crushed tissue is relieved and circulation restored, blood dumping into central circulation causes such problems as cardiac arrhythmias and electrolyte imbalances. Although an exhaustive review of crush syndrome is beyond the scope of this article, you should be aware of its potential problems and monitor and treat your entrapped patients for this condition. (See ˙Crush Syndrome,Ó January 2000JEMS,and ˙Under the Metal,Ó August 2001JEMS.)
When a patient is entrapped for an extended period of time, they may deteriorate to a point where defibrillation or CPR is required. You must be prepared for this situation and its potential hazards. Remember, a patient trapped in a trench environment may be wet. If defibrillation must be attempted, make sure your patient is dried off as much as possible, defibrillation pads are securely in place and the area is as clear as you can make it.
If the patient's condition continues to deteriorate and they progress to asystole, carefully consider all factors before starting resuscitation efforts. Effective CPR will be difficult, if not impossible, when a patient is trapped in a trench environment. If removal of the victim is expected to be a long process, you should reconsider the entire situation and your termination of care protocol before starting resuscitation efforts. If you have a question regarding whether you should begin CPR, contact medical control and seek advice.
EMS personnel on scene at a trench collapse have many responsibilities. By providing an early assessment of the scene and identifying known and potential hazards, you can help expedite patient care. Seek additional training in the specific rescue disciplines for which you will be providing patient care. Advance planning and proper training are the keys to successful resolution of any rescue event.
- Martinette CV:Trench Rescue: Training Levels: Awareness, Operations, Technician(Instructor Guide, Student Workbook and Operational Field Guide). Jones and Bartlett, 2004. (Available viawww.TrenchRescueBook.com.) Meets NFPA Standard 1670 requirements.
- NFPA Standard 1670.
- Stanevich RL, Yokel FY:Development of Draft Construction Safety Standards for Excavation.NBS (NIOSH) Publication, NBSIR 83-2693; DHHS (NIOSH) Publication No. 83-103. U.S. Department of Commerce, Washington, D.C.; Department of Health and Human Services, Morgantown, W.Va., 1983.
- Yokel F:Soil Classification for Construction Practice.Report NBSIR 79-1945, U.S. Department of Commerce, Washington, D.C., 1979.
Most construction companies are required to comply with such standards as OSHA's ConstructionƒTrenching and Excavation standard. Thus, i