Confined space medicine is practiced in areas with limited access and potentially decreased ventilation. The limited space is often secondary to the structural collapse of buildings from natural disasters such as earthquakes, hurricanes, or tornadoes. However, confined space medicine practices may be needed after a terrorist blast, fire, or in situations of poor building standards. The number of victims involved may vary, from a small number in a house collapse to a larger number in a mass-casualty event such as the 1995 bombing of the Alfred P. Murrah building in Oklahoma City which resulted in 168 deaths, or the 2001 World Trade Center attack which resulted in over 3000 deaths.
Issues of Concern
Types of Building Collapse
There are 4 general types of building collapse:
- Pancake collapse where all of the floors fall on top of each other
- Lead to collapse where the floor, wall, or beam collapses, but the structure is still supported by a remaining wall
- V collapse where the floor or roof collapses into a lower level in the shape of a V
- Cantilever collapse where the outer wall is destroyed leaving the roof and upper floors dangling.
Urban Search and Rescue
Urban search and rescue (USAR) is a unique discipline involved in the location, extrication, and stabilization of victims of confined spaces such as a building collapse. USAR is a multi-hazard discipline involving all types of disasters. USAR team members include search and rescue personnel, structural specialists, physicians, and other medical staff. Regardless of the cause of the collapse or the number of victims, the safety of the rescuer is a priority. Structural engineers are responsible for determining the relative safety of the site. Recognizing and minimizing the risk of team members becoming injured or trapped in a secondary collapse is paramount. The team leader is responsible for making the final decision whether to enter the scene. Appropriate equipment is necessary, including a helmet, dust mask, earplugs, safety glasses, heavy-duty gloves, steel toe boots, and coveralls.
On an international level, USAR is organized by the International Search and Rescue Advisory Group (INSARAG) which is part of the United Nations Office for the Coordination of Humanitarian Affairs and is a global network of more than 80 countries. In the United States, the Federal Emergency Management Agency has 28 teams across the country. Europe has similar rescue groups, and there are other volunteer USAR teams throughout the world.
USAR operations are organized into 5 stages: reconnaissance, medical assessment of victims, a search of other areas for live victims, removal of small debris by "bucket brigades," and the removal of larger debris by heavy equipment. Victims may be reached by rescue dogs or even rescue robots. Acoustic microphones help to detect victims trapped in the debris. Victim assessment can be conducted verbally, by cameras, or by fiberoptic devices.
The first 24 to 48 hours after the start of the event, or the “golden day”, is critical. As in contrast to traumas and injuries in other situations, there is no actual golden hour. If rescuers cannot immediately get access to the victims, they will often die. Patients who die in the first 24 hours usually do so from either shock or airway issues; whereas, patients who die after 24 hours usually do so from sepsis or multi-organ failure. Injuries in collapsed structures may include fractures, multiple trauma, lacerations, closed head injury, hypothermia, dehydration, and crush injury/crush syndrome. Victims can be injured by the inhalation of toxic fumes or dust.
Managing the airway in a confined space begins with the basic standard equipment including suction, bag valve mask, oral airways, laryngoscope, nasotracheal tubes, and endotracheal tubes. Other equipment such as the laryngeal mask airway, esophageal obturator airway, esophageal, gastric tube airway, lighted stylet, and cricothyrotomy kits may be useful. Extended length tubing for oxygen may be necessary. If there is a concern about dust inhalation, then albuterol or ipratropium may be beneficial.
Intubating in a confined space has unique challenges. Inline c-spine stabilization may be difficult or impossible. Spacial constraints can prevent intubation from the standard position from behind the patient. This situation will often require the face-to-face technique also known as inverse intubation or icepick intubation. The laryngoscope is still held with the right hand and the handle toward the patient’s feet, the incubator may be on the side of the patient or straddle the patient. There is no clear, proven advantage of video laryngoscopy over traditional laryngoscopy blades in this position and approach. Another technique that may be useful in the unconscious patient is digital intubation. The rescuer uses his or her fingers to lift the epiglottis and then guide the tube through the glottis and into the trachea. When a cricothyrotomy is required, a recent study showed that the Quicktrak proved faster to insert than the Melker kit. The time saving from using the Quicktrack was believed secondary to fewer parts and less manipulation required.
Mild to severe chest injuries can occur, with the worst often being fatal. Tension pneumothorax should be treated either by needle application, finger thoracostomy, or chest tube placement. If needle application is to be performed, current studies show that there is greater success with a longer needle catheter such as a 14 gauge 5 cm needle with a 4.5 cm catheter sheath. More importantly, success is also tied to the insertion of the needle in either the 4-5 intercostal space at the mid-axillary or anterior axillary line as opposed to placement at the 2 intercostal space midclavicular line.
Crush Injury and Crush Syndrome
Crush injury and crush syndrome may be encountered. Crush injury is the direct injury to the limb or organ by compressive forces whereas crush syndrome is the systemic effects from a crush injury. Systemic effects of a crush injury can include rhabdomyolysis, renal failure, sepsis, acute respiratory distress syndrome, disseminated intravascular coagulation, bleeding, arrhythmias, and electrolyte imbalance. It is the second most frequent cause of death from earthquakes, the first being trauma. The pathophysiology includes impaired kidney perfusion and intratubular obstruction by myoglobin and uric acid.
Treatment emphasizes early fluid resuscitation even while the victim is under the rubble. After intravenous (IV) access is established, recommendations are for the administration of normal saline at 1000 mL per hour tapered by 50% after 2 hours for adults and 20 mL/kg per hour for children for the first 2 hours and then 10cc/kg per hour. In the elderly, children, or those with volume overload, less fluid should be given. If it is not possible to obtain IV access, an intraosseous (IO) catheterization can be attempted. If unsuccessful in attempts for IV or IO access, then consider hypodermoclysis and administering fluids subcutaneously, with a flow rate of 1 mL per minute. Hypodermoclysis can be used in more than one location on a patient and up to 3 L can be administered per day. Lactated ringers should be avoided as it contains potassium which can worsen potentially life-threatening hyperkalemia in some patients. In general, 3 to 6 L should be given over the first 6 hours while monitoring the patient’s hemodynamic status and urine output. If there is anuria (after hypovolemia is excluded), then give only 500 to 1000 mL per day in addition to fluid losses. If close monitoring is impossible, then give up to 3 to 6 L of intravenous fluid per day. When close monitoring is available, more than 6 L can be given per day.
Once the victim is extricated, 50 meq of sodium bicarbonate can be added to each liter of half-normal saline (combined produces a solution nearly isotonic) to maintain urinary pH over 6.5. Patients in rhabdomyolysis need approximately 200 to 300 meq of bicarbonate a day.
Treatment with Mannitol is controversial given its proven efficacy in traumatic rhabdomyolysis and its side effect profile. Mannitol may be useful to increase extracellular volume and prevent the deposition of renal tubular casts, but its use may also lead to heart failure and renal toxicity if not dosed properly. Mannitol is contraindicated in oliguria, hypervolemia, hypertension, and heart failure, so the decision to give this medication should not be automatic. Mannitol, if used, should be given as a 60 ml dose of 20% mannitol given over 3 to 5 minutes to test if there is a urinary response. Mannitol should only be continued if there is a 30 to 50 mL per hour increase in urinary output over baseline. The dose of mannitol is 1 to 2 gm/kg per day for a total of 120 gm per day at a rate of 5 gm per hour.
Several electrolyte abnormalities may be present. Hypocalcemia should only be treated if the patient is symptomatic since the patient may later develop hypercalcemia. Start with 10 mL of intravenous calcium gluconate 10% or 5 mL of intravenous calcium chloride 10% over 2 minutes. Hyperkalemia should be monitored and treated based on the potassium level and electrocardiographic changes. The ECG may not change in some situations where the potassium level is dangerously elevated. If there are severe or life-threatening electrocardiographic changes or arrhythmias such as the widening of the QRS to third-degree heart block or pulseless electrical activity, the intravenous calcium gluconate or chloride should be given immediately. It may be necessary to give several doses every 10 minutes to achieve the cardioprotective effects of calcium. If the patient is acidotic then sodium bicarbonate 1 meq/kg should be given immediately IV over several minutes. To drive the potassium into the cells, 10 units of intravenous insulin, together with 1 to 2 ampules of D50, should be given. The Beta agonist effect of albuterol inhalation treatments can also help transiently decrease potassium levels. Kaexylate with sorbitol can be given orally at 25 to 50 gm, or it may be given as a retention enema. Patients with life-threatening hyperkalemia need the potassium removed from their system. The medications and treatments are temporizing measures to provide time for excretion of removal of potassium from the body. The patient may require emergent dialysis. Critiques of recent disaster responses were that there was an insufficient number of dialysis machines to treat those with renal failure secondary to crush injuries. Blood products should be given as necessary and when indicated.
One of the more severe complications of crush injury is compartment syndrome. One should monitor for the “5Ps” which includes: pain, paresthesias, paralysis, pallor, and pulselessness. However, it is important to realize that pain out of portion to the exam may be present before the other symptoms with the initial presentation of compartment syndrome. Patients may also continue to have a pulse when compartment pressures are elevated and if pulses are lost then this is a late sign. A more objective measure is to check pressures within the compartment. A pressure greater than 40 mm hg indicates the need for a fasciotomy. Although there is no consensus regarding the exact number, some sources recommend that compartment syndrome has an intracompartmental pressure of greater than 30 mm Hg, or a less than 30 mm Hg difference between intracompartmental pressure and diastolic blood pressure as an indication for fasciotomy.