Earthquakes

Earthquakes are a well-known and publicized model of a disaster that results in significant mortality,¹⁷ as can be seen in Figure 226-1 describing deaths from earthquakes since 1990. A homogenous population well trained in basic trauma and life support and the architectural design of the stricken area’s housing and public facilities are two major determinants of outcomes for earthquake victims. The massive earthquakes of the past 10 years in Turkey, Taiwan, Sumatra, Kashmir, Sichuan, and Haiti have shown us that sound engineering design for earthquake resistance in civil structures such as schools, hospitals, fire stations, and correctional facilities have a major impact on outcomes. In addition, urban earthquakes generate massive fiscal impact on the world in terms of reconstruction grants provided by wealthier countries for devastated urban areas. Moderately destructive earthquakes in the developing world usually cost up to $10 billion in reconstruction; the needs of developing countries with urban earthquakes may cost an order of magnitude more.

Figure 226-1 Deaths from earthquakes since 1900. The toll of the Haiti quake is more than twice that of any previous magnitude 7.0 event and fourth worst since 1900.

(From Hough SE, Bilham R. After the earth quakes: elastic rebound on an urban planet. New York: Oxford University Press; 2006; and from Bilham R. The seismic future of cities. Bull Earthq Eng 2009;7:839–87.)

Despite extensive experience and published literature dealing with medical response to earthquakes over the past 30 years and publications devoted to compiling the experiences of disaster management focused on critical care, current experience with the earthquake in Haiti shows that we are frequently doomed to relearn the lessons forgotten.

The Haiti earthquake occurred on January 12, 2010, and was of magnitude 7.0 on the Richter scale, resulting in some 230,000 mortalities and 1.5 million homeless. Let us consider first the military medicine response delivered, especially in the face of continuous exposure of the military medicine establishment to mass casualty management in the wars in the Middle East.

Responders from the very experienced Israel Defense Forces (IDF) air-deployed within 48 hours of the Haiti earthquake. This team had extensive experience over the years with international response and consists of 230 people. The team unpacked and built their portable hospital within 8 hours, and during 10 days of operation treated more than 1100 patients in a facility designed to provide 60 inpatient beds, including 4 intensive care beds and 1 operating room.¹⁸ Most of the first wave of casualties presented with crushed limbs with open infected wounds, with the later arrivals presenting with sepsis and poor chance of outcome. Despite the repeated experience from prior earthquakes showing that victims of crush syndrome and acute renal failure require emergency dialysis to prevent death, this facility relied on other international teams for dialysis. Their major dilemmas were practical implementation of the triage algorithm by military personnel to a civilian population. The simple priorities were urgency, resources available, and probability of saving life. Patients with brain injury, paraplegia due to spine injuries, or a low Glasgow Coma Scale score were immediately transferred to other facilities, since no neurosurgical capabilities were available. A triage panel of three senior physicians relieved individual physicians of personal accountability. Half of the intensive care capability was always dedicated to postoperative care, with the remaining 2 beds used for prolonged intensive care; only patients who were expected to stabilize within 24 hours were placed in these beds. The very early discharge policy permitted this military facility to treat more than 100 patients per day.

Second, let us consider the response of the U.S. military, which at this point had a considerable portfolio on providing international disaster relief in catastrophic events such as the Indonesian tsunami that devastated Sumatra. The United States Naval Ship (USNS) Comfort, one of Military Sealift Command’s two hospital ships, was deployed as part of the mission termed “Operation Unified Response.” It started accepting casualties within 7 days of the earthquake. The ship is a 1000-bed facility which includes 75 intensive care unit beds, blood bank, hemodialysis, pathology, physical therapy, morgue, and radiology with computed tomography and ultrasonography capability. It is staffed with 1000 active-duty U.S. medical personnel, including three physician intensivists, and it was allocated to stay up to 6 months.^19–20

The first wave of casualties were critically ill trauma patients airlifted from field hospitals by U.S. helicopters. Within 72 hours, the Comfort admitted 254 patients, and the census rapidly increased to 430, more than a third of them pediatric cases. A team of 6 internists provided 24/7 coverage. Dozens of patients underwent mechanical ventilation simultaneously, open-bay design did not allow for isolation, and the nurse-to-patient ratio was about 7 : 1. A large volume of hemodialysis was provided to patients with crush syndrome, leading to rapid depletion of dialyzers and dual-lumen dialysis catheters. The discharges exceeded admissions in about 2 weeks, and after a total of 629 admissions, the ship completed its mission. While the standard of care exceeded community expectations, the U.S. Navy personnel followed naval protocol and standards.

Third, let us consider the relearning of the lessons of civil-military collaboration in disaster response.²¹ A volunteer medical team with civilian personnel under the auspices of the international medical corps flew to the Dominican Republic and reached Hopital de l’Universite d’Etat d’Haiti in Port-au-Prince after a long bus ride on January 17. There were more than 800 injured in the partially destroyed facility, with the primary diagnoses being crush injuries, compartment syndrome, infected fractures, and hemorrhagic shock. One physician and one nurse were covering up to 80 critically ill patients in the wards. An aftershock of 5.9 magnitude resulted in an exodus of casualties and higher rates of heat stroke in dehydrated hypovolemic patients exposed to tropical temperatures. Destruction of the prison system released some 4000 criminals into the community, and no security was available until arrival of a U.S. airborne infantry regiment. With arrival of the USNS Comfort on January 20, evacuation of the most critically ill patients started, but a triage list developed rapidly, with ship facilities accepting preferentially complicated injuries, obstetric patients, and maxillofacial injuries. Patients with pelvic fractures, closed head injuries, complete spinal cord lesions, and mechanical ventilation cases were of too-high acuity for the USNS Comfort. Family structures became fragmented as separation of children from parents occurred. Yet the collaboration of civilian and military medical personnel was considered a success.

Next, let us consider the experiences of academic centers delivering care to victims of the Haitian earthquake on-site.²² The Miller School of Medicine of the University of Miami and Project Medishare had the advantage of long experience of collaboration with Haiti as well as close geographic proximity, and they were able to provide emergency relief within 20 hours. Within 8 days, they were able to establish a field hospital at the city airport, and by January 21, 140 patients were transferred into the upgrade facility. The well-organized command center with satellite links for telephone and Internet access were available. A joint adult-pediatric triage team accompanied by Creole-speaking medical staff of Haitian origin was used. Multiple surgeries were performed under local peripheral nerve blocks, with guillotine amputations being frequent. Highest-acuity patients were transferred to the IDF field hospital or the USNS Comfort. The command center eventually provided psychiatrists to manage the posttraumatic stress syndrome and a buddy system for follow-up support.

Finally, one must consider the critical care response from New York City. While many small teams and a large volume of supplies were dispatched, an organized response was delivered under the leadership of Dr. Ernest Benjamin, division chief of critical care in surgery at Mt. Sinai Hospital. Dr. Benjamin, with close family ties to Haiti, arrived in Port-au-Prince 3 days after the initial event and after rapid assessment of needs and resources available, organized the deployment of the 27-member critical care team to his home country, which arrived on January 20. The team remained on-site for 2 weeks and was responsible for postanesthesia and postoperative care delivery, with Dr. Benjamin being deputized as the director of critical care and recovery at the national hospital. The home institution effectively secured anonymous donations of private jets able to transport the team personnel and some 3000 pounds of medical supplies per flight. The team delivered intensive care with minimal technology but with kindness and dignity towards the suffering population. This certainly was not a medical tourism venture but a true integrated response with both language and cultural sensitivities and capabilities, so important in catastrophic situations that will take decades for the local population to recover from.²³

Experience in managing catastrophic international disasters continues to accumulate with unfortunate regularity. The preceding discussion suggests that combinations of dialysis, orthopedic surgery, pediatric trauma, security, transportation, posttraumatic stress treatment, and cultural and language sensitivities are crucial in earthquakes. Disasters produce well-defined syndromes with well-defined mortalities. It is the recovery phase that continues to require persistence and improvement. One of the most experienced managers and thought leaders in disaster management, Dr. Eric Noji, enumerated the most important factors in public health after disasters: environmental health, epidemic management, immunization, controlling the spread of HIV/AIDS, management of dead bodies, nutrition, maternal and child health, medical services, and thorough public health surveillance. It is a common error to deliver a few weeks of heroic quality care then abandon the population to the ravages of destroyed infrastructure, including public health organization.²⁴

Volcanic Eruptions

A volcano is a hill or a mountain built around a vent that connects with reservoirs of molten rock below the earth’s surface.²⁵ Different types of eruptive events occur, including pyroclastic explosions, hot ash releases, lava flows, gas emissions, and glowing avalanches (gas and ash releases). Lava flows tend not to result in high casualties, because they are easily avoidable. The “composite” type of volcano is associated with a more violent eruption from within the chimney. These eruptions are associated with air shock waves, rock projectiles (some with high thermal energy), release of noxious gases, pyroclastic flows, and mud flows (lahars). Pyroclastic flows and lahars are often fast moving and are the main cause of damage and deaths from volcanoes, as evidenced by the small eruption of the Nevado del Ruiz in Columbia that killed more than 23,000 people.²⁶ The release of ash and its subsequent rapid buildup on building structures can be substantial, causing them to collapse within a matter of hours. Ash is also responsible for the clogging of filters and machinery, causing electrical storms and fires, and interfering with communications. Ash is a main cause for respiratory-related syndromes and conjunctival and corneal injury. A variety of toxic gases (e.g., carbon dioxide, hydrogen sulfide, sulfur dioxide, hydrogen chloride, hydrogen fluoride, and carbon monoxide [CO]) are released during eruptions, causing bronchospasm, pulmonary edema, hypoxemia, cellular asphyxiation, topical irritation of skin and other mucosal surfaces, and death.²⁷ Damage to health infrastructures and water systems can be severe. Problems related to communication (ashes cause serious interference) and transportation (poor visibility and slippery roads) are likely. Depending on the initial assessment, various needs can be anticipated. Reducing the risk for vulnerable groups of being exposed to ash, raising awareness of the risk associated with ash (health and mechanical risk), and maintaining food security conditions over the long term (lava, ash, and acid rain cause damage to crops and livestock) can help minimize suffering.²⁸

Hurricanes, Cyclones, and Typhoons

The large rotating weather systems that form seasonally over tropical oceans are variously named, depending on the geographic region where they form.^29–31 They consist of a calm inner portion called the eye, surrounded by a wall of rain and high-velocity winds. Based on central pressure, wind speed, storm surge, and potential destruction, their severity is graded on a scale of 1 to 5 (Saffir Simpson scale).³⁰ They are among the most destructive natural phenomena. Cyclones during 1970 and 1991 in Bangladesh claimed 300,000 and 100,000 lives, respectively, due to flooding.³² The most devastating hurricane ever to hit the United States was in 1900 at Galveston, Texas. It claimed an estimated 8000 to 12,000 lives.³³ The greatest damage to life and property is not from the wind but from secondary events such as storm surges, flooding, landslides, and tornadoes. Ninety percent of all hurricane-related deaths occur from storm surge–related drowning.¹ The most common injury patterns include lacerations (during the cleanup phase), followed by blunt trauma and puncture wounds. Late morbidity can be due to post-disaster cleanup accidents (e.g., electrocution), dehydration, wound infection, and outbreaks of communicable disease.^31,34 Data from hurricane Katrina confirmed data from previous meteorological events: the leading mechanisms of injuries are fall, lacerations, and piercing injuries, with cleanup being the primary activity at the time of injury.³⁵ Recent experiences in the aftermath of hurricane Katrina in 2005 indicate that resources may have to be provided for an extended period after the initial inciting event, and that significant resources may have to be provided for patients with chronic medical illnesses.^34,36

Floods

There are three major types of floods: flash floods (caused by heavy rain and dam failures), coastal floods, and river floods. Together, they are the most common type of disasters and account for at least half of all disaster-related deaths.^37,38 The primary cause of death is drowning, followed by hypothermia and injury due to floating debris.^39,40 The impact on the health infrastructures and lifeline systems can be massive and may result in food shortages. Interruption of basic public services (e.g., sanitation, drinking water, electricity) may result in outbreaks of communicable disease.^38,40 Another concern is the increase in both vectorborne diseases (e.g., malaria, St. Louis encephalitis) and displacement of wildlife (e.g., poisonous snakes and rodents).^39,40

Landslides

Landslides are more widespread than any other geologic event. They are defined as downslope transport of soil and rock resulting from natural phenomena or manmade actions. Landslides can also occur secondary to heavy storms, volcanic eruptions, and earthquakes. Landslides cause high mortality and few injuries. Trauma and suffocation by entrapment are common. Pending an assessment, needs can be anticipated, such as search and rescue, mass casualty management, and emergency shelter for the homeless.^41,42

Pandemic 2009 H1N1 Influenza a Virus

Pandemic H1N1 2009 is a new strain of influenza A virus that was first identified in Mexico and the United States on March 18 and April 15, 2009, respectively. It originated from the quadruple reassortment swine influenza (H1N1) virus closely related to the North American and Eurasian swine lineage. However, this new virus circulated only in humans, with no evidence of transmission between humans and animals.

Within weeks, the virus quickly spread worldwide through human-to-human transmission. On April 26, 2009, the CDC’s Strategic National Stockpile began releasing 25% of the supplies in the stockpile for the treatment and protection from influenza.⁴³ On June 11, 2009, the World Health Organization (WHO) declared the 2009 H1N1 influenza a global pandemic, generating the first influenza pandemic of the 21st century, with more than 70 countries reporting cases of H1N1 infection. By June 19, 2009, all 50 states in the United States, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands had reported cases of 2009 H1N1 infection. More strikingly, the Centers for Disease Control and Prevention (CDC) Emerging Infections Program (EIP) estimated the number of hospitalizations and deaths in people 64 years and younger. The virus was most likely to strike children, young adults, and those with underlying pulmonary and cardiac disease. Pregnant women in their second and third trimester were also at high risk. Patients requiring intensive care had a remarkable prevalence of obesity.⁴³

Influenza vaccines are most effective not only to prevent but also to mitigate the severity of illness. The pandemic H1N1 influenza vaccine was promptly developed by the WHO and national authorities. A national influenza vaccination campaign was launched in the United States in October 2009, and the first H1N1 vaccine was made available at that time. Despite the rapid response of the authorities, developing countries in the Southern Hemisphere experienced delays and shortages of the vaccines. Thus, recent research and developmental work have been encouraging for developing a “universal” influenza vaccine that could provide efficacious cross-reactive immunity and induce broad protection against different variants and subtypes of the influenza virus.⁴⁴

To date, the preliminary data show that about 8% of H1N1 patients were hospitalized (23 per 100,000 population); 6.5% to 25% of these required being in the ICU (28.7 per million inhabitants) for a median of 7 to 12 days, with a peak bed occupancy of 6.3 to 10.6 per million inhabitants; 65% to 97% of ICU patients required mechanical ventilation, with median ventilator duration in survivors of 7 to 15 days; 5% to 22% required renal replacement therapy; and 28-day ICU mortality was 14% to 40%.^45–51

Critical care capacity is a key element of hospital surge capacity planning.¹⁰ The proportion of ICU beds occupied by patients with H1N1 varied. In Australia and New Zealand, it peaked at 19%⁷ while in Mexico, many patients required mechanical ventilation outside the ICUs.⁶ To match the surge capacity with increasing ICU demands during a pandemic is a difficult task, since uncertainty exists for many of these parameters. The disease brought a surge of not only critically ill patients but patients who required prolonged mechanical ventilation and ICU management. Hospitals should maximize the number of ICU beds by expanding ICUs and other areas with appropriate beds and monitors. Elective procedures should be minimized when resources are limited, and critical care capacity should be augmented.

Safe practices and safe respiratory equipment are needed to minimize aerosol generation when caring for patients with influenza. These measures include handwashing and wearing gloves and gowns. The use of N95 respirators reduces the transmission of epidemic respiratory viruses. Staff training in personal protective equipment use is essential. Use of bag-mask ventilation and disconnection of the ventilator circuit should be minimized. Moreover, the use of heated humidifiers on ventilators, Venturi masks, and nebulized medications should be avoided.⁵²

When the number of critically ill patients far exceeds a hospital’s traditional critical care capacity, modified standards of critical care to provide limited but high-yield critical care interventions should be the goal in order to accommodate far more patients. Triage criteria should be objective, transparent, and ethical and be applied justifiably and publicly disclosed. The ICU triage protocols for pandemics should only be triggered when ICU resources across a broad geographic area are or will be overwhelmed despite all reasonable efforts to extend resources or obtain additional resources.⁵³ The Sequential Organ Failure Assessment (SOFA) score, though not validated, has been proposed to determine qualification for ICU admission during mass critical care.

The major characteristics of 2009 H1N1 influenza A infection were the rapidly progressive lower respiratory tract disease leading to acute respiratory distress syndrome (ARDS) with refractory hypoxemia. A substantial number of H1N1 ICU patients required advanced ventilatory support (ranging from 1.7% to 11.9%) and rescue therapies including high levels of inspired oxygen and positive end-expiratory pressure (PEEP), inverse ratio ventilation, airway pressure release ventilation (APRV), neuromuscular blockade, inhaled nitric oxide, high-frequency oscillatory ventilation (HFOV), extracorporeal membrane oxygenation (ECMO), volumetric diffusive respiration, and prone-positioning ventilation.^46,49,51,54 Of particular interest was the successful use of ECMO in the management of refractory hypoxemia in these patients in two studies. The median durations of therapy and survival rates to ICU discharge were 10 days and 15 days—71% and 67%, respectively.^55,56

As of March 13, 2010, the CDC estimates of 2009 H1N1 influenza cases, hospitalizations, and deaths in the United States since April 2009 were 60 million cases, 270,000 hospitalizations, and 12,270 H1N1-related deaths, respectively.⁵⁷ The virus did not mutate during the pandemic to a more lethal form. Widespread resistance to oseltamivir did not develop. The WHO declared an end to the H1N1 pandemic on Aug 10, 2010. According to Margaret Chan, the Director-General of the WHO, the H1N1 virus is no longer the dominant circulating virus worldwide. Based on the available evidence and experience from past pandemics, “it is likely that the virus will continue to cause serious disease in the younger age group, at least in the immediate post-pandemic period. The H1N1 virus is expected to take on the behavior of a seasonal influenza virus and to circulate for some years.”

Other Natural Disasters

Tornadoes occur most commonly in the North American Midwest. Over 4115 deaths and 70,000 injuries have been ascribed to them during the years 1950 to 1994. They cause widespread destruction of community infrastructure. Injuries most commonly seen are complex contaminated soft-tissue injury (50%), fractures (30%), head injury (10%), and blunt trauma to the chest and abdomen (10%).^58,59 Firestorms, wildfires, tsunamis, winter storms, and heat waves are other natural phenomena capable of creating mass injuries from thermal burns, airway injury, smoke inhalation, heat-related disorders, and hypothermia.^60–63

Transportation Disasters

Transportation accidents can produce injuries and death similar to those seen in major natural disasters. Some of the largest civilian disasters in North America have been related to transportation of hazardous materials.⁶⁴ Motor vehicle accidents, railway accidents, airplane crashes, and shipwrecks are some of the common transportation accidents. They cause a wide range of injuries including multiple trauma, fractures, burns, chemical injuries, hypothermia, dehydration, asphyxiation, and CO inhalation. The hazard risk to a healthcare facility increases with its proximity to a chemical plant or highway, and such factors should be considered in the emergency preparedness plan of the hospital.⁶⁵

Weapons of Mass Destruction

Weapons of mass destruction (WMD) are those nuclear, biological, chemical, incendiary, or conventional explosive agents that pose a potential threat to health, safety, food supply, property, or the environment. Since the devastating terrorist attacks in September 2001 and subsequent intentional release of anthrax spores in the United States, there is growing concern around the world about the possible threat of chemical, biological, or nuclear weapons used against a civilian population. Compared with the frequency of natural and technology-related disasters, the incidence of use of WMD to cause death and injury is relatively rare. However, biological and chemical weapons are relatively accessible, and WMD are thought to be available to most foreign states and terrorist groups. In response to a WMD incident, healthcare personnel will be called on to manage unprecedented numbers of casualties in an environment of panic, fear, and paranoia that accompanies terrorism. Because most attacks occur without warning, the local healthcare system will be the first and most critical interface for detection, notification, rapid diagnosis, and treatment. The best defense in reducing casualties will therefore rest on the ability of medical and public health personnel to recognize symptoms and provide rapid clinical and epidemiologic diagnosis of an event. This requires that healthcare providers be well informed of potential biological, chemical, and nuclear agents. They must have a heightened index of suspicion and be able to identify unusual disease patterns to determine whether WMD are the etiologic agents of illness. Physicians will need to practice appropriate surveillance and reporting and develop knowledge of mass decontamination, use of proper personal protection equipment, and safety protocols related to a biological, chemical, or radiologic event.^66–68 Salient characteristics and brief management strategies of the different WMD are discussed here. Detailed description of individual biological and chemical agents, diagnosis, postexposure management, vaccination, infection control measures, and use of personal protection equipment is beyond the scope of this chapter.

Blast Injuries

Bombs contain an array of compounds such as nitroglycerin, trinitrotoluene, and others that are encased in a metal or plastic case. Decomposition of the solid or liquid compound into gas leads to massive dissipation of energy and pressure creating a blast wave (shock wave). This destructive effect can be increased by the presence of nuts, nails, and bolts in the casing. Water transmits blast waves more efficiently than air, with the greatest impact being on structures that are the deepest.⁸³ There are four types of blast injuries:

The most common injuries associated with fatality in blast incidents include subarachnoid hemorrhage (66%), fracture of the skull (51%), lung contusion (47%), tympanic membrane rupture (45%), and liver laceration (34%). Unfortunately, the extent of the blast injury cannot be assessed during the course of rapid triage examinations. In the absence of overt trauma, a focused physical examination should include examination for ruptured tympanic membrane, hypopharyngeal contusions, hemoptysis, and auscultation for wheezing. The presence of a ruptured tympanic membrane is almost always an indicator that the patient has been exposed to a blast wave powerful enough to cause serious damage. The thorax is frequently involved in a blast injury, manifesting with wheezing, hemoptysis, pneumothorax, hemothorax, and air embolism. Patients may have myocardial contusion as well. The presentation of serious pulmonary injury may be delayed. Pulmonary barotrauma is the most common fatal primary blast injury. Patients with nonpenetrating lung injury will likely have hypoxia requiring support ranging from oxygen therapy to mechanical ventilation. This may result from pulmonary contusion, systemic air embolism, and disseminated intravascular coagulation. Acute gas embolism, a form of pulmonary barotrauma, is also associated with blast injuries. Air emboli most commonly occlude blood vessels in the brain or spinal cord, resulting in neurologic symptoms that must be differentiated from the direct effect of trauma. Patients thought to have gas embolism require decompression treatment. Administration of 100% oxygen by tight-fitting facemask and left lateral recumbent position may help. Definitive treatment is with the use of hyperbaric oxygen. Patients with blast injury of the lung are likely to present with abdominal injuries that are usually more delayed. These include delayed bowel perforation and liver lacerations. The former may warrant exploratory laparotomy.^84–87

Blast victims receiving general anesthesia have an increased mortality rate; other forms of local and spinal anesthesia are preferred, and general anesthesia should be deferred if possible for 24 to 48 hours. Intensivists should be aware of the increased need for resuscitation equipment, ventilators, and movement in and out of the operating room during such situations.

All patients with significant burns, suspected air embolism, radiation or white phosphorus contamination, abdominal signs of contusion/hematoma, or clinical evidence of pulmonary contusion or pneumothorax should be admitted to the hospital. Patients with tympanic membrane rupture and suspected pneumothorax should get some form of chest imaging, and a significant observation period may be warranted. Other investigations must be judiciously ordered, keeping in mind the limited availability of resources in a mass-casualty incident. Screening urinalysis for presence of hematuria, tests for CO poisoning (explosion in a closed space or associated with fire) and cyanide toxicity (due to combustion of plastics), and assessment of acid-base status may be indicated. Use of abdominal computed tomography to rule out intestinal hematomas is not routinely warranted and should be dictated by clinical signs and symptoms. Pregnant patients with blast injuries warrant special consideration, and appropriate consultation is necessary to rule out blast injury to the fetus.⁸⁵ Supplemental oxygen therapy, maintaining spontaneous respiration, and low PEEP (if mechanical ventilation is required) are some of the guiding principles in managing pulmonary blast injuries. Routine corticosteroids and antibiotics are not warranted. Exposure to white phosphorus explosives (e.g., in hand grenades) deserves special mention. Use of a Wood’s light in a darkened resuscitation suite or operating room may help identify white phosphorus light particles in the wound. White phosphorus injury can cause lung injury through irritation, as well as severe hypokalemia and hyperphosphatemia with cardiac arrhythmias and death. External burns should be lavaged with 1% copper sulfate solution. This forms a blue-black cupric phosphide coating and prevents combustion so that the particles can safely be removed.⁸⁸

Crush Injury Syndrome

Crush injury syndrome refers to systemic manifestations of extensive muscle damage caused by entrapment of victims under collapsed buildings or debris. Reported incidence depends on the type of disaster, ranging from 2% to 40%. Metabolic alterations from the release of muscle constituents into the circulation include myoglobinemia leading to acute renal failure, hyperkalemia, hyperphosphatemia, and disseminated intravascular coagulation. Increased intracellular calcium concentrations appear to be the final common pathway. Muscle damage that occurs is due not only to direct crush injury but also to vascular injury and insufficiency leading to altered compartment pressures and reperfusion injury. Inelastic fascial sheaths encase skeletal muscles in the forearm and lower leg and are particularly vulnerable to dramatic increases in compartment pressures, resulting in compartment syndrome. An intracompartmental pressure in excess of 40 mm Hg lasting longer than 8 hours defines this syndrome. Pressures as high as 240 mm Hg can be seen with crush injuries. Compartment syndromes are seen with limb fractures, use of military antishock trousers, pneumatic splints, vascular injuries, and crush injuries. The affected limb may present with severe pain associated with passive stretch or extension, flaccid paralysis, and sensory loss. Capillary refill and peripheral pulses are usually present unless the compartmental pressure equals the diastolic pressure. Diagnosis requires a high degree of clinical suspicion and entails prompt bedside measurement of compartmental pressures. A simple and easy method that can be performed in the hospital or field hospital is using an 18-gauge needle attached to a mercury manometer. In an ICU, pressure transducers used to measure central venous pressures can be attached to the 18-gauge needle to obtain the same information.⁸⁹

Resuscitation of patients with crush injury (any victim crushed or immobilized for more than 4 hours) should begin in the field. After adequate intravenous access is achieved, isotonic fluid replacement with normal saline (rate of 1-1.5 L/h) should begin even before extrication of the crushed limb. If fluid therapy is delayed, the incidence of renal failure increases to 50%; delays of 12 hours are associated with a 100% incidence. Occurrence of renal failure is associated with a 20% to 40% mortality rate. Urinary alkalinization with sodium bicarbonate and mannitol or acetazolamide administration are used to maintain urine pH greater than 7.5. Although this intervention is widely used, there are no prospective randomized controlled trials to support it. Dialysis may be indicated if aggressive fluid resuscitation fails, and this may create a huge demand for dialysis machines in disaster situations. Peritoneal dialysis if the abdomen is intact and continuous arteriovenous hemofiltration may be other useful options. The latter option, however, is complicated by hemorrhagic problems related to the use of heparin and immobilization. Life-threatening infections are common after crush injuries and may be increased in the presence of a fasciotomy. In unsalvageable limbs, it may be advisable to perform on-field amputations to avoid the systemic effects of a crush injury syndrome. For this purpose, ketamine is the anesthetic and analgesic of choice because of its safety profile in the field.⁸⁹

Particulate Health Problems

Many disasters result in release of copious particulate matter, causing a wide spectrum of respiratory illnesses including cough, wheezing, smoke inhalation injury, reactive airways disease, and ARDS. Volcanic eruptions with associated pyroclastic flows and ash fall are some of the most devastating producers of particulate matter. Mortality in these situations arises from suffocation by ash in the upper airways, ARDS, and inhalation burns. The massive building collapse and fires associated with the 2001 World Trade Center terrorist attack caused significant pulmonary complaints among rescue personnel.⁹⁰

Smoke inhalation injury resulting from exposure to noxious products of combustion in fires may account for as many as 75% of fire-related deaths in the United States. The three primary mechanisms that lead to injury in smoke inhalation are thermal damage, asphyxiation, and pulmonary irritation. Combustion utilizes oxygen in the airways and causes a decrease in fraction of inspired oxygen, leading to hypoxemia. Increased CO levels decrease the oxygen-carrying capacity of the blood and cause myocardial depression. Combustion of plastics, polyurethane, wool, silk, nylon, rubber, and paper products can lead to the production of cyanide gas, resulting in anaerobic metabolism and decreased oxygen consumption. Rarely, we may also find methemoglobinemia, which reduces oxygen-carrying capacity.⁹¹

Mortality rate with smoke inhalation alone is about 10% but increases to about 77% in the presence of major burns or respiratory failure. Early deaths are mostly caused by airway compromise or metabolic poisoning. Laboratory workup should include co-oximetry; CO, methemoglobin, and cyanide levels (if there is discordance in measured saturation and pulse oximetry readings); blood lactate levels (a level greater than 10 mmol/L that is refractory to restoration of adequate ventilation, oxygenation, and perfusion is considered a surrogate marker of cyanide toxicity) on blood gases; and a calculated alveolar-arterial pressure gradient. Initial blood gas measurements and chest radiograph may be normal. Carboxyhemoglobin level obtained in the emergency department does not correlate with tissue hypoxia or long-term neurologic sequelae; ideally, a carboxyhemoglobin level at the scene would be most valuable.

Serial bronchoscopy is indicated in the first 18 to 24 hours to assess airway edema and sloughing. Early bronchoscopy can be of diagnostic and therapeutic value, particularly when lobar atelectasis is present. High-flow humidified oxygen is critical to reverse or prevent hypoxemia. About 50% of patients with an inhalation injury require tracheal intubation, and this number increases in patients who have burn injuries. The need for tracheal intubation is determined by the need to maintain airway patency and pulmonary toilet and to provide positive-pressure ventilation. Positive-pressure ventilation with PEEP increases short-term survival and is associated with decreased tracheobronchial cast formation. Cyanide toxicity (levels > 0.1 mg/L) should be promptly treated using a USA cyanide kit. Recommendations for the use of hyperbaric oxygen in the setting of CO poisoning include CO levels greater than 25% to 30%, neurologic compromise, metabolic acidosis, or electrocardiographic evidence of myocardial ischemia, infarction, or dysrhythmias. Hyperbaric oxygen has been used in cyanide toxicity but has not been proven effective. The role of corticosteroids is controversial, and they can be detrimental if given in the presence of cutaneous burns. Empirically administered antibiotics are another issue in dispute. Common pitfalls in the initial management of smoke inhalation are using initial PaO₂ to predict adequacy of oxygenation, placing small-diameter nasotracheal tubes, intubating without applying PEEP, and restricting fluids for concomitant inhalation and burn injury.^91,92 General measures that could be employed in a field setting include simple airway protection by clearing any particulate matter in the airway, supplemental oxygen, and nebulizer treatment if available. Patients with preexisting asthma and emphysema should be observed for exacerbations.

Acute Radiation Syndrome

Ionizing radiation can be either charged or uncharged particles (photons). Beta particles are capable of penetrating a few centimeters of tissue. Gamma rays and x-rays are capable of penetrating through tissue and concrete. Gamma, x-ray, and beta radiations are considered low linear energy transfer radiation. Alpha particles have no penetrating power past the keratinized layer of skin, but they take on clinical significance if they are internalized by ingestion or inhalation. Neutron emission (e.g., from nuclear reactors, nuclear devices, and industrial moisture detectors) is highly potent radiation that penetrates deep and creates denser ionization trails. Alpha and neutron emissions are considered high linear energy transfer radiation and have significantly more biological effects than low linear energy transfer radiation by a factor of up to 20. When the process of ionization occurs within living tissue it causes breakage in the chemical bonds, and the most susceptible target is the cellular DNA. This leads to impaired mitosis and subsequent organ failure. Large doses of radiation are generally considered to cause more biological destruction than fractionated doses. Systemic radiation illness and lethality from it can result from as little as 450 rad. Precise measurements of the amount of radiation following a nuclear accident will be delayed. Hospital gamma cameras are an invaluable resource for helping determine the exposure in an individual. Higher systemic doses are suggested by shorter onset of prodromal symptoms such as nausea, vomiting, and diarrhea. Serial absolute lymphocyte counts will screen those patients who have psychogenic vomiting. Acute radiation syndrome has four distinct phases^67,78,80:

For radiation syndrome to occur, radiation must be of the penetrating type in a sufficiently large dose (>0.7 Gy), must be external, and must occur within a short time period. The disease complex has three syndromes: bone marrow, gastrointestinal, and cardiovascular/central nervous system. Serial absolute lymphocyte counts should be measured immediately on suspicion of exposure (every 3 hours), because lymphocytes are among the most radiosensitive cells and reach nadir within 2 days; platelets reach nadir in 15 to 30 days; and neutrophils at about 30 days. Patients are immunocompromised and susceptible to a wide variety of infections, that of most concern to the intensivist being septic shock. Gastrointestinal syndrome leads to mucosal sloughing, decreased nutrient absorption, and translocation of bacteria and endotoxin. Veno-occlusive disease may also develop if the dose is large enough. Cardiovascular and central nervous system disease develop with doses greater than 5000 rad, and death can occur in as little as 3 days from myocarditis, capillary leak, pulmonary edema, and brain edema. Pneumonitis and subsequent fibrosis can lead to respiratory failure and the need for ventilator support. Treatment of ARS is mainly supportive. If internal contamination is thought to have occurred, enhancement of excretion and specific antidote therapy are warranted. For inhalational contamination, bronchoalveolar lavage may be necessary; and for ingestion, gastric lavage and purgative management are warranted. Plutonium and transuranic elements can be treated with chelating agents such as calcium or zinc diethylenetriamine pentaacetic acid. Radiocesium can be treated with Prussian blue, which helps enhance excretion in feces. Radioiodine exposure can be treated with potassium iodide. Uranium excretion can be enhanced by the alkalinization of urine and with potassium supplementation.

Psychological Trauma

The psychological component in a traumatic event is often overlooked, with the major focus usually being on physical health issues. Studies evaluating the emotional impact from disasters indicate that a majority of victims, first responders, and mortuary volunteers will suffer some form of psychological trauma. Intensivists should be aware that behavioral changes may not be only due to the catastrophic insult but also due to organic causes such as head injury, inability to take predisaster psychiatric medications, and toxin or chemical exposure. Groups at risk, such as children, adolescents, and victims who have been exposed to traumatic stressors of bereavement, witnessing death, and situations evoking guilt, fear, or anger, should receive prompt psychiatric and posttraumatic counseling. Interventions such as debriefing, eye movement desensitization and reprocessing, and critical incident stress management may help minimize emotional suffering and morbidity.⁹³

Other Syndromes

Burns, blunt trauma, intraabdominal injury, head injuries, penetrating trauma, and hypothermia are some of the other disaster syndromes encountered in the field. Specific discussion of these entities is beyond the scope of this chapter, and the reader is referred to other chapters for management details.⁵

Common Issues and Misconceptions in Disaster Planning

Typically, the hospital nearest to the disaster site will receive the bulk of the casualties. It is thus important to conduct a careful survey of a disaster plan’s jurisdiction to identify potential sites (i.e., industries, nuclear reactors, highways) and likely types of hazardous events that could occur in the area. Hospitals in the nearby area receive few disaster victims, and an average have at least 20% of their beds vacant. Disaster plans would thus need to include transfer agreements between hospitals and nearby ICUs to meet bed shortages by activating the National Disaster Medical System Hospital Activation System.^79,94,95

Very few casualties actually require hospital admission. A study of 29 mass-casualty incidents found that less than 10% of casualties required overnight admission under usual criteria (even though more were admitted because they were involved in the disaster rather than because of severity of their condition). Large numbers of casualties with minor conditions will appear at the nearest hospitals, often on foot or in private vehicles, police cars, buses, taxis, and other non-ambulance forms of transport. Field triage stations are often bypassed, and this in turn causes enormous strain on the emergency department services.⁹⁶

Most of the logistical problems faced in disaster situations are not caused by shortages of medical resources but rather from failure to coordinate their distribution.⁹⁴ Inexperienced volunteers may not be familiar with the triage system or principles of personal safety, and massive numbers of volunteers can present serious administrative challenges. This results in disorganization and inefficiency.⁸¹ Technical hazard sheets designed by the WHO for most disasters also suggest that medical personnel, blood donors, and blood products should not be sent empirically to a disaster site.⁹⁷

Principles in Disaster Planning

Mobile ICU Teams

There have been numerous examples in medical literature describing extended critical care through mobile ICU teams. The use of mobile ICU teams has not been restricted to disaster settings but has also been used throughout the world during peacetime. Various factors that have to be considered in the formation of ICU teams are discussed next.

Types of Transport