12 Selected Injuries Allan V. Abbott Unintentional injuries remain the fifth leading cause of death in the United States. Table 12.1 lists these deaths according to cause and fre- quency.1 Near-Drowning Drowning is the third leading cause of accidental death in the United States, accounting for about 4000 deaths annually. Near-drowning is defined as survival after an episode of suffocation and cerebral hypoxia in a liquid medium, whereas submersion injury (drowning) is death within 24 hours of such an episode. Secondary drowning is death from complications that occur more than 24 hours after the submersion. Immersion syndrome is sudden death after contact with cold water.2 Most near-drownings and drownings occur among inadequately supervised children younger than 4 years of age in swimming pools, ocean surf, bathtubs, or hot tubs. In small children, drowning is more common than toxic ingestions and firearm injuries. Boys and young men between the ages of 15 and 24 and the elderly over age 75, espe- cially if unable to swim, are also at risk because of alcohol or drug use while swimming, infirmity, or associated trauma or seizures. Clinical Presentation The usual submerged drowning victim at first holds his or her breath and becomes anoxic and panics, then swallows or gasps and aspirates water, loses consciousness, and dies in cardiac arrest. Approximately 10% of victims have acute laryngospasm that results in dry drowning, 262 Allan V. Abbott Table 12.1. Deaths Due to Unintentional Injuries—United States, 19991 Type of injury Deaths per year All unintentional injuries 96,900 Motor vehicle accidents 41,300 Falls 17,100 Drowning 4,000 Suffocation by ingested object 3,200 Fires and burns 3,100 Firearms 700 Poisoning by gas and vapors 500 All other 16,500 because there is no aspiration of water into the lungs and death typi- cally occurs owing to profound obstructive asphyxia.2 The duration of hypoxia that can be tolerated depends on the indi- vidual’s age and health, the water temperature, and the promptness and effectiveness of the resuscitation. Young victims usually recover if the submersion is less than 3 minutes, or up to 10 minutes if the water is cold (0°–15°C) (32°–59°F). Survival has been reported after 15 to 20 minutes of submersion and up to 40 minutes in cold water.3 With near-drowning the clinical presentation depends on the stage at which the drowning sequence was interrupted. Aspiration of water leads to varying degrees of pulmonary edema and can result in adult respiratory distress syndrome as late as 72 hours after the near-drowning. There may be shortness of breath, rales, rhonchi, or wheezing. Chest radiographs may initially show pulmonary edema or appear mislead- ingly normal. Severe pulmonary edema can develop slowly in a patient who initially has no pulmonary signs or symptoms. Hypothermia due to submersion in cold water often leads to bradycardia or atrial fibrillation. Hypoxia leads to cerebral damage with subsequent cerebral edema. Internal injuries should be suspected with falls into the water and boat- ing accidents; cervical spine and head injuries are particularly common. Severe acidosis and electrolyte disturbances can occur. Subsequent intravascular hemolysis, disseminated intravascular coagulation, and renal failure are uncommon but possible. Management Immediate Management Aggressive emergency resuscitation is the most important factor influ- encing outcome.4 Airway protection and respiratory support should begin immediately, even before removal from the water. Advanced 12. Selected Injuries 263 cardiopulmonary life support (ACLS) is begun immediately as indi- cated by the circulatory status and cardiac rhythm. Maneuvers to pro- mote postural drainage, such as that advocated by Heimlich et al,5 are controversial, with most experts discouraging their use because of interruption of cardiopulmonary resuscitation, loss of airway control, aspiration, and aggravation of possible cervical spine injuries.6 Oxygen at 100% is administered to all near-drowning victims as soon it is available. Hospital Management The initial appearance of near-drowning patients who are conscious may be deceptively normal. Therefore, virtually all near-drowning patients should be admitted for observation, oxygen, and supportive care. If they remain asymptomatic and if chest films and arterial blood gas assays remain normal, they may be discharged after 8 hours, or after 24 hours if there was any aspiration. A large-bore intravenous line should be positioned. The rectal temperature is measured; and if the patient is hypothermic (Ͻ35°C, Ͻ95°F), rewarming is begun. Most serious cases are reflected in lactic acidosis and electrolyte disturbances, and treatment is guided by monitoring the arterial blood gases and serum electrolytes. Patients are monitored for respiratory and central nervous system (CNS) function. Indications for endotracheal intubation in hospital- ized patients include (1) protection of the airway in nearly comatose patients, (2) neurologic deterioration, (3) copious secretions or gross aspiration of particulate matter, and (4) inability to maintain a PaO2 of 60 to 90 mm Hg. Positive end-expiratory pressure (PEEP) is helpful with a pulmonary injury to recruit gas exchange in spaces and to pre- vent terminal airway closure. A nasogastric tube is placed to remove excess swallowed water and air. Bronchospasm can be managed with ␤-adrenergic aerosols. Early therapeutic bronchoscopy should be considered if particulate matter such as vomitus or mud have been aspirated. Most centers currently employ supportive care and do not use prophylactic antibiotics, bar- biturates, steroids, hypothermia, hyperventilation, intracranial pres- sure monitoring, or neuromuscular blockade routinely.2 Survival after near-drowning and cerebral anoxia can be predicted by neurological examination 24 hours after the drowning incident. The absence of spontaneous, purposeful movements and normal brainstem function after 24 hours suggests severe neurologic deficits or death. Satisfactory recovery can be expected in presence of spon- taneous, purposeful movements and normal brainstem function.6 264 Allan V. Abbott Children who are involved in bathtub near-drownings may have suffered from abuse or neglect. In these cases the medical evaluation should include a social work consultation and a search for accompa- nying injuries.7 Prevention Physicians should counsel parents that most drownings of small children can be prevented if pools and hot tubs are surrounded by a fence of at least 55 inches in height with locked or self-closing, self-latching gates, if pool safety covers are in place, and if house door-opening alarms are used.3 Adults should provide immediate supervision at all times when children have access to pools. Children should always wear life jackets while in boats. Adults should be trained in basic cardiopul- monary resuscitation. Also, swimming must be avoided while under the influence of alcohol or psychoactive drugs. Barotrauma Barotrauma—injury caused by barometric pressure changes— usually results from diving under water, ascending into the atmosphere, or mechanical respiratory support. As one ascends into the atmosphere, the atmospheric pressure decreases gradually; at 5500 m (18,000 feet) it reaches a pressure of about one half that at sea level. In contrast, when one descends into water, the pressure of the water increases more rap- idly, with a doubling of pressure every 10 m (33 feet) below the surface. Barotrauma resulting from changes in atmospheric pressure occurs com- monly to the ear and sinuses. Among divers, barotrauma results in ear and sinus injuries, decompression sickness, and air embolism. Pulmonary barotrauma can result from diving or mechanical ventilation. Ear and Sinus Barotrauma Barotrauma can affect the external ear canal, middle ear, inner ear, and sinuses. It is sometimes referred to as the “squeeze” when the ambient pressures are greater than the pressures within the body cav- ities; it is called “reverse squeeze” under the opposite conditions. External Barotitis Ear canal squeeze occurs when divers descend with ear canals plugged with earplugs or cerumen. The diver experiences pain and 12. Selected Injuries 265 bloody drainage as the pressure in the middle ear exceeds that within the canal. On examination of the tympanic membrane, petechiae, hemorrhagic blebs, and rupture may be seen.8 Barotitis Media Barotitis media is the most common ear injury resulting from pressure. The eustachian tube provides the only route for air to enter or exit the middle ear. The normally functioning eustachian tube acts as a one-way valve, allowing excess pressures to vent passively from the middle ear while allowing air to enter only with active swallowing, yawning, or autoinflation (the patient holds nose and mouth shut, blows to puff cheeks, and swallows with cheeks puffed).8 When eustachian tube func- tion is impaired by mucosal inflammation due to upper respiratory infection (URI), allergy, or trauma, the active movement of air into the inner ear is usually impaired first, with passive venting being impaired later in more severe cases. Thus a person with a URI flying in an air- plane usually finds that ear pressures adjust on ascent, but pain increases during descent if swallowing or autoinflation maneuvers fail to “pop” the ears. Commercial airliners maintain cabin pressure equal to about 6000 to 8000 feet, so severe middle ear barotrauma is unlikely. Divers who do not achieve middle ear pressure equalization