Cold Shock Response

On-Scene Rescue and Patient Management

Hypothermia may offer a protective benefit and prolong the time after which resuscitation can still be successful. There are case reports in which patients survived after 40 minutes of submersion in cold water with complete or nearly complete neurologic recovery. Rescue attempts must always take into consideration the safety of rescuers to avoid creating additional victims. General guidelines for rescue and patient management are as follows:

The Asymptomatic Patient: Grades 0 and 1

Patients who have been rescued from the water and who are alert, with a clear chest examination to auscultation, no respiratory distress, and with or without coughing may not need further medical care but still present a dilemma. Patients may leave the scene only to suffer complications later that are caused by acute lung injury. Any person with shortness of breath may have mild hypoxemia and should be treated as a symptomatic patient. Patients who are treated and released at the scene should be advised that respiratory symptoms can develop up to 24 hours later and should seek emergency treatment immediately after the development of such symptoms.

Hypothermia is often difficult to ascertain at the scene, so it may be prudent to have the person evaluated, even if only briefly, at a medical facility. Conscious and cooperative patients should be protected against hypothermia with passive warming techniques, protected from the wind, and offered dry clothes and blankets. If the person remains asymptomatic with normal vital signs and stable arterial oxygen saturation (if testing is available) on ambient air for 10 to 15 minutes, then it is likely that he or she will not require further medical care.

The Symptomatic Patient: Grades 2, 3, and 4

All submersion patients requiring intervention or resuscitation or showing signs of distress (e.g., anxiety, tachypnea, dyspnea, syncope, persistent cough, presence of foam in the mouth or nose, changes in vital signs) should be evacuated or transported to a hospital or another health care facility for evaluation.

Protection of the airway to ensure oxygenation and ventilation is the first priority. Maintaining perfusion to reverse the metabolic consequences of acidosis is a close second. The airway should be protected from aspiration by placing the patient in a lateral recumbent (i.e., recovery) position if possible. Vomiting is common with submersion incidents, and aspiration can worsen lung injury. Measures should be taken to prevent hypothermia and shivering. Rescuers must maintain vigilance and treat cardiac dysrhythmias that may arise as a result of hypoxemia. The management actions listed in Table 50-1 can then be considered. If cervical spine injury is suspected, use an extrication collar and an immobilization device. Routine cervical spine immobilization is unnecessary and should be reserved for patients with a known or suspected significant mechanism of injury.

The Patient in Respiratory or Cardiopulmonary Arrest: Grades 5 and 6

Initiation of immediate ventilatory support and early CPR, if indicated, results in a better prognosis and outcomes. Initiation of chest compressions while the patient remains in the water is ineffective, delays extrication, and may further endanger the patient and rescuer. Alternatively, rescue breathing should be initiated as soon as the subject’s airway can be opened, even if in the water (see Fig. 50-3).

When the individual is out of the water, supplemental oxygen should be initiated as soon as possible. If the patient is spontaneously breathing, and a nonrebreathing mask, portable positive end-expiratory pressure (PEEP) valve, or portable continuous positive airway pressure (CPAP) device is available, oxygen should be delivered at a high flow rate (i.e., 10 to 15 L/min). A CPAP mask should be used cautiously if there is any concern about vomiting or loss of airway protective reflexes.

Maneuvers to empty the lungs of fluid, including abdominal thrusts, are not recommended. Gastric distention can interfere with ventilation by increasing intra-abdominal pressure. In such instances, gastric decompression by nasogastric tube is recommended. Digital or visual examination for foreign bodies should be done, and if foreign bodies are present, they should be removed with a swipe or grasp of the fingers.

Should vomiting occur, roll the patient onto his or her side or turn his or her head to the side and remove the vomitus with a cloth or finger-sweep maneuver. If spinal injury is of concern, the patient should be logrolled, maintaining linear alignment of the head, neck, and torso. Because most beaches, riverbanks, boat ramps, and other waterway access points are sloped, patients should be placed perpendicular to the incline so that head and feet are level. When the subject is out of the water and airway and breathing are addressed, the presence or absence of adequate circulation should be ascertained. In cases of hypothermia or hypotension a pulse may be difficult to identify. If ventilation or cardiac function is impaired, chest compressions should be initiated as soon as the patient is removed from the water. For patients who are more than 1 year old, an automated external defibrillator may be used to evaluate heart rhythm. If the field rescue team is capable of advanced life support, cardiac monitoring, and intravenous or intraosseous access, fluids and medications should be administered according to advanced life support protocols. Basic life support or advanced cardiac life support should continue until the patient’s core body temperature is more than 30° C (86° F). See Table 50-1 for a classification scheme for drowning field assessment and management.

Prognosis and Termination of Resuscitation

Declaring a patient dead from drowning is complicated by the fact that many of the most dramatic and physiologically unexpected recoveries from cardiac arrest have been in young patients after cold-water drowning. The duration of submersion, water temperature, patient core body temperature, and any cardiac electrical or echocardiographic activity should be considered before the declaration of death. If there is any uncertainty, then resuscitation should be continued until the patient is rewarmed to 30° to 35° C (86° to 95° F). Functional recovery with minimal neurologic impairment occurs in approximately 17% of those who require resuscitation in the emergency department.

Factors known to be useful for predicting outcomes in drowning are listed in Box 50-1. In the absence of profound hypothermia, the neurologic status of a patient on admission to the emergency department is of paramount importance for predicting survival with intact neurologic function. Persons who are alert when admitted seldom die.