Case Management Study: Cold-Water Immersion in a 22-Year-Old Service Member

Military Medicine, May 2006 by Harman, Kenneth R, Herndon, Thomas M

Cold-water immersion can include aspects of both hypothermia and near drowning. We present a case of a 22-year-old active duty service member who became a victim of cold-water immersion in Alaska. His rescue by the U.S. Coast Guard and subsequent treatment in a small community emergency room are reviewed using a case management format. Care of the cold-water immersion patient with limited resources is highlighted and the potential complications of cold-water immersion are emphasized. Disturbances in acid base balance, pulmonary function, and cardiac rhythm are discussed. Changes in some of the hematological indices seen in the cold-water immersion patient are reported for the first time.

Introduction

Cold-water immersion consists of aspects of hypothermia and near drowning. Hypothermia alone is the cause of approximately 600 deaths annually in the United States,1 while incidents of near drowning are estimated to be in the hundreds of thousands per year.2 The potential for cold-water immersion is a danger for individuals participating in recreational, commercial, and military activities in all but the warmest environments. Although extensive military operations over cold water are performed primarily by Navy, Marine, and Coast Guard personnel, cold-water exposure over land is a potential hazard for individuals serving in the Army and Air Force.3

We present a case of cold-water immersion, which occurred during the summer on the island of Kodiak, Alaska. This report includes a chronicle of U.S. Coast Guard rescue procedures during this case. The treatment of cold-water immersion in the field and in a community hospital setting is reviewed.

Case Report

A 22-year-old male active duty service member, new to Kodiak, Alaska, took advantage of an unusually warm day in May to practice kayaking on a local bay. The air was calm and ambient air temperature was 23�C (75�F). Water temperature was 10�C (50�F). Approximately one-half mile from shore, his kayak flipped over. He was able to egress without difficulty, but he did not know how to right the vessel. He was wearing a T-shirt, jeans, and life vest suspenders, which kept him upright. After 2 minutes in the water, he was unable to use his fingers and soon after, he could not effectively use his hands. He began yelling for help.

A man walking on a beach approximately 1 mile away heard the faint calls and used his cell phone to notify the U.S. Coast Guard Air Station, Kodiak. A U.S. Coast Guard HH60 Jayhawk helicopter on a routine training mission was diverted to the scene. The aircraft's rescue swimmer entered the water to assist the victim, who at that point had been in the water for approximately 25 minutes. The rescue swimmer found him face down in the water, obtunded but arousable. A basket was lowered and the patient was hoisted to the hovering aircraft. The rescue swimmer reported that the patient would not have been able to climb into the basket without help. The patient does not remember the events of his rescue. After hoisting, he was transported to an ambulance waiting on the road system nearby and transferred to the local community hospital.

I. At this point, what interventions are appropriate?

a. Remove wet garments

b. Maintain horizontal position

c. Avoid rough movements

d. Rub patient's extremities

e. Shake patient, if necessary, to prevent toss of consciousness

f. Cover patient with blankets

To prevent further conductive and convective heat loss from the wet and cold clothing and evaporative and radiant heat loss from the wind, wet garments were removed, the patient was kept in a horizontal position, and covered with blankets. This began the passive rewarming process. The patient was handled gently and shaking the patient was avoided to prevent the development of potentially life-threatening cardiac arrhythmias. Although rubbing the extremities can lead to rewarming to some extent, the subsequent vasodilatation of the vessels in the extremities shunts cold blood to the core, resulting in an overall further decrease in body temperature. This paradoxical drop in core body temperature when the extremities are rewarmed is known as the after-drop phenomenon.

Upon arrival at the emergency room, approximately 15 minutes later, the patient remained obtunded but arousable. He complained of being cold and thirsty, and was concerned that he may have swallowed a large amount of seawater. He denied having chest pain or shortness of breath. He was shivering vigorously with occasional coughing. There was no significant past medical history and the patient was not taking any medications. Initial vital signs revealed a core body temperature of 30.30C (86.50F), his pulse was irregularly irregular ranging from 120 to 170 beats per minute, respirations were 28 breaths per minute, and blood pressure was 153/100 mm Hg. Oxygen saturation was 95% on room air.

2. The degree of hypothermia in this patient would be classified as:

a. Mud

b. Moderate

c. Severe

The severity of hypothermia is determined based on the patient's core body temperature.4,5 The degree of hypothermia guides the treatment of the patient (Table I). Mild hypothermia is a core temperature from