Sports Medicine: Just the Facts

CHAPTER 39 • ENVIRONMENTAL INJURIES 233

a rectal temperature obtained with a thermometer

scaled for hypothermia is required. Oral and ear tem-

peratures are grossly inaccurate. A core temperature

above 35°C can rapidly exclude hypothermia.

• Common laboratory findings include a falsely ele-
  vated hematocrit caused by dehydration, a low leuko-
  cyte count caused by sequestration, hyperamylasemia
  resulting from pancreatic injury, an aberrant coagula-
  tion profile, hypokalemia and hypoglycemia caused
  by glycogen depletion. Below 30°C insulin is ren-
  dered inactive and a paradoxic hyperglycemia can
  ensue (Danzl, 2001).

TREATMENT

• Field treatment should focus on gentle handling of the
  victim so as to not cause cardiac dysrhythmias. Wet
  clothing should be removed and dry clothing or a blan-
  ket applied. Massage of cold-injured limbs should be
  avoided; it can damage fragile, frozen parts and trigger
  dysrhythmias. Traumatic injuries to the spine or limbs
  should be stabilized. An airway should be maintained
  and cardiac monitoring begun if available. If the skin is
  frozen, needle electrodes should be used or fashioned
  by passing a 20-gauge needle through an electrode pad
  into the frozen skin. If the patient is alert—warm, non-
  caffeinated beverages can be provided.


• Fluid resuscitation with IV D5NS should be started.
  Lactated Ringers should be avoided because of prob-
  lems with the metabolism of lactate by a cold-
  injured liver (level of evidence B/C, nonrandomized
  clinical trials and expert opinion). (Danzl, 2001;
  ECC Guidelines of the American Heart Association,
  2000).


• Emergency room treatment should focus on rewarm-
  ing of the patient. Defibrillation is limited to three
  countershocks until the core temperature is raised
  above 30°C (86°F) (level of evidence B, nonrandom-
  ized clinical trials). (ECC Guidelines of the American
  Heart Association, 2000).


• Passive external rewarming(PER) by covering the
  victim with a blanket or wrap is ideal in an alert patient
  whose core temperature is greater than 32°C (90°F).


• Below 90°F, rewarming should proceed with active
  core rewarming(ACR) (level of evidence B, system-
  atic reviews, uncontrolled trials) (Lazar, 1997; Danzl
  et al, 1987; Danzl and Pozos, 1994a). This can be
  accomplished with IV D5NS warmed to 40–42°C
  (104–108°F), or the inhalation of humidified oxygen
  warmed to 104–108°F. More invasive techniques
  include peritoneal lavage with dialysate warmed to
  104–108°F, thoracic lavage with normal saline at
  104–108°F or warming of the gastrointestinal tract
  with gastric/colonic lavage.
  
  
  • Active external rewarming(AER), (fires, hot water
    bottles, and heating pads) should be employed only
    when ACR has already begun to avoid the life-threat-
    ening risk of core temperature afterdrop. This devas-
    tating process occurs when sudden exposure of
    vasoconstricted cool extremities to AER, causes
    peripheral vasodilatation, a drop in central blood pres-
    sure, and a sudden influx of cool blood from the
    periphery to the core that can trigger dysrhythmias and
    shock (Danzl, 2001). Table 39-1 provides an overview
    of hypothermia severity and ideal treatment modalities
    (Danzl, 2001).
  
  
  
  

PREVENTION

• Good conditioning, proper nutrition, experienced
  leadership in backcountry environments, normal
  hydration, avoidance of ethanol or tobacco, habitua-
  tion to the cold environment (both physiologic and
  behavioral), and the use of proper clothing help pre-
  vent hypothermia.


• Clothing choice centers on the 3 Ls: layered, loose,
  and lightweight. A waterproof outer layer is key. If
  exercise is occurring in a temperature of <0°F three-
  layered hand and footwear are optimal for the preven-
  tion of frostbite.

FROSTBITE

DEFINITIONS

• Frostbite is freezing of tissues leading to damage.
  Frostnip is the formation of superficial ice crystals and
  causes no tissue damage.Chilblains is an autoimmune
  lymphocytic vasculitis, common in women, that leads
  to localized nodules or ulcers on the extremities 12 h
  after cold exposure.

TABLE 39-1 Hypothermia Severity and Treatment

TEMPERATURE CLINICAL FEATURES TREATMENT

35 °C/95°F Maximum shivering Passive external

rewarming

33 °C/91°F Ataxia, apathy, tachypnea Passive external

warming

32 °C/90°F Stupor, shivering stops Active core

rewarming

(±active external

rewarming)

28 °C/82°F Decreased v-fibrillation Active core

threshold, hypoventilation rewarming

14 °C/57°FLowest adult accidental Active core

hypothermia survival rewarming

9 °C/48°FLowest therapeutic survival Active core

rewarming