Page 638 - ACCCN's Critical Care Nursing

Emergency Presentations 615

more invasive and carries associated risks, and so is impaired neurological function. 198 Heat stroke is a pro-
reserved for profoundly hypothermic patients. 191 found disturbance of the body’s heat-regulating ability,
and is often referred to as ‘sunstroke’, although it relates
External warming is indicated only if the core tempera-
ture is above 32°C, as this may cause vasodilation and to the body’s inability to dissipate heat, loss of sweat
hypovolaemic shock. Shunting of cold peripheral blood function and severe dehydration, rather than actual sun
198,199
to the core may also lead to further chilling of the exposure.
myocardium and ventricular fibrillation. 191,192 External
warming using warm blankets, forced warm air blankets, Management
and heat packs in contact with the patient’s body should Initial management of the hyperthermic patient focuses
raise body temperature by approximately 2.5°C per on airway, breathing and circulation, 198,199 with correction
hour. 191,192 Inhalation rewarming with oxygen warmed to of urgent physiological states such as hypoxia, severe
42–46°C is also effective, as around 10% of metabolic potassium imbalances and acidosis. A heat-stressed
heat is lost through the respiratory tract. 195 patient can have large fluid losses and require prompt
fluid resuscitation, preferably isotonic sodium chloride
HYPERTHERMIA AND HEAT ILLNESS solution. 198,199 Total water deficit should be corrected

DESCRIPTION AND INCIDENCE slowly; half of the deficit is administered in the first 3–6
199
hours, with the remainder over the next 6–9 hours.
Heat-related illness is common in Australia, although
there are only limited deaths. 198,199 Alterations in thermo- Rapid cooling is the second priority: lowering core tem-
regulatory function cause varying degrees of heat illness, perature to <38.9°C within 30 minutes improves survival
198
categorised as three types: heat cramps, heat exhaustion and minimises end-organ damage. The ideal goal is
199
and heat stroke. 198,199 Excess exposure to heat substan- to reduce the core temperature by 0.2°C/min. Non-
tially increases fluid and electrolyte losses from the invasive external methods of cooling include removal of
body. 198,199 The loss of both fluids and electrolytes in clothing and covering the patient with a wet, tepid sheet.
addition to impaired organ function lead to the compli- Ice packs can be placed next to the patient’s axillae, neck
cations of heat illnesses. Factors contributing to heat and groin. Invasive cooling measures such as iced gastric
illness include elevated ambient temperature, increased lavage, iced peritoneal lavage and cardiopulmonary
heat production due to exercise, infection, and drugs such bypass are reserved for the patient who fails to respond
199
as amphetamines, phenothiazines or other stimulants. 198 to conventional cooling methods. Core body tempera-
Impaired heat dissipation is caused by exposure to ture should be monitored using a continuous rectal or
high ambient temperatures with high humidity, a failure tympanic probe. No randomised clinical trials have com-
199
of acclimatisation, excessively heavy clothing, inade- pared the effectiveness of different cooling methods.
quate fluid intake leading to dehydration and sweat
dysfunction. 198 SUMMARY
CLINICAL MANIFESTATIONS This chapter has provided an overview of important ED
systems and processes, outlining the practice of initial
Environmental heat illness is more likely to develop assessment and prioritisation of patients presenting to
when the ambient temperature exceeds 32–35°C and the the ED through the unique nursing process of triage. The
humidity is greater than 70%. 198,199 Assessment of the role of the emergency nurse, including aspects of extended
patient’s physical state and vital signs including GCS practice and the role of the emergency nurse practitioner,
score provides evidence of hypovolaemia and shock.
were described. The initial ED management of common
Heat exhaustion is a more severe form of heat illness and emergency presentations were outlined reflecting current
is associated with severe water or salt depletion due to practice and based on the latest available evidence.
excessive sweating and a temperature below 40°C. Com-
bined water and salt loss causes muscle cramps, nausea The emergency environment is dynamic, and it was
and vomiting, headache, dizziness, weakness, fainting, beyond the scope of this chapter to describe the full
thirst, tachycardia, hypotension, profuse sweating, but extent of emergency nursing practice and the clinical
with normal neurological function. Haemoconcentration entities that they manage. It is therefore important for
is noted if body water has been sufficiently depleted, a critical care nurse to be familiar with the content pro-
while serum sodium can be either high or low depending vided in the other chapters in this text, as well as other
on the relative amounts of salt and water lost. 198 resources. As noted at the beginning of this chapter,
other common presentations to the ED, such as trauma
Heat stroke is the most severe and serious form of and cardiorespiratory arrest, are described in Chapters
heat-related illness, with temperatures above 41°C and 23 and 24.