Environmental Emergencies 207HEAT, COLD AND DROWNING3 Cardiac arrest in a hypothermic patient
(i) Severe hypothermia (core temperature <30°C)
(a) attempt defibrillation once for VF, delivering 150–200 J
biphasic or 360 J monophasic
(b) standard resuscitation drugs are usually ineffective as the
efficacy of adrenaline (epinephrine) and amiodarone are
reduced, with an increased circulation time
(c) provide aggressive active internal re-warming with warmed
40°C pleural, gastric or peritoneal lavage, aiming for a core
temperature rise to at least 33°C
(d) extracorporeal blood re-warming is ideal, when available.
(ii) Moderate hypothermia (core temperature 30–32°C)
(a) attempt defibrillation with one direct current (DC) shock
(b) administer standard resuscitation medications, but double
the time between doses.
(iii) Apply usual resuscitation protocols with core temperatures of
≥33°C.
(iv) Continue resuscitation attempts in hypothermic cardiac arrest
until the core temperature rises to at least 33°C, or until a senior
doctor advises to the contrary
(a) this may involve a prolonged period of resuscitation and
aggressive measures as outlined.
Drowning
DIAGNOSIS
1 Drowning is a common cause of accidental death in Australasia and Europe.
It is defined as any process that results in primary respiratory impairment
following immersion (face and upper airway), or submersion (whole body) in
a liquid medium.
2 The duration of hypoxia is the most important factor that determines
outcome and a full neurological recovery. Victims with spontaneous circula-
tion and breathing on arrival at hospital usually have a good outcome.
3 The presence of lung crackles indicates likely inhalation of water, with the
risk of hypoxaemia. The initial difference between sea-water (hypertonic)
and fresh-water (hypotonic) drowning is of little clinical significance.
However, contaminated water such as sewage will require antibiotic
prophylaxis.
(i) About 15% of drowned victims experience ‘dry drowning’,
assumed due to laryngospasm, where little or no fluid is found in
the lungs.
4 Consider other more relevant factors:
(i) Preceding injury, especially to the cervical spine in a diving
accident.