Heat Illness
Heat illness is classified as either minor or major. Whilst two distinct entities, minor can rapidly progress to major and the two should be considered a spectrum of illness. This is even more pertinent in the pre hospital environment when accurate core temperature readings will often not be available or appropriate.
Minor Heat Illness
Minor heat illness is an elevation in the core temperature above normal, but to less than 40°C. Patients with this condition will often have often mild symptoms and it is important that the practitioner maintains a high index of suspicion.
Sign and symptoms
Patients with heat illness may develop muscule cramps. These can be severe in nature, and often affect large muscle groups such as quadriceps, hamstrings or abdominal wall.
Individuals with heat illness may also become oedematous although this feature is not always present.
As the condition progresses, the patient is likely to be hyperventilating in an attempt to maximise heat loss and may develop carpopedal spasm.
Vasodilation is another compensatory mechanism to maximise heat loss, , this can result in peripheral pooling of blood, with relative hypotension (distributive shock) pressure, causing the patient to feel dizzy and lead to syncope.
If left unrecognised or inadequately treated, these individuals will become exhausted and may progress to major heat illness.
Minor heat illness treatment
It is important to intervene before the patient progresses to a more serious major heat illness.
The player should be removed to a cool environment and should not be allowed to continue their sporting activity.
It may be necessary to take measures to actively cool the patient, including fanning, or spraying with lukewarm water. Spraying with ice-cold water should be avoided as this may cause peripheral vasoconstriction and a paradoxical rise in the core temperature.
Cool IV fluids may be useful in some cases, particularly when cramps are a problem.
Major Heat Illness
Major heat illness is a serious medical emergency with a mortality rate approaching 10%. It is vital that this condition is recognised early and managed appropriately. A patient with major heat illness will have a core temperature of 40°C or higher. There will be neurological features, as well as multisystem problems.
Be aware, that in the prehospital environment it can be difficult to obtain an accurate core temperature. A gradient may exist between core and peripheral temperatures, and peripheral temperature should not be relied upon for diagnosis. If a patient is pyrexial, and has neurological signs as outlined below, then it is safer to assume major heat illness and treat for this.
As the condition progresses, catastrophic cellular dysfunction, swelling, collapse and ultimately death may occur.
Signs and symptoms
In the early stages, patients will be confused and irritable, but this may rapidly progress to collapse with a reduced conscious level, seizures and later decerebrate posturing.
The exact neurological presentation may vary between individuals and any neurological abnormality must be taken seriously.
The patient will also be tachycardic and tachypnoeic. Hypotension will likely also be present as the condition deteriorates.
If left untreated, cardiac arrest is likely.
It is outside the scope of this text to discuss the effects on the patient’s renal, hepatic or haematological systems, or for a more detailed discussion on the effects on the cardiovascular and respiratory systems.
Treatment of Major heat illness
Early recognition is vital, and as soon as the diagnosis is suspected, the player should be actively cooled, while arrangements are being made to transfer them to an appropriate emergency department as soon as possible.
They must be moved to a cool environment. An assessment of the patient according to the usual ABCDE system should take place, with any necessary interventions made. High flow oxygen should be administered via a non-rebreathe mask. Intravenous access should be established and intravenous fluids administered.
The patient should be sprayed with lukewarm water and fanned. Ice packs can be applied to pulse points in the armpits, groin and neck.
Rapid transfer to an appropriate emergency department with an appropriate pre-alert call is a vital step in the management of this patient. The patient is likely to require management on an intensive care unit.
If a patient has seizures, these should be managed cautiously with buccal, intravenous or rectal benzodiazepines. The practitioner must be aware of the potential for respiratory depression and be ready to manage this .
Antipyretics (paracetamol and non-steroidal anti-inflammatory drugs) are not effective in reducing the temperature due to heat stroke.