Loss of consciousness

This manikin does not respond to stimuli, and thus must be unconscious, in a coma, or perhaps dead.

Definition

A loss of being conscious, the state of being aware and mentally able to respond to stimuli.

So if you are asleep and someone pokes you, you wake up, responding to stimuli and thus not being unconscious. If you are in a coma, you won't wake up, and are thus unconscious.

Epidemiology

An estimated 15% of emergency admissions are from conciousness issues.

Pathophysiology

The commonest cause is due to a reduction in oxygen flow to the brain. Most commonly this occurs from fainting or "syncope", where a temporary reduction in flow to the brain. Can also be caused from breathing air that's low in oxygen.

Symptoms, Sign and Differential

There is a huge range of causes. The most common cause is syncope, which is a harmless faint.

The best way to explain the others is to split them up by symptoms, and show common conditions:

Vital signs

• High blood pressure: Brain haemorrhage, raised ICP, renal or endocrine problems.
• Low blood pressure: Blood loss, diabetic coma, alcohol or drug abuse
• Hyperthermia: Infection, Heat stroke, withdrawal.
• Hypothermia: Shock, alcohol or drug abuse
• Bradycardia: Heart block, raised ICP
• Tachycardia: Arrhythmia, atrial fibrillation causing a stroke.

Other stuff

• Neck stiffness - Meningitis or encephalitis, trauma or brain haemorrhage.
• Tongue bitten - Epilepsy