DEFINITION:  Syncope is defined as a transient loss of consciousness.

• It is usually due to a deficit of nutrients to the brain (decreased blood flow, typically by a fall in blood pressure, lasting 8-10 seconds.)
• Recovery is usually complete and rapid, rarely lasting >1-2 minutes. (Longer suggests it is something much more than just syncope, such as a head injury that prolongs loss of consciousness.

EPIDEMIOLOGY: The incidence of syncope increases with age, with a sharp rise > 70 years of age.

This increased risk is due to age- and disease-related abnormalities that impair the ability to respond to physiologic stresses that would ordinarily not cause syncope in younger persons.

Causes

Syncope, in general, is divided into four major categories:

1. Reflex syncope (neurological).
2. Orthostatic syncope.
3. Cardiac arrhythmias.
4. Structural cardiopulmonary disease.

In the elderly, there are many causes for syncope, but usually they are cardiac or neurological in nature:

• Vasovagal syncope (the "common" faint, after sudden sight, sound, smell, or pain). It is a reflex syncope in which neural reflexes modify heart rate and blood pressure inappropriately.
• Carotid sinus hypersensitivity (more common in the elderly, due to head-turning, tumors, shaving, or tight collars).
• Arrhythmia (14%): AV block, cardiac pauses, ventricular tachyarrhythmias.
• Orthostatic hypotension (8-10%, associated with a decrease in systolic blood pressure of at least 20 mmHg or in diastolic blood pressure of at least 10 mmHg, upon assuming upright posture).

Aging is associated with an increased prevalence of orthostatic hypotension, probably due to changes in the vestibulosympathetic reflex. Other common causes are

• decreased intravascular volume,
• antidepressants, and
• antihypertensives (especially vasodilators.

• Cerebrovascular disease (TIA, stroke, etc.).
• Glucose variations (post-prandial).

However, the cause is unknown in roughly a third of cases.

Complications of Syncope

Syncope is usually self-limited, and therefore recovery is complete. However, loss of consciousness also causes loss of postural tone and collapse, which may cause injury from falls or worse, accidents involving motor vehicles or heavy machinery.

In the Field

In the field, your most likely interaction with an elderly patient who experiences syncope will be dealing with either the cause of syncope (cardiac or neurological conditions) or the results of syncope (trauma from falls, accidents, etc.).

Besides the immediate needs of addressing any serious injuries, a quick assessment of level of consciousness and the rate and rhythm of the pulse are imperative to identify common neurological and cardiac causes.

As such, support for ABC (airway, breathing, circulation) is important, along with O2 when indicated and IV access en route. Your most important obligation for a transient loss of consciousness it to make sure it is transient!