Hello. This is vascular medicine: the advanced
components. And this section we'll discuss
hypotension—that is, decreased blood pressure—and
So let's start with the definition, as we've
done in each of the other cases. Hypotension,
or decreased blood pressure, is a blood pressure
less than 100 mmHg systolic blood pressure,
where the normal is generally, in the population,
about 120/80. There are common symptoms associated
with decreased blood pressure: fatigue; dizziness
or lightheadedness; and occasionally, even
fainting. Patients may have a fast
heart rate; they may have a slow heart rate.
But their blood pressure is low. The skin
can be warm and not very sweaty
in some patients, where they're markedly vasodilated
in the skin. Or they may have cool, sweaty
skin when the skin is very vasoconstricted.
And hypotension is very commonly related to
dehydration or blood loss.
Shock is more severe than hypotension. Shock
is not only low blood pressure, but it is
an associated decrease in blood flow to critical
organs. For example, it's a life-threatening
condition. It's not only low blood pressure,
but the brain and the heart and the kidneys
are not getting enough blood flow, and they
start to malfunction. This shock usually occurs
in the setting of a very serious medical illness—for
example, a large heart attack (large myocardial
infarction), or an overwhelming bacterial
infection where the bacteria are in the bloodstream,
or a serious hemorrhage.
The diagnosis is usually pretty straightforward.
It consists of noticing that the blood pressure
is low with a blood pressure cuff. And the
patients show a number of signs when they
have very low blood pressure. They're often
confused. In many patients, they will have
cool and sweaty skin and be pale. They have
low urine output, because the kidney's not
getting enough blood flow. And they often
have a rapid heartbeat. However, there are
exceptions. There are periods... states where
the shock state is associated with warm, dry
skin and with a slow heart rate, although
there is almost always low urine output and
The causes are many, but as I said in the
first sentence in this unit, it is always—almost
always —a very serious medical condition.
• A myocardial infarct or a heart attack
• Bacteria in the bloodstream
• A hemorrhage from some injury
• Severe dehydration: We see this very commonly
where I work, in Tucson, Arizona, in the desert.
In the summertime, when the temperatures are
well... can be well over 40°C, and the humidity
can be 5%, dehydration is very common.
• And finally, patients with severe heart
failure, where the heart is functioning very
Each of these can result in the shock state.
A number of factors can lead to this, as I've