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From: ron@brl-tgr.ARPA (Ron Natalie )
Newsgroups: net.med
Subject: Re: blood pressure
Message-ID: <5173@brl-tgr.ARPA>
Date: Wed, 10-Oct-84 15:27:26 EDT
Article-I.D.: brl-tgr.5173
Posted: Wed Oct 10 15:27:26 1984
Date-Received: Fri, 12-Oct-84 05:11:04 EDT
References: <3778@tektronix.UUCP> <127@logico.UUCP>
Organization: Ballistics Research Lab
Lines: 35

Springier?  It's not the elasticity of the artery that determines
how much pressure it takes to cut off the circulation, it is the
pressure of the flow that makes the difference.  Systole (indicated
by the higher numbers) is an index of how hard the heart is making
it's stroke, diastole is the rest (actually, filling) period.  The
primary reason blood pressure goes up is becuase for some reason
the heart is pumping harder to get the same volume of blood through.
As your demand for blood contents (oxygen, notably) goes up, the heart
has to pump more blood.  A more dramatic change happens to the person
with the healty heart (not a more serious, just more dramatic) goes
into shock.  His heart will raise the pressure to keep the volume up
until a point is reached and a collapse occurs, while less healthy
people will just go into a gradual loosing battle.

The rule of thumb is "for an adult male up to age 40, at rest, add
his age to 100 for the systolic blood pressure, for females add to
90).  Serious low blood pressure indicates shock (loss of volume),
high blood pressure indicates the heart is working harder than usual
to pump the blood.
High blood pressure usually is considered bad because it indicates
other problems like arteriosclerosis or it may cause a higher
risk of hemmorage due to increased pressure.  I don't think anyone
claims that blood pressure alone is the problem, but having high
blood pressure is a sign for a need for further investigation.

Actually, all my experience with blood pressure is emergency
medicine based.  We use blood pressure as a baseline and watch
for changes.  We don't condider problems unless the blood pressure
is really high (>180) or really low (<80) or it changes drastically.
Other indicators like the systolic and diastolic numbers growing closer
together idicate a decrease in heart efficiency sometimes due to blood
in the pericardium.

-Ron
w