g. Cheyne-Stokes is the term for cycles of breathing characterized by deep, rapid
breaths for about 30 seconds, followed by absence of respirations for 10 to 30 seconds.
Cheyne-Stokes respirations constitute a serious symptom and usually precedes death in
cerebral hemorrhage, uremia, or heart disease.
4-18. BLOOD PRESSURE
Two things determine the blood pressure: the rate and force of the heartbeat and
the ease with which the blood flows into the small branches of the arteries. When the
heart rate or force is increased by exertion or illness, blood pressure increases. If the
volume of blood within the circulatory system is reduced (as in hemorrhage), and other
factors remain the same, blood pressure decreases.
a. Blood pressure is the pressure exerted by the blood on the walls of the blood
vessels within the systemic arterial system. Normal systolic pressure for a young adult is
100 to 120 mmHg (millimeters of mercury); diastolic pressure is about 80. Blood pressure
increases gradually with age. Normal systolic pressure for a person 60 years of age is 130
to 140. Hypertension is blood pressure above normal limits (above 140/90); it is a sign of
a circulatory problem. Hypotension is blood pressure below normal limits (below 90/60)
and may indicate shock. See table 4-3.
100 to 140 mmHg
60 to 90 mmHG
Table 4-3. Normal range of adult blood pressure.
b. Systolic blood pressure is greatest. It is the pressure against the wall of the
blood vessels following ventricular contraction. Using the auscultatory (listening) method,
the systolic blood pressure is recorded at the highest point at which two consecutive beats
are heard (Korotkoff sounds).
c. Diastolic blood pressure is lowest. It is the pressure against the blood vessels
when the heart is relaxed before it begins to contract again.
d. The mean arterial pressure (MAP) denotes the average pressure within the
arteries. An electronic vital signs monitor can determine and display an accurate average
pressure or MAP.
e. Shock or other difficulty is usually indicated by a systolic reading of 80 or less.
A diastolic reading over 100 is usually considered dangerously high.