There are four vital signs which are standard in most medical
Pulse rate (or heart rate)
The equipment needed is a thermometer, a sphygmomanometer, and a
Though a pulse can often be taken by hand, a stethoscope may be
required for a patient with a very weak pulse.
Temperature recording gives an indication of core body
temperature which is normally tightly controlled (thermoregulation)
as it affects the rate of chemical reactions.
Temperature can be recorded in order to establish a baseline for
the individual's normal temperature for the site and measuring
conditions. The main reason for checking body temperature is to
solicit any signs of systemic infection or inflammation in the
presence of a fever (temp > 38.5°C or sustained temp > 38°C), or
elevated significantly above the individual's normal temperature.
Other causes of elevated temperature include hyperthermia.
Temperature depression (hypothermia) also needs to be evaluated.
It is also noteworthy to review the trend of the patient's
temperature. A patient with a fever of 38°C does not necessarily
indicate an ominous sign if his previous temperature has been
higher. Body temperature is maintained through a balance of the heat
produced by the body and the heat lost from the body.
The blood pressure is recorded as two readings; a high systolic
pressure, which is the maximal contraction of the heart, and the
lower diastolic or resting pressure. A normal blood pressure would
be 120 being the systolic over 80, the diastolic. Usually the blood
pressure is read from the left arm unless there is some damage to
the arm. The difference between the systolic and diastolic pressure
is called the pulse pressure. The measurement of these pressures is
now usually done with an aneroid or electronic sphygmomanometer. The
classic measurement device is a mercury sphygmomanometer, using a
column of mercury measured off in millimeters. In the United States
and UK, the common form is millimeters of mercury, whilst elsewhere
SI units of pressure are used. There is no natural 'normal' value
for blood pressure, but rather a range of values that on increasing
are associated with increased risks. The guideline acceptable
reading also takes into account other co-factors for disease.
Therefore, elevated blood pressure (hypertension) is variously
defined when the systolic number is persistently over 140–160 mmHg.
Low blood pressure is hypotension. Blood pressures are also taken at
other portions of the extremities. These pressures is called
segmental blood pressures and are used to evaluate blockage or
arterial occlusion in a limb (see Ankle brachial pressure index).
The pulse is the physical expansion of the artery. Its rate is
usually measured either at the wrist or the ankle and is recorded as
beats per minute. The pulse commonly taken is from the radial artery
at the wrist. Sometimes the pulse cannot be taken at the wrist and
is taken at the elbow (brachial artery), at the neck against the
carotid artery (carotid pulse), behind the knee (popliteal artery),
or in the foot dorsalis pedis or posterior tibial arteries. The
pulse rate can also be measured by listening directly to the
heartbeat using a stethoscope. The pulse varies with age. A newborn
or infant can have a heart rate of about 130-150 beats per minute. A
toddler's heart will beat about 100-120 times per minute, an older
child's heartbeat is around 90-110 beats per minute, adolescents
around 80-100 beats per minute, and adults pulse rate is anywhere
between 50 and 80 beats per minute.
Varies with age, but the normal reference range for an adult is
10–20 breaths/minute. The value of respiratory rate
as an indicator of potential respiratory dysfunction has been
investigated but findings suggest it is of limited value.
Respiratory rate is clear indicator of acidotic states, as the main
function of respiration is removal of CO2 leaving bicarbonate base