There are four vital signs which are standard in most medical
settings:
Body temperature
Pulse rate (or heart rate)
Blood pressure
Respiratory rate
Temperature
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 body 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.
Temperature is commonly considered to be a vital sign most
notably in a hospital setting. EMTs (Emergency Medical Technicians), in
particular, are taught to measure the vital signs of: respiration, pulse, skin,
pupils, and blood pressure as "the 5 vital signs" in a non-hospital setting.
Blood pressure
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).
Pulse
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 60�100 beats per minute, adolescents around 80�100 beats per minute, and
adults' pulse rate is anywhere between 50 and 80 beats per minute.
Respiratory rate
Varies with age, but the normal reference range for an adult is
12�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 in
circulation.
