Vital signs

Vital signs are measures of various physiological statistics, often taken by health professionals, in order to assess the most basic body functions. Vital signs are an essential part of a case presentation. The act of taking vital signs normally entails recording body temperature, pulse rate (or heart rate), blood pressure, and respiratory rate, but may also include other measurements. Vital signs often vary by age.

Primary four
There are four vital signs which are standard in most medical settings:
 * 1) Body temperature
 * 2) Pulse rate (or heart rate)
 * 3) Blood pressure
 * 4) Respiratory rate

The equipment needed is a thermometer, a sphygmomanometer, and a watch.

Though a pulse can often be taken by hand, a stethoscope may be required for a patient with a very weak pulse.

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 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.

Additional signs
While various additional signs have been proposed, none have been officially universally adopted due to the expense in obtaining equipment required to diagnose and the difficulty in training entry-level professionals.

Fifth sign
The phrase "fifth vital sign" usually refers to pain, as perceived by the patient on a pain scale of 0–10. For example, the Veterans Administration made this their policy in 1999. However, some doctors have noted that pain is actually a subjective symptom, not an objective sign, and therefore object to this classification.

Other sources include oxygen saturation as their fifth sign.

Some sources consider pupil size, equality, and reactivity to light to be a vital sign as well.

Many EMS agencies in the United States use pulse oximetry and blood glucose level as vital signs in addition to pulse, respiratory rate, and blood pressure.

Sixth sign
There is no standard "sixth vital sign", and the use is much more informal and discipline-dependent than with the above, but some proposals (excluding the fifth sign candidates above) include:


 * Urinary continence
 * End-tidal CO2
 * Emotional distress
 * Spirometry
 * Glucose
 * Functional status
 * Shortness of breath
 * Gait speed

Variations by age
Children and infants have respiratory and heart rates that are faster than those of adults as shown in the following table:

Monitoring
Monitoring of vital parameters most commonly include at least blood pressure and heart rate, and preferably also pulse oximetry and respiratory rate. Multimodal monitors that simultaneously measure and display the relevant vital parameters are commonly integrated into the bedside monitors in critical care units, and the anesthetic machines in operating rooms. These allow for continuous monitoring of a patient, with medical staff being continuously informed of the changes in general condition of a patient.