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Vital Signs

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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 140160 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 130150 beats per minute. A toddler's heart will beat about 100120 times per minute, an older child's heartbeat is around 60100 beats per minute, adolescents around 80100 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 1220 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.

    
       

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