Vital signs indicate the status of the cardiovascular system and the CNS and include pulse, respiratory rate and quality, blood pressure, and temperature. Abnormal vital signs indicate a serious injury or illness. When warranted, the vital signs should be assessed to establish a baseline of information. This is done by a clinician or any qualified individual with a first aid training. The main vital signs are pulse, respiration, blood pressure and temperature.
First is the pulse. Factors such as age, gender, aerobic physical condition, degree of physical exertion, medications or chemical substances being taken, blood loss, and stress can influence pulse rate and volume. Pulse usually is taken at the carotid artery, because a pulse at that site is not normally obstructed by clothing, equipment, or strappings. Normal adult resting rates range from 60 to 100 beats a minute; for children, the normal resting range is from 120 to 140 beats per minute. Aerobically conditioned athletes may have a pulse rate as low as 40 beats per minute. Pulse rate is assessed by counting the carotid pulse rate for a 30-second period and then doubling it. An assessment of pulse volume, which reflects the sensation of the contraction (e.g., strong/weak), also is important.
Next is the respiration. Breathing rate also varies with gender and age. It averages from 10 to 25 breaths per minute in an adult and from 20 to 25 breaths per minute in a child. Breathing rate is assessed by counting the number of respirations in a 30-second period and then doubling it. The character of the respiration (e.g., rapid, shallow, deep, gasping, or labored) should be noted as well.
Third is the blood pressure. Blood pressure is the pressure or tension of the blood within the systemic arteries, generally considered to be the aorta. As one of the most important vital signs, blood pressure reflects the effectiveness of the circulatory system. Changes in blood pressure are very significant. Systolic blood pressure is measured when the left ventricle contracts and expels blood into the aorta. It is approximately 120 mm Hg for a healthy adult and 125 to 140 mm Hg for healthy children aged 10 to 18 years. Diastolic blood pressure is the residual pressure in the aorta between heartbeats and averages 70 to 80 mm Hg in healthy adults and 80 to 90 mm Hg in healthy children aged 10 to 18 years. Blood pressure may be affected by gender, weight, race, lifestyle, and diet. Blood pressure is measured in the brachial artery with a sphygmomanometer and stethoscope.
Lastly, the temperature. Core temperature can be measured by a thermometer placed under the tongue, in the ear or armpit, or in case of unconsciousness, in the rectum. Average oral temperature usually is quoted at 37°C (98.6°F), but this can fluctuate considerably. During the early morning hours, it may fall as low as 35.8°C (96.4°F), and during the later afternoon or evening hours, it may rise as high as 37.3°C (99.1°F). Rectal temperatures are higher than oral temperatures by an average of 0.4 to 0.5°C (0.7–0.9°F). Although this too can be quite variable, it is considered to be a more accurate measurement of core temperature. In contrast, axillary temperatures are lower than oral temperatures by approximately 1°F.
Reference:
Magee, DJ. Orthopedic Physical Assessment. Philadelphia: WB Saunders, Elsevier Science, 2002.
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