What are vital signs?

Vital signs are measurements of the body's most basic functions. The 4 main vital signs routinely checked by healthcare providers include:

• Body temperature

• Pulse rate

• Breathing rate (respiration)

• Blood pressure

Vital signs help detect or monitor medical problems. They can be measured in a medical setting, at home, at the site of a medical emergency, or elsewhere.

What is body temperature?

The normal body temperature of a person varies depending on gender, recent activity, food and fluid consumption, time of day, and, in women, the stage of the menstrual cycle. Normal body temperature can range from 97.8° F (36.5°C) to 99°F (37.2°C) for a healthy adult. A person's body temperature can be taken in any of the following ways:

• Orally. Temperature can be taken by mouth using a digital thermometer that uses an electronic probe to measure body temperature.

• Rectally. Temperatures taken rectally tend to be 0.5°F to 0.7°F higher than when taken by mouth. This is more common in babies because their body doesn't regulate temperature the way an older child or adult's body does.

• Armpit (axillary). Temperatures can be taken under the arm using a digital thermometer. Temperatures taken by this route tend to be 0.3°F to 0.4°F lower than those temperatures taken by mouth.

• By ear. A special thermometer can quickly measure the temperature of the eardrum, which reflects the body's core temperature (the temperature of the internal organs).

• By skin. A special thermometer can quickly measure the temperature of the skin on the forehead. Some thermometers don't require contact with the skin to get a temperature reading.

• Internally. This method is common in people who are critically ill in an intensive care unit (ICU). The temperature can be measured by probes that are placed in the esophagus, heart, or bladder.

Body temperature may be abnormal due to fever (high temperature) or hypothermia (low temperature). A fever is indicated when body temperature rises about 1 degree or more over the normal temperature of 98.6°F, according to the American Academy of Family Physicians. Hypothermia is defined as a drop in body temperature below 95°F.

Glass thermometers containing mercury

Exposure to mercury can be toxic and poses a threat to a person's health, as well as to the environment. Don't use glass thermometers with mercury, as they can break. If you have a mercury thermometer, dispose of it correctly in accordance with local, state, and federal laws. Contact your local health department, waste disposal authority, or fire department for information on how to correctly dispose of mercury thermometers.

What is the pulse rate?

The pulse rate is a measurement of the heart rate. This is the number of times the heart beats per minute. As the heart pushes blood through the arteries, the arteries expand and contract with the flow of the blood. Taking a pulse not only measures the heart rate, but also can indicate the following:

• Heart rhythm

• Strength of the pulse

The normal pulse for healthy adults ranges from 60 to 100 beats per minute. The pulse rate may fluctuate and increase with exercise, illness, injury, and emotions. Females ages 12 and older, in general, tend to have faster heart rates than do males. Athletes, such as runners, who do a lot of cardiovascular conditioning, may have heart rates near 40 beats per minute with no problems.

How to check your pulse

As the heart forces blood through the arteries, you feel the beats by firmly pressing on the arteries, which are located close to the surface of the skin at certain points of the body. The pulse can be found on the side of the neck, on the inside of the elbow, at the wrist, or in the groin. For most people, it's easiest to take the pulse at the wrist. If you use the lower neck, be sure not to press too hard. Never press on the pulses on both sides of the lower neck at the same time. This can block blood flow to the brain.

When taking your pulse:

• Using the first and second fingertips, press firmly but gently on the arteries until you feel a pulse.

• Start counting the pulse when the clock's second hand is on the 12.

• Count your pulse for 60 seconds (or for 30 seconds and then multiply by 2 to calculate beats per minute).

• When counting, don't watch the clock continuously, but concentrate on the beats of the pulse.

• If unsure about your results, ask another person to count for you.

If your healthcare provider has asked you to check your own pulse and you are having trouble finding it, consult your provider or nurse for advice. Many types of monitoring devices can help check your pulse. These include fitness tracker devices to help track your pulse rate.

What is the respiration rate?

The respiration rate is the number of breaths you take each minute. The rate is usually measured when you are at rest. It simply involves counting the number of breaths for 1 minute by counting how many times your chest rises. Respiration rates may increase with exercise, fever, illness, and with other medical conditions. When checking respiration, it's important to also note whether you have any trouble breathing.

Normal respiration rates for an adult person at rest range from 12 to 20 breaths per minute.

What is blood pressure?

Blood pressure is the force of the blood pushing against the artery walls during contraction and relaxation of the heart. Each time the heart beats, it pumps blood into the arteries. It results in the highest blood pressure as the heart contracts. When the heart relaxes, the blood pressure falls.

Two numbers are recorded when measuring blood pressure. The higher number is called systolic pressure. It refers to the pressure inside the artery when the heart contracts and pumps blood through the body. The lower number is called diastolic pressure. It refers to the pressure inside the artery when the heart is at rest and is filling with blood. Both pressures are recorded as "mm Hg" (millimeters of mercury).  

High blood pressure directly increases the risk of heart attack, heart failure, and stroke. With high blood pressure, the arteries may have an increased resistance against the flow of blood. This causes the heart to work harder to circulate the blood.

Blood pressure is categorized as normal, elevated, or stage 1 or stage 2 high blood pressure:

• Normal blood pressure is systolic of less than 120 and diastolic of less than 80

• Elevated blood pressure is systolic of 120 to 129 and diastolic less than 80

• Stage 1 high blood pressure (called stage 1 hypertension) is systolic is 130 to 139 or diastolic between 80 to 89

• Stage 2 high blood pressure (called stage 2 hypertension) is when systolic is 140 or higher or the diastolic is 90 or higher

These numbers should be used as a guide only. A single blood pressure measurement that is higher than normal does not necessarily mean there is a problem. Your healthcare provider will want to see multiple blood pressure measurements over several days or weeks before making a diagnosis of high blood pressure and starting treatment. Ask your provider when to contact them if your blood pressure readings are not within normal range.

Why should I monitor my blood pressure at home?

For people with high blood pressure, home monitoring allows your healthcare provider to monitor how much your blood pressure changes during the day, and from day to day. This may also help your provider determine how effectively your blood pressure medicine is working.

What special equipment do I need to measure blood pressure?

You can use either an aneroid monitor, which has a dial gauge and is read by looking at a pointer. Or you can use a digital monitor, in which the blood pressure reading flashes on a small screen. Whichever device you use, make sure the cuff fits your arm. Having a cuff that is too large or too small can lead to inaccurate readings.

Don't take your blood pressure on an arm or leg that has been severely injured, has had surgery on the blood vessels, or has injury to the tissue.

Before you measure your blood pressure

The American Heart Association recommends the following guidelines for home blood pressure monitoring:

• Don't smoke, have caffeinated drinks, or exercise for 30 minutes before taking your blood pressure.

• Go to the bathroom before the test.

• Relax for 5 minutes before taking the measurement.

• Sit with your back supported (don't sit on a couch or soft chair). Keep your feet on the floor uncrossed. Place your arm on a solid flat surface (like a table) with the upper part of the arm at heart level. Place the middle of the cuff directly above the bend of the elbow. Check the monitor's instruction manual for an illustration.

• Take multiple readings. When you measure, take 2 to 3 readings 1 minute apart and record all the results.

• Take your blood pressure at the same time every day, or as your healthcare provider recommends.

• Record the date, time, and blood pressure reading.

• Take the record with you to your next medical appointment. If your blood pressure monitor has a built-in memory, simply take the monitor with you to your next appointment.

• Call your provider if you have several high readings. Don't be frightened by a single high blood pressure reading, but if you get several high readings, check in with your healthcare provider.

• If your blood pressure reaches a systolic (top number) of 180 or higher OR diastolic (bottom number) of 120 or higher, seek emergency medical treatment now.

Ask your healthcare provider to teach you how to use your blood pressure monitor correctly. Have the monitor routinely checked for accuracy by taking it with you to your healthcare provider's office. It's also important to make sure the tubing is not twisted when you store it and keep it away from heat to prevent cracks and leaks. Monitors will have to be replaced now and then. Check that your device is working correctly.

Proper use of your blood pressure monitor will help you and your healthcare provider in monitoring your blood pressure.