Doctors measure vital signs, like blood pressure, heart rate, and temperature, to understand how a body is functioning and to detect and monitor health issues.
Vital signs are measurements of the body’s basic functions. The vital signs doctors typically measure and monitor are:
- body temperature
- heart rate (the rate of your heartbeat)
- respiratory rate (rate of breathing)
- blood pressure
- oxygen saturation (the amount of oxygen circulating in your blood)
Vital signs are useful in detecting or monitoring health issues and alerting medical professionals to potential concerns.
In this article, we explore what vital signs are, how they’re measured, and what they can tell us about our health.
Measuring vital signs is usually the first step in almost every medical evaluation. Doctors use these measurements to better understand how a person’s body is functioning and to detect possible health concerns.
By monitoring a person’s vital signs consistently, such as at every health checkup, a doctor can establish a baseline for that person. Vital signs can then act as early warning flags. For example, a change in a person’s baseline measurements might point to an underlying illness or heart issue that has not yet been diagnosed.
What factors affect vital signs?
Vital signs can fluctuate or change when a person is sick, taking certain medications, or experiencing pain, anxiety, or stress. A person’s age or a change in lifestyle can also affect one or more vital signs.
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Your heart rate, or pulse, measures the number of times your heart beats each minute. A heart rate can help a doctor understand your heart rhythm and how strong your pulse is.
The normal heart rate for a healthy adult ranges from 60 to 100 beats per minute. The rate can change depending on the circumstances. For example, it may increase when you’re exercising and decrease when taking certain medications. Athletes often have lower heart rates than nonathletes.
People assigned female at birth tend to have slightly higher heart rates than people assigned male at birth.
How to measure your pulse
For most people, it’s easiest to measure your heart rate at the wrist. Here are the steps to take:
- Using your first and second fingertips, press gently on the arteries that run beneath the skin of your wrist (just below your hand) until you feel a pulse.
- Have a clock nearby and begin counting your pulse when the clock’s second hand is on the 12.
- Count your pulse for 15 seconds, and then multiply that number by 4 to calculate the number of beats per minute.
- It may be worthwhile to repeat the count to see whether you get the same number.
- If you’re unsure about your results or keep getting different results, ask someone to count or watch the clock for you.
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A respiratory rate is the number of breaths a person takes each minute. The rate is usually measured when a person is resting rather than under duress or in a stressful situation. However, in emergencies, healthcare teams often measure the respiratory rate to monitor what’s happening in the body at that moment.
Like other vital signs, a respiratory rate may increase with fever, illness, or other medical conditions or circumstances.
A normal respiratory rate for a healthy adult typically ranges from 12 to 16 breaths per minute. To measure your respiratory rate, count the number of breaths or times you inhale for 15 seconds and multiply that number by 4.
A normal body temperature can vary depending on your sex assigned at birth, recent activity, food and fluid consumption, time of day, and, in people who menstruate, the stage of the menstrual cycle.
For adults, normal body temperatures can range from 97.8°F to 99°F (36.5°C to 37.2°C).
A body temperature can be measured in any of the following ways:
- Orally: Either a glass thermometer or a digital thermometer that uses an electronic probe can measure body temperature from the mouth.
- Rectally: Temperatures taken rectally using a glass or digital thermometer tend to be a bit higher than when taken by mouth.
- Axillary: Temperatures taken under the arm using a glass or digital thermometer tend to be a bit lower than temperatures taken by mouth.
- By ear: A special thermometer can quickly measure the temperature of the eardrum, which reflects the body’s temperature.
- By skin: A special thermometer can quickly measure the temperature of the skin on the forehead.
What is a fever?
A fever is when body temperature rises to a level that’s higher than normal. In general, you have a fever if your temperature is:
- In adults: higher than 99°F to 99.5°F (37.2°C to 37.5°C)
- In children: higher than 99.5°F (37.5°C)
- In infants: higher than 100.4°F (38°C)
Fevers are often short-term increases in body temperature that help your body fight infection or illness. However, a severe or sustained fever can indicate a more serious condition that warrants medical attention.
Contact a doctor if you have a fever above 100.4°F (38°C) that lasts for more than 3 days.
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Oxygen saturation is the amount of oxygen in your blood. Because the body’s organs and tissues need oxygen to work, oxygen must travel through the bloodstream to help support the functions of the body.
For most healthy adults, a normal oxygen saturation level is between 95% and 100%. Anything below 95% means your body isn’t receiving enough oxygen and needs medical attention.
You can check your oxygen saturation rate at home with a device called a pulse oximeter. You can purchase a pulse oximeter at most stores that carry health-related items.
To use, simply insert your fingertip into the small device. You will feel a slight pressure, but it does not squeeze your fingertip or cause pain. Most devices will beep or stop flashing when the reading is complete.
If you have any questions, you can talk with a healthcare professional about how to use your pulse oximeter and understand the readings. Some factors
- darker skin tones
- nail polish
- cold fingers
Blood pressure is the force used to move blood through the cardiovascular system. With every heartbeat, blood is pumped into the arteries. Pressure is at its highest when the heart contracts and at its lowest when the heart relaxes.
Blood pressure is measured in millimeters of mercury (mm Hg) with two numbers:
- Systolic pressure (top number): when the heart contracts
- Diastolic pressure (bottom number): when the heart relaxes
Healthcare professionals generally use four categories to define blood pressure readings in adults:
- Healthy: The systolic number is 120 or less, and the diastolic number is 80 or less.
- Elevated: The systolic number is between 120 and 129, and the diastolic number is less than 80.
- Stage 1 hypertension: The systolic number is between 130 and 139, or the diastolic number is between 80 and 89.
- Stage 2 hypertension: The systolic number is 140 or higher, or the diastolic number is 90 or higher.
High blood pressure (hypertension)
High blood pressure can be a sign of a serious or even life threatening illness.
Since high blood pressure usually
This can be done at your doctor’s office. Many pharmacies also have computerized blood pressure monitoring equipment to help you monitor your pressure between doctors’ appointments.
If you have a family history of heart disease or other risk factors, your doctor may recommend that you have your blood pressure checked at least twice a year.
Your doctor might also talk with you about monitoring your blood pressure at home. This helps your healthcare team monitor the changes in your blood pressure from day to day. It can also help them determine whether a medication is working properly.
Monitoring blood pressure at home
Blood pressure can be measured by an aneroid monitor or a digital monitor. An aneroid monitor has a dial gauge and is read by looking at a pointer, similar to the face of a compass.
A digital monitor flashes the measurement on a screen, typically in red numbers. The digital monitor is automatic. Because the recordings are easy to read, this is the most popular blood pressure measuring device. But they’re also more expensive.
Blood pressure cuffs that go around the upper arm are more accurate than those that go around a wrist or finger.
How to measure your blood pressure at home
Here is how you can take an accurate blood pressure reading at home:
- Make sure you have not had a caffeinated drink, like coffee or tea, at least 1 hour before taking the measurement.
- Do not smoke for at least 15 minutes before taking the measurement.
- A full bladder can offset the pressure reading, so be sure to use the bathroom before the measurement.
- Sit comfortably for at least 5 minutes before checking your pressure. It’s best not to engage in conversation while your pressure is being taken.
- Make sure your back feels supported and that your legs are uncrossed with your feet firmly on the ground.
- Your arm should be resting and supported at the same level as your heart.
- It’s best to check the blood pressure in both arms to verify an accurate reading.
If you see that the systolic (top) number is 180 or higher or if the diastolic (bottom) number is 110 or higher, seek emergency medical treatment.
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Be sure to take your blood pressure at the same time every day and record the date, time, and reading. Call your doctor’s office if you notice you have several high readings. It can sometimes be normal to have high readings, but your doctor is the one who can determine whether there is a concern.
Remember to take a copy of your blood pressure readings to every appointment with your doctor. It’s also important to take your blood pressure equipment with you so the healthcare staff can make sure the equipment is in proper working order.
Just like adults, vital signs for children include heart rate, respiratory rate, body temperature, and blood pressure. Knowing the normal ranges of vital signs for your child can help you notice problems or relieve concerns you may have if your child is not feeling well.
The table below lists normal vital signs in infants, children, and teenagers:
| Vital signs | Infant (0–12 months) | Child (1–11 years) | Teenager (12 years and up) |
|---|---|---|---|
| Heart rate | 100–160 bpm | 70–20 bpm | 60–100 bpm |
| Respiratory rate | 0 to 6 months: 30–60 bpm 6 to 12 months: 24–30 bpm | 1 to 5 years: 20–30 bpm 6 to 11 years: 12–20 bpm | 12–18 bpm |
| Blood pressure | 0 to 6 months: 65 to 90/45 to 65 mm Hg 6 to 12 months: 80 to 100/55 to 65 mm Hg | 90 to 110/55 to 75 mm Hg | 110 to 135/65 to 85 mm Hg |
| Temperature | all ages: 98.6°F (37°C) normal range: 97.4°F–99.6°F (36.3°C–37.5°C) | all ages: 98.6°F (37°C) normal range: 97.4°F–99.6°F (36.3°C–37.5°C) | all ages: 98.6°F (37°C) normal range: 97.4°F–99.6°F (36.3°C–37.5°C) |
Vital signs measure the body’s basic functions. These include your temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation.
At almost every healthcare appointment, a doctor, nurse, or another member of the healthcare team will take your vital signs and record them.
It’s important to establish and record baseline measurements. A doctor can use these measurements to notice changes that might indicate an illness or other health concern that needs investigating.
