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Vital signs

Vital signs is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Vital signs rather than just read about it. In short: Vital signs (also known as vitals) are a group of the four to six most crucial medical signs that indicate the status of the body's vital (life-sustaining) functions. These measurements are taken to help assess the general physical health of a person, give clues to possible diseases, and show progress toward recovery.

Vital signs — main illustration
Vital signs — illustration

Key takeaways

  • Vital signs belongs to physics; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Vital signs to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Vital signs from memory before moving on to harder problems.

Reference excerpt

Vital signs (also known as vitals) are a group of the four to six most crucial medical signs that indicate the status of the body's vital (life-sustaining) functions. These measurements are taken to help assess the general physical health of a person, give clues to possible diseases, and show progress toward recovery. The normal ranges for a person's vital signs vary with age, weight, gender, and overall health. There are four primary vital signs: body temperature, blood pressure, pulse (heart rate), and breathing rate (respiratory rate), often notated as BT, BP, HR, and RR. However, depending on the clinical setting, the vital signs may include other measurements called the "fifth vital sign" or "sixth vital sign". Early warning scores have been proposed that combine the individual values of vital signs into a single score. This was done in recognition that deteriorating vital signs often precede cardiac arrest and/or admission to the intensive care unit. Used appropriately, a rapid response team can assess and treat a deteriorating patient and prevent adverse outcomes.

Primary vital signs There are four primary vital signs which are standard in most medical settings:

Body temperature Heart rate or pulse Respiratory rate Blood pressure The equipment needed is a thermometer, a sphygmomanometer, and a watch. Although a pulse can be taken by hand, a stethoscope may be required for a clinician to take a patient's apical 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. Body temperature is maintained through a balance of the heat produced by the body and the heat lost from the body.

Temperature can be recorded in order to establish a baseline for the individual's normal body temperature for the site and measuring conditions. Temperature can be measured from the mouth, rectum, axilla (armpit), ear, or skin. Oral, rectal, and axillary temperature can be measured with either a glass or electronic thermometer. Note that rectal temperature measures approximately 0.5 °C higher than oral temperature, and axillary temperature approximately 0.5 °C less than oral temperature. Aural and skin temperature measurements require special devices designed to measure temperature from these locations. While 37 °C (99 °F) is considered "normal" body temperature, there is some variance between individuals. Most have a normal body temperature set point that falls within the range of 36.0 to 37.5 °C (96.8 to 99.5 °F). The main reason for checking body temperature is to solicit any signs of systemic infection or inflammation in the presence of a fever. Fever is considered temperature of 37.8 °C (100.0 °F) or above. Other causes of elevated temperature include hyperthermia, which results from unregulated heat generation or abnormalities in the body's heat exchange mechanisms. Temperature depression (hypothermia) also needs to be evaluated. Hypothermia is classified as temperature below 35 °C (95 °F). It is also recommended to review the trend of the patient's temperature over time. A fever of 38 °C does not necessarily indicate an ominous sign if the patient's previous temperature has been higher.

Pulse

The pulse is the rate at which the heart beats while pumping blood through the arteries, recorded as beats per minute (bpm). It may also be called "heart rate". In addition to providing the heart rate, the pulse should also be evaluated for strength and obvious rhythm abnormalities. The pulse is commonly taken at the wrist (radial artery). Alternative sites include the elbow (brachial artery), the neck (carotid artery), behind the knee (popliteal artery), or in the foot (dorsalis pedis or posterior tibial arteries). The pulse is taken with the index finger and middle finger by pushing with firm yet gentle pressure at the locations described above, and counting the beats felt per 60 seconds (or per 30 seconds and multiplying by two). The pulse rate can also be measured by listening directly to the heartbeat using a stethoscope. The pulse may vary due to exercise, fitness level, disease, emotions, and medications. The pulse also varies with age. A newborn can have a heart rate of 100–⁠160 bpm, an infant (0–⁠5 months old) a heart rate of 90–⁠150 bpm, and a toddler (6–⁠12 months old) a heart rate of 80–140 bpm. A child aged 1–⁠3 years old can have a heart rate of 80–⁠130 bpm, a child aged 3–⁠5 years old a heart rate of 80–⁠120 bpm, an older child (age of 6–10) a heart rate of 70–⁠110 bpm, and an adolescent (age 11–⁠14) a heart rate of 60–105 bpm. An adult (age 15+) can have a heart rate of 60–100 bpm.

Respiratory rate

Average respiratory rates vary between ages, but the normal reference range for people age 18 to 65 is 16–20 breaths per 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 a clear indicator of acidotic states, as the main function of respiration is removal of CO2 leaving bicarbonate base in circulation.

Blood pressure

… excerpt ends here. Continue reading the full article.

Illustrations

Vital signs illustration
Vital signs: Oral glass thermometer showing a body temperature in °F
Oral glass thermometer showing a body temperature in °F
Vital signs: An individual taking their own radial pulse
An individual taking their own radial pulse
Vital signs: Manual sphygmomanometer and stethoscope used to take blood pressure in clinic
Manual sphygmomanometer and stethoscope used to take blood pressure in clinic

Worked examples

Example 1 — a first encounter with Vital signs

Start with the simplest possible case. Write down what Vital signs claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Vital signs before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Vital signs ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Vital signs

In research
Vital signs appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Vital signs in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Vital signs is common in secondary-school and first-year university syllabi. It links to neighbouring topics Medical signs, Physical examination, so understanding it makes those chapters shorter.
In everyday life
Look for Vital signs outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Vital signs in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Vital signs means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Vital signs out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Vital signs in simple terms?

Vital signs (also known as vitals) are a group of the four to six most crucial medical signs that indicate the status of the body's vital (life-sustaining) functions. These measurements are taken to help assess the general physical health of a person, give clues to possible diseases, and show progr…

Why does Vital signs matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Vital signs?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Vital signs.

Tags

  • Medical signs
  • Physical examination

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