Vital Signs

Original Editor - Manisha Shrestha Top Contributors - Manisha Shrestha

Original Editor - User Name

Top Contributors - Manisha Shrestha  


Vital signs are an objective measurement for the essential physiological functions of a living organism. It is named "vital" as their measurement and assessment is the critical first step for any clinical evaluation.[1]

Vital signs are indicators of one's health condition and the assurance of proper circulatory, respiratory, neural, and endocrinal functions. Vital signs are a mechanism to universally communicate a patient's condition and severity of the disease.[2] Vital signs are the simplest, cheapest, and probably the most important information gathered on hospitalized patients.[3]

Vital signs can be influenced by a number of factors. It can vary based on age, time, gender, medication, or a result of the environment. Thus, Healthcare providers must understand the various physiologic and pathologic processes affecting these sets of measurements and their proper interpretation.[1]

Importance of vital signs

  • Vital signs play an important role in emergency departments (ED) and on the wards, to determine patients at risk of deterioration.
  • The degree of vital sign abnormalities may also predict the long-term patient health outcomes, return emergency room visits, and frequency of readmission to hospitals, and utilization of healthcare resources. [1]
  • Vital signs help to predict physical therapy indications, contraindications, and outcomes.[4]
  • Vital signs are appropriate to characterize or quantify cardiovascular and pulmonary signs and symptoms as part of an assessment of aerobic capacity and endurance.[4]


Traditionally, vital signs consist of temperature, respiratory rate (RR). pulse rate (PR) and blood pressure (BP) but later oxygen saturation is added in it.

Body temperature

The normal body temperature for a healthy adult is approximately 98.6 degrees Fahrenheit/37.0 degrees centigrade. The human body temperature typically ranges from 36.5 to 37.5 degrees centigrade (97.7 to 99.5 degrees Fahrenheit).

Health care providers use the axillary, rectal, oral, and tympanic membrane most commonly used to record body temperature, and the electronic and infrared thermometers are the devices most commonly used.

Sites for measurement of body temperature

  1. Oral temperature: It is the most commonly used method, is considered very convenient and reliable. Here we place the thermometer under the tongue and close the lips around it. The posterior sublingual pocket is the area that gives the highest reliability.
  2. Tympanic temperature: In this method, the thermometer is inserted into the ear canal. This site is convenient but less accurate and hence not recommended.
  3. Axillary temperature: In this, we place the thermometer in the axilla while adducting the arm of the patient. This site is convenient but generally considered less accurate and hence not recommended.
  4. Rectal temperature: The thermometer is inserted through the anus into the rectum after applying a lubricant. This method is very inconvenient, but since it measures the internal measurement, it is very reliable. It is usually considered the "gold standard" method of recording temperature.
  5. Skin temperature: Digital thermometer can be used to measure the quick temperature from the skin of the forehead. It has been widely used now in this COVID-19 pandemic to avoid cross-contamination as the thermometer is kept 3-5cm away from the patient's forehead.

Body temperature is affected is by many sources of internal and external variables. Besides the site of measurement, the time of day is an essential factor leading to variability in the temperature record, secondary to the circadian rhythm. Other factors influencing body temperature are gender, recent activity,  a person's relative physical fitness, food, and fluid consumption, and, in women, the stage of the menstrual cycle. [1]

Pulse Rate

Pulse rate is defined as is the wave of blood in the artery created by contraction of the left ventricle during a cardiac cycle. The most common sites of measuring the peripheral pulses are the radial pulse, ulnar pulse, brachial pulse in the upper extremity, and the posterior tibialis or the dorsalis pedis pulse as well as the femoral pulse in the lower extremity. Clinicians also measure the carotid pulse in the neck. In day to day practice, the radial pulse is the most frequently used site for checking the peripheral pulse, where the pulse is palpated on the radial aspect of the forearm, just proximal to the wrist joint. 

Parameters for assessment of pulse

  1. Rate: The normal range used in an adult is between 60 to 100 beats /minute with rates above 100 beats/minute and rates and below 60 beats per minute, referred to as tachycardia and bradycardia, respectively. Changes in the rate of the pulse, along with changes in respiration is called sinus arrhythmia. In sinus arrhythmia, the pulse rate becomes faster during inspiration and slows down during expiration.
  2. Rythym: Assessing whether the rhythm of the pulse is regular or irregular is essential. The pulse could be regular, irregular, or irregularly irregular. Irregularly irregular pattern is more commonly indicative of processes like atrial flutter or atrial fibrillation.
  3. Volume: Assessing the volume of the pulse is equally essential. A low volume pulse could be indicative of inadequate tissue perfusion; this can be a crucial indicator of indirect prediction of the systolic blood pressure of the patient.
  4. Symmetry: Checking for symmetry of the pulses is important as asymmetrical pulses could be seen in conditions like aortic dissection, aortic coarctation, Takayasu arteritis, and subclavian steal syndrome.
  5. Amplitude and rate of increase:  Low amplitude and low rate of increase could be seen in conditions like aortic stenosis, besides weak perfusion states. High amplitude and rapid rise can be indicative of conditions like aortic regurgitation, mitral regurgitation, and hypertrophic cardiomyopathy.[1]

Respiratory Rate

The respiratory rate is the number of breaths per minute. Parameters that need to be include its rate, depth of breathing, and its pattern rate of breathing.

The normal breathing rate is about 12 to 20 beats per minute in an average adult. In the pediatric age group, it is defined by the particular age group.

Blood Pressure

Blood pressure is the force of circulating blood on the walls of the arteries, mainly in large arteries of the systemic circulation. Blood pressure is taken using two measurements: systolic (measured when the heartbeats, when blood pressure is at its highest) and diastolic (measured between heartbeats, when blood pressure is at its lowest). Blood pressure is written with the systolic blood pressure first, followed by the diastolic blood pressure.[5]

The direct measurement of BP requires an intra-arterial assessment but it is not practical in clinical practice so BP is measured via non-invasive means. Earlier BP is measure with a stethoscope while watching a sphygmomanometer (ie, auscultation). However, semiautomated and automated devices that use the oscillometry method, which detects the amplitude of the BP oscillations on the arterial wall, have become widely used over the past 2 decades.

The brachial artery is the most common site for BP measurement.

Key Points for Accurately Measuring BP

  • Appropriate cuff size.
  • Patient position: BP is mainly measured in the seated or supine position, regardless of the position of the patient, the BP cuff should be at the level of the patient’s right atrium. In the seated position, the right atrium level is the midpoint of the sternum or the fourth intercostal space.

Overview of Proper Seated BP Measurement in the Office

Key Steps for Proper BP Measurements Specific Instructions
Step 1: Properly prepare the patient 1. Have the patient relax, sitting in a chair with feet flat on the floor and back supported. The patient should be seated for 3–5 min without talking or moving around before recording the first BP reading. A shorter wait period is used for some AOBP devices.
2. The patient should avoid caffeine, exercise, and smoking for at least 30 min before measurement.
3. Ensure that the patient has emptied his/her bladder.
4. Neither the patient nor the observer should talk during the rest period or during the measurement.
5. Remove clothing covering the location of cuff placement.
6. Measurements made while the patient is sitting on an examining table do not fulfill these criteria.
Step 2: Use proper technique for BP measurements 1. Use an upper-arm cuff BP measurement device that has been validated, and ensure that the device is calibrated periodically.
2. Support the patient’s arm (eg, resting on a desk). The patient should not be holding his/her arm because isometric exercise will affect the BP levels.
3. Position the middle of the cuff on the patient’s upper arm at the level of the right atrium (midpoint of the sternum).
4. Use the correct cuff size such that the bladder encircles 75%–100% of the arm.
5. Use either the stethoscope diaphragm or bell for auscultatory readings.
Step 3: Take the proper measurements needed for diagnosis and treatment of elevated BP/hypertension 1. At the first visit, record BP in both arms.* Use the arm that gives the higher reading for subsequent readings.
2. Separate repeated measurements by 1–2 min.
3. For auscultatory determinations, use a palpated estimate of radial pulse obliteration pressure to estimate SBP. Inflate the cuff 20–30 mm Hg above this level for an auscultatory determination of the BP level.
4. For auscultatory readings, deflate the cuff pressure 2 mm Hg/s, and listen for Korotkoff sounds.
Step 4: Properly document accurate BP readings 1. Record SBP and DBP. If using the auscultatory technique, record SBP and DBP as the onset of the first of at least 2 consecutive beats and the last audible sound, respectively.
2. Record SBP and DBP to the nearest even number.
3. Note the time that the most recent BP medication was taken before measurements.
Step 5: Average the readings Use an average of ≥2 readings obtained on ≥2 occasions to estimate the individual’s BP.
Step 6: Provide BP readings to the patient Provide patients their SBP/DBP readings both verbally and in writing. Someone should help the patient interpret the results.

AOBP indicates automated office blood pressure; BP, blood pressure; DBP, diastolic blood pressure; and SBP, systolic blood pressure.

*When a BP measurement is obtained in 1 arm followed by the other arm and the BP is substantially lower in the second arm, it is possible that the difference could be caused by acclimation. In this circumstance, BP should be remeasured in the first arm.[6]

Normative value

According to the 2017 ACC/AHA Guideline for the Prevention, Detection, Evaluation, and Management of High BP in Adults.[6]

BP Category SBP, mm Hg DBP, mm Hg
Normal <120 and <80
Elevated 120–129 and <80
Stage 1 130–139 or 80–89
Stage 2 ≥140 or ≥90

Oxygen Saturation



  1. 1.0 1.1 1.2 1.3 1.4 Sapra A, Malik A, Bhandari P. Vital Sign Assessment. InStatPearls [Internet] 2019 Dec 28. StatPearls Publishing.
  2. Teixeira CC, Boaventura RP, Souza AC, Paranaguá TT, Bezerra AL, Bachion MM, Brasil VV. Vital signs measurement: an indicator of safe care delivered to elderly patients. Texto & Contexto-Enfermagem. 2015 Dec;24(4):1071-8.
  3. Brekke IJ, Puntervoll LH, Pedersen PB, Kellett J, Brabrand M. The value of vital sign trends in predicting and monitoring clinical deterioration: A systematic review. PloS one. 2019 Jan 15;14(1):e0210875.
  4. 4.0 4.1 Thistle VG, Basskin AL, Shamus E, Jeffreys-Heil R. Clinical decision making regarding the use of vital signs in physical therapy. Pediatrics. 2016;1:5-9.
  6. 6.0 6.1 Muntner P, Shimbo D, Carey RM, Charleston JB, Gaillard T, Misra S, Myers MG, Ogedegbe G, Schwartz JE, Townsend RR, Urbina EM. Measurement of blood pressure in humans: a scientific statement from the American Heart Association. Hypertension. 2019 May;73(5):e35-66.