[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Nursing](https://durgical.com/en/nursing/) › [Vital signs and assessment](https://durgical.com/en/nursing/areas/vitals/) › Measuring blood pressure correctly: cuff size, position and common errors # Measuring blood pressure correctly: cuff size, position and common errors - Assessment Blood pressure is measured with the right cuff size, the patient seated and rested, the arm supported at heart level and no talking. Updated Nov 5, 2026 ## Key points - Cuff too small: falsely high reading. Cuff too large: falsely low reading. - Cuff width: about 40 % of the arm circumference; bladder length: 80 to 100 % of it. - Seated, 5 minutes of rest, back supported, feet on the floor, legs uncrossed, arm supported at heart level, no talking. - Estimate the systolic by palpating the radial pulse, inflate about 30 mmHg above it and deflate at 2 to 3 mmHg per second. - Do not use an arm with a fistula, lymphoedema, a clot, a wound, a mastectomy or stroke deficits, or the arm with an IV line. - Caffeine or nicotine within 30 minutes raise the reading: wait, or record it with the value. ## What it is Almost all blood pressure errors are technique errors, and they shift the reading by several mmHg. A small cuff raises it; a large one lowers it; crossed legs, talking, recent caffeine or smoking also change it. If the cuff is not inflated high enough, the first sound can be missed and the systolic underestimated. Nurses control each step, repeat a value that does not fit and record the arm, position and method. ## Reference values - Normal: below 120/80 mmHg. Hypotension: below 90/60 mmHg. - Hypertension in adults: 130/80 mmHg or higher, diagnosed from an average of readings. - Stage 1: 130 to 139 or 80 to 89. Stage 2: 140 or more, or 90 or more. Crisis: above 180 or above 120. - Orthostatic hypotension: a fall of 20 mmHg or more systolic or 10 or more diastolic within 3 minutes of standing. ## What you need - Calibrated sphygmomanometer and cuffs in several sizes. - Stethoscope with a clean diaphragm. - A chair with a backrest and a support for the arm. - Knowing which arm cannot be used and whether the patient had coffee or smoked in the last 30 minutes. ## How to measure it (and why) - Seat the patient with back supported, feet on the floor and legs uncrossed, and allow 5 minutes of rest — exertion and posture change the reading. - Measure the arm and choose the cuff: width about 40 % and bladder length 80 to 100 % of the circumference — the wrong size is a common error. - Centre the bladder over the brachial artery, lower edge about 2.5 cm above the elbow crease, on bare skin — clothing and poor centring distort the reading. - Support the arm at heart level — an arm above or below that level changes the reading. - Find where the radial pulse disappears on inflation, deflate, wait 30 seconds, then inflate 30 mmHg above that point — so the first sound is not missed. - Deflate at 2 to 3 mmHg per second: the first sound is the systolic, the last the diastolic — deflating fast underestimates the systolic. - Ask the patient not to talk and do not talk yourself — talking changes the reading and makes the sounds hard to hear. - Record the value, arm, position, cuff size and whether manual or automatic — without context it cannot be compared. ## How to read it - In older adults Korotkoff sounds can be hard to hear; in stable patients a Doppler may help. - Caffeine, smoking and exercise in the previous 30 minutes raise the reading: ask and, if possible, wait. - Hypertension is not diagnosed from a single reading: readings on two or more occasions are averaged. - Blood pressure is not routinely measured in children under 3 unless there are cardiac concerns. - For orthostatic pressure, measure lying down and then standing within the next 3 minutes, watching for fall risk. ## Next step: when to call for help - Call if the value is outside the order's or protocol's parameters for this patient. - Call at once if an out-of-range value comes with symptoms such as severe headache, dizziness, light-headedness or fainting. - Call at once for a pressure below 90/60 mmHg with signs of poor perfusion, or dizziness on standing. - Record the confirming value, the symptoms and the time of the call. ## Test yourself Think of the answer, then tap the question to see it. ## What does a cuff that is too small do to the reading? It gives a falsely high reading; a cuff that is too large gives a falsely low reading. ## Why is the systolic estimated by palpation before listening? To know how high to inflate (30 mmHg above the point where the radial pulse disappears), so the first sound is not missed and the systolic is not underestimated. ## How fast is the cuff deflated? At about 2 to 3 mmHg per second; deflating faster misses the first sound and underestimates the systolic. ## Which arm is not used for blood pressure? An arm with a dialysis fistula, lymphoedema, a clot, a wound, a mastectomy or stroke deficits, or the arm with an IV line. ## What changes define orthostatic hypotension? A fall of 20 mmHg or more in systolic, or 10 mmHg or more in diastolic, within 3 minutes of standing. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/nursing/measuring-blood-pressure-correctly-cuff-size-position-and-common-errors/) ## Elsewhere in DurgiPedia - [Blood pressure measurement](https://durgical.com/en/clinical-exam/blood-pressure-measurement/) ## Connections ## Related 2 - [Vital signs in nursing: when, how often and how to record them](https://durgical.com/en/nursing/vital-signs-in-nursing-when-how-often-and-how-to-record-them/) - [Early warning scores (NEWS2) and when to escalate](https://durgical.com/en/nursing/early-warning-scores-and-when-to-escalate/) [← All of nursing](https://durgical.com/en/nursing/) Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order. Sources: [Nursing Skills (Open RN), 3.2 Blood Pressure Basics](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/03%3A_Blood_Pressure/3.02%3A_Blood_Pressure_Basics) (Open RN, Wisconsin Technical College System (LibreTexts), 2021); [Nursing Skills (Open RN), 3.3 Blood Pressure Assessment](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/03%3A_Blood_Pressure/3.03%3A_Blood_Pressure_Assessment) (Open RN, Wisconsin Technical College System (LibreTexts), 2021); [Nursing Skills (Open RN), 3.5 Checklist for Manual Blood Pressure](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/03%3A_Blood_Pressure/3.05%3A_Checklist_for_Manual_Blood_Pressure) (Open RN, Wisconsin Technical College System (LibreTexts), 2021); [Measuring Your Blood Pressure](https://www.cdc.gov/high-blood-pressure/measure/index.html) (Centers for Disease Control and Prevention, 2024). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/nursing/measuring-blood-pressure-correctly-cuff-size-position-and-common-errors/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/nursing/measuring-blood-pressure-correctly-cuff-size-position-and-common-errors/