What is Blood Pressure?
Blood pressure (BP) is the force of circulating blood on the artery walls, measured as systolic (during heart contraction) and diastolic (during relaxation). A BP of 120/80 mmHg means a systolic of 120 mmHg and a diastolic of 80 mmHg. It reflects how well the heart pumps and how elastic the arteries are. Nurses measure BP to establish a baseline, monitor hemodynamic status, and detect changes. Consistently abnormal BP can indicate hypertension (high) or hypotension (low).
Importance of Monitoring Blood Pressure
- Early detection of hypertension, the "silent killer," which damages the heart, brain, kidneys, and vessels for years without symptoms.
- Prevention of cardiovascular events. High BP is a major risk factor for heart disease, stroke, heart attack, and heart failure.
- Monitoring response to treatment, tracking trends to adjust medications or lifestyle changes.
- Detecting hypotension and other conditions causing dizziness, fainting, or poor organ perfusion, from dehydration, medication, or blood loss.
- Guiding clinical decision-making on medications, fluid management, and procedures.
Normal Regulation: Cardiac Output and Peripheral Resistance
BP is a balance of cardiac output (CO) and peripheral vascular resistance (PVR). Cardiac output is the blood pumped per minute, determined by heart rate and stroke volume; when it increases (exercise, stress), BP rises. Peripheral resistance is the resistance in small arteries and arterioles, set by vessel diameter: vasoconstriction raises resistance and BP, vasodilation lowers them. The autonomic nervous system and hormones like adrenaline and angiotensin II keep BP in a healthy range.
Components of Blood Pressure
Systolic pressure is the maximum pressure when the ventricles contract and push blood out. A higher systolic can indicate increased cardiac workload or narrowed arteries.
Diastolic pressure is the minimum pressure when the ventricles rest and fill between beats. Elevated diastolic suggests persistent vascular resistance; low diastolic may signal poor vascular tone.
Mean Arterial Pressure (MAP)
MAP is the average arterial pressure during one cardiac cycle, a better measure of organ perfusion pressure than systolic or diastolic alone.
Formula: MAP = (Systolic BP + 2 × Diastolic BP) / 3.
For a BP of 120/80 mmHg: MAP = (120 + (2 × 80)) / 3 = (120 + 160) / 3 = 280 / 3 = 93.33 mmHg.
Normal range: 70 and 100 mmHg, important for perfusing the brain, kidneys, and heart.
- Low MAP (< 70 mmHg): may suggest hypoperfusion and organ dysfunction.
- High MAP (> 100 mmHg): may indicate hypertension and end-organ damage risk.
Determinants of Blood Pressure
- Cardiac output: heart rate × stroke volume; higher output raises BP.
- Peripheral resistance: set by vessel diameter (vasoconstriction raises it), blood viscosity, and vessel length.
- Blood volume: higher volume raises BP, lower volume lowers it.
- Blood viscosity: higher viscosity (e.g., high red cell count) raises resistance and BP.
- Elasticity of arterial walls: lost elasticity (arteriosclerosis) raises systolic pressure.
- Neural factors: the sympathetic nervous system raises BP; the parasympathetic lowers it.
- Hormonal factors: the renin-angiotensin-aldosterone system (RAAS), where angiotensin II causes vasoconstriction and aldosterone increases sodium and water retention; antidiuretic hormone (ADH), which promotes water retention; and adrenaline and noradrenaline, which raise heart rate and cause vasoconstriction.
- Renal regulation: the kidneys control blood volume through fluid excretion or retention.
What is Normal Blood Pressure?
The American Heart Association defines normal BP as systolic less than 120 mmHg and diastolic less than 80 mmHg, expressed as 120/80 mmHg (AHA). The category thresholds below follow the 2017 ACC/AHA Hypertension Guideline. Readings consistently above or below require medical evaluation.
| Factor | Explanation |
|---|---|
| Age | Blood vessels stiffen with age, raising peripheral resistance and BP. Children generally have lower BP than adults. |
| Gender | Men usually have higher BP than women before midlife; post-menopausal women often have higher BP due to decreased estrogen . |
| Activity and Exercise | Physical exertion raises BP temporarily but lowers baseline BP over time by improving heart and vessel health. |
| Emotions and Stress | Fear, anxiety, stress, or pain trigger the sympathetic nervous system, increasing heart rate and vasoconstriction, which raises BP. |
| Body Position | BP is typically lower when lying down and higher when sitting or standing because of gravity’s effect on blood flow and vessel tone. |
| Medications | Antihypertensives, diuretics, and sedatives lower BP; stimulants, decongestants, or NSAIDs may increase BP. |
| Time of Day | BP dips during sleep and is lowest in early morning, rising throughout the day and peaking in late afternoon or evening due to natural circadian rhythms. |
| Smoking and Alcohol | Nicotine causes vasoconstriction, raising BP; excessive or chronic alcohol use can elevate BP long-term. |
| Body Weight | Excess weight increases blood volume and cardiac workload, often resulting in higher BP. |
| Illness/Health Conditions | Fever, infections, pain, or chronic diseases (e.g., heart failure, kidney disease) alter fluid balance, cardiac output, or vessel resistance, affecting BP. |
| Temperature | Fever raises metabolic rate and cardiac output, often increasing BP; prolonged cold exposure can cause vasoconstriction, raising BP temporarily. |
| Pain | Acute pain activates the sympathetic nervous system, causing vasoconstriction and a rise in BP; untreated severe pain may keep BP elevated. |
| Dietary Factors | High sodium intake raises BP by increasing fluid retention; a balanced diet rich in potassium, calcium, and low in processed foods can help maintain normal BP. |
| Category | Systolic (mm Hg) | Diastolic (mm Hg) |
|---|---|---|
| Normal | <120 | <80 |
| Elevated | 120-129 | <80 |
| Hypertension Stage 1 | 130-139 | 80-89 |
| Hypertension Stage 2 | ≥140 | ≥90 |
| Hypertensive Crisis | >180 | >120 |
Types and Methods of Measurement
- Manual auscultation (Korotkoff sounds): the gold standard, using a sphygmomanometer and stethoscope. The first sound is systolic; the disappearance of sound is diastolic.
- Automated monitoring: electronic devices inflate the cuff and detect oscillations, convenient for quick repeatable readings but less reliable with irregular heartbeats.
- Palpation method: feeling for the radial or brachial pulse return during deflation, giving systolic only, useful when sounds are hard to hear.
- Doppler method: an ultrasound probe amplifies blood flow sounds when pulses are weak, giving a reliable systolic reading.
- Ambulatory and home monitoring: ambulatory monitoring (ABPM) takes readings over 24 hours to detect white coat hypertension and variability; home monitoring tracks BP outside the clinic.
| Method | Description | Advantages | Limitations |
|---|---|---|---|
| Manual Auscultation | Uses sphygmomanometer and stethoscope to listen for Korotkoff sounds. | Gold standard; accurate when done correctly; allows assessment of both systolic & diastolic BP. | Requires skill, training, and a quiet environment; can be hard with faint sounds or noisy settings. |
| Automated BP Monitoring | Uses electronic device to detect BP via oscillometric method. | Quick, easy, good for repeated readings; reduces observer error; ideal for self-monitoring. | Can be inaccurate with arrhythmias or improper cuff placement; calibration needed. |
| Palpation Method | Feel for return of pulse while deflating cuff to estimate systolic pressure only. | Useful when sounds are inaudible; simple; requires minimal equipment. | No diastolic value obtained; less precise; not suitable for routine full BP assessment . |
| Doppler Method | Uses ultrasound probe to detect blood flow sounds when pulses are weak. | Good for low BP, poor perfusion, children, or obese arms; more sensitive than palpation alone. | Provides only systolic pressure; requires Doppler device and gel; needs practice. |
| Ambulatory/Home Monitoring | Wearable device for 24-hour or home BP checks outside clinical setting. | Detects white coat hypertension ; shows daily BP patterns; empowers patient self-management. | More costly; patient must follow instructions; potential discomfort wearing the cuff repeatedly. |
Step-by-Step: Manual (Auscultatory) Measurement
1. Verify provider orders and gather equipment.
2. Collect a properly sized cuff, an aneroid or mercury sphygmomanometer, and a stethoscope, since correct cuff size and calibrated equipment reduce errors.
3. Wash hands.
4. Ensure comfort and privacy, since anxiety falsely elevates BP.
5. Identify the patient using two identifiers.
6. Explain the procedure in simple terms to gain cooperation.
7. Position the patient sitting or lying, arm bare and supported at heart level, palm up, feet flat (if sitting), back supported, legs uncrossed. An unsupported arm or crossed legs can cause falsely high readings. Allow a few minutes of rest if the patient was active.
8. Wrap the cuff snugly, lower edge about 1 inch (2–3 cm) above the antecubital fossa, with the artery marker over the brachial artery, and confirm the cuff size is appropriate.
9. Palpate the brachial pulse and inflate (palpatory estimate). Inflate while feeling the brachial pulse, note where the pulse disappears (approximate systolic), continue 20–30 mmHg beyond, then slowly deflate and wait ~30 seconds. This estimates systolic and helps avoid missing an auscultatory gap.
10. Position the stethoscope diaphragm (or bell) firmly over the brachial artery, below the cuff edge on bare skin, not under the cuff.
11. Inflate to 20–30 mmHg above the palpated systolic estimate.
12. Deflate at 2–3 mmHg per second while listening.
13. Identify Korotkoff sounds. Note the manometer reading at the first tapping sound (systolic). Note the reading when sounds disappear completely (diastolic in adults). In children, Phase 4 muffling is often used. Watch for an auscultatory gap.
14. Complete deflation, release remaining air, and remove the cuff. If repeating, wait about 1–2 minutes to avoid venous congestion.
15. Clean the stethoscope earpieces and diaphragm and perform hand hygiene.
16. Record BP as systolic/diastolic in mmHg, the arm, position, and observations (e.g., "Right arm, seated, BP 120/78 mmHg"). Verify an abnormal reading per protocol and inform the provider.
Tips: keep the environment quiet; use the correct cuff size (or thigh/pediatric cuff); avoid pressing the stethoscope too firmly; use the same arm for repeats; have the patient avoid caffeine, exercise, or smoking for at least 30 minutes; and average multiple readings if needed.
Step-by-Step: Automated Measurement
1. Check the order and verify the patient with two identifiers.
2. Collect an appropriately sized monitor with a working power source, since an incorrect cuff size skews readings (too small reads high, too large reads low).
3. Wash hands.
4. Introduce yourself and explain that the cuff will inflate tightly but harmlessly.
5. Ensure comfort and privacy.
6. Seat the patient with back supported, feet flat, legs uncrossed, arm bare and supported at heart level, palm up.
7. Wrap the cuff about 1 inch (2–3 cm) above the antecubital fossa, artery marker over the brachial artery.
8. Place the device on a stable surface with the display visible and tubing unkinked.
9. Ask the patient to sit quietly, not talking or moving.
10. Press start and observe the inflation and deflation.
11. Monitor for discomfort, excessive pressure, or error codes.
12. If the reading seems inconsistent, wait 1–2 minutes and repeat.
13. Remove the cuff and settle the patient.
14. Wipe the cuff and monitor per policy.
15. Wash hands.
16. Record the reading, arm, position, device, and observations (e.g., "Left arm, seated, automated BP: 124/78 mmHg, patient calm").
Tips: always verify an unusual automated reading with a manual one; teach proper home use; follow calibration policies; check cuff fit; ensure the patient is calm and still for at least 5 minutes; and repeat if an error appears.
Step-by-Step: Palpatory Method
1. Confirm the order and verify with two identifiers.
2. Collect a properly sized cuff and sphygmomanometer, with clean hands.
3. Wash hands and ensure privacy.
4. Position the patient with the arm supported at heart level, palm up, relaxed.
5. Find the radial pulse with the index and middle fingers.
6. Wrap the cuff about 2–3 cm above the antecubital fossa, bladder centered over the brachial artery.
7. Inflate until the radial pulse disappears, then 20–30 mmHg higher.
8. Deflate slowly (2–3 mmHg per second) and note where the pulse returns, the palpated systolic pressure.
9. Release remaining air and remove the cuff.
10. Wash hands and document the palpated systolic (e.g., "BP by palpation: 110/P," P meaning palpated), with the arm and position.
As the cuff inflates, the pulse disappears when the artery is fully occluded; the actual systolic is where the pulse reappears on slow deflation. If the pulse disappeared at 100 mmHg during inflation but returned at 105 mmHg during deflation, use 105 mmHg.
Tips: correct cuff size; arm at heart level; find the radial pulse with fingertips, never the thumb; inflate 20–30 mmHg above where the pulse disappears; deflate slowly; document as "systolic/P" (e.g., 104/P); and use palpation first when Korotkoff sounds are hard to hear.
Step-by-Step: Doppler Method
Used when pulses are faint or sounds inaudible (severe hypotension, peripheral vascular disease, obesity).
1. Check the order for frequency, site, and instructions.
2. Collect a Doppler device with gel, BP cuff, stethoscope (optional), and alcohol wipes.
3. Wash hands, explain the procedure, and provide privacy.
4. Position the patient with the arm at heart level, palm up, and expose the artery site (brachial, radial, or popliteal).
5. Wrap the cuff about 2–3 cm above the probe site.
6. Apply ultrasound gel over the artery.
7. Hold the probe at a 45-degree angle with light pressure until you hear the whooshing blood flow.
8. Inflate 20–30 mmHg above the point where the sound disappears.
9. Deflate slowly and note where the sound reappears, the systolic pressure.
10. Remove gel from skin and probe.
11. Record the systolic BP, limb, site, and method (e.g., "Doppler BP: Right arm, brachial, 90/P mmHg").
Tips: use enough gel; hold the probe at a 45-degree angle; press lightly; keep the room quiet; inflate 20–30 mmHg past where the sound stops; Doppler gives systolic only (write "120/P"); and clean the probe and skin after.
Ambulatory and Home Monitoring
1. Verify the physician order if required.
2. Explain the purpose and procedure.
3. Select a validated, properly sized device.
4. Teach proper cuff placement, snug, level with the heart, on a bare arm.
5. Teach correct body position, back supported, feet flat, arm at heart level.
6. Explain frequency, often twice in the morning and evening for several days; ambulatory monitors record automatically over 24 hours.
7. Advise resting quietly for 5 minutes and avoiding caffeine, smoking, or exercise 30 minutes beforehand.
8. Show how to record or transfer results.
9. Discuss when to report abnormal results.
10. Document the education provided.
Tips for patients: use a validated upper-arm device (wrist and finger devices are less reliable); check cuff size and placement about an inch above the elbow crease; rest 5 minutes before measuring; avoid smoking, caffeine, or exercise within 30 minutes and don't talk; take at least two readings a minute apart and average them; keep a log; for a 24-hour ambulatory monitor keep the cuff on and stay still with the arm relaxed when it inflates; and bring the monitor to appointments.
Interpretation and Categories
BP is recorded as systolic/diastolic in mmHg. The systolic is the first Korotkoff sound (Phase 1); the diastolic is when the sounds disappear (Phase 5). For example, if tapping starts at 128 mmHg and disappears at 76 mmHg, record 128/76. In some children, muffling (Phase 4) marks the diastolic.
Confirm a diagnosis with measurements on at least two separate occasions, ideally different days (per the 2017 ACC/AHA Hypertension Guideline). Normal BP means generally low cardiovascular risk; elevated BP warrants lifestyle changes; Stage 1 hypertension calls for lifestyle changes plus possible medication; Stage 2 usually requires both; and a hypertensive crisis with signs of organ damage (chest pain, stroke symptoms) is an emergency.
| Korotkoff Phase | Description | Significance |
|---|---|---|
| Phase 1 (K₁) | First appearance of clear, sharp tapping sounds. | Indicates systolic pressure -the point where blood just starts to flow through the compressed artery . |
| Phase 2 (K₂) | Sounds become softer, swishing, or whooshing. | Turbulent blood flow as cuff deflates between systolic and diastolic pressures. |
| Phase 3 (K₃) | Sounds become crisper and louder, like louder tapping or thumping. | Blood flow is less turbulent than K₂ but still not fully smooth. |
| Phase 4 (K₄) | Sounds take on a muffled, soft, blowing quality. | Blood flow becomes smoother; muffling sometimes used for diastolic in children. |
| Phase 5 (K₅) | Complete disappearance of sounds (silence). | Indicates diastolic pressure in most adults-point where blood flow is smooth, without turbulence. |
Hypotension
- Systolic BP < 90 mmHg or diastolic BP < 60 mmHg is generally hypotensive for most adults.
- "Low" depends on the usual BP; athletes may have BP around 90/60 mmHg with no symptoms.
- Low BP with dizziness, fainting, weakness, or shock signs is clinically significant.
Orthostatic (Postural) Hypotension
- A drop of ≥20 mmHg systolic or ≥10 mmHg diastolic within 3 minutes of standing, compared to lying.
- Usually with dizziness, lightheadedness, or syncope.
- Check by measuring BP and heart rate lying, then sitting or standing. Common in older adults, dehydrated patients, and those on BP-lowering medications or diuretics.
Korotkoff Sounds
Named after Dr. Nikolai Korotkoff, these are produced by turbulent blood flow as cuff pressure changes. Five phases:
- Phase 1 (K₁): first clear tapping sounds, indicating systolic pressure.
- Phase 2 (K₂): softer, swishing sounds as flow increases.
- Phase 3 (K₃): crisper, louder thumping as the artery opens more.
- Phase 4 (K₄): muffled, soft, blowing quality as flow becomes laminar. In pediatrics, the muffling point is often taken as diastolic.
- Phase 5 (K₅): silence, when sounds disappear; the last sound before silence is the diastolic pressure.
In high cardiac output states (fever, pregnancy) or severe aortic regurgitation, sounds may continue to zero with no distinct Phase 5; some clinicians then record Phase 4 muffling (e.g., "BP 130/, /70 mmHg (Phase 4 muffling at 70)"). Deflate at ~2 mmHg per second so sounds are not missed.
An auscultatory gap is when Phase 1 sounds start, disappear, then reappear; mistaking the reappearance for systolic causes large underestimation. Use palpation first and listen well below diastolic. Document a gap (e.g., "auscultatory gap from 140 to 120 mmHg").
Common Errors
| Error in Technique | Effect on Reading | How to Avoid |
|---|---|---|
| Cuff too narrow or small | Falsely HIGH reading | Use appropriate larger cuff (bladder width = ~40% of arm, length = 80% of arm) |
| Cuff too wide or large | Falsely LOW reading | Use a correctly sized smaller cuff for the arm |
| Cuff wrapped too loosely or unevenly | Falsely HIGH reading | Wrap cuff snugly, with equal tension, removing bulky clothing |
| Arm unsupported (hanging down) | Falsely HIGH reading | Support the arm at heart level (use a table or pillow) |
| Arm positioned above heart level | Falsely LOW reading | Keep the cuff at the level of the heart (mid- sternum) |
| Arm positioned below heart level | Falsely HIGH reading | Same as above-adjust arm to heart level |
| Insufficient rest before measurement (patient not relaxed) | Falsely HIGH | Have patient sit quietly for 5 minutes before taking BP |
| Repeating measurement too quickly (no rest between) | False HIGH systolic or false LOW diastolic | Wait 1-2 minutes between repeated measurements on the same limb |
| Deflating cuff too quickly | False LOW systolic and false HIGH diastolic | Deflate slowly (~2-3 mmHg per second) to hear onset and disappearance of sounds clearly |
| Deflating cuff too slowly | False HIGH diastolic (venous congestion) | Do not pause or excessively slow the deflation; maintain recommended rate |
| Stethoscope pressure too firm on artery | False LOW diastolic (sounds persist) | Apply stethoscope with light pressure (especially bell) |
| Failure to detect auscultatory gap | False LOW systolic or false LOW diastolic | Use palpation to estimate systolic first; listen thoroughly until cuff fully deflated |
| Observer error (e.g., parallax misreading gauge, rounding) | Varies (can be high or low) | Get at eye level with aneroid gauge; use automated devices if unsure; practice for consistency |
| Cuff over clothing or rolled sleeve that’s tight | Falsely HIGH reading (or no sound) | Wrap cuff on bare arm whenever possible (clothing can muffle sounds and add resistance) |
Avoid errors with correct cuff size and placement, a few minutes of rest, no recent exercise or caffeine, feet flat, and no talking. A full bladder can add 10–15 mmHg, so have the patient use the restroom first. Small technique issues can falsely diagnose hypertension or miss a truly high BP. If a result is unusual, consider what could have skewed it and recheck under better conditions.
Lifespan Considerations
Infants (Birth to 1 year)
Routine BP is not usually done on healthy infants under 3 without indication. Use a small cuff and pediatric stethoscope; place the cuff closer to the elbow due to short arm length. Use palpation or Doppler if auscultation is too hard. Arm and thigh pressures are equivalent in children <1 year. A newborn's systolic BP averages around 70 mmHg at birth and rises in the first month. Soothe the baby first, since crying transiently raises BP.
Children (Toddler to Adolescence)
Begin routine BP checks at age 3, or younger with risk factors. The bladder width should be ~40% of the upper arm circumference. Explain simply ("I'm giving your arm a little hug"). Use palpation or an electronic device under about age 3. Korotkoff sounds can be heard down to 0 mmHg in some children, so Phase 4 muffling is often taken as diastolic. A rough rule of thumb for normal systolic is ~90 + (2 × age in years) for ages 1–7, and ~83 + (2 × age) for ages 8–18; always compare to pediatric percentile charts. Arm vs. thigh BP may differ by about 10 mmHg (thigh higher) after infancy.
Older Adults
Arteries stiffen (higher systolic) and baroreceptor sensitivity decreases (orthostatic hypotension risk). Do not over-inflate the cuff on fragile skin. Use forearm, wrist, or palpation if the arm cannot be positioned. Ask when antihypertensives were last taken. Check BP lying, sitting, and standing if dizziness is reported, and assist with position changes to prevent falls.
Normal Aging vs. Disease
Targets may be slightly higher for older adults, but generally aim for < 130/80 in most hypertensive older patients unless side effects necessitate a higher target. Individualize, since aggressive lowering can cause side effects in fragile patients.
Clinical Alerts and Best Practices
- Do not use a restricted limb. Avoid an arm with an IV infusion or transfusion, an AV fistula, or on the side of a mastectomy or lymph node dissection (lymphedema risk), or an injured or casted arm. Use the other arm or a thigh.
- Observe for orthostatic hypotension in dizzy or fall-risk patients; have them change position slowly with assistance.
- Ensure a quiet environment; talking can raise systolic by ~10 mmHg.
- Patient comfort and timing. Pain, anxiety, recent smoking, or caffeine raise BP. Ideally measure after 5 minutes of rest, with no smoking or caffeine for 30 minutes.
- Multiple readings. Recheck a high reading after a few minutes and consider the other arm; a difference up to ~5-10 mmHg between arms can be normal, larger differences may indicate stenosis. Average two readings 1-2 minutes apart for diagnosis.
- Equipment check. Ensure the aneroid manometer rests at zero when deflated; keep mercury devices maintained and upright; ensure electronic devices are charged and validated.
- Don't overinflate excessively, which causes pain and petechiae and can damage the brachial artery.
- Cleaning and hygiene. Wipe the cuff and clean stethoscope parts between patients.
- Documentation and reporting. Record the reading, date, time, position, and site. Alert the provider for significantly high (systolic >180 or diastolic >120, hypertensive crisis) or symptomatic low readings, in context with the patient's condition.
- Special situations. Use the forearm or lower leg with appropriate cuffs if standard arm measurement is impossible; forearm systolic can run ~5-10 mmHg higher.
- Patient education on cuff placement, resting, and not talking for home monitoring.
- Clinical alerts. A systolic <90 with mental status changes, chest pain, or other symptoms could be shock, act promptly. A BP >180/120 with severe headache, vision changes, confusion, or shortness of breath could be a hypertensive emergency, call the provider immediately.
Frequently Asked Questions
What is a normal blood pressure? The American Heart Association defines normal BP as systolic below 120 mmHg and diastolic below 80 mmHg, written as 120/80 mmHg (AHA). Elevated is 120 to 129 systolic with diastolic under 80, Stage 1 hypertension is 130 to 139 or 80 to 89, and Stage 2 is 140 or higher or 90 or higher (2017 ACC/AHA).
What is the difference between systolic and diastolic pressure? Systolic is the higher number, the pressure when the ventricles contract and push blood out. Diastolic is the lower number, the pressure when the ventricles rest and fill between beats. Both are reported in mmHg as systolic over diastolic.
Why is cuff size so important? An incorrectly sized cuff is one of the most common sources of error. A cuff that is too small or too narrow reads falsely high, and one that is too large reads falsely low. The bladder width should be about 40% of the arm circumference and the length about 80%.
How do you calculate mean arterial pressure (MAP)? MAP = (systolic + 2 × diastolic) / 3. For a BP of 120/80, MAP is about 93 mmHg. The normal range is 70 to 100 mmHg, and a MAP below 70 suggests inadequate organ perfusion.
What is orthostatic hypotension? A drop of at least 20 mmHg systolic or 10 mmHg diastolic within three minutes of standing, usually with dizziness or lightheadedness. Check it by measuring BP and heart rate lying, then sitting or standing, and assist the patient with slow position changes to prevent falls.
Which arm should you avoid for a blood pressure reading? Avoid an arm with an IV or transfusion running, an AV fistula, an injury or cast, or the side of a mastectomy or lymph node dissection because of lymphedema risk. Use the other arm or a thigh with an appropriately sized cuff.
How many readings confirm a hypertension diagnosis? Diagnosis is based on measurements taken on at least two separate occasions, ideally on different days, per the 2017 ACC/AHA guideline. A single high reading should be rechecked under good conditions before drawing conclusions.