Measuring blood pressure

&pulse rate

All arteries carry blood away from the heartAll veins carry blood to the heartMost arteries carry oxygenated bloodMost veins carry de-oxygenated blood

Veins have valves that prevent blood from flowing in the wrong direction

Veins are wider than arteries

Contraction of body muscles helps the blood flow through the veins

Arteries have more elastic tissue and a thick muscular layer to cope with the high pressure of blood flow caused by the heart beat

Capillaries transport blood from the arterioles to venules.

They are microscopic vessels which are in most of our organs.

They are one cell thick so they allow exchange of gas (O2;CO2); salts and water to occur between the capillaries and surrounding tissue.

The pulse may be palpated at any place that allows an artery to be compressed against a bone.

Pressure waves generated by the heart in systole moves against the arterial wall.

The pulse can be used as a tactile guide to determine the systolic blood pressure (diastolic not palpable).

The pulse pattern can be clinically significant, so it is important to note;1. The rate in beats per minute.2. The rhythm of pulse.

• Fast• Slow• irregular

3. The strength of the pulse.1. Absent2. Barely palpable3. Easily palpable4. Full5. bounding

Your pulse varies depending on your age, level of fitness and how active you are being.A resting pulse is used in practice to record rate.The pulse rate needs to be taken over 1 full minute.

The normal heart beat

Terminology

Slow pulse rate <60b/min = bradycardia Fast pulse rate >100b/min (resting) =

tachycardia Irregular pulse – related to palpitations

All these need to be referred to a healthcare professional as they indicate an underlying problem – ask the patient

if they are aware of any problemsWhen you document the rate also document the rhythm

(e.g.regular or irregular)

What else can affect the heart rate?

Caffeine & alcohol – increases the strength and frequency of the heartbeat therefore increasing the rate

Exercise increases the heart rate, but someone who exercises regularly may have a low resting rate.

Disease affect the heart rate. Thyroid disease can either make the rate faster or slower depending type of disease.

Drugs (medical & recreational) e.g. digoxin & bets blockers slow the HR. Recreational drugs tend to increase HR.

• Count the heart beats for 60 seconds

• It needs to be a resting pulse rate

• Remember to check rate, rhythm & strength

1. Temporal

2. External maxillary (facial)

3. Carotid

4. Brachial

5. Radial

6. Femoral

7. Popliteal

8. Posterior tibial

9. Dorsal pedis

Blood Pressure

What is blood pressure?

Blood pressure refers to the force exerted by

circulating blood on the walls of blood vessels. The pressure of the circulating blood decreases

as blood moves through arteries, arterioles,

capillaries, and veins. Blood pressure values are reported in

millimetres of mercury (mmHg). Blood pressure is recorded as systolic over

diastolic e.g. 120/60.

What is blood pressure? (tap & hose)

Short term control – ANS – barareceptors – vagus nerve.

Intermediate control - Trans-capillary shift – osmosis/plasma proteins.

Long term control – Renin/angiotensin system; aldosterone.

How is blood pressure controlled

RAS System

The systolic arterial pressure is defined as the

peak pressure in the arteries, which occurs near

the beginning of the cardiac cycle. The diastolic arterial pressure is the lowest

pressure (at the resting phase of the cardiac cycle Measures of arterial pressure are not static, but

undergo natural variations from one heartbeat to

another and throughout the day. Blood pressure also changes in response to

stress, nutritional factors, drugs, or disease.

Systole is the contraction of heart chambers, driving blood out of the chambers.The chamber valves are closed.

Diastole is the period of time when the heart fills with blood after systole (contraction).The chamber valves are open. The heart is at rest.

High blood pressure (or hypertension) is defined in an adult as a blood pressure greater than or equal to 140 mm Hg systolic pressure or greater than or equal to 90 mm Hg diastolic pressure.

High blood pressure directly increases the risk of coronary heart disease (which leads to heart attack) and stroke, especially when it's present with other risk factors.

High blood pressure is the most important preventable cause of premature ill-health.

Around 5.7 million people have

hypertension which is undiagnosed. There is no universally accepted

definition of hypotension (low blood

pressure). Chronic disease have a lower target

threshold e.g. diabetes; CKD.

Risk factors for developing hypertensionObesity Physical inactivityHigh consumption of alcoholHigh intake of dietary sodiumLow intake of dietary potassium StressIncreasing age Cigarette smoking Increased blood cholesterolPatients with systemic diseases including: Diabetes

mellitus; renal disease; peripheral vascular diseaseFamily history of hypertension, CHD or stroke

Measuring blood pressureNICE clinical guideline 127; Quick reference guide; Aug 2011

HCP need adequate training and should have their performance reviewed periodically

Devices for measuring BP must be properly validated, maintained and regularly recalibrated according to manufacturers instruction

Ensure an appropriate cuff size for the patient’s arm is used

Standardize the environment; relaxed temperate setting with the person quiet and seated with arm outstretched and supported

Palpate the radial or brachial pulse before measuring BP

Blood Pressure MeasurementWith Electronic Blood Pressure Monitors

Points to note;

If checking an electronic device against a mercury or aneroid sphygmomanometer the blood pressure may differ slightly between devices.

It is good practice to occasionally check the monitor against a aneroid sphygmomanometer or another validated device.

It is important to have a monitor calibrated according to manufacturer’s instruction.

These devices should not be used for people with an irregular heart beat (Atrial Fibrilation) or heart rate lower than 50 beat/min

Blood pressure measurement Estimation of blood pressure by auscultation(NICE clinical Guideline 34 Partial update of CG 18)

Standardise the environment as much as possible: − relaxed temperate setting, with the patient seated − arm out-stretched, in line with mid-sternum, and supported.

Correctly wrap a cuff containing an appropriately sized bladder around the upper arm and connect to a manometer. Cuffs should be marked to indicate the range of permissible arm circumferences; these marks should be easily seen when the cuff is being applied to an arm.

Palpate the brachial pulse in the antecubital fossa of that arm. Rapidly inflate the cuff to 20 mmHg above the point where the

brachial pulse disappears. Deflate the cuff and note the pressure at which the pulse re-

appears: the approximate systolic pressure. Re-inflate the cuff to 20 mmHg above the point at which the brachial

pulse disappears.

Using one hand, place the stethoscope over the brachial artery ensuring complete skin contact with no clothing in between.

Slowly deflate the cuff at 2–3 mmHg per second listening for Korotkoff sounds.

Phase I: clear tapping sound (SBP) Phase II: Auscultatory gap: swishing sound or soft murmur Phase III: Loud slapping sound Phase IV: sudden muffling of sound Phase V: disappearance of sound (DBP)

The first appearance of faint repetitive clear tapping sounds gradually increasing in intensity and lasting for at least two consecutive beats: note the systolic pressure.

A brief period may follow when the sounds soften or ‘swish’. In some patients, the sounds may disappear altogether.

The return of sharper sounds becoming crisper for a short time. The distinct, abrupt muffling of sounds, becoming soft and blowing in quality. The point at which all sounds disappear completely: note the diastolic

pressure. When the sounds have disappeared, quickly deflate the cuff completely if

repeating the measurement. When possible, take readings at the beginning and end of consultations.

Terminology

high blood pressure = hypertension

low blood pressure = hypotension

fast pulse rate = tachycardia

slow pulse rate = bradycardia

Pediatrics. 2012 May;129(5):e1205-e1210. Epub 2012 Apr 16.

Comparison of Mercury and Aneroid Blood Pressure Measurements in Youth.

Shah AS, Dolan LM, D'Agostino RB Jr, Standiford D, Davis C, Testaverde L, Pihoker C, Daniels SR, Urbina EM; for the SEARCH for Diabetes in Youth Study Group.

SourceDivision of Endocrinology, ML 7012, Cincinnati Children's Hospital, 3333 Burnet Ave, Cincinnati, OH 45229.

amy.shah@cchmc.org.AbstractOBJECTIVE: Because of concerns about the safety and environmental impact of mercury, aneroid sphygmomanometers have replaced

mercury-filled devices for blood pressure (BP) measurements. Despite this change, few studies have compared BP measurements between the 2 devices.

METHODS: The SEARCH for Diabetes in Youth Study conducted a comparison of aneroid and mercury devices among 193 youth with

diabetes (48% boys, aged 12.9 ± 3.7 years; 89% type 1). Statistical analyses included estimating Pearson correlation coefficients, Bland-Altman plots, paired t tests, and fitting regression models, both overall and stratified by age (<10 vs ≥10-18 years).

RESULTS: Mean mercury and aneroid systolic and diastolic BPs were highly correlated. For the entire group, there was no significant

difference in mean systolic BP using the aneroid device, but there was a -1.53 ± 5.06 mm Hg difference in mean diastolic BP. When stratified by age, a lower diastolic BP (-1.78 ± 5.2 mm Hg) was seen in those ≥10 to 18 years using the aneroid device. No differences in systolic BP were observed, and there were no differences in BP by device in individuals <10 years. Regression analyses did not identify any explanatory variables.

CONCLUSIONS: Although a small discrepancy between diastolic BP measurements from aneroid

versus mercury devices exists, this variation is unlikely to be clinically significant, suggesting that either device could be used in research or clinical settings.