Blood Pressure Measurement

physiology

1. BLOOD PRESSURE MEASUREMENT

2. Diseases Attributable to Hypertension © Continuing Medical Implementation ….. .bridging the care gap Hypertension Heart failure Stroke Coronary heart disease Myocardial infarction Left ventricular hypertrophy Aortic aneurysm Retinopathy Peripheral vascular disease Hypertensive encephalopathy Chronic kidney failure Cerebral hemorrhage Adapted from: Arch Intern Med 1996; 156:1926-1935 . All Vascular

3. WHAT IS BLOOD PRESSURE? Blood pressure (BP) is a measure of the force that the circulating blood exerts against the arterial wall.

4. SYSTOLIC PRESSURE Systolic pressure is the maximum pressure exerted by the blood against the arterial walls. It results when the ventricles contract ( systole )

5. DIASTOLIC PRESSURE Diastolic Pressure is the lowest pressure in the artery. It result when the ventricles are relaxed (diastole )

6. British Hypertension Society classification of blood pressure levels Blood pressure Systolic BP (mmHg) Diastolic BP (mmHg) <120 <80 Optimal <130 <85 Normal 130-139 85-89 High normal Hypertension 140-159 90-99 Grade 1 (mild) 160-179 100-109 Grade 2 (moderate) >180 >110 Grade 3 (severe) Isolated systolic hypertension 140-159 <90 Grade 1 >160 <90 Grade 2

7. BP is measured in mmHg and recorded as systolic pressure/diastolic pressure, together with where, and how, the reading was taken, e.g. BP: 146/92 mmHg, right arm, supine. BP is an important guide to cardiovascular risk and provides vital information on the haemodynamic condition of acutely ill or injured patients. BP constantly varies and rises with stress, excitement and environment .

8. Blood Pressure measurement Office BP measurement: Two readings, 5 minutes apart, sitting. Ambulatory BP monitoring: For white coat hypertension. Self-measurement of BP: Information on response to therapy, may improve adherence to therapy.

9. Devices: Aneroid. Mercury. Electronic. Devices : Aneroid. Mercury . Electronic .

10. Time of measurement Use multiple readings at different times during the waking hours of the patient. For patient taking antihypertensive medications monitoring of blood pressure should be done before taking the scheduled dose.

11. Patient position BP should be measured in sitting position. Patient should sit for 5 minutes before measuring BP. In elderly, supine and standing position can be used to detect postural hypotension.

12. Selecting the most accurate blood pressure cuff The length of the bladder should be at least 80% of the circumference of the upper arm. The width of the bladder should be approximately 40% of the circumference of the upper arm.

13. Where to listen for blood pressure sounds From www.images.md 1- Locate the antecubital fossa of the patient’s arm and palpate the brachial artery. This location is the point over which the stethoscope is placed to listen for Korotkoff sounds later. 2- Wrap the cuff approximately 2.5 inch above the antecubital fossa.

14. Determining the palpated systolic pressure and the maximum inflation level From www.images.md 3. While palpating the radial pulse, inflate the cuff until you feel the radial pulse disappear. Note the pressure on the manometer at this point and rapidly deflate the cuff.

15. Measurement of BP 4- Place the stethoscope lightly over the brachial artery and inflate the cuff to a pressure 30 mm Hg greater than estimated systolic pressure.         5- Deflate the cuff slowly at a rate of 2 mm Hg per heartbeat. 6- Systolic pressure equal the pulse first heard by auscultation

16. 7- Deflate the cuff until the sounds become muffled and then disappear. The disappearance of sound estimate the diastolic pressure. 8- Record the blood pressure reading in even numbers. Note patient’s position, cuff size, and arm used for measurement.

17. Korotkoff sounds These noises are produced from under the distal half of the BP cuff between systole and diastole because the artery collapses completely and reopens with each heartbeat. As the artery wall rapidly opens it causes a snapping or tapping sound (like the sail of a boat snapping in the wind). As the cuff pressure falls below the diastolic pressure, the sound disappears as the vessel wall no longer collapses but gently expands with each beat. The first appearance of the sound (phase 1) indicates systole. As the pressure is reduced, the sounds muffle (phase 4) and then disappear (phase 5). Inter-observer agreement is better for phase 5 and this is recorded as diastolic BP. Occasionally muffled sounds persist (phase 4) and do not disappear; in this case, record phase 4 as the diastolic pressure.

18. © Continuing Medical Implementation ….. .bridging the care gap

19. Common problems in BP measurement BP different in each arm: A difference >10 mmHg suggests peripheral vascular disease and raises the possibility of renal artery stenosis as the cause of hypertension. Record the highest pressure and treat this Wrong cuff size: A cuff of 12.5 × 23 cm is suitable for only 60% of Europeans. The bladder should encircle between 80% and 100% of the arm. In obese patients with large arms a normal-sized cuff will over-estimate BP and the error is greater when the centre of the cuff is not over the brachial artery. Therefore for obese patients a larger cuff must be used. Using too large a cuff produces only a small under-estimation of BP (2-3 mm in systolic BP)

20. Auscultatory gap: Up to 20% of elderly hypertensive patients have phase 1 Korotkoff sounds which begin at systolic pressure but then disappear for varying lengths of time, reappearing before diastolic pressure. If the first appearance of the sound is missed, the systolic pressure will be recorded at a falsely low level. Avoid this by palpating the systolic pressure first Excess pressure of stethoscope: Excess pressure can artificially lower the diastolic reading by 10 mmHg. The systolic pressure is not usually affected Patient's arm at the wrong level: The patient's elbow should be level with his heart. Hydrostatic pressure effects mean that if the arm is 7 cm higher, both systole and diastole pressures will be 5 mmHg lower. If the arm is 7 cm lower than the heart, they will be about 6 mm higher

21. Postural change: When a healthy person stands, the pulse increases by about 11 bpm and stabilizes after 1 min. The BP stabilizes after 1-2 min. Check the BP after a patient has been standing for 2 min; a drop of ≥20 mmHg on standing is postural hypotension Abnormal pulse pressure: The pulse pressure is the difference between the systolic and diastolic pressures. A pulse pressure of ≥80 mmHg suggests aortic regurgitation, while a low pulse pressure may occur in aortic stenosis.

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