BIOELECTRONICS 1 Lec10: ch4 Blood Measurements By 6 October University Faculty of Applied Medical Sciences Department of Biomedical equipment and systems Lec10: ch4 Blood Measurements   By Dr. Eng. Hani Kasban Mahmoud 2017 BIOELECTRONICS 1

JNC VII classification BP classification SBP (mmHg) DBP (mmHg) Normal < 120 And < 80 Prehypertension 120 – 139 Or 80-89 Stage 1 Hypertension 140 – 159 Or 90 – 99 Stage 2 >= 160 Or >= 100 Hypertension diagnosis: Confirm the diagnosis by Checking BP on separate visits.

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.

Devices: Aneroid. Mercury. Electronic.

Blood Pressure measurement Devices Features: 1- Ease of use. Electronic > Aneroid > Mercury 2- Cost. Electronic > Mercury > Aneroid 3- Accuracy. Mercury > Aneroid > Electronic 4- Memory. Electronic only.

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.

Factors that affect BP measurement Smoking. Caffeine. Cuff size. Pain. Medication use.

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.

Measurement of BP in the clinic patient must be seated in a chair with arm support on both sides. The setting should be quiet and relaxed. It must be easy to adjust the height of the arm so that the middle of the cuff is at heart level (at the 4th intercostal space). From www.images.md

Selecting the most accurate blood pressure cuff The width of the cuff bladder should encircle at least 40% of the arm, and the length of the bladder must encircle at least 80% of the arm. Most cuffs in use are not marked correctly. From www.images.md

Selecting the most accurate blood pressure cuff From www.images.md

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.

Where to listen for blood pressure sounds 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. Palpate the brachial artery just medial to and usually under the biceps tendon in the antecubital fossa. Place the bell of the stethoscope directly over this pulse to get the best Korotkoff (K) sounds. From www.images.md

Determining the palpated systolic pressure and the maximum inflation level 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. Figure 15-11. Determining the palpated systolic pressure and the maximum inflation level (MIL). The reason for estimating the palpated systolic pressure and the MIL is to assure that an auscultatory gap does not give the observer a wrong reading. After a rest period of at least 5 minutes, find the MIL. Palpate the radial artery at the wrist (A). Use this pulse to determine when the pressure in the cuff has exceeded the systolic pressure. Then determine the MIL as described in B. From www.images.md

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

Measurement of BP 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.

Many thanks Dr. Eng. Hani Kasban Questions?????