PSY4311L, Unit 4 - Blood Pressure Measurement

stethoscope parts

eartips, binaural, binaural spring, PVC tubing, drum (bell and diaphragm, chestpiec and ring)

diaphragm

used for high frequency sounds, commonly used in blood pressure measurement, must apply pressure

bell

used for low frequency sounds, such as other sounds in the heart for diagnosis, only the ring must come in contact

sphygmomanometer parts

artery alignment mark, pressure gauge, cuff with bladders, pressure control valve, bulb, tubes

artery alignment mark

aligns the device to the patient’s brachial artery

pressure gauge

measures the patients blood pressure (mm/Hg), must point to 0 when not used

pressure control valve

closes and opens the device to release or lock in air

bulb

exerts air to the tube to inflate the apparatus

types of sphygmomanometer

mercury, aneroid (two most common), electronic, hybrid (electronic and ambulatory)

mercury sphygmomanometer

most reliable, principle: rise of mercury by applying pressure measures blood pressure of patient

aneroid sphygmomanometer

accessible but easily gets old, principle: tension of the coiled spring is standardized by companies to measure blood pressure

size of blood pressure cuff

checking this is the first step to consider see if the device is appropriate to use for the patient

important questions to interview patient before conducting bp measurement

good sleep, caffeine or alcoholic beverages, feels tired or recently exercised, conditions that will contra-indicate measurement, such as AV-fistula or lymphedema

position of cuff arm

arm at heart level, lower border of cuff 2.5 cm above the antecubital crease, secure, and slightly flex

brachial artery

must be located along the volar crease towards the edge of biceps brachii before placing and securing the bp cuff, where the stethoscope diaphragm is placed during auscultatory blood pressure

palpatory blood pressure measurement

first procedure, will determine how much pressure should be pumped in the cuff bladder during auscultatory blood pressure measurement

radial pulse

pulse along the anterior wrist that must be detected before palpatory blood pressure measurement

15 to 20 mmHg

much pressure must be added once radial pulse disappears during palpatory bp measurement, before valve is released

palpatory blood pressure

while releasing air from the valve, the value on the gauge when the radial pulse must be noted as this score, estimates the systolic pressure

Korotkoff sounds

sounds from stethoscope when measuring blood pressure, caused by turbulent blood flow in the brachial artery as the cuff pressure is released, determines systolic and diastolic blood pressure

systole

first Korotkoff sound heard, force of the blood flow when blood is pumped out of the heart

diastole

last Korotkoff sound heard, measured between heartbeats when the heart is filling with blood; pressure when the heart rests between beats

phase I (Korotkoff sounds)

first appearance of clear tapping sounds, represents systolic blood pressure (SBP), the pressure when the heart contracts

phase II (Korotkoff sounds)

sounds become softer and longer (murmur or swishing sound)

phase III (Korotkoff sounds)

sounds become crisper and louder

phase IV (Korotkoff sounds)

sounds become muffled and softer

phase V (Korotkoff sounds)

sounds disappear completely, represents diastolic blood pressure (DBP), the pressure when the heart relaxes

sources of error in blood pressure measurement

(1) improper positioning of the extremity; (2) improper deflation of the compression cuff; (3) recording the first blood pressure measurement; (4) improper application of the cuff

improper positioning of the extremity

whatever the position of the subject, the position of the artery must be at the level of the heart

improper deflation of the compression cuff

pressure in the cuff should be lowered at about 2 mmHg per heartbeat; if slower, venous congestion will develop = too high diastolic reading; if faster, manometer may fall between 5 or 10 mmHg = too low diastolic reading

recording the first blood pressure measurement

spasm of the artery upon initial comprehension and anxiety and apprehension of the subject can cause reading to be too high; make three measurements, third value is most basal

improper application of the cuff

if rubber bladder bulges beyond covering, high pressure is needed to compress the arm; if cuff is applied too loosely, ballooning of the bladder creates a narrow cuff, both result in excessively high readings

defective aneroid sphygmomanometer

defective air release valve or porous rubber tubing make it difficult to control inflation and deflation of the cuff; gauge tube should be clean, accuracy must be checked regularly (re-calibration), needle should be at zero when deflated

defective mercury sphygmomanometer

check for leaks of mercury liquid in the chamber, air in the rubber tubing or control valve, cracks on the graduated cylinder, or smudges of mercury

defective electronic sphygmomanometer

check if batteries are drained of power, connector or adapter used is working, digital display is complete and clear when turned on

common carotid artery

at the side of the neck

superficial temporal artery

anterior to the ear

facial artery

clench the teeth, and palpate the pulse just anterior to the masseter muscle (in line with the corner of the mouths)

brachial artery

in the antecubital fossa, at the point where it splits into the radial and ulnar arteries

radial artery

at the lateral aspect of the wrist just above the thumb

femoral artery

the crease where your thigh meets your abdomen; in the groin

popliteal artery

bending your knee at a 90-degree angle, pulse behind the knee in the hollow behind the kneecap

posterior tibial artery

just above the medial mallelolus

dorsalis pedis artery

on the dorsum of the foot