Non invasive blood pressure

1, Overview Blood pressure BP is the pressure exerted by circulating blood upon the walls of blood vessels  When used without further specification, "blood pressure" usually refers to

Non-invasive Blood Pressure

 1, Overview

 2, Physiological basis

 3, Methods to measure blood

 4, NIBP system

 5, Auscultatoru Method (KOROTKOFF sound method)

 6, Oscillometric

1, Overview

 Blood pressure (BP) is the pressure exerted by circulating blood upon the walls of blood vessels

 When used without further specification, "blood pressure" usually refers to the arterial pressure in the systemic circulation It is usually measured at a person's upper arm

 Blood pressure is usually expressed in terms of the systolic (maximum) pressure over diastolic (minimum) pressure and is measured in millimeters of mercury (mm Hg)

 It is one of the vital signs along with respiratory rate, heart rate, oxygen saturation, and body temperature Normal resting blood pressure in an adult is approximately 120/80 mm Hg

1, Overview

 Blood pressure varies depending on situation, activity, and disease states It is regulated by the nervous and endocrine systems

 Blood pressure that is low due to a disease state is called hypotension (<80mmHg), and pressure that is consistently high is hypertension (>140mmHg) Both have many causes which can range from mild to severe Both may be of sudden onset or of long duration

 Long term hypertension is a risk factor for many diseases, including kidney failure, heart disease, and stroke Long term hypertension often goes undetected because of infrequent monitoring and the

absence of symptoms

2, Physiological basis

 Systolic Blood Pressure: It is specifically the maximum arterial

pressure during contraction of Heart

 Diastolic Blood Pressure: Diastolic pressure, refers to the lowest pressure within the arterial blood stream due to expandion of heart

 Normal human heart beat about 75 beats / min, while one cycle

cardiac last 0.8s been divided into phases:

Atrial mustered 0.1s; pressure from 2 to 3 mmHg -> atrium valve extended -> blood from atria to the ventricles

Ventricle mustered 0.33s; consists of two phases: increase the pressure: 0.08s and ejection blood stage: 0.25s, 60 – 70 ml blood each time

Diastolic : 0,37 s ; consists 3 phases: pre - diastolic: 0,04s is the intermediate stage between the diastolic and systolic, dilated cardiomyopathy : 0,08s; full blood: 0,25s In this phases, blood from atrial to ventricle, this time the heart is rested prepare for the next cycle

2, Physiological basis

So, each time the heart pumps blood, it also creates a pressure wave propagating in the aorta travels through the body Base on this, can indirectly measure the pressure relative ejection of the heart through the blood pressure measured typically in the aorta at hand

Maximum blood pressure: systolic blood pressure: is determined at the time the curve shows change arterial pressure suddenly increased dramatically it shows the smooth

muscle contractility and heart rate Human normal have blood pressure maximum value from 100 to 110 mmHg Common ranges are 90 to 140 mmHg

Minimum blood pressure: diastolic blood pressure is determined at the time the curve shows the change arterial pressure is decreased suddenly switched to decrease slowly Its expression of vascular resistance: typically in the range from 50 mmHg to 90 mmHg

The average blood pressure: blood pressure of regulations (effective) exist throughout the systolic and diastolic created a proper blood flow by the maximum blood pressure and minimum triggers Is determined at the time of arterial blood pressure with the

greatest amplitude and blood pressure don't increse, but it began to decline Usually by 90mmHg

2, Physiological basis

3, Methods to measure blood

There are 3 basic ways to measure the blood :

1. Auscultatory

2. Oscillometric

3. Direct method

 2 ways first is non invasive blood pressure and last way is invasive blood pressure.

4, Auscultatoru Method (Korotoff sound method)

 The auscultatory method (from the Latin word for “listening”) uses a stethoscope and a sphygmomanometer

 This comprises an inflatable (Riva-Rocci) cuff placed around the upper arm at roughly the same vertical height

as the heart, attached to a mercury or aneroid manometer

 A cuff of appropriate size is fitted smoothly and also snugly, then inflated manually by repeatedly squeezing a

rubber bulb until the artery is completely occluded It is important that the cuff size is correct: undersized cuffs record too high a pressure; oversized cuffs may yield too low a pressure Usually three or four cuff sizes should

be available to allow measurements in arms of different size

4, Auscultatoru Method (Korotoff sound method )

 Listening with the stethoscope to the brachial artery at the antecubital area of the elbow, the examiner slowly releases the pressure in the cuff When blood just starts to flow in the artery, the turbulent flow creates a "whooshing" or pounding (first Korotkoff sound) The pressure at which this sound is first heard

is the systolic blood pressure The cuff pressure is further released until no sound can be heard (fifth Korotkoff sound), at the diastolic arterial pressure

 The auscultatory method is the predominant method of clinical measurement.

4, Auscultatoru Method (Korotoff sound method)

5, Oscillometric

 The oscillometric method involves the observation of oscillations in the

sphygmomanometer cuff pressure which are caused by the oscillations of blood flow

 It uses a sphygmomanometer cuff, like the auscultatory method, but with an electronic pressure sensor (transducer) to observe cuff pressure oscillations, electronics to

automatically interpret them, and automatic inflation and deflation of the cuff The pressure sensor should be calibrated periodically to maintain accuracy

5, Oscillometric

 The cuff is inflated to a pressure initially in excess of the systolic arterial pressure and then reduced to below diastolic pressure over a period of about 30 seconds When blood flow is nil (cuff pressure exceeding

systolic pressure) or unimpeded (cuff pressure below diastolic pressure), cuff pressure will be essentially constant When blood flow is present, but restricted, the cuff pressure, which is monitored by the pressure sensor, will vary periodically in synchrony with the cyclic expansion and

contraction of the brachial artery, it will oscillate

 Over the deflation period, the recorded pressure waveform forms a signal known as the cuff deflation curve A bandpass filter is utilized to extract the oscillometric pulses from the cuff deflation curve

5, Oscillometric

 Over the deflation period, the extracted oscillometric pulses form a signal known as the oscillometric waveform (OMW) The amplitude

of the oscillometric pulses increases to a maximum and then

decreases with further deflation A variety of analysis algorithms can

be employed in order to estimate the systolic, diastolic, and mean arterial pressure

 In practice the different methods do not give identical results; an

algorithm and experimentally obtained coefficients are used to adjust the oscillometric results to give readings which match the

auscultatory results as well as possible Some equipment uses

computer-aided analysis of the instantaneous arterial pressure

waveform to determine the systolic, mean, and diastolic points.

 The term NIBP, for non-invasive blood pressure, is often used to

describe oscillometric monitoring equipment

5, Oscillometric