Diagnostic Devices: Part Two : Biomedical Lecture Notes PDF

Lecture 7 (9/26/2024) Diagnostic Devices: Part Two Introduction to Biomedical Engineering Technology Euiheon Chung [email protected] , X 2735 Department of BioMedical Science and Engineering Gwangju Institute of Sciences and Technology Copyright. Most figures/tables/texts in this le...

Lecture 7 (9/26/2024) Diagnostic Devices: Part Two Introduction to Biomedical Engineering Technology Euiheon Chung [email protected] , X 2735 Department of BioMedical Science and Engineering Gwangju Institute of Sciences and Technology Copyright. Most figures/tables/texts in this lecture are from the textbook “Introduction to Biomedical Engineering Technology by Laurence Street 2016” and this material is only for those who take this class and cannot be distributed to anyone without the permission from the lecturer.  Objectives ✓ To examine the circulatory system including the characteristics of blood: blood pressure, blood oxygen, blood gases, and blood flow 2  Design of the Vascular System Saltzman, Biomedical Engineering, 2nd Ed, Fig. 8.7 3  Circulatory System and Blood Pressure Blood pressure (BP, 혈압): most commonly measured vital sign, a physical parameter – the pressure exerted by blood on the vessel walls of the circulatory system – Note: pressure measurements vary over time and locations in the system – BP in general is modified by various normal and abnormal physiological conditions From cyclic pumping of the heart, BP varies correspondingly, with highest value at the point of maximal cardiac output, falling to a low value between contractions. – Systolic BP 수축기 혈압: the maximum arterial pressure during contraction of the heart – Diastolic BP 확장기 혈압: the lowest pressure within the arterial blood stream due to the expansion of the heart – Mean arterial pressure (MAP): an average blood pressure in an individual during a single cardiac cycle * Cardiac output: the volume of blood being pumped by the heart per unit time (5~ 6 L/min) 4  Blood Pressure Reading & Age REF ONLY Representation of the arterial pressure waveform over one cardiac cycle. Unit: mmHg https://www.bcm.edu/bodycomplab/Flashapps/BPVAgeChartpage.html 5 Main Complications of Persistent High Blood Pressure wikipedia.org 6  Hypertension/Hypotension Normal BP: Systolic BP < 120, Diastolic BP < 80 mm Hg Hypertension (고혈압): increased blood pressure, SBP/DBP >140/90 – Cause: renal system problem, abnormal responses of the autonomic nervous system – Note: persistent hypertension can cause strokes 뇌졸중, *aneurisms 동맥류 , kidney failure and other cardiovascular disease including atherosclerosis (죽상경화증, 아테로마성 동맥 경화증) Hypotension (저혈압): abnormally low blood pressure, < 65 mm Hg – Cause: faulty autonomous nervous system or blood loss, severe infections, toxins, hormonal imbalances – Reduced perfusion 관류(灌流) of all organs, most significantly to the brain – understood as a physiological state, rather than a disease – Note: Reduced cognitive function, dizziness, unconsciousness, and eventually death can result * Aneurism: an excessive localized enlargement of an artery caused by a weakening of the artery wall. 7 The Effects of High Blood Pressure REF ONLY * Atheromatous plaque, plaque: an abnormal accumulation of materials in the inner layer of an arterial wall Atherosclerotic wikipedia.org 8  Carotid Arteries and Plaque REF ONLY 경(頸)동맥(의) https://vascular.surgery.ucsf.edu/conditions--procedures/carotid-ultrasound.aspx 9  Atherosclerosis and Plaque REF ONLY Cause: prolonged periods of hypertension or by excess amounts of cholesterol in the blood Effect on heart: reduction in cardiac perfusion produce ‘angina (chest pain, 협심증)’ and heart attack https://opentextbc.ca/anatomyandphysiology/chapter/20-2-blood- ow-blood-pressure-and-resistance/10 fl Arteriosclerosis vs. Atherosclerosis Arteriosclerosis (동맥경화증) – the hardening, stiffening, and loss of elasticity of the walls of arteries – This process gradually restricts the blood flow to one's organs and tissues and can lead to severe health risks brought on by atherosclerosis Atherosclerosis (아테로마성 동맥경화증) – a specific form of arteriosclerosis – the narrowing of artery due to the plaque buildup sticky deposit – plaque: a small, distinct, typically raised patch or region resulting from local damage or deposition of material, such as a fatty deposit on an artery wall 11 History: The First BP Measurements Invasive BP measurement – Stephen Hales (1733) – Intra-arterial BP of a horse body inserting a glass tubes directly Non-invasive BP measurement – N.C. Korotkoff (1905) – Auscultation of brachial artery, still widely used today 12  Blood Pressure Value BP value depends on two main factors: 1. Cardiac output (Blood volume): the more blood volume in the body, the higher the rate of blood return to the heart and the resulting cardiac output, potentially resulting in higher arterial pressure 2. Resistance of blood flow: the higher the resistance, the higher the arterial pressure resistance depends on vessel diameter, blood viscosity, smoothness of the blood vessel wall 13 BP Measurement: Invasive vs. Non-invasive Two main categories of BP measurement w.r.t. the invasiveness of a medical measurement Non-invasive: not requiring entering or penetrating the body or disturbing body tissue Invasive: requiring the entry of a needle, catheter 카테터 , or other instrument into a part of the body * catheter is a soft hollow tube 14  BP Measurement Site brachial radial Brachial artery상완 동맥 is the most common measurement site: – Close to the heart and convenient for measuring http://accuratebloodpressure.com/blood_pressure.html 15 * sphygmo-: from Greek sphugmos ‘pulse.’ * stethoscope: from Greek stēthos ‘breast’ + skopein ‘look at.’ sphygmomanometer 혈압계, 맥압계 stethoscope 청진기 16  Auscultatory Method (non-invasive) Palpatory method (ancient China) Auscultation (청진): – The act of ‘listening’, either directly or through a stethoscope or other instruments, to sounds within the body – Based on the pulse waves when first propagate through the brachial artery, generate Korotkoff sounds http://healthy-ojas.com/systems/tcm-diagnosis.html http://slideplayer.com/slide/4492154/ 17 Auscultatory Method: Korotkoff sounds Korotkoff sounds: – pulse wave from the brachial artery can be heard when the external pressure below systolic or above diastolic. + still in common use, inexpensive and simple - requires human attention, time-consuming, variation can result from medical staff (Note: not for infants) http://211.70.128.25/2005/shenglx/syjx/shyjy/Experiment%201.html 18  Oscillometric Method (non-invasive) www.anesthesiology.com 19 https://www.amazon.com/Omron-HEM-711AC-Automatic-Pressure-Standard/dp/B00006WNPW  Oscillometric Method Oscillometric method – based on the oscillations of blood flow during the pulsation – Using a sphygmomanometer cuff, like the auscultatory method, but with pressure sensor (transducer) to observe cuff pressure oscillations Pressure sensor within the inflated cuff: – detects the pulsation of the artery wall as a pressure vibration; the amplitude provides the BP value Pros and cons of Oscillometric method + simple and reliable + can be used with the case of hypotension and infant - motion artifact Used for most automated NIBP (non-invasive BP) devices 20  Nomenclature Review encephalopathy 뇌증 Hypertension (고혈압) retinopathy 망막 병증 경련, 경기 Hypotension (저혈압) convulsion cardiomyopathy 심근 병증 Angina (chest pain, 협심증) nephropathy 신 병증 myocardial 심근 경색증 infarction Auscultation (청진) sphygmomanometer 혈압계, 맥압계 stethoscope 청진기 Arteriosclerosis (동맥경화증) Atherosclerosis (아테로마성 동맥경화증) Brachial artery 상완 동맥 21  Blood Carrying Oxygen Blood carries the oxygen to various organs in our body The main way oxygen is carried in our blood is by hemoglobin. Note) Normal oxygen saturation values are 97% to 99% in a healthy individual Ratio of saturation: 22  Pulse Oximeter A device to measure oxygen saturation in the body (i.e. how much of the hemoglobin is carrying the oxygen) Oxygen saturation: the total amount of the saturated form of hemoglobin (oxy hemoglobin) compared to the non-saturated form (deoxy hemoglobin) an indication of the effectiveness of ventilation and gas exchange in the lungs * SpO : Peripheral oxygen saturation 2 C HbO2 SpO2 (%) = × 100 C HbO2 + C Hb Note) Normal oxygen saturation values are 97% to 99% 23  Where to use Pulse Oximeters? Operating room, Emergency room, ICU, Post-anesthesia care Ambulances, Delivery suites, Cardiac catheterization laboratories, and Home * ICU: intensive care unit https://www.design-inspiration.net/inspiration/duo-li-finger-pulse-oximeter/ https://www.thisiswhyimbroke.com/baby-vital-signs-monitor/ 24  Principle of Pulse Oximetry Light sources: 650 nm and 805 nm LED 25 http://readingrat.net/block-diagram-of-pulse-oximeter/improve-sensor-performance-and-snr-in-pulse-oximeter-designs/ Issues that Interfere with Pulse Oximetry Nail polishes CO binding to hemoglobin Toxins or disease conditions can alter normal hemoglobin, producing methemoglobin Low perfusion reduces the accuracy of the measurements High levels of ambient light can affect readings  BLOOD CHEMISTRY ANALYZERS Blood chemistry test: to assess many conditions and learn how the body’s organs are working Blood test: check electrolytes, minerals, and other chemicals including glucose, etc. Chemistry analyzers: benchtop device or placed on a cart to determine the concentration of certain metabolites, electrolytes, proteins, and/or drugs in samples of serum, plasma, urine, cerebrospinal fluid (CSF), and/or other body fluids  POC Blood Analysis POCT (point-of-care testing) smaller samples of blood are required the results are obtained more quickly tests designed to be used at or near the site where the patient is located, that are performed outside the physical facilities of the clinical laboratories. Several drops of blood Insert the cartridge View the results Upload information https://www.pointofcare.abbott/int/en/offerings/istat/istat-handheld Glucometer Kits: Conventional & Modern https://www.amazon.com/dp/B00N4T3CRM?psc=1#customerReviews http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ac504300n#fig1  GLUCOMETERS Glucometer: a medical device for determining the approximate concentration of glucose in the blood Noninvasive glucometers: clinically or commercially viable product are emerging Continuous glucose monitors: a disposable sensor placed under the skin, a transmitter connected to their sensor and a reader that receives and displays the measurements + real-time measurements, reduce the need for finger prick testing - not as accurate as the reading is in the interstitial fluid which lags behind the levels in the blood https://www.youtube.com/watch?v=5Patm9FEdv4 DOI : https://doi.org/10.1021/acs.nanolett.1c01880  Components of Glucometer Kit Lancet: use to puncture the skin Test strips: onto which a droplet of blood is placed and inserted into the reader Calibration strip for each batch of test strips: for internal calibration Strip reader: measure and display of blood glucose level http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ac504300n#fig1  Continuous Glucose Monitor REF ONLY https://www.ontrackdiabetes.com/type-1-diabetes/what-continuous-glucose-monitor-cgm 32 Blood glucose levels: mg/dL or mmol/L Normal blood glucose levels can fluctuate, and fasting blood glucose levels are being measured Normal: < 110 mg/dL, Diabetic: > 126 mg/dL Hypoglycemia 저혈당증 symptoms: unsteadiness, perspiration, dizziness, rapid heart rate, confusion insulin shock ( < 50 mg/dL) Hyperglycemia 고혈당증 symptoms: ( > 180 mg/dL) excess thirst, headache, blurred vision, fatigue Chronic hyperglycemia: impaired nerve function in the lower legs and feet decreased healing ability vision problems, stomach and intestinal malfunctions Carotid Ultrasound for Blood Flow Doppler Effect for Flow Measurements REF ONLY Doppler effect: the change in frequency or wavelength of a wave for an observer who is moving relative to the wave source. http://www.mathpages.com/rr/s2-04/2-04.htm  Ultrasonic Flow Meter a type of flow meter that measures the velocity of a fluid with ultrasound to calculate volume flow Principle: Ultrasonic flow meters measure the difference of the transit time of ultrasonic pulses propagating in and against flow direction. This time difference is a measure for the average velocity of the fluid along the path of the ultrasonic beam. Wikipedia http://demo.webassign.net/ebooks/cj6demo/pc/c16/read/main/c16x16_10.htm  Summary Circulatory System and Blood Pressure PULSE OXIMETERS TRANSCUTANEOUS CO2 ANALYZERS BLOOD CHEMISTRY ANALYZERS GLUCOMETERS DOPPLER BLOOD FLOW DETECTORS 37