Biomedical Instrumentation (medical pratice) Flashcards
Measurement of body temp
- measurement of elevated body temp is oftent the first sign of a abnormal condition
Mercury thermometer
principle of thermal expansion, rises when hot, drops when cool
Electronic thermometer
use fo thermocouples or thermistors as the sensing unit, sensing element can be placed in direct or contact the body
Ear thermometer
-noncontact probe that senses IR radiaton emitted from the tympanic membrane
-emitted IR is measured witha a pyroceletrical signal
-prone to underestimation
Pyroelectricity
is a property of certain materials
- they respond to heat by the generation of an electrical potential
-natural materials such as quartz and bones exhibit pyroelectric behvior
measurement of blood pressure
provides rapid information about the health of the cardiovascular system
High BP (hypertension)
-heart attack
-atherous derosis
-congestive heart failure
Low BP (hypotension)
cause of lacj of blood and oxygen delievery
What is blood pressure measured as?
systolic / diastolic pressure
Systolic pressure
maximum pressure exerted on the arterial walls during contraction
Diastolic pressure
occurs during relaxation of the ventricles
Normal blood pressure?
High blood pressure?
120/80
140/90
Catherization
-most direct method of measuring blood pressure (invasive, only used when needed)
How does catherization work?
catheter is filled with a fluid which transduces the arterial pressure to an external (or internal) pressure transducer
Catheter
long, thin, flexible tube gets threaded through the circultaroy system to reach places deep in the body
Korotkoff sounds
series of sounds when blood pressure cuff is being inflated and deflated
Auscultatory
refers to listening to the sounds within the body
(most common when measuring blood pressure)
Korotkoff BP measurement
- an air filled cuff is wrapped around the patients arm
- a stethoscope is placed under the cuff and the cuff is inflated to a pressure that exceeds the systolic pressure
- a fully inflated cuff completely stops the blood flow
4, as pressure in the cuff is slowly released, operator listens for noise
What do Dr listen for when recording blood pressure?
-Appearnace of sounds is the start of systole (or the reapperance)
-Disappearance of sounds the start of diastole
Measurement of oxygen saturation
relative measure of the amount of oxygen that id carried (dissolved) in blood
- proper blood O2 + CO2 levels are critcal for maintence of pH and healthy function of cells
Lung diseases that cause low O2 levels in the blood (hypoxemia)
-asthma
-emphysema
-severe pneumonia
-pulmonary edema (fluid in the lungs)
Is blood oxygen monitored for all patients during surgery and ofeten form patients in recovery?
Yes
Ways to measure oxygen saturation
- Taking an aterial blood sample
- Pulse oximeter
taking an aterial blood sample
- this procedure is more difficult than collection of vrnoud blood sample becasue the arteries in the arm are deeper and the muscular aterial wall is more difficult to punture with a needle
(Take blood and sample it)
Very invasive
