Category: Biomedical Measurements
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What is the Function of a Phonocardiograph?
A phonocardiogram is a recording of the heart sounds and murmurs. The instrument used to make this recording is called the phonocardiograph. The recording of all the heart sounds during a cardiac cycle is termed to as phonocardiography. Phonocardiogram eliminates the subjective interpretation of the heart sounds and makes it possible to evaluate them with…
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Key Factors to Consider in the Design and Operation of Electrocardiograph
There are various factors that must be considered in the design and application of the electrocardiograph. These key factors must be considered by the biomedical engineer as well as the electrocardiograph operator and the physician who interprets the recorded information. We discuss these factors as follows: Frequency distortion The electrocardiograph does not always meet the…
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Functions & Types of Pneumotachometers for Biomedical Measurements
Pneumotachometers are instruments that measure the instantaneous rate of volume flow of respired gases. They can be broadly classified into two types based on the principle of operation: The pneumotachometer is normally used to measure parameters relating to pulmonary function such as forced expiratory volume (FEV), maximum mid-expiratory volume, & peak flow and to generate…
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Key factors that affect or limit Biomedical Measurements
Low measurement ranges – Biomedical instruments are used to measure various medical and physiological parameters. Most of the parameter measurement ranges are quite low compared with non-medical parameters. For example, most biomedical voltages are in the microvolt range and the pressures are also low about 1.93 psi. These general properties of medical parameters limit the…
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Key Features of a Disposable Blood Pressure Sensor
Disposable blood pressure sensors are made of clear plastic so that air bubbles are easily seen Saline flows from an intravenous (IV) bag through the clear IV tubing and the sensor to the patient. This is used to flush out blood out of the tip of the indwelling catheter to prevent clotting. A lever can…
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3 Sources of Noise in Biomedical Measurement Systems
Biomedical measurements involve low-level signals which are susceptible to noise interference. We have 3 common sources of noise in biomedical measurements which are: Improper Grounding Grounding means a low impedance metallic connection to a properly designed ground grid, located in the earth. Placing more than one ground on a signal circuit produces a ground loop…
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Types of Oximeters
The types of Oximeters commonly used to measure percentage oxygen saturation of circulating blood include: Pulse Oximeter The principle of operation of pulse oximeter is based on the concept that the arterial oxygen saturation determinations can be made using two wavelengths. These two wavelengths assume two absorbers namely: The instrument consists of a pair of…
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The Process of Oximetry in Biomedical Measurements
Oximetry is the determination of the percentage oxygen saturation of the circulating arterial blood. Where, [HbO2] is the concentration of oxygenated haemoglobin and [Hb] is the concentration of deoxygenated haemoglobin. The percentage of oxygen saturation in the blood is very important. The oxygen saturation is a bio-constant and is an indication of the performance of…
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Key Considerations in Respiratory Measurements & Instrumentation Involved
Airflow The airflow in the respiratory system is normally laminar. However, during heavy breathing or when there is an obstruction, the airflow may become turbulent. The airflow is laminar unless the Reynolds number of the flow becomes 50,000 or more. When the Reynolds number is small, the viscous force in the flow dominates over the…
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Blood Pressure Measurement
Introduction The blood pressure is considered a good indicator of the status of the cardiovascular system. The blood pressure can be measured by: Indirect methods of Blood Pressure Measurement Examples of indirect methods of blood pressure measurement include: Sphygmomanometer In this method the occlusive cuff is inflated until the pressure exerted by the cuff on…