MPHY3012/M012 Physiological Monitoring

The course forms part of the Electronics with Medical Electronics (B.Eng.), Physics with Medical Physics (B.Sc.), Medical Physics (M.Sci.) and Medical Physics & Bioengineering (B.Sc.(Intercal)) undergraduate degree courses. The course provides an understanding of the theory and practice of transducers and monitoring techniques in medicine and physiology and covers most of the commonly used methods in medical practice with the exception of those derived from imaging and radionuclide methods.

Year 3 and M-level variants

This course can be taken in Year 3 as MPHY3012 or in Year 4 as an M-level variant called MPHYM012. The two variants differ in the amount of coursework, and the pass mark for the M-level variant is 50%.

Aims and Objectives

To provide a sound basic knowledge of the scientific principles and the practical aspects of transducers and physiological monitoring techniques in clinical medicine. The characteristics of the commonly monitored clinical signals will also be described.

To impart knowledge and understanding on a range of important physiological parameters, their magnitudes and signal bandwidth.
To impart knowledge on the theory of commonly used physiological monitoring techniques and provide practical illustrations of their implementation.
To impart knowledge and understanding on the design of practical clinical sensors and transducers.
To provide an understanding of design configurations and constraints when applying sensors to measurements in the clinical environment.

Teaching and exams

Teaching will consist of:

Lectures, 27-30 hours.
Seminars/problem classes, 3-6 hours.
Required written work (essays, problem sheets),15 hours.
Private reading, 30 hours.

The assessment will consist of:

1 Unseen written examination (3 hours) worth 85% of the total course mark.
3 Essay/Problem Sheets completed during term-time worth 15% of the total course mark.

Prerequisites

There are no strict prerequisites.

Description

The course is taken by students from several different backgrounds, physics, electronic engineering and intercalated medical degrees. Medical Engineering is by its nature an interdisciplinary activity requiring working with individuals from various backgrounds, so the course provides a useful introduction to this type of working.

As can be seen from the brief syllabus below, the material in the course covers a very wide range of sensors, transducers and physiological measurements. This is an inevitable consequence of the topic. In general each transducer is described from first principles assuming that the students have little relevant background information. The fundamental principles of the sensing technique are described (with derivations of relevant equations), then the practical implementation of a clinically usable system is presented. Details of any relevant signal processing, and importantly the sources and magnitudes of errors in the technique and its application are then described. Wherever possible, we try and incorporate practical demonstrations of the sensors, some which take place through visits to departments in the hospital where they are in use. The most relevant of the course textbooks are those written with an electronic engineering bias, although "Medical Physics and Biomedical Engineering" by Brown et al. is a highly readable text. Since there is not a single suitable course textbook, both lecturers have a policy of providing copies of course notes for the students.

The assessed coursework usually take the form of two essays (one from each lecturer) plus a problem sheet. Other short non-assessed problem sheets are used where appropriate to judge the degree of understanding of particular topics. The essays are on individual topics (i.e. each student gets a different one), and usually require the student to do some research in the area. For this reason they are usually handed out around the second week of term with an extended deadline of 6-8 weeks for their completion.

Brief Syllabus

Measurement Variables Introduction; Physiological variables: nature of signals, Pressure, force and position, units KPa mm of Hg; Flow and velocity; Gases and ions
Pressure, force and position sensing Bridge-type measuring systems: resistive & reactive; Resistive strain-gauges: pressure volume displacement; Capacitive position sensors; Inductive position sensors; Construction of force and pressure sensors: Isolation, Frequency Response (effect of volume displacement), Resonance Effects; Application examples: Measurement of blood pressure, Measurements of gait and posture
Piezoelectric sensors Piezoelectric materials; Force and pressure sensors; Accelerometers: gait analysis LF; Ultrasonic transducers: ultrasound imaging and flow
Temperature sensing Thermistors: temperature coefficients, linearisation; Thermocouples: reference junctions; Platinum resistance sensor.
Flow, velocity and volume sensors Differential pressure sensors: capacitive & strain gauge (Air Flow); Vane and turbine sensors: Wright respirometer (Air Flow), peak flow meters; Gas Volume Measurement: the Spirometer, the pneumotacograph.
Optical Sensors Basic spectroscopy; Oxygen saturation measurement (the pulse oximeter); Infrared absorption detectors (Capnography); photoacoustic spectroscopy; Ionisation gas detector; Laser Doppler blood flow
Gas and Ion Sensors Reference electrodes; pH and other ion sensors; pO2 and pCO2 sensors; Construction of sensor elements: Practical Problems of membranes/spacers, response times; The blood gas analyser; Transcutaneous blood gas sensors; Paramagnetic oxygen analyser; magneto acoustic spectroscopy; respiratory mass spectroscopy

Core Texts

J. G. Webster (Editor), Medical Instrumentation - Application and Design, Houghton Miflin Co.
L. A. Geddes and L. E. Baker, Principles of Applied Biomedical Instrumentation, J Wiley: New York, 1989.
E. O. Doebelin, Measurement Systems - Application and Design, McGraw Hill, 1990
B. H. Brown, R. H. Smallwood, D. C. Barber, P. V. Lawford, and D. R. Hose. Medical Physics and Biomedical Engineering. IOP Publishing
R. Aston, Principles of Biomedical Instrumentation, Merrill Publishing, 1991.
R. S. C. Cobbold, Transducers for Biomedical Instrument, Wiley Interscience, 1974.
V. C. Madama, Pulmonary Function Testing, Delmar Publishing Inc. 1993.
R. K. Hobbie, Intermediate Physics for Medicine & Biology, Springer Verlag, 1997.
M. W. Denny, Air and Water, Princeton Univiversity Press, 1993.

UCL DEPARTMENT OF MEDICAL PHYSICS AND BIOENGINEERING