- Email: [email protected]
The Role of the Biomedical Engineer in Pressure Sore Prevention - A Personal View
26
Journal of Tissue Viability 1998 Vol 8 No 1
THE ROLE OF THE BIOMEDICAL ENGINEER IN PRESSURE SORE PREVENTION - A PERSONAL VIEW IAN SWAIN Consultant Biomedical Engineer, Department ofMedical Physics and Biomedical Engineering, Salisbury District Hospital Definition The formal definition of rehabilitation engineering is: the application of physical science and engineering principles in collaboration with the medical and life sciences to restore the individual to the maximum level of mental, physical and social well being and function. This definition, although not written exclusively with tissue viability and pressure sore prevention in mind, is nevertheless directly relevant and I will refer to the points it raises throughout this article.
It would be expected that the Chartered Engineer would be
more involved in the areas of education, research, product development and management. The Engineering Technician being primarily responsible for manufacture of one-off products and testing, and the Incorporated Engineer working in any of the above areas, but concentrating primarily on the practical aspects. Although the number of BMEs in Pressure Sore Prevention is small, the effect they have can be quite substantial. There are a number of functions the BME can undertake as part of the pressure sore prevention team. These include: a) education,
What is a Biomedical Engineer? Basically a Biomedical Engineer (BME) is a person who applies engineering techniques to the study of clinical and medical science. The majority will have a primary qualification in an engineering subject usually electronic, electrical or mechanical engineering. Due to the confusion that surrounds the public perception of engineering, is often used by a variety of people the term 'engineer' whether or not it is valid. However, for the purpose of this article the term 'engineer' will apply to only those people who have a formal engineering qualification recognised by the Engineering Council and those who are emolled in a formal training programme leading to such a qualification 1. There are three grades of membership of the Engineering Council. 1) Chartered Engineer (CEng) A graduate from an accredited engineering course who has at least four years post graduate experience at least two of which are in a position of responsibility. This cannot be achieved before the age of 26 and should be thought of as being roughly equivalent to MRCP, FRCS, MRCPath etc.
2) Incorporated Engineer (!Eng) A holder of an accredited diploma (HND or equivalent) plus experience. Comparable to an experienced paramedic or nurse eg senior sister. 3) Engineer Technician (Eng Tech) A holder of an accredited qualification such as ONC/OND with considerable experience in the practical aspects of the job.
b) research, c) equipment evaluation and selection, d) 'one-off' designs and modifications, e) development of new products and techniques.
Education With the number of BMEs being so small it is vital that their knowledge is disseminated as widely as possible. Therefore they have a responsibility to be involved in education at all levels, from the teaching of student nurses through to the supervision of experienced staff studying for post graduate degrees. However, as there are so few, it is impossible to reach that many people by direct teaching. Therefore, there is a great responsibility on BMEs to publish widely and in all levels of Journals including nursing, medical, therapy, and management, fo_r in these days of evidence based medicine, it is vitally important that health service management understands all aspects of the prevention and treatment of pressure sores. Part of this educational role must be to teach the basics of biomechanics so that the cause and possible prevention of pressure sores can be understood. For example, this starts from the basic question - what is pressure? Pressure is force per unit area (force = mass x gravity). Therefore if you want to reduce the pressure on a person on a static system, the only thing you can change is the contact area (unless you take the person to the moon where the gravitational constant is only 1/6 of that on earth), and the
Choice of Cover
Waterproof wipedown cover
Waterproof towelling cover
F/O:tech "These cushions provide a financially competitive option and are among the few moulded cushions available for general patient use" (1) Medical Support Systems introduces the NEW EXTENDED range of Flo-tech Cushions designed
There are 5 seat cushions and 1 supportive back
lniage
cushion within the MSS Flo-tech range. All have proven clinical effectiveness (2)
"Posture and pressure are important .aetiological factors in pressure sore development in the seated patient" (1)
for comfort, good posture and effective pressure reduction. 1. Young T. British Journal of Nursing. 1997 Vol.6 No.8 455-459.
2. Medical Support Systems Technical Bulletin 1997.
MEDICAL SUPPORT SYSTEMS LTD.
Name ......................................................................Job Title .................................Tel ....................................
Nantgarw Business Park Cardiff CF4 7QU U.K. Tel : (01443) 849200 Fax :(01443) 843377 , E-Mail: [email protected] i
nrn;:inic;:itinn I ArlrlrPCC
,,-1~~ ~
sendme an_lhfarmatlonpatk 6ri the Ni$tl~Xf~N Please ask your representative to contact me
0
28
Journal of Tissue Viability 1998 Vol 8 No 1
only way you can increase the contact area is by having the person sink into the surface to a greater depth. It does not matter what the support surface is made of, it is only the contact area and the uniformity of that contact that is important, For example, viscoelastic foams make no difference to the interface pressure just because they recover more slowly. If, however, the person is supported over a greater area, then this pressure will be reduced. The above is only one example of the role of the BME in the educational side of pressure sore prevention. The same is equally true of the definition of terms that are frequently used, often incorrectly, by companies trying to sell their products. This includes terms such as vapour permeability, hardness, fatigue, density and above all shear, which is a term that is much used but seldom correctly. A full discussion of all these terms, in particular shear, is beyond the scope of this article, however, it is hoped that it could be the subject of a future paper in this Journal.
Research
This is obviously the route by which most BME's get involved in pressure sore prevention. Although the field is an unglamourous one, there is a vast amount still to be done, whether the BME is working in the NHS, in a University or in a private company. There are also a large number of different aspects which are 'crying out' for more work. These can be largely physiological studies, such as the effect that different cycle times of alternating pressure systems have on blood flow, or mechanical engineering projects such as the design of an indentor to objectively assess when a mattress is no longer acceptable for clinical use. The possibilities are only limited by the BMEs imagination. However, it is important that before the BME embarks on any research programme they must obtain a good working knowledge of the prevention and treatment of pressure sores. This is best obtained by working closely with the tissue viability nurse (TVN), going on the wards together, finding out what the real problems are, and targeting the research at a specific clinical problem. All too often, research can be of great interest to the person undertaking it but of little practical value to clinical practice. This can in tum lead clinical staff to believe that research is a waste of time and not relevant to them. This could not be further from the truth and can be so easily avoided if multi-disciplinary working is actively encouraged. The other area in which the BME can make a major contribution is in providing assistance and supervision of other professional 's research projects. The background of the BME will nearly always have been through the traditional engineering route so that the planning, undertaking, analysis and reporting of experimental procedures has become second nature. This should include minimisation of errors in the measurement procedure as well as ensuring that the measurement system is actually measuring the required parameters. This might seem obvious, but all too often the
desire to measure 'something' takes precedence over the consideration of whether that measurement is going to provide the answer to the given problem. The weakness that most BME's have, and it is a serious one, is in a lack of formal training in statistical methods. I personally never had a single lecture on statistics despite taking 2 mathematics 'A' levels and an engineering degree. As a result, all my statistical knowledge or lack of it, has been acquired rather than taught. Therefore it is better to get statistical advice from a statistician than from an engineer. Or better still, from a statistically significant number of statisticians, but expect a wide standard deviation.
Equipment Selection I Testing
The BME's role in equipment testing and selection is obviously very similar to that in research, in that it involves the development of measurement systems. However, unlike research, the protocols necessary to undertake meaningful comparisons are usually well established usually in previous research programmes. What is important is the objectivity and repeatability of the measurements made and the relevance of those measurements to the pattern of clinical use to which the product is going to be exposed. For example if a cushion is going to be used mainly with spinal patients, is there any relevance if all the comparisons are taken with young healthy volunteers (often a euphemism for medical students). The problem with such studies or comparisons is the time that they take. Therefore it is more cost effective to have a technician undertake the actual measurements, with the BME being responsible for planning the trial, the validity of the measurements made and the analysis of the data. Such objective tests can be vital as in our own experience several products designed to prevent pressure sores actually gave higher pressures than the standard marbled covered contract mattress. Without this check those products would have been trialled on the wards to the detriment of the patients. Once any comparison has been undertaken, the BME has a role in the selection of equipment. This is primarily as a watchdog to see if the manufacturers claims are valid and to ask technical questions. Once again as with research, it is essential that the BME works as part of a multi-disciplinary team so that all aspects of a product can be considered. I recently chaired a group to select a new contract NHS mattress. The initial specification was drawn up by a wide range of healthcare professional including nurses, medical staff, BME's, NHS Supplies and manufacturers, with the final decision being taken by 2 BME's, an infection control nurse, a TVN, and the nursing advisor and two buyers from NHS Supplies.
One-Off Designs I Modification I New Products
Virtually all BME's will have been involved in design at some time in their careers. It is normally the desire to design and innovate that led then to decide upon engineering as a career in the first place. Secondly, those who choose to
Journal of Tissue Viability 1998 Vol 8 No 1
29
specialise in Biomedical or Rehabilitation Engineering are those who want to be involved in a 'hands on' way, being involved in the design process from the specification to the delivery. This does not happen in many other branches of engineering where an individual, unless a senior executive, does not have a complete picture of the whole project. Even then the senior executive does not have the chance to actually manufacture anything himself. It is this immediacy and involvement at all stages that leads people into Biomedical Engineering as a career. Also, unlike those of many engineers, none of the things you design are likely to kill people unless you are very bad at your job.
accrued from one-off designs and modifications. After a period of time this clinical experience leads the BME to realise that there are patients whose needs cannot be met by existing equipment. This is an area where clinical experience and engineering principles meet. The BME has to consider many factors such as cost, aesthetics, ease of manufacture and above all patient safety in taking an idea from a design concept to a finished product. This design process is equally true whether the product be a new type of cushion or a better method of assessing the viability of compromised tissue.
Therefore the BME has several areas in which he/she can make a contribution. They can be directly involved in clinics seeing patients and assessing them in conjunction with their clinical colleagues to determine the best plan of action. The majority of the BME's time in this field is going to be in assessment, determining the 'fit' of prescribed item whether it be a cushion or an orthosis, to ensure that there is not going to be any problem caused to the skin. The advantage of using a BME in this role rather than a physiological measurement technician is that the BME sees the problems for themselves. Therefore if the 'fit' is not ideal, they can determine what modifications are necessary or if indeed nothing commercial exists to meet the patients needs and therefore a 'special' or 'one off' design is needed. The BME can then take on the design remit once it has been agreed upon by the whole clinical team - medical, nursing, therapy and most important, the patient and carer. It is all too easy to design something which is not relevant to the patient's needs. This is even easier to get wrong if you, as a BME, rely on the information being relayed to you through a third party ie a written or worse still a verbal request, rather than being present at the decision making process in person.
In conclusion I think that the BME does have a major contribution to make in the field of tissue viability. I suppose that comes as no surprise to readers otherwise it would mean that I have been wasting my time for the past fifteen years it also pays the mortgage. However, I strongly feel that this contribution is greater, and indeed, only relevant, if the BME is a central member of the multidisciplinary clinical team. It just does not work for the BME to be detached from clinical realities and to be given 'projects' usually by the medical staff. To that end our department carries a heavy clinical case load and we employ physiotherapists, occupational therapists and nurses to work alongside engineers and technicians. We do not actually employ any medical staff but we do work closely with a number from a variety of primary disciplines who are friendly, if not always tame.
Development of New Products and Techniques
1.
The development of new products should flow directly from the clinical involvement described above and the experience
Conclusion
Address for Correspondence
Dr I Swain, Department of Medical Physics and Biomedical Engineering, Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ.
References
Definitions, roles and responsibilty in Rehabilitation Engineering - A statement by the Institute of Physics and Engineering in Medicine.
Lymphoedema Study Days The Centre for Research and Implementation of Clinical Practice is entering the field of lymphoedema both in terms of research_and education and having secured the services of a specialist in lymphoedema the Centre is holding two study days in 1998. Tuesday, 31 March
Introduction to the management of lymphoedema and associated conditions
Thursday, 7 April
Compression therapy in lymphoedema
The venue will be the Wolfson Institute of Health Sciences, Thames Valley University, 32-38 Uxbridge Road, W5 2BS. The cost will be £45 to include lunch. Further information and an application form can be obtained from Christine Moffatt at the Centre for Research and Implementation of Clinical Practice, Wolfson Institute of Health Sciences, Thames Valley University, 32-38 Uxbridge Road, W5 2BS, tel: 0181 280 5020.
Journal of Tissue Viability 1998 Vol 8 No 1
THE ROLE OF THE BIOMEDICAL ENGINEER IN PRESSURE SORE PREVENTION - A PERSONAL VIEW IAN SWAIN Consultant Biomedical Engineer, Department ofMedical Physics and Biomedical Engineering, Salisbury District Hospital Definition The formal definition of rehabilitation engineering is: the application of physical science and engineering principles in collaboration with the medical and life sciences to restore the individual to the maximum level of mental, physical and social well being and function. This definition, although not written exclusively with tissue viability and pressure sore prevention in mind, is nevertheless directly relevant and I will refer to the points it raises throughout this article.
It would be expected that the Chartered Engineer would be
more involved in the areas of education, research, product development and management. The Engineering Technician being primarily responsible for manufacture of one-off products and testing, and the Incorporated Engineer working in any of the above areas, but concentrating primarily on the practical aspects. Although the number of BMEs in Pressure Sore Prevention is small, the effect they have can be quite substantial. There are a number of functions the BME can undertake as part of the pressure sore prevention team. These include: a) education,
What is a Biomedical Engineer? Basically a Biomedical Engineer (BME) is a person who applies engineering techniques to the study of clinical and medical science. The majority will have a primary qualification in an engineering subject usually electronic, electrical or mechanical engineering. Due to the confusion that surrounds the public perception of engineering, is often used by a variety of people the term 'engineer' whether or not it is valid. However, for the purpose of this article the term 'engineer' will apply to only those people who have a formal engineering qualification recognised by the Engineering Council and those who are emolled in a formal training programme leading to such a qualification 1. There are three grades of membership of the Engineering Council. 1) Chartered Engineer (CEng) A graduate from an accredited engineering course who has at least four years post graduate experience at least two of which are in a position of responsibility. This cannot be achieved before the age of 26 and should be thought of as being roughly equivalent to MRCP, FRCS, MRCPath etc.
2) Incorporated Engineer (!Eng) A holder of an accredited diploma (HND or equivalent) plus experience. Comparable to an experienced paramedic or nurse eg senior sister. 3) Engineer Technician (Eng Tech) A holder of an accredited qualification such as ONC/OND with considerable experience in the practical aspects of the job.
b) research, c) equipment evaluation and selection, d) 'one-off' designs and modifications, e) development of new products and techniques.
Education With the number of BMEs being so small it is vital that their knowledge is disseminated as widely as possible. Therefore they have a responsibility to be involved in education at all levels, from the teaching of student nurses through to the supervision of experienced staff studying for post graduate degrees. However, as there are so few, it is impossible to reach that many people by direct teaching. Therefore, there is a great responsibility on BMEs to publish widely and in all levels of Journals including nursing, medical, therapy, and management, fo_r in these days of evidence based medicine, it is vitally important that health service management understands all aspects of the prevention and treatment of pressure sores. Part of this educational role must be to teach the basics of biomechanics so that the cause and possible prevention of pressure sores can be understood. For example, this starts from the basic question - what is pressure? Pressure is force per unit area (force = mass x gravity). Therefore if you want to reduce the pressure on a person on a static system, the only thing you can change is the contact area (unless you take the person to the moon where the gravitational constant is only 1/6 of that on earth), and the
Choice of Cover
Waterproof wipedown cover
Waterproof towelling cover
F/O:tech "These cushions provide a financially competitive option and are among the few moulded cushions available for general patient use" (1) Medical Support Systems introduces the NEW EXTENDED range of Flo-tech Cushions designed
There are 5 seat cushions and 1 supportive back
lniage
cushion within the MSS Flo-tech range. All have proven clinical effectiveness (2)
"Posture and pressure are important .aetiological factors in pressure sore development in the seated patient" (1)
for comfort, good posture and effective pressure reduction. 1. Young T. British Journal of Nursing. 1997 Vol.6 No.8 455-459.
2. Medical Support Systems Technical Bulletin 1997.
MEDICAL SUPPORT SYSTEMS LTD.
Name ......................................................................Job Title .................................Tel ....................................
Nantgarw Business Park Cardiff CF4 7QU U.K. Tel : (01443) 849200 Fax :(01443) 843377 , E-Mail: [email protected] i
nrn;:inic;:itinn I ArlrlrPCC
,,-1~~ ~
sendme an_lhfarmatlonpatk 6ri the Ni$tl~Xf~N Please ask your representative to contact me
0
28
Journal of Tissue Viability 1998 Vol 8 No 1
only way you can increase the contact area is by having the person sink into the surface to a greater depth. It does not matter what the support surface is made of, it is only the contact area and the uniformity of that contact that is important, For example, viscoelastic foams make no difference to the interface pressure just because they recover more slowly. If, however, the person is supported over a greater area, then this pressure will be reduced. The above is only one example of the role of the BME in the educational side of pressure sore prevention. The same is equally true of the definition of terms that are frequently used, often incorrectly, by companies trying to sell their products. This includes terms such as vapour permeability, hardness, fatigue, density and above all shear, which is a term that is much used but seldom correctly. A full discussion of all these terms, in particular shear, is beyond the scope of this article, however, it is hoped that it could be the subject of a future paper in this Journal.
Research
This is obviously the route by which most BME's get involved in pressure sore prevention. Although the field is an unglamourous one, there is a vast amount still to be done, whether the BME is working in the NHS, in a University or in a private company. There are also a large number of different aspects which are 'crying out' for more work. These can be largely physiological studies, such as the effect that different cycle times of alternating pressure systems have on blood flow, or mechanical engineering projects such as the design of an indentor to objectively assess when a mattress is no longer acceptable for clinical use. The possibilities are only limited by the BMEs imagination. However, it is important that before the BME embarks on any research programme they must obtain a good working knowledge of the prevention and treatment of pressure sores. This is best obtained by working closely with the tissue viability nurse (TVN), going on the wards together, finding out what the real problems are, and targeting the research at a specific clinical problem. All too often, research can be of great interest to the person undertaking it but of little practical value to clinical practice. This can in tum lead clinical staff to believe that research is a waste of time and not relevant to them. This could not be further from the truth and can be so easily avoided if multi-disciplinary working is actively encouraged. The other area in which the BME can make a major contribution is in providing assistance and supervision of other professional 's research projects. The background of the BME will nearly always have been through the traditional engineering route so that the planning, undertaking, analysis and reporting of experimental procedures has become second nature. This should include minimisation of errors in the measurement procedure as well as ensuring that the measurement system is actually measuring the required parameters. This might seem obvious, but all too often the
desire to measure 'something' takes precedence over the consideration of whether that measurement is going to provide the answer to the given problem. The weakness that most BME's have, and it is a serious one, is in a lack of formal training in statistical methods. I personally never had a single lecture on statistics despite taking 2 mathematics 'A' levels and an engineering degree. As a result, all my statistical knowledge or lack of it, has been acquired rather than taught. Therefore it is better to get statistical advice from a statistician than from an engineer. Or better still, from a statistically significant number of statisticians, but expect a wide standard deviation.
Equipment Selection I Testing
The BME's role in equipment testing and selection is obviously very similar to that in research, in that it involves the development of measurement systems. However, unlike research, the protocols necessary to undertake meaningful comparisons are usually well established usually in previous research programmes. What is important is the objectivity and repeatability of the measurements made and the relevance of those measurements to the pattern of clinical use to which the product is going to be exposed. For example if a cushion is going to be used mainly with spinal patients, is there any relevance if all the comparisons are taken with young healthy volunteers (often a euphemism for medical students). The problem with such studies or comparisons is the time that they take. Therefore it is more cost effective to have a technician undertake the actual measurements, with the BME being responsible for planning the trial, the validity of the measurements made and the analysis of the data. Such objective tests can be vital as in our own experience several products designed to prevent pressure sores actually gave higher pressures than the standard marbled covered contract mattress. Without this check those products would have been trialled on the wards to the detriment of the patients. Once any comparison has been undertaken, the BME has a role in the selection of equipment. This is primarily as a watchdog to see if the manufacturers claims are valid and to ask technical questions. Once again as with research, it is essential that the BME works as part of a multi-disciplinary team so that all aspects of a product can be considered. I recently chaired a group to select a new contract NHS mattress. The initial specification was drawn up by a wide range of healthcare professional including nurses, medical staff, BME's, NHS Supplies and manufacturers, with the final decision being taken by 2 BME's, an infection control nurse, a TVN, and the nursing advisor and two buyers from NHS Supplies.
One-Off Designs I Modification I New Products
Virtually all BME's will have been involved in design at some time in their careers. It is normally the desire to design and innovate that led then to decide upon engineering as a career in the first place. Secondly, those who choose to
Journal of Tissue Viability 1998 Vol 8 No 1
29
specialise in Biomedical or Rehabilitation Engineering are those who want to be involved in a 'hands on' way, being involved in the design process from the specification to the delivery. This does not happen in many other branches of engineering where an individual, unless a senior executive, does not have a complete picture of the whole project. Even then the senior executive does not have the chance to actually manufacture anything himself. It is this immediacy and involvement at all stages that leads people into Biomedical Engineering as a career. Also, unlike those of many engineers, none of the things you design are likely to kill people unless you are very bad at your job.
accrued from one-off designs and modifications. After a period of time this clinical experience leads the BME to realise that there are patients whose needs cannot be met by existing equipment. This is an area where clinical experience and engineering principles meet. The BME has to consider many factors such as cost, aesthetics, ease of manufacture and above all patient safety in taking an idea from a design concept to a finished product. This design process is equally true whether the product be a new type of cushion or a better method of assessing the viability of compromised tissue.
Therefore the BME has several areas in which he/she can make a contribution. They can be directly involved in clinics seeing patients and assessing them in conjunction with their clinical colleagues to determine the best plan of action. The majority of the BME's time in this field is going to be in assessment, determining the 'fit' of prescribed item whether it be a cushion or an orthosis, to ensure that there is not going to be any problem caused to the skin. The advantage of using a BME in this role rather than a physiological measurement technician is that the BME sees the problems for themselves. Therefore if the 'fit' is not ideal, they can determine what modifications are necessary or if indeed nothing commercial exists to meet the patients needs and therefore a 'special' or 'one off' design is needed. The BME can then take on the design remit once it has been agreed upon by the whole clinical team - medical, nursing, therapy and most important, the patient and carer. It is all too easy to design something which is not relevant to the patient's needs. This is even easier to get wrong if you, as a BME, rely on the information being relayed to you through a third party ie a written or worse still a verbal request, rather than being present at the decision making process in person.
In conclusion I think that the BME does have a major contribution to make in the field of tissue viability. I suppose that comes as no surprise to readers otherwise it would mean that I have been wasting my time for the past fifteen years it also pays the mortgage. However, I strongly feel that this contribution is greater, and indeed, only relevant, if the BME is a central member of the multidisciplinary clinical team. It just does not work for the BME to be detached from clinical realities and to be given 'projects' usually by the medical staff. To that end our department carries a heavy clinical case load and we employ physiotherapists, occupational therapists and nurses to work alongside engineers and technicians. We do not actually employ any medical staff but we do work closely with a number from a variety of primary disciplines who are friendly, if not always tame.
Development of New Products and Techniques
1.
The development of new products should flow directly from the clinical involvement described above and the experience
Conclusion
Address for Correspondence
Dr I Swain, Department of Medical Physics and Biomedical Engineering, Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ.
References
Definitions, roles and responsibilty in Rehabilitation Engineering - A statement by the Institute of Physics and Engineering in Medicine.
Lymphoedema Study Days The Centre for Research and Implementation of Clinical Practice is entering the field of lymphoedema both in terms of research_and education and having secured the services of a specialist in lymphoedema the Centre is holding two study days in 1998. Tuesday, 31 March
Introduction to the management of lymphoedema and associated conditions
Thursday, 7 April
Compression therapy in lymphoedema
The venue will be the Wolfson Institute of Health Sciences, Thames Valley University, 32-38 Uxbridge Road, W5 2BS. The cost will be £45 to include lunch. Further information and an application form can be obtained from Christine Moffatt at the Centre for Research and Implementation of Clinical Practice, Wolfson Institute of Health Sciences, Thames Valley University, 32-38 Uxbridge Road, W5 2BS, tel: 0181 280 5020.