Journal of Medical Engineering & Technology
ISSN: 0309-1902 (Print) 1464-522X (Online) Journal homepage: http://www.tandfonline.com/loi/ijmt20
A practical approach to patenting R. S. Crespi To cite this article: R. S. Crespi (1977) A practical approach to patenting, Journal of Medical Engineering & Technology, 1:5, 259-263, DOI: 10.3109/03091907709162190 To link to this article: http://dx.doi.org/10.3109/03091907709162190
Published online: 09 Jul 2009.
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18. Judet, J., Judet, R., Lagrange, J. and Dunoyer, J. Resection reconstruction of the hip. Arthroplasty with acrylic proathesis. (Livingstone, Edinburgh & London, 1954). 19. Charnley, J. (1967). Fractors in the Design of an Artificial Hip Joint. Proceedings, Institution of Mechanical Engineers, 181 (3J) 104-111. 20. Weber, B. G., Stiihmer, G. and Semlitsch, M. (1974).
Erfahrungen mit dem Kunststoff Polyester als Komponente der Rotationstotalprothese des Huftgelenkes. (Experience with poly-ester as a component of the rotation total prosthesis for the hip-joint). Zeitschrift fur Orthopadie und ihre Grenzgebiete, 112 ( 5 ) 1106-1112.
21. Sundal, B., Kavlie, H. and Christiansen, T. (1974). Total
hip replacement with a new frunnion-bearing prosthesis (the Christiansen prosthesis). Acta Chirurgica Scan-
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dinavica, 140 (3) 189-193. 22. Schmittgmnd, G. D., Kenner, G. H. and Brown, S . D. (1973). In vivo and in vitro changes in strength of orthopaedic calcium aluminates. Journal of Biomedical Materials Research, Symposium No. 4, 435. 23. Boutin, P. (1972). Arthroplastie total de la hanche par
24. Geduldig, D., Lade, R., Prlissner, P., Willert, H-G., Zichner, L. and Doerre, E. Experimental Investigations
of dense Alumina Ceramic for Hip and Knee Joint Replacements. In Advances in Artificial Hip and Knee Joint Technology, ed. M. Schaldach and D. Hohmann, pp. 434445 (Springer, Berlin, 1976). 25. Griss, P., Krempien, B., v. Andrian-Werburg, H., Heimke, G. and Fleiner, R. (1 973). Experimentelle Untersuchung zur Gwebsvertraglichkeit oxidkeramischer (A12 0 3 ) Abriebteilchen. Archiv f u r orthopadische urld Unfall-Chirurgie, 76. 270-279. 26. Griss, P., Heimke, G., Krempien, B. and Jentschura, J.
Ceramic Hip Joint Replacement-Experimental Results and Early Clinical Experience. In ‘Advances in Artificial Hip and Knee Joint Technology’ ed. M. Schaldach and D. Hohmann, page 446 (Springer, Berlin, 1976). 27. Boutin, P. (1974). Les prostheses totales de la hanche en alumine. L‘ancrage direct sans ciment dans 50 cas. (Total hip prosthesis made of dense ceramics (Fritted alumina). A Study of the attachment to bone.) Revue de Chirurgie Orthopidique et Reparatrice de I‘dppareil Moteur, 60 (3) 233-245.
prosthese en alumine fritb. (Total hip arthroplasty made of dense ceramics (fritted alumina)). Revue de Chirurgie Othopkdique et Reparatrice de I‘Appareil Moteur, 58 (3) 229.
A practical approach to patenting R. S. Crespi National Research Development Corporation, PO Box 236, Kingsgate House, 6 6 / 6 7 Victoria Street, London S W l E 6SL, U K .
This article is intended to draw attention to some of the pitfalls which await the unwary inventor in the fields of biology and medical science should he wish to patent his new invention. Aspects of British, United State3 and European patent lm are outlined and practical aspects of making a patent application ure discussed. The article concludes with a short note on copyright. There appears to be a wave of interest at the present time in the subject of patents and articles are appearing on a variety of aspects of the patent law from particular standpoints. The justification for yet another contribution on this topic must be the fact that the patent laws are in a period of change and the opportunity is a good one, therefore, to present an account which is both an introduction for the benefit of those who are newcomers to patent matters and a refresher for those who have some working knowledge of it already. Many scientific workers are brought up in the philosophy of research and publication with the result that, when one believes he has produced some new finding of’ interest to the scientific community, the first impulse is to let the, world know about it as soon as possible. This excellent maxim may, however, need some qualification because the published information can often be capable of practical exploitation for commercial ends as well as enriching the state of scientific knowledge. I n these circumstances there is no reason why the person who generates an innovation of this kind should not benefit from it by recognition in both fields of human activity. Industrial research workers are, of course, orientated towards the practical purposes of their research for the benefit of their employer and, being already converted, they are in no need of any message. Other kinds of researcher who d o not have industrial backing may take the view that commercial exploitation of their research is too uncertain, tedious, and generally not suited to their talents, and in the majority of cases they are probably right. On the other hand, if they take the precaution of protecting themselves by the filing of a patent application September, 1977
before publishing any results which strike them as having potential practical significance for industry, there is a reasonable chance that some share in the commercial development may be possible for them by association with it technically or financially by means of a modest royalty on use of the invention. The same precaution applies where the new process or device is to be put into use or subjected to clinical trial in a public manner. The steps necessary for the protection of an invention by means of a patent are generally well known in outline. Thus, if the particular finding is novel and amounts to a sufficiently significant advance upon previous knowledge, and offers the prospect of being of practical value in an industrial context, the process of protecting the invention begins with the filing of an application at the Patent Office before it is in any way publicised or put into public use. 1 have used the term “finding” at this stage to cover generally the kinds of subject matter that can be patented. We can briefly enumerate the various categories as processes, products (and articles), apparatus (and devices), methods of treatment and methods of testing. However, we should note that not all of these items can be patented to the same extent in every country, and the whole subject has its share of ifs and buts under each heading. I do not propose to offer a n exhaustive definition of each category of patentable invention, but some indication of the sorts of things we are concerned with must be given. By “processes” we mean manipulation of some material by mechanical, electrical, chemical or any other procedure for an economic purpose and, usually, to give rise to a vendible product. “Product” can mean any article or material (including a pure substance and a chemical 259
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composition) resulting from some process of assembly, preparation, or extraction. Apparatus carries its ordinary and very general connotation, including any form of equipment or gadgetry. Methods of treatment are, strictly speaking, included under the heading of processes, although in many cases it seems more appropriate to use method terminology, especially where the substrate acted upon is living, for example plants or animals. To be pateiitable the paiiiciilai finding must be new, inventive and useful in some way, and these three requirements are the criteria of patentability in most systems of patent law yet devised. In principle I suppose few would quarrel with the idea that a patent monopoly should only be granted to someone if his contribution is really new and ingenious and lies at least a little way outside the normal track of the day to day routine activities of scientific workers. The difficulty lies in the application of this test in the absence of any clear method of quantifying the conception of what constitutes invention. To make matters worse, the Patent Office Examiner, who is the person we have to convince that an invention has been made, is entitled and indeed required to judge what is offered to him against the background of all previously recorded knowledge, this being referred to by the now universally used term “the prior art”. In general the prior art includes everything on publicly available record or in public use before the inventor’s patent application is filed (the .US patent system has a more sophisticated approach to this question which I will mention later). All prior published documents are citable by the Examiner irrespective of whether they are scientifically well founded or mere paper proposals or even mere science fiction. The Examiner is apt to combine bits from separate documents and make up an artificial construction or “mosaic” in order to argue that the inventor’s contribution lacks the requisite degree of novelty or inventiveness. Inventors do not always realise that the widely enibracing extent of the prior art also jncludes all that they have themselves published or put to use in a public manner. Some tend to regard it as harsh and unfair that the law makes no exception in respect of their own publications. For inventors who regularly publish their work, therefore, a matter of major importance must be faced at the outset, namely, the relationship between patenting policy and u policy of rapid publication and the extent to which the one places inhibitions on the other. In fact this problem can easily be overestimated, and one often finds that it diminishes when examined coolly and with patience and a willingness to seek a compromise solution. There is an important difference between European and United States patent law on this topic, and therefore it would be prefer3ble to look further at this particular problem in the zontext of a brief review of some of the separate patent legal systems, and to these we now turn.
British patent law The present British patent law is covered basically by the 1949 Patents Act, but there is to be a 1977 Patents Act which will come into force probably early in 1978, so that Ne can now begin to speak of the old law and the new aw. Dealing first with the publication conflict mentioned ibove, one helpful factor in the past has been the xivileged position of certain journals of and meetings held by Learned Societies which have been exempted from the general rule that publication prior to filing a patent ipplication automatically deprives the patent of validity. rhis provision has been particularly attractive to academic research workers and has sometimes been believed to be wider in scope that it really is. The Learned Society 260
provision is of restricted territorial application, but it has often been grasped as the only lifeline to save at least the UK patent position. A change of major importance in the new British law is that publication at Learned Society meetings, or in the journals of such societies, will no longer have the protected status enjoyed in the past and will be treated as part of the so-called “prior art”. Consequently if patent protection is not sought before publication of this kind occiirs the chances of securing protection later are diminished to the extent that t h e publication reveals the essentials of the invention and enables the skilled reader to put it into practice, or renders it obvious. A t this point it would be desirable to note that publication in the legal sense also includes disclosures in theses in libraries, talks and demonstrations on Open Days, colloquia, lectures and any other way of making the invention available to the public. Related to the Learned Society provision is one which at present applies to certain types of exhibition at which display of the invention, usually an item of equipment, is protected. The new version of this provision involves a considerable restriction of the privilege, and inventors who are accustomed to participate at such exhibitions should check their position carefully in future. It is important to be clear about the question of clinical trials and, following on from this, the extent to which an invention may be put into use after the trial period without jeopardising the patent position. Reasonable trial and experimental testing of a drug or device do not in themselves constitute a prior use which would prejudice a later-filed patent application, but the problem is that it is often difficult to arrange such trials without a certain amount of leakage of information and even publicity, with the result that the invention is effectively pre-disclosed before anyone has thought about the question of patent protection; and by then it is often too late. Many inventors are unaware of this and will often launch their eventual patenting attempt on the basis that the device has been successfully used quite openly by doctors and nurses for a considerable period of time. I n some cases, of course. practical trials have to take place in a public manner, and the old law catered for that by allowing a period of one year for public working in this special category of invention before the patent application was filed. The new law is not explicit on this topic and, until one knows how these matters will be interpreted, it will be advisable to exercise caution. Under the old law any use of an invention, after the trial period, would invalidate a patent based on a laterfiled application because it would be either a prior public use o r a prior secret use and both these were grounds of invalidating and hence of revocation of the patent. Consequently it was necessary to make up one’s mind about the question of patents before the method or device was put into routine use, and it probably made little real difference whether the intended use was commercial or not and whether it could be carried out without the knowledge of it coming into the possession of the public. The new law is possibly less clear on this point because, for the purpose of refusing a patent application o r of invalidating a patent, the anticipatory use must be a matter which has been made available to the public. Thus, if the invention is an item of equipment for use in a laboratory to which the public do not normally have access, for example a hospital laboratory, one has to ask whether it is available; possibly it can be said to be available to the public in the sense that the use has been carried out for the benefit of patients, even though they did not know precisely what method or device was in fact used. Formerly it was possible to initiate patent action by presenting to the Patent Office a specification of the invention in a provisional manner. In the provisional specificaJournal of Medical Engineering and Technology
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Luxembourg, Switzerland and France have ratified it, enabling the Convention to enter into force next month, although the European Patent Office will probably not open for business until the summer of 1978. Anyone seeking patent protection in the relevant states or a designated number of them can proceed by means of a single patent application in the European Patent Office which, if successful, will result in the grant of a bundle of separate patents for the designated states. In this Convention we have not yet reached the concept of a single unitary patent for the aggregate territories of the various states but some years ahead of us there lies such a goal in the form of the Community Patent System (dealt with in the Community Patent Convention) covering the EEC as a whole. The European Patent Convention is in fact a body of substantive patent law, and regulations which will control the procedure of obtaining protection in the states which the applicant has designated. The general character of this law, for example, its rules governing patentability. is nou becoming the norm to which many European states art conforming their own individual strictly national paten1 laws. It is important to realise that the latter will continut to exist as separate systems and patenting routes alongsidt the European system and to some extent perhaps competi tive with it as regards cost. The following remarks on patentability apply both tc national and European laws. As to the general character of the new laws and thc type of subject matter that can be patented, engineers an( physicists will find little change from past practice. Thc list of exclusions from patentability in the European lav includes discoveries, aesthetic creations, schemes, rules an( methods for performing mental acts, computer program and presentations of information, but this negativc approach is already familiar to inventors in these fields Professional advice should however always be sough before ruling out possibilities in this area. The impact of European law is much greater in thi chemical and biological fields. For the chemist, produc patents for new substances will continue in UK and wil now also be obtainable in Europe as well as the type o process patent which has been the more usual form o protection allowed previously under national laws of mos European states. New uses of old substances will also b patentable in a restricted way. In the biological field, th patentability of substances or devices is in conformity wit1 what has been stated above. As to processes, however, th question is more complex. “Essentially biological” pro cesses for the production of plants or animals are unpatenl able but the interpretation of this phrase is not clear-cul It seems to suggest absence of technical interventior Patents for microbiological processes and products ar specifically allowable. Where a new strain of micrc organism is involved, it must be deposited in an officiz culture collection and made publicly available when th specification is first published. Other types of process o method of treating plants and animals (and even human: are, in principle, patentable, but there is a specific exclusion of methods practised on the human or animal body for surgical, therapeutic or diagnostic purposes. (Apparatus for use in such methods will, however, continue to be patentable.) The precise extent of the restrictions on the European patent law patentability of this type of invention will need to be We have referred so far mainly to the changes in British explored in practice and a case law developed. patent law, but it must be remembered that these arise from the desire and need to bring our national law into harmony with developments in the patent law throughout Europe. This brings us immediately to a consideration of United States patent law the new European patent law covered by the European Patent Convention. Of the 16 States which have signed The US patent system has many highly attractive feature! this Convention so far, UK, Netherlands, West Germany, and in the technological literature of that country mort
ion it was not required to present the patent claims, i.e. he definitions of the features of the invention for which irotection is sought; it was enough to describe the invenion sufficiently well to establish that the inventive concept xisted and could be formulated explicitly at an early late, a fact of importance whenever it came to a dispute wer priority between two or more parties claiming the ame idea. Some practical demonstration of the concept vas usually very desirable at this stage, but a further beriod of one year was allowed for presenting the complete pecification which would include the claims and which vould be the definitive document to be examined by the ’atent Office. This system had certain advantages for the tpplicant. First, it allowed for developments arising within he year following the provisional specification to be in:luded in the completc specification and, up to a point, t permitted some rethinking of the original presentation. rhis was a very convenient element of flexibility where the :ssentials of the invention were not clear-cut at the prorisional stage, for in such cases it was possible in the irovisional to foreshadow alternatives and a possible shift if emphasis as regards the crux of the invention after a ireliminary study of previously published work. This ’acility was subject, however, to the check and balance :hat any claims made which were not “fairly based” on the yovisional disclosure were not entitled to the priority date sf the provisional but only that of the complete specifi:ation. The provisional/complete specification system aperates in the UK and Commonwealth and is generally appreciated by inventors resident in these territories. How:ver, in continental Europe, the United States, Japan and indeed virtually everywhere else, an inventor was, in fact, obliged to file the equivalent of our complete specification in the first instance, there being no such thing as the provisional in their own national law. Inevitably, the tendency would be for the non-British inventor to delay filing his application for patent protection until he was in the position to draft an effective specification having claims well supported by the data and the degree of disclosure required. The new British law will do away with the provisional and complete specifications as such, although it will replace them by something rather similar. Thus, it will be possible to interrelate for priority claiming purposes two separate patent applications if they are dated within one year of each other. Furthermore, it will be possible to file what we should now perhaps call a n informal specification, i.e. without claims, and supply these claims within a prescribed period. Although this sounds rather like the provisional specification in another guise, there will be some important legs1 distinctions to make between the two and at the present time patent specialists studying the new Bill are attempting to assess the practical effects of the change. One conclusion seems to be emerging fimly, namely, that the whole discipline of patenting will be tighter in future. It will certainly be necessary to construct a patent situation on a proper foundation from the start, and it will no longer be so easy to bolster up an initially weak disclosure and weak application generally by the filing of further data and further applications at a later stage.
September, 1977
26 1
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tribute seems to be paid to it, as an ingredient of national progress, than is accorded by writers in other countries to their own systems. In regard to publication, a US inventor does not scuttle himself by publication first provided he files his patent application within one year of publication. This is admirable if he is concerned only with protecting his home market, but it can be a snare if he has wider horizons for the exp!citztion ef his inuentlcrn and is unaware of the foreign law with its absolute novelty requirement. Canada, incidentally, is even more generous in providing a two year period of grace. Again, when there is a conflict between two parties claiming the same invention US law does not solve the dispute on a first-to-file basis but has a very complex way of determining priority which is the domain of highly specialist expertise and justifies a textbook to itself. Indeed, US patent law and practice as a whole is probably a more elaborate construction of the human mind than any other patent system and has a richly developed case law. One of the snags to this is the problem 3f keeping up with it and charting a course through it. On the debit side I would have to mention the rather ubitrary approach of the US Patent Office Examiner who seems much less controlled by case law than his counter3arts elsewhere and often makes the applicant fight costly 3attles because the Examiner refuses to follow a particular xecedent decision. Whilst on this side of the account I ivould also mention an attitude, not restricted to US Examiners of course, but one in which they excel, of ndiscriminately giving the prior art much more weight han it really has. Inventors know only too well that a yeat proportion of the literature is of little significance ind they will often be astonished at the argumentation :onstructed by an Examiner and his assessment of what L particular prior paper or patent would teach a worker )f ordinary skill towards the solution of the inventor's )wn particular problem. Unfortunately Examiners are LOW under direction to demand even higher standards of nventiveness before allowing the applicant's claim. In eal life inventions are made by ordinary human beings ,nd not supermen, and technological innovation is not ostered on a broad front by restricting patents to the Jobel prize winners of this world. However, when you lo succeed in the argument with the Examiner and the latent is granted, its lifespan runs from grant without urther cost and this is a good feature for the patentee. n most other countries the term is calculated from appliation date and sometimes a goodly proportion of this eriod is taken up in the struggle to obtain the patent. mother valuable facet of US patenting is the facility to uild upon the original application by means of so-called ontinuation-in-part applications in which later developients can also be protected and, if desired, a whole series f applications can be subsumed into one omnibus patent. 'his is obviously an advantageous feature in a field of ipidly developing technology and is much superior to a {stem in which so much depends on being able to draft well documented and comprehensive specification at the rst shot. To conclude on a practical note let us consider how to andle a given situation. The complexity of the patent eld and the developing law and practice will make it more scessary than ever to seek professional help as opposed ) the do-it-yourself approach. The process should begin ith a disclosure to the patent adviser of one's choice in etailed written form and preferably, in addition, by robing discussions between inventor and patent agent. ommunication can be a difficulty here and the inventor iould understand that his agent can only try to protect 1 invention according to the understanding of it that the iventor has managed to convey to him. It is sometimes fficult for someone who is deep in the knowledge of his 262
subject to realise that his listener has to deal with a wid range of inventions and therefore cannot have specialit knowledge in more than a few disciplines. The object c the discussion is to assess the experimental data and forr a view of the scope of patent claims that should be prf sented, and it is therefore very desirable that the state a prior knowledge is properly taken into account in framin the verbal definitions. These must be neither too broad t stand a chance of acceptance by the Patent Office becaus they impinge on the prior art, nor too narrow to alloi loopholes for others to enter the field with perhaps some thing only slightly inferior yet which really borrows fron the inventor's work. I have mentioned above the possible view that all thi effort may be considered by some not to be worthwhill and I would say to inventors of this persuasion that, unles they have some motivation to see their research appliec to a practical purpose with an economic dimension, t h a it is better to stay out and avoid the frustrations. To thosc who are interested I would offer the consolation that thc patent agent will usually shield them from much of thc tedious negotiation with Patent Office Examiners which i, necessary to Secure the desired scope of patent cover ir the face of official objections. One has to admit also tha the problems do not end there for even when the paten rights are granted they have to be exploited and this call: for yet another kind of expertise which can perhaps best be described as entrepreneurial. The patent agent as suck is often not geared up to undertake this activity to the full being himself primarily concerned with providing a pro. fessional service for the obtaining of patents, although hf will often be able to participate effectively in licence nego. tiations and help his client to avoid pitfalls even in purel) business decisions. The need for licensing has called into being another kind of professional skill which though no1 yet formalised into a recognised professional body is nevertheless very demanding. Licensing has long been under the shadow of the anti-trust laws of the United States and their equivalent in the European Economic Community in which the Brussels Commission has assumed the role of guardian of the maintenance of free undistorted competition and the free flow of goods across national frontiers in the EEC. What can or cannot be done legally in the licensing field is now a complex matter and the subject of a developing framework of European Court decisions and Commission regulations and guide-lines. Inventors will continue to invent, whether patents and licensing laws exist or not, for curiosity is built into their nature but the extent to which their ideas are taken up in the face of the frequently high risks of technical or commercial failure probably depends on the availability of some system of security such as the patent law offers. Inventors are well advised to seek the help of those who know how to make this system deliver results.
Copyright Finally, as increasing attention is currently being given to the degree of protection afforded by the Copyright and Design laws, it would be useful to note these two other related forms of intellectual property, and distinguish them from patent protection. The patent aims to cover the underlying principle or idea behind an invention so as to protect all forms and practical embodiments of it in as many variations as can possibly be achieved. This is the function of the patent claims. Registered designs are concerned with features of shape, configuration, pattern or ornament which appeal to and are judged solely by the eye. Compared to patents the registered design gives relatively narrow protection and is easily avoided by making] Journal of Medical Engineering and Technology
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an article look different. Copyright is different again. There is no copyright in ideas but only in the form or expression of an idea. Furthermore, whereas patents and registered designs are rights granted on a monopoly basis, and therefore cover not only direct imitation and piracy but also independent research, copyright requires actual copying before infringement can be held to have occurred, and it is a defence in a copyright action to prove independent origin of the design. Copyright is based on the concept of an artistic work and a great part of the law is of course concerned with works of a literary or other culturally artistic nature. However, it is well established that engineering drawings are artistic works within the meaning of the Act irrespective of their artistic merit. Some articles start their life not in the form of drawings but as models or prototypes and these are more difficult to bring within the present copyright law unless they are works of artistic craftsmanship. The Courts have found great difficulty in defining
what is meant by a work of artistic crafsmanship and therefore if one is seeking to rely on copyright protection the author of a design should always be careful to make and retain an original drawing. Copyright arises spontaneously when the original work is created and no registration system is required. Therefore some workers might be tempted to rely on copyright protection and to avoid the more complicated procedure of obtaining patent protection. This is a tenable position provided its limitations are fully realised. There certainly seems to be strong sympathy for the copyright owner in Court decisions at the present time provided, as indicated above, the Court is convinced that there has been copying. It cannot be too strongly emphasised, however, that this form of protection cannot stop a third party taking what appears to be the fundamental idea in the inventor’s system and modifying it, embellishing it and making improvements on it, unless it is clear that the essential form of expression of this idea is retained and copyright attaches to it.
A technique for the non-invasive estimation of cerebral blood flow in the newborn infant R. W. I. C o d e MBBS, MRCP, DCH P. Rolfe BSc., PhD., C.Eng., M.I.E.E. and P. Howat RGN, SCM Bioengineering Unit, University Department of Paediatrics, John Radclifle Hospital, Headington, Oxford, U K .
In the newborn infant, the cerebral oirculation comprises about one-#third of the total cardiac output. Diseases of the cardiorespiratory system which are common in the first few weeks of life will almost ineviltably affect the blood flow to the brain. Cerebral hypoxia, whether due to pulmonary disease, recurrent apnoea, or birth asphyxia, is likely to cause derangements of cerebral circulation, and has been implicated in intracranial haemorrhage of the newborn,l-* and in cerebral palsy.4 Intracranial haemorrhage is now a major sause of death in very low birth weight infants. Investigation of the way in which the cerebral circulation responds in rhese circumstances is therefore of importance in understanding the pathophysiology of these diseases. Although accurate measurement of cerebral blood flow has only recently been possible, an awareness of its importance has existed for centuries. Even before Willis described the anatomy of the cerebral blood supply, and Harvey the circulation of the blood, it was appreciated that the brain pulsated, and that these pulsations were arterial in origin.& Early attempts were made in the nineteenth century to estimate changes in cerebral blood flow by recording cerebral pulsations through skull defects in mane and in dogs.? It was a further sixty-five years before the first reliable measurement of cerebral blood flow in man was made by Kety and Schmidt* in 1948, using a nitrous oxide washout technique. Many variants of this technique have appeared since then, mostly using radioactive tracers ~ injection of 133 Xenon such as 85 K r y p t ~ n .Intramrotid with gamma radiation counting through the intact skull has been used, mainly in Scandinavia, and has allowed accurate estimates of regional cerebral blood flow variation to be made.10 Non-invasive methods for the measurement of cerebral blood flow have been mainly based on the use of electrical impedance variations of the head, and the use of Doppler ultrasound technliqum to measure carotid artery blood veloSeptember, 1977
city. Most attempts to use electrical impedance mwDhods have been unsuccessful, and poor correlation between impedance measurements and carotid flow meter measurements have been shown in animal studies.11 This may be due to lack of current m a t r a t i o n of the skull, as bone has a relatively high resistivity. Ultrasound techniques suffer from the problem that velocity flow can only be converted to volumetric flow if continuous information about vessel size, b m / v e s w l angle, and velocity profiles is available throughout the cardiac cycle. Although a few attempts have been made to measure cerebral blood flow in the newborn period using nitrous oxide12 or radioisotopic techniques,lszl* the need for arterial and jugular vein samples, and the use of radioisotopes, make the methods ethically unacceptable in this country today, particularly in the research field. In the USSR electrical impedance measurements have been used to obtain qualitative informaition on changes in cerebral blood flow in infanct during the newborn period.l6 Changes over rhe first few days of life and following birth asphyxia were reported.Ic Measurement of small variations in ear or fontanelle temperatures have been used as a qualitative thermal clearance technique, and increases in temperature following feeding interpreted as a fall in cerebral blood flow.173 Development of the technique described in this paper has btxn prompted by the need for a method which is both non-invasive yet quantitafive, and suitable for use in the newborn infant.
Method Recently, venous occlusion plethysmography has been described for the estimation of changes in cerebral blood flow in the newborn infant.19 This technique is possible because the bones of the newborn infant’s skull are not fused at birth, and the skull is thus able to transmit cetebra1 arterial pulsations. If a mercury-in-rubber strain gauge20 is placed around the infant’s occipitofrontal head 263
ISSN: 0309-1902 (Print) 1464-522X (Online) Journal homepage: http://www.tandfonline.com/loi/ijmt20
A practical approach to patenting R. S. Crespi To cite this article: R. S. Crespi (1977) A practical approach to patenting, Journal of Medical Engineering & Technology, 1:5, 259-263, DOI: 10.3109/03091907709162190 To link to this article: http://dx.doi.org/10.3109/03091907709162190
Published online: 09 Jul 2009.
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18. Judet, J., Judet, R., Lagrange, J. and Dunoyer, J. Resection reconstruction of the hip. Arthroplasty with acrylic proathesis. (Livingstone, Edinburgh & London, 1954). 19. Charnley, J. (1967). Fractors in the Design of an Artificial Hip Joint. Proceedings, Institution of Mechanical Engineers, 181 (3J) 104-111. 20. Weber, B. G., Stiihmer, G. and Semlitsch, M. (1974).
Erfahrungen mit dem Kunststoff Polyester als Komponente der Rotationstotalprothese des Huftgelenkes. (Experience with poly-ester as a component of the rotation total prosthesis for the hip-joint). Zeitschrift fur Orthopadie und ihre Grenzgebiete, 112 ( 5 ) 1106-1112.
21. Sundal, B., Kavlie, H. and Christiansen, T. (1974). Total
hip replacement with a new frunnion-bearing prosthesis (the Christiansen prosthesis). Acta Chirurgica Scan-
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dinavica, 140 (3) 189-193. 22. Schmittgmnd, G. D., Kenner, G. H. and Brown, S . D. (1973). In vivo and in vitro changes in strength of orthopaedic calcium aluminates. Journal of Biomedical Materials Research, Symposium No. 4, 435. 23. Boutin, P. (1972). Arthroplastie total de la hanche par
24. Geduldig, D., Lade, R., Prlissner, P., Willert, H-G., Zichner, L. and Doerre, E. Experimental Investigations
of dense Alumina Ceramic for Hip and Knee Joint Replacements. In Advances in Artificial Hip and Knee Joint Technology, ed. M. Schaldach and D. Hohmann, pp. 434445 (Springer, Berlin, 1976). 25. Griss, P., Krempien, B., v. Andrian-Werburg, H., Heimke, G. and Fleiner, R. (1 973). Experimentelle Untersuchung zur Gwebsvertraglichkeit oxidkeramischer (A12 0 3 ) Abriebteilchen. Archiv f u r orthopadische urld Unfall-Chirurgie, 76. 270-279. 26. Griss, P., Heimke, G., Krempien, B. and Jentschura, J.
Ceramic Hip Joint Replacement-Experimental Results and Early Clinical Experience. In ‘Advances in Artificial Hip and Knee Joint Technology’ ed. M. Schaldach and D. Hohmann, page 446 (Springer, Berlin, 1976). 27. Boutin, P. (1974). Les prostheses totales de la hanche en alumine. L‘ancrage direct sans ciment dans 50 cas. (Total hip prosthesis made of dense ceramics (Fritted alumina). A Study of the attachment to bone.) Revue de Chirurgie Orthopidique et Reparatrice de I‘dppareil Moteur, 60 (3) 233-245.
prosthese en alumine fritb. (Total hip arthroplasty made of dense ceramics (fritted alumina)). Revue de Chirurgie Othopkdique et Reparatrice de I‘Appareil Moteur, 58 (3) 229.
A practical approach to patenting R. S. Crespi National Research Development Corporation, PO Box 236, Kingsgate House, 6 6 / 6 7 Victoria Street, London S W l E 6SL, U K .
This article is intended to draw attention to some of the pitfalls which await the unwary inventor in the fields of biology and medical science should he wish to patent his new invention. Aspects of British, United State3 and European patent lm are outlined and practical aspects of making a patent application ure discussed. The article concludes with a short note on copyright. There appears to be a wave of interest at the present time in the subject of patents and articles are appearing on a variety of aspects of the patent law from particular standpoints. The justification for yet another contribution on this topic must be the fact that the patent laws are in a period of change and the opportunity is a good one, therefore, to present an account which is both an introduction for the benefit of those who are newcomers to patent matters and a refresher for those who have some working knowledge of it already. Many scientific workers are brought up in the philosophy of research and publication with the result that, when one believes he has produced some new finding of’ interest to the scientific community, the first impulse is to let the, world know about it as soon as possible. This excellent maxim may, however, need some qualification because the published information can often be capable of practical exploitation for commercial ends as well as enriching the state of scientific knowledge. I n these circumstances there is no reason why the person who generates an innovation of this kind should not benefit from it by recognition in both fields of human activity. Industrial research workers are, of course, orientated towards the practical purposes of their research for the benefit of their employer and, being already converted, they are in no need of any message. Other kinds of researcher who d o not have industrial backing may take the view that commercial exploitation of their research is too uncertain, tedious, and generally not suited to their talents, and in the majority of cases they are probably right. On the other hand, if they take the precaution of protecting themselves by the filing of a patent application September, 1977
before publishing any results which strike them as having potential practical significance for industry, there is a reasonable chance that some share in the commercial development may be possible for them by association with it technically or financially by means of a modest royalty on use of the invention. The same precaution applies where the new process or device is to be put into use or subjected to clinical trial in a public manner. The steps necessary for the protection of an invention by means of a patent are generally well known in outline. Thus, if the particular finding is novel and amounts to a sufficiently significant advance upon previous knowledge, and offers the prospect of being of practical value in an industrial context, the process of protecting the invention begins with the filing of an application at the Patent Office before it is in any way publicised or put into public use. 1 have used the term “finding” at this stage to cover generally the kinds of subject matter that can be patented. We can briefly enumerate the various categories as processes, products (and articles), apparatus (and devices), methods of treatment and methods of testing. However, we should note that not all of these items can be patented to the same extent in every country, and the whole subject has its share of ifs and buts under each heading. I do not propose to offer a n exhaustive definition of each category of patentable invention, but some indication of the sorts of things we are concerned with must be given. By “processes” we mean manipulation of some material by mechanical, electrical, chemical or any other procedure for an economic purpose and, usually, to give rise to a vendible product. “Product” can mean any article or material (including a pure substance and a chemical 259
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composition) resulting from some process of assembly, preparation, or extraction. Apparatus carries its ordinary and very general connotation, including any form of equipment or gadgetry. Methods of treatment are, strictly speaking, included under the heading of processes, although in many cases it seems more appropriate to use method terminology, especially where the substrate acted upon is living, for example plants or animals. To be pateiitable the paiiiciilai finding must be new, inventive and useful in some way, and these three requirements are the criteria of patentability in most systems of patent law yet devised. In principle I suppose few would quarrel with the idea that a patent monopoly should only be granted to someone if his contribution is really new and ingenious and lies at least a little way outside the normal track of the day to day routine activities of scientific workers. The difficulty lies in the application of this test in the absence of any clear method of quantifying the conception of what constitutes invention. To make matters worse, the Patent Office Examiner, who is the person we have to convince that an invention has been made, is entitled and indeed required to judge what is offered to him against the background of all previously recorded knowledge, this being referred to by the now universally used term “the prior art”. In general the prior art includes everything on publicly available record or in public use before the inventor’s patent application is filed (the .US patent system has a more sophisticated approach to this question which I will mention later). All prior published documents are citable by the Examiner irrespective of whether they are scientifically well founded or mere paper proposals or even mere science fiction. The Examiner is apt to combine bits from separate documents and make up an artificial construction or “mosaic” in order to argue that the inventor’s contribution lacks the requisite degree of novelty or inventiveness. Inventors do not always realise that the widely enibracing extent of the prior art also jncludes all that they have themselves published or put to use in a public manner. Some tend to regard it as harsh and unfair that the law makes no exception in respect of their own publications. For inventors who regularly publish their work, therefore, a matter of major importance must be faced at the outset, namely, the relationship between patenting policy and u policy of rapid publication and the extent to which the one places inhibitions on the other. In fact this problem can easily be overestimated, and one often finds that it diminishes when examined coolly and with patience and a willingness to seek a compromise solution. There is an important difference between European and United States patent law on this topic, and therefore it would be prefer3ble to look further at this particular problem in the zontext of a brief review of some of the separate patent legal systems, and to these we now turn.
British patent law The present British patent law is covered basically by the 1949 Patents Act, but there is to be a 1977 Patents Act which will come into force probably early in 1978, so that Ne can now begin to speak of the old law and the new aw. Dealing first with the publication conflict mentioned ibove, one helpful factor in the past has been the xivileged position of certain journals of and meetings held by Learned Societies which have been exempted from the general rule that publication prior to filing a patent ipplication automatically deprives the patent of validity. rhis provision has been particularly attractive to academic research workers and has sometimes been believed to be wider in scope that it really is. The Learned Society 260
provision is of restricted territorial application, but it has often been grasped as the only lifeline to save at least the UK patent position. A change of major importance in the new British law is that publication at Learned Society meetings, or in the journals of such societies, will no longer have the protected status enjoyed in the past and will be treated as part of the so-called “prior art”. Consequently if patent protection is not sought before publication of this kind occiirs the chances of securing protection later are diminished to the extent that t h e publication reveals the essentials of the invention and enables the skilled reader to put it into practice, or renders it obvious. A t this point it would be desirable to note that publication in the legal sense also includes disclosures in theses in libraries, talks and demonstrations on Open Days, colloquia, lectures and any other way of making the invention available to the public. Related to the Learned Society provision is one which at present applies to certain types of exhibition at which display of the invention, usually an item of equipment, is protected. The new version of this provision involves a considerable restriction of the privilege, and inventors who are accustomed to participate at such exhibitions should check their position carefully in future. It is important to be clear about the question of clinical trials and, following on from this, the extent to which an invention may be put into use after the trial period without jeopardising the patent position. Reasonable trial and experimental testing of a drug or device do not in themselves constitute a prior use which would prejudice a later-filed patent application, but the problem is that it is often difficult to arrange such trials without a certain amount of leakage of information and even publicity, with the result that the invention is effectively pre-disclosed before anyone has thought about the question of patent protection; and by then it is often too late. Many inventors are unaware of this and will often launch their eventual patenting attempt on the basis that the device has been successfully used quite openly by doctors and nurses for a considerable period of time. I n some cases, of course. practical trials have to take place in a public manner, and the old law catered for that by allowing a period of one year for public working in this special category of invention before the patent application was filed. The new law is not explicit on this topic and, until one knows how these matters will be interpreted, it will be advisable to exercise caution. Under the old law any use of an invention, after the trial period, would invalidate a patent based on a laterfiled application because it would be either a prior public use o r a prior secret use and both these were grounds of invalidating and hence of revocation of the patent. Consequently it was necessary to make up one’s mind about the question of patents before the method or device was put into routine use, and it probably made little real difference whether the intended use was commercial or not and whether it could be carried out without the knowledge of it coming into the possession of the public. The new law is possibly less clear on this point because, for the purpose of refusing a patent application o r of invalidating a patent, the anticipatory use must be a matter which has been made available to the public. Thus, if the invention is an item of equipment for use in a laboratory to which the public do not normally have access, for example a hospital laboratory, one has to ask whether it is available; possibly it can be said to be available to the public in the sense that the use has been carried out for the benefit of patients, even though they did not know precisely what method or device was in fact used. Formerly it was possible to initiate patent action by presenting to the Patent Office a specification of the invention in a provisional manner. In the provisional specificaJournal of Medical Engineering and Technology
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Luxembourg, Switzerland and France have ratified it, enabling the Convention to enter into force next month, although the European Patent Office will probably not open for business until the summer of 1978. Anyone seeking patent protection in the relevant states or a designated number of them can proceed by means of a single patent application in the European Patent Office which, if successful, will result in the grant of a bundle of separate patents for the designated states. In this Convention we have not yet reached the concept of a single unitary patent for the aggregate territories of the various states but some years ahead of us there lies such a goal in the form of the Community Patent System (dealt with in the Community Patent Convention) covering the EEC as a whole. The European Patent Convention is in fact a body of substantive patent law, and regulations which will control the procedure of obtaining protection in the states which the applicant has designated. The general character of this law, for example, its rules governing patentability. is nou becoming the norm to which many European states art conforming their own individual strictly national paten1 laws. It is important to realise that the latter will continut to exist as separate systems and patenting routes alongsidt the European system and to some extent perhaps competi tive with it as regards cost. The following remarks on patentability apply both tc national and European laws. As to the general character of the new laws and thc type of subject matter that can be patented, engineers an( physicists will find little change from past practice. Thc list of exclusions from patentability in the European lav includes discoveries, aesthetic creations, schemes, rules an( methods for performing mental acts, computer program and presentations of information, but this negativc approach is already familiar to inventors in these fields Professional advice should however always be sough before ruling out possibilities in this area. The impact of European law is much greater in thi chemical and biological fields. For the chemist, produc patents for new substances will continue in UK and wil now also be obtainable in Europe as well as the type o process patent which has been the more usual form o protection allowed previously under national laws of mos European states. New uses of old substances will also b patentable in a restricted way. In the biological field, th patentability of substances or devices is in conformity wit1 what has been stated above. As to processes, however, th question is more complex. “Essentially biological” pro cesses for the production of plants or animals are unpatenl able but the interpretation of this phrase is not clear-cul It seems to suggest absence of technical interventior Patents for microbiological processes and products ar specifically allowable. Where a new strain of micrc organism is involved, it must be deposited in an officiz culture collection and made publicly available when th specification is first published. Other types of process o method of treating plants and animals (and even human: are, in principle, patentable, but there is a specific exclusion of methods practised on the human or animal body for surgical, therapeutic or diagnostic purposes. (Apparatus for use in such methods will, however, continue to be patentable.) The precise extent of the restrictions on the European patent law patentability of this type of invention will need to be We have referred so far mainly to the changes in British explored in practice and a case law developed. patent law, but it must be remembered that these arise from the desire and need to bring our national law into harmony with developments in the patent law throughout Europe. This brings us immediately to a consideration of United States patent law the new European patent law covered by the European Patent Convention. Of the 16 States which have signed The US patent system has many highly attractive feature! this Convention so far, UK, Netherlands, West Germany, and in the technological literature of that country mort
ion it was not required to present the patent claims, i.e. he definitions of the features of the invention for which irotection is sought; it was enough to describe the invenion sufficiently well to establish that the inventive concept xisted and could be formulated explicitly at an early late, a fact of importance whenever it came to a dispute wer priority between two or more parties claiming the ame idea. Some practical demonstration of the concept vas usually very desirable at this stage, but a further beriod of one year was allowed for presenting the complete pecification which would include the claims and which vould be the definitive document to be examined by the ’atent Office. This system had certain advantages for the tpplicant. First, it allowed for developments arising within he year following the provisional specification to be in:luded in the completc specification and, up to a point, t permitted some rethinking of the original presentation. rhis was a very convenient element of flexibility where the :ssentials of the invention were not clear-cut at the prorisional stage, for in such cases it was possible in the irovisional to foreshadow alternatives and a possible shift if emphasis as regards the crux of the invention after a ireliminary study of previously published work. This ’acility was subject, however, to the check and balance :hat any claims made which were not “fairly based” on the yovisional disclosure were not entitled to the priority date sf the provisional but only that of the complete specifi:ation. The provisional/complete specification system aperates in the UK and Commonwealth and is generally appreciated by inventors resident in these territories. How:ver, in continental Europe, the United States, Japan and indeed virtually everywhere else, an inventor was, in fact, obliged to file the equivalent of our complete specification in the first instance, there being no such thing as the provisional in their own national law. Inevitably, the tendency would be for the non-British inventor to delay filing his application for patent protection until he was in the position to draft an effective specification having claims well supported by the data and the degree of disclosure required. The new British law will do away with the provisional and complete specifications as such, although it will replace them by something rather similar. Thus, it will be possible to interrelate for priority claiming purposes two separate patent applications if they are dated within one year of each other. Furthermore, it will be possible to file what we should now perhaps call a n informal specification, i.e. without claims, and supply these claims within a prescribed period. Although this sounds rather like the provisional specification in another guise, there will be some important legs1 distinctions to make between the two and at the present time patent specialists studying the new Bill are attempting to assess the practical effects of the change. One conclusion seems to be emerging fimly, namely, that the whole discipline of patenting will be tighter in future. It will certainly be necessary to construct a patent situation on a proper foundation from the start, and it will no longer be so easy to bolster up an initially weak disclosure and weak application generally by the filing of further data and further applications at a later stage.
September, 1977
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tribute seems to be paid to it, as an ingredient of national progress, than is accorded by writers in other countries to their own systems. In regard to publication, a US inventor does not scuttle himself by publication first provided he files his patent application within one year of publication. This is admirable if he is concerned only with protecting his home market, but it can be a snare if he has wider horizons for the exp!citztion ef his inuentlcrn and is unaware of the foreign law with its absolute novelty requirement. Canada, incidentally, is even more generous in providing a two year period of grace. Again, when there is a conflict between two parties claiming the same invention US law does not solve the dispute on a first-to-file basis but has a very complex way of determining priority which is the domain of highly specialist expertise and justifies a textbook to itself. Indeed, US patent law and practice as a whole is probably a more elaborate construction of the human mind than any other patent system and has a richly developed case law. One of the snags to this is the problem 3f keeping up with it and charting a course through it. On the debit side I would have to mention the rather ubitrary approach of the US Patent Office Examiner who seems much less controlled by case law than his counter3arts elsewhere and often makes the applicant fight costly 3attles because the Examiner refuses to follow a particular xecedent decision. Whilst on this side of the account I ivould also mention an attitude, not restricted to US Examiners of course, but one in which they excel, of ndiscriminately giving the prior art much more weight han it really has. Inventors know only too well that a yeat proportion of the literature is of little significance ind they will often be astonished at the argumentation :onstructed by an Examiner and his assessment of what L particular prior paper or patent would teach a worker )f ordinary skill towards the solution of the inventor's )wn particular problem. Unfortunately Examiners are LOW under direction to demand even higher standards of nventiveness before allowing the applicant's claim. In eal life inventions are made by ordinary human beings ,nd not supermen, and technological innovation is not ostered on a broad front by restricting patents to the Jobel prize winners of this world. However, when you lo succeed in the argument with the Examiner and the latent is granted, its lifespan runs from grant without urther cost and this is a good feature for the patentee. n most other countries the term is calculated from appliation date and sometimes a goodly proportion of this eriod is taken up in the struggle to obtain the patent. mother valuable facet of US patenting is the facility to uild upon the original application by means of so-called ontinuation-in-part applications in which later developients can also be protected and, if desired, a whole series f applications can be subsumed into one omnibus patent. 'his is obviously an advantageous feature in a field of ipidly developing technology and is much superior to a {stem in which so much depends on being able to draft well documented and comprehensive specification at the rst shot. To conclude on a practical note let us consider how to andle a given situation. The complexity of the patent eld and the developing law and practice will make it more scessary than ever to seek professional help as opposed ) the do-it-yourself approach. The process should begin ith a disclosure to the patent adviser of one's choice in etailed written form and preferably, in addition, by robing discussions between inventor and patent agent. ommunication can be a difficulty here and the inventor iould understand that his agent can only try to protect 1 invention according to the understanding of it that the iventor has managed to convey to him. It is sometimes fficult for someone who is deep in the knowledge of his 262
subject to realise that his listener has to deal with a wid range of inventions and therefore cannot have specialit knowledge in more than a few disciplines. The object c the discussion is to assess the experimental data and forr a view of the scope of patent claims that should be prf sented, and it is therefore very desirable that the state a prior knowledge is properly taken into account in framin the verbal definitions. These must be neither too broad t stand a chance of acceptance by the Patent Office becaus they impinge on the prior art, nor too narrow to alloi loopholes for others to enter the field with perhaps some thing only slightly inferior yet which really borrows fron the inventor's work. I have mentioned above the possible view that all thi effort may be considered by some not to be worthwhill and I would say to inventors of this persuasion that, unles they have some motivation to see their research appliec to a practical purpose with an economic dimension, t h a it is better to stay out and avoid the frustrations. To thosc who are interested I would offer the consolation that thc patent agent will usually shield them from much of thc tedious negotiation with Patent Office Examiners which i, necessary to Secure the desired scope of patent cover ir the face of official objections. One has to admit also tha the problems do not end there for even when the paten rights are granted they have to be exploited and this call: for yet another kind of expertise which can perhaps best be described as entrepreneurial. The patent agent as suck is often not geared up to undertake this activity to the full being himself primarily concerned with providing a pro. fessional service for the obtaining of patents, although hf will often be able to participate effectively in licence nego. tiations and help his client to avoid pitfalls even in purel) business decisions. The need for licensing has called into being another kind of professional skill which though no1 yet formalised into a recognised professional body is nevertheless very demanding. Licensing has long been under the shadow of the anti-trust laws of the United States and their equivalent in the European Economic Community in which the Brussels Commission has assumed the role of guardian of the maintenance of free undistorted competition and the free flow of goods across national frontiers in the EEC. What can or cannot be done legally in the licensing field is now a complex matter and the subject of a developing framework of European Court decisions and Commission regulations and guide-lines. Inventors will continue to invent, whether patents and licensing laws exist or not, for curiosity is built into their nature but the extent to which their ideas are taken up in the face of the frequently high risks of technical or commercial failure probably depends on the availability of some system of security such as the patent law offers. Inventors are well advised to seek the help of those who know how to make this system deliver results.
Copyright Finally, as increasing attention is currently being given to the degree of protection afforded by the Copyright and Design laws, it would be useful to note these two other related forms of intellectual property, and distinguish them from patent protection. The patent aims to cover the underlying principle or idea behind an invention so as to protect all forms and practical embodiments of it in as many variations as can possibly be achieved. This is the function of the patent claims. Registered designs are concerned with features of shape, configuration, pattern or ornament which appeal to and are judged solely by the eye. Compared to patents the registered design gives relatively narrow protection and is easily avoided by making] Journal of Medical Engineering and Technology
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an article look different. Copyright is different again. There is no copyright in ideas but only in the form or expression of an idea. Furthermore, whereas patents and registered designs are rights granted on a monopoly basis, and therefore cover not only direct imitation and piracy but also independent research, copyright requires actual copying before infringement can be held to have occurred, and it is a defence in a copyright action to prove independent origin of the design. Copyright is based on the concept of an artistic work and a great part of the law is of course concerned with works of a literary or other culturally artistic nature. However, it is well established that engineering drawings are artistic works within the meaning of the Act irrespective of their artistic merit. Some articles start their life not in the form of drawings but as models or prototypes and these are more difficult to bring within the present copyright law unless they are works of artistic craftsmanship. The Courts have found great difficulty in defining
what is meant by a work of artistic crafsmanship and therefore if one is seeking to rely on copyright protection the author of a design should always be careful to make and retain an original drawing. Copyright arises spontaneously when the original work is created and no registration system is required. Therefore some workers might be tempted to rely on copyright protection and to avoid the more complicated procedure of obtaining patent protection. This is a tenable position provided its limitations are fully realised. There certainly seems to be strong sympathy for the copyright owner in Court decisions at the present time provided, as indicated above, the Court is convinced that there has been copying. It cannot be too strongly emphasised, however, that this form of protection cannot stop a third party taking what appears to be the fundamental idea in the inventor’s system and modifying it, embellishing it and making improvements on it, unless it is clear that the essential form of expression of this idea is retained and copyright attaches to it.
A technique for the non-invasive estimation of cerebral blood flow in the newborn infant R. W. I. C o d e MBBS, MRCP, DCH P. Rolfe BSc., PhD., C.Eng., M.I.E.E. and P. Howat RGN, SCM Bioengineering Unit, University Department of Paediatrics, John Radclifle Hospital, Headington, Oxford, U K .
In the newborn infant, the cerebral oirculation comprises about one-#third of the total cardiac output. Diseases of the cardiorespiratory system which are common in the first few weeks of life will almost ineviltably affect the blood flow to the brain. Cerebral hypoxia, whether due to pulmonary disease, recurrent apnoea, or birth asphyxia, is likely to cause derangements of cerebral circulation, and has been implicated in intracranial haemorrhage of the newborn,l-* and in cerebral palsy.4 Intracranial haemorrhage is now a major sause of death in very low birth weight infants. Investigation of the way in which the cerebral circulation responds in rhese circumstances is therefore of importance in understanding the pathophysiology of these diseases. Although accurate measurement of cerebral blood flow has only recently been possible, an awareness of its importance has existed for centuries. Even before Willis described the anatomy of the cerebral blood supply, and Harvey the circulation of the blood, it was appreciated that the brain pulsated, and that these pulsations were arterial in origin.& Early attempts were made in the nineteenth century to estimate changes in cerebral blood flow by recording cerebral pulsations through skull defects in mane and in dogs.? It was a further sixty-five years before the first reliable measurement of cerebral blood flow in man was made by Kety and Schmidt* in 1948, using a nitrous oxide washout technique. Many variants of this technique have appeared since then, mostly using radioactive tracers ~ injection of 133 Xenon such as 85 K r y p t ~ n .Intramrotid with gamma radiation counting through the intact skull has been used, mainly in Scandinavia, and has allowed accurate estimates of regional cerebral blood flow variation to be made.10 Non-invasive methods for the measurement of cerebral blood flow have been mainly based on the use of electrical impedance variations of the head, and the use of Doppler ultrasound technliqum to measure carotid artery blood veloSeptember, 1977
city. Most attempts to use electrical impedance mwDhods have been unsuccessful, and poor correlation between impedance measurements and carotid flow meter measurements have been shown in animal studies.11 This may be due to lack of current m a t r a t i o n of the skull, as bone has a relatively high resistivity. Ultrasound techniques suffer from the problem that velocity flow can only be converted to volumetric flow if continuous information about vessel size, b m / v e s w l angle, and velocity profiles is available throughout the cardiac cycle. Although a few attempts have been made to measure cerebral blood flow in the newborn period using nitrous oxide12 or radioisotopic techniques,lszl* the need for arterial and jugular vein samples, and the use of radioisotopes, make the methods ethically unacceptable in this country today, particularly in the research field. In the USSR electrical impedance measurements have been used to obtain qualitative informaition on changes in cerebral blood flow in infanct during the newborn period.l6 Changes over rhe first few days of life and following birth asphyxia were reported.Ic Measurement of small variations in ear or fontanelle temperatures have been used as a qualitative thermal clearance technique, and increases in temperature following feeding interpreted as a fall in cerebral blood flow.173 Development of the technique described in this paper has btxn prompted by the need for a method which is both non-invasive yet quantitafive, and suitable for use in the newborn infant.
Method Recently, venous occlusion plethysmography has been described for the estimation of changes in cerebral blood flow in the newborn infant.19 This technique is possible because the bones of the newborn infant’s skull are not fused at birth, and the skull is thus able to transmit cetebra1 arterial pulsations. If a mercury-in-rubber strain gauge20 is placed around the infant’s occipitofrontal head 263
