Debates over medical authority, new challenges in biomedical experimentation

Book reviews Chemical Sensor Technology: Volume 4 S. Yamauchi. Elsevier Science Publishers, Amsterdam, 1992,270~~. $19 1.50 ISBN O-444-98680-4 Chemical sensors now offer an analytical route to a very broad range of analytes. They truly represent an era of multidisciplinary science, as they represent a natural coming together ofphysics, chemistry and biology, the latter in the guise ofbiosensors. All ofthese subject areas have contributed to a renaissance for chemical sensors, and this is mirrored in the escalating number ofpublications in the area. Undoubtedly, there is a need for up-to-date reviews which not only introduce a topic area to the uninitiated, but also achieve sufficient depth and topicality to be ofinterest to an expert. This 4th volume of Chemical Sensor Technology achieves precisely the required balance. The 15 chapters, mainly by Japanese authors, also provide an excellent shop window for sensors, bringing across the element ofpractical importance while ensuring rigorous descriptions ofsome of the basic, underpinning science. The opening chapter is a ‘blow by blow’account of the developent of the Taguchi (semiconductor) gas sensor, giving a rare biographical glimpse ofa success story, illustrating what it takes to achieve a practical success in sensing. The semiconductor theme is maintained with a comprehensive review ofthe known theoretical basis, as well as practical operating problems ofsuch (metal-oxide based) gas sensors. The next chapter gets down to the creation of structurally elegant micromachined silicon semiconductors; the various structures are a tempting proposition, but the review makes light of their encapsulation problems and of the hitherto less adequate progress made in micromachining an equivalent reference electrode. While the subsequent chapter on adsorbed oxygen species at oxide films is of specialist chemistry interest, it does not relate well to the sensing and output side ofoxide sensor response. The next, practical description, ofthe industrial use ofcombustiontype sensors sits rather more easily in this volume. Potentiometric sensors are given an airing in a chapter on solid electrolytes used for high temperature 0s sensing and in one on an inorganic Na+ conducting membrane with a possible application to clinical measurement. Some interesting use ofa specialist cationic membrane, poly(dimethyldiallylammonium chloride), over amperometric sensors has a full chapter devoted to it, and though a somewhat narrow focus, illustrates useful measurement possibilities for the material as regards 0s and humidity. An attractive new combination ofmicromachining and sensor construction is presented by the now commercially available light-addressable potentiometric sensor (LAPS); a thorough review of the value ofthis system in monitoring enzyme- and cell-induced pH changes, with some basic theory included, is a timely inclusion. A well-trawled research area is that of mediators in electrochemical biosensors, but admittedly the chapter on immobilized mediators does have something new to offer in routes to avoiding drawbacks to mediator leaching. Piezoelectric devices are at a more basic stage of development, at least as regards their liquid phase use, with uncertainty even over mode oftransduction (e.g. microgravimetric vs viscoelastic solution change). The chapter on these devices, however, is helpful in bringing together the various different types ofdescription and in summarizing the various principles ofoperation; perhaps, though, more could have been stated on Lamb wave devices and the section on bioreagent immobilization is rather too close to textbook material. 436

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Ifreliable sensors are to be reliably fashioned from ion selective field effect transistors (ISFETs) then the method of depositing the bio/chemical sensing layer needs special attention. The chapter on the covalent binding ofsuch layers to the ISFET ‘backing’ will, therefore, be ofbroad interest and is augmented by some basic theory on response. Antigen-antibody interactions at a surface can, in principle, be monitored via some induced change in sensor charge effect; whether determination ofsurface photovoltage at a (semiconductor) surface, as described in one ofthe later chapters, is ofpractical value remains to be seen. The penultimate chapter on medical glucose measurement in aspirated subcutaneous tissue fluid (suction effusion fluid) constitutes an interesting way ofavoiding blood sampling, but one wonders whether the associated patient trauma is really diminished. The final chapter exploits intact plant leaves and their cellular transmembrane potentials as reporters ofvarious gas phase molecules; the line of approach is certainly innovative, but the data at this stage is rather unconvincing. Overall, this collection ofhigh quality reviews will be accessible to a wide scientific readership. This 4th volume deserves to be on the shelfofthose seriously in the business ofdelivering high technology sensors. P. Vadgama

Debates Over Medical Authority, New Challenges in Biomedical Experimentation Robert H. Blank and Andrea L. Bonnicksen Columbia University Press; 1993,273~~. 1993 $52.00 ISBN O-23 l-080 16-6 This text focuses on the debate over who has ‘authority’ in medical decision making. For over 15 years, citizens have struggled for power, when the time comes, to free themselves from technologies that prolong death rather than extend life, either through their own voice or through the voice offamily members. Ironically, in recent years, physicians themselves have sought power to withdraw or forego life-support mechanisms when they deem treatment futile and inhumane, but withdrawal is against the family’s wishes. Part I ofthis text presents a series ofessays that address the physician’s moral authority to refuse to administer treatment deemed futile. The Helga Wangle case, for example, possibly marks the first time physicians went to court to resist treatment they deemed futile when family members insisted that everything be done to keep the patient alive. The case ofBaby L may be the first reported time physicians refused treatment deemed futile and inhumane on a ‘patient in acute crisis’despite persistent demands by the family. To manage future conflicts ofthis kind, several essays address the creation ofnew policies in which the final arbiter, when treatment is deemed futile, is the hospital and its agencies, not the patient and family; and they look at the impact of the New York state law requiring doctors to obtain consent from the family or patient before entering a DNR order on the patient’s chart, and professional guidelines to the same effect set forth by the Joint Commission on Accreditation ofHealth Care Organizations. In still another essay, the history ofstate statutes is reviewed including the recently passed federal Patient Self-Determination Act

(PSDA) . The next moral dilemma, however, puts us on the edge of an issue, i.e. assisted death, in which consensus may be elusive or impossible. As one would expect, there are arguments to be made on each side. Reviewing some ofthe issues underlying physician-assisted suicide, arguments are provided against sanctioning aid-in-dying as a moral act, while others support the initiative. The conclusions reached

are clear. Assisted suicide touches such a wide array of societal interests that it will be a long-term issue. Part II presents two essays that deal with the issue of human experimentation particularly related to fetuses, such as the practice of‘selective termination’ in which several fetuses in a multiple pregnancy are selectively aborted. In the final essay, the risks and benefits offetal surgery are reviewed. The essays in this text cast a power of their own. They are descriptive and argumentative. Each one forces the reader to reflect and ponder about the moral dilemma posed. The issue ofpower- ofautonomy in the case of the patient, of moral independence in the case of the physician-is at the heart of the notion, ‘quality ofcare’. As such, it warrants the central focus it obtains in this text. This text serves as an excellent stimulant to the arguments raised in the ongoing ethical debates. For those engaged it is a ‘must read’. Joseph D. Bonzino

Fetal Heart Rate Monitoring: A Practical Guide I. Ingemarsson, E. Ingemarsson and J.A.D. Spencer Oxford Medical Publications, Oxford; 1993 This publication deals, in 18 sections, with the most important clinical aspects related to the use of continuous heart rate monitoring in the human fetus. The technique has been employed for more than 30 years in recording fetal heart rate (FHR) activity in both the antenatal period and at term by using a variety of sensors or transducers (ultrasonic, mco, phono, ECGelectrode, and auscultory means). Despite the fact that more than 75% ofthe deliveries in USA and Western Europe are monitored during labour, no unanimous position has been reached among obstetricians and gynaecologists about the usefulness ofcontinuously recording FHR, probably due to the poor correlation between abnormal FHR changes and the condition of the baby at birth. The book, conceived as a practical guide well correlated with numerous recordings ofvarious cases (particularly cardiotocographic signals), does not enter this specific quarrel and illustrates, in a balanced way, the pros and cons ofsuch a procedure, especially from the clinical standpoint. The authors’ position is to describe clearly their experience in the clinical interpretation of the data, by emphasizing the importance ofthe information (which is sometimes difficult to interpret) obtainable through monitoring and by remarking the fact that excessive (and notjustified) technological intervention may be not in accordance with a sensible and sensitive attitude towards pregnant women care. The most relevant topical pathophysiological cases of interest in FHR analysis are analysed: acid-base balance, hypoxia, the effects ofdrugs, acceleration and deceleration, relation to uterine contractions, preterm cases, antenatal and terminal recordings, fetal stimulation, as well as the investigation of the role ofautonomic nervous system. The book does not enter the technical issues of instrumentation and signal processing; it is therefore recommended as a primer text of FHR monitoring to obstetricians (i.e. in training), to non-medical staff, and to biomedical engineers who wish to approach the nonstationary and complex behavior ofFHR control mechanisms in a variety ofclinical cases. S. Cerutti

Bone Implanting Grafting John Older Springer-Verlag,

Berlin, 1992,226~~.

DM 170.00 ISBN

3-540- 19720-6 This book, based on a symposium held in May 199 1, provides contributions from a group of recognized international experts in the field ofgrafting, and as such, represents an authoritative exposition ofthe state ofthe art. The increasing demand for orthopaedic surgery associated with revision knee and hip arthroplasty is placing higher expectations on the design and technology of the implant systems. At the same time, as revision cases have been on the increase, the results have ben frequently disappointing due to the poor structural integrity ofthe remaining bone and the difliculty ofobtaining rigid fixation. The application of bone grafting has been seen as a potential solution. Regarding the implants themselves the introduction ofnew materials, rigorous pre-clinical evaluation, and improved design and manufacturing technology, has provided the potential for increased longevity. It is against this background that this book is compiled. The book is divided into live chapters dealing with the basic principles ofbone grafting, followed by comprehensive chapters on grafting the acetabulum, femur and the knee. The final chapter deals with the crucial aspect ofbone banking. While the book is comprehensive from a surgical point of view, it provides little coverage ofthe scientific framework. For example, the structural properties ofbone-implant constructs are not described, nor is there sufficient coverage ofthe biological aspects ofgraft incorporation, ofboth block and morselized allograft. There is also little mention of alternate materials to bone graft, which would be useful to provide some perspective. For the purposes of a biomedical engineer, this book has utility in providing a comprehensive view of the problem, thus giving the basic data for the design of better implants and instrumentation. At the same time, even though the book is primarily written for the practising orthopaedic surgeon, in today’s world oforthopaedics it should be recognized that advances are made most efficiently by including contributions from other specialities as well. Peter S. Walker

Biomechanica and Exercise Physiology Arthur T. Johnson John Wiley, Chichester; O-47 l-85398-4

1991,456~~. E66.70 ISBN

This is not a book for the faint-hearted, being full ofcomplex mathematical relationships and models describing human physiological responses under the stressful conditions of exercise. It purports to give a new perspective on physiology, and this it clearly does. It is divided into five chapters: Exercise Limitations, Exercise Biomechanics; Cardiovascular Responses; Respiratory Responses; and Thermal Responses: ofwhich the last three make up the bulk of the book (85%)) with the chapter on Respiratory Responses being by far the largest (43% ofthe book). Where appropriate, each chapter begins with a review ofthe relevant physiology, although this is often somewhat limited, before immersing the reader in equations concerning the mechanical and control aspects of the system under consideration, as well as predictively describing the physiology of an exercise response. In the chapters on Respiratory Responses and Thermal Responses several control modehare presented and compared. The author has cleverly integrated phsyiology with engineering by making extensive use ofligures and tables. In so doing, he has brought together a unique collection of information. Each chapter is fully referenced, in addition to which a comprehensive explanation ofthe symbols used in Med. Eng. Phys. 1994, Vol. 16, September

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