This book is an edited verbatim account of the proceedings of the Second London Workshop on Red Cell Filtration and Deformability, organised jointly by the Royal Society of Medicine and the Groupe de Travail sur la Filtration Erythrocytaire. The first such London Workshop was held on the occasion of the Second European Conference on Clinical Haemorheology in 1981 and its con clusions were published in an abbreviated form. The interest in blood filtration as a technique for assessing red cell deformability has continued to increase and there are now several hundred centres around the world using some form of filtration. It was, therefore, felt that the informal detailed discussions held by a small invited group of experts from many countries would be of more general interest and therefore worth publishing. This has been made possible by the continued interest and generous support of Hoechst. Spontaneous open discussion rather than formal presentations has been the hallmark of these workshops, with precirculation of all scientific data to the participants. We have attempted to preserve this flavour in editing the transcript of the proceedings. This, together with our anxiety for rapid publication, may have resulted in a less than finely polished text which may contain some in accuracies. The topics discussed were loosely structured into eight sessions, outlined in the accompanying programme."

Jean Natali The pathophysiology and management of chronic critical limb -ischaemia (CLI) has always been a problematic area, at least partly because it involves doc tors from a wide range of the traditional medical specialities including vascular surgery, angiology, diabetology, haematology and radiology. The treatment of these patients also varies largely with local circumstances and national traditions. CLI therefore seemed a particularly appropriate subject for a new type of European consensus approach. In 1988 a series of small workshops were held by the European Working Group on Critical Limb Ischaemia to discuss the definition, pathophysiology, in vestigation and management of this condition. The process culminated in a meet ing in Berlin in March, 1989 where 120 specialists from sixteen European countries, representing the basic sciences as well as a spectrum of clinical dis ciplines, met to evolve a Consensus Document on the subject with specific recom mendations. The Document, which is reproduced in the first section of this book, does not of course necessarily represent the unanimous view of all those who participated in its compilation; however it is agreed that it does represent a con sensus or majority view. It was also noted that the comments and recommenda tions in the document should be taken as a whole, and are not intended to dictate the only correct approach to individual treatment.

H. J. Meiselman From the theoretical studies of Dr. Skalak, it is clear that white cells can significantly influence the pressure-time profile of a red cell/white cell suspen sion, and that the presence of even a small amount of relatively rigid white cells can have a profound effect on the filtration pressure during the latter portion of a filtration experiment. Conversely, white cell effects, regardless of their relative rigidity, are shown to have only minimal effects during the very early (i. e., 0-2 seconds) phases of the filtration process. Dr. Chien's experimental data support these theoretical studies, in that white cells of different mechan ical properties exhibit different pressure-time curves; pressure-time data for mixtures of leucocytes show shapes which can be predicted from the behavior of relatively homogeneous cell populations. The insensitivity of the very early portions of the filtration process to white cells is again reflected in the calculations made by Dr. Hanss. Using the nominal dilutions, white cell concentrations and the total volume of filtered cell suspension, he indicates that usually less than 1 pore out of 100 is liable to blockage by white cells. He thus concludes that, at the 1% accuracy level, initial filtration data should not be affected by mechanical pore blockage by white cells. Experimental studies by Dr. Lowe and Dr. Stuart question the WBC insensitivity of the early portion of the filtration process. Using a constant flow system, Dr."

The task the editors have set themselves is to survey the field of clinical hemorheology from basic principles to up-to-date research. It is only in a new science like this that it is possible to span the whole field in a book of this size. Hemorheology, as a new approach to the study and management of a wide range of circulatory diseases, is now beginning to appear with increasing frequency in general as well as specialized medical journals. Hemorheology is also just beginning to creep into the undergraduate medical curriculum. Therefore, the majority of graduate doctors are unequipped to assess the place of hemorheology in the overall framework of circulatory physiology and pathology or to assess its relevance to their everyday practice. It is hoped that this book will fill this gap. The approach of the book is interdisciplinary. The first part deals with basic principles of blood flow, circulation and hemorheology. It has been written with the general doctor in mind, who has no special knowledge of hemodynamics and rheological concepts, terminology or methodology. To maintain the emphasis on practical clinical applications, all the chapters in the second part of the book have been written by clinical specialists practicing in the individual areas of disease. The book is so designed that clinicians may be able to read the relevant chapters in the second part of the book in isolation, using the basic science aspects contained in the first part of the book as reference chapters.