4. Techniques in
extracorporeal
circulation
FOURTH EDITION
Edited by
PHILIP H KAY MA DM FRCS
Consultant Cardiothoracic Surgeon,
Yorkshire Heart Centre,
The General Infirmary,
Leeds, UK
and
CHRISTOPHER M MUNSCH ChM FRCS (C/Th)
Consultant Cardiothoracic Surgeon,
Yorkshire Heart Centre,
The General Infirmary,
Leeds, UK
A member of the Hodder Headline Group
LONDON
6. Contents
Contributors vii
Foreword xi
Preface to Fourth Edition – 50 years on xiii
Preface to Third Edition xiv
Preface to Second Edition xv
Preface to First Edition xvi
Acknowledgements xvii
1 A brief history of bypass 1
Anil Kumar Mulpur and Christopher M Munsch
2 Design and principles of the extracorporeal circuit 7
Medtronic, Inc., A Manufacturer of Technologies for Extracorporeal Circulation
3 Physiology and pathophysiology of extracorporeal circulation 23
Jonathan AJ Hyde and Ralph E Delius
4 Anaesthesia for cardiopulmonary bypass 57
Linda Nel and John WW Gothard
5 Monitoring and safety in cardiopulmonary bypass 76
Jonathan M Johnson, Stephen Robins and Jonathan A J Hyde
6 Priming fluids for cardiopulmonary bypass 99
Piet W Boonstra and Y John Gu
7 Filters in cardiopulmonary bypass 108
Farah NK Bhatti and Timothy L Hooper
8 The inflammatory response to cardiopulmonary bypass 117
Saeed Ashraf
9 Pulsatile cardiopulmonary bypass 133
Terry Gourlay and Kenneth M Taylor
10 Cardiopulmonary bypass and the brain 148
G Burkhard Mackensen, Hilary P Grocott and Mark F Newman
7. vi Contents
11 Cardiopulmonary bypass in children with congenital heart disease 177
Carin van Doorn and Martin Elliott
12 Intraoperative myocardial protection 184
John WC Entwistle III and Andrew S Wechsler
13 Blood conservation 210
Mike Cross
14 Mechanical circulatory support 236
Stephen Westaby and Satoshi Saito
15 Extracorporeal membrane oxygenation 254
Scott K Alpard, Dai H Chung and Joseph B Zwischenberger
16 The extended use of the extracorporeal circuit 292
Philip H Kay, Anil Kumar Mulpur, Dumbor Ngaage, Samir Shah, Kieran Horgan,
John Pollitt and Stephen D Hansbro
17 Cardiopulmonary bypass during Port-access™ and robotic surgery 298
Alan P Kypson and W Randolph Chitwood Jr
18 Cardiac surgery without cardiopulmonary bypass 315
Joseph P McGoldrick
19A The development of clinical perfusion education and standards in the UK and Ireland 332
Michael Whitehorne
19B Standards, guidelines and education in clinical perfusion: the European perspective 337
Ludwig K Von Segesser
19C Perfusion education in the USA at the turn of the twentieth century 341
Alfred H Stammers
Index 345
8. Contributors
Scott K Alpard MD Mike Cross
Surgical Research Fellow, Consultant Anaesthetist,
Division of Cardiothoracic Surgery, Yorkshire Heart Centre,
University of Texas Medical Branch, The General Infirmary at Leeds,
Galveston, TX, USA Leeds, UK
Saeed Ashraf FRCS(CTh) MD Ralph E Delius MD
Consultant Cardiothoracic Surgeon, Children’s Hospital of Michigan,
Regional Cardiothoracic Centre, Detroit, MI, US
The Morriston Hospital, and Honorary Senior Lecturer,
University of Swansea,
Carin van Doorn
Swansea, UK
Senior Lecturer in Cardiothoracic Surgery,
Farah NK Bhatti University College London,
Specialist Registrar in Cardiothoracic Surgery, and Honorary Consultant Cardiothoracic Surgeon,
Wythenshawe Hospital, Cardiothoracic Unit,
Manchester, UK Great Ormond Street Hospital for Children,
London, UK
Piet W Boonstra
Department of Cardiothoracic Surgery, Martin Elliott
University Hospital, Consultant Cardiothoracic Surgeon,
Groningen, The Netherlands Cardiothoracic Unit,
Great Ormond Street Hospital for Children,
Walt Carpenter London, UK
Director of Cardiopulmonary R&D,
Medtronic Perfusion Systems, John WC Entwistle III MD PhD
Minneapolis, MN, USA Assistant Professor of Cardiothoracic Surgery,
Department of Cardiothoracic Surgery,
W Randolph Chitwood Jr MD
Drexel University College of Medicine,
Senior Associate Vice Chancellor and Director,
Philadelphia, PA, USA
North Carolina Cardiovascular Institute,
Professor and Chairman,
Professor of Surgery, John WW Gothard FRCA
Chief, Division of Cardiothoracic and Vascular Surgery, Consultant Anaesthetist,
The Brody School of Medicine, Royal Brompton Hospital,
East Carolina University, London, UK
Greenville, NC, USA
Terry Gourlay PhD BSc (Hons) CBiol MIBiol ILTHE FRSH
Dai H Chung MD British Heart Foundation Perfusion Specialist,
Assistant Professor of Surgery, Department of Cardiothoracic Surgery,
Chief, Section of Pediatric Surgery, NHLI,
Department of Surgery, Imperial College Medical School,
University of Texas Medical Branch, Hammersmith Hospital Campus,
Galveston, TX, USA London, UK
9. viii Contributors
Hilary P Grocott MD FRCPC G Burkhard Mackensen MD
Associate Professor, Assistant Professor,
Department of Anesthesiology, Klinik für Anaesthesiologie,
Duke Heart Center, Technische Universität München,
Duke University Medical Center, Klinikum rechts der Isar,
Durham, NC, USA München, Germany
Joseph P McGoldrick MD FRCS
Y John Gu
Consultant Cardiothoracic Surgeon,
Department of Cardiothoracic Surgery,
The Yorkshire Heart Centre,
University Hospital,
The General Infirmary at Leeds,
Groningen, The Netherlands
Leeds, UK
Stephen D Hansbro Anil Kumar Mulpur MS MCh FRCS (Edin)
Department of Clinical Perfusion, FRCS (Glasgow) FRCS C/Th (Edin) FETCS
Leeds General Infirmary, Consultant Cardiothoracic Surgeon,
Leeds, UK Sri Sathya Sai Institute of Higher Medical Sciences,
Whitefield, Bangalore, India
Timothy L Hooper
Christopher M Munsch ChM FRCS (C/Th)
Consultant Cardiac Surgeon,
Consultant Cardiothoracic Surgeon,
Wythenshawe Hospital,
Department of Cardiothoracic Surgery,
Manchester, UK
The Yorkshire Heart Centre,
The General Infirmary,
Kieran Horgan Leeds, UK
Department of General Surgery,
Leeds General Infirmary, Linda Nel FRCA
Leeds, UK Consultant Anaesthetist,
Southampton University Hospitals Trust,
Jonathan AJ Hyde MD FRCS(CTh) Southampton, UK
Consultant Cardiac Surgeon, Mark F Newman MD
Royal Sussex County Hospital, Professor and Chairman,
Brighton, UK Department of Anesthesiology,
Duke Heart Center,
Jonathan M Johnson BSc ACP Duke University Medical Center,
Chief Clinical Perfusionist, Durham, NC, USA
Royal Sussex County Hospital,
Brighton, UK Dumbor Ngaage
Department of Cardiothoracic Surgery,
Leeds General Infirmary,
Bruce Jones
Leeds, UK
Cardiopulmonary Product Manager,
Medtronic Perfusion Systems, John Pollitt
Minneapolis, MN, USA Department of General Surgery,
Leeds General Infirmary,
Philip H Kay MA DM FRCS Leeds, UK
Consultant Cardiothoracic Surgeon,
Stephen Robins PgDip AACP
The Yorkshire Heart Centre,
Chief Clinical Perfusionist,
The General Infirmary,
New Cross Hospital,
Leeds, UK
Wolverhampton, UK
Alan P Kypson MD Satoshi Saito MD PhD
Assistant Professor of Surgery, Senior Clinical Research Fellow,
Division of Cardiothoracic Surgery, Department of Cardiothoracic Surgery,
Brody School of Medicine, Oxford Heart Centre,
East Carolina University, John Radcliffe Hospital,
Greenville, NC, USA Oxford, UK
10. Contributors ix
Ludwig K Von Segesser Andrew S Wechsler MD
Service de Chirurgie Cardio-Vasculaire, Professor and Chairman,
Centre Hospitalier Universitaire Vaudois (CHUV), Department of Cardiothoracic Surgery,
Lausanne, Switzerland Drexel University College of Medicine,
Philadelphia, PA, USA
Samir Shah
Department of Cardiothoracic Surgery, Stuart Welland
Leeds General Infirmary, European Marketing Manager,
Leeds, UK Medtronic Europe Sàrl,
Tolochenaz, Switzerland
Alfred H Stammers MSA CCP
Chief Perfusionist, Stephen Westaby PhD FETCS MS
Department of Surgery, Consultant Cardiac Surgeon,
Geisinger Medical Center, Department of Cardiothoracic Surgery,
Danville, PA, USA Oxford Heart Centre,
John Radcliffe Hospital,
Editor, Journal of Extracorporeal Technology
Oxford, UK
Jeanne Stanislawski Michael Whitehorne MSC ACP FCCPS
Cardiopulmonary Product Manager,
Consultant Clinical Perfusion Scientist,
Medtronic Perfusion Systems,
Department of Cardiothoracic Surgery,
Minneapolis, MN, USA
King’s College Hospital,
Wendy Svee London, UK
Cardiopulmonary Product Manager, Joseph B Zwischenberger MD
Medtronic Perfusion Systems, Professor of Surgery, Medicine, and Radiology,
Minneapolis, MN, USA Director, General Thoracic Surgery and ECMO Programs,
Kenneth M Taylor Division of Cardiothoracic Surgery,
Professor of Cardiac Surgery, University of Texas Medical Branch,
Department of Cardiothoracic Surgery, Galveston, TX, USA
NHLI,
Imperial College Medical School,
Hammersmith Hospital Campus,
London, UK
12. Foreword
I am most grateful to the editors for their invitation to preference for medical revascularisation (percutaneous
write the foreword for this – the fourth edition of transluminal coronary angioplasty, stents, the expanding
Techniques of Extracorporeal Circulation. My office book- range of percutaneous coronary interventions) at the
case currently contains the three previous editions, and expense of what we used to consider the unassailable
if I am not considered presumptuous, I look forward to gold standard: conventional coronary artery bypass graft
adding a copy of this fourth edition. surgery.
John Gibbon received international acclaim for his For cardiopulmonary bypass and the perfusion pro-
courage and determination on the 50th anniversary of fessionals, the challenge was different, but no less daunt-
that historic open-heart operation in Philadelphia on ing: would off-pump coronary bypass render the use of
May 5th 1953 when the heart–lung machine was used cardiopulmonary bypass in coronary surgery obsolete?
successfully in a patient for the first time. Fifty years does One might reasonably assume that now is not the time to
not seem to me to be that long, although when I was invest in cardiopulmonary bypass – far too risky! I beg
younger (i.e. not over 50) my opinions were different. It to differ, however. I would suggest that now is precisely
is always fascinating to hear graphic personal accounts of the time for investment in cardiopulmonary bypass.
those early days of cardiopulmonary bypass where the It should, however, be specifically targeted investment,
challenges seemed almost insuperable. a balanced investment portfolio.
Things are very different 50 years on. The technology First, the further continual refinement of cardio-
and the practice of cardiopulmonary bypass have been pulmonary bypass remains as great a challenge and an
refined to an exceptional degree. The benefits to the car- opportunity now as it was in the 1950s. Developments in
diac surgical patients and the cardiac team of surgeons, medicine in general (particularly including molecular
anaesthetists, perfusionists and nursing staff have been science and genetics/genomics) offer great potential to
incalculable. I was asked a few years ago to give a talk on increase our understanding of the fundamental patho-
the topic: ‘Can cardiopulmonary bypass become more physiological mechanisms of cardiopulmonary bypass
patient friendly?’ I observed at the start of the talk that and consequently introduce more effective preventative
cardiopulmonary bypass had been a great friend to cardiac and therapeutic strategies.
surgical patients and to cardiac surgeons and their col- Second, we need to broaden our horizons as far as
leagues, and that John Gibbon would be turning over in extracorporeal circulation is concerned. Its potential roles
his grave at the very thought of the topic I had been given. in other forms of surgery (both in cardiac and non-
I was exaggerating of course, and Gibbon and his fellow cardiac) in local circulations and in systemic circulatory
pioneers would be the very last to encourage complacency and respiratory support present a wealth of opportunities.
regarding cardiopulmonary bypass. As it so happened, the Third and finally, to quote the UK Prime Minister Tony
following year I was asked to speak to another question: ‘Is Blair (who interestingly was born on May 5th 1953 –
cardiopulmonary bypass in 2001 as good as it gets?’ I trust Gibbon’s historic day) ‘... education, education, education’.
you will already have worked out that I was somewhat We need to apply ourselves, both individually and in the
negative in my response to that proposition! medical and perfusion schools of the future. New science
They say that things come along in threes – and it fell brings with it new terminologies – we need to learn the
to me to address another cardiopulmonary bypass languages. Then we can communicate with the basic sci-
related question in 2002. ‘Would you invest in cardiopul- entists, with molecular experts, with geneticists and who
monary bypass in 2002?’ was the title. I found this exer- knows who else!
cise particularly interesting. By then, cardiac surgery and It may be a daunting prospect for us, but spare a
cardiopulmonary bypass were each facing major chal- thought also for the basic scientists – when have they ever
lenges to their future importance. For cardiac surgery, before been visited by an enthusiastic perfusionist or
the challenge – indeed the threat – was the increasing cardiac surgical trainee?
13. xii Foreword
So these are the challenges, and the opportunities. honourable tradition of risk-takers. As one of the North
This textbook will help considerably. Philip Kay and American insurance corporations proclaims in its adver-
Chris Munsch have brought into this book the right tising: ‘the only risk is not to take one’.
subjects and the right authors. This book contains a lot of John Gibbon would profoundly agree with that.
information, which can be a launch pad for new ideas
and new questions. Professor Kenneth M Taylor MD FRCS
Are there risks? Of course there are! We must never FRCSE FESC FETCS FSA
forget, however, that in cardiac surgery we come from an BHF Professor of Cardiac Surgery
14. Preface to Fourth Edition — 50 years on
In May 1953 Edmund Hilary and Sherpa Tensing became surgery make the clinical perfusionist obsolete? Whatever
the first men to stand on the summit of Mount Everest. happens there is no doubt that clinical perfusion will con-
In that same month came John Gibbon’s moment of tri- tinue to evolve and develop. We believe that this fourth
umph, with the first successful use of mechanical car- edition of Techniques in Extracorporeal Circulation
diopulmonary bypass in a human patient. deserves a place on the bookshelves of all healthcare pro-
The seed had been sown and it subsequently fell to fessionals working in the cardiac surgical operating room.
other pioneers to develop the science of extracorporeal We suspect, in an era of electronic communication, that
circulation. the bookshelf may well be the first to become obsolete.
Leeds was at the forefront of this exciting development Progress in surgery is often compared with moun-
and, in 1957, Geoffrey Wooler used cardiopulmonary taineering and exploration (and contributors to this
bypass to repair a mitral valve. He then went on to edit the book have themselves used the analogy). A lot has hap-
first edition of Techniques in Extracorporeal Circulation, pened in both spheres in the past 50 years. With that in
published in 1976. The change in authorship and content mind, we would like to follow in John Hunt’s illustrious
of the subsequent three editions reflects the evolution of footsteps and, as he did in The Ascent of Everest, dedicate
the speciality over a generation of cardiac surgery. this book … ‘To those who made it possible’.
Who, reading the first edition, would have predicted
that the fourth edition, 27 years later, would contain chap- Philip Kay and Chris Munsch
ters on robotic surgery and off-pump surgery? Will the Leeds
combined threat of increasing angioplasty and off-pump 2003
15. Preface to Third Edition
The heart is a unique organ, simple in concept as a mus- The first edition of this book, edited by Mr M. Ionescu
cle pump, but complex in design and function. Heart and Mr G. Wooller 16 years ago, laid a solid foundation for
failure, from whatever cause, remains the commonest the student of extracorporeal circulation. It was followed
cause of death in the western world. by a second edition five years later and, after a further 11
It is now almost 100 years since von Reyn contravened years, by this edition. Yet progress in this field is so fast that
the dictates of Billroth, risked ‘loosing the esteme of many of the new developments in this book were not even
his colleagues’ and successfully operated on the heart. contemplated in the final ‘future developments’ chapter of
However, cardiac surgery proceeded at a slow pace until the second edition, and so I am sure will be the case for the
the development of the extracorporeal circuit. Thereafter fourth edition. Similarly, much progress has been made
the understanding of the complex anatomy, biochem- during the three years it has taken to produce this book.
istry, pharmacology and physiology of the heart has Nevertheless, this edition, like the original, provides a firm
enabled us to take great strides in the complex repair basis for doctors, nurses, perfusionists and physicians’
work that is now so common place in the operating assistants alike, all students of the extracorporeal circula-
room. Concomitantly, advances in rheology and material tion and its ever increasing number of applications.
science have provided a wider safety margin and there- I hope that it will stimulate its readers to continuing
fore expanded the number of patients able to benefit the pioneering interface between the lone surgeon and
from cardiac surgery. It is these advances that form the the increasingly complex machinery that surrounds him.
basis of the third edition of Techniques in Extracorporeal
Circulation. P.H. Kay
16. Preface to Second Edition
The preface to the first edition of this book was preceded theoretical aspects of extracorporeal circulation but does
by Michelangelo’s humble remark ‘ancora imparo’. Even not necessarily provide final answers.
for the contents of this small book on techniques in In an effort to keep abreast of the many advances
extracorporeal circulation it proved its timeless veracity which have occurred, a number of additional topics have
as we ‘continue to learn’. been included in this present edition. Several new, out-
The first edition, however, despite many short-com- standing contributors have participated, whilst the great
ings, has fulfilled its role. majority of those chapters which appeared in the first
During the past few years the energetic clinical and edition have been updated or augmented.
research activities have led to many advances and have Despite the awareness of discontinuity and reitera-
further broadened the concept of artificial circulation tion, this second edition of Techniques in Extracorporeal
and oxygenation so that an increasing number of sub- Circulation retains the structure of most modern books
specialties are now attaining a certain contour. by being comprised of a series of individual chapters.
In recent years, several areas of extracorporeal circula- I wish to express my enthusiasm for the privilege of
tion have assumed increasing importance. The progress editing this text and gratefully acknowledge the out-
made in the field of ischaemic heart disease and the standing contributions of the authors who have joined in
major impact of myocardial protection through cardio- this endeavour.
plegia are only two of the most obvious examples. I should like to thank Miss Wendy Lawrence for the
Refinements in the construction and performance of complex and seemingly endless secretarial work.
bubble oxygenators and the introduction of disposable My sincere appreciation is extended to Messrs
membrane oxygenating systems have changed the tech- Butterworths for their unfailing attention to detail and
niques of heart–lung bypass and broadened its scope. for the maintenance of the high standards for which they
Many pioneers in these fields have discovered and redis- are known.
covered noteworthy features of great clinical significance.
This second edition attempts to summarize the major
technical problems and touches on some of the more Marian I. Ionescu
17. Preface to First Edition
ancora imparo single volume standard current techniques in extracorpor-
Michelangelo Buonarotti eal circulation along with the more recent developments
in this field. This is an attempt to answer some of the
Extracorporeal circulation with an artificial heart-lung innumerable practical problems associated with the rou-
machine has established itself as the routine adjunct to tine use of artificial circulation and oxygenation and to
intracardiac and vascular surgery. Since its introduction present some models of standardized techniques.
in 1953, this method has been progressively improved by A major problem with such a book is to decide what to
development and simplification of the equipment and by include and what to omit. We are aware that omissions
better understanding of the body response to the alter- have been made, but we have aimed to keep the subject
ations induced by the use of artificial perfusions. matter strictly circumscribed in the interest of text size and
The method, established in the experimental labora- readability. The esoteric has been omitted on purpose and
tory, has been perfected by clinical use. For many poorly emphasis is placed on the current practical methodology.
understood aspects the method has continued to be Advances in modern surgical and perfusion techniques
investigated in the laboratory, where answers and solu- have been developed to such a degree that an entirely new
tions have been found for innumerable bewildering and spectrum of problems evolves with each new develop-
knotty clinical problems. ment. Such rapid changes and improvements will certainly
A superficial look at today’s methods would give the call for another publication in the near future, and this is
uninformed the general impression that no substantial another reason for limiting the size of this book.
progress has been made in the past ten years. For example, Since this is a multi-authored book and the chapters
the same principle of bubble oxygenation used at the begin- are designed to be read separately, some reiteration has
ning of the open-heart surgery era is almost universally been inevitable, although an attempt was made to avoid
employed today. The same may be said for metallic pros- repetition.
thetic valves with a ball or disc occluder mechanism. The Major attention has been focused on the cardio-vascular
best method for ‘myocardial preservation’ during open- system, the lung, the renal function and haematological
heart surgery is yet to be established and the Montagues of changes. Clearly the brain, liver, gut, muscle masses and
hypothermia still have to convince the Capulets of coronary reticuloendothelial system are of great importance in the
perfusion of the veracity and superiority of their principle body response to extracorporeal circulation, but the meas-
just as much as they had to ten years ago. urement of their function in the cardiovascular patient is
On closer examination, one realizes that during the at the moment largely in the realm of the investigator.
past ten years an enormous wealth of data and knowledge Although the principles and techniques described have
has been accumulated and the application of this know- become routine for practical purposes, they are by no
ledge has made clinical perfusions incomparably better means beyond challenge. As William Hazlitt put it ‘when
and safer. The results of cardiovascular surgery obtained a thing ceases to be a subject of controversy, it ceases to be
today, whether in the newborn or the elderly, for great a subject of interest’.
arteries or coronary arteries, in routine cases or in emer- The Editors join the contributors in hoping that this
gencies, when compared with the results obtained only volume will be of interest to those active in the field of
ten years ago, are the best proof of progress and continu- cardiovascular surgery.
ous improvement in extracorporeal circulation. We take great pleasure in expressing our thanks to
During the past few years many new and exciting prin- Dr Frank Gerbode for kindly writing the Foreword of
ciples and techniques based on extracorporeal circulation this work. We are grateful to Miss Nancy Evans for her
have been brought into clinical use. Deep hypothermia for continuous and enthusiastic help.
heart surgery in the newborn, prolonged extracorporeal Completion of this book within a few months was
oxygenation-perfusion for pulmonary insufficiency and promised, but it has taken almost two years and we
intra-aortic balloon pumping for circulatory assistance are appreciate the forbearance and continuous help of our
some of the major achievements of the past decade. publishers, Butterworth and Co. Ltd.
The paucity of books devoted exclusively to extracor-
poreal circulation has prompted us to bring together in a M.I. Ionescu
18. Acknowledgements
Philip H Kay and Christopher M Munsch would like to We are also indebted to everyone at Hodder Arnold who
thank the individual chapter authors for their skilful and worked so hard to make it happen.
patient contributions to this beautifully crafted book.
20. 1
A brief history of bypass
ANIL KUMAR MULPUR AND CHRISTOPHER M MUNSCH
Introduction 1 Hypothermia 4
The first heart–lung machine 1 Heparin 4
Oxygenation 2 Summary 5
Pumping the blood 4 Further reading 5
Haemodilution 4 References 5
INTRODUCTION THE FIRST HEART–LUNG MACHINE
The history of cardiopulmonary bypass is, in many ways, The concept of cardiopulmonary bypass is rightly
a miniature representation of the history of all surgery. credited to Dr John Heysham Gibbon Jr (1903–1973).
The discoveries and the experiments, the longed-for Dr Gibbon came from a family of doctors and was work-
triumphs and the all too frequent disasters, the blood ing with Dr Churchill at Harvard Medical School. In
(especially the blood), the sweat and the tears of years of October 1930 a female patient, who had undergone
surgical endeavour are all mirrored in the evolution of a cholecystectomy two weeks before, collapsed due to
cardiac surgery. In 1880 Billroth stated that ‘any surgeon pulmonary thrombo-embolism. Dr Churchill did under-
who wishes to preserve the respect of his colleagues, take a pulmonary embolectomy on her, but in that era
would never attempt to suture the heart’. What was once there were no survivors of this procedure in the USA.
considered hazardous, outrageous or even sacrilegious Dr Gibbon looked after this patient in her last stages.
has now become routine and commonplace. There is no This led to the genesis of an idea that Dr Gibbon outlined
doubt that the bravery and determination of the pion- (Gibbon, 1970):
eers (both doctors and patients) has seen bypass develop
rapidly. Most cardiac surgeons these days prefer their During that long night, helplessly watching the patient
heart surgery to be, if not boring, then at least not too struggle for life as her blood became darker and veins
exciting. more distended, the idea naturally occurred to me that if
Much has been written about the history of cardio- it were possible to remove continuously some of the blue
pulmonary bypass and the development of cardiac sur- blood from the patient’s swollen veins, put oxygen into
gery. The interested reader, particularly one with an eye that blood and allow carbon dioxide to escape from it,
for the flamboyant, is recommended to study Landmarks and then to inject continuously the now-red blood back
in Cardiac Surgery (Westaby and Bosher, 1997). This into the patient’s arteries, we might have saved her life.
chapter could never compete in such exalted company We would have bypassed the obstructing embolus and
and, in fact, subsequent chapters in the current book performed part of the work of the patient’s heart and
will cover the historical background to specific areas of lungs outside the body.
bypass in greater detail. Therefore, this introductory
chapter will simply document some of the major mile- Dr Gibbon set out to devise a mechanical pump oxy-
stones in the (relatively short) journey from impossible genator and, with his wife Mary Hopkinson, spent the
to mundane. next 20 years in pursuit of his goal. The heart–lung
21. 2 A brief history of bypass
machine Model I was built by International Business carbon dioxide removal. It seemed that what was actually
Machines (IBM) laboratories in 1949, by which time needed was in fact a lung, either natural or artificial.
Gibbon was able to keep small dogs on bypass with only
10 per cent mortality, and by 1951 a machine for clinical
use was built. In 1953, using Model II, an atrial septal defect The lungs
was closed successfully on cardiopulmonary bypass, for
the first time in history. In 1956, Campbell reported successful cardiac surgical
However, this momentous occasion had much of procedures in humans on bypass, by use of dog lungs
the feel of a false dawn. Gibbon operated on four further (Campbell et al., 1956), and Mustard and co-workers
patients, all of whom died. He became disillusioned with reported the use of scrupulously washed monkey lungs
the technique and critical of his own surgical abilities, for oxygenation in human cardiac surgery in 1954. These
and called a halt to the programme. experiments, although seemingly moderately successful,
All was not lost though, and John Kirklin, using a were extremely complicated and soon abandoned
modified Model II, operated on eight patients with intra- (Mustard et al., 1954; Mustard and Thomson, 1957). In
cardiac defects, with just four deaths, only one of which 1958 Drew used patients’ own lungs as the oxygenator,
he attributed directly to complications of bypass. The with a combination of right and left heart bypass and
impetus had been regained and further progress in profound hypothermia (Drew and Anderson, 1959). With
mechanical cardiopulmonary bypass was stimulated. this technique, the time available for surgical repair was
increased and more complex abnormalities could be
addressed (Westaby and Bosher, 1997).
OXYGENATION
The historical development of oxygenators is summar- Cross-circulation
ized in Fig. 1.1. Many methods of oxygenating the blood
have been investigated over the years. Early experiments Andreasen and Watson conducted some canine experi-
involved actually injecting oxygen directly into the blood ments in Kent, England and published their results
stream, whilst other equally inventive techniques of oxy- in 1952. If the superior vena caval entry into the heart
genation were attempted and soon abandoned. These was snared at the cavo-atrial junction, no dog survived
early experiments focused purely on artificial oxygen- beyond 10 minutes. If the snare was distal to azygos vein,
ation, without concerning themselves with the need for allowing azygos venous flow into the right atrium, there
Oxygenators
Natural Artificial
oxygenators oxygenators
Heterologous Homologous
oxygenators oxygenators
Dog Monkey
lungs lungs
Controlled
cross-circulation
Bubble Film Membrane
Figure 1.1 Development of oxygenators for
oxygenator oxygenator oxygenator
cardiopulmonary bypass.
22. Oxygenation 3
was adequate flow to prevent cerebral damage for up to sheet oxygenator, and improved the DeWall–Lillehei
40 minutes. This finding challenged the existing notion bubble oxygenator further, which meant that the bub-
that flows equivalent to normal cardiac output were nec- ble oxygenator became available as a sterile sealed unit.
essary to prevent damage to vital centres, and suggested This development played a significant role in expanding
that in fact only eight to nine per cent of normal flow was cardiac surgery beyond Minnesota (Gott et al., 1957a,b).
needed (Andreasen and Watson, 1952). Naef (1990) wrote:
Lillehei, at the University of Minnesota, recognized
the significance of these findings for cardiac surgery the home made helix reservoir bubble oxygenator of
(Lillehei, 2000). After a series of careful experiments DeWall and Lillehei, first used clinically on May 13, 1955,
(Cohen and Lillehei, 1954), he introduced the technique went to conquer the world and helped many teams to
of ‘controlled cross-circulation’. As the name suggests, embark on the correction of malformations inside the
the technique used an adult whose circulation was con- heart in a precise and unhurried manner. The road to open-
nected to a child patient, the adult subject acting as the heart surgery had been opened.
oxygenator. In Lillehei’s own words, ‘controlled’ refers to
the use of a pump to precisely control the balance of the DeWall went on to develop the bubble oxygenator fur-
volume of blood flowing into and out of the donor and ther and introduced the oxygenator and omnithermic
the patient. heat exchanger in a disposable and pre-sterilized poly-
This was a daring and innovative idea. These oper- carbonate unit (DeWall et al., 1966). With the advent of
ations carried a theoretical 200 per cent mortality. In fact, better technology, and safer operations under more con-
there was no donor mortality in 45 operations. Of 45 trolled circumstances, surgeons were, for the first time,
patients, 28 survived and were discharged from hospital, appreciating the intricacies of pathologic anatomy in
many surviving for as long as 30 years (Lillehei et al., congenital and acquired heart disease, and leading to the
1986). Controlled cross-circulation, however, was limited development of surgical techniques in the present form.
in its use and could not fully support the circulation. At
the same time, more conventional forms of extracorporeal
circulation were being developed, and before long Lillihei Film oxygenators
himself went on to develop a new pump oxygenator.
Gibbon developed a film oxygenator with a rapidly
revolving vertical cylinder. The film itself was a thin film
Bubble oxygenators of blood on the metal plate, where the oxygenation took
place. In the first model, there was no reservoir. Gas flow
Simple measures to bubble oxygen into the blood met included a 95 per cent oxygen and five per cent carbon
with disastrous results because of air embolism. Clark and dioxide mixture at 5 L/min. The venous and arterial sides
co-workers had a breakthrough in 1950, when they started of the oxygenators had roller pumps and blood passed
to use small glass beads or rods coated with DC Antifoam through tubing, which was immersed in a waterbath
A, made by the Dow Corning Company in Michigan to maintain a constant temperature throughout the per-
(Clark et al., 1950). This concept was further developed by fusion. Flows of up to 500 mL/min were generated with
Lillehei and DeWall, who used a spiral settling tube with a the initial model (Gibbon, 1937). Next, a wire mesh was
helical system that largely eliminated bubbles. The initial introduced to produce a turbulent blood–gas interface
models were sterilized and re-used. Later on, disposable to improve oxygenation (Gibbon, 1954). This was fur-
bubble oxygenators were developed. The first clinical use ther improvised at the Mayo Clinic, with 14 wire meshes
of the DeWall–Lillehei bubble oxygenator was on 13 May enclosed in a lucite case. Blood flowed onto the screens
1955, for a three-year-old child with a ventricular septal through a series of 0.6 micron slots. Gas flow was 10 L of
defect and pulmonary hypertension. By use of normo- oxygen, and the carbon dioxide flow was varied depend-
thermia, a Sigmamotor pump and flows of 25–30 mL/kg, ing on the pH of the blood (Kirklin et al., 1955). However,
Lillehei reported the first success story with the bubble compared with the DeWall–Lillehei bubble oxygenator,
oxygenator (Lillehei et al., 1956). the Mayo Clinic Gibbon film oxygenator, although impres-
Bubble oxygenators were later refined to serve adult sive, was handcrafted and expensive, and difficult to use
patients. The Rygg–Kyvsgaard bag (Rygg and Kyvsgaard, and maintain.
1956) combined the bubbling and settling chambers Kay and Cross developed a rotating disk film oxygena-
with a reservoir, all in one plastic bag. Sponges made of tor in Cleveland, USA. Although this device did become
polyethylene and coated with antifoam agent were used commercially available, it had serious drawbacks in
for bubble removal. This model was manufactured in terms of ease of use, massive priming volumes, and diffi-
Denmark. Up to 3 L/min flows were possible. Gott and culty in cleaning and sterilizing (Cross et al., 1956; Kay
co-workers developed a self-contained unitized plastic et al., 1956).
23. 4 A brief history of bypass
Membrane oxygenators priming of the cardiopulmonary bypass circuits. DeWall
and Lillehei subsequently confirmed the benefits of
By 1944, Kolff had refined a cellophane membrane appar- haemodilution on cardiopulmonary bypass (DeWall and
atus for dialysis as an artificial kidney. He later tried to Lillehei, 1962; DeWall et al., 1962; Lillehei, 1962). Despite
use this as a membrane oxygenator, but found it to be abundant literature, the actual degree of acceptable
inefficient (Kolff and Berk, 1944; Kolff and Balzer, 1955). haemodilution remains controversial even today.
However, Clowes and Neville developed a teflon mem-
brane oxygenator for human usage in 1957. The mem- HYPOTHERMIA
brane area was 25 m2, but the oxygenator was bulky with
problems of sterilization and assembly (Clowes and
Neville, 1957). Once silicone became available as a mem- Historically, it is interesting to note that hypothermia
brane with satisfactory permeability to both oxygen and usage in cardiac surgery precedes the development of
carbon dioxide, Bramson and colleagues (Bramson et al., cardiopulmonary bypass. Following his earlier work on
1965) reported a new disposable membrane oxygenator the treatment of frostbite, William Bigelow had already
with integral heat exchanger. This model had 14 cells, done extensive experimental work on dogs on the physio-
each having a silicone rubber membrane across which logical effects of hypothermia (Bigelow et al., 1950). He
diffusion took place. Bodell et al. (1963) proposed the predicted the possible use of hypothermia in cardiac
use of tubular capillary membranes instead of film, and surgery thus:
this notion led to the hollow-fibre membrane oxygen- The use of hypothermia as a form of anesthetic could
ators. Not to be outdone, Lillehei was also associated with conceivably extend the scope of surgery in many new
the availability of the first compact, disposable and directions. A state in which the body temperature is low-
commercially manufactured membrane oxygenator for ered and the oxygen requirements of tissue are reduced to
clinical use (Lande et al., 1967). a small fraction of normal would allow exclusion of organs
from the circulation for prolonged periods. Such a technic
might permit surgeons to operate upon the ‘bloodless
PUMPING THE BLOOD heart’ without recourse to extra corporal pumps, and
perhaps allow transplantation of organs.
A critical component of the heart bypass apparatus is These experiments soon led to the use of hypothermia
some form of efficient atraumatic mechanical pump. A alone, with inflow occlusion but without cardiopul-
variety of pumping devices was developed before the dou- monary bypass, for the treatment of atrial septal defects.
ble roller pump became widely used. Dale and Schuster On 2 September, 1952 Dr F. John Lewis and his team
(1928) developed a diaphragm pump with valved inlet closed an ostium secundum atrial septal defect in a five-
and outlet ports, but a single pump could not generate year-old girl on inflow occlusion and moderate total
sufficient flow, so Jongbloed used six pumps of this type in body hypothermia.
parallel to conduct cardiopulmonary bypass (Jongbloed, Gollan should be given the credit of working on
1949). In Minnesota, Lillehei’s group initially used a mul- the concept of combining hypothermia and cardiopul-
ticam activated sigmamotor pump. monary bypass, before either actually became clinically
However, as early as 1934, DeBakey had modified a applicable (Gollan et al., 1955). Sealy, of Duke University,
previously available Porter–Bradley roller pump for rapid North Carolina, USA, subsequently employed a combin-
blood transfusion (DeBakey, 1934). This pump was applied ation of cardiopulmonary bypass and hypothermia for
to cardiopulmonary bypass, and rapidly became – and the first time in a clinical situation for closure of atrial
remains – the most common type of pump in use for septal defect and this operation lasted for seven hours
clinical perfusion. and 15 minutes! By 1958, Sealy reported a series of 49
patients operated on by the combined technique (Sealy
et al., 1958). As mentioned previously, Drew took the
HAEMODILUTION
temperature down to 12–15°C and pioneered the con-
cept of circulatory arrest for cardiac surgery (Drew and
Two major problems were identified in patients after car- Anderson, 1959).
diopulmonary bypass, namely ‘post-perfusion syndrome’
and ‘homologous blood syndrome’. In the early days
the oxygenators and the circuit were primed with donor
HEPARIN
blood. Zuhdi et al. (1961a, 1961b), however, developed
the concept of haemodilution with five per cent dextrose It is almost impossible to imagine the conduct of
and thus began the usage of clear priming or crystalloid cardiopulmonary bypass without the use of heparin.
24. References 5
The discovery of heparin is an interesting story (Jaques, REFERENCES
1978), and in the history of medicine is quoted as a classi-
cal example of ‘serendipity’. Horace Well coined this term
Andreasen, A.T., Watson, F. 1952: Experimental cardiovascular
in 1754; ‘The Three Princes of Serendip’, was the title of a
surgery. British Journal of Surgery 39, 548–51.
fairy tale in which the heroes were always making fortu- Bigelow, W.G., Lindsay, W.K., Greenwood, W.F. 1950: Hypothermia:
nate discoveries (Concise OED, 2002). McLean was a med- its possible role in cardiac surgery. An investigation of factors
ical student working with W. H. Howell in 1916, on the governing survival in dogs at low body temperatures. Annals of
nature of ether soluble procoagulants, and by chance dis- Surgery 132, 849–66.
covered a phospholipid anti-coagulant. Some years later Bodell, B.R., Head, J.M., Head, L.R. 1963: A capillary membrane
a water-soluble mucopolysaccharide was identified by oxygenator. Journal of Thoracic and Cardiovascular Surgery 46,
Howell, and this proved to be heparin (McLean, 1959). 639–50.
Even today, except in very rare circumstances, where it Bramson, M.L., Osborn, J.J., Main, F.B. et al. 1965: A new
cannot be used, because of genuine hypersensitivity or disposable membrane oxygenator with integral heat
exchanger. Journal of Thoracic and Cardiovascular Surgery 50,
heparin-induced thrombocytopenias, heparin and car-
391–400.
diopulmonary bypass are inseparable.
Campbell, G.S., Crisp, N.W., Brown, E.B. Jr. 1956: Total cardiac
bypass in humans utilising a pump and heterologous lung
oxygenator (dog lung). Surgery 40, 364–71.
SUMMARY Clark, L.C., Gollan, F., Gupta, V.B. 1950: The oxygenation of blood by
gas dispersion. Science III, 85–7.
Clowes, G.H.S., Neville, W.E. 1957: Further development of a blood
The history of cardiopulmonary bypass is a truly fascinat-
oxygenator dependent upon the diffusion of gases through
ing story. Against many difficulties, with a combination
plastic membranes. Transactions of the American Society for
of perseverance, intellect and skill, the early pioneers Artificial Internal Organs 3, 53–8.
developed the art of cardiopulmonary bypass as we see Cohen, M., Lillehei, C.W. 1954: A quantitative study of the ‘azygos
it today. A large range of congenital and acquired heart factor’ during vena caval occlusion in the dog. Surgery,
diseases can be treated surgically with the aid of cardiopul- Gynecology and Obstetrics 98, 225–32.
monary bypass. With advancing technology, cardiopul- Concise Oxford English Dictionary (Tenth edition). 2002: Oxford:
monary bypass continues to develop. Advances such as Oxford University Press.
heparin-bonded circuits, methods minimizing systemic Cross, F.S., Berne, R.M., Hirose, Y. et al. 1956: Description and
inflammatory response, percutaneous applications of evaluation of a rotating disc type reservoir oxygenator.
bypass, port access surgery, continued improvement in Surgical Forum 7, 274–8.
Dale, H.H., Schuster, E.A. 1928: A double perfusion pump. Journal
oxygenators and ventricular assist devices; all these and
of Physiology 64, 356–64.
others will change the picture of cardiopulmonary bypass
DeBakey, M.E. 1934: A simple continuous flow blood transfusion
beyond recognition, and the present day will then become instrument. New Orleans Med Surg J 87, 386–9.
the history. DeWall, R., Lillehei, C.W. 1962: Simplified total body perfusion-
reduced flows, moderate hypothermia and hemodilution.
Key early events in the development of Journal of the American Medical Association 179, 430–4.
DeWall, R., Lillehei, C.W., Sellers, R. 1962: Hemodilution perfusion
extracorporeal circulation
for open heart surgery. New England Journal of Medicine 266,
1078–84.
• 1916: McLean; discovery of heparin. DeWall, R.A., Bentley, D.J., Hirose, M. et al. 1966: A temperature
• 1930: Gibbon; initial idea of cardiopulmonary bypass. controlling (omnithermic) disposable bubble oxygenator for
• 1934: DeBakey; concept of roller pump for total body perfusion. Diseases of the Chest 49, 207–11.
extracorporeal circulation. Drew, C., Anderson, I.M. 1959: Profound hypothermia in cardiac
• 1950: Bigelow; profound hypothermia for open- surgery. Lancet April 11: 748–50.
heart surgery. Gibbon, J.H. Jr. 1937: Artificial maintenance of circulation during
• 1953: Gibbon; first successful clinical use of experimental occlusion of pulmonary artery. Archives of Surgery
34, 1105–31.
cardiopulmonary bypass.
Gibbon, J.H. Jr. 1954: Application of mechanical heart and
• 1954: Lillehei; use of controlled cross-circulation.
lung apparatus to cardiac surgery. Minnesota Medicine 37,
171–80.
Gibbon, J.H. Jr. 1970: The development of the heart–lung
FURTHER READING apparatus. Rev Surg 27, 231–44.
Gollan, F., Phillips, R., Grace, J.T. et al. 1955: Open left heart
• General reading: Westaby, S., Bosher, C. 1997: Landmarks in surgery in dogs during hypothermic asystole with and without
cardiac surgery. Oxford: ISIS Medical Media, 1997. A very extracorporeal circulation. Journal of Thoracic Surgery 30,
well-written book on the history of cardiac surgery. 626–30.
25. 6 A brief history of bypass
Gott, V.L., DeWall, R.A., Paneth, M. et al. 1957a: A self contained, Lillehei, C.W., DeWall, R.A., Read, R.C. et al. 1956: Direct vision
disposable oxygenator of plastic sheet for intracardiac surgery. intracardiac surgery in man using a simple, disposable artificial
Thorax 12, 1–9. oxygenator. Diseases of the Chest 29, 1–8.
Gott, V.L., Sellers, R.D., DeWall, R.A. et al. 1957b: A disposable Lillehei, C.W., Varco, R.L., Cohen, M. et al. 1986: The first open heart
unitized plastic sheet oxygenator for open heart surgery. repairs of ventricular septal defect, atrioventricular communis,
Diseases of the Chest 32, 615–25. and tetralogy of Fallot using extracorporeal circulation by cross
Jaques, L.B. 1978: Addendum: the discovery of heparin. Seminars in circulation: a 30 year follow up. Annals of Thoracic Surgery
Thrombosis and Hemostasis 4, 350–3. 41, 4–21.
Jongbloed, J. 1949: The mechanical heart/lung system. Surgery, McLean, J. 1959: The discovery of heparin. Circulation XIX, 75–78.
Gynecology and Obstetrics 89, 684–91. Mustard, W.T., Thomson, J.A. 1957: Clinical experience with the
Kay, E.B., Zimmerman, H.A., Berne, R.M. et al. 1956: Certain clinical artificial heart–lung preparation. Journal of the Canadian
aspects in the use of the pump oxygenator. Journal of the Medical Association 76, 265–9.
American Medical Association 162, 639–41. Mustard, W.T., Chute, A.L., Keith, J.D. et al. 1954: A surgical
Kirklin, J.W., Dushane, J.W., Patrick, R.T. et al. 1955: Intracardiac approach to transposition of the great vessels with
surgery with the aid of a mechanical pump oxygenator system extracorporeal circuit. Surgery 36, 39–51.
(Gibbon type): report of eight cases. Proceedings of Staff Naef, A.P. 1990: The story of thoracic surgery. Toronto: Hografe &
Meetings of the Mayo Clinic 30, 201–7. Huber, 113–19.
Kolff, W.J., Balzer, R. 1955: The artificial coil lung. Transactions Rygg, H., Kyvsgaard, E. 1956: A disposable polyethylene oxygenator
of the American Society for Artificial Internal Organs 1, system applied in the heart/lung machine. Acta Chirurgica
39–42. Scandinavica 112, 433–7.
Kolff, W.J., Berk, H.T.J. 1944: Artificial kidney: dialyser with a great Sealy, W.C., Brown, I.W., Young, W.G. 1958: A report on the use of
area. Acta Medica Scandinavica 117, 121–34. both extracorporeal circulation and hypothermia for open-heart
Lande, A.J., Dos, S.J., Carlson, R.G. et al. 1967: A new membrane surgery. Annals of Surgery 147, 603–13.
oxygenator–dialyser. Surgical Clinics of North America 47, Westaby, S., Bosher, C. 1997: Landmarks in cardiac surgery. Oxford:
1461–70. ISIS Medical Media.
Lillehei, C.W. 1962: Hemodilution perfusion for open heart surgery. Zuhdi, N., McCollough, B., Carey, J. et al. 1961a: Hypothermic
Use of low molecular weight dextran and five per cent dextrose. perfusion for open heart surgical procedures – report of the use
Surgery 52, 30–31. of a heart–lung machine primed with five per cent dextrose in
Lillehei, C.W. 2000: Historical development of cardiopulmonary water inducing hemodilution. J Int Coll Surg 35, 319–26.
bypass in Minnesota. In: G.P. Gravlee et al. (eds), Zuhdi, N., McCollough, B., Carey, J. et al. 1961b: Double helical
Cardiopulmonary bypass: principles and practice reservoir heart–lung machine designed for hypothermic
(second edition). Baltimore, MD: Lippincott Williams & perfusion primed with five per cent glucose in water inducing
Wilkins, 3–21. hemodilution. Archives of Surgery 82, 320–5.
26. 2
Design and principles of the extracorporeal circuit
MEDTRONIC, INC., A MANUFACTURER OF TECHNOLOGIES FOR EXTRACORPOREAL CIRCULATION
History of cardiopulmonary bypass 7 Heat exchangers 14
Bubble oxygenators 8 Tubing 15
Membrane oxygenators 8 Myocardial protection 15
Components of the extracorporeal circuit 9 Biocompatibility 16
Pumps 9 Adequacy of perfusion 21
Venous reservoir 12 Acknowledgements 21
Cardiotomy reservoirs 13 References 21
the extracorporeal circuit are adequately perfused
KEY POINTS with oxygenated blood by continual monitoring of
blood flow rate, perfusion pressure, acid/base
state, oxygen consumption, coagulation and renal
• The essential components of the clinical
function.
extracorporeal circuit are a pump (artificial heart),
an oxygenator (artificial lung), a reservoir and the
tubing to connect these devices, although systems
are now emerging without traditional reservoirs.
HISTORY OF CARDIOPULMONARY BYPASS
• Additional components include a heat exchanger,
a system for myocardial protection, and gas and
emboli filters. Secondary suction circuits may be The first proposal for artificial circulation was put for-
added for salvaging shed blood, and venting the ward by Le Gallois in 1812 when he perfused rabbit
heart. brains through carotid arteries. Between 1848 and 1853
• The current generation of membrane oxygenators Brown Sequard showed that dark venous blood, when
incorporating reservoirs and heat exchangers exposed to air and shaken, turned bright red. He further
provide safety, efficacy and ease of use. demonstrated the feasability of perfusing isolated brain
• Centrifugal pumps are compact, durable, easy to specimens with this ‘arterialized’ blood. The first bubble
set up and cause minimal haemolysis compared oxygenator, utilizing the same principle of mixing venous
with roller pumps. While their cost is certainly blood with air, was assembled by Shroder in 1882. And
higher than a simple length of roller pump tubing, then, two years later, von Frey and Gruber created the first
it may be more than offset by savings in ventilatory membrane oxygenator, in which the direct blood–air
and ICU time, as well as overall hospital stay. interface of the bubbler design was avoided.
• A body of published evidence, as well as extensive In 1900, Howell and colleagues discovered the anti-
clinical experience by surgeons and perfusionists, coagulant properties of heparin. Without the risk of cata-
supports the value of heparin-based biosurfaces strophic clotting within the bypass circuit, it was now
for thrombo-resistance and biocompatibility possible to expose the blood to extended periods of
during extracorporeal circulation. extracorporeal circulation.
• It is the responsibility of the perfusionist to The first clinical application of extracorporeal circula-
ensure that the organs of the body supported by tion was performed by Dr John Gibbon, Massachusetts
27. 8 Design and principles of the extracorporeal circuit
Table 2.1 Developmental history of oxygenators
Non-membrane oxygenators
1937 Gibbon Blood filter – pulmonary embolus
1951 Dennis/Bjork Rotating screen and cardiopulmonary bypass rotating disk
1955 Lillehei/DeWall First bubble oxygenator with helix reservoir
1956 Kay/Cross Refind disk oxygenator for up to 4000 mL of venous blood
1956 Rygg/Kyvsgaard First disposable plastic bag oxygenator, Polystan (Rygg Bag)
1962 Cooley/Beall Proposed use of commercially available disposable bubble oxygenators
(Travenol Bag)
1966 DeWall/Najafe/Roden First disposable hard shell oxygenator (polycarbonate) with built-in heat
exchanger (Bentley Labs)
Membrane oxygenators
1955 Kolff/Balzfer Oxygenated blood through polyethylene membrane (animals)
1956 Kolff First coiled polyethylene tube oxygenator
1958 Clowes First to test Teflon as membrane plate oxygenator
1968 Lande Methyl silicone folded plate membrane oxygenator (Lande/Edwards)
1969 Pierce Co-polymer of dimethyl siloxan and polycarbonate
1969 Pierce Pierce-GE
1971 Kolobow Silicone rubber reinforced by nylon mesh rolled or coiled (SciMed–Kolobow)
1972 Eiseman/Spencer Expanded (Teflon) membrane sheets (Travenol/TMO)
1975 Travenol Labs Polypropylene (expanded) plate or sheets (TMO)
1985 J& J Cardiopulmonary First hollowfibre polypropylene oxygenator (Maxima)
General Hospital who, in 1953, successfully repaired an into the bubble chamber. The early Bentley model has
atrial septal defect in a young female. Despite subsequent the heat exchanger located within the arterial reservoir.
setbacks, Dr C Walton Lillehei of the University of Bubble oxygenators are efficient and easy to use. Unfor-
Minnesota and several others persevered in further tunately, the nature of the foaming/defoaming process
developing the techniques and equipment, with Lillehei causes significant haemolysis, which becomes clinically
using the first bubble oxygenator in 1955. significant after only a few hours. Bubble oxygenators also
The bubble oxygenator, first developed by Rygg, was present a higher risk of micro- and macro-air embolism:
produced commercially by 1956. The years since have seen the defoaming process is imperfect, and inadvertent
myriad refinements and improvements in oxygenator and emptying of the arterial reservoir can lead to massive
other component designs, which unlike the early systems amounts of air being pumped directly to the patient, at
are now completely disposable. A brief history of the least when roller pumps are used. Further, because of the
development of oxygenators is summarized in Table 2.1. bubbling process, it is not considered safe to blend oxy-
gen with air (since nitrogen bubbles would be so much
less soluble) making independent control of pO2 and
BUBBLE OXYGENATORS
pCO2 impossible. This would also necessitate the mixing
of small amounts of carbon dioxide with the oxygen to
Bubble oxygenators were the first design to be commer- prevent the pCO2 from falling too far. For these reasons,
cially available in completely disposable form, and were bubblers are rarely used today. Several safe, efficient
in wide use throughout the world for more than 46 years. membrane oxygenators currently dominate the market.
A ‘bubbler’ usually consists of an integrated design, incorp-
orating the oxygenator, heat exchanger, arterial reservoir
MEMBRANE OXYGENATORS
and cardiotomy filter in one unit. The unit functions by
passing incoming venous blood over a perforated or
porous sparger plate, through which oxygen is passed, Membrane oxygenators of various designs have been
turning the venous blood into a foam of variously sized used sporadically since the mid-1950s, but it was not
bubbles. As oxygen diffuses across the bubble surfaces until 19 years ago that relatively low-prime volume, easy-
into the blood, and conversely, as excess carbon dioxide to-use units became commercially available. In the mem-
diffuses from the blood into the bubbles, the blood is brane oxygenator, the ventilating gas is separated from the
arterialized. The blood is then passed through a silicone- blood by a semi-permeable membrane fabricated from
based defoaming medium, collects in an arterial reser- polypropylene, or in one case, silicone rubber. Unlike bub-
voir section and is returned to the patient. The heat ble oxygenators, there is no direct contact between the
exchanger in most bubble oxygenators was incorporated blood and ventilating gas. Gas exchange is accomplished
