British Journal of Plastic Surgery (1990), 43,64M44 0 1990 The Trustees of British Association of Plastic Surgeons

0007-1226/90/0043SO641/S10.00

Invited paper

Organisation of a microsurgical laboratory

C. J. GREEN

Section of Surgical Research, MRC Clinical Research Centre, Northwick Park Hospital, Harrow, Middlesex

Identifying the local need

Any clinical department contemplating setting up a microsurgical laboratory should be very clear what it wants to achieve and must realise that it is not to be undertaken lightly. The Animal (Scientific Procedures) Act 1986 specifically allows medically qualified personnel to use animals for the acquisi- tion of microsurgical skills in a way in which no other surgery can be practised or learned in the UK. Most techniques have to be learned on people. It is therefore taken as read by Government that basic microsurgery can only be learned initially on animals in a laboratory setting. The very opposite view is held by the animal rights lobby. The bombers are not going to go away. The facility will need to be secure. The first question to be answered then is whether the hospital wants to be involved in animal experimentation. Will the perceived benefits to the surgeons in training outweigh the risks and possible loss of local public support? If the answer is in the affirmative, the next question to address is whether the facility will satisfy the Home Office inspectorate. Two licences are now required : in one, the project licence, the laboratory director must state the objectives of the microsurg- ical programme and give details of the techniques to be used; in the other, the personal licence, each surgeon has to apply as an individual before he or she is allowed to work on animals. Licences will only be granted if the physical facilities and the people staffing them are suitable.

Thereafter, the questions are more or less self- evident. What are the objectives? Is the laboratory simply to be a practice facility in which young surgeons first go away to specialist courses to gain basic microsurgical skills and then use their own laboratory for practice and reinforcement? Or does the department have more ambitious plans involv- ing postgraduate education, research and pursuit

of higher surgical degrees? For what it is worth, my own view is that we are steadily falling behind our European Community colleagues in organisation of postgraduate education in reconstructive surgery and that at least six centres of excellence need to be established in the UK. These should be properly funded University departments, preferably with Chair status, and with basic scientists involved in relevant research programmes alongside clinical colleagues including plastic, orthopaedic, maxillo- facial and burns specialists.

The following description of laboratory organi- sation is based on the assumption that a composite programme of microsurgical training on animals, cadaver dissections in the mortuary and high quality research is required. The number of these recom- mendations which will prove acceptable or are discarded will depend on the perceived local need and the level of funding available.

Laboratory organisation

Personnel

By far the most important asset in a laboratory is skilled technical staff, able, motivated and willing to teach a stream of young surgeons under training passing through the department. They provide the essential continuity to a rolling programme of research. They must acquire excellence in micro- surgery, a range of small animal operations, animal anaesthesia, postoperative care of animals, animal handling and husbandry, X-radiography, physio- logical monitoring, autopsy and histological proc- essing, and maintenance of a computer data base. In other words, the job needs high calibre people but, since so many of these tasks need training “in- house”, it makes little difference in our experience what their previous education or training com- prised.

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Animals A small unit is best advised to buy in its rodents from commercial sources as required rather than attempt to breed animals on a small scale them- selves. It is imperative to work with animals in excellent health, preferably those freshly issued from barrier-maintained pathogen-free colonies (SPF or Category 4 in commercial terms). Cheap cast-offs are not cost-effective if they die in the middle of an operation. For training purposes, adult (12-week-old) outbred Sprague-Dawley rats are ideal and the least expensive to buy. However, for research purposes, in-bred strains which should be genetically histocompatible are usually required. Tissues can then be transplanted either as isografts if an immune response is to be avoided, or as allografts if the experiment entails a study of immune events. There are many in-bred strains available but we favour the Lewis, Dark Agouti (DA), AS and PVG strains as they provide a range of incompatibilities from moderate to very strong. Again it is best to pay specialist technicians to look after these animals properly rather than attempt to do so on a part-time amateurish basis. As already indicated, the Home Office inspectorate will, in any case, insist on high standards before allowing a project licence to be issued.

Microscopes and loupes The cost of operating microscopes is now so high that it is often difficult to decide whether to buy a second-hand possibly outdated instrument but with more sophisticated facilities such as viewing tubes, video camera facilities and so on, or go for a brand new machine. Non-motorised, hand-operated mi- croscopes on a bench stand are adequate for learning basic microsurgical technique on rodents. Whatever happens, though, it does not pay to make do with inappropriate optics. Operator fatigue through poor lenses and insufficient illumination has to be the single most important factor in deterring learners from continuing with microsur- gery. If it is anticipated that the laboratory is going to be involved, in future, in training large numbers of surgeons then it should try to reproduce clinical conditions as closely as possible and purchase a double-headed diploscope with foot-operated con- trols for motorised zoom focus and magnification. A mobile stand on a stable platform is most convenient where laboratory space is at a premium. Optically, the depth of focus and breadth of field

must be comfortable even at high magnification and this is best achieved with 1Oor 12.5 x eyepieces and 175 or 200 mm objective lenses. A range of magnification from 4 x to 25 x is perfectly adequate for this work. Binocular tubes with focal lengths (f) of 125 mm, 160 mm or 180 mm are suitable. Illumination is best achieved by fibreoptic trans- mitted light. The technical/nursing staff must be trained in the care of these expensive machines,

It would be unfair to make comparisons of different commercial makes for laboratory use. Our experience with the Zeiss OPMI 6c microscopes on a Universal stand and the Wild Leitz on its own stand has been equally good, and others report that Week microscopes are excellent. They are all expensive to purchase new.

Teaching is undoubtedly greatly assisted by using diploscopes with video-camera attachments. Mod- ern Hitachi, Sony and Panasonic cameras become progressively more miniaturised and lighter so that they are less of a burden on the microscope’s motor clutch.

Magnifying loupes are often more convenient than the microscope for preliminary dissection and microsurgery of larger vessels (e.g. aorta of rats). A simple model with an elasticated headband (Keeler, Binomag) gives a magnification of 1.8 x whilst the Zeiss or Keeler loupes ( x 2 or x 4) with telescopic lenses are excellent.

Instruments Depending on the numbers of surgeons using the facility, several basic sets should be contained in sterilisable, autoclavable instrument cases. The instruments must be purchased new. Far too many surgeons are trying to learn microsurgery on rats using discarded theatre instruments with distorted bent teeth or jaws. If it isnot possible for each surgeon to have and be responsible for their own set (with financial penalties for careless use) then the instruments should be carefully looked after by the technician in charge. Again early training in these essentials is an investment over the years. A suggested basic set should consist of: three pairs of microsurgical forceps, two vessel dilator forceps, one non-ratchet microsurgical needle holder, dis- secting scissors, adventitia scissors, Vanna’s scis- sors, vessel clamps (two single for artery and vein and one approximating double clamp) and either bipolar coagulators or disposable battery-driven coagulators which can, in rats, be used repeatedly. For preparation of the animals, good electric

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clippers are essential. Well-designed operating tables and cork operating boards complete the list of essentials.

Microsurgical sutures A range of monofilament nylon sutures (8/O to 1 l/ 0) should be held. Boxes of 48 non-sterilised 10/O sutures are available for laboratory use (Ethicon Ltd) and outdated theatre sutures are perfectly acceptable for training purposes. Different needle lengths and alternative suture materials (e.g. pro- lene) should be stocked to allow trainees to assess their preferences for themselves.

Training exercises Initial practice in handling microsurgical instru- ments and sutures as well as in adjusting the operating microscope can be gained whilst “sutur- ing” incisions in fine silastic or latex rubber sheeting or joining together either fine latex rubber tubing or lengths of rabbit aorta which have been removed from the animal and stored until required. A relatively large suture and needle (S/O monofilament nylon) is most suitable at this stage. These exercises are, however, very limited in value and it is worth spending no more than a morning on them before moving on to the living anaesthetised rat.

Rats provide a complete anatomical range of sites for learning microvascular, peripheral nerve, vas deferens and oviduct anastomotic techniques. The beginner is well advised to master the range of vascular exercises before moving on to techniques such as oviduct, for the very good reason that post- anastomotic blood flow provides such an obvious and vivid index of success or failure. If a small vessel such as a femoral (1 .O mm) or even superficial epigastric artery (0.330.4 mm) can be anastomosed and remain patent, the surgeon should have no problems with nerves or other conduits.

The most valuable site for vascular access is the femoral triangle. Exposure of the femoral artery and veins with their main tributaries, the superficial epigastric vessels, provides ideal vessels for end-to- end, end-to-side and interpositional vein graft anastomoses to be learned. In the neck, the carotid artery and jugular vein are excellent vessels for further exercises such as arterial end-to-side anas- tomosis, for creating vascular loops and as recipi- ents of organs such as kidney or heart. Within 28 hours of practice time the average beginner can usually master the femoral triangle exercises. By the end of 40 hours they can usually cope with more difficult tasks such as orthotopic groin flaps,

heterotopic cardiac grafts in the neck or renal grafts anastomosed end-to-end to the renal vessels. The sciatic nerve is too small to provide an ideal exercise for simulating clinical peripheral nerve repair but it is the best available. As an exercise to mimic repair of oviducts in women, the anterior horns of the rat’s bicornuate uterus are quite good. Once these exercises have been completed and repeated at least five times to the tutor’s satisfaction, the trainee should learn to do them working in a simulated cavity through a solid plastic bridge and 1.5 cm diameter hole. Later on, they should work in gloves and gradually work up to aseptic tech- nique. The whole emphasis in training should be on gradual step-by-step progress in a programmed fashion. Forty hours of training packed into a week of concentrated effort yields better results than 12 months of occasional visits to the laboratory for an afternoon each week.

Ready access to human cadaver material is also needed in the training programme. Microsurgical training in rats has such obvious deficiencies that any surgeons seriously considering making a careei in reconstructive surgery should complement their animal work with regular dissections to familiarise themselves with their future anatomical targets. Post-mortem vascular dye and angiographic tech- niques which will assist in identifying the vascula- ture to difficult flaps or extremities are useful techniques to learn for cadaver examination.

Postgraduate research

If the laboratory is to make a substantial contribu- tion to clinical research, it is essential that surgeons contemplating time out from their clinical pro- gramme realise that 18 months, and preferably 24 months, of full-time commitment is required. Even then, they will only succeed if they collaborate with high quality basic scientists such as immunologists, biochemists, physiologists (vascular and neuro-). molecular biologists and pathologists with good access to histopathology and electron microscopy. This demands access to modern equipment. X- radiography, angiography, gamma-camera scinti- graphy, spectrophotometry, gas liquid chromato- graphy, high pressure liquid chromatography, image analysis, fluorimetry, tissue culture hoods, cell counters, high speed centrifuges and an electron microscope should be on any short-list in a modern laboratory.

A “library” of microsurgical models available for research should also be held within the department.

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This is only possible in the presence of excellent technical staff. As examples, miniature models which are useful include transplantation of heart, kidney, liver, pancreas, small bowel, single lung, heart-lung, spleen, stomach, ovary, testicle, free flaps, whole joints and whole limb, all of which can be carried out in rats or rabbits.

Money must be available for research fellowships (18-24 months). Some should also be earmarked for travel bursaries so that the surgeons can go to several meetings in the UK and overseas to present their work. Medical research at an international level is a highly competitive business and the best experimental data in the world are worthless unless they are presented verbally at quality meetings and written up as soon as completed. Secretarial help, library searches, computerised data, word proces- sors and an insistent nudge from his supervisor to get on and publish before the research fellow plunges back into clinical practice, are all essential to success.

Overall conclusions

Once surgeons get over the culture shock of laboratory life and realise that most experiments fail in a way which would be catastrophic in surgical practice, they enjoy themselves and gain enor- mously from the experience. Their talents and immense capacity for hard work should be exploited more fully. Each of the departments in the UK should have its own practice microsurgical labora- tory. At least six of these should develop strong postgraduate research programmes and acquire the necessary funding to do so.

The Author

Dr Colin Green, Director, Section of Surgical Research, MRC Clinical Research Centre, Watford Road, Harrow, Middlesex HA1 3UJ.

Requests for reprints to the author.