1278

In one study16 a single shock of 240 J ruptured thecoronary sinus of a dog-but in all the other dogs evenrepeated shocks of 200 J caused no such damage.The high success rate of endocavitary ablation and

the ease with which it can be repeated (if necessary)means that endocavitary ablation will be used

increasingly. This being so, we need to know muchmore about how the ablation is achieved. We also needcatheters that have been designed to withstand the highenergies; possibly the electrodes should be smaller andpositioned along one edge, rather than a series of

complete rings, so that the discharge can be directedrather than dissipated into the blood pool. Finallyalternative approaches must be considered. Electro-cautery, via modern flexible catheters, and the use oflasers" offer the possibility of controlled and limiteddestruction of selected areas so that tachycardia is

prevented while conduction continues unimpaired.

PATHOLOGY TESTS—TOO MUCH OF A GOODTHING

IT is not only history that repeats itself. The same

laboratory investigations on the same patients are repeatedwith monotonous regularity and this practice is one of themain factors in the increased workload of hospitallaboratories. Each year in England and Wales haematologyrequests rise by 7—14%, microbiology tests by 6-10%, andchemical pathology tests by 10-17%. (There was an apparentfall in 1974 coincident with the reorganisation of the healthservices, but this was undoubtedly due to failure to collectproper data rather than to an unexpected benefit from thatexercise.) At the same time in England the number of requestsper patient has increased substantially.’ About 10% of thelaboratory workload originates from general practitioners.Clinical chemistry and haematology laboratories have

accepted this increased workload philosophically because ofthe availability of automated equipment that can handle largenumbers of samples. Microbiologists, however, have not hadthe benefit of such equipment.New therapies such as organ transplantation and intensive

cytotoxic therapy for neoplasia bring with them a largeincrease in laboratory work but the general increase inworkload is common to hospitals without such units. An800-bed district general hospital can expect to processbetween 1000 and 1500 samples each day in its laboratories.On Mondays half to two-thirds of in-patients will have bloodsamples taken to be distributed among the laboratories. AnIrish survey of 371 patients discharged from medical wards2showed that routine blood counts seldom affected

management. More than half the tests performed were repeattests, many of them for those whose initial results werenormal. Indeed 78% of the repeat tests provided no new ordifferent information.

16 Brodman R, Fisher JD. Technique for ablation of anomalous conduction using catheterplaced in coronary sinus: canine studies. Circulation 1982; 66: II-217.

17 Narula OS, Bharati S, Chan MC, Embi AA, Lev M Laser micro transection of the Hisbundle a pervenous catheter technique. JACC 1984, 3: 537.

I Fleming PR, Zilva JF. Work-loads in chemical pathology: too many tests? HealthTrends 1981, 13: 46-49

2. Ajeel NAH, McCormick J. The use of routine blood counts. Irish Med J 1984, 77:100-01.

The reasons for the flood of laboratory investigations arecomplex. Firstly, the attitude of the consultant is crucial insetting the climate. If recent data are required on each wardround and if junior staff are neither rebuked for unnecessaryinvestigations nor questioned about the rationale for an

investigation, then there is nothing to discourage irrelevantor repetitious testing. Secondly, the laboratories have beenmade to take on a screening role rather than providing adiagnostic service. This is particularly so in clinical chemistrywhere the pressure of equipment manufacturers has, in thepast, dictated the pattern of investigations performed. One ofthe newer automated blood counters provides fifteen piecesof information on a routine blood count, at least four of whichhave not, as yet, been shown to have any relevance to clinicalmedicine. Some of the newer machines, however, allowgreater discretion in the performance of tests and permit onlythose tests which are relevant to be selected. Thirdly, ingeneral, organisation of investigations is left to the most

junior member of the medical team. It is all too easy to fill outa large number of forms in the early evening for the

phlebotomist to pick up in the morning. In many hospitalsthe doctor no longer even takes the blood sample. Finally,there is no pressure on the consultant to rationalise his patternof investigation. The facilities of the service departments areall at his or her behest. It all seems to be "for free".A requirement by the laboratory that all out-of-hours

requests by house officers in a London hospital be screenedby their own registrars resulted in a halving of the number oftests and a very considerable saving in fees paid to techniciansfor after-hours work. Perhaps the allocation of budgets tomedical teams so that they will "buy" their investigationsmay help. But, other than a paper exercise, this may bedifficult to implement within the present organisation ofNational Health Service hospitals. Useful savings can beachieved only if there is a fall in workload, of at least 20%,such as to allow a reduction in staff numbers. Small decline in

specimen numbers will merely save the cost of syringes,needles, specimen bottles, and diluent. A large reduction inworkload is possible only with much more discriminating useof laboratories by clinicians. One hopes that it could beachieved simply by the practice of good medicine. Butfinancial pressures may help to sharpen the mind.

TREATMENT OF LEAD POISONING IN CHILDREN

IN management of lead poisoning one of the difficultdecisions concerns chelation therapy. Such treatments arenot without hazard, and in young children, the most

vulnerable section of the population to the adverse effects oflead, it is particularly important that the right decision ismade.’ Blood lead concentrations of less than 30 µg/dl areusually classed as within normal limits, although the range20-30 µg/dl probably indicates some degree of over-

exposure ; and when the blood lead exceeds 70 jLtg/dl there isgeneral agreement on the need for intervention. Most of thedispute about treatment is centred on the narrow territorybetween these figures. Clearly, the first course is to removethe exposed person from the source of exposure. Then comesthe decision for or against chelation therapy (which has in thepast been combined with haemodialysis).2

1. Center for Disease Control. Preventing lead poisoning in young children. Atlanta,Georgia: U S. Department of Health, Education and Welfare, 1978.

2 Pedersen RS. Lead poisoning treated with haemodialysis Scand J Urol Nephrol 1978;12: 189-90.