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SHORT WAVES AND SHORT-WAVETHERAPY

THE CONGRESS IN RETROSPECT *

THE scope of the International Short-Wave Congresswas a very broad one. There were papers on allaspects of the subject : production, transmission, andreception of short waves ; absorption by chemicaland biological systems ; the distribution of heating inheterogeneous bodies ; " specific " physical, chemical,and biological effects ; and therapeutic applications.While it is clearly impossible for any one person tobe fully acquainted with all these branches, it is alsocertain that there were very few papers presented,even among the purely physical ones, that could

legitimately be ignored by the medical man. It wasindeed one of the objects of the congress, as Prof.THIRRING emphasised in his address during the openingceremony, to enable some of the fundamental medical

questions-mode of action of short waves, measure-ment of " dosage " in short-wave therapy-to bediscussed at joint sessions of the medical, physical,and biological sections. The discussion has not,perhaps, brought us very much nearer to a solutionof either of these problems ; but it will have beeninvaluable if it has only helped a few short-wavephysicists to think biologically, and a few short-wave practitioners to understand the value and thelimitations of a purely physical consideration of theirproblems.PRODUCTION AND APPLICATION OF DECIMETRE WAVES

The interest of the papers on the production ofshort waves, from the medical point of view, lies inthe fact that they dealt predominantly with centimetreand decimetre waves. The significance of this is clearenough : these very short waves are becoming ofincreasing commercial value, and resources are beingused for their investigation which would never beavailable for any purely medical purpose. It is how-ever inevitable that as soon as they can be producedat sufficiently high intensity these waves will beused therapeutically, and it is important that thenew difficulties which their use will involve should be

anticipated before they are widely and irresponsiblyapplied. Preliminary papers on the therapeutic effectsof 80 cm. waves were indeed presented at the congressby BRUNNER-ORNSTEIN (Vienna) and DENIER (LaTour-du-Pin).With the use of higher frequencies, the condenser-

field method will become less important and will bereplaced by a quasi-optical technique-true

" irradia-tion," in which the properties of the tissue irradiatedwill be more conveniently expressed by its refractiveindex and optical absorption coefficient than by itsconductivity and dielectric constant. The possibilitiesof such methods are being worked out by PATZOLD,of the Siemens’s research laboratories, Erlangen.Patzold has measured the Halbzuertsschicht for varioussalt solutions-that is, the depth of solution whichis sufficient to reduce the intensity of an incident rayto half its initial value-at a wave-length of 430 cm.,finding values of 1.9-20 cm. for the conductivity range10-2-10-4 ohm.-l cm.-l, and is making further measure-,ments at À85 cm. Such measurements are of the

greatest importance, since the values of refractiveindex and absorption coefficient (or dielectric constantand conductivity-the constants determining heat-

* The first International Congress for Short Waves in Physics,Biology, and Medicine was held in Vienna in July. A reportfrom our Vienna correspondent appeared in THE LANCET ofAugust 14th.

production) measured at longer wave-lengths are nolonger valid-partly because of the increasing con-ductivity of water as the frequency is increased. Newabsorption measurements on water, mentioned byFALKENHAGEN and by ESAU, show that the maximumabsorption coefficient occurs at a wave-length ofabout 2 cm.

SELECTIVE HEATING

At the wave-lengths at present in general use, thefactors determining distribution of heat in tissueshave long been understood theoretically, but thematter is in practice so complex that the properchoice of wave-length for selective heating of a certainregion, and the rough estimation of the degree ofselectivity, have hitherto been impossible ; clinicalprocedure has necessarily been empirical, and it isonly recently that reliable values of the relevantconstants for different tissues have been obtained. Itis a result of the cellular structure of tissues that at

very low frequencies they have high apparent dielectricconstants and comparatively low conductivities ; at

higher frequencies, the conductivity increases and thedielectric constant decreases, the manner in whichthis transition occurs depending on the type andeven on the physiological condition of the tissue.RAJEWSKY (Frankfurt a. M.) reported measurementsof the conductivity of a number of tissues at differentwave-lengths, while OsswALD (Erlangen) determinedboth conductivity and dielectric constant, and pointedout that for any reliable calculation of the mostsuitable wave-length for selective heating of a giventissue, complete data of this type-" dispersioncurves " for all the tissues concerned-must be avail-able. Osswald draws the important conclusion fromhis new data, that for the greatest possible reductionof heating of fat and the greatest selective heating ofmuscle, the following two conditions must be chosen :(1) the field must be made as homogeneous as possibleby the use of a wide gap between electrodes and skin,and (2) the shortest available wave-length-1 m. orless-must be used. In general a selective heating ofother tissues, excluding fat, will hardly be possible,but it should be possible when very short waves areavailable-e.g., about 40 cm.-to heat the pure bodyfluids (bile, urine, &c.) without any considerableheating of the neighbouring tissues.The relative decrease in the heating of fat at shorter

wave-lengths, predicted from Osswald’s results, hasactually been observed by PATZOLD, ESAU, andAHRENS, who measured the rise of temperature oflayers of muscle and fat placed in series in thecondenser field. At X6 m., the fat was heatedmore, and at 1 m. less, than the muscle.

SPECIFIC (NON-THERMAL) EFFECTSOn the scientific side, it cannot be said that any

particularly significant new experimental data onnon-thermal effects were presented ; a number ofpapers dealt with the effects of the condenser fieldon bacteria, moulds, viruses, &c., and the best ofthese from an experimental point of view-to expressa personal opinion-reported monotonously negativeresults. Nevertheless a certain theoretical claritywas introduced in the paper of KRASNY-ERGEN, whodescribed the specific mechanical and electrical effectsof the alternating or rotating electric field on hetero-geneous systems-effects which would not, however,be sharply frequency-specific, and which do not

provide any starting-point for a theory of specificchemical effects. Such a theory would indeed besuperfluous until satisfactory experimental evidencefor a chemical action of the condenser field has beenproduced. In an interesting paper, K6NIGER (Brno)

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discussed the types of chemical reaction system whichmight be used in a search for such effects.

TREATMENT

"law Intensity" Tcpy.—Meanwhile, the thera-peutic effects of exceedingly low intensities of ultra-high frequency energy continue to be investigated,above all by LIEBESNY (Vienna ; administrative

president of the medical section of the Congress), whodescribed the favourable effects of " athermal "treatment on furuncles, carbuncles, lung abscesses,and certain tuberculous lesions; MELLER, Löwy,and FUCHS obtained equally satisfactory results in thetreatment of inflammations of the middle ear, andHAUSMANN, RIEGER, and RABINOWITSCH describedthe results obtained in the Viennese ophthalmologicalclinics. .

The question of the relative effectiveness of largeand small intensities in different pathological con-ditions arose very frequently during the medicalsessions. MEYER (Paris) advocated the use of very smalldoses in treatment of angina pectoris, and emphasisedthe necessity for a very careful clinical selection ofcases, although SIEGEN (Bad Kudowa), who also

reported excellent results in various forms of angina,apparently used rather high intensities. URBACH(Prague) claimed tp have confirmed the value of

Liebesny’s methods for a large number of acute

inflammatory states, with a few exceptions, while

emphasising that chronic conditions, especially thosewhich in general react favourably to other forms ofheat treatment, require larger (thermal) doses. Severalcontributors to the discussion following KORB’S

(Erlangen) -paper on the technique of gynaecologicalshort-wave therapy-RICHTER, SCHOLTZ, RIEMER,ROTHWIEN, WOLF-agreed on the value of very smalldoses in acute inflammatory conditions, and of largerdoses in chronic cases ; indeed the same opinion wasrepeatedly expressed in other papers.The Problem of Dòs’lge jMesMree.—The question

of " athermal " treatment suggests immediately theproblem of dosage : on what grounds do the advocatesof weak dosage assert that the temperature rise inthe patient is negligible ? The usual criterion of

dosage is a subjective one, and LIEBESNY himselfpointed to its extreme unreliability. A chronicarthritic, for example, was repeatedly given a dosewhich led to a rise of 3°-4° C. in skin temperature,without his experiencing any sensation of warmth,and in other cases a rise of as much as 8° C. wasaccompanied only by a " pleasant " warmth. The

rapid objective measurement of dosage is, however,very difficult, and most of the new methods suggestedat the Congress are open to some objection, or are toocomplicated for general use. WENK (Erlangen)described a method, accurate to 5 per cent., in whichthe resonance curve of the patient’s circuit is imitatedin a substituted circuit consisting of condensers andfixed resistance, the loss of ’energy in the resistancebeing then read off directly in watts. The descriptionof a second method, more rapid but less accurate

(15 per cent.), lacks essential details. MITTELMANN(Vienna) measures the current passing during treat-ment with a thermocross, and the effective resistanceof the circuit with a secondary transmitter and valve.voltmeter. SCHWARZ suggests that for measurementof the true voltage across the patient, small electro-meter electrodes might be mounted in the condenserplates.

Short-wave Therapy in General.-ScHLIEPHAKE, inhis admirably restrained introductory paper, empha-sised the dangers of " automatic " use of short-wavetherapy in the hands of sisters and bath supervisors ;

he then mentioned the comparatively restrictedpathological fields in which it has become definitelyestablished as a therapeutic agency :

(1) Pyogehié skin inflammations, empyema, of theaccessory nasal cavities, pleurisy, and lung abscesses. Thecorrect dosage, still entirely a matter of guesswork, isessential, over-dosage being dangerous and under-dosageineffective. The dosage can be gradually increased duringthe course of treatment.

(2) Various ophthalmological conditions, such as inflam-mation of lacrymal duct, iritis, and retrobulbar neuritis.

(3) Chronic rheumatic arthritis. Here general treat-ment with large doses is usually necessary ; the improve-ment is often considerably delayed; perhaps for severalweeks after treatment has been stopped. The most severecases of polyarthritis may show astonishing improvement.The treatment of circulatory disturbances, including

intermittent claudication, frost-bite, and thrombo-angiitis obliterans, was several times referred to,somewhat uncritically, and WOLF (New York) pointedout that a heat therapy would only be expected to beof value in cases where the capillaries have notsuffered organic damage. For technical simplicity,KOWARSCHIK (Vienna) recommends the use of thesolenoidal field in such cases, and for all localtreatment of limbs.

CoLARizi (Rome) found that the early treatment ofpoliomyelitis gave most encouraging results, andcould be applied without danger even to the smallestchildren ; MERDINGER (Cernauti) confirmed this

report as a result of his experience in epidemics ofpoliomyelitis in Bessarabia. WOLF mentioned experi-ments in which apes injected with the virus were

given fever doses of high-frequency energy; mostof them died of pneumonia.

Fucrrs (Vienna) discussed the possible value andtechnique of combined Rontgen and short-wavetreatment, and ZIMMER (Berlin) suggested that thehyperaemia resulting from the latter may be respon.sible for the increased effect of X rays reported byseveral previous workers. IREDELL (London) describedtwo cases, one of malignant disease and one of actino-mycosis, which suggested that the favourable effectsof radium were also somewhat increased by simul.taneous short-wave treatment. Biological experimentson the production of mutations by X rays (PrcKHAN,TimOFIEF-RESSOVSKY ’ and ZIMMER) have so farfailed to show any

" sensitisation " by the high-frequency field.

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PARIS

(FROM OUR OWN CORRESPONDENT)

POMARET’S LAW ONCE MORE

THOSE who have not seen earlier references toPomaret’s law in these columns may note thatM. Pomaret was once a member of the French Govern-ment and is now a member of Parliament. His law,which by the way is only in the draft stage, concernsall the liberal professions, not only that of medicine.Its guiding principle is that employment must befound for the young by the compulsory retirementof their seniors at 65. The outcry against the proposalcame in part from the young, inspired no doubt bychivalrous emotions as well as by the fact that evenafter 65 parents may be materially useful to theiroffspring. M. Pomaret was invited this summer toface the music, and he did so to such good purposeand with such good grace that there is every prospectof his original scheme being decently interred and anew one evolved under happier auspices. On June 17thhe met the representatives of the Confederation