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The History of Anaesthesia at Dräger

Volume I

2

Published by: Drägerwerk AGAnaesthesia Product GroupOriginal manuscript: Josef Haupt, 19701st revision: 1996Concept and realization: Rosenbauer • Solbach, HamburgArt Direction: Fritz Meinig, HamburgPrint: Dräger Druck, Lübeck

ISBN Number 3–926762–17–9

3

The History of Anaesthesia at Dräger

Volume I

4

5

Foreword ....................................................................... 6

Early history .................................................................. 8

Entering the 20th century ...........................................14

History is made with a world „first“ .......................... 29

Inhalation anaesthesia in the Thirties ...................... 35

A fresh start ................................................................. 40

The machines of the Fifties ....................................... 53

Halothane in anaesthesia ........................................... 63

Anaesthesia machines for special use ...................... 74

Chronological survey.................................................. 94

Contents

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Foreword

Dear Reader,

It all started 150 years ago: in 1846 it first be-came possible for patients to have their teethextracted under anaesthesia. This original „etherintoxication“ was the beginning of anaesthesiatechnology, a development which has continued tothe present day – to our modern anaesthesiaworkstations.

Dräger’s name has been closely linked with ad-vances in this „medical discipline“ for over 100years. The development of Dräger anaestheticmachines showed the way forward. We are espe-cially indebted to the inventive initiative of compa-ny founder, Heinrich Dräger, and his son, and mygrandfather, Bernhard, for their pioneering,technical innovations. It was they who laid thefoundations for the world-wide reputation ouranaesthetic machines enjoy today. We know frominformation from hospitals in Germany andabroad that, true to our motto, „Technology forLife“, many Dräger machines have been in use forover 30 years. Today, the medical world continuesto associate Dräger products with ongoing techno-logical development and innovative solutions toproblems for doctor and patient alike. Drägermeans reliability and quality. We are proud ofthat legacy, to which we also commit ourselves forthe future.

Dr Christian Dräger

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This book gives a comprehensive account of thehistory of anaesthesia at Dräger. The first volumetakes us from the invention of the cylinder regula-tor at the end of the last century through to themid-Sixties, when Halothane was discovered as thenew anaesthetic agent. A second volume will coverthe years from that time up to our most recentdevelopments.

References are made to events which occurred inparallel with the Dräger developments to illustratethe historical background against which Drägerhave written their own small part of history. Thisaccount shows what engineering skills couldachieve even in the past. The exciting story hasbeen preserved in the Dräger archives, and writtenup with the benefit of his technical expertise andinvolvement by our long-serving Chief Engineer,Josef Haupt. His first publication on Drägeranaesthetic machines was published way back inthe Seventies. Today we are deeply in his debt forhis early pioneering work which provided thedetailed groundwork for this current revisededition.

And so, wishing you much enjoyment in yourreading of this history,

Yours,

Dr Christian Dräger

8

Pars pro totoThe history of many established and internationallyfamous German companies begins in the late 19thcentury. So, too, does Dräger’s history – and with itthe development of anaesthetic machines.

The oxygen cylinder was one of the importantinventions of those days which was, and still is,more closely linked to the name of Dräger thananything else. Although the physicist, Linde, haddiscovered the process of liquefaction to separateair into its components, O2 and N2, it was not untilthe 1880s that engineers succeeded in compress-ing and storing oxygen and other gases at highpressure and the first seamless, high-pressurecontainers made from hand-forged steel cameonto the market. The steel cylinder shown herecontained pure oxygen, produced by the Lindeprocess, and is probably one of the earliestcontainers of its type. The inspection mark datesthe filling to 1885.

The technology was surprisingly advanced as thecylinder can hold over 1500 litres of oxygen at afilling pressure of 150 bar. Nevertheless, materialstechnology has continued to develop to the presentday and so, as the data in the table shows, hassucceeded in increasing filling pressures andcapacity while at the same time reducing weight.Today, an O2 cylinder of equivalent size holds athird more oxygen but weighs about twenty kilosless, which means it is easier to handle.

Early history

9

Cylinder 1885 Cylinder 1970

Capacity 10.4 L 10 LExternal diameter 140 mm 140 mmLength 1235 mm 1020 mmWeight 36.4 kg 12 kgFilling pressure 150 bar 200 barO2 content 1560 litres 2000 litresWeight per litre ofstored O2 23 g/L 6 g/L

The developmentof materials technologyover 85 years.

Oxygen cylinderof 1885.

The possibility of separating gases and storingthem in compressed form was, undoubtedly, afundamental step along the road to using oxygen,but it would be only fair to say that compressed

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gas techology was still in its infancy at that time.It was the pioneering work of Heinrich Dräger(1847 to 1917) which steadily opened up the route.

Using compressed gasesIn order to use the compressed gases, early oxy-gen cylinders were fitted with the pressure-reduc-ing valves then available. However, these werecertainly not adequately developed. In fact, therewas just not enough viable equipment availablefor dispensing the oxygen stored under pressureand the users were exposed to considerable dan-ger from the pressurised containers. HeinrichDräger, the founder of Drägerwerk, became awareof this danger early on while working with pres-sure-reducing valves from various manufacturers.In the 1890s he and his son, Bernhard (1870 to1928), searched hard for new, workable solutionsto the problem.

„... At the beginning, we accepted the pressure-reducing valve uncritically as the right and properthing. We were to be bitterly disappointed. ... My sonand I started to think about the problem of thepressure-reducing valve. The result of our thinkingwas a completely new design. ...“ Heinrich Drägerwrote this in his memoirs, because his experienceof the durability and safety in use of the valves thenavailable had been so unsatisfactory.

The first device produced by this father-and-soninitiative was a valve known as the „beer pressureregulator“ which was used as a gas source tocontrol the pressure of carbon dioxide in beerbarrels. Soon after this they made a real break-

The first Nobel prize

is presented in 1901,

in memory of its

founder, Alfred Nobel.

Conrad Röntgen (for

physics) and Emil

Adolph von Behring

(for medicine) are

among the winners.

11

through by modifying the new design to make an„oxygen regulator“. The development of thisautomatic oxygen regulator, together with a newtype of cylinder valve, meant that it was possible touse a high-pressure cylinder without risk and todispense oxygen in a properly controlled fashion.A milestone had been reached, especially foranaesthesia.

The development of the injectorThe oxygen regulator with the safe, effectivecylinder valve was to stand the test of time. How-ever, Heinrich and Bernhard Dräger had anotherchallenge to overcome. Welding technology neededa way of mixing compressed gases and their successin developing an oxygen-driven injector for thispurpose was a third fundamental invention. It wasabout this time that medical technology started tonotice the achievements of the House of Dräger.

Today it is impossible to say whether the idea forthe anaesthetic apparatus came from the doctor tothe engineer or the other way round. We wouldprobably now say that the research was inter-disciplinary. What is certain, though, is that Heinrichand Bernhard Dräger were the first people inGermany to make an anaesthetic apparatus foroxygen and chloroform. To do so they worked witha close friend, Dr Otto Roth, who was the principalsurgeon at the Allgemeine Krankenhaus in Lübeck.The year was 1901.

The apparatus which was the result of this co-operation was really only a prototype but it wasthe forerunner for the Dräger apparatus which

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followed. It was very like the bubbler devicesin common use in England at the time, which arestill known today as chloroform or ether„bubblers“.

Reich patent no. 154339Clinical trials carried out by Dr Roth soon con-firmed a problem with this type of apparatus thathad already been suspected. It was difficult todeliver accurate doses of chloroform because ofcooling as a result of evaporation. Here was anotherchallenge to the ingenuity of Heinrich and Bern-hard Dräger. In record time they developed acompletely new and unique drip-feed device forliquid anaesthetic agents which used the injectorthey had developed themselves. The oxygen was nolonger routed through the anaesthetic agent butinstead passed through an injector to generatesuction. They registered their drip-feed device,and were immediately granted German Reichpatent no. 154339 on 26th August, 1902.

Naturally, it was Dr Roth who carried out theclinical trials at his hospital, and in November ofthe same year he published the news of this impor-tant development along with the results of histrials. In his article in the ‚Zentralblatt für Chirur-gie‘ no. 46, entitled „Oxygen-Chloroform Anaes-thesia“, he wrote:

„If this fault was to be eliminated, it was essential tostop passing oxygen through the chloroform. Afterlengthy trials it has become possible to drip-feed thechloroform in a way that can be seen in a specially-designed vessel using the suction effect of the oxygen

On 10 December, 1903,

the Nobel committee of

the Norwegian parlia-

ment presents the Nobel

prize for physics to Pierre

and Marie Curie.

13

flow; its special design ensures that the droplets arealways the same size, so that 50 drops always equalone gramme. An adjustable valve controls thenumber of drops and so large or small amounts ofchloroform can be fed into the oxygen flow of thedrip-feed device, as required, at the appropriaterate for evaporation. The indicator shows thenumber of drops on a scale above the valve – andalso, therefore, the amount of chloroform adminis-tered in grammes – which are evaporating within aminute. An accurate drip-feed is thus guaranteedwhich cannot be affected by the impatience of theoperator.“

Ever since this time, the name of Dräger has beeninextricably bound up with developments in anaes-thetic technology.

The drip-feed device of thefirst anaesthetic apparatus:T is the chloroform vesselwhich kept the chloroformat a constant level.B is a spring lever whichsupported vessel T. T1 isthe sightglass which moni-tored the number ofdrops. 25 drops equalledexactly 1/2g of chloro-form. R is the controlscale.28

025

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From first steps to maturityThe Handapparat 145 N or Roth-Dräger of 1902could be regarded as the prototype of a long line ofDräger anaesthetic apparatus. Its most importantcomponents were the pressure-reducer to control thegas flow from the cylinder and the drip-feed device tocontrol the flow of anaesthetic agent precisely. Westill have both these components after many decadesbecause they were produced as a journeyman’s pieceby a fine mechanic in the Dräger factory at that time.These two components were used in the reconstruc-tion shown here.

Operating principleOxygen stored at 150 bar in the steel cylinderwas reduced in pressure and dispensed by the

Entering the 20th century

The prototype in a series ofDräger anaesthetic apparatus,1902:Hand-held apparatus 145 N.

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pressure reducer. The gas simultaneously drovean injector which drew chloroform from a stor-age bottle. The anaesthetic agent could be accu-rately controlled by the number of drops perminute, and evaporated in the oxygen flow. Thepatient then inhaled the resulting anaestheticmixture, which has been pre-set by the anaes-thetist, from a breathing bag via an inspiratoryvalve, hose and mask. Expiration to the atmos-phere took place via a separate expiratory valveon the mask. It was, as we would call it today, asemi-open system (non-rebreathing system),accurately controlled by thin, mica plate valveswith low resistance.

This first design was developed a stage furthersoon after it appeared. On the suggestion of ProfGeorg Krönig from Jena, and with his co-opera-tion, a second drip-feed device was added. Thiswas designed for a second anaesthetic agent, thatis for ether. In 1903 Dräger, therefore, had threemodels available, all similar in design but withdifferent options for administering anaestheticagents:

� oxygen/chloroform� oxygen/ether� oxygen/chloroform/ether

A year later Dräger exhibited an anaestheticapparatus at the World Exhibition in St Louis,USA. This apparatus aroused great interest andwas regarded as a pioneering „first“. Drägerreceived a silver medal for its Oxygen-Chloro-form Apparatus.

Years of trials lead to a

first great success for the

Wright brothers in 1903:

Orville Wright’s motor-

ized aeroplane is able to

stay in the air for 12

seconds, and fly a dis-

tance of 70 metres.

16

This diploma was presentedto Heinrich Dräger at theSt Louis Exhibition in the USAin 1904, together with a silvermedal for the outstanding„Dräger Oxygen-ChloroformApparatus“.

From prototype to batch productionSuccess and world-wide recognition assured Hein-rich and Bernhard Dräger that they were on theright path, and led to more new designs and modi-fications. They had two objectives: on the onehand, they aimed for cost-effective batch produc-tion; on the other, experience in daily clinical usehad shown that the drip-feed device could still beimproved.

The outcome of their work, the Roth-DrägerMixed Anaesthetic Apparatus was launched in1910. The way in which it worked remained basi-cally the same as that of its predecessors, but thetwo objectives set had been reached.

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Number Two:The 240 N double apparatus,1903.

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In 1910, the Roth-DrägerMixed Anaesthetic Apparatuswas developed in co-opera-tion with surgeon friend,Dr Otto Roth.

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A contemporary illustration shows how the appara-tus worked: „The illustration is a cross-section draw-ing of the two drip-feed components. When valve H isopened, the low pressure set with adjusting screw B onreducing valve A according to pressure gauge M flowsto injectors D1 and D2. A vacuum is produced insightglasses K1 and K2, and the anaesthetic agent issucked up the risers S1 and S2 and drips visibly andaudibly from drip-feed cones V1 and V2 into theoxygen flow from the injectors. The number of dropsper minute is controlled by changing the vacuum inthe sightglasses with valves R1 and R2. Opening thevalves wider increases the flow of the circulating gasand so the vacuum is lowered and vice versa. Chloro-form-oxygen vapour and the ether-oxygen vapour aremixed in a breathing bag or reservoir bag G and arerouted through the inspiratory non-return valve P intothe metal hose leading to the mask.

Technical drawing of theRoth-Dräger Mixed Anaes-thetic Apparatus for etherand chloroform.

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The illustration „... shows how the injector in theapparatus, which has been described, is actuallymade. The pressure jet (a) and the venturi (b) canbe removed with a screwdriver so that cleaningis easy ...“

All of this apparatus was a great success forDrägerwerk. By 1912, that is in the first ten yearsof Dräger anaesthetic technology, over 1500 ma-chines had been sold throughout the world.

Greater safety in anaesthesiaMedical developments and the demands of anaes-thetists and surgeons very soon led to furtherchanges to the original Dräger anaesthetic appara-tus which Heinrich and Bernhard had made in1902 in co-operation with their friend, Dr OttoRoth. Just a few years later an Anaesthetic Artifi-cial Respiration Apparatus was produced. This wasintended for artificial pneumatic ventilation andwas named the Roth-Dräger-Krönig after thecollaborators. This apparatus had a second oxy-gen-driven injector which was independent of theanaesthetic components. With this injector and ahand-operated switching valve, positive and nega-tive pressure could be produced in a tight-fittingventilation mask. The anaesthetist could nowdiscontinue anaesthesia, if breathing stopped orsome other incident occurred, and reflate ordeflate the lung with oxygen-enriched air inbreathing rhythm.

An important development:the Dräger injector, anaccurately controlled drip-feed device.

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Dating from 1911:the Roth-Dräger-KrönigPositive Pressure MixedAnaesthetic Apparatus, withProf Bruhns’ positivepressure device.

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Open thorax surgeryAttempts by surgeons to carry out open thoraxoperations were the trigger for Drägerwerk tofurther develop the Roth-Dräger. Attempts torespond to the demands of surgery first began in1905. The problem that open thorax operationspose to the engineer is that when the thorax isopen the lung has to be kept inflated with positivepressure during inspiration and expiration toprevent its collapse. The chamber which wasinvented and used by Prof Sauerbruch was notsatisfactory because it was too expensive andawkward to use. Drägerwerk’s designers madeseveral attempts to solve the problem. One exam-ple was the Brauer-Dräger Positive Pressure

Still expensive and difficultto handle, the Brauer-Dräger Positive Pressuremachine for use duringsurgery on the open thorax,1906.

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Machine. A contemporary sketch gives someinsight into its design.

A whole series of different designs of apparatuswere tested clinically until finally, in 1911, theRoth-Dräger-Krönig Positive Pressure MixedAnaesthetic Apparatus was ready for marketing.Again it was the injector, a component whichwas now standard for Dräger, which solved thepositive pressure problem. This was driven byoxygen, independently of the anaesthetic com-ponent, via a separate shut-off valve and pres-sure reducer. The injector entrained a relative-ly large, but regulated, volume of fresh air,which was delivered to the lung via its ownhose and a tight-fitting mask. The degree ofpositive pressure could be controlled with aspring-loaded expiratory valve on the mask.When using this first, practical solution to theproblem, the flow of anaesthetic gas had to bestopped during the positive pressure phase.This was certainly a handicap, as was obviousto Dräger, and a problem that their ingenuitycould not leave unsolved. Further work was tobring success.

In 1912, Drägerwerk was able to present acombined apparatus for mixed anaesthesia,positive pressure anaesthesia and artificialrespiration. This apparatus was seen as asignificant improvement and a useful combi-nation of the three preceeding Roth-Drägermodels. It became world famous as the Dräger-Kombi and maintained its high reputation forover 30 years.

On the tenth day before

Christmas, the Norwe-

gian, Roald Amundsen,

and his team of four

explorers are the first to

reach the South Pole. His

competitor, Robert Scott,

loses the „race“ to the Pole

and arrives there second

on 12th January, 1912.

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Dräger’s combined anaes-thetic apparatus of 1912,known by doctors as the„Dräger-Kombi“, enjoyedworld-wide success for over30 years.

A contemporary summary written by its designer,Hans Schröder, explained how it worked extremelywell.

The illustration „... shows the Roth-Dräger com-bined apparatus for routine anaesthesia, for posi-tive pressure anaesthesia and for artificial respira-tion. It also includes an injector which sucks infresh air when the large selector valve is set atpositive pressure. Anaesthetic gas is routed to the

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The selector or switchingvalve on the same apparatus.

selector valve from the well-known drip-feed appa-ratus, and the anaesthetic mixture flows at positivepressure through the hose to the mask. A secondhose routes the expiratory gases through the posi-tive-pressure control valve to the atmosphere. Thepressure gauge displays the positive pressure in cmof water. The light-weight aluminium hoses are25 mm in diameter. A head band with straps en-sures that the mask is airtight. It should be notedthat the head band has two side arms whichprevent the straps from exerting any pressure onthe carotid arteries.

If artificial respiration becomes necessary for anyreason the drip-feed apparatus has, of course, to

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be switched off and the selector valve set to „Pul-motor artificial respiration“. The indicator on theselector valve is then moved from the inspirationstop to the expiration stop and back again in therhythm of natural breathing, i.e. 15 to 16 timesper minute. The suction and the pressure effectsof the injector then operate alternately. Duringinspiration, the lung is inflated with oxygen-enriched fresh air at an end pressure of about20 cm of water, and during expiration the lung isdeflated by the same force. That is to say, themachine performs a task which cannot be donemanually.

For routine anaesthesia a narrower metal hose isused with a standard mask and the selector valve

The Dräger-Combi’s air-tightanaesthetic mask with headband and neck straps. 67

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Dräger’s well thought-outrange of batch-producedanaesthetic apparatus whichwas available all over theworld in 1913.

is set to „mixed anaesthesia“. The gases are routedthrough different holes in the selector valve, de-pending on the indicator setting, as the situationrequires. It is not appropriate to describe the designin more detail at this point, except to mention thatthese selector valves, which allow the method ofoperation to be changed in one movement, are verypopular with those who practise anaesthesia.“

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First radio news broad-

cast on 20th August 1920,

transmitted by station

8 MK in Detroit.

Dependability and acceptance throughoutthe worldBefore the First World War, Drägerwerk offered acomprehensive and well thought-out range withits four models of anaesthetic apparatus, shown inthe photograph of the Dräger stand at the SurgeryCongress at the Berlin Charité in 1913 (see page 27).These four models marked the end of the firstphase in the development of Dräger’s anaesthesiatechnology. They were sophisticated by the techni-cal standards of the time, and many gave goodservice in operating theatres all over the worldright into the 1940s. „Without doubt this was dueto their unusual reliability and consistency in use,“said Prof Jürgen Waversik, in 1980.

The Dräger-Kombi Universal Anaesthetic Appa-ratus sold throughout the world. A few years ago,the Dräger agent in Japan mentioned a DrägerCombi delivered in 1912, which was still inKyushu Imperial University Hospital as a valuedmuseum piece.

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History is madewith a world „first“

From chloroform to nitrous oxideFrom the beginning of the Twenties, and especial-ly in Britain and America, doctors began to makeincreased use of a new anaesthetic agent, laugh-ing gas (nitrous oxide or N2O). Nitrous oxide wasmuch more effective than chloroform, which hadbeen used until then, but it was a relativelyexpensive anaesthetic agent because of the man-ufacturing process. Once nitrous oxide becameknown in Germany, doctors and medical engi-neers began to search for the best method ofusing it, and, especially, how to minimise gasconsumption.

The expertise which Drägerwerk had gained inthe early years of the century could now be usedafresh. As early as 1903 Dräger had developed adevice which operated as a „closed breathingcircuit“ and which allowed rebreathing to takeplace. In the intervening years, Dräger breathingprotection equipment had become known all overthe world. American miners, who particularlyused these masks, were even nicknamed‚draegermen‘. The masks were important inarduous underground working conditions be-cause exhaled oxygen could be re-used – by therebreathing principle – and so vital gas couldbe saved.

Drägerwerk’s early attempts to use a „closedbreathing circuit“, as it was then known (now wetalk of a circle system), for anaesthetic machines,were doomed to failure. This was not because theidea was wrong but because the chloroform thenused as the anaesthetic agent reacted with the soda

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lime when a CO2 absorber was inserted in thecircle system, so that it was impossible to use thismethod for anaesthetic purposes. Nevertheless,this circle system had gained some acceptance asearly as 1906 and had been described in anarticle by Professor Franz Kuhn in the journal‚Deutsche Zeitschrift für Chirurgie‘.

The first circle system in the worldAlmost 20 years later, in 1924, engineers atDrägerwerk recalled previous knowledge andrediscovered the circle system for a „modern“anaesthetic agent, narcylene. In the Twenties thishighly purified acetylene had a definite role as afirst-class, fast and gentle anaesthetic gas. In1925, the Dräger Narcylene Anaesthetic Machine,came into being through co-operation withdoctors at the University Clinic of Würzburg. Itwas based on concepts developed by Gauss andWieland.

In developing the narcylene anaesthetic machineDrägerwerk engineers responded to the needs ofthe time. The machine already worked likeModel A and had the same circle system. How-ever, narcylene was soon abandoned, although itwas an outstanding anaesthetic agent in someways, since it was highly flammable and alsoexplosive. For these reasons, it could only have alimited role in medicine and could not be widelyused for anaesthesia. It was only when nitrousoxide became available two years later that amajor breakthrough was made. Working with DrPaul Sudeck and Dr Helmut Schmidt of theUniversity Clinic of Hamburg-Eppendorf, a

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Model „A“, the first circlesystem anaesthetic machinein the world, 1926.

completely new machine (Model A) was developedfor oxygen, nitrous oxide and ether which wasbased on the rebreathing principle. The ether wasused mainly to deepen the relatively shallowanaesthesia of nitrous oxide.

The new circle system soon became an integralpart of anaesthesia technology. All previous nitrousoxide machines, particularly outside Germany, stilloperated on the semi-open system. Rebreathing

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systems with carbon dioxide absorbers for use inanaesthesia were also being developed in English-speaking countries. In 1924 Ralph M. Watersintroduced a „to-and-fro“ system and in 1930 BrianC. Sword and R.V. Foregger designed a circlesystem.

A comparison of the two systems shows how theyworked (page 51, first and third drawings).

Model ADräger made the first batch-produced anaestheticmachine with a circle system in the world,Model A, to take advantage of the benefits ofnitrous oxide and the outstanding features of thenew circle system. A contemporary operatingdiagram shows why this circle system should beregarded as the pioneer for all later developments.It has all the features which have remained thefundamentals of anaesthetic machines right up tothe present day. These were:

� Separate hoses for inspiration and expiration. � Large area, springless, thin mica plate valves of

low resistance. � The carbon dioxide absorber, which could be

switched off partially or completely, was a dispos-able cartridge even at this stage.

� Breathing bag to give the option of manual venti-lation.

� Vent valves or pressure-limiting valves wereavailable on request.

In 1924, the ten-millionth

Ford, the „tin lizzy“ rolls

off the assembly line:

at the time it cost just

under 300 dollars.

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A simplified illustrationof the design of Model „A“.The old dynamic pressure principle was a proven

way of regulating the flow of nitrous oxide andoxygen. This method allowed the anaesthetist toset the desired or required volume of nitrous oxideaccurately in litres per minute in relation to thepercentage of oxygen. Ether was added, as in thewell-known Roth-Dräger mixed anaesthetic appa-ratus of 1910, by the proven vacuum drip-feedprocess.

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Futuristic appearance of theDräger Narcylene Anaestheticmachine designed accordingto Gauss and Wieland’s con-cepts, 1925.

It says a great deal for its high technical stand-ards and its longevity that a specimen of Model Awas still in daily use in the University Clinic inRostock in 1947, that is 22 years after it wasinstalled.

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Superheated ether anaesthesiaAn accepted worldwide standard for the technolo-gy of anaesthetic machines was set by the devel-opment of Model A and no revision was called forthroughout the Thirties. Nevertheless, it was –and still is – Drägerwerk’s claim that new chal-lenges are always met. Hence, besides carryingout trials of narcylene as an anaesthetic agent,Dräger was involved in developing another new-comer to its range of anaesthetic machines. Thismachine was the brainchild of Dr Max Tiegel,surgeon at St Petrus Hospital in Trier. Instead ofadministering ether in liquid form via the injector– as in the Roth-Dräger Combined AnaestheticApparatus – he wished to use ether as a vaporisedgas. The end result, the Dr Tiegel-Dräger Anaes-thetic Apparatus for superheated ether vapour,was launched in 1934.

In that year, the development engineer describedthis new apparatus as follows: „Dr Tiegel of Trierhas carried out extensive clinical trials with ethervapour, produced at high temperatures and imme-diately mixed with air so that the extremely finemolecular distribution of the nascent state ispreserved. He has established that the best anaes-thetic effects are achieved when the ether drops arevaporized at 60°C. In this situation, side effects areminimised – in particular no post-anaestheticvomiting.“ Dr Tiegel’s apparatus worked bydripping ether onto an electrically-heated silverplate in controlled amounts. A thermostat keptthe silver plate at a constant 60°C. The resultantether vapour combined with the ambient airbreathed in by the patient, just as it does in a

Inhalation anaesthesiain the Thirties

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The Dr Tiegel-DrägerAnaesthetic machine of1934 for superheatedether vapour.

draw-over system. Expiration was through aseparate second hose. The inspiration and expira-tion rhythms of the patient were separated in asimple way with a water non-return valve. Anoth-

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er detail of the design was truly pioneering: forthe first time an activated carbon filter wasinstalled in the expiration hose to absorb anyremaining ether contained in the expiratory air.This was a significant step in reducing the healthrisks for surgeons, anaesthetists and assistantstaff. Even in the Thirties, Dräger had thoughtand acted with concern for the environment inthe field of anaesthesia.

In spite of its distinct advantages, the Dr Tiegel-Dräger anaesthetic apparatus for superheatedether vapour remained an outsider in anaesthesiaand never made any real breakthrough.

Optimisation of the proven standardTwenty-four years after it was first made, the Roth-Dräger-Krönig Mixed Anaesthetic Apparatus(page 21) was updated in 1935. Basically it wasimproved by adding a new positive pressurefeature, injector-driven as might have been ex-pected. It had a spring-loaded breathing bag andwas designed in such a way that the anaestheticgas could be delivered at positive pressure, ifrequired. This meant that, during open thoraxsurgery, the anaesthetist no longer had to switchoff the anaesthetic gas flow. Another advantage ofthe new type MÜ positive pressure mixed anaes-thetic apparatus was that, with this new design,the pressure fluctuations between inspiratory andexpiratory phases were much smaller than before.

Technical development at a standstillWith the growth in totalitarian fascism in Germanyand the outbreak of the Second World War in 1939,

The first comic was sold

from news-stands in USA

in May 1934 – the begin-

ning of an era.

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The „MÜ type“ positivepressure mixed anaestheticapparatus, from the houseof Dräger, 1935. 10

044

39

Drägerwerk was not able to continue its develop-ment of inhalation anaesthesia. From a technicaldevelopment point of view, this period has to beregarded as a long enforced break in which medi-cal engineering had to be subordinated to theinterests of national socialism.

The updated Roth-Dräger anaesthetic apparatusremained standard equipment until the end of theSecond World War. Progressive hospitals usednitrous oxide in Model A, though some non-con-formists preferred the Tiegel.

The inventor and engineer,

Carl von Linde, dies in

Munich at the age of 92.

He had discovered a

process for the manufac-

ture of liquid air in 1895,

and of liquid oxygen in

1902.

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Return to the world classAfter the end of the Second World War, researchand development in inhalation anaesthesia startedafresh in Germany. In contrast with earlier years,nitrous oxide was now available in much greaterquantities and it was also, therefore, cheaper.Since Hoechst had introduced an improved pro-cess for manufacturing nitrous oxide for aero-engines during the War, supplies were adequatein what was otherwise a difficult period of recon-

A fresh start

One year after the end of thewar: Model „D“ in use in theoperating theatre of the Mu-nicipal Hospital Ost in Lübeck,under the guiding hand ofProfessor Lezius.

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struction. Nitrous oxide had become the stand-ard anaesthetic gas for British and Americananaesthetists and it was clear that significanttechnical advances in anaesthetic machines hadalso taken place in these countries in parallelwith this development. Catching up had to beDrägerwerk’s top priority.

The Model D oxygen/nitrous oxide anaestheticmachine was developed in 1946, only one yearafter the end of the War. As was appropriatefor a time of shortages, model D was intendedto be a simple machine with a partial rebreath-ing system. What was new, though, was thatmost of the functional instruments werehoused in a console with a control panel, theforerunner of the enclosed instrument systemwith a cabinet.

It was soon apparent that this simple design ofoxygen/nitrous oxide anaesthetic machine wasexactly what was needed. It came on stream atjust the right time to meet the pent-up demandfor general surgery in Germany which hadbeen caused by the War.

Circle system anaesthesiaBy the late Forties, surgeons were beginning tofind Model D inadequate as this type of ma-chine had only limited use in thorax surgery, afield which was growing in importance. Build-ing on their proven Model A, Drägerwerkdeveloped a circle system anaesthetic machinein 1948, Model F, which used oxygen, nitrousoxide and ether.

In 1946, Japan grants

women the vote for the

first time in its history.

42

The Dräger Model F circleanaesthetic machine, 1948.

15 4

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Model F was the first Dräger machine in which thegas flow was controlled directly by flowmeters, theso-called rotameters, and not indirectly by staticpressure measurement. Model F also boastedseveral other ingenious improvements, such as theoption of connecting cyclopropane and carbondioxide as additional gases. The circle system, stillknown at that time as a re-circulating system,could be stripped down completely for cleaningpurposes and for steam sterilization, without usingany tools.

The CO2 absorber had been designed by theDräger engineers to be refillable. When the soda

Operating diagram for ModelF with circle system – a worldfirst – with bronchial suctionindependent of motor or elec-tric power.

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44

Einstein develops a mathe-

matical explanation for

how the planets and the

universe function. Scien-

tists greet his theory of

gravity with universal

astonishment at the end

of December 1949.

lime needed to be replaced, the container could bechanged in seconds – even while anaesthesia wasin progress. To save soda lime, there were twoabsorbers and it was possible to switch from one tothe other. The anaesthetist could also remove theabsorber from the system – again in seconds –during anaesthesia so that expiratory carbondioxide could be used to stimulate breathing.

Model F was also the first anaesthetic machine inthe world to provide bronchial suction which didnot depend on a motor or electrical power. Asmight have been expected with Dräger, thisworked in the same way as the old, oxygen-driveninjector, but the principle was now used for anejector, which achieved suction of up to -6 metreswater gauge in the suction catheter. Subsequently,the negative pressure was further improved, up to-9 metres water gauge. As a result, Model F pro-duced a suction unrivalled by any of the traditionalmotor-driven OP suction devices of the time.

Model F was, as was appropriate for the time,completely tailored to the needs of the Germanmarket. In other countries, particularly marketssupplied by the USA, anaesthetic machines withmore gases were in demand. To make the ma-chines easier to handle, these gases were stored insmall cylinders.

Response to the international marketIn order to catch up with the competition in for-eign markets as much as anything, Dräger re-sponded to the trend for more gases and smaller,lighter cylinders. Model G was designed as the

45

„Modern Times“ DrägerModel G Circle SystemAnaesthetic machine, 1950.

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Drägerwerk answer to international demand.

This compact machine came on stream in 1950and had the option of connecting from two to fivegases: two cylinders each of oxygen and nitrousoxide were standard, with cyclopropane, heliumand carbon dioxide as additional options. The oneand two-litre steel cylinders used were fixed tothe machine with yoke connectors which con-formed to American Standards. Connectors of thistype were not approved in Germany because theylooked alike and there was, therefore, a risk thatmistakes would occur. In fact, mistakes didhappen quite frequently until a „pin-index“system was developed to prevent them in the lateFifties.

The variety of gases available meant that morepipework was required and that non-returnvalves had to be included. All the measuring andoperating instruments were built into a stream-lined, desk-style housing, and a clock was in-stalled on the rotameter block to assist the anaes-thetist with time checks. The circle system fromthe earlier Model F was also incorporated. Al-though the machine was received with somescepticism abroad to begin with, because of itsunusual design, its sturdiness and practicalitysoon won the critics over. In fact, Drägerwerkstayed with this basic concept right into theEighties.

Introducing more convenience into the rangeThe factors which had led to the introduction ofan instrument panel in Model D and a machine

While black and white

television is still being

developed in Germany,

the first TV programmes

in colour are transmit-

ted in the U.S.A. from

1951.

47

housing in Model G began to gain steadily inimportance for everyday use. Dräger was alreadywell-known for the efficiency, reliability andlongevity of its anaesthetic equipment but it wasnow becoming essential to consider ergonomicsand ease-of-use as well, when designing anaes-thetic equipment. The demand for more conven-ience in anaesthetic equipment led to the intro-duction of Romulus, a re-circulating anaestheticmachine, in 1952.

It was no different from its predecessor, Model G,in the way it worked but it was different in how itwas organised. A cabinet was built in below themachine housing which incorporated severaldrawers, a writing surface and an instrument trayfor the anaesthetist. Gas was supplied from a two-and a ten-litre oxygen cylinder and a two-litrenitrous oxide cylinder. Small cylinders of C3H6 andCO2 could also be connected. The clock on theflowmeter block, designed by Dr Weyland, withspecial scales and a stop hand for measuring pulseand breathing frequency, became the DrägerAnaesthetic Clock.

The blood pressure gauge was next to the rotame-ter block, which was to become its usual place,and a filled replacement absorber was on the left,ready for use. In short, on the outside, Romuluswas a practical and highly efficient newcomer onthe anaesthesia market.

Romulus had also been modified on the inside.The circle system (Circle System I) had a numberof improvements:

48

The Dräger Romulus circlesystem anaesthetic machine of1952 was designed primarily forthe home market. Its twin,Remus, identical in constructionbut designed for smaller gascylinders, was developed forexport.

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� The range of the pressure relief valve had beenextended to +30 cm water gauge and its adjust-ment had been improved.

� The inspiratory and expiratory valves had beendesigned to work without springs, and so hadlower breathing resistance.

� The ether drip-feed device had been replaced witha vaporizer which gave more accurate control ofdosage.

� To facilitate manual ventilation, a bellows with asimple volume limiter could be connected insteadof the breathing bag.

The Remus anaesthetic machine, a twin brother tothe Romulus, was designed by Drägerwerk specifi-cally for the export market which they were slowlyopening up. The only way in which it differed from

Operating diagram forCircle System I.

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its twin was in the size of the cylinders thatwent with it, as it was fitted with smaller gascylinders (two of oxygen and two of nitrousoxide, C3H6 or He).

At the beginning of the Fifties, the era of theeconomic miracle in Germany, German anaes-thesia slowly became „emancipated“, so thatDräger began to receive requests for customizedmachines for particular purposes from custom-ers in Germany and abroad. New variations inthe design and equipment of anaesthetic ma-chines were always being found whenever thiswas technically and economically feasible.Soon, Romulus and Remus, the two cabinetmachines which were hardly cheap, werefollowed by the Agrippa 1, 2 and 3 range ofmachines. In principle these were a simplified,and, therefore, cheaper successor to Model Fafter 1948. The Agrippa models differed fromeach other merely in the number of gasesavailable:

� Agrippa 1 (formerly Model M) for oxygen/ether� Agrippa 2 (formerly Model N) for oxygen/

nitrous oxide/ether� Agrippa 3 for oxygen/nitrous oxide/cyclopro-

pane/ether

On 6th February, 1952,

Elizabeth II is proclaimed

queen and accedes to the

throne in Britain at the

age of 23.

51

Operating diagram forCircle System Ia.

inspiratoryphase

expiratoryphase

„closed“ system

„semi-closed“ system

„semi-open“ system

„open“ system

20 8

3920

840

20 8

4120

842

52

The 1952 Dräger Agripparange, successor to Model F.

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The PulmomatThe Dräger Pulmomat appeared in 1952. This was anew type of ventilator which operated automatical-ly and was driven by compressed oxygen. It wasdesigned as an additional unit to be connected toany Dräger anaesthetic machine with a circlesystem. Its function was described in detail in acontemporary brochure:

„Automatic method with the PulmomatUsing the Pulmomat, patients can be ventilatedconsistently and completely automatically, evenduring lengthy surgery, so significantly easing theburden on the doctor who would have had toventilate the patient by manual methods otherwise.An accurately adjustable volume of gas (between100 and 700 cc) is forced into the patient’s lung(inspiration) and then sucked out at low negativepressure (expiration). The support given to expira-tion by the negative pressure is of particular impor-tance in open thorax surgery, as the elastic forceswhich cause spontaneous breathing are then re-duced. The blood circulation is also assisted by thefilling of the right ventricle during the negativepressure phase. Suction of up to -10 cm watergauge helps to overcome the expiratory resistance –particularly in endotracheal anaesthesia – leavingless residual air in the lung. The pressure gauge onthe Pulmomat allows control of ventilation pres-sures in the lung and the mean airway pressure.Pressure values can be controlled accurately whenthe patient is being ventilated with the Pulmomatbreathing bag (during the transition phase beforethe onset of breathing failure or when spontaneousbreathing is being re-established).“

The machines of the Fifties

54

This machine, which operated on the old Pulmotorprinciple, was very rapidly accepted by anaesthet-ists. It provided a great deal of assistance especial-ly during lengthy anaesthesia when muscle relax-ants had been used. The Pulmomat soon becamestandard equipment with Dräger anaestheticmachines and, with minor improvements such asan increase in tidal volume to 1000 ml, it wasmade and sold right into the Seventies.

Breathing systems on demandDräger offered its Oscillation System as an item ofsupplementary equipment, especially to overseassupporters of the „to and fro“ system. This had

Operating drawing of 1952 forthe Dräger Pulmomat.

1 = plastic hood2 = changeover valve3 = bellows4 = breathing bag5 = corrugated hose6 = pressure gauge7 = reversing device

8 = adjusting device forstroke volume

9 = frequency control valve10 = base plate11 = fixing screws for

plastic hood12 = pressure reducer

13 = pressure hose14 = shut-off valve

for driving gas15 = knurled screw16 = knurled nut

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Expiration

Inspiration

55

different sizes of absorber for adults and children,and there was even one for infants and neonates.It could be used with any Dräger anaestheticmachine from Model F onwards.

Various items of supplementary equipment wereavailable for the „semi-open system“ – and werealso suitable for all Dräger apparatus, of which thefollowing three are examples:

� The Magill System which did not have valves,which was British practice at the time, though itdid have optional, coarsely variable, partialrebreathing.

� The Dräger Semi-Open System which was accura-tely controlled by inspiratory and expiratory valvesand so did not have rebreathing, but did have amanual ventilation option.

� A Valveless Kuhn System which was especiallydesigned for children and neonates, and did have amanual ventilation option.

A new circle systemThe Fabius range, which was developed in themid-Fifties, was originally designed for the mili-tary medical corps as a portable anaestheticmachine (see also page 74 – Anaesthesia ma-chines for special use). Fabius was offered to theanaesthetist working with casualties as a portableanaesthetic machine. From 1956 onwards, thehospital version of Fabius also offered a choice ofdifferent gas cylinders.

What was really different about Fabius, as opposedto other Dräger machines, was the circle system.

56

This Circle System II had an absorber which couldbe switched off during anaesthesia, either com-pletely or partially, by a conical rotary valve.Adjustable (partial) rebreathing was thereforepossible. The circle system was also designed to bechanged over very easily so that it could operate asa semi-closed system, or a semi-open system withfresh gas, or on the „draw-over“ principle withambient air.

The Spiromat anaesthetic machineSince there were distinct advantages for thesurgeon, as well as for the patient, in relaxingthe breathing muscles during anaesthesia forthorax surgery, anaesthetists became increasinglyinvolved in assisting and controlling venti-lation.

Circle System II andits operation in differentmodes.

„closed“ system „to and fro“ system

„open“ system with freshgas from cylinders

„open“ system withambient air

Frischgas

Luft

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The Dräger Fabius anaes-thetic machine, originallydesigned as a portablemachine, 1956.

Much experience was gained during the interna-tional polio epidemic at the end of the Fortiesand in the early Fifties. During this time, a largenumber of ventilators were developed in Ameri-ca and in Europe – and of course at Dräger –which operated more or less automatically.

Dräger transferred this expertise into anaesthesiatechnology and into the development of the Spiro-mat 5000 anaesthetic machine which waslaunched in 1959: it was designed as a combina-tion of the Spiromat 4900 long-term ventilator andthe Romulus anaesthetic machine. This electrical-ly-driven machine had to be made intrinsically

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The Dräger AnaestheticSpiromat machine in clinicaluse in 1959.

safe and explosion-proof as it was going to be usedin the operating theatre. With the Spiromat 5000anaesthetic machine, an experienced anaesthetistcould match ventilation parameters closely to theinvividual needs of the patient and the operation.

� Accurate selection and adjustment of tidal volumebetween 50 and 1000 ml.

� Ventilation frequency adjustable from 10 to 40 perminute.

� Pressure reserve (+45 mbar) to ensure constanttidal volume, even when breathing resistanceincreased.

� Adjustable mean airway pressure for ventilation. � Inspiratory:expiratory time ratio could be selected

and set between 1:1 and 1:2.

20 1

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An extract and two illustrations from a contem-porary brochure show how the machine worked:

„An electrically-powered blower (1) inside themachine produces compressed air which is routedvia a mechanically-controlled switching valve (2)to a plastic hood (14) where it operates the bel-lows (13).

In the closed or semi-closed system, the bellows (13)is filled with anaesthetic gas. When the bellows iscompressed by the pressure the anaesthetic gascontained in it passes through the inspiratory valve(22) and the inspiratory hose to the patient. At theend of inspiration, the switching valve (2) stops theflow of compressed air and connects the suction sideof the blower to the air space under the plastichood, thus producing negative pressure under thehood. This negative pressure expands the bellows sothat expiration takes place.

The gas expired by the patient flows through theexpiratory hose, the expiratory valve (21) and thevolumeter (24) and, after mixing with the fresh gasflowing through hose (35) arrives back in thebellows via the absorber (30) and the valve block(29). The expired CO2 is bound in the absorber andat the end of expiration the excess anaesthetic gasescapes through the valve (12).

In the semi-open system, the bellows (13) is filledwith either fresh air or anaesthetic gas. The bellowsis compressed by the pressure under the plastichood, and the gas inside is delivered to the patientthrough the inspiratory valve (22) and the inspira-

The race to the moon has

started. In September

1959 the Soviets land a

rocket on the moon

successfully and plant the

Soviet flag.

60

Operating diagram ofAnaesthetic Spiromat 5000 inthe inspiratory phase.

Inspiration

26

21 22

11

10

12

41

23

29

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43

2831

31

33

32

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64 70

20

3

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98717

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22 0

18

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Operating diagram ofAnaesthetic Spiromat 5000in the expiratory phase.

Expiration

26

21 22

11

10

12

41

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2831

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In December 1959,

12 nation states sign a

treaty in Washington

declaring the Antarctic

a neutral zone for

friendly research

projects.

tory hose. At the end of inspiration, the switchingvalve (2) stops the flow of compressed air andconnects the suction side of the blower via the airspace under the plastic hood to the expiratory hoseand to the expiratory valve (21) to cause expira-tion. The expired air escapes via the blower to theoutside, while the bellows is simultaneously beingexpanded by the negative pressure building upunder the plastic hood and filling with air throughthe valve (36) or with anaesthetic gas from the bag(37), via a fine dust filter and bacterial filter (18).

The ratio between inspiratory time and expiratorytime and the frequency of the switching valve (2)is determined by a stepless mechanical drive and itcan be altered with rotary knobs (5 and 6).The working pressure is set with two rotary knobs(3 and 4). The positive pressure in the system isautomatically limited by a safety valve (17) to 45cm H2O, and cannot exceed this even at extremelyhigh gas flows. The tidal volume is determined bythe stroke of the bellows. It is measured duringexpiration with the Volumeter (24) and can bechanged with the setting device (10).

The Spiromat anaesthetic machine is particularlysuitable for ventilating infants, as it can help toovercome the increased breathing resistance causedby narrow catheters.“

63

The principle and the Dräger VaporBetween 1958 and 1960 anaesthesia was present-ed with a new anaesthetic agent, halothane, ahalogenated hydrocarbon. Halothane possessedsome completely new and highly welcome prop-erties so that ether soon became virtually redun-dant.

The most important advantage of halothane isthat it is not flammable at the concentrations of

Halothane in anaesthesia

Operating drawingfor Vapor.

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Operating procedure forVapor:1 read temperature2 align concentration curve

with temperature value3 accurate flow control and

a constant concentration.

oxygen and nitrous oxide which are used in anaes-thesia in total contrast with explosive ether. Howev-er, because it has a very narrow concentrationrange for clinical applications it has to be adminis-tered in accurate doses, again in complete contrastto „harmless“ ether. This problem had to be solved,but traditional humidifiers and vaporizers could notprovide an answer. Dräger therefore designedVapor, a halothane vaporizer which controlled theconcentration with an accuracy which had neverbefore been achieved.

Vapor was designed to be connected to any Drägeranaesthetic machine produced since 1948 and, from1960 onwards, it became an integral component inthe new „Roman emperor“ generation of machines(Sulla, Titus etc.).

The following extract from the original brochuredescribed Vapor as follows:„The Vapor is connected to the basic machine in sucha way that all the fresh gas flows through it and isenriched with halothane. The Vapor delivers theconcentration set in vol.% with great accuracy, evenduring lengthy anaesthesia and the pressure changeswhich occur in artificial ventilation.Because it has a wide flow range from 0.3 to 12 L/min

3

1

1,520

12

2

2824

161 2,5

2

41 0

30

65

of anaesthetic gas, it may be used to give accuratedoses in closed or semi-closed systems when the fresh-gas flow is very low and there are, therefore, onlysmall amounts of halothane. The concentrations canbe continuously adjusted from 0.3 to 5 vol.%.

The heat required for vaporization is supplied by acopper block which covers the vaporizing chamber.(Experience in the early years had shown that itsweight could be reduced from 25.4 kg to 13.8 kg).Copper has great heat capacity and also very highthermal conductivity. The copper block is largeenough to provide sufficient heat for routine evapora-tion in practical use. A mercury thermometer has beenincorporated in the Vapor so that the values it showsmay be used when setting the % scale.

A built-in pressure compensator ensures that theconcentration supplied by Vapor remains constanteven during artificial ventilation when positive andnegative pressure occurs. If there is no compensationfor alternating pressure, the halothane vapour in thevaporizing chamber would be compressed during thepositive pressure phase and expanded during thenegative pressure phase, so that the concentrationcould rise to twice the value set.“

The „Roman emperors“One could say that, in 1960, the Octavian anaestheticmachine was designed around Vapor. It was, in allsenses of the word, a weighty competitor for Romu-lus. Octavian had a built-in Vapor for halothane,with the halothane being mixed into the fresh-gasflow for safety reasons. Circle System III also cameinto being with Octavian.

On the 9th November,

1960, John F. Kennedy is

elected President of the

United States by the

narrowest of margins –

0.1 percent of votes.

66

The Dräger Octaviananaesthetic machine duringsurgery, 1960.

The Ether Vapor was also produced as a variant ofthe Halothane Vapor to appease the supporters ofether anaesthesia and a further variant on theEther Vapor was also produced which could either

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be built into the flow control section of Octavianor attached to older anaesthetic machines.During ongoing development, the ether vaporiz-er was removed from the original Circle System(see page 56) and replaced with a second absorb-er. In this way, Dräger engineers brought theCircle System up to date for halothane technolo-gy as Circle System IV.

In response to pressure from its overseasagents for a Boyle machine, Dräger producedthe Tiberius anaesthetic machine in 1961. Itwas made in a way that was characteristic ofthe British school of anaesthesia. Tiberius hadfour legs and a table top with a cross-beamover it on which the vaporizers for the differentanaesthetic agents – switched in series – couldbe mounted. As a special Dräger feature,Tiberius could have a Vapor installed on thetable top and also a small cupboard with draw-ers to house accessories.

The three Agrippa models produced at the startof the Fifties were now outdated, but modernis-ing their relatively simple, and therefore inex-pensive, column design was considered worth-while so that Sulla was produced in 1963. It wasa basic unit which could be adapted to suitdifferent users with various additional items ofequipment:

Cyclopropane (as a third gas), ether vaporizer,Halothane Vapor, semi-open systems of differenttypes, Circle System III or IV, manual ventilationfacility and Pulmomat.

Operating diagram forCircle System III …

… and Circle System IV.

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In 1961, Dräger introduce theTiberius anaesthetic machine,continuing the successful„Roman emperor“ series.

The modular concept was so popular and so suc-cessful that Sulla became the top-selling anaes-thetic machine in Europe in the years whichfollowed.

The modern operating theatreDuring the early Sixties, facilities for anaesthesiabecame more and more sophisticated for bothpatient and anaesthetist. For example, there was asteady trend for hospitals to provide for inductionand recovery to take place in separate induction

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Sulla anaesthetic machine,1963.

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and recovery rooms next to the operating theatre,rather than in the theatre itself. This meant thatthe induction room also had to have an anaesthet-ic machine and, since space was usually at apremium, Dräger realised in 1966 that it madegood sense to bring together all the fittings neces-sary for anaesthesia induction – that is flowmeterblock, Vapor and Circle System – on a fixture

In 1963, Dräger introducetheir first wall-mountedanaesthetic machine.

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which was firmly mounted on the wall. Hence thefirst Dräger wall-mounted anaesthetic machinewas born. It was supplied with oxygen and nitrousoxide from a central medical gas pipeline systemwhich was in widespread use by then.

The space-saving concept was taken further by aHamburg architect who was designing a new,large hospital. His plans required an anaestheticmachine „built into the wall“ and so anotherversion, the Dräger wall-fitted anaesthetic ma-chine, was launched in 1966.

In 1966, Dräger launched awall-fitted anaestheticmachine for building-in inhospitals.24

939

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This machine consisted of a painted steel (laterstainless steel) insert about 13 cm deep with theusual anaesthetic equipment fitted flush into atiled wall.

Anaesthetic developments in the field of ventila-tion – particularly in intensive care treatment –meant that the Spiromat 5000 anaesthetic ma-chine had to be completely redesigned.Drägerwerk launched the Spiromat 650 anaes-thetic machine in 1966. This sizeable machine(enormous by today’s standards) met all thetechnical requirements of ventilation practice atthe time.

A selection of the options for settings it offeredduring, after, or even independently of, anaesthe-sia are listed below:

� controlled ventilation � assisted ventilation � tidal volumes from 20 to 1500 ml per stroke � ventilation frequency from 8 to 70 per minute � electrically-controlled ventilation frequency � ventilation pressures adjustable from -15 to

+100 mbar � controllable mean airway pressure � adjustable ventilation pressure waveform � ventilation time ratio (inspiration:expiration)

selectable from 1:1 to 1:4

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New in 1966: the Dräger Anaes-thetic Spiromat 650 was the re-sult of the ongoing developmentof the Anaesthetic Spiromat5000, which dated back to 1959.

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Mobile anaesthetic machinesAnaesthetic apparatus for use in the field datesback to the 1914-1918 war and has a special placein the history of anaesthetic machines at Dräger.Only a few specimens of the Roth-Dräger hand-held 145 N device were likely to have been used inGerman Army field hospitals. (It was packed in awooden case and could be connected to a standard10 L oxygen cylinder.)

It is probable that more widespread use wouldhave been hampered by the difficulties in suppliesof oxygen. Whilst the British used their OxfordVaporizer (ether/air in a draw-over system) andthe Americans had their Heydbrinck (oxygen/nitrous oxide/ether in a circle system) even infront-line field hospitals, little is known aboutGerman anaesthetic field apparatus during the1939-1945 war.

After the end of the war in 1948, Drägerwerkreceived its first order to develop anaesthetic fieldapparatus – from the French Occupation Army.The apparatus was built to the instructions of aFrench field surgeon stationed in Baden-Baden,who was interested in anaesthesia. The result wasthe Model L portable anaesthetic apparatus whichused oxygen/nitrous oxide/ether in a circle systemand could be dismantled. About 120 applianceswere supplied at that time, all under reparationrequirements, not as foreign currency earners.

Only with the founding of the Bundeswehr (Feder-al Army of the Federal Republic of Germany) in theFifties did young anaesthetists with experience

Anaesthesia machinesfor special use

75

from the war years begin to demand modernanaesthesia methods, and equipment to match, forfront-line surgical units.

The most important name that must be mentionedis that of Professor Rudolf Frey, then Senior Physi-cian for Anaesthesia at the Surgical UniversityClinic in Mainz and adviser to the Bundeswehr.The Small Field Anaesthetic Apparatus wasproduced as the result of close co-operation with

Known as the Ether Cato forshort, the „Small Field“anaesthetic machine, 1958.41

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the relevant Development Unit in the BundeswehrProcurement Office in Koblenz. Inside Dräger thiswas called the Ether Cato for short. Dräger choseto produce a machine which was similar to theEnglish EMO for three reasons:

1. It was important to eliminate supply problems foroxygen;

2. Small, easy-to-pack apparatus was required whichwas maintenance free;

3. The design had proved itself in British use.

After extensive trials, the apparatus was firstdelivered to the Bundeswehr in 1958, and by 1962,750 had been supplied.

From the outset, all the experts had agreed thatthe First Aid apparatus had to be followed quicklyby a full anaesthetic machine which could meet alltechnical demands, since even front-line fieldhospitals were routinely practising major surgery(including thorax surgery) from about 1950 on-wards.

As a consequence, the Large Field AnaestheticApparatus appeared very soon afterwards. To allintents and purposes, this was Fabius in functionsand use, and it was, in fact, known inside Drägeras Fabius M. However, the apparatus was designedto be dismantled and packed away with an amplesupply of accessories, ready for use in the field.Anaesthesia for children and infants was notignored either, as appropriate accessories weresupplied. Fabius M, like its civilian brother, wasbased on the principle of oxygen/nitrous oxide/

77

ether in a circle system. It could also be used forsemi-open operation, that is without soda lime.This handy equipment was supplied to the Bun-deswehr and to Civil Defence organisations at theend of 1959. By 1964 the Bundeswehr had acquiredabout 750 machines and the Civil Defence hadabout 1200.

The „Large Field“ anaestheticmachine, also known asFabius M, 1958 too.

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Unpacked and assembledready-for-use, the „SmallField“ anaesthetic machine,1967.

The „Small Field“ anaestheticmachine securely packedin a compact box for trans-port, was also known as theHalothane-Cato.

27 6

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The unstoppable move in anaesthesiology awayfrom ether to halothane, which started at thebeginning of the Sixties, also meant new thinkingfor the Bundeswehr. In 1966 the result was a newsmall anaesthetic field machine, known insideDrägerwerk as the Halothane Cato 10. The halo-thane vaporiser was based on the Vapor principle,but it was modified for the „draw-over system“ toreduce breathing resistance in the inspiratory andexpiratory tract. An elaborate ventilation valvewas also added to the machine so that ventilationpressures and tidal volume, measured on theVolumeter, could be controlled. The oxygen con-tent of the draw-over air could also be increasedto 30 percent, with an oxygen enrichment device,and pure oxygen could be used in an emergency.The Bundeswehr were supplied with about 1100 ofthese units over about 10 years.

A brief account of nitrous oxide in dentistryInhalation anaesthesia has played, and is continu-ing to play, an important role in hospital and fieldsurgery and also in other fields of medicine. Thisis particularly true of nitrous oxide, which wasdiscovered as an anaesthetic agent 150 years agoand first used in dental surgery. Prof Hans Killian,discussing this subject in his book „The adventureof anaesthesia“ (page 20), writes:

„There is no doubt at all that nitrous oxide anaes-thesia is actually the oldest anaesthetic processsince it was discovered by Horace Wells, a dentistwho wanted to make prostheses and had beenlooking for an anaesthetizing agent so that stumpsand decayed teeth could be extracted painlessly,

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In 1928, Drägerwerk devel-oped models B and C for usein dentistry. 99

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since this was an essential preliminary to theproduction of dentures. If he was forced to pullteeth out without numbing the pain when thepatient was fully conscious, the patient was liableto take his money and run well before the prosthesiswas ready“.

It is also known that Professor Hans Pflüger, thenHead of the Teaching Hospital for Dentistry andOrthodontics at Eppendorf in Hamburg, was thefirst to promote nitrous oxide as an anaestheticagent in dental surgery. He urged Drägerwerk toproduce a suitable, simplified version of Model A,based on the version which he knew and had beenusing in the Eppendorf surgery, and, as a result, anitrous oxide anaesthetic machine for dentistry,known as Model B, was launched at the very endof the Twenties.

This machine soon found its way into dentalsurgeries as well as into teaching hospitals. Thecomplete freedom from pain and mental stress,even during lengthy surgery, was an extremelyimportant benefit for both patient and dentist. Thefact that patients woke quickly from the anaesthet-ic, with no side effects, was also very beneficial.

Model B operated with oxygen and nitrous oxidein a semi-open system. A small, simple ether drip-feed device could also be used to deepen anaes-thesia when necessary. A machine without thisadditional ether device was marketed as Model C.

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This Model D nitrous oxideanaesthetic machine wasused in dental surgeries afterthe Second World War.

From 1936 onwards both machines experienced aboom which was brought to a halt by the outbreak ofwar. Although nitrous oxide and oxygen both contin-ued to be available, the manufacture of the machineswas prohibited as „not essential for the war effort“.

In 1946, a new beginning in dental nitrous oxideanaesthesia was made in Germany with Model D.Identical in function with Model B/C, Model Ddiffered only in the way it was made, which wasinfluenced by the availability (or, rather, non-availability) of certain materials in the early post-war years.

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The photo shows theLübeck dentist, Dr HartwigDrücke, at work in 1948 –an extraction under nitrousoxide anaesthesia withModel D.

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The Model K nitrous oxideanaesthetic and analgesiamachine, 1952.

To assist the dentist, or the assistant in charge of theanaesthetic machine to deliver the correct dose ofgas, an automatic system for controlling the flow tothe lung was incorporated in Model K from 1952.This was, in fact, a system that had been used inDräger breathing equipment as early as 1903. Withthis automatic pneumatic system, the operatormerely had to set the oxygen concentration requiredon a scale in volume percent. The total volume wasthen adjusted automatically to each tidal stroke.

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A demand valve of this kind was, of course, muchmore complicated to make than a constant flowcontrol system. Nevertheless, in 1954 Drägerwerkstill decided that it was appropriate to give Model Ka more attractive exterior to harmonise with the

Model K2, 1954, one of thelast nitrous oxide anaestheticand analgesia machines usedin dentistry.

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environment of the dental surgery. This modifiedversion, which was identical in function withModel K, was known as Model K2.

As the element of risk involved in the use of fullnitrous oxide anaesthesia in dental practice be-came more widely understood in the early Fifties,a number of experienced pioneers began to exploitthe preliminary stage of anaesthesia, i.e. analge-sia. The Zurich dentist, Dr Paul Vonow, was one ofthese. In 1953 he designed a simple and relativelyinexpensive machine in co-operation with Dräger-werk. This was the nitrous oxide analgesia ma-chine, Marius.

Marius operated with a constant flow controlsystem for oxygen and nitrous oxide (but no

The Marius simple nitrousoxide analgesia machine,1953. 16

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ether!), but with a minimum limit value for oxygenand a maximum limit value for N2O, so that theoxygen concentration administered could not dropbelow 20 vol.%. Models D, K and K2 were largelyreplaced by this machine in the years that followedand Marius maintained its position in both thedomestic and foreign market right up to the mid-dle of the Sixties.

Thereafter the rather complicated machinery forgas anaesthesia and analgesia in dental practicewas overtaken, and then replaced, by injectionanaesthesia, a process which has itself becomemore sophisticated over the years.

Fitted with a different flow control system andappropriate masks, Marius was also used for minorsurgery and in ENT departments as a small anaes-thetic machine for routine operations. In this form,it was known as the Pavor.

Nitrous oxide analgesia in obstetricsOne other area of inhalation anaesthesia in whichDräger has played a role is that of nitrous oxide/oxygen analgesia for pain relief during childbirth.Professor Gauss, a gynaecologist from Würzburg,suggested the idea of designing a special machineto Drägerwerk (1939/40). The War prevented theco-operation proceeding beyond the first prototype– one which was, nevertheless, used very success-fully at Würzburg.

It was 1950 before Dräger was able to return tothis area and then several German gynaecologistsbecame involved in developments. The result was

The New Zealander,

Hilary, and his team are

the first to conquer the

8840 metre summit of

Mount Everest. An expedi-

tion to conquer the

highest mountain in the

world would have been

unthinkable in 1953

without the use of breath-

ing equipment.

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Model E nitrous oxide anaes-thetic machine for childbirth,for obstetric use, 1951.

the Model E nitrous oxide anaesthetic machine forchildbirth which was based on experience gainedwith Professor Gauss’s prototype. In its design andfunction, the demand valve was very similar toModel K and it was extremely easy and safe to

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Model H nitrous oxide anaes-thetic machine, 1952, light-weight version.

use. The machine was placed at the patient’sbedside by a doctor or midwife who opened theoxygen and nitrous oxide cylinders and set arelatively high oxygen concentration. After a briefexplanation, the patient could be left to use themachine herself. When she felt the next contrac-tion, she could hold the mask to her face andbreathe through it calmly. The fast-acting analge-sia would provide pain relief after a few breaths.The patient could then decide for herself when toremove the mask – until the next contraction.

The midwife could also provide effective pain relieffor the patient during the actual childbirth, withoutthe analgesia impairing the patient’s ability to co-operate. An ether accessory could provide fullanaesthesia if required for a surgical procedure,such as an episiotomy following childbirth.

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Model E2 nitrous oxide anal-gesia and anaestheticmachine, 1957, at a bedsideproviding pain relief duringchildbirth.

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The modern clinical conceptsof wall-mounted machinesfound acceptance also ingynaecology: wall-mountedModel E2 nitrous oxide anal-gesia and anaesthetic ma-chine, 1964.

Demand was also growing for this type of painrelief to be available for home births and all thatwas required was a portable version. In 1952Dräger met this demand with Model H, which washoused in a convenient light metal case, whichalso included one 2 L cylinder each of oxygen and

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nitrous oxide. A trolley and standard 10 L cylin-ders were provided for ward use.

In due course, Model E became Model E2through a process of minor modifications andtechnical „cosmetics“, though it was identical toits predecessor as far as function and use wereconcerned.

The E2 wall-mounted model, marketed in 1964,also differed from the E2 version only in itsappearance. It was launched in response to callsto „move it away from the floor“ and „no moreawkward gas cylinders on the machine“. It wasmounted at a suitable point on the wall close to

Trichloroethylene Inhaler,„Göttinger Model“. 15

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Trichloroethylene inhaler forpain relief during childbirth.

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Trichloroethylene inhaler fordental anaesthesia.

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the patient and supplied with oxygen and nitrousoxide from a medical gas pipeline system.

Soon after, at the beginning of the Fifties, trichlo-roethylene in its pure form which was suitable„pro narcosi“ played a secondary role in obstet-rics and dentistry, namely as an analgesic forpain relief during childbirth and painful dentaltreatment. It was applied with the simplest ofinhalers, and inhaled by mouth or by nose.Trichloroethylene Drägerwerk participated inthis – in inhaler for dental hindsight – short-livedfashionable anaesthesia idea with its „Göttingermodel“ (following the concepts of Prof Hosemannand Dr Hickl) as well as the analgesic „Trimenth“(in ampoules) which was a highly refined trichlo-roethylene with menthol added to mask theodour.

The outcome of progress in electronics andelectrotechnology in the technical developmentof Dräger’s anaesthetic machines will be de-scribed in Volume II of our chronicle. It willcover the recent past and will bring this histori-cal view of 100 years of Dräger anaesthetictechnology to a close.

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1889 Invention of pressure regulator; asbeer pressure controller and oxy-gen controller, the pressure regula-tor laid the foundations of Dräger-werk’s successPage 10/11

1902 German Reich patent for drip-feedapparatusPage 12

1902 Development of first anaestheticapparatus in Germany: hand-heldapparatus 145 N, also known asthe Roth-DrägerPage 14

1910 Roth-Dräger Mixed AnaestheticApparatusPage 16

1911 A world first: anaesthetic machinewith artificial ventilation, the Roth-Dräger-KrönigPage 20

1912 Dräger-Combi, a new type of com-bination for mixed anaesthesia,positive pressure anaesthesia andartificial respirationPage 23

1924 Development of the first circle sys-tem in the world, initially used fornarcylenePage 30

1926 Model A, the first batch-producedcircle system for nitrous oxidePages 31/32

Chronological survey

1928 Models B and C, specially for usein dental surgeriesPages 80/81

1934 Tiegel-Dräger anaesthetic appara-tus for anaesthesia with superheat-ed ether vapourPage 35

1935 Type MU positive pressure mixedanaesthetic apparatusPages 38/39

1946 Model D oxygen-nitrous oxide an-aesthetic machine; a move to-wards a new ergonomic approachin the development of anaestheticapparatus; for the first time, mostcontrols are fitted in a consolePages 41, 82/83

1948 Model F anaesthetic machine foroxygen, nitrous oxide and ether;with bronchial suction which isindependent of motor or electricpowerPage 41

1950 Model G, designed specially forthe international market, with theoption of connecting up to fivegasesPage 44

1951 Model E nitrous oxide anaestheticmachine for use during childbirth,in obstetrics; almost identical withModel KPage 88

1952 Model H a light, portable anaesthet-ic machine for home obstetric usePages 91

95

1952 Model K, for use in dental surger-ies, with built-in automatic flowcontrolPage 84

1952 Dräger introduce Romulus, a re-finement of Model F and an opti-mally ergonomic, „integrated“ an-aesthetic workstation; also availa-ble as Remus, with slight modifica-tions for the international marketPage 47

1952 Agrippa range of modelsPage 50

1952 Introduction of Dräger Pulmomat,an automatic ventilator for all an-aesthetic machines; significantlyeases the anaesthetist’s taskPage 53

1953 Marius nitrous oxide analgesia ma-chine for use in dentistryPage 86

1956 Fabius, with the recently-devel-oped Circle System II, which madepartial re-breathing possiblePage 55

1957 Model E is modified slightly andlaunched as Model E2Page 92

1958 „Small Field“ anaesthetic machine,also known as the Ether-CatoPages 75/76

1958 „Large Field“ anaesthetic machinePage 76

1958 First prototypes of Vapor, an an-aesthetic agent vaporiserPage 63

1959 Anaesthetic Spiromat 5000, anelectrically operated anaestheticmachinePage 57

1960 Octavian, with built-in Vapor forHalothane humidificationPage 65

1961 With Tiberius, the Dräger-Vaporbecomes batch producedPage 67

1963 Sulla, the successful Dräger an-aesthetic machine which remainedin production – with appropriatetechnical modifications – until 1996Page 67

1964 Model E 2 becomes available forclinical use in a wall-mounted ver-sionPage 92

1966 Anaesthetic Spiromat 650Page 72

CORPORATE HEADQUARTERSDrägerwerk AG & Co. KGaAMoislinger Allee 53–5523558 Lübeck, Germany

www.draeger.com

REGION EUROPE CENTRAL AND EUROPE NORTHDräger Medical GmbH Moislinger Allee 53–5523558 Lübeck, GermanyTel +494518820Fax +494518822080info@draeger.com

REGION EUROPE SOUTHDräger Médical S.A.S. Parc de Haute Technologie d’Antony 225, rue Georges Besse92182 Antony Cedex, FranceTel +33146115600Fax+33140969720dlmfr-contact@draeger.com

REGION MIDDLE EAST, AFRICADräger Medical GmbHBranch OfficeP.O. Box 505108Dubai, United Arab EmiratesTel +97144294600Fax +97144294699contactuae@draeger.com

REGION ASIA / PACIFICDraeger Medical South East Asia Pte Ltd.25 International Business Park#04-27/29 German CentreSingapore 609916, SingaporeTel +6565724388Fax +6565724399asia.pacific@draeger.com

REGION CENTRAL AND SOUTH AMERICADräger Panama Comercial S. de R.L.Complejo Business Park, V tower, 10th floorPanama CityTel +5073779100Fax +5073779130contactcsa@draeger.com

As of August 2015:Dräger Medical GmbH changes to Drägerwerk AG & Co. KGaA.

USADraeger Medical, Inc.3135 Quarry Road Telford, PA 18969-1042, USATel +12157215400Toll-free +18004372437Fax +12157235935info.usa@draeger.com

Manufacturer:Dräger Medical GmbH Moislinger Allee 53–5523558 Lübeck, Germany

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