British Journal of Anaesthesia, 2000, Vol. 85, No. 6 928-935
© 2000 The Board of Management and Trustees of the British Journal of Anaesthesia
The inventions of John Blease
Department of Anaesthetics, Royal Infirmary, Lauriston Place, Edinburgh EH3 9YW, UK
Accepted for publication: July 26, 2000
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Abstract |
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 Top Abstract IntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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Though he had no formal training in engineering, John Blease of Merseyside invented numerous devices that greatly benefited the practice of anaesthesia. Starting with the turning of component parts for simple anaesthetic machines in the 1930s, he was introduced to clinical anaesthesia and became skilled in the art of dental anaesthesia. In the early 1940s he developed the all-purpose Alfo-Blease anaesthetic machine. In 1945 he designed an intermittent positive pressure ventilator, which was used successfully around Liverpool. After World War II he improved this into the Blease ‘Pulmoflator’, which was the first British positive-pressure ventilator in commercial production. From then until the early 1960s he patented many other inventions, duly utilized in the manufacture of anaesthetic equipment, in which industry the Blease name survives in the company he founded.
Br J Anaesth, 2000; 85; 928–35
Keywords: history, anaesthesia; history, Blease, John Henry; equipment, anaesthesia machines; equipment, ventilators
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Introduction |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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Between 1939 and 1960 John Henry Blease successfully applied for no less than 19 patents for anaesthetic equipment which he invented. Thereafter, he was involved in several more patents for inventions by Roger Manley, who had received his advice and support.
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Early days |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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John Blease was born in 1906 in Bootle and grew up in Moreton on the Wirral (Merseyside). Although he began work as a butcher’s boy at 14 yr of age, he had a mechanical mind and was brilliant at repairing clocks. Next he applied himself to tractor repairs, then became a motorcycle enthusiast, and in his late teens set up a car repair business jointly with a younger brother. In the early 1930s he built his own 1000 cc motorcycle, which he called the ‘Blease Special’ (Fig. 1). With this he entered races on sand against prestige machines and for 6 yr, beginning in 1933, he won every race in which he competed at Wallasey and Southport (personal communication, Tony and Doreen Blease).
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Anaesthetic machines |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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At this time John Blease befriended a neighbour, Dr Henry Roberts, who was a general medical practitioner and anaesthetist to the Liverpool Dental Hospital.1 At Roberts’ request, Blease made component parts from drawings of American (Gwathmey and Heidbrink) anaesthetic machines. His work impressed a full-time anaesthetist, Dr John Halton, with whom Blease also became friendly. Through these two men, Blease became acquainted with clinical anaesthesia. The improved Roberts dental anaesthetic machine (Fig. 2) became very popular and is said to have been installed in the Cunard-White Star liner Queen Mary. In 1937 Roberts died suddenly1 and his role as dental anaesthetist was taken on by Blease(!), who became highly skilled in the art. Furthermore, Blease established contact with the Liverpool surgical instrument company, Alexander and Fowler. In 1938, Blease and George Fowler applied for a patent for improvements in anaesthetic apparatus2 making use of manifold technology, valves and temperature compensation. They filed a second patent application in 19403 for the addition of carbon dioxide absorption and one-way valves. Utilization of these advances resulted in the Alfo-Blease anaesthetic machine, which was described in R. J. Minnitt’s revision of the Handbook of Anaesthetics (5th edition, 1940).4 Blease filed two more patents for improvements in 19415 and 1942;6 the latter invention was a flowmeter with a by-pass: it avoided erratic readings and allowed for a more open scale. Again these patents were incorporated in an improved model of the Alfo-Blease machine (Fig. 3). This portable apparatus included a head (rectangular metal box 6.5 in. deep x5 in. x 4.5 in.), a soda-lime cannister, a rebreathing bag and afferent and efferent corrugated tubes attached to an ‘E’ mount (with two non-return valves) for connection to the face-mask or tracheal tube. The head had three rotameters calibrated for oxygen, nitrous oxide and cyclopropane. Inside the box was an ether vaporiser with a 3-way tap and control valve, enabling the gases to either pass over or bubble through the ether.7 8 The ‘all purpose Alfo-Blease’ was well received and by 1944 Alexander and Fowler Ltd were producing 100 machines a year (price £100 each).9
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Intermittent positive pressure ventilators |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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In the early 1940s, during the World War II bombing of Liverpool, Blease was pressed into further anaesthetic service and was appointed ‘Emergency Anaesthetist’ at Birkenhead General Hospital. He even anaesthetised thoracic cases for Mr Hugh Morriston-Davies (pioneer of thoracoplasty in the UK).10 This was an astonishing achievement on two counts: first, anaesthesia in Britain was traditionally administered by physicians and, secondly, Mr Morriston-Davies would not have tolerated a ‘second best’ anaesthetic. ‘Controlled ventilation’ had been introduced into British anaesthesia in 194111 and thoracic anaesthetists became ‘bag squeezers’ when the chest was opened. Blease had plenty of time to reflect on the drudgery of manually controlled ventilation, and in 1945 he designed a pulmonary ventilator, which, with the help of Dr J. Halton, was tested successfully on patients.12 This apparatus was much appreciated when the use of d-tubocurarine in anaesthesia became more common and necessitated controlled ventilation throughout many surgical operations.13
In 1945, after World War II, Blease left the Wirral (and Alexander and Fowler) to join Multitone Electric Co Ltd, which made hearing aids, at 223–227 St John Street, London (personal communication, Tony and Doreen Blease). From this location Blease continued to supply the ‘Alfo-Blease’, imprinted with the name ‘Blease Anaesthetic Equipment Co. Ltd’. From 1946 until his retirement he resided at Royston Park Road, Hatch End, Middlesex where, in a large workshop, he did most of his inventing. In 1946 he applied for a patent for a portable mechanical ventilator,14 shown diagrammatically in Fig. 4. This was the original prototype of the Blease ‘Pulmoflator’ which operated on the ‘bag in a bottle’ principle. The driving air came from the compressor side of a rotary vacuum pump, belt-driven by an electric motor. Blease chose to purchase this, because it was smaller and cheaper than a designated compressor. The remainder of the apparatus was Blease’s invention. Within the compression chamber a blow-off valve was operated by a cam, connected by worm-gearing to the rotary pump. Adjustable spring-loaded valves controlled the minimum and maximum pressures. The frequency of cycling (respiration) was controlled by the speed of the motor, while the inspiratory: expiratory ratio was controlled by the characteristics of the cam—the disadvantage being that these were independent of pulmonary pressures. The cam and valve mechanism clearly came from car technology.
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Blease lodged another patent in 194815 (pressure pre-set ventilator) whereby the prototype was improved (Fig. 5). The cycling mechanism was changed to a spring and ratchet device (Fig. 6) reminiscent of motorcycle technology. Only one model of this early ‘Pulmoflator’ was built. To facilitate easy transport by motorcar it was made in two parts: the ‘bag in bottle’ with a ‘Blease 1 cycling box’ being the first part, and the belt driven vacuum pump the second. In 1950, Dr H. J. V. Morton (an anaesthetist at Hillingdon Hospital, Uxbridge) used it to perform controlled ventilation of patients undergoing hernia repair. He recorded pneumographs and showed that the machine could produce a respiratory pattern very close to ‘normal’, i.e. spontaneous respiration, under cyclopropane anaesthesia.16
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The ‘new Blease Pulmoflator’ (P.1) launched about the end of 1950 was the first ventilator freely available commercially in Britain. The basic workings were as described above, but the ‘bag in a bottle’ was replaced by concertina bellows in a perspex cylinder (initially not antistatic)—included in another patent applied for by Blease in 1951.17 Measurement of the tidal volume was facilitated by adjustable pointers and a calibrated scale arranged outside the perspex cylinder (Fig. 6). The clinical use of this ventilator was described in 1952.18 By 1953, driven by the need for vacuum pumps, Blease left Multitone Electric Co. and joined Edwards High Vacuum (now Edwards BOC). Operating from 12 Hinde Street, London W1, he was able to manufacture many ‘Pulmoflators’ (P.1): about three or four a month, all made one at a time! It is estimated that, over 5 yr, a total of 200 were produced; no serial numbers were issued (personal communication, Tony and Doreen Blease). In 1953, he incorporated the P.1 into a self-contained anaesthetic machine (the ‘combined pulmoflator’, P.2). This included rotameters (for oxygen, nitrous oxide, cyclopropane and carbon dioxide), racks for gas cylinders, blood pressure apparatus, suction apparatus, bronchoscope fittings, instrument trays and a metal water container.
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Other devices of use in anaesthesia |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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John Blease applied his mind to several other aspects of anaesthesia. In November 1948 he registered another two inventions at the Patent Office, London. These were an improved assembly for tracheal tubes19 and interchangeable apparatus for varying the proportion of gas flow through carbon dioxide absorbing material.20 In November and December 1950 he registered two more inventions! The first of these was a hypodermic needle with a securing transverse plate and an inclined external end for easy attachment of either a diaphragm cap or a syringe;21 the second was a double-cuffed tracheal tube.22 In 1953 he invented a device for controlling the flow of iv fluid through resilient tubing.23 Stimulated by the 1952 poliomyelitis epidemic in Copenhagen he designed a manual resuscitator, incorporating a non-return valve with no resistance to expiration. This was reviewed in 1954.24
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Improvements in pulmonary ventilation |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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Next John Blease looked again at respiration. In 1953 he designed an improved control valve for use in either an anaesthetic machine or portable resuscitation apparatus.25 In 1957, Blease moved his company to Ryefield Crescent, Northwood Hills, Middlesex where, in bigger premises, he expanded the manufacture of ‘Pulmoflators’. The same year he lodged a patent for a triggering device (Fig. 7).26 This was utilized in model P.3 which also had an injector, providing variable negative pressure during the expiratory phase.27 The P.3 was designed only for ‘open circuit’ and was intended for short or long term use in cases of respiratory paralysis/insufficiency. Next, model P.4 was designed for anaesthetic use only with a ‘closed or semi-closed circuit’. The injector was modified so that variable degrees of negative or positive pressure during expiration were possible.27 A combined ventilator/anaesthetic apparatus (model P.5) was also produced. Model P.6 of the ‘Pulmoflator’ incorporated a gauze-covered air ‘intake’, i.e. filter, so that in addition to anaesthesia, the ventilator could be used for emergency treatment of respiratory insufficiency in a hospital ward. Designed only for ‘open circuit’ it was also combined with anaesthetic apparatus—model P.7. In 1959 these ‘Pulmoflators’ were functionally analysed27—all were constant flow generators in inspiration, with pressure cycling of inspiration-expiration and time cycling of expiration-inspiration. In the expiratory phase all were pressure generators: P.1 atmospheric followed by positive pressure, P.3 constant negative pressure, P.4 and P.6 having negative and positive pressure components.
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By 1960 the Blease ‘Pulmoflator’ model P.10 was commercially available. It incorporated a large two-way valve for selection of either ‘open circuit’ or ‘closed circuit’, and had two concertina bellows units. This ‘all-purpose’ ventilator was also combined with anaesthetic apparatus—model P.11 (Fig. 8). In ‘closed circuit’ this machine operated as a P.5, and in ‘open circuit’ as a P.7. Another patent, which Blease had lodged in 1957 for a constant volume ventilator28 (Fig 9) was utilized by 1960 in ‘Pulmoflator’ models P.3—P.11. In reality this was a bellows stroke-limiting ‘stop’, which enabled tidal volume to be preset. In the successive models of ‘Pulmoflator’ the basic workings were the same: each new invention was simply added on.
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The Manley ventilator |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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In July 1960, Blease Anaesthetic Equipment Ltd filed a patent application for a new mechanical ventilator designed by Roger E. W. Manley.29 This machine incorporated two bellows in communication with each other (Fig. 10). Simultaneously, a second patent application was filed for a combination of two valves designed to improve the performance of the new ventilator.30 At that time Roger Manley was a Senior House Officer at Westminster Hospital, who had been impressed by the need for a simple, reliable and inexpensive ventilator. Using various parts including the bellows from a Blease ‘Pulmoflator’, he had assembled in the garage of his home a working model of a ventilator, powered by the fresh gases from the anaesthetic machine. Encouraged by Dr Geoffrey S. W. Organe and other anaesthetic staff at Westminster Hospital, Manley had then taken his prototype to John Blease, who agreed to develop and market it. In his paper ‘A new mechanical ventilator’ published in Anaesthesia in 1961,31 Manley thanked John Blease ‘for his continued help in developing the production model of the ventilator’. The Blease–Manley ventilator (minute volume divider) was an immediate and lasting success, many models being still in use around the world.
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Retirement |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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In his commercial endeavours John Blease was supported by his wife, Doreen, who was Company Secretary for many years (Fig. 11); his son Tony demonstrated and serviced ‘Pulmoflators’ all over the world. Perhaps not surprisingly, Roger Manley also joined the firm. John Blease decided for health reasons to retire in 1964. The Company was sold in 1965 and in 1966 moved to Deansway, Chesham, Buckinghamshire (the present address of Blease Medical Equipment Ltd). Blease remained active in retirement. In 1983, his achievements were recognised by the Liverpool Society of Anaesthetists, which elected him an Honorary Member. He died in 1985 at the age of 79 yrs.10 Modern anaesthesia owes much to his legacy of inventions!
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Acknowledgements |
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I thank Mr Tony Blease and the late Mrs Doreen Blease for their help and cooperation as well as two illustrations. Original drawings of John Blease’s patented inventions were obtained from the national patent collection in the British Library, London, which is open to the public; permission to reproduce these drawings was kindly given by Tony Blease and Blease Medical Equipment Ltd. I thank the Thackray Medical Museum and Prof. Leslie Rendell-Baker for each providing an illustration.
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References |
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TopAbstractIntroductionEarly daysAnaesthetic machinesIntermittent positive pressure...Other devices of use...Improvements in pulmonary...The Manley ventilatorRetirementReferences |
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1 Obituary of Henry Charles Roberts. Lancet 1937; 1: 782
2 Blease JH, Fowler G. Improvements in Anaesthetic Apparatus. British Patent 519,203, 1940
3 Blease JH, Fowler G. Improvements in Anaesthetising Apparatus. British Patent 535,447, 1941
4 Minnitt RJ (ed.). Handbook of Anaesthetics, 5th edn. Edinburgh: E & S Livingstone, 1940; 133–5
5 Blease JH, Fowler G. Improvements in Anaesthetizing Apparatus. British Patent 548,617, 1942
6 Blease JH, Alexander & Fowler Ltd. Improvements in Anaesthetizing Apparatus. British Patent 562,887, 1944
7 Bieber EI. An all-purpose anaesthetic machine. BMJ 1944; 1: 460
8 Minnitt RJ, Gillies J. Textbook of Anaesthetics, 6th edn. Edinburgh: E & S Livingstone, 1944; 146–8
9 Times Pictorial (Dublin), 5th February 1944
10 Gray TC. A butcher boy’s story. Anaesthetic Annotations 1997; 5: 4–5
11 Nosworthy MD. Anaesthesia in chest surgery with special reference to controlled respiration and cyclopropane. Proc R Soc Med 1941; 34: 479–506
12 Mushin WW, Rendell-Baker L, Thompson PW, Mapleson WW. Automatic Ventilation of the Lungs, 3rd edn. Oxford: Blackwell Scientific Publications, 1980: pp. 202, 216
13 Gray TC, Halton J. A milestone in anaesthesia? (d-tubocurarine chloride). Proc R Soc Med 1946; 39: 400–10[Web of Science]
14 Blease JH. Improvements in Apparatus for the Control of Respiration, Resuscitation and Anaesthesia. British Patent 625,284, 1949
15 Blease JH. Improvements in Apparatus for the Control of Respiration, Resuscitation and Anaesthesia. British Patent 649,229, 1951
16 Morton HJV. Respiratory patterns during surgical anaesthesia. Anaesthesia 1950; 5: 112–28[Medline]
17 Blease JH. Improvements in Apparatus for the Control of Respiration and Anaesthesia. British Patent 695,586, 1953.
18 Musgrove AH. Controlled respiration in thoracic surgery. A new mechanical respirator. Anaesthesia 1952; 7: 77–85[Medline]
19 Blease JH. Improved endo-tracheal assembly. British Patent 649,230, 1951
20 Blease JH. Improvements in or relating to Anaesthetic Apparatus. British Patent 653,216, 1951
21 Blease JH. Improvements in or relating to Needles for Use in Intravenous Injection. British Patent 689,131, 1953
22 Blease JH. An improved Endotracheal Tube. British Patent 693,510, 1953
23 Blease JH. Means for controlling the Flow of Liquid through Resilient Tubing. British Patent 731,988, 1955.
24 Kilpatrick A. Positive ventilation with the Blease manual resuscitator. Anaesthesia 1954; 9: 303–8[Medline]
25 Blease JH. Improved human respiration control valve. British Patent 750,152, 1956.
26 Blease Anaesthetic Equipment Ltd. Improvements in Apparatus for Assisting Respiration. British Patent 848,725, 1960.
27 Mushin WW, Rendell-Baker L, Thompson PW. Automatic Ventilation of the Lungs, 1st edn. Oxford: Blackwell, 1959; 160–8
28 Blease Anaesthetic Equipment Ltd. Improvements in apparatus for the Control of Respiration in Resuscitation and Anaesthesia. British Patent 885,221, 1961
29 Blease Anaesthetic Equipment Ltd. Improvements in Respiration Machines. British Patent 900,866, 1962
30 Blease Anaesthetic Equipment Ltd. Improvements in Valves. British Patent 908,974, 1962
31 Manley RW. A new mechanical ventilator. Anaesthesia 1961; 16: 317–23[Web of Science][Medline]
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