Elmer McKesson

Elmer McKesson (1881-1935)

Elmer Isaac “Ira” McKessen (1881-1935) was an inventor, physician and engineer

McKesson almost single-handedly revolutionised the use of equipment in anaesthesia including reliable pressure-reducing valves and flow meters to allow for accurate titration of gases.

He was a great proponent for nitrous oxide in anaesthesia introducing the (albeit) misguided practice of secondary saturation with nitrous oxide until reaching the endpoints of mydriasis, cyanosis and agonal breathing to indicate adequate neuromuscular paralysis.

McKesson was ahead of his time, indeed his invention of the first semi-automated anaesthesia machine occurred almost 30years prior to fully automated machines coming into fashion in the 21st century.

He established his own company McKesson Appliance Co and was heavily involved as members or founders of numerous medical societies such as the New York Society of Anaesthetists, the American Association of Anaesthetist and the International Anaesthesia Research Society.

Even at the end, McKesson was surrounded by his own inventions, helping to decide which of his many oxygenating machines would be used to ease his dyspnoea during the terminal phase of his cancer.

  • Born on March 8, 1881 at Walkerton, St. Joseph County, Indiana, USA
  • 1906 – graduates from Rush medical College in Chicago and completes an internship at Toledo Hospital in Ohio where he develops an interest in the field of anaesthesia
  • 1910 – founds the Toledo technical Appliance Company and begins to manufacture anaesthesia equipment. Invents the McKesson Intermittent Flow Apparatus which was once of the first anesthesia machines to have an automatic cut-off regulated by the patients breathing
  • 1930 – develops the McKesson Nargraf, the first anaesthesia machine to produce semiautomated anaesthetic records. Toledo technical Appliance Company becomes the McKesson Appliance Company
  • Died on February 22, 1935 at Toledo, Lucas County, Ohio

The McKesson company continues on and hires Mr John Lester Bloomheart (1897-1977)  to design its equipment although the devices continue to bear the McKesson name; some of these patents are given to his widow Martha Fredericka Hillman McKesson (1878-1973)

  • 1948McKesson Model N is released and is big departure from the Nargraf model as it now incorporates a new carbon dioxide absorber and simplified flowmeters
  • 1956 – adds cabinet style machines into his product line in order to keep up with competitors; this spawns the McKesson’s 1600 series which incorporate a transparent, double-canister carbon dioxide
  • 1962 – McKessons company is assimilated by American Cryogenics Inc

Medical Eponyms
McKesson Intermittent (1910)

Designed and developed by McKesson in 1910, the first intermittent ventilator with an automatic cut-off function which caused airflow to cease during patient exhalation and resume during inhalation. This limited wastage. The machine could also deliver nitrous oxide, oxygen and ether as single or combined agents titrated to the patient’s clinical response. McKesson urged that the patient’s pulse, respiration rate and blood pressure should be recorded every five minutes – a function later incorporated into the his Nargraf Machine

McKesson Intermittent Flow The Canadian Hospital 1927 Vol 4 Iss 7
McKesson Intermittent Flow. The Canadian Hospital 1927 Vol 4 Iss 7

McKesson Automated Nargraf (1930)

McKesson invented the Nargraf Model J, the first anaesthesia machine capable of creating semiautomated anaesthesia records. Designed in 1930 and provided patent US2035492A in 1936

Recording encompassed not only blood pressure but also tidal volume, oxygen concentration and inspiratory gas pressure with the anaesthetist being tasked with manually documenting the heart rate and respiratory rate.

Example of recording chart (1936)

McKesson Nargraf record 1936
Example of the physiologic printout from a McKesson Nargraf gas machine. Several (6) anaesthetics being displayed in the record. Numbers: 179 = pulse pressure; 181= pulse rate; 182 = respiratory rate; 190-191 = percentage of oxygen delivered; 199 = each individual breath recorded

McKesson Metabolor (1925)

McKesson filed for patent of his “Basal metabolism factor” in 1926 and was granted patent US1863929A in 1932 and become known as the “Metabolor” –

An oxygen consumption measuring apparatus comprising a carbon dioxide eliminator, a one-way valve therefrom, a one-way valve thereto, a connection away from the eliminator and between said valves for receiving pulsations of inhalation for withdrawing oxygen from the apparatus and pulsations of exhalation for delivering carbon dioxide to the apparatus…

McKesson 1926
McKesson Metabalor 1925
The McKesson Metabolor recording device 1925. Left: blueprint design; Right: operational machine

McKesson Metabolor Calculator (1934)

McKesson copyrighted a circular slide rule for estimating basal metabolism using the Metabalor machine. The Metabolor calculator was used to estimated basal metabolism by measuring the oxygen consumption of patients over 6mins and plotting this against a specialised scale.

The McKesson Metabolor Calculator
McKesson Metabolor Calculator

McKesson Oxygen tent

As its name suggests, this oxygen delivery tent was designed for patients unable to use or tolerate the oxygen mask. It incorporated a tent that was suspended over the head of the bed, a rubber sheet placed under the patient to ‘prevent oxygen from passing through the mattress and escaping the tent,’ an oxygen cylinder, an ice cabinet to cool and dry the air and a carbon dioxide absorber. McKesson’s oxygen tent was similar to many others already on the market, all limited by need for frequent maintenance and enforcement of strict fire precautions.

McKesson Oxygen Tent. – The manufacturer recommends this oxygen tent for use in the treatment of pneumonia, cardiac disease, asphyxia, follow’ing brain and chest injuries from restricted breathing, and asphyxia neonatorum. The tent proper has a capacity of 15 cubic feet and is equipped with four large noninflammable windows. It is adjustable and may be folded for transportation and storage. The capacity of the blower is 100 cubic feet free air per minute. The unit is equipped with an oxygen meter and regulator, together with a safety light which gives a warning that the oxygen is about exhausted.

J. A. M. A., June 6, 1936

In 1943 McKesson Oxygen Tents were included in the U.S. Army manuals

McKesson Oxygen tent
US ARMY Text book (Vol 3) 1943


In a period where ether and nitrous were used in combination to induce anaesthesia. However McKesson strongly advocated for the use of nitrous oxide only anaesthesia devised by dentist Gardner Quincy Colton (1814-1898) who pioneered the practice of primary saturation with nitrous oxide in anaesthesia.

This practice of nitrous oxide only anaesthesia came under scrutiny following a series of well publicised events

  • 1879 – a young Swedish woman, Ms Hannah Deal, was rendered a ‘raving maniac’ after undergoing a dental procedure under nitrous oxide. Likely secondary to hypoxic brain injury.
  • 1887 – formal alerts were issued in the US and Great Britain about the risk for insanity from nitrous-oxide anaesthetics
  • 1892 – Miss Lizzie Lots was rendered ‘insane’ and admitted to a sanitarium following a nitrous only tooth extraction. Highlighted in the “Was it love? or simply nitrous oxide gas” publication by The Cincinnati Enquirer

McKesson was concerned about the possibility of ether induced surgical shock and wanted to “eliminate the unpleasant sequelae which even a small amount of ether produces…“. He therefore introduced ‘secondary saturation anaesthesia‘ into his practice. This involved administering an additional burst of 100% nitrous oxide to an already anaesthetised patient until the patients’ pupils were dilated and agonal breathing occurred…at this point it was felt that adequate muscle relaxation had been achieved.

McKesson noted the cyanosis secondary to the hypoxia induced by his anaesthesia technique. He chose to monitor the respiratory rate, blood pressure, eye signs and muscle movement to determine when supplemental oxygen may be applied. He believed that monitoring rhythmic deep breathing (which he presumed would reflect adequate brain oxygenation) and blood pressure would guard against stroke or other consequences from such little oxygen during his cases.

So was hypoxic brain injury and admission to mental asylums one possible legacy of McKesson’s Secondary Saturation? Yes, according to Edmond ‘Ted’ Eger II (1930-2017) who recalled one urban
legend suggesting that

the IQ of the citizens of Toledo where McKesson built his machines, was less than that in other parts of the US.

Ted Egar II, 2014

This practice of secondary saturation was superseded by the introduction of safer alternatives such as ethylene, cyclopropane, and curare.

Major Publications

McKesson possessed a comprehension of physiology and physics with a rare skill in mechanics, a combination unusual in the equipment of a physician. At the beginning of the present century, the production of surgical anesthesia had become a technical procedure of little interest to thoughtful members of the profession. McKesson was one of the few individuals whose efforts served to initiate that renewal of scientific interest in anesthesia, the fruition of which is being realized at the present time

Ralph M. Waters, M.D. 1965



Eponymous terms


the person behind the name

Emergency registrar at Sir Charles Gairdner Hospital, Perth

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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