William Mapleson

William Wellesley Mapleson (1926 – 2018) 600

William Wellesley Mapleson (1926 – 2018) was an English physicist of anaesthesia

Mapleson became a renown figure in his field after his classification of the five ‘Mapleson breathing circuits’ in 1954 – a nomenclature that continues to endure till today.

Mapleson typically would claim that his fame be attributed to his knowledge of the alphabet and largely ignores the careful analysis of each system, notwithstanding his many other contributions to anaesthesia culminating in the publication of more than 100 papers.  His main research interests were mechanical ventilation and pharmacology of anaesthetic agents.

Mapleson led a long illustrious career in anaesthesia which continued well into his 90’s as an academic researcher; was the founder of the British Anaesthetic Society for which he missed only a handful of meetings, and the recipient of many awards. The Mapleson Medal honours his legacy; a truly remarkable and unassuming celebrity of British anaesthesia.

  • Born on August 2, 1926 in West Ealing London
  • 1947 – Bachelor in Physics, University of Durham
  • 1947-1949 Completed National Service in the RAF teaching radar and thereafter returned to Durham to complete a doctoral thesis on “Point discharge in atmospheric electricity
  • 1952 – Research assistant/lecturer in the Department of Anaesthetics of the Welsh National School of Medicine in Cardiff after responding to an advert “if only for the interview practice” and with initial intention to “stay for five years”
  • 1954 – Published his paper of the five anaesthetic breathing systems “Mapleson circuits” in the British Journal of Anaesthesia
  • 1958 – Founder member of the British Anaesthetic Research Society [now the Anaesthetic Research Society (ARS)]
  • 1972 – DSc thesis on the Physics of the lung and its relation to anaesthetics
  • 1973 – Professor and chair in the physics of anaesthesia in Cardiff
  • 1977 – Pask Certificate of the Association of Anaesthetists of Great Britain and Ireland
  • 1978 – Clover Medal of the Royal College of Anaesthetists. First non-physician scientist to join the board of the British Journal of Anaesthesia
  • 1991 – Officially retired however continued to spend two days a week in the department teaching and advising on research
  • 1992 – Dudley Buxton Medal of the College of Anaesthetists
  • 1996 – Elected to Honorary Fellowship of the Royal College of Anaesthetists
  • 1998Henry Hill Hickman Medal of the Royal Society of Medicine
  • 2012Macewen Medal from the Difficult Airway Society
  • Died on October 31, 2018 in London, England

Medical Eponyms
Mapleson Circuit Systems (1954)

The Mapleson Circuit Systems are used for the delivery of oxygen and anaesthetic agents and the removal of carbon dioxide during general anaesthesia.

Components include breathing tube, adjustable pressure limiting valve, reservoir bag, fresh gas flow and patient connection. Mapleson described five breathing circuits: A, B, C, D and E. A 6th circuit ‘the Jackson Rees modification of Ayre’s T-piece (F)‘ was later added in a paper by Willis, Pender and Mapleson in 1975.

Mapleson Circuit Systems 1954 BJA
Mapleson WW. Fig 1. The five semi-closed anaesthetic systems. Br J Anaesth. 1954

Mapleson’s landmark 1954 paper classified anaesthetic breathing circuits and gave rise to the nomenclature of Mapleson circuits A, B, C, D and E. This classic paper was initially regarded as a minor theoretical study by Mapleson who was awaiting volunteers for another neuromuscular relaxant study. It has since received over 296 citations and continues to be cited regularly. Mapleson often made light of the study stating:

I seem to have become the only person to make his reputation in anaesthesia on the strength of his knowledge of the alphabet

The publication brought him to the attention of the anaesthetists and marked the beginning of a career long interest in respiration during general anaesthesia as well as all aspects of pharmacology and physiology of the general anaesthetic agents used. Mapleson was also the first to demonstrate that ventilator use in adult patients in 1962 were inappropriate for use in paediatrics.

WW Mapleson Medal (2000)

Founded in 2000 by the Anaesthetic Research Society (ARS) and awarded to the speaker considered to have presented the best research in a professional manner at an ARS meeting.

WW Mapleson Medal Anaesthetic Research Society (ARS)

Major Publications



Eponymous terms


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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