Minnitt Apparatus

WLMD ID: ainj
When Dr. Robert James Minnitt (1889-1974) began his medical career in 1915, most of Great Britain’s poor and working-class women gave birth at home with the aid of a midwife. Because the popular ‘twilight sleep’ for labor pain was administered only by physicians, effective pain relief during childbirth was generally not available to these women. Dr. Minnitt’s refusal to accept this disparity inspired him to work with A. Charles King (1888-1966), a prominent English manufacturer of anesthetic equipment, to develop a nitrous oxide (N2O) delivery device that could be carried by midwives into the homes of the women they cared for. Minnitt and King adapted a McKesson device, likely the Nargraf, to create a machine that could be used by the patient to self-administer a mixture of air and N2O. The Minnitt Apparatus was introduced in 1933 and approved by a British oversight authority, the Central Board of Midwives, in 1936. The size of the machine allowed a midwife to place it into a basket on her bicycle for transport. The N2O cylinders however were very heavy and coordinating their delivery to a woman’s home was sometimes a hindrance. Obtaining the funds for the purchase and maintenance of the machines could also present challenges. Despite these difficulties, for many years the Minnitt Apparatus provided the only means of analgesia to millions of British women in labor.

Catalog Record: Minnitt Apparatus

Access Key: ainj
Accession No.: 2007-03-20-1 B

Title: [Minnitt apparatus / designed by R.J. Minnitt and A. Charles King.]

Author: Minnitt, Robert James, 1889-1974.
Author: King, A. Charles, 1888-1966.

Title variation: Alt Title
Title: Minnitt’s gas-air apparatus : portable model.

Title variation: Alt Title
Title: Minnitt “midwives’ model”.

Title variation: Alt Title
Title: Minnitt nitrous oxide/air analgesia apparatus.

Publisher: London : A. Charles King, Ltd, [1933-1939].

Physical Description: 1 anesthesia apparatus ; nickel plated brass, rubber, leather, metal : 25 x 15 x 16.5 cm + 56 x 34 x 18 cm. case.

Subject: Anesthesia, Obstetrical.
Subject: Analgesia, Obstetrical.
Subject: Nitrous Oxide.
Subject: Self Administration.
Subject: Midwifery.

Note Type: General
Notes: Title from the WLM name for the object; Alternate titles based on articles by
Minnitt (1934 ; 1936), and Thomas (1975).

Note Type: Citation
Notes: Barnett R. “The future of the midwife depends on her power to relieve pain”.
The rise and fall of the Analgesia in Childbirth Bill (1949). Int J Obstet
Anesth. 2007;16(1):35-39.

Note Type: Citation
Notes: O’Sullivan EP. Dr Robert James Minnitt 1889-1974: a pioneer of inhalation
analgesia. J R Soc Med. 1989;82(4):221-222.

Note Type: Citation
Notes: Maltby JR. Minnitt gas and air apparatus : Robert James Minnitt (1889-1974).
Notable Names in Anaesthesia. London: Royal Society of Medicine Press,
2002:144-146.

Note Type: Citation
Notes: Minnitt RJ. Self-administered analgesia for the midwifery of general practice
Proc R Soc Med. 1934;27(10):1313-1318.

Note Type: Citation
Notes: Minnitt, RJ. Gas-air analgesia. Br J Anaesth. 1936;14(1):37.

Note Type: Citation
Notes: Thomas KB. The Development of Anaesthetic Apparatus. London: Blackwell
Scientific, 1975:232-239.

Note Type: Physical Description
Notes: The apparatus consists of a reducing valve, two connections for nitrous-oxide
tanks, a pressure gauge, cylindrical drum, a channel for both the passage of
nitrous oxide and the entrance of room air, and a connection for tubing to
the mask; The pressure gauge is marked from 0 to 120 in increments of twenty;
Manufacturer’s markings on the gauge: “REDUCED PRESSURE [new line] A.C. KING
LTD [new line] LONDON”; Manufacturer’s markings on the apparatus just above
the drum: “A530”; Manufacture’s markings on the drum: “A. CHARLES KING LTD
[new line] 34 DEVONSHIRE ST [new line] LONDON [an inch below] REG. No.
791617”; The mask consists of metal tubing and a red rubber oronasal mask;
Markings on the mask: “A. CHARLES KING”; The accompanying carrying case is
leather and metal with two manufacturers’s marked plates fastened to the top:
“PHILIP HARRIS & CO [new line] (1913) LIMITED [new line] BIRMINGHAM, ENGLAND”
[and] “A. CHARLES KING LTD [new line] DEVONSHIRE STREET, LONDON”.

Note Type: Reproduction
Notes: Photographed by Mr. William Lyle, 7/27/2010.

Note Type: Historical
Notes: When Dr. Robert James Minnitt (1889-1974) began his medical career in 1915,
most of Great Britian’s poor and working-class women gave birth at home with
the aid of a midwife. And because anesthesia for labor pain (‘twilight
sleep’) was administered only by physicians, effective pain relief during
childbirth was generally not available to these women (Barnett, 2007). Dr.
Minnitt’s refusal to accept this disparity inspired him to work with A.
Charles King (1888-1966), a prominent English manufacturer of anesthetic
equipment, to develop a nitrous oxide (N2O) delivery device that could be
carried by midwives into the homes of the women they cared for (O’Sullivan,
1989). Minnitt and King adapted a McKesson Nargraf to create a machine, with
one rather than two pressure reducing valves, that once set up by the midwife
could be used by the patient to self-administer a mixture of air and N2O
(Minnitt, 1934). Apparatus was introduced in 1933 and approved by a British
oversight authority, the Central Board of Midwives, in 1936 (Barnett, 2007 ;
Maltby, 2002). The size of the machine allowed a nurse midwife to place it
into a basket on her bicycle for transport. The N2O cylinders however were
very heavy and coordinating their delivery to a woman’s home was sometimes a
hindrance. Obtaining the funds for the purchase and maintenance of the
machines could also present challenges (Barnett, 2007). Despite these
difficulties, for many years the Minnitt Apparatus provided the only means of
analgesia to millions of British women in labor (O’Sullivan, 1989).

Note Type: Publication
Notes: Stovin GHT. Gas and Air Analgesia in Midwifery. London: Staples Press;
1944:36-48.