Pender Lemon

WLMD ID: aiyd

Commonly referred to as the “Pender Lemon” due to its shape, Dr. John William Pender (1912-2001) designed this endotracheal inhaler in 1945, to facilitate the open-drop method of ether anesthesia for intubated patients. “Intubated” means the anesthesiologist inserted a plastic breathing tube (endotracheal tube) into the patient’s trachea (wind pipe) to maintain an open airway and assist breathing during surgery. The open-drop method involved connecting the metal tube at one end of the Pender Lemon to the patient’s endotracheal tube. Gauze was stretched over the inhaler’s wires and ether was applied to the gauze in drops, or lightly poured, so that the patient inhaled evaporated anesthetic as well as air.

Dr. Pender was the first Emeritus Clinical Professor of Anesthesiology at Stanford University. He presented this gold-plated Pender Lemon to the Wood Library-Museum of Anesthesiology in 1988. Drs. John William Pender and John Leahy encouraged and supported the WLM’s recording of peer-conducted interviews of anesthesiology’s pioneers and leaders. The John W. Pender Collection of the Living History of Anesthesiology continues to be developed by the WLM’s Living History of Anesthesiology Committee. Interviews may be viewed via the library section of the WLM website.

Catalog Record: Pender Lemon

Access Key: aiyd
Accession No.: 2011-02-15-2

Title: [Pender endotracheal vaporizer / designed by John W. Pender.]

Author: Pender, John William 1912-2001.

Title variation: Alt Title
Title: Pender lemon.

Title variation: Alt Title
Title: Gold-plated “Pender Lemon” ether device.

Title variation: Alt Title
Title: Pender’s endotracheal vaporizer.

Title variation: Alt Title
Title: Pender’s endotracheal inhaler.

Publisher: [S.l. : s.n., 1943-1946].

Physical Description: 1 inhaler ; gold plated metal; 10 x 5 dia. cm, in case 23 x 19 x 8 cm.

Subject: Inhalers, Anesthesia.
Subject: Ether, Ethyl.
Subject: Anesthesia, Inhalation.

Note Type: General
Notes: Title based on the 1945 article by Dr. Pender and Dr. Lane, and the WLM name
for the object; Alternate title based on references to the object in other

Note Type: General
Notes: The WLM holds an unfinished autobiography by Dr. Pender. Unfortunately Dr.
Pender passed before he was able to complete it. The WLM also holds a small
archive of Dr. Pender’s personal papers donated by his daughter Sarah Pender,

Note Type: Citation
Notes: Bause GS. Gold-plated “Pender Lemon” ether device. Anesthesiology.

Note Type: Citation
Notes: Calmes SH. John William “Bill” Pender, M.D. 1912-2001. Bull Anes Hist.

Note Type: Citation
Notes: Pender JW, Lane JN. An endotracheal vaporizer. Anesthesiology.

Note Type: Physical Description
Notes: An anesthesia inhaler of wire construction; The shape of the inhaler is
approx. that of a lemon; The design of the inhaler is also suggestive of the
head of an egg beater; The wires at one end of the inhaler terminate at a
metal tubular fitting for the external end of an endotracheal tube or
adapter; The tube is approx. 4 cm long and 1 to 1.5 cm in dia.; Approx. 2 cm
of the tube extends into the inhaler and approx 2 cm extends out; Extending
perpendicular to the fitting from approx. the middle of the tube is a metal
port for oxygen or an oxygen-gas combination; The entire device is gold
plated and fixed inside a framed case ; The case and frame are glass plated
and backed with paper; The inner case is lined in red velvet; The case with
frame measures approx. 23 x 18.5 x 8 cm in size; A sticker on the back of the
frame is marked, “ANGE’S FRAMING SHOP [new line] 392 SOUTH PLAZA [new line]
LOS ALTOS, CA 94022 [new line] 415/948-0478”.

Note Type: Reproduction
Notes: Photographed by Mr. William Lyle in the summer of 2010.

Note Type: Acquisition
Notes: Donated to the Wood Library-Museum by John W. Pender, MD.

Note Type: Historical
Notes: Dr. John William Pender (1912-2001) completed his anesthesia training at the
Mayo Clinic, where he also practiced and taught after WW II. Later he became
the first Emeritus Clinical Professor of Anesthesiology at Stanford
University. Pender was known as “Bill” to most of his Mayo Clinic colleagues
and as “John” to most of his Stanford colleagues. In addition to serving as a
Wood Library-Museum (WLM) trustee and co-founding the Anesthesia History
Association and the WLM Living History program, Dr. Pender’s very generous
donation endowed the program and supported the dedication of the Mayo Clinic
Room at the ASA Park Ridge headquarters. “The John W. Pender Collection of
the Living History of Anesthesiology” contains recorded interviews with
pioneers and leaders of the specialty. The collection continues to be
developed by the WLM’s Living History of Anesthesiology Committee. Interviews
may be viewed via the library section of the WLM website.

Note Type: Historical
Notes: During WW II Dr. Pender served in the Navy at Bethesda Naval Hospital. While
there he found himself primarily administering ether with a Yankauer mask
(Calmes, 2001). This method was even employed for intubated patients, which
required the anesthesiologist to hold the mask and endotracheal tube in
position for the duration of anesthesia, including through lengthy
neurosurgical procedures. Pender devised the “endotracheal vaporizer” to
replace wire frame masks for intubated patients (Pender & Lane, 1945). It was
designed to fit an endotracheal tube using an adapter. Cotton gauze was
placed over the wire frame and ether was dropped onto the gauze. In 1945 a
short description of the device was published. Pender noted that the inhaler
was especially useful when the patient was positioned on his side, face down,
or sitting up (Pender & Lane, 1945).

Note Type: Publication
Notes: Bause GS, Conlay LA, Robins J. Treasures of the WLM. ASA Newsl. 2006;70(9):11

Note Type: Publication
Notes: Historic ‘Pender Lemon’ presented to the Wood Library-Museum. ASA Newsl.