HOME

TheInfoList



OR:

A negative pressure ventilator (NPV) is a type of
mechanical ventilator A ventilator is a type of breathing apparatus, a class of health technology, medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to ...
that stimulates an ill person's
breathing Breathing (spiration or ventilation) is the rhythmical process of moving air into ( inhalation) and out of ( exhalation) the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxy ...
by periodically applying negative air pressure to their body to expand and contract the chest cavity.Shneerson, Dr. John M., Newmarket General Hospital, ( Newmarket, Suffolk, U.K.)
"Non-invasive and domiciliary ventilation: negative pressure techniques,"
#5 of series "Assisted ventilation" in ''
Thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...
,'' 1991;46: pp.131-135, retrieved April 12, 2020
Grum, Cyril M., MD, and Melvin L. Morganroth, MD
"Initiating Mechanical Ventilation,"
in ''
Intensive Care Medicine Intensive care medicine, usually called critical care medicine, is a medical specialty that deals with seriously or critically ill patients who have, are at risk of, or are recovering from conditions that may be life-threatening. It includes p ...
'' 1988;3:6-20, retrieved April 12, 2020
Rockoff, Mark, M.D.
"The Iron Lung and Polio,"
video (8 minutes), January 11, 2016, OPENPediatrics and Boston Children's Hospital on
YouTube YouTube is an American social media and online video sharing platform owned by Google. YouTube was founded on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim who were three former employees of PayPal. Headquartered in ...
, retrieved April 11, 2020 (historical background and images, explanatory diagrams, and live demonstrations)
"The Iron Lung,"
Science Museum Group The Science Museum Group (SMG) consists of five British museums: * The Science Museum in South Kensington, London * The Science and Industry Museum in Manchester * The National Railway Museum in York * The Locomotion Museum (formerly the Na ...
, Kensington,
London, England London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...
, U.K., retrieved April 11, 2020
"How Does Iron Lung Work?: Polio Survivor, 82, Among Last to Use Breathing Equipment,"
August 21, 2018, ''
Newsweek ''Newsweek'' is an American weekly news magazine based in New York City. Founded as a weekly print magazine in 1933, it was widely distributed during the 20th century and has had many notable editors-in-chief. It is currently co-owned by Dev P ...
'' retrieved April 11, 2020
Jackson, Christopher D., MD, Dept. of Internal Medicine, and Muthiah P Muthiah, MD, FCCP, D-ABSM, Assoc. Prof. of Medicine, Div. of Pulmonary / Critical Care / Sleep Medicine, Univ. of Tennessee College of Medicine-Memphis, et.al.
"What is the background of the iron lung form of mechanical ventilation?,"
April 11, 2019, Medscape, retrieved April 12, 2020 (short summary of iron history and technology, with photo)


Description

In most NPVs (such as the
iron lung An iron lung is a type of negative pressure ventilator, a medical ventilator, mechanical respirator which encloses most of a person's body and varies the air pressure in the enclosed space to stimulate breathing. It assists breathing when Musc ...
in the diagram), the negative pressure is applied to the patient's torso, or entire body below the neck, to cause their chest to expand, expanding their lungs, drawing air into the patient's lungs through their
airway The respiratory tract is the subdivision of the respiratory system involved with the process of conducting air to the alveoli for the purposes of gas exchange in mammals. The respiratory tract is lined with respiratory epithelium as respiratory ...
, assisting (or forcing) inhalation. When negative pressure is released, the chest naturally contracts, compressing the lungs, causing exhalation. In some cases, positive external pressure may be applied to the torso to further stimulate exhalation. Another form of NPV device (such as the Pulmotor) is placed at the patient's airway, and alternates negative pressure with positive pressure to pump air into their lungs (inhale under positive pressure), then suck it back out (exhale under negative pressure).Bottrell, John
"1907: The first mechanical ventilator: The Pulmotor,"
April 19, 2017, ''Asthma History'' blog, retrieved April 12, 2020
"Draeger Pulmotor"
Wood Library-Museum of Anesthesiology
"The Return of the Pulmotor as a 'Resuscitator': A Back-Step toward the Death of Thousands,"
by Yandell Henderson, December 1943, ''
Science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...
.''
Bahns, Ernst,
''It began with the Pulmotor: One Hundred Years of Artificial Ventilation''
Dräger Medical AG & Co. KG, Lübeck, Germany (original manufacturers of the Pulmotor).


Usage

Negative pressure ventilators, while widely used in the early-to-mid 20th century (particularly for victims of the polio epidemics), are now largely replaced by positive-pressure airway ventilators, which force air (or oxygen) directly into the patient's airway. However, researchers and clinicians still find some uses for NPVs, owing to their specific advantages. Research and developments in artificial ventilation, both negative-pressure and positive-pressure, result in evolving assessments of the benefits and hazards of negative-pressure ventilators (NPVs). Different researchers and clinicians have made varying assessments, over time, about the primary positive and negative aspects of NPVs. A sampling includes:


Advantages

Generally, NPVs are best with patients who have neuromuscular diseases, but normal lung compliance (a measure of the lungs' ability to expand and contract). They are effective for various conditions, especially neuromuscular and skeletal disorders, particularly for long-term night-time ventilation. They are effective in patients who have severe
respiratory acidosis The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gr ...
, impaired consciousness, are unable to tolerate a facial mask (due to facial deformity, or claustrophobia, or excess airway secretions), and in children.Corrado, A.; Gorini, M.:
"Negative-pressure ventilation: is there still a role?,"
'' European Respiratory Journal'' 2002, 20: pp.187-197;, also i
PDF
retrieved April 17, 2020
Continuous external negative pressure ventilation (CENPV) was found in a 2015 study to " mproveoxygenation under greater number ofphysiological conditions", concurrent with lower "airway," "transpulmonary," and "intra-abdominal" pressures, than experienced with continuous
positive pressure ventilation Positive airway pressure (PAP) is a mode of Modes of mechanical ventilation, respiratory ventilation used in the treatment of sleep apnea. PAP ventilation is also commonly used for those who are critically ill in hospital with respiratory failure ...
(CPPV), in study of adult respiratory distress syndrome (ARDS) patients, possibly reducing high ARDS mortality.Raymondos, Konstantinos; Jörg Ahrens; Ulrich Molitoris
"Combined Negative- and Positive-Pressure Ventilation for the Treatment of ARDS"
in '' Case Reports in Critical Care'' 2015; 2015: 714902. Published online July 28, 2015, from NCBI,
National Institutes of Health The National Institutes of Health (NIH) is the primary agency of the United States government responsible for biomedical and public health research. It was founded in 1887 and is part of the United States Department of Health and Human Service ...
, retrieved April 12, 2020.


Disadvantages

NPVs do not work well if patient's lung compliance is decreased, or their lung resistance is increased. They result in a greater vulnerability of the airway to aspiration, such as inhalation of
vomit Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, pregna ...
or swallowed liquids, than with intermittent positive pressure ventilation. They exacerbate obstructive
sleep apnea Sleep apnea (sleep apnoea or sleep apnœa in British English) is a sleep-related breathing disorder in which repetitive Apnea, pauses in breathing, periods of shallow breathing, or collapse of the upper airway during sleep results in poor vent ...
. The device is not portable and its installation may be difficult. Patients must sleep in a supine position.Walkey, Allan M.D. and Ross Summer M.D., "Negative pressure" in "E. Noninvasive Mechanical Ventilation," in
Boston Medical Center ICU Manual
'' 2008, ''
Boston University Boston University (BU) is a Private university, private research university in Boston, Massachusetts, United States. BU was founded in 1839 by a group of Boston Methodism, Methodists with its original campus in Newbury (town), Vermont, Newbur ...
,'' p.17, retrieved April 12, 2020.


Types of NPVs

There are several types of NPVs, including: *
Iron lung An iron lung is a type of negative pressure ventilator, a medical ventilator, mechanical respirator which encloses most of a person's body and varies the air pressure in the enclosed space to stimulate breathing. It assists breathing when Musc ...
, also known as a tank ventilator, Drinker tank or Emerson tank; * Cuirass ventilator, also known as a chest shell, turtle shell or tortoise shell; * exovent;"Modern iron lung designed to address ventilator shortage,"
April 06, 2020, ''New Atlas,'' retrieved April 11, 2020 (note detailed reader comment, April 7, 2020, by Christopher Smith, with clinical application details.)
"The 'iron lung' and the modern 'ventilation',"
Oxy.gen, retrieved April 11, 2020
* jacket ventilator, also known as a poncho or raincoat ventilator; * ''Pulmotor''.


Iron lung

The
iron lung An iron lung is a type of negative pressure ventilator, a medical ventilator, mechanical respirator which encloses most of a person's body and varies the air pressure in the enclosed space to stimulate breathing. It assists breathing when Musc ...
, also known as the tank ventilator, Drinker tank or Emerson tank, was the first common pure-NPV device when it was developed in the 1920s by Drinker, Shaw and Mason. It is a large, sealed horizontal cylinder (or "tank") in which the patient lies, with their head protruding from a sealed opening at one end of the tank. An air pump or a flexible diaphragm (usually motor-driven) varies the air pressure inside the tank, in continuous alternations, lowering and raising the air pressure in the cylinder. This causes the patient's chest to rise and fall, stimulating inhalation and exhalation through the patient's nose and mouth (which are outside the cylinder, exposed to ambient air pressure).


Cuirass ventilator

The cuirass ventilator, also known as the chest shell, turtle shell or tortoise shell, is a more compact variation of the iron lung which only encloses the patient's torso and is sealed around their neck and waist, and depressurized and repressurized by an external pump or portable ventilator.Matioc, Adrian A., M.D.,
University of Wisconsin A university () is an institution of tertiary education and research which awards academic degrees in several academic disciplines. ''University'' is derived from the Latin phrase , which roughly means "community of teachers and scholars". Uni ...
School of Medicine & Public Health, William S. Middleton Memorial Veterans Hospital,
Madison, Wisconsin Madison is the List of capitals in the United States, capital city of the U.S. state of Wisconsin. It is the List of municipalities in Wisconsin by population, second-most populous city in the state, with a population of 269,840 at the 2020 Uni ...
, "Early Positive and Alternate Pressure Machines" in "An Anesthesiologist’s Perspective on the History of Basic Airway Management: The 'Progressive' Era, 1904 to 1960," submitted May 27, 2017, published February 2018, ''
Anesthesiology Anesthesiology, anaesthesiology or anaesthesia is the medical specialty concerned with the total perioperative medicine, perioperative care of patients before, during and after surgery. It encompasses anesthesia, intensive care medicine, critica ...
,'' Vol. 128, No 2


Exovent

The exovent is a modern device similar to the cuirass ventilator, but developed in 2020, in response to the
COVID-19 pandemic The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...
.


Jacket ventilator

The jacket ventilator, also known as a poncho or raincoat ventilator, is a lighter version of the iron lung or the cuirass ventilator, constructed of an airtight material (such as plastic or rubber) arranged over a light metal or plastic frame, or screen, and depressurized and repressurized by a portable ventilator."Poncho,"
by medical device manufacturer Dima Italia S.r.l. of
Bologna, Italy Bologna ( , , ; ; ) is the capital and largest city of the Emilia-Romagna region in northern Italy. It is the List of cities in Italy, seventh most populous city in Italy, with about 400,000 inhabitants and 150 different nationalities. Its M ...
(picture of jacket ventilator ("poncho"), and other information.), retrieved April 12, 2020


Positive-and-negative pressure ventilator


Pulmotor

The Pulmotor is a device developed in the early 1900s which was the forerunner of modern
mechanical ventilator A ventilator is a type of breathing apparatus, a class of health technology, medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to ...
s. It used pressure from a tank of compressed oxygen to operate a valve system that alternately forced air into and out of a person's airway, using alternating positive and negative air pressure. Although portable, and able to be used by lay persons and non-medical emergency responders, some medical personnel criticized it as dangerous (in part due to the risks of barotrauma or vomiting) and inefficient.


References

{{reflist


External links


''It began with the Pulmotor: One Hundred Years of Artificial Ventilation''
by Ernst Bahns, published by Dräger Medical AG & Co. KG, Lübeck, Germany (original manufacturers of the Pulmotor, and many other ventilation items, to the present day) (a lengthy, illustrated history of the development of artificial ventilation, interwoven with the publishers' own apparently self-promotional corporate history). Respiratory therapy Mechanical ventilation