| Artificial ventilation | |
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 Respiratory therapist examining a mechanically ventilated patient on anIntensive Care Unit. | |
| Other names | Artificial respiration |
| Specialty | Critical care medicine |
Artificial ventilation, also calledartificial respiration, is a means of assisting or stimulatingrespiration. Respiration is the overall metabolic process that exchanges gases in the body through pulmonary ventilation, external respiration, and internal respiration.[1][2] Artificial ventilation may take the form of manually providing air for a person who is notbreathing or is not making sufficientrespiratory effort,[3] or it may take the form ofmechanical ventilation involving the use of aventilator to move air in and out of the lungs when an individual is unable to breathe on their own, such as duringsurgery withgeneral anesthesia or when an individual is in acoma ortrauma.
Pulmonary ventilation is done by manual insufflation of the lungs either by the rescuer blowing into the patient's lungs (mouth-to-mouth resuscitation), or by using a mechanical device. Mouth-to-mouth resuscitation is also part ofcardiopulmonary resuscitation (CPR) making it an essential skill forfirst aid. In some situations, mouth to mouth is also performed separately, for instance in near-drowning andopiate overdoses.[4] The performance of mouth to mouth on its own is now limited in most protocols tohealth professionals, whereas lay first aiders are advised to undertake full CPR in any case where the patient is not breathing. This method of insufflation has been proved more effective than methods which involve mechanical manipulation of the patient's chest or arms, such as theSilvester method.[5]
Mechanical ventilation is a method to mechanically assist or replace spontaneousbreathing.[6] This involves the use ofventilator assisted by aregistered nurse,physician,physician assistant,respiratory therapist,paramedic, or other suitable person compressing abag valve mask. Mechanical ventilation is termed "invasive" if it involves any instrument penetrating through the mouth (such as an endotracheal tube) or the skin (such as atracheostomy tube).[7] There are two mainmodes of mechanical ventilation within the two divisions: positive pressure ventilation, where air (or another gas mix) is pushed into thetrachea, and negative pressure ventilation, where air is, in essence, sucked into the lungs.[8]
Tracheal intubation is often used for short-termmechanical ventilation. It's when a tube is inserted through the nose (nasotracheal intubation) or mouth (orotracheal intubation) and advanced into thetrachea. In most cases, tubes with inflatable cuffs are used to prevent leakage and aspiration. Intubation with a cuffed tube is thought to provide the best protection against aspiration. The downside of tracheal tubes is the pain and coughing that follow. Therefore, unless a patient is unconscious or anesthetized,sedative drugs are usually given to provide tolerance of the tube. Other disadvantages of tracheal intubation include damage to the mucosal lining of thenasopharynx ororopharynx and subglottic stenosis.
In an emergency, acricothyrotomy can be performed by healthcare professionals, in which an airway is inserted through a surgical opening in thecricothyroid membrane. This is similar to atracheostomy, but acricothyrotomy is reserved for emergency access. This is usually only used when there is a complete blockage of thepharynx, or there is massive maxillofacial injury, preventing other adjuncts from being used.[9]
A rhythmic pacing of the diaphragm is caused with the helpof electrical impulses.[10][11] Diaphragm pacing is a technique used by persons with spinal cord injuries who are on a mechanical ventilator to aid with breathing, speaking, and overall quality of life. It may be possible to reduce reliance on a mechanical ventilator with diaphragm pacing.[12] Historically, this has been accomplished through the electrical stimulation of aphrenic nerve by an implanted receiver/electrode,[13] though today an alternative option of attachingpercutaneous wires to the diaphragm exists.[14]
The Greek physicianGalen may have been the first to describe artificial ventilation: "If you take a dead animal and blow air through its larynx through a reed, you will fill its bronchi and watch its lungs attain the greatest distention."[15]Vesalius too describes ventilation by inserting a reed or cane into thetrachea of animals.[16]
It wasn't until 1773, when an English physicianWilliam Hawes (1736–1808) began publicizing the power of artificial ventilation to resuscitate people who superficially appeared to have drowned. For a year he paid a reward out of his own pocket to any one bringing him a body rescued from the water within a reasonable time of immersion.Thomas Cogan who was another English physician had become interested in the same subject during a stay atAmsterdam.
In the summer of 1774, Hawes and Cogan each brought fifteen friends to a meeting at the Chapter Coffee-house inSt Paul's Churchyard, where they founded theRoyal Humane Society. Some methods and equipment were similar to methods used today, such as wooden pipes used in the victims nostrils to blow air into the lungs. Or the use of bellows with a flexible tube for blowing tobacco smoke through the anus to revive vestigial life in the victim's intestines, which was discontinued with the eventual further understanding of respiration.[17]
The work of English physician and physiologistMarshall Hall in 1856 suggested against the use of any type of bellows/positive pressure ventilation. These views that were held for several decades. The introduction of a common method of external manual manipulation in 1858, was the "Silvester Method" invented byHenry Robert Silvester. A method in which a patient is laid on their back and their arms are raised above their head to aid inhalation and then pressed against their chest to aid exhalation. In 1903, another manual technique, the "prone pressure" method, was introduced by SirEdward Sharpey Schafer.[18] It involved placing the patient on his stomach and applying pressure to the lower part of the ribs. It was the standard method of artificial respiration taught in Red Cross and similar first aid manuals for decades,[19] until mouth-to-mouth resuscitation became the preferred technique in mid-century.[20]
The shortcomings of manual manipulation led doctors in the 1880s to come up with improved methods of mechanical ventilation, which includedDr. George Edward Fell's "Fell method" or "Fell Motor."[21] It consisted of a bellows and a breathing valve to pass air through atracheotomy. He collaborated with Dr.Joseph O'Dwyer to invent the Fell-O'Dwyer apparatus, which is a bellows instrument for the insertion and extraction of a tube down the patientstrachea.[22][23] Such methods were still looked upon as harmful and were not adopted for many years.
In 2020, the supply of mechanical ventilation became a central question for public health officials due to2019–20 coronavirus pandemic related shortages.
Media related toArtificial respiration at Wikimedia Commons
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