Artificial ventilation | |
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Other names | artificial respiration |
Specialty | pulmonary |
Artificial ventilation or respiration is when a machine assists in a metabolic process to exchange gases in the body by pulmonary ventilation, external respiration, and internal respiration. [1] A machine called a ventilator provides the person air manually by moving air in and out of the lungs when an individual is unable to breathe on their own. The ventilator prevents the accumulation of carbon dioxide so that the lungs don't collapse due to the low pressure. [2] [3] The use of artificial ventilation can be traced back to the seventeenth century. There are three ways of exchanging gases in the body: manual methods, mechanical ventilation, and neurostimulation. [4]
Here are some key words used throughout the article. The process of forcing air into and out of the lungs is known as ventilation. The process by which oxygen is taken in by the bloodstream is called oxygenation. Lung compliance is the capacity of the lungs to contract and expand. The obstruction of airflow via the respiratory tract is known as airway resistance. The amount of ventilated air that is not involved in gas exchange is known as dead-space ventilation. [5] [ tone ]
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 of cardiopulmonary resuscitation (CPR) making it an essential skill for first aid. In some situations, mouth to mouth is also performed separately, for instance in near-drowning and opiate overdoses. [6] The performance of mouth to mouth on its own is now limited in most protocols to health 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 the Silvester method. [7]
Mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. [8] This involves the use of ventilator assisted by a registered nurse, physician, physician assistant, respiratory therapist, paramedic, or other suitable person compressing a bag 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 a tracheostomy tube). [9] There are two main modes of mechanical ventilation within the two divisions: positive pressure ventilation, where air (or another gas mix) is pushed into the trachea, and negative pressure ventilation, where air is, in essence, sucked into the lungs. [10]
Tracheal intubation is often used for short-term mechanical ventilation. It's when a tube is inserted through the nose (nasotracheal intubation) or mouth (orotracheal intubation) and advanced into the trachea. In most cases tubes with inflatable cuffs are used for protection against leakage and aspiration. Intubation with a cuffed tube is thought to provide the best protection against aspiration. Downside of tracheal tubes is the pain and coughing that follows. 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 the nasopharynx or oropharynx and subglottic stenosis.
In an emergency a cricothyrotomy can be used by health care professionals, where an airway is inserted through a surgical opening in the cricothyroid membrane. This is similar to a tracheostomy but a cricothyrotomy is reserved for emergency access. This is usually only used when there is a complete blockage of the pharynx or there is massive maxillofacial injury, preventing other adjuncts being used. [11]
A rhythmic pacing of the diaphragm is caused with the help of electrical impulses. [12] [13] 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. [14] Historically, this has been accomplished through the electrical stimulation of a phrenic nerve by an implanted receiver/electrode, [15] though today an alternative option of attaching percutaneous wires to the diaphragm exists. [16]
The Greek physician Galen 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." [17] Vesalius too describes ventilation by inserting a reed or cane into the trachea of animals. [18]
It wasn't until 1773, when an English physician William 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 at Amsterdam.
In the summer of 1774, Hawes and Cogan each brought fifteen friends to a meeting at the Chapter Coffee-house in St Paul's Churchyard, where they founded the Royal 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. [19]
The work of English physician and physiologist Marshall 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 by Henry 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 Sir Edward Sharpey Schafer. [20] 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, [21] until mouth-to-mouth resuscitation became the preferred technique in mid-century. [22]
The shortcomings of manual manipulation led doctors in the 1880s to come up with improved methods of mechanical ventilation, which included Dr. George Edward Fell's "Fell method" or "Fell Motor." [23] It consisted of a bellows and a breathing valve to pass air through a tracheotomy. He collaboratied 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 patients trachea. [24] [25] 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 to 2019–20 coronavirus pandemic related shortages.
Mouth-to-mouth resuscitation, a form of artificial ventilation, is the act of assisting or stimulating respiration in which a rescuer presses their mouth against that of the victim and blows air into the person's lungs. Artificial respiration takes many forms, but generally entails providing air for a person who is not breathing or is not making sufficient respiratory effort on their own. It is used on a patient with a beating heart or as part of cardiopulmonary resuscitation (CPR) to achieve the internal respiration.
Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. It is frequently performed in critically injured, ill, or anesthetized patients to facilitate ventilation of the lungs, including mechanical ventilation, and to prevent the possibility of asphyxiation or airway obstruction.
A ventilator is a type of breathing apparatus, a class of 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 breathe, or breathing insufficiently. Ventilators may be computerized microprocessor-controlled machines, but patients can also be ventilated with a simple, hand-operated bag valve mask. Ventilators are chiefly used in intensive-care medicine, home care, and emergency medicine and in anesthesiology.
Mechanical ventilation or assisted ventilation is the medical term for using a machine called a ventilator to fully or partially provide artificial ventilation. Mechanical ventilation helps move air into and out of the lungs, with the main goal of helping the delivery of oxygen and removal of carbon dioxide. Mechanical ventilation is used for many reasons, including to protect the airway due to mechanical or neurologic cause, to ensure adequate oxygenation, or to remove excess carbon dioxide from the lungs. Various healthcare providers are involved with the use of mechanical ventilation and people who require ventilators are typically monitored in an intensive care unit.
Tracheotomy, or tracheostomy, is a surgical airway management procedure which consists of making an incision (cut) on the anterior aspect (front) of the neck and opening a direct airway through an incision in the trachea (windpipe). The resulting stoma (hole) can serve independently as an airway or as a site for a tracheal tube or tracheostomy tube to be inserted; this tube allows a person to breathe without the use of the nose or mouth.
Intensive care medicine, also 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 providing life support, invasive monitoring techniques, resuscitation, and end-of-life care. Doctors in this specialty are often called intensive care physicians, critical care physicians, or intensivists.
An iron lung is a type of negative pressure ventilator (NPV), a 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 muscle control is lost, or the work of breathing exceeds the person's ability. Need for this treatment may result from diseases including polio and botulism and certain poisons.
Airway management includes a set of maneuvers and medical procedures performed to prevent and relieve airway obstruction. This ensures an open pathway for gas exchange between a patient's lungs and the atmosphere. This is accomplished by either clearing a previously obstructed airway; or by preventing airway obstruction in cases such as anaphylaxis, the obtunded patient, or medical sedation. Airway obstruction can be caused by the tongue, foreign objects, the tissues of the airway itself, and bodily fluids such as blood and gastric contents (aspiration).
Respiratory arrest is a serious medical condition caused by apnea or respiratory dysfunction severe enough that it will not sustain the body. Prolonged apnea refers to a patient who has stopped breathing for a long period of time. If the heart muscle contraction is intact, the condition is known as respiratory arrest. An abrupt stop of pulmonary gas exchange lasting for more than five minutes may permanently damage vital organs, especially the brain. Lack of oxygen to the brain causes loss of consciousness. Brain injury is likely if respiratory arrest goes untreated for more than three minutes, and death is almost certain if more than five minutes.
A resuscitator is a device using positive pressure to inflate the lungs of an unconscious person who is not breathing, in order to keep them oxygenated and alive. There are three basic types: a manual version consisting of a mask and a large hand-squeezed plastic bulb using ambient air, or with supplemental oxygen from a high-pressure tank. The second type is the expired air or breath powered resuscitator. The third type is an oxygen powered resuscitator. These are driven by pressurized gas delivered by a regulator, and can either be automatic or manually controlled. The most popular type of gas powered resuscitator are time cycled, volume constant ventilators. In the early days of pre-hospital emergency services, pressure cycled devices like the Pulmotor were popular but yielded less than satisfactory results. Most modern resuscitators are designed to allow the patient to breathe on his own should he recover the ability to do so. All resuscitation devices should be able to deliver more than 85% oxygen when a gas source is available.
Capnography is the monitoring of the concentration or partial pressure of carbon dioxide (CO
2) in the respiratory gases. Its main development has been as a monitoring tool for use during anesthesia and intensive care. It is usually presented as a graph of CO
2 (measured in kilopascals, "kPa" or millimeters of mercury, "mmHg") plotted against time, or, less commonly, but more usefully, expired volume (known as volumetric capnography). The plot may also show the inspired CO
2, which is of interest when rebreathing systems are being used. When the measurement is taken at the end of a breath (exhaling), it is called "end tidal" CO
2 (PETCO2).
A bag valve mask (BVM), sometimes known by the proprietary name Ambu bag or generically as a manual resuscitator or "self-inflating bag", is a hand-held device commonly used to provide positive pressure ventilation to patients who are not breathing or not breathing adequately. The device is a required part of resuscitation kits for trained professionals in out-of-hospital settings (such as ambulance crews) and is also frequently used in hospitals as part of standard equipment found on a crash cart, in emergency rooms or other critical care settings. Underscoring the frequency and prominence of BVM use in the United States, the American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiac Care recommend that "all healthcare providers should be familiar with the use of the bag-mask device." Manual resuscitators are also used within the hospital for temporary ventilation of patients dependent on mechanical ventilators when the mechanical ventilator needs to be examined for possible malfunction or when ventilator-dependent patients are transported within the hospital. Two principal types of manual resuscitators exist; one version is self-filling with air, although additional oxygen (O2) can be added but is not necessary for the device to function. The other principal type of manual resuscitator (flow-inflation) is heavily used in non-emergency applications in the operating room to ventilate patients during anesthesia induction and recovery.
The Combitube—also known as the esophageal tracheal airway or esophageal tracheal double-lumen airway—is a blind insertion airway device (BIAD) used in the pre-hospital and emergency setting. It is designed to provide an airway to facilitate the mechanical ventilation of a patient in respiratory distress.
The history of cardiopulmonary resuscitation (CPR) can be traced as far back as the literary works of ancient Egypt. However, it was not until the 18th century that credible reports of cardiopulmonary resuscitation began to appear in the medical literature.
Diaphragm pacing is the rhythmic application of electrical impulses to the diaphragm to provide artificial ventilatory support for respiratory failure or sleep apnea. Historically, this has been accomplished through the electrical stimulation of a phrenic nerve by an implanted receiver/electrode, though today an alternative option of attaching percutaneous wires to the diaphragm exists.
Surgical airway management is the medical procedure ensuring an open airway between a patient’s lungs and the outside world. Surgical methods for airway management rely on making a surgical incision below the glottis in order to achieve direct access to the lower respiratory tract, bypassing the upper respiratory tract. Surgical airway management is often performed as a last resort in cases where orotracheal and nasotracheal intubation are impossible or contraindicated. Surgical airway management is also used when a person will need a mechanical ventilator for a longer period. The surgical creation of a permanent opening in the larynx is referred to as laryngostomy. Surgical airway management is a primary consideration in anaesthesia, emergency medicine and intensive care medicine.
Advanced airway management is the subset of airway management that involves advanced training, skill, and invasiveness. It encompasses various techniques performed to create an open or patent airway – a clear path between a patient's lungs and the outside world.
A negative pressure ventilator (NPV) is a type of mechanical ventilator that stimulates an ill person's breathing by periodically applying negative air pressure to their body to expand and contract the chest cavity.
The Bragg-Paul Pulsator, also known as the Bragg-Paul respirator, was a non-invasive medical ventilator invented by William Henry Bragg and designed by Robert W. Paul in 1933 for patients unable to breathe for themselves due to illness.
Carl Gunnar David Engström was a Swedish physician and innovator. He is the inventor of the first intermittent positive pressure mechanical ventilator that could deliver breaths of controllable volume and frequency and also deliver inhalation anesthetics.
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