Mechanical ventilation

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Mechanical Ventilation is a medical term for artificial ventilation in which mechanical devices are used to assist or replace spontaneous breathing. This may involve a machine called a ventilator or respirator that may be assisted by an anesthesiologist, registered nurse anesthesiologist, physician, physician assistant, respiratory therapist, paramedic, EMT, or other suitable person compressing a bag or set of bellows. Mechanical ventilation is called "invasive" if it involves instruments that penetrate the trachea through the mouth, such as endotracheal tubes or skin, such as a tracheostomy tube. There are two main types: positive pressure ventilation, where air (or other gas mixture) is pushed into the trachea, and negative pressure ventilation, where air, in essence, is sucked into the lungs. There are many modes of mechanical ventilation, and their nomenclature has been revised for decades as technology continues to develop.

Video Mechanical ventilation

Usage

Mechanical ventilation is indicated when the patient's spontaneous ventilation is insufficient to maintain life. This is also indicated as prophylaxis for the collapse of other physiological functions, or ineffective gas exchange in the lungs. Since mechanical ventilation only serves to provide breathing aid and does not cure the disease, the condition underlying the patient should be irreversible and should be resolved over time. In addition, other factors must be considered because mechanical ventilation is not without its complications

In general, mechanical ventilation is instituted to improve blood gases and reduce respiratory work.

Common medical indications for use include:

• Acute lung injury (including ARDS, trauma)
• Apnea with respiratory attacks, including cases of intoxication
• Severe acute asthma, requiring intubation
• Acute on chronic respiratory acidosis most commonly with chronic obstructive pulmonary disease (COPD) and obesity hypoventilation syndrome
• Acute respiratory acidosis with partial pressure of carbon dioxide (p CO
  ₂ ) & gt; 50 mmHg and pH & lt; 7.25, which may be due to diaphragmatic paralysis due to Guillain-Barrà © Ã… © syndrome, myasthenia gravis, motor neurone disease, spinal cord injury, or the effects of anesthetic and muscle relaxants
• Increased respiratory work evidenced by significant tachypnea, retraction, and other physical signs of respiratory distress
• Hypoxemia with partial pressure of arterial oxygen and ( Pa O
  ₂ ) & lt; 55 mm Hg with an additional fraction of oxygen inspiration ( Fi O
  ₂ ) = 1.0
• Hypotension includes sepsis, shock, congestive heart failure
• Neurological diseases such as muscular dystrophy and amyotrophic lateral sclerosis

Maps Mechanical ventilation

Related risks

Barotrauma - Pulmonary barotrauma is a well-known positive mechanical stress mechanical complication. These include pneumothorax, subcutaneous emphysema, pneumomediastinum, and pneumoperitoneum.

ventilator-related lung injury - Ventilator-related lung injury (VALI) refers to acute lung injury that occurs during mechanical ventilation. Clinically indistinguishable from acute lung injury or acute respiratory distress syndrome (ALI/ARDS).

Diaphragm - Controlled mechanical ventilation can cause a rapid type of unused atrophy involving diaphragmic muscle fibers, which may develop within the first day of mechanical ventilation. The cause of atrophy in the diaphragm is also a cause of atrophy in all respiratory muscles during controlled mechanical ventilation.

Motility of mucosilia in the respiratory tract - Positive pressure ventilation seems to damage the motility of the mucociliary in the respiratory tract. Bronchial mucus transport is often impaired and associated with retention of secretions and pneumonia.

Complications

Mechanical ventilation is often a life-saving intervention, but it carries potential complications including pneumothorax, airway injury, alveolar damage, and ventilator-related pneumonia. Other complications include diaphragm atrophy, decreased cardiac output, and oxygen toxicity. One of the main complications that arise in patients with mechanical ventilation is acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). ALI/ARDS is recognized as a significant contributor to patient morbidity and mortality.

In many health care systems, long ventilation as part of intensive care is limited resources (because there are only so many patients who can receive treatment at any given moment). It is used to support a single organ system that fails (lungs) and can not reverse the underlying disease process (such as terminal cancer). For this reason, there can be (sometimes difficult) decisions to be made about whether it is suitable to start someone with mechanical ventilation. Much of the ethical issues surrounding the decision to stop mechanical ventilation.

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Apps and duration

These can be used as short-term measures, for example during surgery or critical illness (often in intensive care unit settings). It can be used at home or in a nursing home or rehabilitation institution if the patient has a chronic illness requiring long-term ventilation assistance. Because of the human pharynx, larynx, and esophageal anatomy and the circumstances in which ventilation is necessary, additional measures are often necessary to secure the airway during positive pressure ventilation to allow uninterrupted air passage into the trachea and avoid air. passing into the esophagus and stomach. The common method is to insert a tube into the trachea: intubation, which provides a clear route for air. It may be an endotracheal tube, inserted through the oral or natural nostril, or tracheostomy inserted through an artificial opening in the neck. In other circumstances, simple airway maneuvers, oropharyngeal breath or laryngeal breath mask can be used. If the patient is able to protect his own airway and non-invasive ventilation or negative pressure ventilation is used then an airway enhancer may not be necessary.

Negative pressure engine

The iron lung, also known as the Drinker and Shaw tanks, was developed in 1929 and was one of the first negative pressure machines used for long-term ventilation. It was refined and used in the 20th century mainly as a result of the polio epidemic that swept the world in the 1940s. This machine is, in effect, a large elongated tank, which wraps the patient up to the neck. The neck is sealed with a rubber gasket so that the patient's face (and airways) are exposed to the air of the room.

While the exchange of oxygen and carbon dioxide between the bloodstream and the air space of the lungs works by diffusion and requires no external work, air must be moved to and out of the lungs to make it available for gas exchange processes. In spontaneous breathing, negative pressure is created in the pleural space by the respiratory muscles, and the gradient produced between atmospheric pressure and pressure within the thorax results in airflow.

In an iron lung using a pump, the air is mechanically pulled to produce a vacuum inside the tank, thus creating a negative pressure. This negative pressure causes chest expansion, which causes decreases in intrapulmonary pressure, and increases ambient airflow to the lungs. When the vacuum is released, the pressure inside the tank equates ambient pressure, and the elastic coil of the chest and lungs causes passive respiration. However, when the vacuum is made, the stomach also expands along with the lungs, cutting the venous flow back into the heart, leading to the collection of venous blood in the lower limb. There is a large peephole for access to nurses or home assistants. The patients can talk and eat normally, and can see the world through a series of well-placed mirrors. Some can remain in this iron lung for years at a fairly successful time.

Currently, mechanical ventilator negative pressure is still used, especially with polio hospital in England such as St. Thomas Hospital in London and John Radcliffe in Oxford. The leading device used is a smaller device known as a steel coating. The steel layer is a shell-like unit, creating a negative pressure only to the chest using a combination of a fitting shell and a soft gall bladder. Its primary use is in patients with neuromuscular disorders that have some of the remaining muscle function. However, it tends to fall and causes severe blisters and skin damage and is not used as a long-term tool. In recent years this device has reappeared as a modern polycarbonate shell with a double seal and a high-pressure oscillation pump to perform biphasic cuirass ventilation.

Positive pressure

The design of a modern positive pressure ventilator is based primarily on technical developments by the military during World War II to supply oxygen to fighter pilots at high altitudes. The ventilators replace iron lungs as safe endotracheal tubes with high volume/low pressure cuffs developed. The popularity of positive pressure ventilators increased during the polio epidemic in 1950 in Scandinavia and the United States and was the beginning of modern ventilation therapy. Positive pressure through a manual supply of 50% oxygen through a tracheostomy tube causes a decrease in mortality rates among patients with polio and respiratory paralysis. However, due to the large amount of manpower required for such manual intervention, positive pressure mechanical ventilators are becoming increasingly popular.

The positive pressure ventilator works by increasing the patient's airway pressure through an endotracheal tube or tracheostomy. Positive pressure allows air to flow into the airway until ventilator breathing is stopped. Then, the airway pressure drops to zero, and the elastic elasticity of the chest wall and lungs pushes the tidal volume - the breath out through passive breathing.

Transway pressure

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• P _TA = Transway pressure
• P _AO = Pressure on airway opening
• P _ALV = Pressure on alveoli

Intermittent ventilator abdominal pressure

Another type is intermittent ventilator abdominal pressure that applies external pressure through the pumped bladder, forcing breathing, sometimes called exclusiveness. The first apparatus was Bragg-Paul Pulsator. The name of one such tool, Pneumobelt made by Puritan Bennett should be a common title for its kind.

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Type of ventilator

Ventilators come in a variety of styles and methods of giving a breath to sustain life. There are manual ventilators such as a bag valve mask and anesthesia pouch which requires the user to hold the ventilator to the face or to the artificial airway and keep the breath with their hands. Mechanical ventilators are ventilators that require no operator effort and are usually controlled by a computer or pneumatic.

Mechanical Ventilator

Mechanical ventilators typically require power by the battery or wall socket (DC or AC) even though some ventilators work on non-power-consuming pneumatic systems.

• Transportation Ventilator - This ventilator is small and rougher, and can be pneumatically activated or via AC or DC power source.
• Intensive care Ventilator - The ventilator is larger and typically runs on AC power (although almost all contain batteries to facilitate intra-facility transport and as a backup in case of electrical problems). This ventilator style often provides greater control over various ventilation parameters (such as inspiration time). Many ICU ventilators also incorporate graphics to provide visual feedback from every breath.
• Neonatal Ventilator - Designed with premature neonates in mind, this is a special part of the ICU ventilator designed to provide the smaller, more precise volume and pressure required to ventilate this patient./li>
• Positive respiratory pressure ventilator ( PAP ) - This ventilator is specifically designed for non-invasive ventilation. These include ventilators for home use for the treatment of chronic conditions such as sleep apnea or COPD.

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Delivery breathing

Trigger

It is these triggers that cause breathing to be delivered by mechanical ventilators. Breathing can be triggered by patients taking their own breath, ventilator operators pressing the manual breath button, or by the ventilator based on the regulated breathing rate and ventilation mode.

Cycle

This cycle causes the breath to transition from the inspiration phase to the respiratory phase. Breathing can be recycled by a mechanical ventilator when the set time has been reached, or when the preset flow or maximum flow percentage delivered during the breath is achieved depending on the type of breath and its arrangement. Breath can also be cycled when an alarm condition such as a high pressure limit has been reached, which is the main strategy in controlled regulated pressure volumes.

Restrict

The limit is how the breath is controlled. Breath may be limited to a set of maximum circuit pressures or a set of maximum flow.

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Breath breath

Inhalation in mechanical ventilation is almost always completely passive. The ventilator expiration valve is open, and expiratory flow is allowed until baseline pressure (PEEP) is reached. Expiratory flow is determined by patient factors such as adherence and resistance.

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Dead Space

The mechanically dead chamber is defined as the volume of the exhaled gas as a result of its use in mechanical devices.

Example calculations for mechanical dead spaces

${\ displaystyle V_ {Dmech} = V_ {T} -V_ {Dphys} - {\ frac {PaCO2 (V_ {T} -V_ {D} -V_ {Dmech} )} {P_ {ACO_ {2}}}}}  ÂÂ$

Versi Sederhana

${\ displaystyle {\ frac {V_ {D}} {V_ {T}}} = {\ frac {PaCO_ {2} -P {\ bar {E}} CO_ {2}} {PaCO_ {2}}}}  ÂÂ$

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Mode ventilasi

Mechanical ventilation uses several separate systems for ventilation called modes. Fashion comes in many different delivery concepts but all modes fall into one of three categories; volume-cycled, pressure-cycled, spontaneously cycled. In general, the selection of mechanical ventilation modes used for certain patients is based on the physician's familiarity with the mode and availability of equipment at a particular institution.

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Modify settings

In adults when 100% Oxygen (O2) (1,00 Fi O
₂ ) used initially, easy to calculate Fi O
₂ for use and easy to estimate shunt fraction. The shunt fraction is thought to refer to the amount of oxygen that is not absorbed into the circulation. In normal physiology, gas exchange (oxygen/carbon dioxide) occurs at the level of the alveoli in the lungs. The existence of shunt refers to any process that inhibits the exchange of this gas, causing the oxygenated oxygen to be inspired and the oxygenless flow of blood back to the left heart (which ultimately supplies the rest of the body with non-oxygenated blood).

When using 100% O2 ( Fi O
₂ 1.00), the shunting rate is estimated by reducing the size Pa O
₂ (from arterial blood gases) of 700 mmHg. For each 100 mmHg difference, the shunt is 5%. A shunt of more than 25% should immediately look for the cause of this hypoxemia, such as major trunk intubation or pneumothorax, and should be treated accordingly. If such complications do not exist, other causes should be sought, and a positive end-expiratory pressure (PEEP) should be used to treat intrapulmonary shunt. Other causes such as shunt include:

• Alveolar collapse from major atelectasis
• Alveolar collects materials other than gases, such as pus from pneumonia, water and proteins from acute respiratory distress syndrome, water from congestive heart failure, or blood from hemorrhage

Weaning from mechanical ventilation

The withdrawal time from mechanical ventilation - also known as weaning - should be considered carefully. Patients should have ventilation considered for withdrawal if they can support their own ventilation and oxygenation, and this should be assessed continuously. There are some objective parameters to look for when considering withdrawals, but no generalized criteria are generalizations for all patients.

The Rapid Shallow Breathing Index (RSBI, the ratio of respiratory frequency to tidal volume (f/VT), formerly referred to as "Tobin Index" after Dr. Martin Tobin of Loyola University Medical Center) is one of the most studied and the best. commonly used weaning weeds, without other predictors that have been shown to be superior. It was described in a prospective cohort study of mechanically ventilated patients who found that RSBI & gt; 105 breaths/min/L is associated with weaning failure, while RSBI & lt; 105 breaths/min/L are predicted to wean success with sensitivity, specificity, positive predictive value and negative predictive value of 97%, 64%, 78%, 95% respectively.

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Respiratory monitoring

One of the main reasons why a patient is treated in ICU is for mechanical ventilation delivery. Patient monitoring in mechanical ventilation has many clinical applications: Increases understanding of pathophysiology, assistance with diagnosis, guides patient management, avoids complications and trends assessment.

In a ventilated patient, pulse oximetry is commonly used during FIO2 titration. Reliable Spo2 target is greater than 95%.

Different strategies exist to find PEEP levels in patients with ARDS guided by esophageal pressure, Stress Index, static air volume pressure curve. In such patients, some experts recommend limiting PEEP to low levels (~ 10cmH2O). In patients with reduced hydration, PEEP may be used as long as it does not cause plateau pressure to rise above the upper inflection point.

Most modern ventilators have basic monitoring tools. There are also monitors that work independently of the ventilator that allows to measure the patient after the ventilator is removed, such as the T test tube.

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Artificial airway as a connection to ventilator

There are various procedures and mechanical devices that provide protection against airway collapse, air leakage, and aspiration:

• Facial mask - In resuscitation and for small procedures under anesthesia, the facial mask is often sufficient to reach the seal against air leakage. The airway patency of the unconscious patient is maintained either by jaw manipulation or by using nasopharyngeal or oropharyngeal airway. It is designed to deliver the air passage to the pharynx through the nose or mouth, respectively. Badly installed masks often cause bridge nose ulcers, a problem for some patients. Face masks are also used for non-invasive ventilation in conscious patients. However, full face masks do not provide protection against aspiration.
• tracheal intubation is often performed for mechanical ventilation from hour to week duration. A tube is inserted through the nasal (nasotracheal intubation) or mouth (orotracheal intubation) and continues into the trachea. In most cases, tubes with blowing cuffs are used for protection against leakage and aspiration. Intubation with cuffed tubes is considered to provide the best protection against aspiration. The tracheal tube definitely causes pain and cough. Therefore, unless the patient is unconscious or anesthetized for other reasons, sedatives are usually given to provide tube tolerance. Other disadvantages of tracheal intubation include damage to the nasopharyngeal or oropharyngeal mucous layer and subglottic stenosis.
• Supraglottic airway - supraglottic airway (SGA) is any breathing device that sits above and beyond the trachea, as an alternative to endotracheal intubation. Most devices work through masks or cuffs that expand to isolate the trachea for oxygen delivery. The newer device displays an esophageal port for suctioning or a port for tube exchange to allow intubation. The supraglotic breath differs mainly from tracheal intubation because it does not prevent aspiration. After the introduction of the laryngeal mask airway (LMA) in 1998, supraglottic airway devices have become mainstream in elective and emergency anesthesia. There are many types of SGA available including Esophageal-tracheal Combitube (ETC), Laryngeal tube (LT), and obsolete Esophageal obstructionator (EOA).
• Cricothyrotomy - Patients requiring emergency airway management, where tracheal intubation is unsuccessful, may require airways inserted through surgical opening in the cricothyroid membrane. This is similar to tracheostomy but cricothyrotomy is provided for emergency access.
• Tracheostomy - When the patient requires mechanical ventilation for several weeks, the tracheostomy can provide the most appropriate access to the trachea. Tracheostomy is a pathway that is made surgically into the trachea. The tracheostomy tube is well tolerated and often does not require the use of tranquilizers. The tracheostomy tube may be inserted early during treatment in patients with severe pre-existing respiratory disease, or in any patient expected to be difficult to wean from mechanical ventilation, ie patients with little muscle reserve.
• Spokesman - A less common interface, does not provide protection against aspirations. There is a lipase spokesperson with flanges to help withstand it if the patient is unable.

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Ventilation formula

Greek physician Galen may first describe mechanical ventilation: "If you take a dead animal and blow air through its larynx (through the reeds), you will fill the bronchus and see the lungs reach the greatest distension." Vesalius also describes ventilation by inserting a reed or cane into an animal trachea. In 1908 George Poe demonstrated his mechanical respirator by acidifying dogs and apparently bringing them back to life.

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See also

• Biotrauma
• Charles Hederer, inventor of pulmoventilateur
• Medical Ventilator

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References

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External links

• e-Medicine, an article on mechanical ventilation along with technical information.
• International Ventilator User Network (IVUN), Information source for home mechanical ventilation users.

Source of the article : Wikipedia