Friday, September 3, 2021

Ventilator Machine

What is Ventilator ?

What is Ventilator

The ventilator is a life support mechanical device that serves to provide breathing assistance for patients whose breathing is disturbed and does not work normally by providing positive air pressure in the lungs through an artificial airway.

The ventilator is a device for exchanging air in the patient's lungs. Used for patients who experience respiratory failure as lung therapy or oxygen therapy by providing a trigger so that the lungs can work normally. Lung therapy is meant in this case is for patients who can not do inspiration and expiration independently and need a tool to trigger the lungs to work normally again.

The Respiratory System

Breathing is the process of inhaling air containing oxygen, then the lungs exchange oxygen with carbon dioxide, then carbon dioxide is expelled along with the rest of the water vapor through the respiratory system.

The main function of the respiratory system is to meet the oxygen needs of body tissues and remove carbon dioxide as a metabolic waste and play a role in maintaining the balance of acids and bases. The respiratory system works through 3 stages, namely ventilation, diffusion, and transportation.

Anatomy of the Respiratory System

Anatomy of the Respiratory System
Consisting of :
  • Nose - The function of the nasal cavity is to heat the air, humidify the air, and filter the air. Inside the nose, there are nasal hairs that are useful for filtering air from the environment before it enters the interior of the respiratory tract
  • Pharynx - Generally, the pharynx is divided into three, namely, the nasal pharynx which is associated with the nasal cavity, the oral pharynx which is associated with the lung cavity, and the laryngeal pharynx which is associated with the epiglottis of the larynx and into the esophagus.
  • The base of the throat (larynx) - The larynx consists of cartilage plates. In the larynx, there is a vocal cord that will vibrate if there is air through it, such as when speaking.
  • Windpipe (trachea) - The trachea is composed of a ring of cartilage located in front of the esophagus and is pipe-shaped.
  • Throat (bronchus) - The bronchi are the parts that connect the lungs to the trachea.
  • Bronchioles - Branching of the bronchi in the human windpipe. The bronchioles branch into tertiary bronchi in bronchi and then become the site of branching of the alveoli. The surface area of ​​the bronchioles determines the amount of oxygen that can be effectively carried by the lungs.
  • Lungs - The lungs are located in the chest cavity above the diaphragm. The left lung consists of two lobes while the right lung consists of 3 lobes. The lungs are covered by the lining of the lungs. There are 2 layers of the lung membranes and between them consists of a fluid that is useful for protecting the lungs from friction as they expand and deflate.
  • Alveoli - The alveolus is the final channel of the respiratory apparatus in the form of air bubbles. The bubbles are covered with blood capillaries. Alveoli are thin-walled, moist sacs in the lungs that contain air and are tightly attached to blood capillaries, through which gas exchange occurs. The alveolus consists of a single layer of squamous epithelial cells and it is here that the blood is almost directly in contact with the air. The squamous epithelium that lines the alveoli allows the blood in the blood capillaries to bind oxygen from the air in the alveolus cavity. The existence of the alveolus allows the expansion of the surface area which plays an important role in the exchange of O2 gas from the free air to the blood cells and CO2 from the blood cells into the air.
  • Diaphragm - The diaphragm is the muscle that separates the chest cavity from the abdominal cavity, the diaphragm functions to enlarge the available space in the chest cavity to create negative pressure in the chest cavity as a result, it helps increase the suction force of air into the lungs.
The human respiratory system can be divided into 3 structural parts, namely the upper airway, middle airway, and lower airway:
  1. Upper Airway  
    The upper respiratory tract consists of the mouth, nose, nasopharynx, oropharynx, retropharyinx, larynx. This channel serves to move (transport) room air from and into the lungs, warm the air, provide humidity, and filter room Room air is inhaled and then enters the lungs (transport function). In the nose, the air is warmed to match the human body temperature (36.5°C - 37°C) to facilitate the exchange of oxygen or carbon dioxide in the lungs. The air is then humidified as it passes through the nasopharynx. It is the mucous membrane that functions to humidify the air to prevent harm from sensitive tissues. Furthermore, the air will also be filtered from dust particles that are contaminated in the air and will be trapped in the mucous membrane channel for the next time.  
  2. Middle Airway 
    Middle Airway Respiratory
    This airway consists of the trachea, main-stem bronchi, and bronchioles. This channel serves to drain air from the upper respiratory tract into the lungs. In addition, this flow also functions to filter the air from very small dust particles that are not filtered in the upper respiratory tract. Cilia are lined by a mucous membrane that acts as a trap for these tiny dust particles. Cilia are controlled by muscles to push contaminated mucus into the trachea. Contaminated mucus injures the tracheal wall resulting in coughing. Coughing brings contaminated mucus to the surface thereby clearing the respiratory tract.
  3. Lower Airway 
    Lower Airway Respiratory
    The lungs are divided into 2 lobbies, namely the right lung consists of 3 lobbies, and the left lung consists of 2 lobbies. The deep airways consist of the alveolar ducts, alveoli, and pulmonary vascular bed. The respiratory tract is where the exchange of oxygen and carbon dioxide takes place. This channel is also the place where blood and room air meet. In the lungs, precisely in the alveoli, carbon dioxide, which is a waste gas, will diffuse with fresh air that is rich in oxygen.                                                                                                                             

Mechanism for Breathing

In general, human respiration is divided into two phases, namely the inspiratory phase and the expiratory phase. The inspiratory phase is the phase when air enters the lung cavity, starting with muscle contractions between the ribs making the chest cavity lift and the lungs expanding, resulting in the pressure in the chest cavity being smaller than the air pressure outside the chest cavity. so that the air outside the chest cavity containing oxygen can enter the lungs.

The expiratory phase is the phase that occurs after inspiration. Air containing oxygen will enter the lungs will be exchanged with air containing carbon dioxide in the alveoli in the lungs. And then there is relaxation or the return of the muscles between the ribs to their original position accompanied by the fall of the ribs resulting in a small chest cavity. This makes the pressure inside the chest cavity greater than the pressure outside the chest cavity so that air containing carbon dioxide with water vapor can come out.

Mechanism for Breathing
Information :
  • Tidal volume is the volume of air inspired and expired in normal respiration
  • IRV (inspiratory reserve volume) is the volume of air that the lungs can still inhale after a normal inspiration.
  • ERV (expiratory reserve volume) is the volume of air that can still be exhaled after a normal expiration.
  • While the RV (residual volume) is the volume of air that remains in the lungs after a strong expiration.

The lungs have the capacity of respiratory air so that by observing the chart of the human respiratory air volume there is a distribution of respiratory air capacity, among others, tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume.

How Do Ventilators Work

The ventilator works on the principle of oxygenation and ventilation. Oxygenation is the process of distributing oxygen to meet the oxygen needs of the patient so that oxygen can be received and absorbed by the blood to be distributed throughout the patient's body. Then ventilation is the process of getting air in and out of the lungs and out of the lungs so that the process of inspiration and expiration is carried out.
How Do Ventilator Work
The picture above shows how air is delivered. Gas supply is gas that has a higher pressure generally above 1 Bar because the air pressure in open space at conditions above sea level and not in highland conditions, the value is around 1 Bar. The difference in air pressure is intended so that air can flow out of the gas supply through the hose.

Furthermore, in the picture, there is a hand that is likened to a valve whose point is to open or close the air path. In the hand drawing a is likened to an inspiration valve and hand b is an expiratory valve. When the inspiration valve is open (the hand opens the air passage), then the air from the gas supply will be able to flow towards the “Y” piece branching (the part circled in the picture) is like a breathing circuit. If the expiratory valve is also open when the inspiratory valve is open, more air will flow out than enter the balloon which is likened to the lungs. Then the work of the inspiratory valve must be opposite to the work of the expiratory valve, where if the inspiratory valve is open then the expiratory valve must be closed. With the opening of the inspiration valve and the closing of the expiratory valve, there will be a process of distributing air into the lungs, which is called the inspiration process, then by expanding the balloon (which is likened to the lungs), it is hoped that the air needs of the lungs have been met, then the inspiration valve will close and the expiratory valve opens, then the air in the balloon (which is likened to a lung) will flow out of the hose through the expiratory valve, so there is an expiration process. By doing this process repeatedly, the respiratory system will occur.

Ventilator Setting

The ventilator works with a cycle setting. The cycle set is the air supply cycle. The cycle settings are divided into 4 types, namely:
  • Volume Cycle - If the setting used is the volume cycle, then the user will adjust the tidal volume value to be achieved and given to the patient during the air administration process so that the inspiratory flow cycle volume from the ventilator will stop when the set tidal volume is reached.
  • Pressure Cycle - For setting the cycle using a pressure cycle, the user will adjust the inspiratory pressure to be achieved during the oxygen delivery process, so that if the inspiratory pressure has been reached, the ventilator will give a fast time to maintain the inspiratory pressure for air delivery.
  • Time Cycle - Furthermore, when setting using a time cycle, where the time of giving air will be set by the user and the expiration time will follow changes in the setting with reference to the IE ratio. By setting the time cycle, the volume of air received by the patient is adjusted by the length of inspiration time and airflow per minute.

  • Flow Cycle - When setting using a flow cycle, the user will adjust the flow of air to the patient. Giving air to the patient will follow the value of the inspiratory flow set by the user. Furthermore, if the inspiratory flow set by the user is reached, the ventilator will stop delivering air to the patient and replace it with the patient's expiration process.

Ventilator In-Patient

The ventilator is intended for patients with indications:
  • Ventilation problems.
  • Respiratory muscle dysfunction (fatigue, chest wall disturbances)
  • Neuromuscular disease.
  • Decreased ventilatory drive.
  • Obstruction increases resistance to the airway.
  • Impaired oxygenation and recurrent hypoxemia
  • Intensive Care Unit (ICU) patients whose breathing ability is weak mostly use a ventilator that can help supply oxygen, to train the lungs of patients whose condition has improved to be able to breathe without the help of tools and to guard if at any time the patient stops breathing so that the tool can directly replace the respiratory function.