Health

What is non-invasive ventilation and its types?

People who suffer from respiratory issues like chronic obstructive pulmonary disease (COPD) are administrated with the support of ventilators to help them breathe. Some patients who are in the intensive care unit and cannot manage to inhale and exhale air on their own are also recommended the use of ventilators. Primarily, ventilation is of two types, invasive and non-invasive. For those interested in knowing more about NIV and its usage, information is provided in the following sections. Here you go!

What is NIV?

Non-invasive ventilation (NIV) ensures the delivery of oxygen via a hose and face mask into the patient’s lungs. The process does not require piercing any body part as it does not use an endotracheal airway to deliver air. This mode of treatment is effective and reduces the total number of days one spends on invasive mechanical ventilation. Experts believe NIV to be better than conventional mechanical ventilation as it reduces the effort one has to put into breathing and improves air exchange.

How does NIV work?

NIV creates positive airway pressure. Here, the pressure outside the lungs is more than the pressure inside the lungs. Because of this, the air gets forced into the respiratory system, lessening the effort one has to put into inhaling air. Also, the treatment method ensures that the chest and lungs stay inflated by increasing the functional residual capacity. It is the amount of air left in the lungs after expiration. This is the air that remains in alveoli for gaseous exchange.

When is NIV used?

NIV is an effective method of supporting the breathing process. The intervention helps patients suffering from respiratory failure in cardiogenic pulmonary oedema, chronic obstructive pulmonary disease (COPD), and other respiratory conditions. 

What are the types of NIV?

Primarily non-invasive ventilation types are non-invasive positive pressure ventilation (NIPPV) and negative pressure ventilation (NPV). 

1. NIPPV:

A non-invasive ventilation type, NIPPV ensures oxygen delivery at a constant or variable rate via a face mask through bi-level positive airway pressure or continuous positive airway pressure.

2. CPAP:

A CPAP machine works on NIPPV and provides constant pressure throughout the process of inspiration and expiration. It causes the airway to stay open and reduces the work of breathing. The CPAP device indicated for home use relies on a low flow generator and is typically meant to treat nocturnal sleep apnea patients. But, when the device is used in the hospital environment, it relies on high flow systems to see that the delivered airflow rates are greater than what is being generated by a distressed patient.

Indications:

  • Used when the patient remains hypoxic despite medical intervention.
  • When a person suffers from type 1 respiratory failure.
  • The patient has congestive heart failure.
  • Someone is suffering from obstructive sleep apnea disorder.
  • In case of rib fractures, when treatment is required to stabilize ribs and prevent lung damage.
  • Nasal CPAP is used in the case of infants.
  1.  BiPAP

A type of NIV, BiPAP provides pressure at different rates depending upon inspiration and expiration. The inspiratory positive airway pressure is typically more than the expiratory positive airway pressure (ePAP). Because of this, ventilation is provided through iPAP, whereas ePAP is meant for people who have collapsed alveoli. 

Indications:

  • When the patient suffers from type 2 respiratory failure.
  • Someone is weaning from tracheal intubation.
  • When a patient is suffering from an acidotic exacerbation of the chronic obstructive pulmonary disease.
  • In case when the patient has to put increased work into breathing.
  1.  NPV:

The negative pressure ventilator offers support through a device that encases a thoracic cage like an iron lung. It operates by decreasing the pressure around the thorax and creating subatomic pressure that inflates the chest walls to expand the lungs. Here, exhalation happens with the passive recoiling of the chest wall. Although NPV was a popular treatment method in the first half of the twentieth century during the Apollo epidemic, at present, its usage is limited. NPV has three types as follows:

  • The first version had a tank ventilator known as an iron lung. It was cylindrical and used to encase the patient’s body, leaving only the head visible. A neck collar offered an airtight seal.
  • There was a poncho wrap consisting of an airtight bodysuit. The version had a rigid metal framework covered by an airtight nylon parker, which surrounded the trunk.
  • The last version consisted of a rigid fibreglass shell that could fit over the chest wall and upper abdomen.

Contraindications of NIV

Some reasons why you should not opt for NIV treatment include:

  • Coma
  • Active tuberculosis
  • Respiratory failure
  • Cardiac arrest
  • Blood vomiting
  • Facial fractures
  • Lung abscess
  • Cardiovascular system instability
  • Raised ICP

When are patients unlikely to do well on non-invasive ventilation?

  • If the patient suffers from multiple organ failure
  • When there is an inability to maintain a lip seal
  • In case of inability to protect the airway
  • When there is a case of overt respiratory failure that requires immediate intubation
  • If there is a presence of excessive secretions or pneumonia
  • If he has a severe illness, including extreme acidosis

How can you set up non-invasive ventilation equipment?

Here are some tips for people trying to set up NIV ventilation:

  • Not trying to set up NIV on your own is recommended if you are unfamiliar with the masks, equipment, and circuits.
  • People who do not know how to safely establish the patient on NIV and use the blood gas results should not set up the equipment.
  • NIV is recommended to be used in ICU/HDU environments. So, be aware of the local policy.

Instructions to follow when using NIV

  • When setting up NIV, make sure to introduce the patient to the equipment slowly.
  • Adjust the settings to ensure maximum comfort and see if the patient is at ease in the lying position.
  • Access the performance of the ventilator while taking a daytime nap to optimize gas exchange.
  • Check the mask fits comfortably and that the patient can feel it on the face without the ventilator.
  • Get an overnight study done for monitoring and optimizing gas exchange and comfort.

What are the complications of using NIV?

NIV is an excellent method of providing breathing support to the patient. But, the treatment method also gives rise to certain complications like

  • Facial pressure ulcers
  • Retention of secretions
  • Eye irritation

NIV ventilation is a preferred mode of providing respiratory support to patients who can’t breathe independently. Primarily, non-invasive ventilator types are two, positive pressure ventilation and negative pressure ventilation. While the latter was quite popular earlier but has limited usage in the present times, the prior is a preferred treatment method at present.

 

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