Mechanical Ventilation : modes of ventilation and complications

 Mechanical ventilation : Mechanical ventilation is the process of using a machine to assist a patient with breathing. This is often necessary in situations where a patient is unable to breathe on their own, such as in cases of respiratory failure or after major surgery. Mechanical ventilation involves the use of a ventilator machine, which delivers oxygen to the patient's lungs and removes carbon dioxide.

The process of mechanical ventilation involves several important steps

The first step is to insert an endotracheal tube or tracheostomy tube into the patient's airway. This allows the ventilator to deliver oxygen directly to the lungs. The ventilator then delivers a set amount of air to the patient's lungs, based on their specific needs. The rate and volume of air delivered by the ventilator can be adjusted to meet the patient's changing needs.

When mechanical ventilation performed ?

When GCS ( Glasgow coma scale) less then 8 

Hb less then 7 

RR ( respiratory rate ) more then 50 

Parameters of mechanical ventilation 

1 )Respiratory rate 

In mechanical ventilators the respiratory rate is denoted by ( Flow ) 

12-16 breath /minute is normal value of Breathing.

ETco2 ( End tidal Co2 normal value is 35-45 if it increases from 45-55 then we increase respiratory rate from 16-18 to wash out the carbon dioxide from our body and this phenomenon we called Hyperventilation .

2)VT 

In medical term we write TV As VT ( Tv mean tidal volume) Average value is (7 )

We take it on the basis of hight .

We have person his/her hight is 70inch .

We have formula 

Person hight =70inch

1st 60 inch is = 50 kg it is constant 

Remaining  10 will be multiply with 2.3 and this 2.3 will be constant (10x2.3=23+50=73) it means that her/his age is 73 , Now we will multiply 73 with VT (73x7=511Vt tidal volume, 

We will provide 511 VT to 73 years old person 

3) Hight is Decrease From 60 ( Formula) 

For M (male) hight in cm - 152.4 x0.9+50

For F=hight in cm -152.4x0.9+45

Point to be noted that Any problems which occur in RR we will treat with ideal weight .

And the complications which occur with drugs we will consider original weight. 

4) PEEP (Positive End expiratory pressure )

It is a technique used in mechanical ventilation . Where small amount of pressure applied to the airway at the end of exhalation.

Normal value in adults is = 5cmH20 PEEP

In Child = 4cmH20 PEEP

if PEEP is maximum 10-12 it will no complications . And if increasing from 10-12 will cause Barrow Trauma 

Complications of Mechanical ventilation

Mechanical ventilation can be a life-saving procedure, but it is not without risks. Complications can include pneumonia, lung injury, and respiratory muscle weakness. Patients who require mechanical ventilation may also experience discomfort and anxiety, and the use of sedatives may be necessary to help them remain calm and comfortable.

Modes of ventilation

1. Volume-Controlled Ventilation (VCV):

   In this mode, the ventilator delivers a set volume of air to the patient's lungs with each breath. The ventilator delivers a preset tidal volume at a set respiratory rate, with inspiratory and expiratory times that can be adjusted. VCV is often used for patients who require controlled ventilation, such as those with acute respiratory distress syndrome (ARDS).

2. Pressure-Controlled Ventilation (PCV):

   In PCV, the ventilator delivers a set pressure of air to the patient's lungs with each breath. The tidal volume varies based on the patient's lung compliance and resistance. The respiratory rate and inspiratory and expiratory times can be adjusted. PCV is often used for patients who have variable lung compliance, such as those with chronic obstructive pulmonary disease (COPD).

3. Pressure Support Ventilation (PSV):

   In PSV, the ventilator delivers a set pressure of air to support the patient's spontaneous breathing efforts. The patient initiates each breath, and the ventilator delivers additional pressure to make it easier for the patient to breathe. The tidal volume varies based on the patient's lung compliance and resistance. PSV is often used for patients who are weaning from mechanical ventilation.

4. Continuous Positive Airway Pressure (CPAP):

   In CPAP, the ventilator delivers a continuous positive pressure to the patient's airway during both inspiration and expiration. The pressure helps to keep the airway open and improve oxygenation. CPAP is often used for patients with sleep apnea or acute respiratory failure.

5. Bi-level Positive Airway Pressure (BiPAP):

   In BiPAP, the ventilator delivers two different levels of positive pressure: a higher level during inspiration and a lower level during expiration. BiPAP can help to improve ventilation and oxygenation while reducing the work of breathing. BiPAP is often used for patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF).