BIOMED ARENA    Volume:1, Issue:1, May 2015 

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Helping you breathe   -Technical Article

Types of Ventilators

1)    Volume Ventilators

2)    Pressure Ventilators

3)    High Frequency Ventilators


Ventilator control system

A control system ensures that the ventilator produces the correct breathing pattern.

This requires setting basic controls, including:

    •       Size of the breath

    •       How fast and often the breath is brought in and let out

    •       How much effort, if any, the patient needs to exert to start a breath


A spontaneous breath occurs when the patient can control the timing and size of the breath. This is normally referred as cycled ventilators. These are as follows:

1)    Volume Cycled

2)    Pressure Cycled

3)    Time Cycled


Ventilator Modes

The effort of gas exchange involves a mandatory breath. A particular pattern of spontaneous and mandatory breaths is referred to as a ventilation mode.

Numerous ventilation modes allow ventilators to produce various breathing patterns, to suit the individual needs of the patient. These modes coordinate with ventilator functions.They are as follows :

1)    Volume Modes

2)    Pressure Modes


Further classified as follows:

In Volume

a)    Assist Control (AC)

b)    Synchronized Intermittent Mechanical Ventilation (SIMV)


In Pressure

a)    Pressure Controlled Ventilation (PCV)

b)    Pressure Support Ventilation (PSV)

c)     CPAP / PEEP

d)    BiPAP


Ventilator Settings / Controls

Every Human Being requires different settings depending on his Height, Weight, Sex and other clinical parameters. So settings in Ventilators are the most important parameter. The most common settings are

1)    Tidal Volume

2)    Minute Ventilation

3)    Breath Rate

4)    FiO2

5)    I:E Ratio

6)    Pressure support

7)    Peep


Ventilator monitors


Most positive pressure ventilators have an airway pressure monitor to assess the pressure in the circuit. They have a volume measure to assess the volume of the patients breaths. These also monitor if the patient is properly connected to the ventilator.

Many positive pressure ventilators have sophisticated pressure, volume and flow sensors. These sensors control the ventilator's output and monitor the interaction between the patient and the ventilator. These monitors allow the caregiver to follow the patient's condition in form of Loops & Graphs too.

1)    Patient Monitoring Parameters

a)    Exhaled  Tidal Volume

b)    Delivered FiO2

c)     Patient Breath Rate


2)    Graphs


a)    Pressure VS Volume

b)    Volume VS Flow


3)    Loops


a)    Pressure VS Time

b)    Volume Vs Time

c)     Flow Vs Time




When the patient or Ventilators behave abnormally or if there is any trouble there has to be a indication, and for that, Alarms become the important parameter for the end user to understand the patient and change the settings accordingly. Also if the ventilator malfunctions or if there is any other technical issue alarm system is the indication the end users can understand .The commonly featured alarms are as follows:


1)    High Pressure

2)    Low Pressure

3)    Apnea

4)    Low Oxygen

5)    Service


This was a basic overview towards mechanical ventilation. 

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