BiPAP: (IPAP, EPAP), Principle, Operation, Pros, Cons, Handling

BiPAP stands for Bilevel Positive Airway Pressure. It is a type of non-invasive positive pressure ventilation. Unlike the CPAP machine, it provides two levels of air pressure to the patient. In comparison to the CPAP machine, the BiPAP machine will also have the feature of the CPAP. Besides that, it may also have the features of the APAP. Hence, in terms of features, it is better to buy the BiPAP machines rather than buying a CPAP. Here, we will be talking about the working mechanism, settings, operation procedures, pros, cons, handling, and the list of authorized dealers for you to purchase the machine in Kathmandu, Nepal.

Levels of pressure

  • Inspiratory Positive Airway Pressure (IPAP):- It is the pressure that is applied during inspiration. The set value for IPAP generally ranges from 10 to 20 cm H2O.
  • Expiratory Positive Airway Pressure (EPAP):- It is the pressure that is applied during expiration. The set value for EPAP generally ranges from 5 to 12 cm H2O.

(Inspiration is an active process that needs more energy than expiration. Similarly, expiration is a passive process that does not need much energy. Thus IPAP is always greater than EPAP.)

BiPAP Setting

1. Modes of BiPAP

  • CPAP mode:- Provides a single continuous airway pressure during inspiration and expiration.
  • APAP mode:- APAP stands for Auto CPAP. It is an advanced version of the CPAP mode. Here, the machine will automatically set and change the CPAP pressure based on the requirement of the patient.
  • S mode: Spontaneous mode in which the patient controls the breathing cycle.
  • T mode: Timed mode in which the alteration between IPAP and EPAP is based on the set time.
  • S/T mode: It is a combination of both the spontaneous and timed mode. If the patient is unable to breathe spontaneously within the set time, the timed mode will work. Else, the spontaneous mode will operate.

2. Parameters

Different models of the machine allow the users to set different parameters. Some, of the major ones, are as follows:

  • EPAPmin = 4 cm H2O
  • IPAPmax = 20 cm H2O
  • PSmin = 3 cm H2O
  • PSmax = 15 cm H2O

(Note:- Even though there are multiple parameters in the machine, you really do not need to alter those values for most of the cases. The general parameters that you need to worry about is the IPAP and the EPAP pressure.)

The machine can also have the following features.

  • Inspiratory to Expiratory  (I: E) Ratio
  • Actual Breathing Rate
  • Estimated Tidal Volume, Minute Volume, and Air Leakage
  • No. of Apneas
  • Alarm button, alarm reset, etc.

Difference between CPAP and BiPAP


Stands for Continuous Positive Airway Pressure Stands for Bilevel Positive Airway Pressure
It continuously provides a single airway pressure to the patient. However, the set value can be changed as per the requirement of the patient. It continuously provides two airway pressures to the patient. One is during the inspiration, while the other one is during expiration.
CPAP is useful for the treatment of patients with normal breathing problems such as sleep apnea. If the condition of the patient becomes much more complex, then BiPAP is better.
Since a single high positive pressure is applied continuously, expiration might be difficult. Since a lower airway pressure is applied during expiration, breathing becomes much easier.
It is cheaper to purchase It is much more expensive in comparison to the CPAP.

BiPAP Mask

Mainly, two types of BiPAP masks are in use.

These masks are also used in CPAP machines.

How does BiPAP work?

Block Diagram of CPAP, BiPAP
Image Source:


Atmospheric air goes to the blower of the machine through the filters. The blower compresses the air and sends high-pressure air to the connecting tube. Then the air goes to the patient through the nasal mask.

The pressure sensor senses the air pressure in the connecting tube. This sensed pressure goes to the microprocessor. Then the microprocessor analyzes the variation among the set and obtained pressure value. In case of any variation, it either increases or decreases the voltage signal of the driver motor. This, in turn, controls the speed of the blower. Based on the companies there can be some variations in the above block diagram.

Breathing Cycle Under BiPAP

Inspiration increases the volume of the lungs. This causes a sudden drop in intra-alveolar pressure. On sensing this drop of pressure, the machine applies pressure equal to IPAP. The pressure gradient (IPAP> intra-alveolar pressure) causes air to flow from the machine to the lungs. At the end of the inspiration, intra-alveolar pressure becomes equal to IPAP.

The expiration might be triggered by the drop in the air inflow to the threshold value. On, detecting the decreased air inflow, EPAP is applied by the machine. The expiration causes a fall in the intra-alveolar pressure. Once the pressure lowers below EPAP value, IPAP pressure activates again for the next breathing cycle.


 Pressure Support (PS) ≈ IPAP – EPAP


  • Connect the AC cord to the machine and the power supply
  • Connect connecting tube, mask, and humidification tank (if needed)
  • Turn on the machine
  • Pre-heat the water of the humidifier before use (30 mins earlier)
  • Set the parameters in your setting option. The values will be prescribed by your doctor.


  • Continuous high airflow might cause patients, difficult sleep
  • High air pressure might cause patients, difficult to expire
  • Chance of air leakage from the BiPAP masks
  • Dry nose and mouth
  • Headache to some patients


  • Use soap water to clean mask and humidification tank
  • Do not use alcohol to clean the machine. You can use Collins.
  • Always use distilled water in the humidification tank
  • An ultra-fine filter is disposable
  • The film filter is washable (life span: 6 months)
  • Check for any leakage in the tubing system.

You may not be able to manually wash the tubing, mask, and humidification tank properly. Thus in that case you can use a CPAP Cleaner to get the job done.

BiPAP Suppliers in Nepal

Numerous suppliers are available in Kathamandu, that deal with this machine. Some of them are as follows.

They are some of the authorized dealers of the BiPAP machines available in Kathmandu, Nepal. You may ask them for the brochures, services, technical supports, and the price of the machine.



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