Monday, August 4, 2008

What is CPAP and BIPAP?

Seen here is a nasal mask strapped to a patient's face.  
So you've been told you'd benefit from using a BiPAP or CPAP. This post is my humble attempt at explaining these machines and how they can both save your life in a crisis, and improve the quality of your life long term.

First of all we need some definitions:

CPAP:  This is continuous positive airway pressure.  It's a pressure when you exhale that helps keep your air passages open so that the next breath comes in easier.  Sometimes this is all that's needed to help you get a good nights sleep so that you feel better the next day.

BiPAP:  BiLevel (or Biphasic) Positive Airway Pressure.  It provides a combination of IPAP and EPAP.  This term is generally considered a registered name, although it is usually used as a generic term.  The other term for this is NIPPV.

Seen here is a full face mask.
NIPPV:  Noninvasive Positive Pressure Ventilation.  It's the same as BiPAP.

IPAP:  It's Inspiratory Positive Airway Pressure.  It's a boost of pressure that helps you take in a comfortable sized breath.  It helps improve your ventilation and decrease your work of breathing (it can make your breathing easier).  This is generally applied to help with ventilation.  It is generally applied to help blow off carbon dioxide (CO2), although it can also help you improve oxygenation.

EPAP:  It's the same as CPAP just under a different name.  I  believe it's called EPAP just so that when caregivers are referring to it they know you are talking about CPAP given with IPAP.

Ventilation:  IPAP helps with ventilation.  It makes sure you take in a deep enough breath to inhale enough air or oxygen, and to exhale enough CO2.  It is determined by your rate and depth of breathing.

Rate:  On both CPAP and BiPAP machines the patient determines the rate (although a minimal setting may be dialed into newer models)

Seen here is the mouth-nose mask.
Depth:  In CPAP the patient controls the depth of each inspiration.  On BiPAP the IPAP helps to control the depth of each inspiration.

Carbon dioxide (CO2):  It is the waste product of cellular metabolism inside your body.  If your ventilations are not adequate, it will build inside your body, thus making you sick.  IPAP can help improve ventilation and help you blow off enough CO2 so you continue to feel good.

Oxygen:  It is the product inside the air you need to stay alive.  If your air passages collapse, perhaps while you are relaxed, sedated, or sleeping, you may have a difficult time getting in a breath.  This often causes you to wake up several times during the night.  CPAP or EPAP helps keep your air passages open so the next breath comes in easier.  Sometimes this is all that is needed (usually only at night) to help you live a normal, functioning life during the day.

This is the type of machine used in the hospital
setting.  This machine is called a Vision, and
can be used to supply both CPAP and BiPAP.
It looks more complex than home machines,
although it basically does the same thing; it just
comes with more bells and whistles.
Oxygenation:  The level of oxygen inside your body.  It's the measure of the amount of oxygen inside your body.  Medical care givers have little devices that can help determine your oxygenation level.  Both IPAP and EPAP can help improve oxygenation.

Sleep study: A study to determine if you have a problem ventilating while you are sleeping, and to test to see what machine (BiPAP or CPAP), and what settings, remedies the problem.

Home health care provider: They usually provide the equipment you use at home.  They make sure you understand the equipment, and help you find a mask that works great for you.  When your equipment needs servicing, these are the people you will deal with.

Respiratory Therapist:  These are the caregivers who manage this equipment in the hospital settings.  If you come into the hospital suffering from shortness of breath, they may work under the direction of a doctor to set you up on a CPAP or BiPAP machine.  Usually he sets up the machine short term for one of several reasons.  If your doctor feels you need continued use of the machines for home use, he can help you qualify and refer you to a home care provider.

This is an example of a home BiPAP machine.
They are generally quiet, and come with a built
in humidifier for comfort.  
The modern machines are generally small enough to sit on your bedside table.  The newer ones are so quiet that no one else in the room, nor yourself, will hear it.  Connected to the machine is wide bore tubing which is connected to a mask.  In the hospital we have one size fits all masks, although at home you can try an array of different ones until you fine one that works great for you.

There are a variety of situations that would cause you to require the aid of such devices. Some of which include:

Sleep Apnea: Your airways collapse when you are in a deep sleep, and therefore you stop breathing.  This causes you to be very tired the next day. This is diagnosed during a sleep study, and the remedy is CPAP while sleeping.

  1. Chronic Obstructive Lung Disease (COPD): A disease process prevents you from taking in an adequate breath to take in oxygen and blow of carbon dioxide.  The result is your COPD gets worse.  BiPAP may remedy this situation by making sure you get a 
  2. Heart Failure (CHF):  This is a disease process whereby your heart isn't working effectively, and fluid backs up in your lungs, thus making it hard to breath.  Pressure from a BiPAP machine will help decrease the amount of blood returning to the heart, thereby decreasing the work of heart.  The machines will also help you take in a deep enough breath to improve ventilation, and keep your lungs open to improve oxygenation.  The machine, when used for this reason, is only temporary. It essentially improves work of breathing until the physician figures out what's wrong with you and fixes the problem.  
  3. Other:  
    This is the Respironics 460, a newer version of the Vision.
    It's ideal for the hospital setting.  The mask shown here is
    generally the type we use in the hospital settings.  
    There are definitely other reasons for these machines, of which I will not delve into in this post. Although I have seen these machines improve work of breathing during the short term for asthmatics during severe exacerbations, and I've seen them work nice long term for pulmonary fibrosis patients long term.  
I assure you that if your doctor or caregiver recommends that you try one, then you need it.  By working with your caregiver, be it a respiratory therapist, sleep study specialist, home care provider, or physician, the experience should be a good one for you.  By being compliant, such machines may help improve your present medical condition, and improve the quality of your life long term. 

Note:  This post was originally published 8/4/08 and rewritten 9/18/13


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Jackie Stenner said...

Thx so much for this very clear and well-written post!

My 2.5 year old was just put on bipap for cchs. The information here totally answered my questions regarding the intricacies of bipap ventilation.

Anonymous said...

Normally I wouldn’t comment on posts but I felt that I had to as your writing style is really good. You have broken down a difficult area so that it easy to understand.

smscott said...

wonderful post, very informative. I only wish I had found it earlier, my mom was on BiPap in the hospital for the last 48 hrs or so before she died and I had no real clue what it was

Rick Frea said...

That's why I think it's important to have medical professionals who anticipate patient and patient family questions and explain what's going on and what the equipment is for.

Anonymous said...

Very helpful, thank you.

tomcruse said...

Really a great post regarding cpap and Bipap. It is very informative and also useful for those who are suffering from problem like sleep apnea. Thanks for sharing such a nice post...

Jess Toons said...

My dad has problems breathing at night were you will hear him breathing then nothing then its like he can't breath and then he'll start up again. Its a scary thing to watch. I have heard about bipap machines Minnesota that he could possibly try out. I would love to get one for him to try. Thanks for explaining more what they are exactly, it's helped out a lot.

people2007 said...

Epap is the same as delta pressure?

hair by Darcy-Niccole said...

As a fellow RT, I am a new graduate going through orientation at my first hospital. They said changing modalities based off ABG interpretation was my biggest weakness this was very helpful anything else would be appreciated