By Diane Huberty, Retired RN, Certified Neuro Nurse
...and ALS Patient
Is it NIV, Bi-Level, BiPAP, AVAP or a Ventilator?
Any machine used to move air into the lungs is a ventilator. Some measure each breath given by the pressure,
others by the volume, so a ventilator can be categorized as a pressure or a volume ventilator. That means diddly to
an ALS patient having trouble breathing. What we care about is whether the air is delivered with a mask or requires
a tube inserted into the airway. That categorizes ventilators into Non-Invasive Ventilation (NIV) with a mask, and
Invasive Ventilation through an airway tube. Invasive ventilators don't have an abbreviation because for many years
they were the only ventilators. They are commonly referred to simply as a vent.
The first NIV machine was the Iron Lung which used negative air pressure to lift the rib cage and draw air in.
The Iron Lung isn't used today but there are vest sized machines that still use negative pressure.
NIV machines using Positive Airway Pressure (PAP) were developed in the 1980s to help people with sleep apnea, a
condition where the airway collapses during sleep causing the person to stop breathing repeatedly. By pushing air
directly into the lungs through a mask worn over the nose, the machine keeps the airway inflated so it won't
collapse. This is CPAP, Continuous Positive Airway Pressure. It is not the correct NIV for people with ALS because
the constant pressure makes it difficult to exhale when abdominal muscles are weak. The result is a feeling of
suffocation which is no improvement over not being able to inhale without the machine! If your doctor is
recommending a CPAP machine, it is definitely time to see a Pulmonologist familiar with ALS.
In the 1990s computer technology added a new
dimension to NIV. Now the machine could push air in until a preset pressure was reached, then reduce the pressure to
allow the person to exhale easily. Repeating this cycle made breathing more comfortable and suitable for people with
neuromuscular diseases who could not exhale against the higher pressure. This type of machine was sold by
Respironics using the brand name BiPAP (Bi-Level Positive Airway Pressure). Like the patented brand names "Kleenex"
and "Band-Aide", BiPAP has become the common name for all such products even though there are other brands of
A typical Bi-Level machine's settings are limited to
Spontaneous which only assists breaths initiated by the user.
Timed triggers the user to take breaths a preset number of times a minutes.
S/T combines the settings to allow the user to breathe at their own rate but triggers extra breaths as needed
to assure a minimum number of breaths per minute. S/T is the correct setting for ALS patients.
Bi-Level machines continue to become more advanced and make important changes in respiratory care. Like CPAP,
Bi-Level machines were developed for home use but are increasingly used in Emergency Departments, during procedures,
and even in Intensive Care. Computer technology has added the ability to store details of use in newer machines
which can help in adjusting settings for optimal use. This information can be brought up on the machine's viewer or
using an SD memory card. Another change to newer Bi-Level machines is that nearly all now have alarms to alert
caregivers to problems in delivering air. A change that is slowly coming is the addition of an internal battery.
Without an internal battery, the machine has to plugged in or be connected to an external battery to run. The use of
external lithium battery packs has made them more portable than lugging around a car battery sized battery. A few
Bi-Levels do have an internal battery that can power it for up to 5 hours.
The newest innovation in NIV is AVAP (Average Volume Assured Pressure Support) In the past, Bi-Level machines
relied entirely on pressure to deliver the amount of air per breath. Volume monitoring was previously only available
on Vents. AVAPS continuously detects the volume of air in each breath, averages it, and adjusts the amount of
pressure gradually to assure the patient receives the right volume of air. Because the changes are adjusted whenever
needed and are gradually applied, they aren't noticed by the user. Air leaks are adjusted for as well as changing
masks and altitude changes. Like some other Bi-Levels, it can be set to gradually ramp up to its settings when you
first put it on. All of this adds up to significantly more comfort as well as better control of CO2 levels.
There are several critical distinctions
between NIV and an Invasive Ventilator:
NIV requires only a mask, mouthpiece, or nasal plugs which can put on or taken off as needed.
Invasive ventilation requires either an endotracheal tube placed through the mouth or nose and down past the
vocal cords to the trachea. This is an emergency measure. If it becomes apparent that the patient will need
invasive ventilation for a prolonged time, a tracheostomy will be done to open a hole in the neck to place a
tracheostomy tube directly into the trachea. A trach tube is far, far more comfortable than an endotracheal tube!
For those who have decided to have a tracheostomy when Bi-Level ventilation becomes insufficient, that alone is
good reason to do the tracheostomy before it is an emergency situation.
NIV is not considered "Life Support Equipment." An Invasive Ventilator can be set to completely take over
breathing. Bi-Levels can only assist breathing. The progression of ALS continues to weaken the muscles needed to
breathe. A person on NIV will need to increase the hours per day of NIV use. NIV will reach the limit of its
ability to sustain oxygenation and therefore life, so when 24-hour use is necessary, the decision on whether to
change to invasive ventilation will need to be made.
An Invasive Ventilator has more options in settings, including delivering higher pressures than Bi-Levels are
designed to give. This makes it more effective and often necessary in severe pneumonia or blood clots in the
Because NIV only pushes air in until the set pressure is reached, it won't deliver enough air when the lungs
are filling up with congestion. It will reach the set pressure faster and switch to exhale, leaving you dangerously
under-oxygenated, struggling for more air, and exhausting your breathing muscles. A trip to the ER and facing
whether to go on invasive ventilation with a trach is next.
ALS patients often reach the point of not being able to cough effectively. If a Cough Assist machine isn't
effective and suctioning is needed by patients using NIV, the tube has to be passed through the nose or mouth.With
invasive ventilation, secretions can be removed by passing a suction tube through the trach tube to remove
The presence of the tracheostomy tube increases the risk of lung infections because it bypasses some normal
protective barriers. Use of NIV also creates increased risk for lung infections and sinus infections as well as
pressure sores from the mask or nasal pillows and the discomfort of air filling the stomach.
A growing trend is to use a hybrid ventilator such as the Trilogy which can be set for Bi-Level ventilation
with a mask or mouth held tube, or for use with invasive ventilation. This option makes the transition to invasive
ventilation easier if it becomes necessary. Medicare has ruled that if you use a Trilogy or other invasive
ventilator for non-invasive ventilation, your co-pay will be higher than it would be for a Bi-Level machine.
One final comparison between NIV and invasive ventilation is the warning that a invasively ventilated person
requires 24/7 care. That is true and yet misleading.
How many people who are on Bi-Level ventilation during the day, whether part time or full time, are safe at
home alone anyway? Arm weakness is usually a big part of the picture at this point so putting on or adjusting the
headgear requires assistance as does using a cough assist. Power outages, equipment malfunction, toileting,
choking, mosquito attacks, fire, etc. all require assistance 24/7 regardless of the type of respiratory equipment
The care required can be provided by anyone given ten minutes of instruction on how to suction and the
opportunity to practice doing so. A little info on how to troubleshoot a beeping vent and using an ambu bag and
they are all set. No licensed nursing care needed.
The caregiver doesn't need to be in the room or even in the house. As long as they are close enough to get back
in a minute or two and a reliable method for the PALS to summon them has been set up, they can have the freedom to
spend the afternoon outside or at a neighbor's watching football.
HomeVentGuide.pdf is an excellent resource on all
the types of ventilation devices. It shows those available in different parts of the world and the settings, size,
weight, power source, and alarms on each type and brand.