BiPAP is a non-invasive ventilatory assist machine. Non-invasive ventilation (NIV) machines
are those that can help breathing without requiring a tube inserted into the persons airway. By
pushing air into the lungs through a mask worn over the nose, NIV assists breathing. This
technology was developed in the 1980's to help people with sleep apnea, a condition where the
airway collapses during sleep causing the person to stop breathing repeatedly. By pushing air
in, the machine keeps the airway "inflated" so it won't collapse. This is CPAP, Continuous
Positive Airway Pressure.
In the 1990's 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
brand name "Kleenex", BiPAP has become the common name for all such products.
BiPAP is a ventilatory assist machine, but it is not a full featured traditional ventilator.
A ventilator can do everything BiPAP does but a BiPAP can't do all the things a ventilator can.
There are several critical distinctions between BiPAP and a traditional ventilator:
BiPAP is "non-invasive", requiring only a mask that can put on or taken off as needed. The
acronym "NIV" (Non-Invasive Ventilation) is used to differentiate traditional, trached
ventilation from CPAP and BiPAP. A traditional ventilator is "invasive" meaning it requires
that a tube be put down your throat or through your neck (tracheotomy) into the lungs. The tube
remains in place as long as the patient needs to use the ventilator even if they reach a point
where they can be off the ventilator for hours at a time. A growing trend is to use a hybrid
ventilator such as the Trilogy which can be set for bilevel ventilation with a mask or mouth
held tube, giving the non-invasive benefits of BiPAP, or for use with a trach and vent. This
option makes the transition to trach ventilation easier if it becomes necessary. Getting
insurance coverage for an expensive vent to be used for BiPAP is likely to be difficult
BiPAP is not generally considered "Life Support Equipment." A ventilator can be set to
completely take over breathing, BiPAP can only assist the breathing.
A ventilator is generally set to deliver air according to volume. It pumps air in until a
certain volume has been reached, then releases it. BiPAP delivers air according to pressure,
stopping when it senses resistance that tells it that the pre-set amount of pressure has been
met. That is a technical difference that probably means very little in how it feels to be
on a ventilator versus BiPAP. It may however affect how well lung function is maintained. A
volume based air delivery will continue to inflate lungs fully and help prevent atelectasis
(loss of the ability of the little air sacs at the furthest reaches of the lungs to expand) and
pneumonia. A pressure based delivery system will sense resistance and not try to push air into
stiff or clogged air sacs and therefore won't be as helpful in keeping them working.
BiPAP cannot support breathing adequately as ALS progresses. When breathing becomes very
shallow, BiPAP doesn't have the sensors to recognize this nor the built in ability to
compensate by increasing pressure. A ventilator will sense this and alarm. A ventilator can
deliver higher pressures than BiPAP is designed to give.
Because BiPAP 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 the question of whether to go on
a full vent and trach is next.
Ventilator patients can be fitted with trach tubes that allow them to eat and even to
speak, but occasionally this is not possible for ALS patients. Because it does not require a
trach, BiPAP does not interfere with any speech or swallowing they can still do.
ALS patients often reach the point of not being able to cough effectively. With a
ventilator and trach, secretions can be removed by passing a suction tube through the trach to
remove secretions. If suctioning is needed by patients using BiPAP, the tube has to be passed
through the nose or mouth.
The presence of the trach increases the risk of lung infections because it bypasses some of
the normal protective barriers. Use of BiPAP also creates some increased risk for lung
infections and sinus infections.
One final comparison between Bilevel respiratory support is the warning that a ventilated
person requires 24/7 care. That is true and yet misleading.
How many people who are on bilevel ventilation during the day, whether parttime or full
time, are safe at home alone anyway? Arm weakness is usually a big part of the picture by this
point so putting on or adjusting the head gear requires assistance as does using a cough
assist. Power outages, equipment malfuntion, toileting, choking, mosquito attacks, fire, etc.
all require assistance 24/7 regardless of the type of respiratory equipment needed.
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 neighbors