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 person's airway. By pushing air into the
lungs through a mask worn over the nose, NIV assists breathing. This technology was 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 in, the machine keeps the airway inflated so it won't collapse.
This is CPAP, Continuous Positive Airway Pressure.
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 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. 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 however.
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 preset 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 whether to go on a full vent and trach
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 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 part time 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 malfunction, 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 watching football.