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 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 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 watching football.