This article is incomplete.
Bi-level ventilators, also known by the trade name BiPAP®, are non-invasive ventilators that alternate between a high and low pressure to facilitate breathing.
Bi-level ventilators are capable of facilitating respiration in an individual that has almost zero ability to breathe on their own. However, in the case of ALS, spasticity (stiffness) of the diaphragm muscle may prevent sufficient respiration from occurring, even with the use of a bi-level machine that is configured to provide a great deal of support.
Bi-level ventilators are not strictly considered to be life-saving devices, however, it is possible for the user to be so dependent upon its function that they could lose their life if it were to fail or if they were to lose access to it.
Many different bi-level ventilators exist in the market. Some have special features built into them, such as cough assistance.
Bi-level ventilators work in a number of different ways, depending on the model. ALS patients will typically use a standard ventilator, or, an automatic ventilator.
A standard bi-level ventilator is programmed by a qualified individual to provide a specific level of ventilation. Configurable parameters include: a high-level pressure, a low-level pressure, delay between breaths, and the steepness of the ramp transitioning between high and low pressure levels. These parameters are not intended to be user-configurable.
An automatic bi-level ventilator is similar to a standard model, but adapts its own parameters based on how the individual is breathing. A model of this type may be used for a short time, when the level of assistance needed by the individual is low, and to potentially inform the physician about what parameters should be used in a standard ventilator.
Automatic ventilators are a little easier to get used to, and can make the transition to a standard ventilator more comfortable.
Ventilators have data acquisition functionality. Some may be connected to a wireless modem that is used to automatically upload the data to qualified personnel for evaluation. Otherwise, data can be read from a removable storage device in the unit.
The feeling of a ventilator can be challenging to adjust to. It is best to use it during the daytime at first, to get used to the feeling. Nighttime usage requires adapting to the feeling of the ventilation itself, along with the feeling of the mask, and the sound that the machine makes.
Discontinue use of the ventilator if it causes pain, or if it is still intolerable after many attempts to get acclimated to it. Contact a qualified individual to make configuration changes to the machine.
Breathing difficulties are encountered progressively, similar to limb weakness. Early usage of a bi-level ventilator typically begins with occasional usage when breathing difficulties are being encountered. Often, these difficulties are most pronounced when lying down. As a result, overnight use tends to be the most common time when the ventilator first gets consistent use.
Usage of the ventilator will increase as breathing difficulties worsen. Daytime use on an as-needed basis typically follows a period of only using it overnight. Eventually, the ventilator may be needed constantly except for brief periods such as speaking, when consuming food, or maintaining oral hygiene.
🚧
🚧
The ventilator should be within reach of the user whenever possible.
The ventilator should always be placed at an elevation that is slightly lower than the user's head. The water reservoir in the machine may leak in some circumstances; having the user's head slightly higher reduces the risk of ingesting water through the vent tube.
The hose that connects the mask to the machine should be free of twists or kinks, and should be easy to move. It should be possible for the user to lie on either their right side or left side in bed, without the hose being under any tension. Leakage at the mask may occur if the hose becomes taught when lying in a certain position; in extreme circumstances, the mask may come right off.
Bi-level ventilators are fitted with heated water humidifiers to increase comfort for the user. Distilled water is recommended, however, clean municipal water may be used temporarily.
Water that is not distilled may cause boiler scale (calcium deposits) to form inside the reservoir.
Avoid overfilling the water reservoir. An overfilled reservoir can cause water to travel through the air hose. Turn off the machine and decrease the water level if bubbling sounds are heard.
All parts of the ventilator between the water reservoir, and the mask should be cleaned daily to prevent buildup of bacteria. The water reservoir, despite being very far away from the users mouth is susceptible to accumulating significant amounts of bacteria.
The water reservoir, hose, and mask should be replaced every 🚧.
🚧
Bi-level ventilators are designed to tolerate a modest amount of leakage in the hose and at the mask fitment interface. Achieving a perfect seal is not possible. However, excessive leakage will negatively affect operation. The ventilator will compensate for leakage by increasing the flow volume; this may produce a feeling of having one's face in a strong breeze. Breathing is uncomfortable in this circumstance and can be challenging. If the leak is extreme, inadequate flow of air into the lungs will result, and the machine will trigger an alarm.
Leakage is usually easy to hear and feel; checking for leaks and attempting to mitigate them is prudent, especially before going to the trouble of having the ventilator's settings changed.
Leakage may occur anywhere there is pressurized air between the ventilator outlet and the user's face. This includes:
Leakage at the mask interface can often be reduced by adjusting the headgear. Replacing the mask may be necessary if adjustment doesn’t resolve the issue. Over time, the mask gasket can wear out, preventing a proper seal. A different size mask may be required if replacement alone doesn’t fix the problem.
🚧
Dry or damaged skin can occur at the mask interface, or around the mouth. Use of a suitable moisturizer may work in some cases.
A ventilator whose water reservoir, hose, and mask are not regularly cleaned significantly increases the risk of infection due to the buildup of bacteria. The ventilator equipment should be cleaned daily to minimize this risk.
Eye infection can be caused by significant leakage at the mask interface in the direction of the eyes. Eye infection can be prevented by keeping the equipment extremely clean, and adjusting the mask fitment interface to prevent leaks.
A bi-level ventilator can generate sufficient pressure to force air past the esophageal sphincter, leading it into the stomach and eventually the intestines. This air is then released as flatulence.
Essentially, the pressurized air from the ventilator will follow the path of least resistance. If there are restrictions or blockages in the nasal cavity or other parts of the airway, the air will divert into the digestive system instead.
Speaking while wearing a mask is difficult. The listener may not be able to understand what is being said, unless it is being said loudly between in-breaths from the machine.
Products exist which amplify the speaker's voice through the mask so that they can be more easily understood.
The user may be able to temporarily remove the mask to speak if they are able. An alarm will be triggered if the mask is left off for a prolonged length of time, and the machine is still running.
Bi-level ventilators are often not available for sale to the general public; a ventilator must be prescribed by physician.
Unlicensed assistive personnel or other caregivers may require training before being allowed to even touch a ventilator.
Spare parts for ventilators, such as replacement masks, hoses, and water reservoirs may be hard to come by in some regions. It is wise to have a spare set of all of these items in case of accidental loss or breakage.