Bilevel Therapy

Bilevel therapy works by delivering two different levels of positive air pressure: a higher level of pressure when you inhale and a lower level of pressure when you exhale. There are a number of conditions for which a physician might prescribe bilevel therapy.

Bilevel devices can provide therapy for people with obstructive sleep apnea (OSA) if they have found continuous positive airway pressure (CPAP) therapy too difficult. Bilevel devices can also provide noninvasive positive pressure ventilation (NPPV) for people with respiratory disorders or other forms of sleep-disordered breathing (SDB).

While bilevel and CPAP therapy are both forms of positive airway pressure, bilevel therapy differs from CPAP in a couple of significant ways: first, bilevel devices deliver "assisted breaths," not continuous pressure, so they fall into the category of ventilation; second, physicians prescribe bilevel therapy for many types of SDB whereas physicians usually prescribe CPAP for OSA.

Some bilevel devices have a back-up rate, which means that the machine can provide extra breaths as necessary for those patients who require it. These types of devices are not used for OSA but for patients with central sleep apnea or respiratory insufficiency.

Conditions Frequently Treated with Bilevel Therapy
Because bilevel therapy performs so well in supporting ventilation and reversing high carbon dioxide, it has enjoyed a rapid expansion in use. Now, physicians typically use bilevel therapy to treat a broad range of conditions, including the following:

nocturnal hypoventilation
respiratory insufficiency
neuromuscular disease
respiratory failure
chest wall deformity
chronic obstructive pulmonary disease (COPD)
ALS or Lou Gehrig's disease
obstructive sleep apnea (OSA)

Bilevel therapy is not typically prescribed for OSA patients; however, OSA patients who require high treatment pressures or have another respiratory condition are often candidates for bilevel therapy.