Both CPAP and Bi-Level therapy are forms of positive airway pressure (PAP) therapy. CPAP therapy delivers one level of pressure when you inhale and exhale. Bi-Level therapy delivers two levels of pressure set to coincide with your inhaled and exhaled breaths. Generally, the inhalation pressure is set higher than the exhalation pressure. Bi-Level therapy can be recommended for sleep apnea clients that have difficulty with CPAP therapy.