The MACS is the first line of defense for treating critically ill patients in respiratory failure. The CPAP pressure and additional oxygen relieve shortness of breath, allow the patient to breathe easier, and help reduce their anxiety. Many EMS departments have established mask CPAP protocols for treating cardiac and respiratory emergencies. Patients with congestive heart failure (CHF), asthma, acute respiratory failure (ARF), trauma, COPD, near drowning, or any patient with severe breathing difficulty could benefit from mask CPAP application.