Acute Congestive Heart Failure

1. Males and females, ages 18-75
2. Able and willing to provide written informed consent or not able to give informed consent because of mechanical respiration
3. Diagnosis of acute or chronic decompensated heart failure with pulmonary congestion or edema
4. Systolic blood pressure >80 mm Hg at time of enrollment
5. Resting pulse oximetry (SpO2) at the time of enrollment of at least 88% at 21% iron oxides (FeO2)
6. Agreement to be measured with the study devices according to study protocol by patient or legal representative
7. Left ventricular ejection fraction (LVEF) \< 40% in 3D- Echocardiography

Exclusion Criteria:

1. Active participation in another interventional research study
2. Surgery of the upper airway, nose, sinus or middle ear within the last 90 days
3. Major medical or psychiatric condition that would interfere with the demands of the study or the ability to complete the study. For example, severe unstable chronic lung disease such as obstructive (FEV1/FVC ≤ 30%), or restrictive (FVC \< 50% predicted) lung disease, neuromuscular disease, cancer, or renal failure
4. Unable to use PAP therapies due to physical issues (e.g. facial structural abnormalities) or cognitive issues (e.g. dementia)
5. Participants in whom positive airway pressure (PAP) therapy is medically contraindicated.
6. Uncontrolled hypertension (systolic ≥200 mm Hg/diastolic ≥120 mm Hg)
7. Pregnancy
8. Lactation
9. Implanted pacemaker / Cardiac Resynchronization Therapy (CRT) / implantable cardioverter-defibrillator (ICD) except for Medtronic devices with Opti Vol Algorithm
10. Incompetent patients or patients who, in the judgment of the investigator, are too unstable or are otherwise not capable of performing study procedures
11. Post-partum cardiomyopathy
12. Hypertrophic
13. Primary mitral valve stenosis
14. Patients requiring more than 50% supplemental oxygen or patients requiring more than 4 lpm oxygen
15. Patients with persistent ventricular arrhythmias (Premature ventricular coupling, periods of ventricular tachycardia)
16. Patients chronically classified (prior to admission) as New York Heart Association (NYHA) Class IV or American Heart Association Class D heart failure
17. Patients with glomerular filtration rate (GFR) \<30 or obligatory dialysis
18. Resting respiratory rate >30 breaths per minute
19. Patients requiring mechanical ventilation or patients with an artificial airway (endotracheal or tracheostomy tube)
20. Patients with carbon monoxide toxicity
21. Patients with severe sepsis (defined as also an organ dysfunction due to an infection according to the Guidelines of the German Association of Sepsis, February 2010)