The purpose of this study is to establish the accuracy of the non-invasive Mespere Oximeter that estimates venous oxygen saturation.

The conventional pulse oximeter has been a standard in clinical care for non-invasive hemodynamic monitoring, which only measures arterial blood oxygenation. The clinical application of venous oximetry is numerous, including severe sepsis and septic shock, severe trauma and hemorrhagic shock, and heart failure and cardiac arrest.

The existing method for venous blood oxygenation monitored is either through an invasive fiber optic catheter, or intermittently by blood sampling and CO-Oximetry. However, catheterization can be costly and can include inherent risks. Therefore, due to the inherent risks of catheterization, venous oximetry is limited only to critically ill patients.

By non-invasively monitoring venous blood oxygenation, the Mespere Oximeter provides more complete information on patient hemodynamics.

Inclusion Criteria:

• Age 18 and older
• Heart failure patients already receiving RHC as part of their usual care
• Signed written and informed consent

Exclusion Criteria:

• Lack of patient consent
• Subject is pregnant
• Evidence of abnormal neck anatomy
• Subject does not have visible left and right jugular veins
• Subject has occluded internal jugular veins under ultrasound imaging
• Allergic to adhesive tape
• Ongoing photodynamic therapy
• Presence of known anatomical shunt or AV dialysis fistula
• Known central vein stenosis

Acute and chronic heart failure patients already receiving right heart catheterization (RHC) as part of their usual care