Accuracy of Oximeters With Hypoxia and Methemoglobin or Carboxyhemoglobin

The conventional pulse oximeter has been a standard in clinical care for non-invasive hemodynamic monitoring, which only measures the arterial blood oxygenation. There are many clinical situations where tissue hypoxia may exist despite normal values obtained by conventional pulse oximeter. This can be cause by inadequate monitoring of oxygen demand (i.e. venous oxygen saturation) of the tissues.

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 those critically ill patients. 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.

More complete information on patient hemodynamics can be provided by non-invasively monitoring of venous blood oxygenation.

Inclusion criteria

• Healthy volunteers between the ages of 21 and 49 years of either gender

Exclusion criteria

• smokers
• pregnancy
• any chronic medical condition including heart disease, hypertension, pulmonary disease, liver or kidney disease
• obesity
• evidence of abnormal neck vein anatomy