Anecdotally there appears to be a difference between the 'expected' and actual INR when a POC device is used. Concern exists that patients may be inappropriately denied the potential benefits of central neural blockade (CNB) if a POC device provides a falsely high result, or conversely the investigators may be proceeding with CNB in patients with an unacceptably high INR if POC provides a falsely low result. There is also the possibility of improving hospital efficiency using this device as it provides a result much faster than the laboratory.