Collect continuous systolic and diastolic blood pressure values and waveforms as recorded by an arterial line catheter and by non-invasive blood pressure (NIBP) and to collect Photoplethysmogram Pulse Oximetry (PPG) waveform in order to optimize the Sensifree algorithm.

Sensifree is developing a continuous non-invasive blood pressure measurement system, that uses a fingertip PPG sensor as a signal source. The system provides systolic, diastolic and mean arterial pressure values, for use in hospitals and other clinical settings. The PPG waveform is analyzed by a proprietary software algorithm, calculating BP values.

The current best method to obtain similar information is by using an Arterial line catheter which will serve as a reference device. In this study, the sponsor aims to prospectively collect continuous radial arterial line & PPG waveforms, as well as NIBP data over the period of the surgery in order to test and refine the algorithm.

Inclusion Criteria:

1. Signed inform consent
2. Age 18 or greater
3. Elective surgery that requires invasive BP monitoring (A-line)

Exclusion Criteria:

1. Emergency surgery
2. A-line not inserted
3. Informed consent not signed

Patients scheduled for elective surgery involving placement of radial artery A-line for BP monitoring