This protocol focuses on the evaluation of the GE noninvasive blood pressure parameter in subjects with dysrhythmias and normal sinus rhythm. The study follows the recommendations of the ANSI/AAMI SP10 Standard.

Inclusion Criteria:

• signed informed consent
• a patient who is undergoing a specialized procedure such as a surgical procedure or cardiac catheterization, or during critical care monitoring in which a central arterial catheter is in place to determine systolic, diastolic, and/or mean arterial blood pressure values.
• ability to monitor ECG, NIBP and/or pulse oximetry
• presence of atrial fibrillation, atrial flutter, or normal sinus rhythm

Exclusion Criteria:

• any subject deemed too unstable, at the clinician's discretion, to participate in the study
• any subject with a cardiac or vascular malformation that results in an abnormal waveform inappropriate to be considered a reference standard
• any subject with a cardiac anomaly that would cause a disparity between aortic pressures and the periphery.
• presence of peripheral vascular disease in arms
• inability to perform a minimum of 4 fast flushes (two at the study beginning and two at the study end) on an arterial catheter or line in order to determine a frequency response. The volume of fluid will not exceed a total pre-specified by the Principal Investigator or designee.
• if the baseline arm to arm mean difference is > 10 mmHg, then the differences will be recorded and evaluated by the Principal Investigator for possible subject exclusion from the data analysis.
• subjects who, at the clinician's discretion, could not tolerate approximately 5 to 12, but possibly up to 25 repeated blood pressures on each arm