A technique for comparing pressure oscillations obtained during a blood pressure determination wherein two or more sets of matching criteria may be employed. The set of matching criteria to be employed is determined based on the heart rate variability or the presence of heart beat irregularities or arrhythmias as determined by an independent heart monitor, such as an ECG. The selected set of matching criteria may then be employed in determining the acceptability of the time interval between two oscillations and the equivalence of the two oscillations based upon one or more oscillation characteristics, such as peak amplitude. In this manner, non-consecutive oscillations may be matched and used in determining blood pressure.