BACKGROUND: Venous regurgitation into the infusion line and subsequent occlusion frequently occurs during blood pressure (BP) measurement. The purpose of this study was to obtain the pattern and the actual range of peripheral venous pressure (PVP) change during NIBP measurement before and during enflurane anesthesia. METHODS: Adult size NIBP cuff was placed on the same arm on which IV infusion set was placed. PVP waveforms during BP measurement were recorded from 6 subjects. PVPs were measured before induction and at 30 min after induction of enflurane anesthesia (n=19). As the PVP waveform during NIBP measurement was biphasic in shape, values of baseline PVP (BEFORE), first peak (PEAK1), notch between two peaks (NOTCH), second peak (PEAK2) were measured. Timed control data were obtained from six volunteers. RESULTS: PEAK2 was always higher than PEAK1. Range of peak PVP was 12-130 mmHg (57.6 2.5 mmHg, mean S.E.) and PVP change was augmented during enflurane anesthesia (p<0.05). Enflurane anesthesia accentuated correlationship between mean arterial pressure and PVP. CONCLUSION: Our observation showed that peak PVP occurred during deflation phase and its range of variation was substantial. Changes in the pattern and the autoregulation of PVP by enflurane needs further investigation.