The purpose of the present study was to evaluate the feasibility of blood pressure (BP) estimation by means of pulse arrival time (PAT) from data records of ICU patients available at the MIMIC public database. Datasets consisting of ECG, PPG and arterial BP waveforms from 8 subjects were used for the analysis and the relationship of PAT with systolic, diastolic and mean blood pressure was assessed through a linear regression fit. The analysis was carried out on datasets of short (20 min) and long (60 min) duration in order to evaluate the temporal changes on the linear relationship. The results showed high correlation between BP and PAT for both the short-term and the long-term analyses. The mean absolute error found between the true and estimated systolic BP values was close to 5mmHg; however, the error noticeably increased on the long-term dataset for all subjects.