COMPARISON OF INVASIVE AND NONINVASIVE MEASUREMENT OF CONTINUOUS ARTERIAL-PRESSURE USING THE FINAPRES IN PATIENTS UNDERGOING SPINAL-ANESTHESIA FOR LOWER SEGMENT CESAREAN-SECTION

We have compared arterial pressures measured by an indwelling radial c annula with those obtained non-invasively by the Finapres 2000 (Ohmeda ) during spinal anaesthesia for lower segment Caesarean section. The d igital outputs of both pressures were recorded using a computerized sy stem. We studied 20 patients, yielding a total of 18772 data points af ter elimination of data recorded during arterial flushing and erroneou s results from each source. The data analysis demonstrated a normal di stribution for differences between the two methods of measurement, and the correlations between invasive and Finapres readings for systolic, diastolic and mean pressures were 0.78, 0.72 and 0.79, respectively, indicating an overall poor reflection of intra-arterial pressure by th e Finapres under these circumstances. Some patients and some periods o f readings reflected a high degree of precision and little bias. Howev er, unexplained large differences in pressure and trends of change tha t were out of phase over time occurred frequently. We conclude that th e Finapres cannot be recommended as a monitor of arterial pressure in this group of patients in whom sudden hypotension may be a threat to m aternal or fetal outcome.