Continuous noninvasive blood pressure monitoring during thoracic surgery

To evaluate the usefulness of noninvasive blood pressure monitoring during thoracic surgery, blood pressure measurements obtained with the Finapres 2300 (Ohmeda, Boulder, CO) were compared with an intraarterial catheter system in 10 patients undergoing thoracotomy for lobectomy or pneumonectomy. The Finapres measurements were compared with pressure data obtained ipsilaterally from a radial artery catheter-transducer system. The waveforms were recorded using a strip chart recorder; the systolic (SBP) and diastolic blood pressures (DBP) were measured every 20 seconds on the paper trace. Precision and bias were calculated for SBP and DBP for each patient and for the pooled data, with the invasive blood pressure being considered the gold standard. A total of 1,861 measurement pairs were recorded, 938 pairs during one-lung ventilation. The Finapres underestimated SBP during two-lung ventilation, and overestimated SBP during one-lung ventilation. The precision was good and the biases were small, but there were wide individual variations. It is concluded that the Finapres can be useful in estimating the variability and following the trends of radial arterial blood pressure during thoracic surgery, and is an acceptable alternative to invasive blood pressure monitoring.