CONTINUOUS, ONLINE, REAL-TIME SPECTRAL-ANALYSIS OF SAP SIGNALS DURINGCARDIOPULMONARY BYPASS

We communicated the application of continuous, on-line, real-time powe r spectral analysis of systemic arterial pressure (SAP) signals during cardiopulmonary bypass when the heart was functionally but reversibly disconnected from the blood vessels. Based on observations from 15 ca ses of successfully completed coronary artery bypass grafting procedur es, we found that the very low (0.00-0.08 Hz), low (0.08-0.15 Hz)-, hi gh (0.15-0.25 Hz)-, and very high (0.80-1.60 Hz) frequency components of SAP signals exhibited differential changes before, during, and afte r cardiopulmonary bypass. In particular, the very low-frequency compon ent, which purportedly represents the contribution of vasomotor activi ty to SAP, presented only a mild decrease in power during hypothermic cardioplegia. Interestingly, the total peripheral resistance also mani fested only a slight reduction during the same period. On the other ha nd, the low-, high-, and very high frequency components were essential ly eliminated. These results unveiled an active role for the blood ves sels in the maintenance of SAP during cardiopulmonary bypass, possibly as a result of a maintained vasomotor tone as reflected by the sustai ned very low frequency component of the SAP signals.