Fourier transform analysis of the blood pressure profiles in transdermal clonidine treated hypertensive patients undergoing abdominal surgery

Twenty-nine hypertensive patients scheduled for minor abdominal surgical procedures and chronically treated with any antihypertensive oral therapy (AOT), underwent a 24-hour noninvasive blood pressure monitoring (ABPM). Fifteen days before the operation, the AOT was substituted with transdermal clonidine (TSC) 0.1 mg./day or 0.2 mg./day. Two days before and two days after the surgical procedure, the ABPM was repeated. The Fourier transform was used for the smoothing of the blood pressure curves. The authors found no statistically significant difference between the AOT profiles and the TSC profiles. As expected, they observed a significant increase in the heart rate in the post surgery ABPM in comparison with the ABPM before the operation. The use of transdermal clonidine is particularly useful in the surgical settings, because it maintains stable blood pressure profiles throughout the perisurgical period and it reduces the need for nursing time.