The Changes of Differences of Pulse Transit Time between Toe and Finger in General and Epidural Anesthesia

Abstract

Background: Pulse wave velocity (PWV) and pulse transit time (PTT) are influenced by the arterial wall stiffness and compliance. Also, the PTT is dependent on blood pressure changes that can be accompanied by the anesthesia. The simply measured PTT has difficult to discriminate the arterial compliance changes from blood pressure changes. Therefore, we investigated that the differences of PTT between toe and finger as an independent parameter on blood pressure. Methods: Eighteen patients scheduled for elective lower abdominal gynecologic surgery were studied. General anesthesia was achieved with sevoflurane and epidural block was done with 0.2% ropivacaine and fentanyl 100μg via epidural catheter inserted into L1－L2 epidural space. PTT was measured in a finger (PTTf) and a toe (PTTt) by the time difference between the ECG R wave and the pulse wave of PPG. Blood pressure and PTT was measured at three instances such as preinduction (Pre), 5 minutes after intubation (Int5) and 30 minutes after injection of epidural dose (Epi). The time delay of PTT between toe and finger (PTTt-f) was measured. Results: PTTf and PTTt was prolonged at Int5 and Epi. But the PTTt-f was not different between the Int5 and Epi because of prolonged PTTf caused by the blood pressure decrement after the epidural block. Conclusions: PTTf, PTTt and PTTt-f can be a one of the convenient measurement of the arterial compliance but it was suggested that there need to be a parameter less dependent on the blood pressure changes. (Korean J Anesthesiol 2007; 53: 21～6)