Spinal Anesthesia and Regional Hemodynamic Parameters

Sympathectomy in the lower extremities after spinal anesthesia (SA) increases arterial blood flow. This increased blood flow can be detected by pulsed-wave Doppler (PWD) of ultrasonography (USG). The aim of this study was to investigate PWD measurements of the posterior tibial artery (PTA) in patients having SA. The hypothesis was that systolic and diastolic flow velocities in the PTA increase after spinal block.

Patients aged 18-65 years, American Society of Anesthesiologists physical statuses I-II, undergoing elective surgery were included in the study. Using USG and PDW modality, vessel diameter, peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (Vmn), S/D (PSV/EDV ratio), pulsatility index (PI), and resistive index (RI) parameters were measured before, at 5th and 10th minutes after SA from the PTA.

The study was completed with 30 patients with a mean age of 52 years (22-65 years). After SA, the spectral waveform changed from triphasic to monophasic. Vessel diameter, PSV, EDV, Vmn, VTI, and AT values measured with PWD increased, while PI, RI, and S/D values decreased significantly (p < .001). There was a significant correlation between all these parameters and the degree of sensory and motor block.

SA causes significant changes in spectral waveform morphology, vessel diameter, and Doppler-derived flow velocity parameters of the PTA. This technique may serve as a supplementary tool for assessing block success in patients with communication limitations, particularly when SA is preferred over general anesthesia.