Ultrasonographic Carotid Artery Flow Measurements as Predictors of Spinal Anesthesia-Induced Hypotension in Elderly Patients: A Prospective Observational Study

Abstract

BACKGROUND In elderly patients, spinal anesthesia-induced hypotension (SAH) can be frequently caused by reduced preload and stiff ventricles. The primary purpose of this study was to investigate the ability of ultrasonographic carotid artery flow measurements during the passive leg raise (PLR) test to predict SAH in elderly patients. The correlation between preoperative transthoracic echocardiography (TTE) measurements and SAH was also investigated. MATERIAL AND METHODS The patients aged over 65 years scheduled for elective surgery under spinal anesthesia were recruited. Preoperative TTE was performed in all patients. Corrected carotid flow time and carotid blood flow were measured in the supine, semirecumbent, and PLR positions. Ultrasonographic carotid artery flow and preoperative TTE measurements were compared between patients who developed SAH and those who did not. Receiver operating characteristic (ROC) curve analysis and logistic regression analysis were used to test the association with SAH. RESULTS SAH occurred in 17 of 50 patients. Carotid blood flow in the semirecumbent position and preoperative mitral inflow E velocity could predict SAH, showing an area under the ROC curve of 0.754 (95% CI, 0.612-0.865) and 0.775 (95% CI, 0.634-0.881), respectively. However, according to the multivariate analysis, the independent risk factor for SAH was mitral inflow E velocity (OR 0.918, 95% CI 0.858-0.982, P=0.013). CONCLUSIONS In elderly patients, ultrasonographic carotid artery flow measurements failed to predict the occurrence of SAH. Only preoperative mitral inflow E velocity of TTE was selected as an independent risk factor for SAH.

Figure 1

Corrected carotid flow time was calculated by the measurement of interval between the start of systolic upstroke and the dicrotic notch of the spectral Doppler waveform: a) systole time; b) cycle time. Carotid blood flow was calculated by the measurement of velocity time integral tracing of the c) spectral Doppler signal and d) carotid diameter.

Figure 2

Consort flow diagram.

Figure 3

Hemodynamic parameters. (A) Mean blood pressure in the patients who developed hypotension decreased significantly compared with the baseline value and remained lower until the end of the study compared with patients who did not (P=0.006). (B) However, HR was not significantly changed, remaining close to baseline values in all patients (P=0.972). BL – baseline; semi, semirecumbent position; PLR – passive leg raise position. This figure was created with MedCalc^® Statistical Software (version 13.2, MedCalc Software Ltd.).