What question did this study set out to answer?

This study aims to determine if positional changes in carotid corrected flow time can predict spinal anesthesia-induced hypotension in term parturients.

May 31, 2026International Journal of Women s Health0 citationsOpen Access

Position-Induced Change in Carotid Corrected Flow Time Predicts Spinal Hypotension in Cesarean Delivery

SHShuai Hao YCYinghao Cao TZTieying Zhang

Key Points

This study aims to determine if positional changes in carotid corrected flow time can predict spinal anesthesia-induced hypotension in term parturients.
Single-center prospective observational study with 54 healthy term parturients (≥ 37 weeks, ASA I–II).
Measured corrected flow time and respiratory variation before neuraxial block using high-resolution carotid Doppler.
Primary outcome was the incidence of spinal anesthesia-induced hypotension within 15 minutes post-induction.
34 out of 54 participants developed spinal anesthesia-induced hypotension (63%).
The SAIH group had shorter supine corrected flow time (330.30 ms vs 351.14 ms, P < 0.001) and greater δcFT (22.55 ms vs 0.23 ms, P < 0.001).
δcFT showed superior predictive accuracy (AUC 0.872) compared to supine cFT (AUC 0.769) and δVpeak (AUC 0.50–0.52).

Abstract

Background: Spinal anesthesia-induced hypotension (SAIH) complicates 50– 70% of cesarean deliveries, posing maternal-fetal risks. This prospective, single-center observational study (ClinicalTrials.gov: ChiCTR2300077480) evaluated whether pre-induction positional change in carotid corrected flow time (δcFT) predicts SAIH in term parturients. Methods: In this single-center prospective observational study, 54 healthy term parturients (≥ 37 weeks, ASA I–II), high-resolution carotid Doppler measured corrected flow time (cFT) and respiratory variation in peak velocity (δVpeak) in supine and left-lateral positions immediately before neuraxial block. The primary outcome was SAIH incidence within 15 minutes post-induction. Results: Of 54 participants analyzed, 34 developed SAIH (63%). The SAIH group exhibited significantly shorter supine cFT (330.30± 18.44 vs 351.14± 19.57 ms, P < 0.001) and greater positional cFT increase (δcFT: 22.55± 14.29 vs 0.23± 13.30 ms, P < 0.001). δcFT demonstrated superior discriminatory accuracy (AUC 0.872, 95% CI 0.772– 0.972, P < 0.001) compared with supine cFT (AUC 0.769) and δVpeak (AUC 0.50– 0.52). Optimal δcFT threshold was 6.49 ms (sensitivity 94.1%, specificity 75.0%). Exploratory multivariable logistic regression analysis suggested that δcFT was associated with SAIH after adjustment for prespecified covariates (OR 1.125 per 1-ms increase, 95% CI 1.049– 1.206, P =0.001), whereas higher supine cFT was associated with a lower risk (OR 0.934, P =0.002). δcFT correlated significantly with the magnitude of blood pressure decrease (r=0.437, P =0.001). Interobserver reliability was excellent (ICC 0.969). Conclusion: Pre-induction δcFT could be a promising noninvasive predictor of SAIH. Bedside assessment of positional changes in cFT might identify high-risk parturients and guide targeted prophylactic strategies. δVpeak lacked predictive utility in spontaneously breathing patients. Further external validation studies are warranted. Keywords: spinal anesthesia, cesarean section, hypotension, carotid ultrasound, corrected flow time, peak-velocity respiratory variation

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