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Published on: April 28, 2023
Position-Induced Change in Carotid Corrected Flow Time Predicts Spinal Hypotension in Cesarean Delivery
Shuai Hao1,2, Yinghao Cao2, Tieying Zhang3
1Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, People's Republic of China.
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.
