Cardiovascular adaptation to spinal anesthesia-induced hypotension during scheduled cesarean section: the paradigm of ionized calcium and nitric oxide in a prospective cohort study
4 affiliations
- 1Department of Physiology, Faculty of Basic Medical Sciences, University of Calabar, Calabar, Nigeria
- 2Department of Surgery and Specialties, Higher Institute of Medical Technology, Yaounde, Cameroon
- 3Department of Didactics, Faculty of Sciences of Education, University of Yaounde 1, Yaounde, Cameroon
- 4Department of Medical Physiology, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Huye, Rwanda
Abstract
Background: Maternal arterial hypotension occurs in 55–90% of cesarean sections performed under spinal anesthesia. While sympatholysis and aortocaval compression are conventional explanations, refractory cases suggest possible biochemical contributors beyond sympatholysis. We hypothesized that an acute deficit in ionized calcium coupled with endothelial mediator overproduction may constitute a “double lock” mechanism that contributes to hemodynamic decompensation. This prospective observational study examined these associations.
Methods: A prospective, single-center analytical study was conducted from June 2025 to February 2026 at the Centre Hospitalier d’Essos, Yaoundé, enrolling 80 ASA I–II parturients undergoing elective cesarean section under spinal anesthesia. Hemodynamic parameters (SBP, DBP, MAP, HR, SpO₂), plasma electrolytes (Na⁺, K⁺, Cl⁻, iCa²⁺), and vasoactive mediators (nitric oxide [NO], prostaglandin I₂ [PGI₂]) were measured at baseline (T0) and 10 min post-induction (T1).
Results: Hypotension was confirmed in 78% of participants. MAP fell by 23% (92.4 ± 8.1 to 71.2 ± 9.5 mmHg; p < 0.001). Ionized calcium dropped significantly below the critical threshold (1.18 ± 0.06 to 0.98 ± 0.04 mmol/L; p < 0.01), correlating strongly with SBP decline (r = 0.72; p < 0.01). NOₓ increased by 37.9% and PGI₂ by 25.3% (both p < 0.01). Na⁺, K⁺, and Cl⁻ remained stable.
Conclusion: Spinal anesthesia-induced hypotension in parturients was associated with concurrent acute ionized calcium reduction and elevated vasoactive mediators (NOₓ and PGI₂), consistent with a “double lock” hypothesis. These findings are exploratory and hypothesis-generating. They support prospective interventional investigation of ionized calcium and vasoactive mediators as contributors to hemodynamic decompensation during spinal anesthesia for cesarean section.
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BibTeX
@article{mohamed2026cardiovascular,
title = {{Cardiovascular adaptation to spinal anesthesia-induced hypotension during scheduled cesarean section: the paradigm of ionized calcium and nitric oxide in a prospective cohort study}},
author = {Mpeyou Sani Mohamed and Daniel Ewa Ikpi and Ngokoh Ghislain Nyemji and Nga Nomo Serge Vivier and Ndam Gbetnkom Pascal and Favour Nyoh Beshel and Daniel Udofia Owu},
journal = {BMC Anesthesiology},
year = {2026},
month = aug,
doi = {10.1186/s12871-026-04135-w},
url = {https://doi.org/10.1186/s12871-026-04135-w},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Cardiovascular adaptation to spinal anesthesia-induced hypotension during scheduled cesarean section: the paradigm of ionized calcium and nitric oxide in a prospective cohort study
AU - Mpeyou Sani Mohamed
AU - Daniel Ewa Ikpi
AU - Ngokoh Ghislain Nyemji
AU - Nga Nomo Serge Vivier
AU - Ndam Gbetnkom Pascal
AU - Favour Nyoh Beshel
AU - Daniel Udofia Owu
PY - 2026
DA - 2026/08/01
JO - BMC Anesthesiology
DO - 10.1186/s12871-026-04135-w
UR - https://doi.org/10.1186/s12871-026-04135-w
AB - Background: Maternal arterial hypotension occurs in 55–90% of cesarean sections performed under spinal anesthesia. While sympatholysis and aortocaval compression are conventional explanations, refractory cases suggest possible biochemical contributors beyond sympatholysis. We hypothesized that an acute deficit in ionized calcium coupled with endothelial mediator overproduction may constitute a “double lock” mechanism that contributes to hemodynamic decompensation. This prospective observational study examined these associations. Methods: A prospective, single-center analytical study was conducted from June 2025 to February 2026 at the Centre Hospitalier d’Essos, Yaoundé, enrolling 80 ASA I–II parturients undergoing elective cesarean section under spinal anesthesia. Hemodynamic parameters (SBP, DBP, MAP, HR, SpO₂), plasma electrolytes (Na⁺, K⁺, Cl⁻, iCa²⁺), and vasoactive mediators (nitric oxide [NO], prostaglandin I₂ [PGI₂]) were measured at baseline (T0) and 10 min post-induction (T1). Results: Hypotension was confirmed in 78% of participants. MAP fell by 23% (92.4 ± 8.1 to 71.2 ± 9.5 mmHg; p < 0.001). Ionized calcium dropped significantly below the critical threshold (1.18 ± 0.06 to 0.98 ± 0.04 mmol/L; p < 0.01), correlating strongly with SBP decline (r = 0.72; p < 0.01). NOₓ increased by 37.9% and PGI₂ by 25.3% (both p < 0.01). Na⁺, K⁺, and Cl⁻ remained stable. Conclusion: Spinal anesthesia-induced hypotension in parturients was associated with concurrent acute ionized calcium reduction and elevated vasoactive mediators (NOₓ and PGI₂), consistent with a “double lock” hypothesis. These findings are exploratory and hypothesis-generating. They support prospective interventional investigation of ionized calcium and vasoactive mediators as contributors to hemodynamic decompensation during spinal anesthesia for cesarean section.
SN - 1471-2253
ER -