ABSTRACT

Introduction: Maternal arterial hypotension is the most common complication of spinal anesthesia for cesarean section, potentially compromising maternal and fetal safety. The objective of this study was to evaluate whether a simple technical modification, the orientation of the needle bevel, could reduce the incidence of this hypotension.
Methods: A prospective, randomized, comparative study was conducted on 100 parturients (ASA I-III) undergoing emergency cesarean section. Patients were divided into two groups: Group I (n=54) received spinal anesthesia with a conventional cephalad bevel orientation, and Group II (n=46) with a caudad orientation. All participants received 10 mg of hyperbaric bupivacaine and 25 mcg of fentanyl. The primary endpoint was the incidence of hypotension (defined as SBP < 100 mmHg or a drop > 20% from baseline).
Results: The incidence of hypotension was significantly lower in the caudad orientation group (10.8%) compared to the cephalad orientation group (38.8%, p = 0.039). Ephedrine consumption was reduced by over 70% in the caudad group (3.0 ± 1.8 mg vs 11.9 ± 4.2 mg, p < 0.05). Furthermore, 78.3% of patients in the caudad group required no vasopressors, compared to 37% in the cephalad group (p < 0.05). The sensory block level was lower (T5 vs T3) and had a slower onset (time to T6: 10 vs 6 min) in the caudad group, while remaining clinically effective.
Conclusion: Caudad orientation of the needle bevel is a simple, effective, and cost-free technique to improve the safety of obstetric spinal anesthesia. It significantly reduces the incidence of maternal hypotension and vasopressor consumption, at the cost of a slightly slower onset of the anesthetic block.

KEYWORDS

Spinal Anesthesia, Cesarean Section, Hypotension, Obstetric Anesthesia, Needle Orientation, Bupivacaine, Patient Safety.

REFERENCES

1) Cook, T. M., Counsell, D., Wildsmith, J. A. W., & Royal College of Anaesthetists. (2009). Major complications of central neuraxial block: report on the Third National Audit Project of the Royal College of Anaesthetists. British Journal of Anaesthesia, 102(2), 179–190.
2) Hawkins, J. L., Koonin, L. M., Palmer, S. K., & Gibbs, C. P. (1997). Anesthesia-related deaths during obstetric delivery in the United States, 1979-1990. Anesthesiology, 86(2), 277–284.
3) Lorato, S. S., et al. (2025). Incidence and predictors of post spinal anesthesia-induced hypotension. ScienceDirect.
4) Zwane, S. F., et al. (2019). Hypotension during spinal anaesthesia for caesarean section: a prospective cohort study. Southern African Journal of Anaesthesia and Analgesia, 25(1), 23-27.
5) Masha, T. M., et al. (2025). The incidence and associated factors of hypotension during spinal anesthesia. PubMed Central.
6) Kinsella, S. M., & Tuggy, M. (2019). A survey of the management of spinal-induced hypotension for caesarean section. International Journal of Obstetric Anesthesia, 39, 46-52. 
7) Kinsella, S. M. (2018). Hypotension during spinal anaesthesia for caesarean section: Mechanisms, prediction and prevention. Anaesthesia, 73(2), 164-176.
8) Macarthur, A., & Riley, E. T. (2007). Obstetric anesthesia controversies: vasopressor choice for hypotension during cesarean delivery. International Anesthesiology Clinics, 45(1), 115-132.
9) Mercier, F. J., & Augè, M. (2007). Spinal anaesthesia for caesarean section: fluid loading, vasopressors and hypotension. Annales Françaises d’Anesthésie et de Réanimation, 26(7-8), 688-693.
10) Fakherpour, A., Ghaem, H., Fattahi, Z., & Zaree, S. (2018). Maternal and anaesthesia-related risk factors and incidence of spinal anaesthesia-induced hypotension in elective caesarean section: A multinomial logistic regression. Indian Journal of Anaesthesia, 62(1), 36–46.
11) Ngan Kee, W. D., Khaw, K. S., Tan, P. E., Ng, F. F., & Karmakar, M. K. (2009). Placental transfer and fetal metabolic effects of phenylephrine and ephedrine during spinal anesthesia for cesarean delivery. Anesthesiology, 111(3), 506–512.
12) Hasanin, A., Amin, S., Agiza, N., Elsayed, M., Refaat, S., et al. (2019). Norepinephrine infusion for preventing postspinal anesthesia hypotension during cesarean delivery: A randomized dose-finding trial. Anesthesiology, 130(1), 55–62.
13) She, Y. J., et al. (2021). The impact of height on the spread of spinal anesthesia and stress response in parturients undergoing caesarean section: a prospective observational study. BMC Anesthesiology, 21(1), 1-9.
14) Hocking, G., & Wildsmith, J. A. W. (2004). Intrathecal drug spread. British Journal of Anaesthesia, 93(4), 568-578.
15) Sass, L., Khani, M., Natividad, G., et al. (2017). A 3D subject-specific model of the spinal subarachnoid space with anatomically realistic ventral and dorsal spinal cord nerve rootlets. Fluids and Barriers of the CNS, 14(1), 36.
16) Muccio, M., Chu, D., Minkoff, L., et al. (2021). Upright versus supine MRI: effects of body position on craniocervical CSF flow. Fluids and Barriers of the CNS, 18, 61.
17) Kwon, W. K., et al. (2016). Needle Tip Position and Bevel Direction Have No Effect in the Result of Interlaminar Epidural Injections. Pain Physician, 19(4), E545-E552.
18) Somboonviboon, W., Kyokong, O., Charuluxananan, S., et al. (2008). Incidence and risk factors of hypotension and bradycardia after spinal anaesthesia for cesarean section. Journal of the Medical Association of Thailand, 91, 181–187.
19) Barud, A. A., et al. (2025). Incidence and risk factors of hypotension in cesarean section under spinal anesthesia. PubMed.
20) Karnina, R., et al. (2022). Incidence of hypotension, bradycardia, and post-operative nausea and vomiting after spinal anesthesia for cesarean section. Open Access Macedonian Journal of Medical Sciences, 10(A), 1-8.
21) Masha, T. M., et al. (2025). The incidence and associated factors of hypotension during spinal anesthesia. PubMed Central.
22) She, Y. J., Liu, W. X., Wang, L. Y., Ou, X. X., Liang, H. H., & Lei, D. (2021). The impact of height on the spread of spinal anesthesia and stress response in parturients undergoing caesarean section: a prospective observational study. BMC Anesthesiology, 21(1), 298.
23) Zhang, N., He, L., & Ni, J. (2017). Level of sensory block after spinal anesthesia as a predictor of hypotension in parturient. Medicine (Baltimore), 96(25), e7184.
24) Lloyd, R., et al. (2020). Respiratory cerebrospinal fluid flow is driven by the thoracic and lumbar spinal pressures. Journal of Physiology, 598, 5789–5805.
25) Støverud, K., Langtangen, H., Haughton, V., & Mardal, K. (2013). CSF pressure and velocity in obstructions of the subarachnoid spaces. Neuroradiology Journal, 26(2), 218–226.
26) Ni, T., Zhou, Y., Yong, A., Wang, L., & Zhou, Q. (2018). Intra-abdominal pressure, vertebral column length, and spread of spinal anesthesia in parturients undergoing cesarean section: an observational study. PLoS ONE, 13(4), e0195137.
27) Koontz, N. A., et al. (2017). Do superior or inferior interlaminar approach or bevel direction affect epidural spread? American Journal of Roentgenology, 208(5), 1-8.
28) Datta, S., & Alper, M. H. (1980). Anesthesia for cesarean section. Anesthesiology, 53(2), 142–160.
29) Ousley, R., Egan, C., Dowling, K., & Cyna, A. M. (2012). Assessment of block height for satisfactory spinal anaesthesia for caesarean section. Anaesthesia, 67(12), 1348-1352.
30) Antoine, G., Vialles, N., Tanoubi, I., et al. (2005). Spinal anesthesia-induced hypotension: A risk comparison between patients with severe preeclampsia and healthy women undergoing preterm cesarean delivery. Anesthesia & Analgesia, 101(3), 869–875.
31) Rasolonjatovo, T., Ravololonirina, B., Randriamanantany, Z., & Raveloson, N. (2014). Rachianesthésie pour césarienne: facteurs de risque d’apparition de scores d’Apgar inférieur à 7 chez les nouveau-nés malgaches. Pan African Medical Journal, 19, 193.