AUTHOR=Wu Haixing , Chen Ting , Xie Xiyuan , Ning Jing , Han Yupeng , Sooranna Suren Rao , Huang Qiuxia , Wu Han , Lin Rong , Xue Hailan , Lin Liang , Wu Xiaodan 

TITLE=Preoperative inferior vena cava-abdominal aorta ultrasound examination to guide the positioning of spinal anesthesia to reduce post-spinal hypotension: a prospective, randomized trial

JOURNAL=Frontiers in Medicine

VOLUME=Volume 12 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2025.1641899

DOI=10.3389/fmed.2025.1641899

ISSN=2296-858X

ABSTRACT=BackgroundThe effectiveness of a 15° left-lateral tilt for alleviating the inferior vena cava (IVC) compression caused by a gravid uterus has been questioned. This study assessed the benefits of conducting pre-spinal anesthesia IVC-abdominal aorta ultrasound examinations and utilizing the IVC to abdominal aorta (IVC/Ao) ratio as a guide for post-spinal anesthesia positioning.Methods200 parturients undergoing cesarean section were randomized 1:1 into an ultrasound-guided and a control group (groups U and C, respectively). The parturients in group C were positioned with a 15° left-lateral tilt, while those in group U had the operating table tilted to achieve the maximum IVC:Ao diameter, as determined by preoperative ultrasound, which indicated the maximum IVC:Ao diameter. The primary endpoint was the incidence of hypotension in parturients, defined as the period from the completion of intrathecal drug injection (time A) to when they were placed in the supine position (time B). Secondary outcomes included total vasopressor use, umbilical cord blood parameters (such as the pH and base excess values of the umbilical artery) immediately after birth, and Apgar scores at 1 and 5 min for the neonate.ResultsThe incidence of hypotension from the end of spinal anesthesia until the supine position was lower in group U (60.8%, n = 79) compared to group C (80%, n = 80) for the parturients included in the statistical analysis (risk difference = −0.192 (95% CI −0.325 to −0.050), p = 0.010). Furthermore, the usage of the vasoactive drug, metaraminol, in group U was lower than in group C [1 (0, 1.5) vs. 1 (0.5, 1.5)], with a mean difference of 0.283 (95% CI 0.044 to 0.522), p = 0.012.ConclusionConducting an IVC-abdominal aorta ultrasound examination before spinal anesthesia in parturients and using the IVC/Ao ratio to guide post-spinal anesthesia positioning reduced the incidence and frequency of hypotension as well as the dose of vasopressors required after surgery.Clinical trial registrationhttps://www.chictr.org.cn/showproj.html?proj=166587, identifier ChiCTR2200059888.