The Effect of Spinal Hypotension and Anesthesia-to-delivery Time Interval on Neonatal Outcomes in Planned Cesarean Delivery

Abstract

A natomic changes associated with pregnancy may render conduct of neuraxial procedures in parturients more difficult. The standard position for a neuraxial block requires a patient to sit on a bed with the spine flexed and legs supported on a stool, but spinal flexion may be improved by instead sitting cross-legged on the bed. Given the lack of prospective studies on this topic, the aim of this study was ultrasonographic assessment of the paramedian target area's size when a pregnant woman sits in the crosslegged position (CLP) for neuraxial needle placement compared with standard sitting position (SP). The authors hypothesized that a CLP would increase the measured lengths of the posterior longitudinal ligament (PLL) indicating an improved acoustic window between vertebrae.From April to July 2016, 30 pregnant, nonlaboring women at 37 weeks or more gestation were recruited when they arrived at the Obstetric Care Unit during the first stage of labor, for an induction of labor, or for an elective cesarean delivery (all while exhibiting no signs of painful contractions). Exclusion criteria were as follows: language barrier, congenital spine abnormality, a history of spinal trauma or surgery, or women in advanced first stage of labor.Demographic data recorded and patients were first asked to sit with their shoulders relaxed, chin to chest, and back curled outward. Then the patients were asked to sit in both study positions-the standard position and the CLP while hugging a pillow. Ultrasonographic identification of the L3-L4 interspace and the PLL measurement at that level were performed by 2 separate scanners. Patients were asked to record their comfort level in each position (5 = very comfortable, and 1 = very uncomfortable). The primary outcome of the study, increase in length of the PLL, was accompanied by secondary outcomes of evaluated increases in length of the ligamentum flavum and interlaminar distance and subject comfort levels.Records for 28 were included in the analysis. Results demonstrated that the ultrasonographically visualized length of the PLL was significantly greater when measured in the CLP compared with SP. In addition, patients reported comparable comfort levels for both CLP and SP.The study did not assess effectiveness of using CLP during placement of neuraxial anesthesia in obstetric patients. In addition, scanning anesthesiologists were not

Spinal Hypotension and Time from Spinal-to-Delivery in Scheduled Cesarean Deliveries: Association with Neonatal Acidosis

“…The incidence of neonatal acidosis in our study is similar to what has been reported. 2 4 5 17 Unlike prior studies though, we did not find an association between spinal-induced hypotension and other adverse neonatal outcomes, nor did we find a significant difference in spinal-to-delivery time stratified by neonatal acidosis. The findings of our study may be due to tighter blood pressure control with the use of prophylactic vasopressor infusions, which became routine practice at our center in 2019.…”

“…5 Knigin et al similarly reported that longer anesthesia-to-delivery times were significantly associated with increased risk for neonatal acidosis. 4 Hassanin et al found spinal-to-delivery time of >27 minutes to be predictive of a umbilical artery pH < 7.2 in their study cohort. 13 We did not find this association in our study cohort, perhaps because prophylactic vasopressors allow for optimal control of maternal blood pressures after spinal anesthesia, making time from spinal-to-delivery less important.…”

“…10 14 18 19 20 However, the practice has not yet been universally adopted, as is evidenced by recently published studies examining risk factors for neonatal acidosis in scheduled CD. 2 4 5…”

“…Knigin et al conducted a retrospective study of sustained hypotension after spinal in scheduled CD performed between 2007 and 2017 at two high-volume centers in Jerusalem, and only 52.7% of patients received some type of vasopressor treatment. 4 Bligard et al conducted a single-center retrospective study from 2004 to 2014 examining the association of fetal acidemia with adverse neonatal outcomes in scheduled CD, and the authors reported vasopressor use at a rate of 71.9%. 2 Rimsza et al described a higher rate of vasopressor administration in a population who underwent scheduled CD at a tertiary care center between 2014 and 2017.…”

“…This methodology and the thresholds used to define sustained hypotension were adapted from a previously published study. 4…”