The optimal oxytocin infusion rate for preventing uterine atony during cesarean delivery in elderly parturients with prior history of cesarean delivery.

Background: An estimate of 90% effective dose (ED90) of oxytocin infusion has already been proved effective in non-laboring parturients. However, the requirements of oxytocin for elderly parturients with prior history of cesarean delivery (CD) may be higher. The aim of this study was to find the optimum oxytocin infusion rate for preventing uterine atony during CD in elderly parturients with prior history of CD. Method: We performed a randomized, double-blinded study in 120 healthy elderly parturients with prior history of CD scheduled for elective CD under combined spinal-epidural (CSE) anesthesia. Participants were treated with oxytocin infusion randomly at the rates of 0, 4, 8, 12, 16, or 20 IU h-1 after the delivery of infants. Following oxytocin administration, a blinded obstetrician evaluated the uterine tone (UT), verbally describing it using numerical scales (0-10: 0, no UT; 10, optimal UT) as either adequate or inadequate at the time intervals of 3, 6, and 9 min. Maternal adverse effects, requirements for additional uterotonic agents, delivery-placenta delivery time (PD), and estimated blood loss (EBL) were recorded. Results: The 50% effective dose (ED50) and 90% effective dose (ED90) of oxytocin infusion were 14.6 IU h-1 (95% confidence interval 12.0-18.4 IU h-1) and 27.7 IU h-1 (95% confidence interval 22.5-39.4 IU h-1), respectively. As the rate of infusion was increased in parturients, the rescue oxytocin dose and delivery-PD time were decreased. Parturients who received 0 IU h-1 oxytocin at 3, 6, and 9 min obtained lower UT scores than those who received 16 and 20 IU h-1 oxytocin (p < 0.05, respectively). No significant differences were observed among groups in EBL and maternal adverse effects. Conclusion: The infusion rate of oxytocin at 14.57 and 27.74 IU h-1 produces adequate UT in 50% and 90% of elderly parturients with prior history of CD, respectively. An oxytocin infusion rate of 27.7 IU h-1 is suggested to be the optimal dose for preventing uterine atony during CD in elderly parturients with prior history of cesarean delivery. Clinical Trial Registration: [https://www.chictr.org.cn/bin/project/edit?pid=62489], Identifier: [ChiCTR2000038891].

The Intraoperative Median Effective Dose of Oxytocin for Preventing Uterine Atony in Parturients with a Prior History of Caesarean Delivery.

BACKGROUND AND OBJECTIVE: While oxytocin is commonly used for the prevention of uterine atony, its pharmacology may be affected by a prior history of caesarean delivery. The objective of this study was to determine the 50% effective dose (ED50) of bolus oxytocin after caesarean delivery in parturients with and without prior caesarean delivery. METHODS: This was a parallel-group, double-blind, dose-response study using Dixon's up-and-down sequential allocation method to estimate the ED50 of bolus-administered oxytocin in parturients having caesarean delivery under combined spinal-epidural anaesthesia (CSE). Twenty-seven parturients with a history of prior caesarean delivery (With-PCD group) and 26 parturients with no such history (Without-PCD group) were enrolled. Oxytocin was administered as an intravenous bolus at a starting dose of 0.5 units, which was then increased or decreased by 0.25 units at a time. Uterine tone was assessed by the obstetrician as either 'adequate' or 'inadequate' 3 min after delivery of the fetus. Adverse effects, administration of additional uterotonic agents, and estimated blood loss were recorded. RESULTS: The ED50 of oxytocin was greater in the With-PCD group than in the Without-PCD group (0.95 units [95% CI 0.82-1.08] vs. 0.55 units [95% CI 0.38-0.73], P < 0.001). The overall incidence of adverse effects was higher in the With-PCD group than in the Without-PCD group (33.3% vs. 7.7%, P = 0.02). CONCLUSION: The initial bolus dose of oxytocin needed to prevent uterine atony was higher in parturients with prior caesarean delivery than in parturients without prior caesarean delivery. Uterine scarring may contribute to the increased oxytocin requirements of the former group. TRIAL REGISTRATION NUMBER: ChiCTR1900023474; investigator: Wei CN; date of registration: 30 May 2019.

A prediction model using machine-learning algorithm for assessing intrathecal hyperbaric bupivacaine dose during cesarean section.

BACKGROUND: The intrathecal hyperbaric bupivacaine dosage for cesarean section is difficult to predetermine. This study aimed to develop a decision-support model using a machine-learning algorithm for assessing intrathecal hyperbaric bupivacaine dose based on physical variables during cesarean section. METHODS: Term parturients presenting for elective cesarean section under spinal anaesthesia were enrolled. Spinal anesthesia was performed at the L3/4 interspace with 0.5% hyperbaric bupivacaine at dosages determined by the anesthesiologist. A spinal spread level between T4-T6 was considered the appropriate block level. We used a machine-learning algorithm to identify relevant parameters. The dataset was split into derivation (80%) and validation (20%) cohorts. A decision-support model was developed for obtaining the regression equation between optimized intrathecal 0.5% hyperbaric bupivacaine volume and physical variables. RESULTS: A total of 684 parturients were included, of whom 516 (75.44%) and 168 (24.56%) had block levels between T4 and T6, and less than T6 or higher than T4, respectively. The appropriate block level rate was 75.44%, with the mean bupivacaine volume [1.965, 95%CI (1.945,1.984)]ml. In lasso regression, based on the principle of predicting a reasonable dose of intrathecal bupivacaine with fewer physical variables, the model is "Y=0.5922+ 0.055117* X1-0.017599*X2" (Y: bupivacaine volume; X1: vertebral column length; X2: abdominal girth), with λ 0.055, MSE 0.0087, and R2 0.807. CONCLUSIONS: After applying a machine-learning algorithm, we developed a decision model with R2 0.8070 and MSE due to error 0.0087 using abdominal girth and vertebral column length for predicting the optimized intrathecal 0.5% hyperbaric bupivacaine dosage during term cesarean sections.

The Median Effective Dose of Oxytocin Needed to Prevent Uterine Atony During Cesarean Delivery in Elderly Parturients.

PURPOSE: Oxytocin is the first-line agent to prevent and treat uterine atony during cesarean delivery (CD). We compared the effective dose in 50% of the parturients (ED50) of a prophylactic oxytocin bolus during CD in young (<35 years) and old parturients (≥35 years) using Dixon's up-and-down method. PATIENTS AND METHODS: Twenty-eight young parturients (young group) and 25 old parturients (old group) undergoing CD under combined spinal-epidural anesthesia were enrolled. The initial oxytocin bolus was 0.5 IU, with increments or decrements of 0.25 IU. Maternal adverse effects, requirement for additional uterotonic agents, and estimated blood loss were recorded. RESULTS: The ED50 for oxytocin in the old group was higher than that in the young group (1.41 IU; 95% confidence interval, 0.63-2.19) vs 0.66 IU (0.04-1.29), P < 0.001). The total oxytocin dose in the old group was higher than in the young group (5.9 ± 2.9 vs 4.1 ± 2.1 IU, P = 0.01). The estimated blood loss in the older group and young group was 401.2 ± 204.5 mL and 289.3 ± 104.6 mL, respectively (P =0.01). The overall prevalence of adverse effects was higher in the old group than in the young group (68.0% vs 21.4%, P < 0.001). CONCLUSION: The initial bolus and total requirement of oxytocin for preventing uterine atony were higher in old parturients than in young parturients during CD. Advanced maternal age may necessitate higher doses of oxytocin.

Remifentanil for Carboprost-Induced Adverse Reactions During Cesarean Delivery Under Combined Spinal-Epidural Anesthesia.

PURPOSE: Carboprost may induce adverse reactions when used to treat postpartum hemorrhage. We aimed to explore the effects of intravenous infusion of low-dose remifentanil to prevent such reactions. METHODS: We enrolled parturient patients scheduled for elective cesarean section. Anesthesiologist administered combined spinal epidurals at the L3/4 interspace, with 0.5% hyperbaric bupivacaine subarachnoid space injections (1.5-2.5 ml). We randomly divided parturient patients, administered carboprost during surgery, into the remifentanil group (group R) and the control group (group C). Patients in group R received an intravenous target-controlled infusion of remifentanil (target effect-site concentration, 1.5 ng/ml) simultaneously with a carboprost tromethamine injection (250 µg). Patients in group C received a normal saline infusion with carboprost. We recorded and analyzed the incidence of carboprost-related adverse reactions (vomiting, nausea, chest congestion, flushing, hypertension, tachycardia, cough, and shivering), and assessed patient comfort using a numerical rating scale ([NRS], on which 0 was very uncomfortable and 10 was very comfortable). RESULTS: After applying inclusion and exclusion criteria, we conducted statistical analysis of the data from 70 women. The incidence of vomiting was significantly lower in group R than in group C (14.3 vs. 51.4%, p < 0.01); and the incidence of nausea, chest congestion, facial flushing, and hypertension were significantly lower in group R than in group C (all p < 0.01). Furthermore, the patients' comfort scores were significantly higher in group R than in group C (8.0 ± 1.8 vs. 3.6 ± 2.1, p < 0.01). CONCLUSION: Our results demonstrate that an intravenous low-dose remifentanil infusion can effectively prevent carboprost-related adverse reactions during cesarean delivery under combined spinal and epidural anesthesia. CLINICAL TRIAL REGISTRATION: We pre-registered this study at http://www.chictr.org.cn/showproj.aspx?proj=27707 (ChiCTR1800016292).

Abdominal girth and vertebral column length aid in predicting intrathecal hyperbaric bupivacaine dose for elective cesarean section.

Currently, there is no consensus on how to determine the optimal dose of intrathecal bupivacaine for an individual undergoing an elective cesarean section. In this study, we developed a regression equation between intrathecal 0.5% hyperbaric bupivacaine volume and abdominal girth and vertebral column length, to determine a suitable block level (T5) for elective cesarean section patients.In phase I, we analyzed 374 parturients undergoing an elective cesarean section that received a suitable dose of intrathecal 0.5% hyperbaric bupivacaine after a combined spinal-epidural (CSE) was performed at the L3/4 interspace. Parturients with T5 blockade to pinprick were selected for establishing the regression equation between 0.5% hyperbaric bupivacaine volume and vertebral column length and abdominal girth. Six parturient and neonatal variables, intrathecal 0.5% hyperbaric bupivacaine volume, and spinal anesthesia spread were recorded. Bivariate line correlation analyses, multiple line regression analyses, and 2-tailed t tests or chi-square test were performed, as appropriate. In phase II, another 200 parturients with CSE for elective cesarean section were enrolled to verify the accuracy of the regression equation.In phase I, a total of 143 parturients were selected to establish the following regression equation: YT5 = 0.074X1 - 0.022X2 - 0.017 (YT5 = 0.5% hyperbaric bupivacaine volume for T5 block level; X1 = vertebral column length; and X2 = abdominal girth). In phase II, a total of 189 participants were enrolled in the study to verify the accuracy of the regression equation, and 155 parturients with T5 blockade were deemed eligible, which accounted for 82.01% of all participants.This study evaluated parturients with T5 blockade to pinprick after a CSE for elective cesarean section to establish a regression equation between parturient vertebral column length and abdominal girth and 0.5% hyperbaric intrathecal bupivacaine volume. This equation can accurately predict the suitable intrathecal hyperbaric bupivacaine dose for elective cesarean section.

Abdominal girth, vertebral column length and spread of intrathecal hyperbaric bupivacaine in the term parturient.

BACKGROUND: We aimed to test whether abdominal girth and vertebral column length were predictors of spinal hyperbaric bupivacaine spread in term parturients. METHODS: A total of 128 parturients having elective caesarean section under spinal anaesthesia were enrolled. Combined spinal-epidural anaesthesia was performed at the L3/4 interspace, confirmed by ultrasonography. Two mL of 0.5% hyperbaric bupivacaine was injected intrathecally and spinal spread assessed at three-minute intervals. If loss of discrimination of pinprick sensation at the T6 level was not obtained within 15min after injection, 5mL of 2% lidocaine was administered epidurally. Correlation and multiple linear regression were used to analyse the relationship between patient variables, including age, height, weight, abdominal girth, vertebral column length and neonatal biparietal diameter, and the spread of spinal anaesthesia. RESULTS: Two parturients were excluded. Significant univariate correlation with spinal spread existed for height, weight, abdominal girth and vertebral column length (r=-0.446, 0.201, 0.372, P<0.711, respectively, all P<0.05). Multiple linear regression analysis showed that parturients' abdominal girth and vertebral column length were the key determinants of spinal spread (both P<0.0001). The adjusted R2 was 0.742 for the regression equation between abdominal girth, vertebral column length and height of block. CONCLUSION: Parturient abdominal girth and vertebral column length have significant predictive value in determining the cephalad spread of spinal anaesthesia with hyperbaric bupivacaine in term parturients.

Abdominal girth and vertebral column length can adjust spinal anesthesia for lower limb surgery, a prospective, observational study.

BACKGROUND: Studies have shown that abdominal girth and vertebral column length have high predictive value for spinal spread after administering a dose of plain bupivacaine. we designed a study to identify the specific correlations between abdominal girth, vertebral column length and a 0.5% dosage of plain bupivacaine, which should provide a minimum upper block level (T12) and a suitable upper block level (T10) for lower limb surgeries. METHODS: A suitable dose of 0.5% plain bupivacaine was administered intrathecally between the L3 and L4 vertebrae for lower limb surgeries. If the upper cephalad spread of the patient by loss of pinprick discrimination was T12 or T10, the patient was enrolled in this study. Five patient variables and intrathecal plain bupivacaine dose were recorded. Linear regression and multiple regression analyses were performed. RESULTS: Totals of 111 patients and 121 patients who lost pinprick discrimination at T12 and T10, respectively, were analyzed in this study. Linear regression analysis showed that only abdominal girth and plain bupivacaine dose were strongly correlated (r =-0.827 for T12, r = -0.806 for T10; both p < 0.0001). Multiple linear regression analysis showed that both abdominal girth and vertebral column length were the key determinants of plain bupivacaine dose (both p < 0.0001). R(2) was 0.874 and 0.860 for the loss of pinprick discrimination at T12 and T10, respectively. CONCLUSIONS: Our data indicated that vertebral column length and abdominal girth were strongly correlated with the dosage of intrathecal plain bupivacaine for the loss of pinprick discrimination at T12 and T10. The two regression equations were YT12 = 3.547 + 0.045X1-0.044X2 and YT10 = 3.848 + 0.047X1- 0.046X2 (Y, 0.5% plain bupivacaine volume; X1, vertebral column length;and X 2, abdominal girth), which can accurately predict the minimum and suitable intrathecal bupivacaine dose for lower limb surgery to a great extent, separately.