Optimal intrathecal hyperbaric bupivacaine dose with opioids for cesarean delivery: a prospective double-blinded randomized trial

BackgroundSingle-shot spinal anesthesia is commonly used for cesarean delivery. Achieving adequate anesthesia throughout surgery needs to be balanced with associated complications. We investigated the optimal dose of intrathecal hyperbaric bupivacaine, co-administered with opioids, for anesthesia for cesarean delivery.MethodsThis prospective, randomized, double-blinded, dose-ranging trial included parturients scheduled to undergo cesarean delivery under spinal anesthesia. An epidural catheter was first inserted at the T11–12 vertebral interspace, followed by spinal anesthesia at the L2–3 or L3–4 vertebral interspace. Subjects were randomly assigned to one of seven doses of intrathecal hyperbaric bupivacaine 0.5% (6, 7, 8, 9, 10, 11 or 12 mg), with added 15 μg fentanyl and 75 μg morphine. Successful induction of anesthesia (success_ind) was defined as achievement of bilateral sensory loss to cold at the T6 dermatome or higher, within 10 minutes. Successful maintenance of anesthesia (success_main) was defined by no epidural supplementation within 60 minutes of intrathecal injection. The effective doses for 50% (ED₅₀) and 95% (ED₉₅) of patients were estimated using logistic regression analysis.ResultsThe ED₅₀ and ED₉₅ for success_main were 6.0 mg (95% CI: 4.5 to 7.5 mg) and 12.6 mg (95% CI: 7.9 to 17.2 mg), respectively. The incidence of respiratory discomfort and maternal satisfaction scores did not differ significantly between dose groups. Phenylephrine dose and nausea/vomiting incidence increased with increasing doses of bupivacaine.ConclusionUnder study conditions, our results suggest that 12.6 mg of intrathecal bupivacaine, administered with fentanyl and morphine, is required to achieve adequate intraoperative analgesia without the need for epidural supplemention.     

The effect of posture and baricity on the spread of intrathecal bupivacaine for elective cesarean delivery

Posture and baricity during induction of spinal anesthesia with intrathecal drugs are believed to be important in determining spread within the cerebrospinal fluid. In this double-blind prospective study, 150 patients undergoing elective cesarean delivery were randomized to receive a hyperbaric, isobaric, or hypobaric intrathecal solution of 10 mg bupivacaine during spinal anesthesia induced in either the sitting or right lateral position. After an intrathecal injection using a combined-spinal technique patients were placed in the supine wedged position. We determined the densities of the three intrathecal solutions from a previously validated formula and measured using a DMA-450 density meter. Data collection included sensory level, motor block, episodes of hypotension, and ephedrine use. Statistical analysis included analysis of variance and Cuzick's trend. In the lateral position, baricity had no effect on the spread of sensory levels for bupivacaine compared to the sitting position, where there was a statistically significant difference in spread with the hypobaric solution producing higher levels of analgesia than the hyperbaric solution (P = 0.002). However, the overall differences in maximal spread only differed by one dermatome, with the hyperbaric solution achieving a median maximum sensory level to T3 compared with T2 for the isobaric and hypobaric solutions. Motor block was significantly (P = 0.029) reduced with increasing baricity and this trend was significant (P = 0.033) for the lateral position only. Hypotension incidence and ephedrine use increased with decreasing baricity (P = 0.003 and 0.004 respectively), with the hypobaric sitting group having the most frequent incidence of hypotension (76%) as well as cervical blocks (24%; P = 0.032).     

The influence of baricity on the haemodynamic effects of intrathecal bupivacaine 0.5%

This study compared the haemodynamic effects of subarachnoid block with plain bupivacaine 0.5% (dextrose-free), heavy bupivacaine 0.5% (in dextrose 8%) and a mixture of these two solutions, i.e. bupivacaine 0.5% in dextrose 4%. Thirty-six male patients, aged 55-89 years, undergoing transurethral surgery were recruited. Invasive systolic arterial and central venous pressures were recorded at 5-s intervals after the block was initiated using a computerised data-collection system. The height of sensory blockade was recorded at 5-min intervals. No preload was given and episodes of hypotension were treated with colloid (8 ml x kg(-1)) and, if this was ineffective, a metaraminol infusion. Systolic arterial and central venous pressures decreased in all three groups following block (p < 0.05). These decreases were more rapid in onset in the heavy bupivacaine group compared with plain bupivacaine group (p < 0.005). Patients in the heavy bupivacaine group also had a greater requirement for early treatment of hypotension (< 10 min) and treatment with metaraminol (p < 0.05). The onset of sensory blockade was more rapid in the heavy group compared with the mixed group, although final sensory levels were similar. The onset of haemodynamic and sensory changes are more rapid when using heavy bupivacaine intrathecally. This leads to a higher and earlier incidence of hypotension and requirement for treatment.     

Ultra-low dose combined spinal-epidural anesthesia with intrathecal bupivacaine 3.75 mg for cesarean delivery: a randomized controlled trial

BACKGROUND: We wished to investigate the feasibility of an ultra low-dose combined spinal-epidural technique in providing surgical anesthesia for uncomplicated cesarean deliveries in a randomized, double-blind controlled trial. METHOD: Forty-four normotensive, non-obese patients were randomized to receive either intrathecal hyperbaric bupivacaine 3.75 mg (low dose group, n=22) or 9 mg (conventional group, n=22), in addition to intrathecal fentanyl 25 microg, morphine 100 microg, and epidural 1.5% lidocaine 3 mL. Sensorimotor anesthesia and hemodynamic data were assessed at 2.5-min intervals for the first 15 min. RESULTS: The maximal sensory block achieved in the low-dose group was significantly lower than that in the conventional group (median T3, [range T2-T6] vs. T2 [C2-T6], P<0.001) with a longer time taken to reach maximal sensory block. The low-dose group had less motor block, faster sensory regression to T10 dermatome and faster motor recovery to Bromage 0 (all P<0.001). The block failed to reach T6 bilaterally within 10 min in one patient in the low-dose group and two in the conventional group, with no significant difference in the need for epidural supplementation before or after delivery of the baby. The low-dose group experienced less hypotension (14% vs. 73%, P<0.001) with less ephedrine usage (0.68 vs. 17.5 mg, P<0.001). There was no difference in operating conditions and other side effects (shivering, pruritus). CONCLUSION: We conclude that this technique results in a significantly lower incidence of maternal hypotension and has a role in high-risk parturients in whom maintenance of stable hemodynamics is imperative.     

Performance of non-invasive stroke volume variation during passive leg raising as a predictor of hypotension following induction of spinal anesthesia for elective cesarean delivery: a single cohort study

BackgroundSpinal anesthesia for cesarean delivery is accompanied by hypotension in up to 70% of cases. To date, there is no gold standard for predicting hypotension after spinal anesthesia for cesarean delivery. The Clearsight™ device is a non-invasive system that uses a digital cuff to calculate stroke volume. We hypothesized that stroke volume variation induced with passive leg raising before spinal anesthesia for elective cesarean delivery could predict the occurrence of hypotension.MethodsWe conducted a prospective observational study, including third trimester parturients undergoing elective cesarean delivery with spinal anesthesia. We analyzed the stroke volume variation performance for predicting hypotension. Stroke volume was collected in the semi-recumbent position (baseline) and during passive leg raising before spinal anesthesia. Systolic arterial blood pressure measurement was followed for 15 min after spinal anesthesia. Hypotension was defined as a ≥20% decrease from the baseline measurement. All parturients received appropriate hypotension prophylaxis.ResultsData from 42 parturients were analyzed. Hypotension occurred in 45%. The area-under-the curve for predicting hypotension using the stroke volume variation was 0.83 (95% CI 0.68 to 0.98; P=0.001). The best cut-off value for predicting hypotension was 7%, having a sensitivity of 87% (95% CI 0.70 to 0.99) and a specificity of 83% (95% CI 0.69 to 0.97).ConclusionIn our study of third trimester parturients undergoing cesarean delivery and receiving appropriate hypotension prophylaxis, a digital non-invasive monitoring device of stroke volume variation analysis was useful for predicting the occurrence of hypotension after spinal anesthesia.     

Effects of meperidine,pentazocine, bupivacaine and lidocaine in spinal anesthesia for cesarean section

Key words  spinal anesthesia meperidine - pentazocine - bupivacaine - lidocaine - cesarean section     

An open-label randomized controlled clinical trial for comparison of continuous phenylephrine versus norepinephrine infusion in prevention of spinal hypotension during cesarean delivery

BackgroundDuring spinal anesthesia for cesarean delivery phenylephrine is the vasopressor of choice but can cause bradycardia. Norepinephrine has both β- and α-adrenergic activity suitable for maintaining blood pressure with less bradycardia. We hypothesized that norepinephrine would be superior to phenylephrine, requiring fewer rescue bolus interventions to maintain blood pressure.MethodsEighty-five parturients having spinal anesthesia for elective cesarean delivery were randomized to Group P (phenylephrine 0.1 μg/kg/min) or Group N (norepinephrine 0.05 μg/kg/min) fixed-rate infusions. Rescue bolus interventions of phenylephrine 100 μg for hypotension, or ephedrine 5 mg for bradycardia with hypotension, were given as required to maintain systolic blood pressure. Maternal hemodynamic variables were measured non-invasively.ResultsThere was no difference between groups in the proportion of patients who required rescue vasopressor boluses (Group P: 65.8% [n=25] vs. Group N: 48.8% [n=21], P=0.12). The proportion of patients who received ⩾1 bolus of phenylephrine was similar between groups (Group P: 52.6% [n=20] vs. Group N: 46.5% [n=20], P=0.58). However, more patients received ⩾1 bolus of ephedrine in the phenylephrine group (Group P: 23.7% [n=9] vs. Group N: 2.3% [n=1], P <0.01). The incidence of emesis was greater in the phenylephrine group (Group P: 26.3% vs. Group P: 16.3%, P <0.001). Hemodynamic parameters including heart rate, the incidence of bradycardia, blood pressure, cardiac output, cardiac index, stroke volume, and systemic vascular resistance and neonatal outcome were similar between groups (all P <0.05).ConclusionNorepinephrine fixed-rate infusion has efficacy for preventing hypotension and can be considered as an alternative to phenylephrine.     

Maternal sedation during scheduled versus unscheduled cesarean delivery: implications for skin-to-skin contact

BackgroundEarly maternal skin-to-skin contact confers numerous benefits to the newborn, but maternal sedation during cesarean delivery could have safety implications for early skin-to-skin contact in the operating room. We compared patient-reported and observer-assessed levels of sedation during unscheduled and scheduled cesarean deliveries.MethodsLaboring women undergoing unscheduled cesarean delivery with epidural anesthesia, and scheduled cesarean delivery with spinal anesthesia were enrolled. Sedation levels, measured using patient-reported (1=least sedated to 10=most sedated) and observer-assessed (0=most sedated to 5=least sedated) scales, were evaluated at baseline and 15, 30, 45, and 60 min following a T4 sensory level. The primary outcomes were patient-reported sedation at 45 min and the areas under the sedation curves.ResultsPatient-reported levels of sedation were greater at 45 min in laboring women undergoing unscheduled (median 7.5, IQR 5–9) versus scheduled cesarean delivery (median 4, IQR 3–6) (difference in medians 3.5, 99% CI 0 to 5). Observer-assessed sedation was not different between groups. The area under the time curve for patient-reported sedation was greater in the unscheduled group, median difference 162 score min (95% CI 52 to 255). The area under the time curve for observer-assessed sedation was greater in the unscheduled group, median difference 26 score min (99% CI 0 to 41). Times to skin-to-skin contact and breastfeeding were not different.ConclusionsWomen undergoing unscheduled cesarean deliveries are more sedated than women undergoing scheduled cesarean deliveries. Skin-to-skin protocols for cesarean deliveries must consider maternal sedation and anesthesiologists should use sedating medications judiciously.     

相同浓度的左旋布比卡因、罗比卡因与布比卡因硬膜外腔给药用于剖宫产术时效性的比较

目的比较左旋布比卡因、罗比卡因和布比卡因用于硬膜外麻醉剖宫产术的阻滞效果、母婴安全和药物不良反应.方法采用随机双盲法,将48例择期剖宫产手术的足月单胎产妇分为三组：0.5%左旋布比卡因组（L组）17例、0.5%罗比卡因组（R组）15例和0.5%布比卡因组（B组）16例.记录硬膜外腔给药后产妇的感觉阻滞和运动阻滞的起效和持续时间、肌松满意程度、麻醉质量评价、恶心和呕吐等不良反应及术中心率、血压、脉搏血氧饱和度和新生儿1 min和5 min Apgar评分.结果产妇的一般情况、新生儿的Apgar评分组间无显著性差异;三组术中低血压及其他不良事件（恶心和呕吐）的发生率无显著性差异;各组的麻醉质量（术中的疼痛评分和肌松满意度）基本一致;感觉阻滞起效和维持时间组间无显著性差异,运动阻滞改良Bromage评分为1分的起效时间和持续时间组间有显著性差异.结论常用量0.5%左旋布比卡因、罗比卡因和布比卡因用于剖宫产手术的硬膜外麻醉时具有相似的麻醉效能和安全性.     

A survey of the management of spinal-induced hypotension for scheduled cesarean delivery

BackgroundIntravenous fluids and vasopressors are used for managing spinal-induced hypotension during cesarean delivery, but the choice of vasopressor and the type and timing of fluid administration remain controversial.MethodsWe conducted an electronic survey of all members of the Society for Obstetric Anesthesia and Perinatology between February and March 2007 to determine their preferences for preventing and treating spinal-induced hypotension with respect to fluid and vasopressor administration.ResultsThe response rate was 292/746 (39%). Fifty percent worked in academic institutions and 56% had >50% of their clinical responsibility to obstetric anesthesia. For prophylaxis, 35% used fluid preloading, 30% fluid preloading with vasopressors, and 12% fluid co-loading with vasopressors. Of those using vasopressors for prophylaxis, 32% used ephedrine, 26% used phenylephrine, and 33% based their choice on heart rate. For treatment, 32% used ephedrine, 23% used phenylephrine, and 41% used either agent based on heart rate. Anesthesiologists in academic practice were less likely to use fluid preloading only (P = 0.028) and more likely to use fluid co-loading and vasopressors (P = 0.003). They were also more likely to administer phenylephrine for prophylaxis compared with those in private practice (P = 0.042).ConclusionSignificant variations in practice exist in the prevention and treatment of spinal-induced hypotension. Fluid preloading and the prophylaxis and treatment of hypotension with ephedrine continue to be common practices.     

Low-dose intravenous dexmedetomidine reduces shivering following cesarean delivery: a randomized controlled trial

BackgroundIntravenous dexmedetomidine 30 µg reduces shivering after cesarean delivery but can result in sedation and dry mouth. We hypothesized that prophylactic administration of 10 µg of IV dexmedetomidine would reduce the patient-reported severity of shivering after cesarean delivery, without an increased incidence of side effects.MethodsAfter institutional review board approval and informed written consent, women undergoing scheduled cesarean delivery with spinal or combined spinal-epidural anesthesia were randomized to receive either intravenous normal saline or dexmedetomidine 10 µg immediately after delivery. The primary outcome was a patient-rated subjective shivering score using a 10-cm visual analog scale at 30 and 60 min after arrival in the Post-Anesthesia Care Unit. Secondary outcomes included subjective scores for pain, nausea, itching, dry mouth, and sedation, as well as 24-h medication administration and investigator-rated observations of shivering, vomiting, pruritus, and sedation. Repeated measures ANOVA with Tukey-Kramer multiple-comparison test was applied for primary outcomes.ResultsOne hundred patients were enrolled, and 85 completed the study and were included in analysis. The mean ± SD shivering score in the dexmedetomidine group was significantly lower by repeated measures analysis than among controls across the first 60 min (P=0.0002), and individually at both 30 and 60 min (placebo 1.8 ± 2.6 vs. dexmedetomidine 0.6 ± 1.4 at 30 min; 1.2 ± 2.1 vs. 0.3 ± 0.6 at 60 min; both P <0.01). Patient-rated and observer-rated side effects did not significantly differ between groups.ConclusionsProphylactic administration of intravenous dexmedetomidine 10 µg after delivery reduces shivering without notable side effects.     

The effect of baricity of intrathecal morphine in children receiving tetracaine spinal anaesthesia for cardiac surgery: a preliminary report

BACKGROUND: This prospective, randomized study examined the effect of baricity of intrathecal preservative-free morphine on the duration of postoperative analgesia and incidence of side-effects in infants and children receiving high spinal anaesthesia with hyperbaric tetracaine in combination with a light general anaesthetic. METHODS: Fourteen infants and children, aged 7-91 months, undergoing repair of either uncomplicated atrial or ventricular septal defects, were randomized to receive either 10 microg x kg(-1) of intrathecal morphine in combination with 0.5% tetracaine D10 (hyperbaric morphine group) or intrathecal morphine mixed with saline and injected sequentially after the administration of 0.5% tetracaine D10 (hypobaric morphine group). After spinal injection, patients were positioned in 30 degrees of Trendelenburg for a minimum of 10 min. Postoperatively, patients were monitored for a minimum of 12 h. Pain scores and the incidence and severity of side-effects were recorded every 1 h. RESULTS: All patients were extubated at the conclusion of surgery without any incidence of respiratory depression. There was a decreased incidence of vomiting in the hypobaric morphine group and no significant difference in the duration of analgesia. CONCLUSIONS: When intrathecal morphine is administered in conjunction with a hyperbaric tetracaine spinal to paediatric cardiac patients in the head down position, sequential administration of the hypobaric solution may mitigate side-effects.     

布比卡因复合右美托咪定在剖宫产术蛛网膜下腔麻醉中的安全性和有效性

目的探讨布比卡因复合右美托咪定在剖宫产术蛛网膜下腔麻醉(腰麻)的安全性和有效性。方法择期腰麻下行剖宫产术的产妇150例,年龄20～35岁,体重60～85 kg,随机分为三组,B组:0.5%布比卡因9 mg;FB组:0.5%布比卡因7.5 mg+芬太尼20μg;DB组:0.5%布比卡因7.5 mg+右美托咪定5μg。记录产妇感觉和运动阻滞起效时间、持续时间,以及低血压、寒战、恶心呕吐等不良反应发生情况。结果 B组、FB组和DB组感觉阻滞起效时间分别为(14.8±2.9)s、(15.5±2.2)s和(12.3±1.6)s,DB组明显短于B组和FB组,B组明显短于FB组(P0.05)。B组、FB组和DB组感觉阻滞持续时间分别为(122.3±23.5)min、(108.7±21.4)min和(147.3±18.0)min,DB组明显长于B组和FB组,B组明显长于FB组(P0.05)。B组、FB组和DB组运动阻滞起效时间分别为(3.4±1.1)min、(3.2±0.8)min和(2.8±0.7)min,DB组明显短于B组和FB组(P0.05)。B组、FB组和DB组运动阻滞持续时间分别为(162.1±24.5)min、(141.3±21.9)min和(188.5±21.7)min,DB组明显长于B组和FB组,B组明显长于FB组(P0.05)。DB组产妇低血压、寒战、术中及术后恶心呕吐的发生率均明显低于B组(P0.05),且DB组低血压发生率明显低于FB组(P0.05)。结论剖宫产术中布比卡因复合右美托咪定的腰麻效果优于复合芬太尼,且安全性更高。     

Intrathecal bupivacaine versus chloroprocaine for transvaginal cervical cerclage placement: a retrospective cohort study

BackgroundBupivacaine is commonly used in spinal anesthesia for cervical cerclage placement, but its long duration of action can delay hospital discharge. Chloroprocaine has a short duration of action and has re-emerged as an agent for ambulatory neuraxial anesthesia. There are limited data comparing intrathecal bupivacaine and chloroprocaine when used for cerclage placement. This retrospective study compares the time to hospital discharge between these drugs when used in spinal anesthesia for cervical cerclage placement.MethodsA retrospective analysis of patients who underwent transvaginal cerclage placement under neuraxial anesthesia with intrathecal hyperbaric bupivacaine or plain chloroprocaine between January 1, 2015 and October 31, 2020. The primary outcome was the time to hospital discharge. Secondary outcomes included the incidence of inadequate anesthesia, postoperative pain scores and postoperative neurologic symptoms.ResultsThree hundred and sixty patients were included in the final analysis (bupivacaine n=236, chloroprocaine n=124). The median (IQR) intrathecal dose was 7.5 (7.5, 9) mg and 45 (45, 50) mg in the bupivacaine and chloroprocaine groups respectively. The time (median [IQR]) from spinal anesthesia to hospital discharge was significantly shorter in the chloroprocaine group compared with the bupivacaine group (218 [180, 253] vs. 370 [309, 424] min, P<0.001). There were no significant differences between the groups for secondary outcomes and neither group had a patient report neurologic symptoms.ConclusionWhen utilized in spinal anesthesia for transvaginal cervical cerclage placement, chloroprocaine may reduce the time to discharge while providing comparable anesthesia to that provided by bupivacaine.     

Evaluation of the impact of enhanced recovery after surgery protocol implementation on maternal outcomes following elective cesarean delivery

BackgroundDespite significant improvements in outcomes following non-obstetric surgery with implementation of enhanced recovery after surgery (ERAS) protocols, development of these protocols for cesarean delivery is lacking. We evaluated implementation of an ERAS protocol for patients undergoing elective cesarean delivery, specifically the effect on opioid consumption, pain scores and length of stay as well as complications and re-admissions.MethodsAn ERAS protocol was developed and implemented for women undergoing elective cesarean delivery. The protocol construction included specific evidence-based items applicable to peripartum management and these were grouped into the three major phases of patient care: antepartum, intrapartum and postpartum. A before-and-after study design was used to compare maternal outcomes. To account for confounders between groups, a propensity matched scoring analysis was used. The primary outcome was postpartum opioid use in mg-morphine equivalents (MMEQ).ResultsWe included 357 (n=196 before; n=161 after) women who underwent elective cesarean delivery. A significant difference in opioid consumption (28.4 ± 24.1 vs 46.1 ± 37.0 MMEQ, P <0.001) and in per-day postoperative opioid consumption (10.9 ± 8.7 vs 15.1 ± 10.3 MMEQ, P <0.001), lower peak pain scores (7 [5–9] vs 8 [7–9], P=0.007) and a shorter hospital length of stay (2.5 ± 0.5 vs 2.9 ± 1.2 days, P <0.001) were found after the introduction of the ERAS protocol.ConclusionsImplementation of ERAS protocols for elective cesarean delivery is associated with significant improvements in analgesic and recovery outcomes. These improvements in quality of care suggest ERAS protocols should be considered for elective cesarean delivery.     

A prospective observational study of the change in regional cerebral oxygen saturation during cesarean delivery in women receiving phenylephrine prophylaxis for spinal hypotension

BackgroundSpinal hypotension causes decreased regional cerebral oxygen saturation (ScO₂) in women undergoing cesarean delivery. In this study we aimed to measure the change in ScO₂ using near infrared spectroscopy in women receiving a prophylactic phenylephrine infusion during cesarean delivery under spinal anesthesia.MethodsThis was a prospective, observational cohort study. Fifty-three women had ScO₂ measurements at the following time points: preoperatively, in the supine position with 30° of left lateral tilt; one and five minutes after spinal anesthesia; at the time of skin incision; immediately after delivery; one minute after commencing the oxytocin infusion; at completion of surgery, and one hour after surgery. Spinal anesthesia and a prophylactic phenylephrine infusion were administered according to a standard treatment protocol. Statistical analysis used the Wilcoxon Signed Rank test with Bonferroni’s correction for multiple comparisons.ResultsBlood pressure was maintained within 20% of baseline throughout surgery. The baseline mean (range) ScO₂ was 61.5% (54.0–66.3%). It decreased significantly at all subsequent measurement points. The maximum decrease was five minutes after spinal anesthesia. Thirty-four (64.2%) of the parturients exhibited ScO₂ values <20% of baseline, or a decrease to below an absolute value of 50%. There was no significant correlation between systolic blood pressure and mean ScO₂.ConclusionSpinal anesthesia with phenylephrine infusion during cesarean delivery is associated with a significant decrease in ScO₂ levels, maximal five minutes later. Further studies are required to establish the clinical significance of this finding.     

The impact of gestational age and fetal weight on the risk of failure of spinal anesthesia for cesarean delivery

BackgroundThere are limited data about spinal dosing for cesarean delivery in preterm parturients. We investigated the hypothesis that preterm gestation is associated with an increased incidence of inadequate spinal anesthesia for cesarean delivery compared with term gestation.MethodsWe searched our perioperative database for women who underwent cesarean delivery under spinal or combined spinal-epidural anesthesia with hyperbaric bupivacaine ⩾10.5 mg. The primary outcome was the incidence of inadequate surgical anesthesia needing conversion to general anesthesia or repetition or supplementation of the block. We divided patients into four categories: <28, 28 to <32, 32 to <37 and ⩾37 weeks of gestation. The chi-square test was used to compare failure rates and a multivariable regression analysis was performed to investigate potential confounders of the relationship between gestational age and failure.ResultsA total of 5015 patients (3387 term and 1628 preterm) were included. There were 278 failures (5.5%). The incidence of failure was higher in preterm versus term patients (6.4% vs. 5.1%, P=0.02). Failure rates were 10.8%, 7.7%, 5.3% and 5% for <28, 28 to <32, 32 to <37 and ⩾37 weeks of gestation, respectively. In the multivariable model, low birth weight (P<0.0001), gestational age (P=0.03), ethnicity (P=0.02) and use of combined spinal-epidural anesthesia (P<0.0001) were significantly associated with failure.ConclusionsAt standard spinal doses of hyperbaric bupivacaine used in our practice (⩾10.5 mg), there were higher odds of inadequate surgical anesthesia in preterm parturients. When adjusting for potential confounders, low birth weight was the main factor associated with failure.     

Pencil-point needle bevel direction influences ED50 of isobaric ropivacaine with fentanyl in spinal anesthesia for cesarean delivery: a prospective,double-blind sequential allocation study

BackgroundThere is little evidence on the influence of bevel direction of a pencil-point needle on the median effective dose (ED50) of isobaric ropivacaine and fentanyl in spinal anesthesia for cesarean delivery.MethodsIn this prospective, double-blind, sequential allocation study, 82 parturients scheduled for elective cesarean delivery under combined spinal-epidural anesthesia were included. We sought to determine the median effective dose of intrathecal 0.75% isobaric ropivacaine plus fentanyl 15 μg with two different bevel directions of a 26-gauge Whitacre needle using up-down sequential allocation. Parturients were randomly allocated to either Group Ce (needle aperture oriented in a cephalad direction) or Group Ca (aperture directed caudally). The initial dose was 0.75% ropivacaine 11.25 mg plus fentanyl 15 μg in both groups. Each dose was classified as effective if, after 15 min and during the next 60 min, there was inability to appreciate pin-prick as sharp at T4, a visual analogue pain score <2 and no requirement for an epidural rescue bolus.ResultsEighty patients were included in the analysis. The ED50 in group Ca was significantly higher (13.09 mg, 95% CI 12.19–14.00) than in group Ce (10.10 mg, 95% CI 9.54–10.65, P <0.001).ConclusionThe orientation of the distal aperture of a 26-gauge Whitacre needle during induction of spinal anesthesia for cesarean delivery influences the ED50 of 0.75% ropivacaine.     

Anesthetic technique for cesarean delivery and neonatal acid–base status: a retrospective database analysis

IntroductionA previous meta-analysis reported lower umbilical artery pH with spinal anesthesia for cesarean delivery compared to general or epidural anesthesia. Ephedrine was used in the majority of studies. The objective of this study was to evaluate the effect of anesthetic technique on neonatal acid–base status now that phenylephrine has replaced ephedrine in our institution.MethodsWe retrospectively reviewed our database to identify patients who underwent cesarean delivery and had umbilical artery pH available. We decided a priori to test separately cases where cesarean delivery was performed emergently (category I and II) or non-emergently (category III and IV). Multivariable models were constructed to detect significant predictors of lower umbilical artery pH.ResultsOne thousand sixty-four cases were included (647 emergent, 417 non emergent). In emergent cesarean delivery, anesthesia type was a significant predictor of lower umbilical artery pH (P <0.0001) with the pairwise comparisons showing lower neonatal umbilical artery pH [mean (95% CI)] with general anesthesia [7.16 (7.13, 7.19)] compared with spinal anesthesia [7.24 (7.22, 7.25)] and epidural anesthesia [7.23 (7.21, 7.24)], with no difference between spinal and epidural anesthesia. When excluding cases where general anesthesia was chosen due to insufficient time to place a neuraxial block or dose an existing epidural catheter, anesthesia type was not a predictor of lower umbilical artery pH. Anesthetic technique was not a predictor of lower umbilical artery pH in non-emergent cases.ConclusionsSpinal anesthesia was not associated with lower umbilical artery pH compared to other types of anesthesia. This might be due to the use of phenylephrine in our practice.