The Effect of Posture and Baricity on the Spread of Intrathecal Bupivacaine for Elective Cesarean Delivery

Randomized Double-Blind Study of the Effect of Injectate Temperature on Intrathecal Bupivacaine Dose Requirement in Spinal Anesthesia for Cesarean Delivery

BACKGROUND

Increasing the temperature of intrathecal local anesthetics has been shown to increase the speed of onset and block height of spinal anesthesia. However, how this influences dose requirement has not been fully quantified. The aim of this study was to determine and compare the effective dose for anesthesia for cesarean delivery in 50% of patients (ED50) of intrathecal bupivacaine given at temperatures of 37 °C (body temperature) or 24 °C (room temperature).

METHODS

Eighty healthy parturients having elective cesarean delivery under combined spinal-epidural anesthesia were randomly assigned to receive intrathecal hyperbaric bupivacaine stored at 37 °C (body temperature group) or 24 °C (room temperature group). The first subject in each group received a bupivacaine dose of 10 mg. The dose for each subsequent subject in each group was varied with an increment or decrement of 1 mg based on the response (effective or noneffective) of the previous subject. Patients for whom the dose was noneffective received epidural supplementation after data collection with lidocaine 2% as required until anesthesia was sufficient for surgery. Values for ED50 were calculated using modified up-down sequential analysis with probit analysis applied as a backup sensitivity analysis. These values were compared and the relative mean potency was calculated.

RESULTS

The ED50 (mean [95% confidence interval, CI]) of intrathecal hyperbaric bupivacaine was lower in the body temperature group (6.7 [5.7-7.6] mg) compared with the room temperature group (8.1 [7.7-8.6] mg) (P < .05). The relative potency ratio for intrathecal bupivacaine for the room temperature group versus the body temperature group was 0.84 (95% CI, 0.77-0.93).

CONCLUSIONS

Warming hyperbaric bupivacaine to body temperature reduced the dose requirement for spinal anesthesia for cesarean delivery by approximately 16% (95% CI, 7%-23%).

Effects of buoyancy on the dispersion of drugs released intrathecally in the spinal canal

This paper investigates the transport of drugs delivered by direct injection into the cerebrospinal fluid (CSF) that fills the intrathecal space surrounding the spinal cord. Because of the small drug diffusivity, the dispersion of neutrally buoyant drugs has been shown in previous work to rely mainly on the mean Lagrangian flow associated with the CSF oscillatory motion. Attention is given here to effects of buoyancy, arising when the drug density differs from the CSF density. For the typical density differences found in applications, the associated Richardson number is shown to be of order unity, so that the Lagrangian drift includes a buoyancy-induced component that depends on the spatial distribution of the drug, resulting in a slowly evolving cycle-averaged flow problem that can be analysed with two-time scale methods. The asymptotic analysis leads to a nonlinear integro-differential equation for the spatiotemporal solute evolution that describes accurately drug dispersion at a fraction of the cost involved in direct numerical simulations of the oscillatory flow. The model equation is used to predict drug dispersion of positively and negatively buoyant drugs in an anatomically correct spinal canal, with separate attention given to drug delivery via bolus injection and constant infusion.

Spinal Anaesthesia Using Hypobaric Drugs: A Review of Current Evidence

Spinal anesthesia is one of the most widely used techniques in modern anesthesia practice. It involves the injection of local anesthetic drugs into the cerebrospinal fluid (CSF) within the subarachnoid space. The choice of drug, its concentration, and baricity play a crucial role in determining the characteristics of the spinal block and has evolved over the years with continuous advancements in drug formulations and administration methods. Spinal anesthesia with hypobaric drugs represents a valuable technique in the armamentarium of anesthesiologists, offering distinct advantages in terms of targeted action, reduced systemic toxicity, and enhanced hemodynamic stability. This review aims to scan the characteristics of hypobaric drugs, factors influencing their spread within the spinal canal, challenges associated with their use, clinical applications in various surgical scenarios, and potential implications for patient outcomes and healthcare practice. PubMed and Google Scholar databases were searched for relevant articles and a total of 23 relevant articles were selected for the review based on inclusion and exclusion criteria. Hypobaric drugs have many advantages in high-risk morbidly ill patients for some select surgical procedures and daycare surgeries. The concentration and volume of hypobaric drugs need to be selected according to the extensiveness of the surgery and the desired block can be achieved by giving spinal injection in specific positions. The dynamic field of anesthesiology encompasses the integration of emerging technologies and evidence-based practices, which will contribute to further refining the safety and efficacy of spinal anesthesia with hypobaric drugs.

Mepivacaine Versus Bupivacaine in Adult Surgical Patients: A Meta-analysis, Trial Sequential Analysis of Randomized Controlled Trials

PURPOSE

Evidence supporting the choice between mepivacaine and bupivacaine is inconclusive. This meta-analysis aims to determine whether mepivacaine can reach a similar effect to bupivacaine after surgeries.

DESIGN

A meta-analysis, trial sequential analysis of randomized controlled trials (RCTs).

METHODS

RCTs were identified in PubMed, EMBASE (Ovid), Medline (Ovid), and Cochrane Library using a controlled vocabulary (MeSH) and keywords. There were no date and language restrictions. We strictly included RCTs comparing mepivacaine with bupivacaine. The primary outcome was motor function recovery time. Secondary outcomes included postoperative analgesic requirement, transient neurologic symptoms (TNS), pain score at 24 hours, length of stay (LOS), duration of analgesia, complications, and patient satisfaction. A trial sequential analysis (TSA) was performed for motor function recovery time, postoperative analgesic requirement, and TNS.

FINDINGS

Seven RCTs with a total of 672 patients were included. Return of motor function was quicker in patients who received mepivacaine than in those who received bupivacaine (weighted mean differences [WMD] = -2.23 minutes; 95% confidence intervals [CI], -3.58 to -0.88; P = .02; I² = 97.08%; TSA adjusted CI -17.52 to -10.9). Postoperative analgesic requirement was significantly more with mepivacaine (risk ratio [RR] = 3.23; 95% CI, 1.37-7.62; P = .01; I² = 55.11%; TSA adjusted CI 5.73-63.27). Duration of analgesia (WMD = -8.83 hours; 95% CI, -11.75 to -7.90; P < .001; I² = 0%) and LOS (WMD = -3.95 hours; 95% CI, -4.83 to -3.07; P < .001; I² = 0%) in group mepivacaine was significantly shorter compared with bupivacaine. There were no differences for TNS (RR = 3.90; 95% CI, 0.94-16.22; P = .062; I² = 72.23%), postoperative pain score (standard mean differences [SMD] = 0; 95% CI, -0.10 to 0.10; P = .972; I² = 0%), complications (RR = 1; 95% CI, 0.70-1.43; P = .998; I² = 0%), and satisfaction (RR = 0.97; 95% CI, 0.85-1.11; P = .40; I² = 45%) between bupivacaine and mepivacaine.

CONCLUSIONS

Mepivacaine appears to yield a faster return of motor function and shorter LOS compared with bupivacaine. and may be more popular in short-stay and outpatient surgery. However, the results of TSA indicate that more high-quality trials are needed to confirm the true effects.

Buoyancy-modulated Lagrangian drift in wavy-walled vertical channels as a model problem to understand drug dispersion in the spinal canal

This paper investigates flow and transport in a slender wavy-walled vertical channel subject to a prescribed oscillatory pressure difference between its ends. When the ratio of the stroke length of the pulsatile flow to the channel wavelength is small, the resulting flow velocity is known to include a slow steady-streaming component resulting from the effect of the convective acceleration. Our study considers the additional effect of gravitational forces in configurations with a non-uniform density distribution. Specific attention is given to the slowly evolving buoyancy-modulated flow emerging after the deposition of a finite amount of solute whose density is different from that of the fluid contained in the channel, a relevant problem in connection with drug dispersion in intrathecal drug delivery (ITDD) processes, involving the injection of the drug into the cerebrospinal fluid that fills the spinal canal. It is shown that when the Richardson number is of order unity, the relevant limit in ITDD applications, the resulting buoyancy-induced velocities are comparable to those of steady streaming. As a consequence, the slow time-averaged Lagrangian motion of the fluid, involving the sum of the Stokes drift and the time-averaged Eulerian velocity, is intimately coupled with the transport of the solute, resulting in a slowly evolving problem that can be treated with two-time-scale methods. The asymptotic development leads to a time-averaged, nonlinear integro-differential transport equation that describes the slow dispersion of the solute, thereby circumventing the need to describe the small concentration fluctuations associated with the fast oscillatory motion. The ideas presented here can find application in developing reduced models for future quantitative analyses of drug dispersion in the spinal canal.

THE EFFECTS OF PATIENT POSITION ON EARLY COMPLICATIONS OF SPINAL ANESTHESIA INDUCTION IN ARTHROSCOPIC KNEE SURGERY

Spinal anesthesia is widely used in different patient positions to create efficient and rapid anesthesia induction in surgical interventions. Early and late complications of spinal anesthesia may vary according to the type of needle, drug dose and concentration, patient weight and height, puncture technique, and position of the patient. This study aimed to prospectively compare early complications of spinal anesthesia between patients in sitting and lateral decubitus positions with motor block onset time and sensory block time to T10 level. Spinal anesthesia was performed in 100 ASA I-II patients aged 18-65 years (group S=48; and group L=52) undergoing arthroscopic knee surgery. Hemodynamic data, early complications, sensory and motor block onset times were recorded. Systolic, diastolic and mean arterial pressures were significantly lower in lateral decubitus position as compared to sitting position after spinal anesthesia induction. Arterial blood pressure values decreased significantly in lateral decubitus position as compared with sitting position. Motor block onset time and sensory block onset time were shorter in lateral decubitus position than in sitting position. Accordingly, sitting position could be suggested during induction of spinal anesthesia because it was associated with less pronounced decrease in blood pressures.

Comparative Study of Effect of Spinal Anesthesia in Sitting and Lateral Positions on the Onset Time of Sensory Block and Hemodynamic Condition in Cesarean Section: A Randomized Clinical Trial

BACKGROUND

Spinal anesthesia is the method of choice for the cesarean section. Hypotension is a common complication of this method.

OBJECTIVES

This study aimed to compare the effect of spinal anesthesia in the sitting and lateral positions on the onset time of sensory block and hemodynamic condition in cesarean sections.

METHODS

In this clinical trial, 106 elective cesarean section candidates under spinal anesthesia were selected and randomly divided into two groups: spinal anesthesia in the sitting position (group S) and the lateral position (group L). The onset time of the sensory block, quality of sensory and motor block, hemodynamic condition, frequency of hypotension, nausea, and vomiting, and the doses of ephedrine and atropine were compared between both groups. Data were analyzed with SPSS version 16 software at a 95% confidence level.

RESULTS

There was no statistically significant difference between the two groups in terms of age. The frequency of hypotension in L and S groups was 24.5% and 57.7%, respectively (P = 0.001), in minute 6 after spinal anesthesia and 5.7% and 36.5%, respectively (P < 0.001), in minute 8 after spinal anesthesia. The mean time to reach the sensory level of T6 was 1.30 ± 0.43 min versus 4.54 ± 2.12 min (P < 0.001), motor block score in minute 5 was 2.98 ± 0.14 versus 2.82 (P = 0.044), and ephedrine dose was 11.5 mg and 16.92 mg in the L and S groups, respectively (P = 0.010). The maximum sensory-motor block and satisfaction of women with spinal anesthesia were significantly higher in the lateral position than in the sitting position (P < 0.05).

CONCLUSIONS

Cesarean sections under spinal anesthesia in the lateral position than in the sitting position lead to a more rapid sensory and motor block, reduced ephedrine consumption, and enhanced satisfaction of women.

Effect of addition of intrathecal magnesium sulphate to 0.5% hyperbaric bupivacaine and 0.5% isobaric levobupivacaine on duration of analgesia in parturients undergoing elective caesarean section: A prospective randomised study

Background and Aims:

Addition of magnesium sulfate to local anesthetics improves the quality of spinal anesthesia for caesarean section. The aim of this study was to compare the effects of intrathecal 0.5% hyperbaric bupivacaine with 75-mg magnesium sulfate (MgSO₄) and 0.5% isobaric levobupivacaine with 75-mg MgSO₄ on the duration of analgesia in parturients undergoing elective caesarean section.

Material and Methods:

This prospective randomized double-blind parallel-group study was conducted in 60 parturients undergoing elective caesarean section who were randomly allocated to Group I or Group II to receive either 2 ml of 0.5% levobupivacaine with 75-mg MgSO₄ or 2 ml of 0.5% hyperbaric bupivacaine with 75-mg MgSO₄ intrathecally. The duration of postoperative analgesia along with sensory and motor block characteristics and hemodynamics were studied.

Results:

The duration of analgesia did not show a significant difference in the two groups (P = 0.175). The sensory onset time was faster in Group I (3.5 ± 1.3 min) as compared to that in Group II (4.8 ± 2 min; P = 0.004). The onset of motor blockade was not different in the two groups (P = 0.265), but there was a significant delay (P = 0.002) in motor recovery in Group II (267 ± 130.6 min) as compared to Group I (225 ± 85.4 min). Hemodynamics were comparable in the two groups.

Conclusion:

Intrathecal levobupivacaine with MgSO₄ produces a similar duration of postoperative analgesia as compared to hyperbaric bupivacaine with MgSO₄. Early motor recovery allowing early ambulation postoperatively makes isobaric levobupivacaine with MgSO₄ a good alternative for caesarean sections.

The effect of baricity of intrathecal bupivacaine for elective cesarean delivery on maternal cardiac output: a randomized study

BACKGROUND

Hemodynamic instability during spinal anesthesia for cesarean delivery is associated with adverse maternal and fetal outcomes. Plain and hyperbaric bupivacaine are commonly used for cesarean delivery, however, their distinctive pharmacologic properties may affect maternal hemodynamic profiles differently. The aim of this study was to compare hemodynamic profiles using a suprasternal Doppler cardiac output (CO) monitor in healthy term parturients randomized to receive plain or hyperbaric bupivacaine for cesarean delivery.

METHODS

One hundred-and-sixty-eight healthy parturients scheduled for elective cesarean delivery were randomly assigned to receive 10.9 mg of intrathecal 0.5% plain or hyperbaric bupivacaine, both with 0.2 mg morphine. The primary outcome was CO change after spinal anesthesia. Secondary outcomes were the incidence of hypotension, vasopressor use, and conversion to general anesthesia.

RESULTS

The mean (±SD) CO at baseline, 1 min and 5 min after spinal anesthesia, and after placental delivery was 4.6 ± 1.2, 5.4 ± 1.3, 5.1 ± 1.4, and 6.4 ± 1.7 L/min in the plain bupivacaine, and 4.5 ± 1.1, 5.2 ± 1.3, 4.9 ± 1.3, and 6.2 ± 1.9 L/min in the hyperbaric bupivacaine group. There were no significant differences in CO, mean arterial pressure, or systemic vascular resistance. Incidences of hypotension, vasopressor and supplemental analgesic use, and conversion to general anesthesia, were not different between groups.

CONCLUSIONS

Cardiac output changes after plain or hyperbaric bupivacaine were not different in term parturients undergoing spinal anesthesia for cesarean delivery. Further studies comparing block quality and the rate of conversion to general anesthesia are required.

Randomised Control Trial Comparing Plain Levobupivacaine and Ropivacaine with Hyperbaric Bupivacaine in Caesarean Deliveries

Objective

The study compared spinal block characteristics of equipotent doses of plain 0.5% levobupivacaine, plain 0.75% ropivacaine and hyperbaric 0.5% bupivacaine for elective caesarean (CS) delivery.

Methods

A total of 100 parturient women undergoing elective CS under spinal anaesthesia were enrolled for the study. The parturients were randomly assigned to receive one of the following in a subarachnoid block: hyperbaric 0.5% bupivacaine 10 mg (group B), plain 0.5% levobupivacaine 10 mg (group L), or plain 0.5% ropivacaine 15 mg (group R).

Results

Motor block duration [groups B, LB, R: 143.78 (30.43) minutes, 139.31 (33.38) minutes, 137.32 (27.39) minutes, respectively; P=0.80], sensory block duration [groups B, LB, R: 122.87 (34.93) minutes, 113.03 (39.24) minutes, 125.58 (24.93) minutes, respectively; p=0.30] and first analgesic request time [groups B, LB, R: 136.87 (28.70) minutes, 133.59 (27.30) minutes, 144.19 (32.09) minutes, respectively; p=0.35] were statistically comparable. The groups were statistically comparable for sensory block onset time [T6 block; groups B, LB, R: 4.62 (2.80) minutes, 4.93 (2.63) minutes, 5.73 (3.00) minutes, respectively; p=0.29] but motor block onset time was statistically prolonged for group R as compared to group B [Bromage 3 block; group B, LB, R: 5.93 (3.41) minutes, 9.00 (4.00) minutes, 10.16 (5.66) minutes, respectively; p=0.001]. No statistically significant differences were seen in sensory and motor block recovery times, haemodynamic parameters or side-effects.

Conclusion

The anaesthesia from a spinal block with 10 mg plain levobupivacaine or 15 mg plain ropivacaine is comparable to the anaesthetic effect of 10 mg hyperbaric bupivacaine in elective caesarean deliveries.

The effects of isobaric and hyperbaric bupivacaine on maternal hemodynamic changes post spinal anesthesia for elective cesarean delivery: A prospective cohort study

BACKGROUND

Spinal anesthesia is a form of regional anesthesia frequently used in various lower abdominal, orthopedic, obstetric operations such as a cesarean delivery. The most common local anesthetic used for spinal anesthesia in obstetric and non-obstetric surgery is bupivacaine which can be utilized as an isobaric or hyperbaric solution, producing differences in maternal hemodynamic changes. Against this backdrop, the study aims to compare the effects of isobaric and hyperbaric bupivacaine on maternal hemodynamic alterations after administering spinal anesthesia for elective cesarean delivery at Gandhi Memorial Hospital, Addis Ababa, Ethiopia.

METHODS

A hospital-based prospective cohort study design was employed for the period December 1, 2017 to January 30, 2018. A total of 100 parturient were involved, with one group exposed to isobaric bupivacaine and the other to hyperbaric bupivacaine to observe their effects on maternal hemodynamic changes post spinal anesthesia. The participants were selected through systematic random sampling. Data analysis was performed using SPSS (version 20) through descriptive statistic, independent sample t-test, Mann-Whitney U-test, Fisher's exact test, and Chi-square test were used. P values of <0.05 was assumed as statistically significant for all tests.

RESULTS

The incidence of hypotension was found to be greater in isobaric than hyperbaric groups (82% vs. 60% respectively; p = 0.015). No statistical significant differences were found in mean arterial pressure value at baseline, but, statistically significant changes were observed among the groups (p <0.05) at all study timing after spinal anesthesia, except at 30thmin. No statistically significant differences were seen in the mean heart rate variability after spinal anesthesia at all periods, except the 15th minute (p = 0.033). A greater rate of vasopressor was used in the isobaric group as compared to the hyperbaric group (36% vs. 14% respectively; p = 0.011).

CONCLUSION

Baricity is a significant factor in maternal hemodynamic changes in the parturient for elective cesarean section. Isobaric bupivacaine produces greater change in blood pressure and incidence of hypotension and entails a greater vasopressor requirement than hyperbaric bupivacaine after spinal anesthesia for elective cesarean section.

Correlation of Symphysiofundal Height and Abdominal Girth with the Incidence of Hypotension in Cesarean Section Under Spinal Anesthesia using Bupivacaine with Fentanyl as Adjuvant: A Clinical Study

Background and Aims:

A decreased lumbosacral subarachnoid space volume is a major factor in cephalad intrathecal spread of local anesthetic in term parturients due to compressive effect of the gravid uterus. The aim of this study was to assess the relationship of symphysiofundal height (SFH) and abdominal girth (AG) with the incidence of hypotension and the highest level of sensory blockade.

Settings and Design:

This study was a prospective observational study.

Materials and Methods:

Ninety parturients under the American Society of Anesthesiologists physical status class II within the age range of 20–30 years, weighing between 60 and 65 kg, and height between 150 and 155 cm were studied, and the SFH and AG of all parturients had been measured just before spinal anesthesia. Hyperbaric bupivacaine 9 mg with 12.5 μg intrathecal fentanyl was administered for subarachnoid block. The incidence of hypotension and the highest level of sensory block were assessed.

Statistical Analysis:

Correlation analysis (Spearman's rank test) was applied to analyze the data, and P < 0.05 was considered to be statistically significant.

Results:

The incidence of hypotension was higher with increasing SFH (16.9% with SFH of 30–35 cm, 78.37% with SFH of 36–40 cm; correlation coefficient ρ =0.338) and with increasing AG (5.3% with AG between 85 and 89 cm, 35.7% with AG 90–94 cm, 62.8% with AG 95–99 cm; ρ =0.341), and both were statistically significant (P < 0.001). There was a statistically significant correlation between increasing SFH and maximum sensory block achieved (ρ =0.157, P < 0.001). There was increased level of sensory blockade with increased AG but was not statistically significant (ρ =0.011, P = 0.32).

Conclusion:

In term parturients undergoing cesarean section under spinal anesthesia, the SFH has a significant positive correlation with the incidence of hypotension and ascent of spinal anesthesia. AG also has a positive correlation with the incidence of hypotension but is not significant with the ascent of spinal anesthesia.

Successful spinal anaesthesia for caesarean section in a patient with Marfan syndrome complicated by dural ectasia

Marfan syndrome is a connective tissue disorder that may be complicated during pregnancy by aortic dissection. Caesarean section may be selected to avoid the haemodynamic challenges of vaginal birth. The common occurrence of dural ectasia in patients with Marfan syndrome is known to be associated with failed neuraxial anaesthesia. This report describes the administration of spinal anaesthesia to a woman with Marfan syndrome, and discusses why a hypobaric bupivacaine and opioid mixture, warmed to 37°C and injected intrathecally with the patient seated, produced successful surgical anaesthesia.

Level of sensory block after spinal anesthesia as a predictor of hypotension in parturient

When the sensory block level (SBL) is ≥T5 or T4, a high incidence of hypotension occurs in parturients after spinal anesthesia. A rapidly ascending SBL is another risk factor for spinal anesthesia-induced hypotension. However, the relationship between the ascension rate of the SBL and spinal anesthesia-induced hypotension remains unclear.After placement in the left lateral position, combined epidural-spinal anesthesia was performed on 140 parturients undergoing caesarean section using the following procedure: no volume preloading, injection site of L3-4 or L4-5, injection rate of 0.1 mL/sec, and administration of 10 mg of 0.5% hyperbaric bupivacaine. A receiver-operating characteristic curve was built to estimate the accuracy of the SBL ascension rate in detecting spinal anesthesia-induced hypotension.The mean time interval from spinal injection to placement in the supine position was 136 ± 10 seconds in all anesthesia procedures. The earliest and most complete records of the SBL started from the 3rd minute after spinal injection. The threshold spread rate corresponding to the highest accuracy for occurrence of hypotension was an SBL of ≥T8 at the 3rd minute after spinal injection, with 82% and 88% sensitivity and specificity, respectively.The ascension rate of an SBL of ≥T8 at the 3rd minute after spinal injection is as a predictor of hypotension in parturients.

Comparison of 1- and 2-Minute Sitting Positions Versus Immediately Lying Down on Hemodynamic Variables After Spinal Anesthesia with Hyperbaric Bupivacaine in Elective Cesarean Section

BACKGROUND

Hypotension is one of the most common complications of spinal anesthesia in parturients undergoing cesarean section. In this regard, the patient's position may affect the incidence of hypotension.

OBJECTIVES

In this clinical trial, we evaluated the effects of 1- and 2-minute sitting positions versus immediately lying down after spinal anesthesia on hypotension and vasopressor requirements.

METHODS

A total of 72 parturients, scheduled for cesarean section under spinal anesthesia, were randomly divided into 3 groups (24 subjects per group). Groups S1 and S2 remained in a sitting position for 1 and 2 minutes after the induction of spinal anesthesia, respectively, while group T was immediately placed in a lying position. Systolic, diastolic, and mean arterial blood pressure, as well as heart rate, was recorded at 1, 2, 3, and 5 minutes after anesthesia induction, every 5 minutes during the first 30 minutes of surgery, and then every 10 minutes until the end of surgery. P-value less than 0.05 was considered statistically significant.

RESULTS

The overall frequency of hypotension was 50 (69%) cases during surgery; the reported frequency was higher in group T in comparison with group S2 (P = 0.003). The frequency of hypotension before delivery (the first 5 minutes after spinal anesthesia) was 40 (55%) cases, with a higher frequency reported in group T (20, 83%), compared to groups S1 (12, 50%) and S2 (8, 33%) (P = 0.03 and P = 0.001, respectively). The ephedrine requirement in group T (11.73 ± 7.16 mg) was higher than the other two groups (8.69 ± 7.57 and 7.82±7.95 mg in groups S1 and S2, respectively); nevertheless, the difference was not statistically significant (P = 0.19). Moreover, the difference in time to achieve T6 sensory level was only significant between group T (3.25 ± 1.1 minutes) and group S2 (4.73 ± 1.73 minutes) (P = 0.03).

CONCLUSIONS

The present study showed that 1- or 2-minute sitting position after spinal anesthesia with 2.5 cc of hyperbaric bupivacaine in elective cesarean section results in more hemodynamic stability, compared with immediately lying down.

Baricity of Bupivacaine on Maternal Hemodynamics after Spinal Anesthesia for Cesarean Section: A Randomized Controlled Trial

BACKGROUND

After spinal anesthesia, patients undergoing cesarean section are more likely to develop hemodynamic changes. The baricity of local anesthetic has an important role on spinal blockade effects. The aim of this study was to compare the isobar and hyperbaric bupivacaine 0.5% plus fentanyl on maternal hemodynamics after spinal anesthesia for C/S.

METHODS

In this double-blind study, 84 healthy pregnant women undergoing C/S using bupivacaine 0.5% isobar (study group, n=42) or hyperbaric (control group, n=42) for spinal anesthesia were scheduled. The study was conducted from 21 April 2014 to 21 November 2014 at Al-Zahra Hospital, Tabriz, Iran. Parameters such as maternal hemodynamics, block characteristics, side effects, and neonatal Apgar scores were recorded. Data were analyzed using the SPSS software by performing chi-square test, Fisher's exact test, one-way ANOVA, Mann-Whitney U-test, and student's t test.

RESULTS

The incidence of hypotension in the isobar group was lower than the hyperbaric group, although it was not statistically significant (40.47% vs. 61.9%, P=0.08). The duration of hypotension was shorter in the study group (1.6±7.8 min vs. 7.4±12.5 min, P=0.004). The dose of ephedrine was lower in the study group (2.4±6.6 mg vs. 5.3±10.7 mg, P=0.006). The main maternal side effect is sustained hypotension that was seen in 0 patients of the isobar and 7 (16.66%) of hyperbaric groups (P=0.006). None of the neonates had Apgar score≤7 at 5 min of delivery (P=1.0). Sensory and motor block duration was shorter in the study group (P=0.01).

CONCLUSION

Isobaric bupivacaine is associated with more hemodynamic stability and shorter sensory and motor blockade in mothers under spinal anesthesia for C/S. Trial Registration Number: IRCT201401287013N7.

A randomized controlled study comparing intrathecal hyperbaric bupivacaine-fentanyl mixture and isobaric bupivacaine-fentanyl mixture in common urological procedures

Background and Aims:

Bupivacaine is available in isobaric and hyperbaric forms for intrathecal use and opioids are used as additives to modify their effects. The aim of this study was to compare the efficacy and haemodynamic effect of intrathecal isobaric bupivacaine-fentanyl mixture and hyperbaric bupivacaine-fentanyl mixture in common urological procedures.

Methods:

One hundred American Society of Anesthesiologists physical status 1 and 2 patients undergoing urological procedures were randomized into two groups. Group 1 received 3 ml of 0.5% isobaric bupivacaine with 25 μg fentanyl while Group 2 received 3 ml of 0.5% hyperbaric bupivacaine with 25 μg fentanyl. The parameters measured include heart rate, blood pressure, respiratory rate, onset and duration of motor and sensory blockade. Student's unpaired t-test and the χ² test were used to analyse the results, using the SPSS version 11.5 software.

Results:

The haemodynamic stability was better with isobaric bupivacaine fentanyl mixture (Group 1) than with hyperbaric bupivacaine fentanyl mixture (Group 2). The mean onset time in Group 1 for both sensory block (4 min) and motor block (5 min) was longer compared with Group 2. The duration of sensory block (127.8 ± 38.64 min) and motor block (170.4 ± 27.8 min) was less with isobaric bupivacaine group compared with hyperbaric bupivacaine group (sensory blockade 185.4 ± 16.08 min and motor blockade 201.6 ± 14.28 min). Seventy percent of patients in Group 2 had maximum sensory block level of T₆ whereas it was 53% in Group 1. More patients in Group 1 required sedation compared to Group 2.

Conclusion:

Isobaric bupivacaine fentanyl mixture was found to provide adequate anaesthesia with minimal incidence of haemodynamic instability.

Differences in lumbar dural sac dimension in supine and lateral positions in late pregnancy: a magnetic resonance imaging study

BACKGROUND

This study was designed to quantitatively investigate differences in lumbar dural sac dimensions between the lateral and supine positions in late pregnancy.

METHODS

Ten healthy volunteers with singleton pregnancies at 28-39weeks of gestation were included. Magnetic resonance imaging was performed in random order while subjects were in the left lateral and supine positions. Lumbosacral axial scans were obtained at the L1-2, L2-3, L3-4, L4-5 and L5-S1 intervertebral disc levels. The axial section area, anteroposterior maximum diameter and transversal maximum diameter of the dural sac were measured and differences between these parameters in the lateral and supine positions were compared.

RESULTS

The axial section areas of the dural sac at L1-2 (P<0.001), L2-3 (P=0.001), L3-4 (P<0.001) and L4-5 (P=0.005) and the transversal maximum diameter of the dural sac at L1-2 (P<0.001), L2-3 (P<0.001), L3-4 (P<0.001) and L4-5 (P=0.001) were greater in the lateral position compared with the supine position. The anteroposterior maximum diameter of the dural sac at L4-5 was greater in the lateral position compared with the supine position (P=0.019) but there were no significant differences at other levels. The magnitude of the differences in axial section area and transverse maximal diameter were similar among the levels studied.

CONCLUSIONS

The axial section area and the transversal maximum diameter of the dural sac in the lumbar area are reduced in the supine compared with the lateral position in late pregnancy.

Comparison of maternal and fetal outcomes among patients undergoing cesarean section under general and spinal anesthesia: a randomized clinical trial

CONTEXT AND OBJECTIVE

As the rates of cesarean births have increased, the type of cesarean anesthesia has gained importance. Here, we aimed to compare the effects of general and spinal anesthesia on maternal and fetal outcomes in term singleton cases undergoing elective cesarean section.

DESIGN AND SETTING

Prospective randomized controlled clinical trial in a tertiary-level public hospital.

METHODS

Our study was conducted on 100 patients who underwent cesarean section due to elective indications. The patients were randomly divided into general anesthesia (n = 50) and spinal anesthesia (n = 50) groups. The maternal pre and postoperative hematological results, intra and postoperative hemodynamic parameters and perinatal results were compared between the groups.

RESULTS

Mean bowel sounds (P = 0.036) and gas discharge time (P = 0.049) were significantly greater and 24th hour hemoglobin difference values (P = 0.001) were higher in the general anesthesia group. The mean hematocrit and hemoglobin values at the 24th hour (P = 0.004 and P < 0.001, respectively), urine volume at the first postoperative hour (P < 0.001) and median Apgar score at the first minute (P < 0.0005) were significantly higher, and the time that elapsed until the first requirement for analgesia was significantly longer (P = 0.042), in the spinal anesthesia group.

CONCLUSION

In elective cases, spinal anesthesia is superior to general anesthesia in terms of postoperative comfort. In pregnancies with a risk of fetal distress, it would be appropriate to prefer spinal anesthesia by taking the first minute Apgar score into account.

A randomized clinical study comparing spinal anesthesia with isobaric levobupivacaine with fentanyl and hyperbaric bupivacaine with fentanyl in elective cesarean sections

BACKGROUND

To date, racemic bupivacaine is the most popular local anesthetic for spinal anesthesia in parturients undergoing elective cesarean delivery. With the introduction of levobupivacaine as pure S (-) enantiomer of bupivacaine which offers advantages of lower cardiotoxicity and neurotoxicity and shorter motor block duration, its use has widely increased in India. However, very few studies have been conducted about its efficacy in obstetric anesthesia. Thus, this study was undertaken to compare the sensorial, motor block levels, and side-effects of equal doses of hyperbaric bupivacaine and levobupivacaine with intrathecal fentanyl addition in elective cesarean cases.

MATERIALS AND METHODS

After approval of College Ethical Committee, 30 parturient with American Society of Anesthesiologists I-II undergoing elective cesarean section were enrolled for study with their informed consent. They were randomly divided equally to either Group BF receiving 10 mg (2 ml) hyperbaric bupivacaine and 25 mcg (0.5 ml) fentanyl, or Group LF receiving 10 mg (2 ml) isobaric levobupivacaine and 25 mcg (0.5 ml) fentanyl. Sensory and motor block characteristics of the groups were assessed with pinprick, cold swab, and Bromage scale; observed hemodynamic changes and side-effects were recorded. Effects on the neonate were observed by APGAR score at 1 and 5 min and umbilical cord blood gas analysis.

RESULTS

Hemodynamic parameters like mean arterial pressure of Group BF were found to be lower. Group BF exhibited maximum motor block level whereas in Group LF, max sensorial block level and postoperative visual analog scale scores were higher. Umbilical blood gas pCO2 was slightly higher, and pO2 was marginally lower in Group BF. Onset of motor block time, time to max motor block, time to T10 sensorial block, reversal of two dermatome, the first analgesic need were similar in both groups.

CONCLUSION

Intrathecal isobaric levobupivacaine-fentanyl combination is a good alternative to hyperbaric bupivacaine-fentanyl combination in cesarean surgery as it is less effective in motor block, it maintains hemodynamic stability at higher sensorial block levels.

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

BACKGROUND

There 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.

METHODS

In 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 15μg 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 11.25mg plus fentanyl 15μg in both groups. Each dose was classified as effective if, after 15min and during the next 60min, 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.

RESULTS

Eighty patients were included in the analysis. The ED50 in group Ca was significantly higher (13.09mg, 95% CI 12.19-14.00) than in group Ce (10.10mg, 95% CI 9.54-10.65, P <0.001).

CONCLUSION

The 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.

Maternal position and development of hypotension in patients undergoing cesarean section under combined spinal-epidural anesthesia of intrathecal hyperbaric ropivacaine

BACKGROUND

Spinal anesthesia (SA) is usually associated with hypotension in pregnant women. We sought to assess the influence of various maternal positions on SA-induced hypotension

MATERIAL/METHODS

The study population comprised 99 women at full-term gestation scheduled for elective cesarean section. They were randomized into 3 equal groups: the LL group, in which the patient was placed in the full left-lateral position until the start of surgery with the Whitacre needle bevel oriented laterally; the LS group, in which the patient was placed in the full left-lateral position initially and then shifted to the left-tilt supine position with the needle bevel oriented laterally; and the CS group, in which the patient was initially placed in the full left-lateral position and then shifted to the left-tilt supine position with the needle oriented in the cephalad direction.

RESULTS

The incidences of hypotension in the LL, LS, and CS groups were 9.7%, 54.8%, and 56.3%, respectively. Ephedrine requirements were lower in the LL group than in the LS group (P<0.01).

CONCLUSIONS

The maternal position during the induction of anesthesia played an important role in the development of hypotension during cesarean delivery.

Comparison of Maternal and Neonatal Effects of Combined Spinal Epidural Anaesthesia in Either the Sitting or Lateral Position During Elective Cesarean Section

OBJECTIVE

Our goal was to demonstrate which position would be hemodynamically and technically better by comparing the effects of combined spinal epidural (CSE) in the sitting or lateral decubitus position for elective cesarean deliveries on maternal and neonatal parameters and ephedrine requirement.

METHODS

Sixty parturients were randomly assigned into two groups to perform CSE in the sitting (Group I, n=30) or right lateral decubitus position (Group II, n=30) using hyperbaric 10 mg bupivacaine and 20 μg fentanyl. Mean arterial pressure (MAP), heart rate (HR), and characteristics of sensory and motor block were recorded from intrathecal drug administration until the end of surgery. Ephedrine and 1(st) analgesic requirement, number of attempts to perform CSE, incidence of paresthesia during spinal needle insertion, and Apgar scores were recorded.

RESULTS

Ephedrine requirements and HR changes were similar in both groups. However, MAP values at 45 min in Group II were significantly less than in Group I. Maximum sensory block levels in Group II were significantly higher than in Group I. Despite similar motor block recovery times in both groups, regression times of sensory block and 1st analgesic requirement in Group II were significantly longer than in Group I. Incidence of paresthesia due to spinal needle (3.3% versus 20% in Groups I and II, respectively) and number of attempts to perform CSE (26.7% versus 60% in Groups I and II, respectively) were significantly higher in Group II. Apgar scores were similar in both groups.

CONCLUSION

Performing CSE in the sitting position would be safer and easier because higher and earlier onset of sensory block, and a greater number attempts at epidural insertion and paresthesia develop to spinal needle insertion in the right lateral position.

A comparison of the haemodynamic effects of lateral and sitting positions during induction of spinal anaesthesia for caesarean section

BACKGROUND

Hypotension during spinal anaesthesia occurs commonly in parturients. By influencing spread of local anaesthetic, maternal position may affect the speed of onset of sensory block and thus the haemodynamic effects. The aim of this study was to determine whether inducing spinal anaesthesia for caesarean section using plain bupivacaine in the lateral position would result in less hypotension compared with the sitting position.

METHODS

One hundred American Society of Anesthesiologists physical status I and II patients undergoing elective caesarean section were randomised to receive spinal anaesthesia in the lateral position (Group L) or the sitting position (Group S). Using the L3-4 interspace, patients received intrathecal plain bupivacaine, 10mg or 12 mg according to their height, after which they were placed immediately in the supine position with left uterine displacement. Maternal blood pressure was measured every minute for 10 min, every three min for 20 min and 5-minutely thereafter. Hypotension was defined as a fall in systolic blood pressure >20% or a value <90 mmHg.

RESULTS

There was no difference in the lowest recorded systolic blood pressure in Group L (99.2±8.9 mmHg) compared with Group S (95.4±12.3 mmHg, P=0.081). However, the lowest recorded mean arterial pressure was greater in Group L (72.9±11.2 mmHg) than in Group S (68.2±9.6 mmHg; P=0.025). The incidence of hypotension was lower in Group L (17/50, 34%) than in Group S (28/50, 56%; P=0.027). Onset of hypotension was similar between groups.

CONCLUSION

Hypotension occurred less frequently when spinal anaesthesia for caesarean using plain bupivacaine was induced with patients in the lateral compared with the sitting position. Values for the lowest recorded mean arterial pressure were greater but values for the lowest recorded systolic blood pressure were similar for patients in the lateral position group.

Combined spinal epidural and epidural volume extension: Interaction of patient position and hyperbaric bupivacaine

BACKGROUND

Previous trials have documented failure of block augmentation with epidural volume extension, when applied after the intrathecal injection of hyperbaric bupivacaine was made in sitting position. However, there is no study comparing the effect of change in patient position during block performance, on the results of epidural volume extension.

MATERIALS AND METHODS

The study was conducted in two parts in American Society of Anesthesiologists physical status I or II parturients scheduled for elective cesarean section under regional anesthesia. In the first part, 28 patients were randomized to one of the two groups, depending on whether epidural volume extension was applied following the block in sitting (group SE) or lateral position (group LE) (n=14 each). In the second part of the study another 28 patients were recruited and randomized to receive the block in sitting (group S) or lateral (group L) position (n=14 each), without epidural volume extension. All patients received combined spinal epidural block using needle-through-needle technique with intrathecal injection of 9 mg hyperbaric bupivacaine (0.5%) and 10 μg fentanyl. Epidural volume extension was performed using 5 ml normal saline in groups SE and LE.

RESULTS

In the first part of the study, the maximum sensory block level was higher in group LE vs. SE (P<0.05). In the second part of the study, no significant difference was seen in the maximum sensory level between group S and group L (P>0.05).

CONCLUSIONS

If epidural volume extension is being applied with intention of rapid extension of sensory block when hyperbaric bupivacaine has been injected intrathecally, the combined spinal epidural block should be performed in lateral position rather than in the sitting position.

Effects of sitting up for five minutes versus immediately lying down after spinal anesthesia for Cesarean delivery on fluid and ephedrine requirement; a randomized trial

BACKGROUND

Patient position after spinal anesthesia has had variable effects on blood pressure and ephedrine requirements. The aim of this study was to determine the effects that sitting the patient up for five minutes after spinal anesthesia would have on intraoperative fluid and ephedrine requirements.

METHODS

The study included 120 women at term gestation who were scheduled for Cesarean delivery under spinal anesthesia. After anesthetic administration, the women were randomized either to sit up for five minutes then lie down (Group S) or to lie down immediately (Group L) to a tilted supine position. A blinded observer recorded sensory block level, systolic blood pressure, heart rate, ephedrine and fluid requirements, adverse events, and time to motor recovery (modified Bromage score of 2).

RESULTS

Group S had a lower intraoperative sensory block height than Group L [T4 (1) vs T2 (1), respectively; P < 0.001]; Group S also required less ephedrine (8% vs 47%, respectively; P < 0.001), received less fluid [709 (59) mL vs 789 (90) mL, respectively; P < 0.001], and experienced less nausea and vomiting (5% vs 22%, respectively; P = 0.014) and shortness of breath (3% vs 28%, respectively; P < 0.001) intraoperatively. In Group S, the odds of requiring ephedrine were 0.09 compared with 0.89 in Group L (odds ratio 0.10). There were no differences in systolic blood pressure (P = 0.127) or heart rate (P = 0.831) over time between groups. Time to a modified Bromage score of 2 was longer in Group S than in Group L [101 (15) min vs 88 (14) min, respectively; P < 0.001].

CONCLUSIONS

Sitting the patient up for five minutes rather than laying the patient down immediately after spinal anesthesia for Cesarean delivery decreased intraoperative sensory block height, ephedrine and fluid requirements, and intraoperative nausea, vomiting, and shortness of breath without affecting systolic blood pressure or the success of the anesthetic. However, the method resulted in delayed postoperative motor recovery.

Does the baricity of bupivacaine influence intrathecal spread in the prolonged sitting position before elective cesarean delivery? A prospective randomized controlled study

BACKGROUND

Difficulties in inserting an epidural catheter while performing combined spinal-epidural anesthesia for cesarean delivery may lead to undue delays between the spinal injection of the local anesthetic mixture and the adoption of the supine position with lateral tilt. We hypothesized that this delay may affect the intrathecal distribution of local anesthetic of different baricities such that hypobaric local anesthetic would lead to a higher sensory block level.

METHODS

Healthy parturients with uncomplicated pregnancies undergoing elective cesarean delivery under combined spinal-epidural anesthesia were enrolled in this prospective double-blind randomized controlled trial. The subjects were allocated to receive hyperbaric (hyperbaric group), isobaric (isobaric group), or hypobaric (hypobaric group) spinal bupivacaine 10 mg. After the spinal injection, the subjects remained in the sitting position for 5 minutes (to simulate difficulty in inserting the epidural catheter) before being helped into the supine lateral tilt position. The primary outcome was the sensory block level during the 25 minutes after the spinal injection. Other end points included motor block score, maternal hypotension, and vasopressor requirements.

RESULTS

Data from 89 patients were analyzed. Patient characteristics were similar in all groups. The median [interquartile range] (95% confidence interval) sensory levels after spinal injection were significantly higher with decreasing baricity: hyperbaric T10 [T11-8] (T10-9), isobaric T9 [T10-7] (T9-7), and hypobaric T6 [T8-4] (T8-5) (P < 0.001, Cuzick trend). All patients in the hypobaric group reached a sensory block level of T4 at 25 minutes after spinal injection compared with 80% of the patients in both the isobaric and hyperbaric groups (P = 0.04; difference 20%, 95% confidence interval of difference 4%-33%). Significantly more patients in the hypobaric group had complete lower limb motor block (Bromage score = 4) (hyperbaric 43%, isobaric 63%, and hypobaric 90%; P < 0.001). The incidences of maternal hypotension and nausea and vomiting were similar among groups, although the ephedrine requirements were significantly increased in the isobaric and hypobaric groups by factors of 1.83 and 3.0, respectively, compared with the hyperbaric group (P < 0.001, Cuzick trend).

CONCLUSIONS

We demonstrated that when parturients undergoing cesarean delivery were maintained in the sitting position for 5 minutes after spinal injection of the local anesthetic, hypobaric bupivacaine resulted in sensory block levels that were higher compared with isobaric and hyperbaric bupivacaine, respectively, during the study period.

Comparative study of fentanyl and morphine in addition to hyperbaric or isobaric bupivacaine in combined spinal anaesthesia for caesarean section

INTRODUCTION

The aim of our study was to compare the effects of isobaric and hyperbaric bupivacaine combined with morphine or fentanyl in patients undergoing caesarean section. We assessed quality and spread of analgesia and anaesthesia, postoperative analgesic requirement and side effects.

MATERIAL AND METHODS

Hundred patients with American Society of Anesthesiologists physical status (ASA) I-II, age 18 to 40 years, were randomized to 4 groups. The intrathecal solutions were isobaric bupivacaine + morphine (group A), isobaric bupivacaine + fentanyl (group B), heavy bupivacaine + + morphine (group C) and heavy bupivacaine + fentanyl (group D). Mean arterial pressure, heart rate, oxygen saturation, ephedrine consumption, analgesic requirement time and additional analgesic needs were recorded.

RESULTS

The 1(st) min value of mean arterial pressure was the lowest one in all groups. Heart rate decreased significantly in group A at the 10(th) min but not in the other groups. The decrease of visual analogue scale (VAS) pain scores began in the groups after the 4(th) postoperative h (p < 0.05) and the VAS value of group B at the 8(th) h was significantly higher than the other groups. The first analgesic requirement time in the postoperative period was longer in patients who had intrathecal morphine than those who had fentanyl. The duration of analgesia with isobaric bupivacaine and morphine was the longest one.

CONCLUSIONS

We concluded that intrathecal morphine provides a long duration of postoperative analgesia but the duration gets longer when it is combined with plain bupivacaine instead of heavy bupivacaine.

Improvement of quality of reporting in randomised controlled trials to prevent hypotension after spinal anaesthesia for caesarean section

Hypotension is a frequent complication of spinal anaesthesia for caesarean section and can threaten the well-being of the unborn child. Numerous randomised controlled trials (RCTs) dealt with measures to prevent hypotension. The aim of this study was to determine the reporting quality of RCTs using the Consolidated Standards of Reporting Trials (CONSORT) statement since low quality can lend false credibility to a study and overestimate the effect of an intervention. We performed a systematic literature search in PubMed to identify relevant RCTs in a pre-CONSORT period (1990-1994) and a post-CONSORT period (2004-2008). A comparative evaluation was done between the two periods, and the trials were assessed for compliance with each of the 22 CONSORT items. A total of 37 RCTs was identified. The CONSORT score increased significantly (p < 0.05) from 66.7% (±12.5%) in the pre-CONSORT period to 87.4% (±6.9%) in the post-CONSORT period. A statistically significant improvement was found for eight items, including randomization, blinding and intention-to-treat analysis. The CONSORT score in the post-CONSORT era was fairly good, also in comparison to other medical fields. In the post-CONSORT era, reporting of important items improved, in particular in the domains that are crucial to avoid bias and to improve internal validity. Use of CONSORT should be encouraged in order to keep or even improve the reporting quality.

The relationship between symphysis-fundal height and intravenous ephedrine dose in spinal anesthesia for elective cesarean section

Background

A decreased lumbosacral subarachnoidal space volume is a major factor in the cephalad intrathecal spread of local anesthetics in term parturients and their subarachnoidal space is decreased due to the compressive effect of huge uteri. Therefore, they show a higher level of sensory block and hypotensive episodes. The purpose of this study is to investigate whether the symphysis-fundal height (SFH) correlates with the highest sensory level and the amount of ephedrine administered under spinal anesthesia.

Methods

Fifty-two uncomplicated parturients who consented to spinal anesthesia for elective cesarean section were studied. The SFH of all parturients had been measured just before the spinal anesthesia administered by one person. Hyperbaric bupivacaine with fentanyl 20 µg, was administered for spinal anesthesia. The amount of 0.5% bupivacaine was adjusted according to the patient's height and weight. The level of sensory block and the amounts of ephedrine to treat hypotension, nausea and vomiting were assessed. Linear regression and correlation analysis were applied to analyze the data.

Results

According to the results of correlation analysis, there was no significant correlation between the level of sensory block and SFH. There were statistically significant positive correlations between the amount of ephedrine administered due to hypotension and SFH.

Conclusions

In term parturients choosing elective cesarean section, the SFH is not correlated with the sensory level of spinal anesthesia, but is correlated with the amount of ephedrine administered during spinal anesthesia.

Definitions of hypotension after spinal anaesthesia for caesarean section: literature search and application to parturients

BACKGROUND

Spinal anaesthesia for caesarean section may cause hypotension, jeopardizing the foetus and its mother. We aimed to identify the spectrum of definitions of hypotension used in the scientific literature. In a second part, we applied these definitions to a prospective cohort in order to evaluate the effect of different definitions on the incidence of hypotension.

METHODS

A systematic literature search in PubMed was performed from 1999 to 2009 with the search terms 'hypotension' and 'caesarean section'. Consecutive parturients undergoing caesarean section under spinal anaesthesia were included in a prospective study.

RESULTS

Sixty-three eligible publications (7120 patients) were retrieved, revealing 15 different definitions of hypotension. A decrease below 80% baseline and the combined definition of a blood pressure below 100 mmHg or a decrease below 80% baseline were the two most frequent definitions, found in 25.4% and 20.6% of the papers, respectively. When applying the spectrum of definitions to a prospective cohort, the incidences of hypotension varied between 7.4% and 74.1%. The incidence increased from 26.7% to 38.5% when using a value below 75% of baseline instead of below 70% of baseline.

CONCLUSION

There is not one accepted definition of hypotension in the scientific literature. The incidence of hypotension varies depending on the chosen definition. Even minor changes of the definition cause major differences in the frequency of hypotension. This makes it difficult to compare studies on interventions to treat/prevent hypotension and probably hampers progress in this area of research.

Influence of positioning on plain levobupivacaine spinal anesthesia in cesarean section

Background. The behaviour of isobaric levobupivacaine in relation to gravity when used in obstetric spinal anesthesia is unclear. Methods. 46 women with ASA physical status 1 undergoing cesarean section were randomly allocated to 2 groups. Spinal anesthesia with 12.5 mg levobupivacaine was performed in the sitting position in all women. Those in the first group were placed in the supine position immediately after the injection, while those in the second group were asked to remain seated for 2 minutes before assuming the supine position. The sensory block level, the onset of sensory and motor blocks, the regression of the sensory block for 2 dermatomes of the sensory block, the first request for analgesics, and the regression of motor block were recorded. Results. No differences in onset times, sensory level, or Bromage score were observed between the two groups. The time of first analgesic request was earlier in the seated group (supine 131 ± 42 min, seated 106 ± 29 min, P = .02). Conclusion. Isobaric levobupivacaine in women at term produces a subarachnoid block the dermatomal level of which does not depend on gravitational forces.

A randomised controlled trial of hyperbaric bupivacaine with opioids, injected as either a mixture or sequentially, for spinal anaesthesia for caesarean section

It is common practice to mix opioids with hyperbaric bupivacaine in a single syringe before intrathecal injection of the mixture. Mixing these drugs may alter the density of the hyperbaric solution, affecting the spread of local anaesthetic and opioid. Forty-eight women having elective caesarean section under spinal anaesthesia were recruited to this double-blind, randomised trial. Group M (n=24) received 2 ml of 0.5% hyperbaric bupivacaine plus morphine 100 microg plus fentanyl 15 microg, mixed in a syringe prior to administration. Group S (n=24) received 2 ml of 0.5% bupivacaine through one syringe, followed by morphine 100 microg plus fentanyl 15 microg through a separate syringe. All patients received patient-controlled intravenous morphine for 24 hours postoperatively. Block characteristics, postoperative pain scores and morphine use were noted. The patients in Group M had higher levels of sensory block to cold than those in Group S (median T2 vs. T3) (P = 0.003). Five patients in Group M and none in Group S had a block to cold > or = T1 (P = 0.02). There was no difference between groups in the incidence of hypotension, need for vasopressor or side-effects. Morphine consumption was significantly higher in group M (13.3 +/- 11.2 vs. 6.2 +/- 7.2 mg, P = 0.015). Mixing of fentanyl and morphine with hyperbaric bupivacaine results in a higher level of sensory block than sequential administration of bupivacaine then opioid and may be associated with higher postoperative opioid requirement.

Spread of spinal anesthesia in patients having perianal surgery in the jackknife position: effects of baricity of 0.5% bupivacaine and positioning during and after induction of spinal anesthesia

STUDY OBJECTIVE

To compare the influence of baricity and patient positioning during onset of subarachnoid block in patients placed in the prone, jackknife position with head-down tilt of 15 degrees .

DESIGN

Randomized study.

SETTING

Operating room of Tonami General Hospital.

PATIENTS

180 ASA physical I and II patients (134 men and 46 women), aged 18 to 54 years, scheduled for elective perianal surgery.

INTERVENTIONS

Patients were randomly divided into 6 groups (n = 30 each) based on baricity (hyperbaric or isobaric) of 0.5% bupivacaine (5 mg) and duration of the sitting position (two, 5, or 10 min) after injection.

MEASUREMENTS

Sensory block levels were examined by pinprick at 0, 5, 10, 20, and 60 minutes after jackknife positioning. Systolic blood pressure and heart rate were also recorded.

MAIN RESULTS

After jackknife positioning, sensory block levels progressively increased until 15 or 20 minutes in all groups. Regardless of baricity of bupivacaine, sensory block levels were higher at 10 through 60 minutes in the two-minute sitting groups than in the 5-minute or 10-minute sitting groups (P < 0.01 and P < 0.01, respectively), and in the 5-minute sitting groups than in the 10-minute sitting groups (P < 0.05). The mean highest sensory block levels were T5, T9, and T11 in the two-minute, 5-minute, and 10-minute sitting groups, respectively.

CONCLUSION

Patient positioning, not baricity of bupivacaine, significantly affected the cephalad spread of spinal anesthesia, and a 10-minute period in the sitting position limits the maximum cephalad spread to T11.

Single-shot spinal anaesthesia, combined spinal-epidural and epidural volume extension for elective caesarean section: a randomized comparison

BACKGROUND

Single-shot spinal and combined spinal-epidural block, with or without epidural volume extension, can be used for caesarean section. There is no trial comparing their block characteristics and adverse effects under identical conditions.

METHODS

60 ASA I or II parturients with gestational age 37 weeks or more, scheduled for elective caesarean section under regional anaesthesia, were included in the trial. Women were randomized to three groups: group SSS: single-shot spinal; group CSE: combined spinal-epidural; group EVE: epidural volume extension of a combined spinal-epidural. Intrathecal injection was identical in the three groups (0.5% hyperbaric bupivacaine 9 mg with fentanyl 10 microg) and was injected via a 25-gauge pencil-point spinal needle, either as a single-shot spinal or through the spinal needle of the needle-through-needle CSE set. In group EVE, 5 mL of normal saline was injected through the epidural catheter. All blocks were performed with the women sitting. Haemodynamic parameters and block characteristics were assessed.

RESULTS

The onset of maximum sensory and motor block was significantly faster in the SSS group than in the other two. Extent and duration of sensory and motor block and the incidence of adverse effects were similar in the three groups (P>0.05).

CONCLUSIONS

Intrathecal block is similar in extent and duration whether given as a single-shot spinal or a combined spinal-epidural with or without epidural volume extension when performed for elective caesarean section using hyperbaric bupivacaine in the sitting position.