Isobaric Group Research Articles

A comparative study of low-dose intrathecal bupivacaine 0.5% (heavy), levobupivacaine 0.5% (plain), and levobupivacaine 0.5% (heavy) with fentanyl as an adjuvant in transurethral resection of prostate surgery: A prospective randomized study

Background: Spinal anesthesia is the technique of choice for transurethral resection of the prostate (TURP) surgeries. Levobupivacaine, an S-enantiomer of bupivacaine, is less cardiotoxic than bupivacaine; therefore, a low dose of local anesthetic with fentanyl as an adjuvant has been used to decrease toxicity and increase efficacy. Aims and Objectives: The aim of this study was to compare and evaluate the efficacy of hyperbaric bupivacaine 0.5%, isobaric levobupivacaine 0.5%, and hyperbaric levobupivacaine 0.5% with fentanyl as an adjuvant. Materials and Methods: One hundred and five patients scheduled for elective TURP surgeries were randomly divided into three groups. Group BH (n=35) received 1.5 mL of 0.5% hyperbaric bupivacaine with 25 μg of fentanyl, Group LH (n=35) received 1.5 mL of 0.5% hyperbaric levobupivacaine with 25 μg of fentanyl, and Group LP (n=35) received 1.5 mL of 0.5% isobaric levobupivacaine with 25 μg of fentanyl intrathecally. Results: The onset of sensory and motor block was earlier and the duration of analgesia and motor block were longer in the BH group (P<0.001) as compared to LH and LP groups. The demographic data, duration of surgery, heart rate, SpO2, pruritus, and shivering were comparable between the groups (P>0.05). The visual analog scale score was higher in the LP group. Hypotension, nausea, and vomiting were seen in the BH group. Conclusion: Hyperbaric is better than isobaric group due to quicker onset and longer duration. Levobupivacaine is better than bupivacaine in terms of the early mobilization and a lesser incidence of side effects, making hyperbaric levobupivacaine a better alternative to isobaric levobupivacaine and hyperbaric bupivacaine.

Effects of Hyperbaric and Isobaric Bupivacaine on Hemodynamic Profiles and Block Characteristics Among Parturients Undergoing Elective Cesarean Section Under Spinal Anesthesia: A Randomized Controlled Trial.

Cesarean section (CS) is a surgical procedure where the baby is delivered through incisions made in the abdomen and uterus. Bupivacaine is a widely recognized local anesthetic available in different baricity and it is frequently used for spinal anesthesia. The baricity of bupivacaine impacts hemodynamic profiles and block characteristics. To compare the effects of hyperbaric and isobaric bupivacaine on hemodynamic profiles and block characteristics among parturients undergoing elective cesarean section under spinal anesthesia at Dilla University Referral Hospital. 64 pregnant mothers scheduled for elective cesarean section under spinal anesthesia were randomly assigned to two groups: Group A received a dose of 12.5 mg of isobaric bupivacaine (n = 32), Group B received a dose of 12.5 mg of hyperbaric bupivacaine (n = 32). Prior to conducting the study, the necessary ethical approvals were obtained. For comparing numerical variables between the two groups, the independent Sample t-test or Mann-Whitney U-test was employed as needed. Repeated measurements were analyzed using mixed ANOVA. Categorical variables were assessed using either the chi-square test or Fisher's exact test. Statistical significance was set at P < 0.05, with a power of 90%. The mean Systolic Blood Pressure (SBP), Diastolic Blood pressure (DBP), and Mean Arterial Blood Pressure (MAP) showed significant decrement in the group receiving isobaric spinal anesthesia compared to those receiving hyperbaric bupivacaine. The decrement was observed from the 6th to 30th minute (p<0.05). Furthermore, the hyperbaric group had a faster onset time for achieving the maximum sensory block, with a median time of 3 (1) min compared to 4 (2) mins in the isobaric group (p<0.001). We conclude that hyperbaric bupivacaine provides stable intraoperative hemodynamic parameters and an earlier onset of block than isobaric bupivacaine. Therefore, we recommend clinicians to use hyperbaric bupivacaine for cesarean delivery.

Development of a Rapid, Targeted LC-IM-MS Method for Anabolic Steroids.

Anabolic steroids are of high biological interest due to their involvement in human development and disease progression. Additionally, they are banned in sport due to their performance-enhancing characteristics. Analytical challenges associated with their measurement stem from structural heterogeneity, poor ionization efficiency, and low natural abundance. Their importance in a variety of clinically relevant assays has prompted the consideration of integrating ion mobility spectrometry (IMS) into existing LC-MS assays, due primarily to its speed and structure-based separation capability. Herein we have optimized a rapid (2 min) targeted LC-IM-MS method for the detection and quantification of 40 anabolic steroids and their metabolites. First, a steroid-specific calibrant mixture was developed to cover the full range of retention time, mobility, and accurate mass. Importantly, this use of this calibrant mixture provided robust and reproducible measurements based on collision cross section (CCS) with interday reproducibility of <0.5%. Furthermore, the combined separation power of LC coupled to IM provided comprehensive differentiation of isomers/isobars within 6 different isobaric groups. Multiplexed IM acquisition also provided improved limits of detection, which were well below 1 ng/mL in almost all compounds measured. This method was also capable of steroid profiling, providing quantitative ratios (e.g., testosterone/epitestosterone, androsterone/etiocholanolone, etc.). Lastly, phase II steroid metabolites were probed in lieu of hydrolysis to demonstrate the ability to separate those analytes and provide information beyond total steroid concentration. This method has tremendous potential for rapid analysis of steroid profiles in human urine spanning a variety of applications from developmental disorders to doping in sport.

Comparative study of intrathecal isobaric and hyperbaric ropivacaine in cesarean delivery

Spinal Anesthesia is a common safe, economical, easy to perform and effective technique which provides rapid and reliable anesthesia with muscle relaxation for pts undergoing lower abdominal surgery. Aim: To compare isobaric and hyperbaric ropivacaine in patients undergoing cesarean delivery Materials and Methods: Prospective Observational Clinical Study patients admitted for elective cesearan Delivery. The Duration of study is one year. 80 patients , aged 21 years to 30 years , belongs to ASA physical status 1 &amp; 2, posted for elective Caesarean delivery under spinal Anaesthesia. These patients are divided into two groups of 40 patients Each. Group I : patients received 2ml of 0.75% Isobaric Ropivacaine (isobaric group), Group H: patients received 2 ml of 0.75% hyperbaric Ropivacaine in dextrose 50mg/ml (Hyperbaric group). There was no significant difference in the onset of sensory block. Time from injection to highest sensory block is significantly higher in isobaric group [ Group-I], when compared to hyperbaric group [ Group-H]. Time for onset of modified bromage grade 3 is longer in isobaric group than hyperbaric group. Time for motor regression is faster in hyperbaric group than in isobaric group so that early mobilization in hyperbaric group patients than isobaric group patients is possible.

Comparative study of intrathecal isobaric and hyperbaric ropivacaine in Caesarean delivery

Spinal Anesthesia is a common safe, economical, easy to perform and effective technique which provides rapid and reliable anesthesia with muscle relaxation for pts undergoing lower abdominal surgery. To compare isobaric and hyperbaric ropivacaine in patients undergoing cesarean delivery. Prospective Observational Clinical Study patients admitted for elective cesearan Delivery. The Duration of study is one year. 80 patients, aged 21 years to 30 years, belongs to ASA physical status 1 &amp; 2, posted for elective Caesarean delivery under spinal Anaesthesia. These patients are divided into two groups of 40 patients Each. Group I : patients received 2ml of 0.75% Isobaric Ropivacaine (isobaric group), Group H: patients received 2 ml of 0.75% hyperbaric Ropivacaine in dextrose 50mg/ml (Hyperbaric group). There was no significant difference in the onset of sensory block. Time from injection to highest sensory block is significantly higher in isobaric group [Group-I], when compared to hyperbaric group [Group-H]. Time for onset of modified bromage grade 3 is longer in isobaric group than hyperbaric group. Time for motor regression is faster in hyperbaric group than in isobaric group so that early mobilization in hyperbaric group patients than isobaric group patients is possible.

Finding Most Stable Isobar for Nuclides with Mass Number (165- 175) against Beta Decay

In the beta decay process, a neutron converts into a proton, or vice versa, so the atom in this process changes to a more stable isobar. Bethe-Weizsäcker used a quasi-experimental formula in the present study to find the most stable isobar for isobaric groups of mass nuclides (A=165-175). In a group of isobars, there are two methods of calculating the most stable isobar. The most stable isobar represents the lowest parabola value by calculating the binding energy value (B.E) for each nuclide in this family, and then drawing these binding energy values as a function of the atomic number (Z) in order to obtain the mass parabolas, the second method is by calculating the atomic number value of the most stable isobar (ZA). The results show that the mass parabolas of isobar elements with an even mass number (A=even) vary from the mass parabolas of isobar elements with an odd mass number (A=odd), In the case of single isobars, it has one parabola, meaning that it has one stable isobar, while we find that the pairs isobars appear to have two parabolas, meaning that it has more than one stable isobar. When we compared the two methods used in this study to determine the most stable isobars, we found that in two techniques for odd isobars, stable isobars are mostly the same nuclide, whereas in suitcases of even isobars with two stable isobars (only one of them are same stable isobars).

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

BackgroundSpinal 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.MethodsA 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.ResultsThe 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).ConclusionBaricity 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.

Transformation of dissolved organic matter during advanced coal liquefaction wastewater treatment and analysis of its molecular characteristics

Coal liquefaction wastewater (CLW) contains numerous toxic and biorefractory organics. A series of advanced treatment processes were designed to remove the dissolved organic matter (DOM) from CLW. Here, the reactivity and state of the DOM in the treatment train were studied in relation to its chemical composition by a Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) analysis. Within an isobaric group, the raw CLW possessed a high average double-bond equivalent (DBEwa) and low H/Cwa values with the N- and S-containing compounds accounting for approximately 77% of the raw CLW, which represented lignin (73.6%) and condensed aromatic structures (19.8%). In addition, the flotation process removed some hydrophobic DOM compounds with highly unsaturated states, which were biorefractory compounds. Ozonation and catalytic oxidation processes preferentially removed the highly unsaturated compounds and produced more oxidized molecules. The biofiltration process impacted the organics composition by consuming oxygen-rich substances, whereas the anoxic/oxic (A/O) process converted the reactive compounds into newly formed compounds through the loss of hydrogen (unsaturation) from the original compounds. The membrane bioreactor (MBR) process was more efficient in removing the N-containing compounds with higher unsaturated states. The compounds resistant to the applied CLW treatment processes were characterized by lower molecular weights (approximately 250–350 Da), higher oxidation states (O/S > 6), numerous carboxylic groups, and non-biodegradable features.

A feasibility study of UHPLC-HRMS accurate-mass screening methods for multiclass testing of organic contaminants in food

The feasibility of accurate-mass multi-residue screening methods using liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS) using time-of-flight mass spectrometry has been evaluated, including over 625 multiclass food contaminants as case study. Aspects such as the selectivity and confirmation capability provided by HRMS with different acquisition modes (full-scan or full-scan combined with collision induced dissociation (CID) with no precursor ion isolation), and chromatographic separation along with main limitations such as sensitivity or automated data processing have been examined. Compound identification was accomplished with retention time matching and accurate mass measurements of the targeted ions for each analyte (mainly (de)protonated molecules). Compounds with the same nominal mass (isobaric species) were very frequent due to the large number of compounds included. Although 76% of database compounds were involved in isobaric groups, they were resolved in most cases (99% of these isobaric species were distinguished by retention time, resolving power, isotopic profile or fragment ions). Only three pairs could not be resolved with these tools. In-source CID fragmentation was evaluated in depth, although the results obtained in terms of information provided were not as thorough as those obtained using fragmentation experiments without precursor ion isolation (all ion mode). The latter acquisition mode was found to be the best suited for this type of large-scale screening method instead of classic product ion scan, as provided excellent fragmentation information for confirmatory purposes for an unlimited number of compounds. Leaving aside the sample treatment limitations, the main weaknesses noticed are basically the relatively low sensitivity for compounds which does not map well against electrospray ionization and also quantitation issues such as those produced by signal suppression due to either matrix effects from coeluting matrix or from coeluting analytes present in the standards solutions which often occur as they contain hundreds of the analytes included in the screening methods.

Effect of different baricities of intrathecal bupivacaine on the quality of spinal block in elderly patients undergoing transurethral resection of the prostate

Background Elderly patients undergoing spinal anesthesia require restricted block with a low dose of a local anesthetic. Considering that the baricity of local anesthetic solutions is the primary determinant of the level of motor and sensory block in nonobstetric patients, the aim of this study was to evaluate the effect of baricity of bupivacaine on the quality of spinal block and on hemodynamics in elderly patients undergoing transurethral resection of the prostate (TURP). Materials and methods Ninety-nine patients undergoing TURP were randomized into three groups. Patients of the first group (33 patients) received intrathecal 10 mg hyperbaric bupivacaine 0.5%. The second group of patients (34 patients) received 5 mg isobaric bupivacaine added to 5 mg hyperbaric bupivacaine, resulting in what was called 'slightly hyperbaric solution'. The third group of patients (32 patients) received 10 mg isobaric bupivacaine 0.5%. All patients were injected below L2 level in the sitting position. Sensory and motor blockade was assessed, as well as the first request for analgesic, rescue analgesics, and the overall incidence of side effects. Results Onset of sensory block was comparable in the three studied groups, but motor block set earlier in the hyperbaric group and the 'slightly hyperbaric' group compared with the isobaric group. Higher sensory block was observed in the isobaric group. Recovery from sensory and motor block was earlier in the hyperbaric group. First need for analgesics was earlier in the hyperbaric group than in the 'slightly hyperbaric' and isobaric groups. Postoperative analgesia and tolerance to urinary catheter were prolonged in the isobaric and 'slightly hyperbaric' group as compared with the hyperbaric group. Conclusion Use of slightly hyperbaric bupivacaine (density = 1.013) than the traditional hyperbaric bupivacaine (density = 1.028) and the isobaric one (density = 1.007) results in good quality spinal block with fewer side effects in patients undergoing TURP.

Effect of hyperbaric factor on lidocaine-induced apoptosis in spinal neurons in rats with diabetic neuropathic pain

Objective To evaluate the effect of hyperbaric factor on lidocaine-induced apoptosis in spinal neurons in rats with diabetic neuropathic pain.Methods Healthy male Sprague-Dawley rats,weighing 220-300 g,were used in the study.Diabetic neuropathic pain was induced by high-sugar high-fat diet + intraperitoneal 1％ streptozotocin (STZ) 30 mg/kg and confirmed by blood glucose level ＞ 16.65 mmol/L at 3 days after STZ injection and then intrathecal catheter was placed.Twenty-four rats with diabetic neuropathic pain in which IT catheters were successfully implanted were randomly divided into 3 groups (n =8 each):hyperbaric lidocaine group (group HL),isobaric lidocaine group (group IL),and glucose group (group G).Another 8 rats in which IT catheters were successfully inserted served as control group (group C).2％ hyperbaric lidocaine 10 μl (in C and HL groups),2％ isobaric lidocaine 10 μl (in group IL),or 10％ glucose 10 μl (in group G) was injected intrathecally once a day for 3 consecutive days.The duration of motor block was recorded at 2 min after each administration.The paw withdrawal threshold to von Frey filament stimulation (PWT) was measured before STZ injection (T1),before IT injection (T2),at 30 min after administration on 1st,2nd and 3rd days and on day 5 after the end of administration (T3-6).All the rats were sacrificed at T6 and their L4,5 segments of the spinal cord were removed for microscopic examination.The apoptosis in spinal neurons was detected using TUNEL assay.Results Compared with the baseline value at T1,PWT was significantly decreased at T2-5 in HL,IL and G groups.PWT was significantly higher at T6 than at T2-5 in group HL.Compared with group C,the duration of motor block was significantly prolonged and the apoptotic index was increased in group HL.Compared with group IL,the duration of motor block was significantly prolonged and the apoptotic index was increased in group HL.Conclusion Hyperbaric factor can promote lidocaine-induced apoptosis in spinal neurons in rats with diabetic neuropathic pain. Key words: Specific gravity; Lidocaine; Diabeties millitus; Neuraltia; Spinal cord; Neurons; Apoptosis

Characterization of low molecular weight dissolved natural organic matter along the treatment trait of a waterworks using Fourier transform ion cyclotron resonance mass spectrometry

Dissolved natural organic matter (DOM), particularly the low molecular weight DOM, can affect the performance of water treatment processes and serve as a main precursor of disinfection by-products (DBPs) during chlorination. In this study, electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) was used to characterize the low molecular weight DOM along the treatment trait of a conventional drinking water treatment plant. The ESI FT-ICR MS data showed that various C, H, O-only class species were the major components in the source water. According to the van Krevelen diagram analysis, lignin- and tannin-like compounds were the most abundant components. Within an isobaric group, the DOM molecules with a high degree of oxidation (high O/C value) were preferentially removed during coagulation, while those with low degree of oxidation were found to be more reactive toward chlorine. In addition, 357 one-chlorine containing products and 199 two-chlorine containing products formed during chlorination were detected in the chlorination effluent sample at a high confidence level. The chlorinated products can be arranged into series, suggesting that they were originated from C, H, O-only precursor compounds, which were in series related by the replacement of CH4 against oxygen. For the first time, this study explored the behavior of low molecular weight DOM along a drinking water treatment trait on the molecular level, and revealed the presence of abundant unknown chlorinated products, which are probably rich in carboxylic and phenolic groups, in drinking water.

Clinical Characteristics of Spinal Levobupivacaine: Hyperbaric Compared with Isobaric Solution

We performed a prospective, double-blinded study in 20 patients undergoing gynecologic surgery with lower abdominal incision, to investigate characteristics of intrathecal hyperbaric levobupivacaine compared with isobaric levobupivacaine. We randomly assigned them to receive 3 mL of either isobaric or hyperbaric 0.42% levobupivacaine intrathecally. We found that hyperbaric levobupivacaine, compared with isobaric levobupivacaine, spread faster to T10 level (2.8 ± 1.1 versus 6.6 ± 4.7 minutes, P = 0.039), reached higher sensory block levels at 5 and 15 minutes after injection (T8 versus L1, P = 0.011, and T4 versus T7, P = 0.027, resp.), and had a higher peak level (T4 versus T8, P = 0.040). Isobaric levobupivacaine caused a wider range of peak levels (L1 to C8) compared with hyperbaric form (T7 to T2). The level of T4 or higher reached 90% in the hyperbaric group compared with 20% in the isobaric group (P = 0.005). Our results suggest that hyperbaric levobupivacaine was more predictable for sensory block level and more effective for surgical procedures with lower abdominal approach. Hyperbaric levobupivacaine seems to be suitable, but the optimal dosage needs further investigation.

Does the Baricity of Bupivacaine Influence Intrathecal Spread in the Prolonged Sitting Position Before Elective Cesarean Delivery? A Prospective Randomized Controlled Study

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. 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. 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). 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.

The role of combined spinal epidural analgesia for labour: is there still a question?

HEN combined spinal epidural (CSE) analgesia was introduced as a technique for labour analgesia, two distinct camps of opinion quickly emerged amongst anesthesiologists practicing obstetrical anesthesia: those who believe benefits of CSE are advantageous to every woman requesting a labour epidural; and those who believe the benefits over a standard epidural do not justify the intentional “invasion” of the dura nor the side effects. Efficacy has been well proven by a plethora of CSE studies, but safety remains a concern for many. In this issue of the Journal, Rofaeel et al. 1 report on a CSE study, examining hyperbaric bupivacaine vs isobaric bupivacaine. The study finds that when added to intrathecal (IT) sufentanil 2.5 µg, isobaric bupivacaine 2.5 mg, the standard dose which many anesthesiologists use, provides better analgesia within the first ten minutes post injection, compared to a 2.5-mg dose of hyperbaric bupivacaine. This difference disappears by 20 min post injection. The far more important finding of the study is that the incidence of sustained fetal bradycardia, defined as fetal heart rate 60 sec, was 33% in the isobaric group vs 10% in the hyperbaric group. This result is both statistically and clinically significant. While initial reports on CSE showed a high incidence of fetal bradycardia, more contemporary prospective studies, including those by Wong et al. 2 in 2005 and Van de Velde et al. 3 in 2004, report an incidence of prolonged decelerations varying between 3.9%–12%. None of the fetal bradycardias reported in Rofaeel’s study resulted in emergency obstetrical intervention, but perhaps this is a high cost to pay for a difference of ten minutes to attainment of excellent analgesia. One might conclude from this study that IT isobaric bupivacaine should no longer be used. But, it raises a more important issue: are the benefits of CSE over a standard epidural for labour analgesia enough to justify this risk of fetal harm? As a provider of CSE labour analgesia, I have established my own set of exclusion criteria based on interpretation of the literature. For instance, like the authors of this study, I do not use the technique when there is a poor fetal heart trace, nor when I wish to know the epidural catheter is functioning unequivocally at the time of insertion. I also use CSE for those who may gain the most benefit: women in advanced labour and those in extreme pain. However, given the incidence of fetal bradycardia observed in both groups of Rofaeel’s study, perhaps it is time to reassess whether CSE should continue to have a role in labour analgesia. Today, the purported benefits of CSE are: faster onset of analgesia, superior analgesia in late labour, better subsequent functioning of the epidural catheter, and higher patient satisfaction. It has been well-proven that when compared to dilute epidural solutions, CSE offers no advantage in terms of obstetrical intervention, nor any difference in the ability to be mobile. 4 The usually quoted disadvantages include: fetal bradycardia; unknown reliability of epidural catheter function; risk of central nervous system infection and respiratory depression; and significant pruritus. Risks of hypotension and post-dural puncture headache have been shown to be no different than with epidural analgesia. 4

Spinal anaesthesia for paediatric day-case surgery: a double-blind, randomized, parallel group, prospective comparison of isobaric and hyperbaric bupivacaine

We have compared bupivacaine 5 mg ml-1, either isobaric in saline 0.9% or hyperbaric in 8% glucose, for spinal anaesthesia in 100 children, aged 2-115 months, in a double-blind, randomized, parallel group, prospective study. Children were premedicated with diazepam 0.5 mg kg-1 orally. Seventy-two children were sedated before, and 25 children after, lumbar puncture, with either propofol or thiopental (thiopentone). After lumbar puncture in the lateral decubitus position with a 24-27-gauge paediatric spinal needle, isobaric or hyperbaric bupivacaine 5 mg ml-1 was injected in a dose of 0.3-0.5 mg kg-1 using a blinded procedure. Maximum cephalad extent of the block was tested by transcutaneous electrical stimulation. The success rate of the block was greater with hyperbaric bupivacaine (96%) compared with isobaric bupivacaine (82%) (P = 0.025, 95% confidence intervals (CI) 0-28%). Intense motor block was associated with adequate sensory block. Spread and duration of sensory block showed a similar wide scatter in both groups. The highest median level of sensory block was T4 (range T1-12) in the isobaric group and T4 (T1-7) in the hyperbaric group. Times to two segment regression of block were similar: 80 (55-190) min in the isobaric and 80 (30-190) min in the hyperbaric group. Cardiovascular stability was good. Etilefrin was administered to one child to treat hypotension and atropine to one child to treat bradycardia. The study gave an impression of a delayed onset time of spinal block, as most of the nine children who required either fentanyl or a sedative for a mild reaction to skin incision had complete block when transferred to the recovery room after operation. Five children developed a mild, position-dependent headache.

Comparison of Hypobaric, Hyperbaric, and Isobaric Solutions of Bupivacaine During Continuous Spinal Anesthesia

This study was designed to compare the anesthetic properties of hypobaric bupivacaine with those of isobaric and hyperbaric solutions when administered in the supine position in an elderly population undergoing hip surgery using continuous spinal anesthesia. Plain bupivacaine (0.5%) was mixed with equal volumes of 10% dextrose (hyperbaric), 0.9% NaCl (isobaric), or distilled water (hypobaric) to obtain 0.25% solutions. In a double-blind fashion, all patients received 3 mL (7.5 mg) of their particular solution injected through the spinal catheter in the horizontal supine position. The sensory level obtained in the hyperbaric group (median, T4; range, T3-L3) was significantly higher than in both the isobaric (median, T11; range, T6-L1) and hypobaric (median, L1; range, T4-L3) groups. A motor blockade of grade 2 or 3 was obtained in 14 of 15 and 12 of 15 patients in, respectively, the hyperbaric and isobaric groups, but only in 8 of 15 patients in the hypobaric group. After the initial injection of 3 mL (7.5 mg), a sensory level of T10 and a motor blockade of grade 2 or 3 was obtained in 14 of 15, 5 of 15, and 3 of 15 patients in the hyperbaric, isobaric, and hypobaric groups, respectively. All remaining patients received 1 or 2 additional milliliters (2.5-5 mg) and achieved these required anesthetic conditions, except for one patient in the hyperbaric group and eight patients in the hypobaric group in whom anesthesia was achieved with hyperbaric tetracaine. The decrease in mean arterial pressure was significantly more severe in the hyperbaric (30%) than in either the isobaric (18%) or hypobaric (14%) groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Subarachnoid Analgesia for Caesarean Section

Equal volumes (2.5 ml, 12.5 mg) of plain 0.5% bupivacaine (glucose-free) and hyperbaric 0.5% bupivacaine (in 8% glucose) were compared in a randomized double-blind study of 40 patients undergoing Caesarean section under subarachnoid anaesthesia. There were no differences in the rate of onset, maximum spread, number of patients with high cervical levels, duration of anaesthesia or incidence of post-spinal headaches between the two solutions. The median maximum cephalad levels of analgesia were (hyperbaric) T1 (range C1-T4), and (plain) T2 (range C1-T4). Thirteen patients in the hyperbaric group and 10 in the isobaric group required i.v. ephedrine to treat hypotension. Nine patients (23%) developed a post-spinal headache, and three were treated with an extradural blood patch.

SUBARACHNOID ANALGESIA FOR CAESAREAN SECTION: A Double-Blind Comparison of Plain and Hyperbaric 0.5% Bupivacaine

Equal volumes (2.5 ml, 12.5 mg) of plain 0.5% bupivacaine (glucose-free) and hyperbaric 0.5% bupivacaine (in 8% glucose) were compared in a randomized double-blind study of 40 patients undergoing Caesarean section under subarachnoid anaesthesia. There were no differences in the rate of onset, maximum spread, number of patients with high cervical levels, duration of anaesthesia or incidence of post-spinal headaches between the two solutions. The median maximum cephalad levels of analgesia were (hyperbaric) T1 (range C1-T4), and (plain) T2 (range C1-T4). Thirteen patients in the hyperbaric group and 10 in the isobaric group required i.v. ephedrine to treat hypotension. Nine patients (23%) developed a post-spinal headache, and three were treated with an extradural blood patch.

Theoretical prediction of new heavy bosons (especially heavy K-mesons) in the frame of the rotator model of elementary particles

A rotator model of elementary particles that leads to the introduction of an isobaric group that has the four baryonic particle states n, p, LAMBDA , and V/sup +/ as basic states is considered. Heavier baryons are built from the fusion' of three such basic states. New bosons and hyperons are predicted and physical identifications are made. (C.E.S.)