***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background : The ideal intrathecal isobaric bupivacaine dose for cesarean delivery anesthesia is uncertain . While small doses ( 5–9 mg ) of bupivacaine may reduce side effects such as hypotension , they potentially increase spinal anesthetic failures . This study determined the ED50 and ED95 of intrathecal isobaric bupivacaine ( with adjuvant opioids ) for cesarean delivery . Methods : After institutional review board approval and written informed consent were obtained , 48 parturients undergoing elective cesarean delivery under combined spinal – epidural anesthesia were enrolled in this double-blind , r and omized , dose-ranging study . Patients received a 5- , 6- , 7- , 8- , 9- , 10- , 11- , or 12-mg intrathecal isobaric bupivacaine dose with 10 & mgr;g fentanyl and 200 & mgr;g morphine .  Overall anesthetic success was recorded when no intraoperative epidural supplement was required during the cesarean delivery . ED50 and ED95 values for overall anesthetic success were determined using a logistic regression model . Results : ED50 and ED95 values for overall anesthetic success were 7.25 and 13.0 mg , respectively . No advantages for low doses could be demonstrated with regard to hypotension , nausea , vomiting , pruritus , or maternal satisfaction , although this study was underpowered to detect significant differences in secondary outcome variables . Conclusions : The ED50 and ED95 values ( 7.25 and 13.0 mg , respectively ) for intrathecal isobaric bupivacaine in this circumstance are similar to values the authors determined recently for hyperbaric bupivacaine using similar methodology . These ED50 and ED95 values are significantly higher than those advocated in previous reports in which success was cl aim ed using lower intrathecal bupivacaine doses . The current study used stricter criteria to define “ successful ” anesthesia and support the use of larger bupivacaine doses to ensure adequate patient comfort Amethocaine 1 % solution was mixed with equal volumes of water , 0.9 % saline or 10 % dextrose to prepare respectively , hypobaric , isobaric and hyperbaric solutions which were compared for intradural spinal anaesthesia in 60 patients . Thirty patients received 10 mg and 30 patients received 15 mg of amethocaine .  Injections were made with the patients in the lateral recumbent position and the operating table was horizontal during and after injection . Equal numbers of patients and equal numbers of males and females received hypobaric , isobaric and hyperbaric solutions . The mean spread of analgesia after the hyperbaric solution was five dermatomes greater than after the other two solutions , but the extent of analgesia was not significantly different whether amethocaine 10 mg or 15 mg was injected . The mean duration of analgesia after the hyperbaric solution was 285 min compared with 332 min and 360 min after the isobaric and hypobaric solutions respectively . The mean duration of analgesia after amethocaine 15 mg was significantly greater than after 10 mg The safety of 0.5 % hyperbaric bupivacaine , as well as the incidence and severity of visceral pain , were evaluated in 36 women undergoing elective cesarean section under spinal anesthesia who , r and omly divided into two groups , received different dose ranges according to height , 7.5–10 mg in group A and 10–12.5 mg in group B. When sensory block to at least the fourth thoracic dermatome was established , surgery was begun and the occurrence and severity of visceral pain recorded ( visual analog scale ) by an observer unaware of patient data . The level of analgesia to pinprick was determined when and if there was onset of pain intraoperatively , and supplementary medication was administered as needed . Hypotension , the incidence of which was similar in both groups , was treated as necessary with ephedrine . No patients experienced pain until after delivery of the infant . Thereafter , moderate to severe pain , in association with peritoneal traction , occurred in 12 patients in group A ( 70.5 % ) but only in 6 patients in group B ( 31.6 % ) . In patients experiencing moderate to severe pain , the mean time between induction of anesthesia and onset of pain was similar in both groups , as was the amount of systemic narcotic given . Total time for regression of sensory analgesia to L5 was longer in patients in group B ( 243.9 versus 195.4 min ) , and the incidence of complete motor blockade was greater in group B. Increasing the amount of 0.5 % hyperbaric bupivacaine per spinal segment reduces the occurrence of moderate to severe visceral pain during elective cesarean section without jeopardizing mother or fetus Background Maternal hypotension occurs in 60–94 % of Cesarean deliveries with 10–15 mg spinal bupivacaine . Reduced doses of bupivacaine may decrease the incidence of hypotension , nausea , and vasopressor use . The primary objective of this study was to compare 4.5 mg and 12 mg doses of intrathecal bupivacaine on maternal hemodynamics . The secondary objective was to determine if anticipated reductions in side effects were reflected in increased patient satisfaction . Methods Following Research Ethics Board approval and informed consent 52 term parturients undergoing elective Cesarean delivery were r and omly assigned to isobaric bupivacaine 4.5 mg or hyperbaric bupivacaine 12 mg for spinal anesthesia . All patients received fentanyl 50 μg and morphine 200 μg intrathecally . Intravenous fluid and vasopressor administration were st and ardized . Maternal hemodynamics , and sensorimotor levels were recorded at regular intervals . Side effects and patient satisfaction were documented . Results Median cepahalad sensory block was C8 in both groups ( NS ) but the intensity of motor block was significantly less ( P < 0.001 ) and of shorter duration ( P < 0.001 ) with bupivacaine 4.5 mg . The proportion of patients requiring ephedrine  ( > 70 % ) and the quantities of ephedrine used were similar in both groups ( NS ) . Use of supplemental analgesia , side effects , and measures of patient satisfaction were comparable in both groups . Discussion Intrathecal bupivacaine 4.5 and 12 mg yielded similar sensory block and side effects during Cesarean delivery . Patients receiving 4.5 mg did , however , experience significantly less motor blockade of shorter duration . Context eL’hypotension maternelle se rencontre dans 60’94 % des accouchements par césarienne avec 10’15 mg de bupivacaïne intrathécale . Des doses réduites de bupivacaïne pourraient réduire l’incidence d’hypotension et de nausées , ainsi que l’utilisation de vasopresseurs . L’objectif premier de cette étude était de comparer l’effet de doses intrathécales de bupivacaïne de 4,5 mg et 12 mg respectivement sur l’hémodynamie maternelle . Le deuxième objectif était de déterminer si les réductions anticipées d’effets secondaires se reflétaient par une satisfaction accrue des patientes . MéthodeLe Comité d’éthique de la recherche ayant donné son accord , cinquante-deux parturientes à terme devant subir un accouchement non urgent par césarienne ont été r and omisées en deux groupes pour la rachianesthésie : bupivacaïne isobare 4,5 mg ou bupivacaïne hyperbare 12 mg . Toutes les patientes ont reçu du fentanyl 50 μg et de la morphine 200 μg en intrathécal . L’administration de liquide intraveineux et de vasopresseurs a été st and ardisée . L’hémodynamie maternelle ainsi que les niveaux sensori-moteurs ont été enregistrés à intervalles réguliers . Les effets secondaires et la satisfaction des patientes ont été documentés . RésultatsLe bloc sensitif moyen en direction de la tête était situé à C8 dans les deux groupes ( NS ) , mais l’intensité du bloc moteur était significativement plus faible ( P < 0,001 ) et d’une durée moindre ( P < 0,001 ) avec la bupivacaïne 4,5 mg . La proportion de patientes nécessitant de l’éphédrine ( > 70 % ) et les quantités d’éphédrine administrées étaient similaires dans les deux groupes ( NS ) . L’utilisation d’analgésie supplémentaire , les effets secondaires et la satisfaction des patientes étaient comparables dans les deux groupes . Discussion Dans le cas d’accouchements par césarienne , les doses de 4,5 mget 12 mg de bupivacaïne intrathécale produisent un bloc sensitif et des effets secondaires similaires . Toutefois , les patientes ayant reçu 4,5 mg ont ressenti un bloc moteur plus faible et plus court , et cette différence était significative BACKGROUND Hypotension after spinal anesthesia  for cesarean section is common and may result in serious complications despite the use of uterine displacement and volume preloading . Adequate amount of hyperbaric bupivacaine for Japanese parturients whose frames are generally smaller than those of Caucasian counterparts have not yet been examined . We compared the analgesic efficacy and the incidence of hypotension with 8 mg versus 10 mg hyperbaric bupivacaine during spinal anesthesia for cesarean section in Japanese parturients . METHODS Thirty six parturients were r and omly divided into two groups , one receiving 8 mg ( n = 19 ) and the other receiving 10 mg ( n = 17 ) hyperbaric bupivacaine .  Sensory block level and the incidence of hypotension were evaluated from the time of injection to delivery . Hypotension was defined as a decrease in systolic blood pressure below 100 mmHg and to less than 80 % of the baseline value . RESULTS 15 minutes after spinal injection , the difference in sensory block level was not significant . Ten minutes after the spinal anesthesia , in 79 % of 8 mg group and in 88 % of 10 mg group , sensory block level reached T 4 . Hypotension occurred in 19 parturients ( 7 in 8 mg group and 12 in 10 mg group ) . The incidence of hypotension was significantly lower in 8 mg group ( 37 % ) than in 10 mg group ( 71 % ) . There were no significant differences either in neonatal Apgar scores or umbilical blood gas pH. CONCLUSIONS Injection of 8 mg hyperbaric bupivacaine is preferable than 10 mg in spinal anesthesia for cesarean section to obtain adequate analgesic efficacy and to avoid maternal hypotension INTRODUCTION Spinal anesthesia is the technique most often applied in cases of scheduled cesarean section . Many authors have tried decreasing the local anesthetic dose by adding opioids to achieve adequate analgesia with greater hemodynamic stability , although the ideal dose remains to be established . Our aim was to analyze hemodynamic stability and quality of analgesia with 2 different regimens for administering spinal hyperbaric bupivacaine . METHODS We design ed a controlled , double-blind trial comparing 2 doses of spinal hyperbaric bupivacaine with fentanyl in 42 patients undergoing elective cesarean section r and omized to 2 groups to receive either the low dose or the conventional one . One group received an 11 mg dose of bupivacaine and the other group received a 6.5 mg dose , combined with 20 microg of fentanyl in both cases . RESULTS The hemodynamic profile and the level of maximum sensory block obtained were similar in the two groups . The motor block was less intense in patients receiving the lower dose and it was necessary to convert 2 patients ( 10 % ) to general anesthesia in that group . CONCLUSIONS Spinal anesthesia with low doses of bupivacaine and fentanyl provides acceptable intraoperative conditions for a high percentage of patients undergoing cesarean section , with a similar incidence of hypotension . The low dose generates a less intense intraoperative motor blockade with similar spread of the sensory block . The low dose was not efficacious for 10 % of the patients who received it Purpose Spinal anesthesia for cesarean section is associated with a high incidence of maternal hypotension . The aim of this study was to assess the efficacy of low-dose bupivacaine with fentanyl to reduce the incidence of hypotension in spinal anesthesia for cesarean section . Methods Forty pregnant women undergoing elective cesarean section were r and omly allocated to two groups ; those receiving 10 mg bupivacaine to group B ( n = 20 ) and those receiving 4 mg bupivacaine plus 25 μg fentanyl to group BF ( n = 20 ) ; the agents were given intrathecally with patients in the sitting position , with a combined spinal-epidural technique . Results Sensory block was adequate for surgery in all patients . Hypotension occurred in all patients in group B ( 100 % ) and in 15 patients in group BF ( 75 % ) . The incidence of hypotension , number of ephedrine treatments , and need for ephed 
    Output:
    
Neonatal outcomes ( Apgar score , acid-base status ) and clinical quality variables ( patient satisfaction , surgical conditions ) showed non-significant differences between LD and CD .
This meta- analysis demonstrates that low-dose bupivacaine in spinal anaesthesia compromises anaesthetic efficacy ( risk of analgesic supplementation : high grade of evidence ) , despite the benefit of lower maternal side-effects ( hypotension , nausea/vomiting : moderate grade of evidence )