***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 Epidural analgesia initiated early in labor ( when the cervix is less than 4.0 cm dilated ) has been associated with an increased risk of cesarean delivery . It is unclear , however , whether this increase in risk is due to the analgesia or is attributable to other factors . METHODS We conducted a r and omized trial of 750 nulliparous women at term who were in spontaneous labor or had spontaneous rupture of the membranes and who had a cervical dilatation of less than 4.0 cm . Women were r and omly assigned to receive intrathecal fentanyl or systemic hydromorphone at the first request for analgesia . Epidural analgesia was initiated in the intrathecal group at the second request for analgesia and in the systemic group at a cervical dilatation of 4.0 cm or greater or at the third request for analgesia . The primary outcome was the rate of cesarean delivery . RESULTS The rate of cesarean delivery was not significantly different between the groups ( 17.8 percent after intrathecal analgesia vs. 20.7 percent after systemic analgesia ; 95 percent confidence interval for the difference , -9.0 to 3.0 percentage points ; P=0.31 ) . The median time from the initiation of analgesia to complete dilatation was significantly shorter after intrathecal analgesia than after systemic analgesia ( 295 minutes vs. 385 minutes , P<0.001 ) , as was the time to vaginal delivery ( 398 minutes vs. 479 minutes , P<0.001 ) . Pain scores after the first intervention were significantly lower after intrathecal analgesia than after systemic analgesia ( 2 vs. 6 on a 0-to-10 scale , P<0.001 ) . The incidence of one-minute Apgar scores below 7 was significantly higher after systemic analgesia ( 24.0 percent vs. 16.7 percent , P=0.01 ) . CONCLUSIONS Neuraxial analgesia in early labor did not increase the rate of cesarean delivery , and it provided better analgesia and result ed in a shorter duration of labor than systemic analgesia BACKGROUND Intermittent epidural bolus dosing is a method of drug delivery that can prolong the duration of labour analgesia induced by a combined spinal epidural ( CSE ) . In this r and omized , double-blinded study , we compared the analgesic efficacy of two drug delivery systems : regular intermittent epidural boluses and continuous epidural infusion and assessed the incidence of breakthrough pain after CSE . METHODS With the approval of the Hospital Ethics Committee , we recruited 60 parturients into this r and omized controlled trial . A CSE was performed with intrathecal fentanyl 25 mug in all patients . The parturients were then r and omly allocated into two groups . The infusion group received a continuous epidural infusion of levobupivacaine 0.1 % with fentanyl 2 microg/mL at a rate of 10 mL/h . The bolus group received 5-mL epidural boluses every half hour . The sample size was computed to detect a 40 % reduction in the rate of breakthrough pain . RESULTS The bolus group had a lower incidence of breakthrough pain than the infusion group ( 10 % vs. 37 % , P < 0.05 ) . The bolus group also had significantly higher satisfaction scores for labour analgesia : 97+/-8 ( mean+/-SD ) vs. 89+/-7 ( P < 0.05 ) . CONCLUSION Automated regular bolus delivery of epidural analgesia when compared with continuous infusion decreased the incidence of breakthrough pain and increased maternal satisfaction . In a busy obstetric unit , this may also serve to decrease the anesthetists ' workload The effectiveness of two epidural analgesic regimens on the ability to ambulate was compared in women in labor by a prospect i ve , r and omized , double-blind design . One group of patients received epidural fentanyl , a 75-micrograms bolus and an infusion of fentanyl 2.5 micrograms/mL at 15 mL/h ( FENT , n = 53 ) . A second group received ultra low-dose bupivacaine ( 0.04 % ) , epinephrine ( 1.7 micrograms/mL ) , and fentanyl ( 1.7 micrograms/mL ) ( BEF , n = 77 ) , a 15-mL bolus followed by an infusion at 15 mL/h . Adequate analgesia was rapidly obtained in 90.6 % of patients in the FENT group and 92.2 % of patients in the BEF group ( P = 0.89 ) . Seventy percent of patients in the FENT group ambulated versus 68 % in the other group . The BEF mixture provided analgesia of longer duration ( 287 + /- 171 min versus 156 + /- 72 min , P = 0.0001 ) . The number of patients delivering during administration of only their study drug ( without needing higher doses of local anesthetics ) was 52 % for BEF and 21 % for FENT ( P = 0.0005 ) . Hip flexion weakness precluding ambulation occurred in 17 % ( P = 0.002 ) of BEF patients and orthostatic hypotension in 9 % ( P = 0.08 ) . Neither problem occurred in FENT patients . Neonatal outcome was similar in both groups . Approximately 70 % of women receiving epidural analgesia with fentanyl or ultra low-dose bupivacaine , epinephrine , and fentanyl may ambulate safely during labor Purpose We compared the efficacy of epidural continual intermittent boluses ( CIB ) with a continuous epidural infusion ( CEI ) in prolonging labour analgesia  induced by the combined spinal epidural ( CSE ) technique . Methods CSE was instituted in 42 nulliparous parturients at the L3 to 4 level with intrathecal ( IT ) fentanyl 25 μg followed by an epidural test dose of 3 mL of 1.5 % lidocaine . These parturients were then r and omly assigned to receive either epidural CIB ( n = 21 ) or CEI ( n = 21 ) with 0.1 % ropivacaine and fentanyl 2 μg·mL−1 . For the CIB , 5 mL boluses were given hourly , with the first bolus 30 min postinduction . CEI at the rate of 5 mL·hr−1 was initiated in the minute after CSE . The duration of analgesia , pain score , degree of sensorimotor block were compared . Results From Kaplan Meier survival analysis , the duration of analgesia was significantly longer in CIB ( mean survival time 239 ± SD 24 min vs 181 ± 17,P < 0.05 using log rank test ) . During the first three hours postblock , the median sensory block to cold was higher in CIB ( P < 0.05 , Mann U Whitney test ) but no difference in blood pressure was detected ( P > 0.05 , repeated measure analysis of variance ( RMANOVA ) ] . The serial pain scores were lower in the CIB ( P < 0.05 , RMANOVA ) . Conclusion CIB prolonged the duration and improved the quality of analgesia . CIB could have result ed in an improved spread of analgesics in the epidural space or encouraged a direct passage of infusate into the IT space . This could have also rendered a higher sensory block to cold in the CIB group . CIB is a good alternative to CEI for the maintenance of epidural analgesia after CSE.RésuméObjectifComparer l’efficacité de bolus périduraux intermittents administrés en continu ( BIC ) avec la perfusion péridurale continue ( PPC ) comme analgésie prolongée pendant le travail induite selon une technique rachidienne péridurale combinée (RPC).MéthodeL’analgésie RPC a été installée chez 42 parturientes nullipares au niveau L3 à 4 avec 25 μg de fentanyl intrathécal ( IT ) suivi d’une dose test péridurale de 3 mL de lidocaïne à 1,5 % . Les patientes ont été r and omisées pour recevoir soit des BIC périduraux ( n = 21 ) , soit une PPC ( n = 21 ) avec ropivacaïne à 0,1 % et 2 μg·mL−1 de fentanyl . Dans le cas des BIC , des bolus de 5 mLà chaque heure ont été donnés , do nt le premier 30 min après l’induction . La PPC a débuté une minute après la RPC à raison de 5 mL·h−1 . La durée de l’analgésie , les scores de douleur , le degré de bloc sensorimoteur ont été comparés . RésultatsÀ partir de l’analyse de survie de Kaplan Meier , on a trouvé une analgésie significativement plus longue avec les BIC ( temps de survie moyen de 239 ± l’écart type 24 min vs 181 ± 17 , P < 0,05 avec le test du logrank ) . Pendant les trois premières heures suivant le bloc , le bloc sensitif moyen au froid a été plus élevé avec les BIC ( P < 0,05 , test U de Mann Whitney ) mais aucune différence de tension artérielle n’a été détectée [ P > 0,05 , analyse répétée de la variance à plusieurs variables ( repeated measure analysis of variance RMANOVA ) ] . Les scores de douleur en série ont été plus bas avec les BIC ( P < 0,05 , RMANOVA ) . Conclusion Les BIC ont prolongé la durée et amélioré la qualité de l’analgésie . Les BIC peuvent améliorer la diffusion de l’analgésie dans l’espace péridural ou favoriser le passage direct de la perfusion dans l’espace IT . Cette technique peut aussi avoir augmenté le bloc sensitif au froid . Les BIC sont un bon équivalent de la PPC pour le maintien de l’analgésie péridurale après la RPC BACKGROUND The minimum local analgesic concentration ( MLAC ) has been defined as the median effective local analgesic concentration in a 20-ml volume for epidural analgesia in the first stage of labor . The aim of this study was to assess the relative analgesic potencies of epidural bupivacaine and ropivacaine by determining their respective minimum local analgesic concentrations . METHODS Seventy-three parturients at < or = 7 cm cervical dilation who requested epidural analgesia were allocated to one of two groups in this double-blinded , r and omized , prospect i ve study . After a lumbar epidural catheter was placed , 20 ml of the test solution was given , either ropivacaine ( n = 34 ) or bupivacaine ( n = 39 ) . The concentration of local anesthetic was determined by the response of the previous patient in that group to a higher or lower concentration using up-down sequential allocation . Analgesic efficacy was assessed using 100-mm visual analog pain scores with < or = 10 mm within 30 min defined as effective . An effective result directed a 0.01 % wt/vol decrement for the next patient . An ineffective result directed a 0.01 % wt/vol increment . RESULTS The minimum local analgesic concentration of ropivacaine was 0.111 % wt/vol ( 95 % confidence interval , 0.100 - 0.122 ) , and the minimum local analgesic concentration of bupivacaine was 0.067 % wt/vol ( 95 % confidence interval , 0.052 - 0.082 ) . Ropivacaine was significantly less potent than bupivacaine , with a potency ratio of 0.6 ( 95 % confidence interval , 0.49 - 0.74 ) . No difference in motor effects was observed . CONCLUSION Ropivacaine was significantly less potent than bupivacaine for epidural analgesia in the first stage of labor The efficacy of an extradural infusion of 0.0625 % or 0.125 % bupivacaine was studied in 98 primigravid mothers in active labour . No special measures were taken to posture the mother ( except to avoid aorto-caval compression ) . The study regimen included a control group ( no infusion ) receiving intermittent top-ups ( 0.25 % . bupivacaine 8 - 10 ml ) , two groups receiving bupivacaine 6.25 mg h-1 infusion in different concentrations ( 0.0625 % and 0.125 % ) , a fourth group receiving 0.125 % bupivacaine 12.5 mg h-1 infusion , and a fifth group receiving 0.125 % bupivacaine 18.75 mg h-1 infusion . The optimum infusion rate was 0.125 % bupivacaine 10 ml h-1 , at which 69 % of primigravid mothers required none or only one " top-up " of 0.25 % bupivacaine 8 - 10 ml during a mean duration of 7.1 h labour . In the group who had no extradural infusion , only 32 % of mothers managed with one or no top-up . The median interval between top-ups was increased from 145 min in the no infusion group to 245 min in those mothers receiving 0.125 % bupivacaine 10 ml h 
    Output:
    
: IEB is an appealing concept ; current evidence suggests IEB slightly reduces local anesthetic usage and improves maternal satisfaction .
Given the wide CIs of the pooled results for many outcomes , definite conclusions can not be drawn for those outcomes , but there is also a potential that IEB improves instrumental delivery rate and need of anesthesia interventions .