***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 
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    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 To compare the efficacy and side effects of 0.2 mg intrathecal ( IT ) morphine with 0.125 % epidural bupivacaine , 62 women in labor were studied . They were r and omly divided into three groups : group 1 ( n = 20 ) received IT morphine ; group 2 ( n = 22 ) received epidural bupivacaine ; and group 3 ( n = 20 ) received a combination of both using a combined spinal-epidural ( CSE ) technique . According to a visual analogue scale for assessing analgesia , neither IT 0.2 mg morphine nor 10 ml 0.125 % epidural bupivacaine was effective in producing adequate pain relief in labor , whereas the combination produced excellent analgesia . The use of IT morphine significantly reduced the dosage requirement of epidural bupivacaine .  The incidence of nausea , vomiting , and pruritus was significantly higher when IT morphine had been administered , whereas that of urinary retention did not differ . No serious respiratory depression occurred in any of the patients . When the course of labor was studied , the prior use of IT morphine significantly prolonged the duration of the first stage of labor and the total duration of labor . We conclude that the administration of 0.2 mg IT morphine in combination with epidural administration of 0.125 % bupivacaine provides better analgesia than the administration of either drug alone Intrathecal opioids can provide labor analgesia . We attempted to prolong the duration of intrathecal sufentanil analgesia by adding epinephrine or morphine .  Forty-one healthy , term nulliparae with cervical dilation < 5 cm participated in this double-blind , r and omized protocol . Using a combined spinal and epidural technique , we gave intrathecal injections of either sufentanil 10 micrograms , sufentanil 10 micrograms plus epinephrine 200 micrograms , or sufentanil 10 micrograms plus morphine 250 micrograms . At baseline and every 5 min for 30 min thereafter , we recorded arterial blood pressure and asked the patients to rate their pain , nausea , and pruritus on visual analog scales . The women continued to rate these variables every 30 min until they requested additional analgesia . They then received 10 mL of 0.25 % bupivacaine via the epidural catheter , and rated the above variables every 30 min until they requested additional epidural drug injection . Both morphine and epinephrine prolonged the duration of sufentanil analgesia . Only morphine prolonged analgesia after the first dose of epidural bupivacaine . However , because women in the morphine group experienced significantly more side effects throughout the study period , we do not recommend intrathecal morphine for labor analgesia Objective : To evaluate the use of intrapartum intrathecal narcotic analgesia in the obstetric population of our community-based hospital . Methods : A protocol to administer intrapartum intrathecal narcotic analgesia was established at our institution in December 1992 . All patients consenting to this procedure received a single lumbar intrathecal injection of 25 μg fentanyl and 0.25 mg morphine sulfate through a 25-gauge spinal needle .  Only those patients with singleton pregnancies in the vertex presentation were included in this study . The study group was matched by gravidity and parity with singleton pregnancies delivered during the study period . Patients in the study group were asked to complete an  analgesia satisfaction survey using a five-point Likert scale ranging from 0 for total dissatisfaction to 5 for total satisfaction . Results : A total of 75 patients were assigned to each group ; the control and study groups were similar with respect to age , race , estimated gestational age , infant birth weight , interval between rupture of membranes and delivery , and mode of delivery . The length of the first and second stages of labor and the incidence of fetal malposition were not significantly different between the two groups . Frequent side effects of this analgesia included complaints of pruritus ( 81.3 % ) , urinary retention ( 53.3 % ) , and nausea and vomiting ( 44.0 % ) . Headaches were less common ( 9.3 % ) , with two ( 2.7 % ) of seven patients requiring an epidural blood patch for relief . Infrequent side effects included respiratory depression ( 1.3 % ) and oversedation ( 1.3 % ) . Patients were generally satisfied with the degree of pain relief obtained , rating it highly during the first and second stages of labor and in comparison to their previous labor experience . Conclusion : The use of intrapartum intrathecal narcotic analgesia provides a satisfactory level of pain relief without disrupting the normal course of labor . ( Obstet Gynecol 1994;84:931 - 6 Early first-stage labor pain is primarily visceral in origin . Increasing pain intensity and transition to somatic nociceptive input characterizes late first- and second-stage labor pain . The effect of this change in nociceptive input on the duration of intrathecal labor analgesia  has not been well studied . This prospect i ve cohort observational study compares the duration of  intrathecal labor analgesia  after intrathecal injections made in early labor ( 3- to 5-cm cervical dilation ) and those made in more advanced labor ( 7- to 10-cm cervical dilation ) . Forty-one parturients ( 18 in early labor and 23 in advanced labor ) received intrathecal sufentanil ( 10 micro g ) and bupivacaine ( 2.5 mg ) as part of a combined spinal-epidural technique . Patients rated their pain using a 0 - 10 verbal pain scale prior to intrathecal injection and every 20 min thereafter . Duration of analgesia was defined as the lesser of time until the pain score exceeded 5 or until a request for supplemental epidural analgesia was made . The duration of spinal analgesia was significantly less when intrathecal injection was made in advanced labor ( 120 + /- 26 min ) compared with early labor ( 163 + /- 57 min , P < 0.01 ) . We conclude that cervical dilation and stage of labor significantly impact the effective duration of  intrathecal sufentanil/bupivacaine labor analgesia . ( Anesth Analg 1997;84:1108 - 12 We design ed a prospect i ve , r and omized , double-blind study to evaluate the efficacy of the combination of intrathecal sufentanil with a low dose of local anesthetic in an attempt to prolong analgesia in labor . Fifty-two patients received one of the following intrathecal study solutions : 2.5 mg of bupivacaine ; 10 micro gram of sufentanil ; or 2.5 mg of bupivacaine plus 10 micro gram of sufentanil . The mean duration of analgesia ( min + /- SD ) was significantly different among all three groups : 70 + /- 34 min for bupivacaine , 114 + /- 26 min for sufentanil , and 148 + /- 27 min for bupivacaine-sufentanil ( P < 0.001 ) . Visual analog scale ( VAS ) scores for pain were significantly higher in the bupivacaine group compared to both the sufentanil group and the bupivacaine-sufentanil group ( P < 0.02 ) , and were significantly higher in the sufentanil group compared to bupivacaine-sufentanil at 75 min postinjection and beyond ( P < 0.02 ) . Hypotension was not observed in the sufentanil group but occurred transiently in the other two groups ( P = 0.09 ) . There was no evidence of motor blockade , excessive somnolence , fetal heart rate ( FHR ) abnormalities , or postdural puncture headache ( PDPH ) in any of the patients . The addition of 2.5 mg of bupivacaine to 10 micro gram of intrathecal sufentanil significantly prolonged labor analgesia without adverse maternal or fetal effects . ( Anesth Analg 1995;81:305 - 9 Background Although intrathecal sufentanil has been reported to provide rapid-onset , complete analgesia lasting 1–3 h for the first stage of labor , no well-controlled double-blind study has compared this technique to the use of epidurally administered local anesthetics . Methods Fifty healthy parturient women requesting labor analgesia were studied . In a combined spinal-epldural technique , a spinal needle was inserted through the epidural needle before insertion of the epidural catheter . Patients were r and omly assigned to receive either intrathecal sufentanil ( 10 μg ) and epidural saline , or intrathecal saline and epidural bupivacaine ( 30 mg ) . Visual analog scores for pain , blood pressure , heart rate , sensory levels , and the incidence of nausea , pruritus , and motor blockade were recorded . Results Patients receiving intrathecal sufentanil had significantly lower visual analog pain scores at 5 , 15 , and 30 min after injection and a greater duration of analgesia before requesting additional medication ( mean 123 vs. 68 min for those receiving bupivacaine ; P < 0.05 ) . These patients also experienced pruritus more frequently but motor blockade less frequently than patients receiving epidural bupivacaine . The groups exhibited dermatomal sensory deficits to pin prick as well as bradycardia and hypotension with equal frequency . The length of labor and type of delivery were similar between the groups . No patient experienced a post-dural puncture headache . Conclusions The rapid onset of analgesia and lack of motor blockade from intrathecal sufentanil injection may be advantageous in certain clinical situations . With this technique , however , pruritus is common ; hypotension may occur ; and extensive dermatomal spread suggests that early-onset respiratory depression could occur . Therefore , blood pressure and respiratory adequacy should be monitored if intrathecal sufentanil is used The combination intrathecal fentanyl ( 25 & mgr;g ) and bupivacaine ( 2.5 mg ) provides effective labor analgesia for approximately 90 minutes . The purpose of this prospect i ve , r and omized , double-blinded investigation was to determine if the addition of morphine ( 150 & mgr;g ) to the intrathecal combination of fentanyl ( 25 & mgr;g ) and bupivacaine ( 2.5 mg ) would prolong labor analgesia . By using the combined spinal epidural technique , 95 healthy primiparous laboring women in early labor received 2 mL of one of the two intrathecal study solutions , either FB ( n = 48 ) : fentanyl ( 25 & mgr;g ) and bupivacaine ( 2.5 mg ) ; or FBM ( n = 47 ) : fentanyl ( 25 & mgr;g ) and bupivacaine ( 2.5 mg ) plus morphine ( 150 & mgr;g ) . The mean duration of labor analgesia was significantly longer in the FBM group than in the FB group ( 252 ± 63 min vs 148 ± 44 min , P < 0.01 ) . There were no significant differences between the two groups regarding the sensory levels , the incidence of nausea , vomiting , pruritus , hypotension , or operative delivery . In conclusion , the addition of 150 & mgr;g of morphine to the intr 
    Output:
    
MAIN MESSAGE The literature supports use of ITN as a safe and effective alternative to epidural anesthesia .
The advantage of single-dose ITN is that fewer physicians and nurses are needed to administer it even though its safety and effectiveness are comparable with other analgesics .
Use of ITN is associated with a shorter first stage of labour and more rapid cervical dilation .
A combination of 2.5 mg of bupivacaine , 25 microg of fentanyl , and 250 microg of morphine intrathecally usually provides a 4-hour window of acceptable analgesia for patients without complications not anticipating protracted labour .
Physicians practising modern obstetrics in rural and small urban centres might find single-dose ITN a useful alternative to parenteral or epidural analgesia for appropriately selected patients