| JOURNAL HOME | CME HOME | THIS MONTH | PAST ISSUES | ETOC | COLLECTIONS |
| AUTHORS | REVIEWERS | EDITORIAL BOARD | FEEDBACK | RSS | HELP |
 
|
|
|
||
|
|
© 2000 International Anesthesia Research Society
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Dilute concentrations of bupivacaine combined with fentanyl have recently been used to initiate labor epidural analgesia in an attempt to balance adequate analgesia and minimal maternal motor blockade. Similar concentrations of ropivacaine have not been evaluated. This prospective, randomized, double-blinded study was designed to compare the efficacy of 20 mL of either 0.08% bupivacaine plus 2 µg/mL fentanyl or 0.08% ropivacaine plus 2 µg/mL fentanyl to initiate ambulatory labor epidural analgesia. Forty nulliparous women in early (
5 cm) established labor received either 20 mL of 0.08% bupivacaine plus 2 µg/mL fentanyl (BF) or 0.08% ropivacaine plus 2 µg/mL fentanyl (RF) to initiate epidural analgesia. One woman (BF) required supplemental analgesia, and two (one BF and one RF) had visual analog scale scores > 0 but < 20 at 20 min. The time (mean ± SD) to visual analog scale score = 0 was BF (n = 18): 12.0 ± 4.5 min and RF (n = 19): 12.4 ± 4.0 min (P > 0.05). Spontaneous micturition was observed in 65% (13 of 20) BF compared with 100% (20 of 20) RF (P < 0.01), and ambulation was demonstrated in 75% (15 of 20) BF compared with 100% (20 of 20) RF (P < 0.03). The incidence of forceps delivery was 35% (7 of 20) BF compared with 10% (2 of 20) RF (P < 0.04). The results of this study indicate that dilute ropivacaine combined with fentanyl effectively initiates epidural analgesia while concurrently preserving maternal ability to void and ambulate.
Implications: As compared with a similar dilute concentration of bupivacaine, 20 mL of dilute (0.08%) ropivacaine combined with fentanyl (2 µg/mL) effectively initiates epidural analgesia in nulliparous women in early, established labor while preserving their ability to micturate and ambulate. Of importance, it appears that a true ambulatory epidural analgesic for women in labor is now possible.
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Dilute concentrations of bupivacaine combined with fentanyl have been used to maintain labor epidural analgesia (LEA) in attempts to balance adequate analgesia and minimal motor blockade (1,2). These combinations have been used to initiate LEA (3–6). Initiation of effective LEA (visual analog scale score < 30) was reported in 80% of women with a 15-mL bolus of 0.1% (15 mg) bupivacaine + 2 µg/mL (30 mcg) fentanyl (3). In another study, 65% of parturients were able to ambulate after LEA initiated with a 15-mL bolus of 0.1% bupivacaine (15 mg) + 5 µg/mL (75 µg) fentanyl (4). We have observed effective initiation of LEA with 20 mL of 0.08% (16 mg) bupivacaine + 2 µg/mL (40 µg) fentanyl in four fractionated (5-mL) boluses and similar rates of ambulation. Ropivacaine has recently become available and may provide effective LEA at similar dilute concentrations (0.08%) when combined with fentanyl (2 µg/mL), while concurrently preserving maternal ambulation.
This is the first prospective, randomized, double-blinded study designed to compare dilute concentrations of bupivacaine with ropivacaine (both combined with fentanyl) to initiate ambulatory LEA.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
After institutional review board approval and written informed consent were obtained, 40 nulliparous, term parturients, classified as ASA physical status I or II, who requested epidural analgesia were enrolled. Only women in established labor with cervical dilation of
5 cm and a reassuring fetal heart rate (FHR) tracing were considered for inclusion in the study. Determination of cervical dilation was required within 30 min of recruitment. Parturients were randomized, by using a computer-generated randomization table, to receive 20 mL of one of two study solutions to initiate LEA. The study solutions consisted of either (BF): 0.08% (16 mg) bupivacaine plus 2 µg/mL (40 µg) fentanyl; or (RF): 0.08% (16 mg) ropivacaine plus 2 µg/mL (40 µg) fentanyl. Each study solution was prepared by an anesthesiologist or nurse not involved in the study. The solutions were attained by adding 20 mL of 0.5% bupivacaine (100 mg) or ropivacaine (100 mg) and 5 mL of fentanyl (250 µg) to a 100-mL bag of preservative-free 0.9% saline. The resultant 125 mL had a concentration of 0.08% (bupivacaine or ropivacaine) plus 2 µg/mL fentanyl. A volume of 20 mL was then removed and given to the blinded investigator to initiate LEA. The remaining 105 mL of the study solution was then used for maintenance analgesia administered via patient-controlled epidural analgesia (PCEA).
On request for LEA, each parturient received IV 500-1000 mL of a balanced salt solution before the initiation of epidural analgesia. The procedure was performed at either the L3-4 or L4-5 interspace, with all patients in the sitting position. The epidural space was identified with a 17-gauge epidural needle by using a loss-of-resistance technique. A 20-gauge multiple-orifice epidural catheter was then inserted 4–5 cm into the epidural space. Aspiration was attempted from the epidural catheter in an effort to detect either intravascular or intrathecal placement of the catheter. The initial 5-mL bolus of the study solution was then injected. The epidural catheter was then secured and the parturient placed in the supine position with left uterine displacement with the head of the bed elevated 20–30 degrees. If no adverse sequelae were observed within 3 min, the remainder of the study solution was administered in three equal incremental boluses of 5 mL. The total time permitted to inject the entire 20-mL volume of the study solution was less than 5 min.
The epidural catheter was connected to the PCEA infusion pump 20 min after the administration of the study solution. Each parturient was instructed in proper PCEA use once analgesia had been established. The PCEA infusion device was programmed with the standardized parameters of a 5-mL bolus and a 10-min lockout period using the study solution. No continuous epidural background infusion of the study solution was administered. There were no hourly restrictions on the number of self-administered boluses that could be demanded or delivered. Further management of PCEA labor analgesia was left to the discretion of the anesthesiologist working on the labor and delivery floor.
The duration of epidural analgesia was defined as the time from the completion of the injection of the total volume (20 mL) of the study solution until the parturient pressed the demand button of the PCEA infusion pump.
Hypotension, defined as a systolic blood pressure of <90 mm Hg or a 20% decrease from baseline, was treated immediately with a fluid bolus and IV ephedrine as required.
After the administration of the study solution, each parturient was evaluated by an investigator blinded to the study solution. Assessments were made every 2 min for the first 10 min, then every 5 min until 30 min, and finally every 15 min until additional epidural analgesic study solution was delivered by the PCEA device. Parturient appraisal included demographics, assessment of vital signs, continuous pulse oximetry, and completion of a 100-mm linear visual analog scale for pain (VASP) at the peak of contractions (0 = no pain; 100 = worst pain imaginable). At the same time intervals, somnolence was assessed by using a 4-point ordinal scale for degree of sedation (0 = wide awake; 1 = drowsy; 2 = rousable; 3 = nonrousable), and weakness of the lower extremities by using the 4-point Bromage scale. Side effects, such as nausea alone, nausea and vomiting, and pruritus, were also recorded. The ability of the patient to micturate spontaneously was also recorded. The level of sensory loss to cold (ice) along the midclavicular line was assessed 30 min after the completion of the administration of the study solution. On delivery of the baby or when additional PCEA analgesia was self-administered, the patient was no longer required to complete the VASP score.
Effective labor analgesia was defined as a VASP score of <20 mm at 20 min after complete administration of the study solution.
Adequacy of motor function for ambulation was assessed 30 min after the administration of the study solution by using a modified Bromage scale (1). Parturients were asked to demonstrate straight leg raises, then sit at the edge of the bed, stand, and finally perform a deep knee bend. Ambulation was considered possible after three unassisted steps. Parturients were permitted to ambulate only after they successfully demonstrated three unassisted steps and only when accompanied by a responsible care provider (i.e., labor nurse). Once the parturient returned to bed, these assessments were repeated before permitting subsequent ambulation.
All parturients had continuous electronic FHR monitoring for 30 min after the initiation of LEA. Either continuous or intermittent FHR monitoring was subsequently done at the discretion of the obstetric care team. Any FHR abnormalities identified by the blinded obstetric team were recorded. Duration of the first and second stages of labor and the requirement for an instrumented (forceps) or cesarean delivery were recorded. Management of labor was left to the discretion of the obstetric caregivers.
Medication failure or technical failure was assessed if analgesia was inadequate (VASP > 20 mm) at 20 min. Failures were defined as medication-related if a symmetric sensory level was detected despite inadequate analgesia. Failures were considered technical-related if the level was undetectable, asymmetric with one side T10, or patchy. Parturients identified with either medication or technical failures were excluded from further data collection but included in the final data analysis.
Data were expressed as mean ± SD and were analyzed by using independent t-tests for continuous data and 
2 and Fisher’s exact proportion tests for categorical and nominal data. A P < 0.05 was considered statistically significant.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Of the 40 women enrolled in the study, 20 were randomized to the BF group and 20 to the RF group. There were no statistical differences between the groups as to demographic characteristics, cervical dilation at the time the study solution was administered, or birth weight (Table 1).
|
The time to inject the entire study solution was similar in both groups (P > 0.05). No technical failures were encountered during the initiation of LEA.
There was no significant difference in the VASP scores immediately before the initiation of LEA between the two groups. One woman in the BF group required supplemental epidural study solution at 20 min because of a VASP score of > 20 but < 30, even though cutaneous sensory levels were >T10 bilaterally. This patient experienced a rapidly progressive labor and complained primarily of perineal pressure. Two women (one BF and one RF) reported VASP scores > 0 but < 20 at 20 min but did not request additional epidural study solution. Both women experienced rapidly progressive labors and complained primarily of perineal discomfort (pressure). All three women were excluded in the determination of study solution analgesic profile and time to VASP score = 0. In the remaining women, the VASP scores did not differ between 0 and 20 min after the injection of the study solution (Figure 1).
|
Mean time to VASP score = 0, mean duration of analgesia, and the mean PCEA volume per hour were not statistically different between the groups (Table 2).
|
A similar distribution of the highest level of cutaneous sensory loss to cold (ice) in the midclavicular line, was observed with women in both groups (Figure 2).
|
Hypotension was not observed in any parturients. The incidence of nausea and pruritus was similar between the two groups. One (BF) patient experienced an episode of nonreassuring FHR tracing described as decreased variability that did not require obstetric intervention.
Unassisted maternal ambulation was observed in all women of the RF group but only 75% (15 of 20) of the BF group (P < 0.03). Of the five women (BF) who were unable to ambulate, one was unable to successfully complete a straight-leg raise, and four were unable to complete the partial deep knee bend as a result of motor weakness. None of the women experienced postural hypotension.
There was no evidence of excessive somnolence or desaturation after the administration of either study solution. Maternal ability to micturate spontaneously was demonstrated by all women in the RF group but only by 65% (13 of 20) in the BF group (P < 0.05).
Labor characteristics and incidence of cesarean deliveries did not differ between the two groups; however, the occurrence of forceps deliveries was elevated in the BF group compared with the RF group (35% vs 10%, respectively; P < 0.04) (Table 3).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Reports of the use of dilute concentrations of bupivacaine combined with fentanyl to initiate LEA to further reduce motor blockade have been documented (3–6). The initiation of consistently effective LEA with minimal-to-no residual motor block using dilute concentrations of ropivacaine combined with fentanyl has not been reported. The results of this study indicate that 20 mL of both dilute concentrations of bupivacaine and ropivacaine combined with fentanyl provide equally effective epidural labor analgesia with no adverse maternal or fetal effects. This is the first report of the consistently effective initiation of LEA with dilute concentrations (0.08%) of either bupivacaine or ropivacaine combined with fentanyl.
The higher rate of unassisted ambulation is consistent with studies that have suggested less motor blockade associated with undiluted ropivacaine. This, however, is the first investigation to assess unassisted ambulation, considered the definitive assessment of lower limb motor strength (1).
The rate of spontaneous micturition was higher in the RF group. The mechanism for this observation requires further investigation. However, the ability of parturients to micturate spontaneously while receiving LEA has considerable cost implications, because of the reduction in the number of either intermittent catheterizations or continuous indwelling bladder catheters. Whether the reduced manipulation of the bladder significantly reduces the incidence of postpartum urinary tract infections requires further investigation.
Considering the routine practiced at our institution of maintaining LEA with a continuous epidural infusion (CEI) at 10–12 mL/h plus PCEA (5 mL; 10-minute lockout; no hourly limit), parturients in the present study received at least one-third less medication. These results concur with previous investigations (7–9) reporting that, with PCEA alone, analgesic requirements were reduced by approximately one-third to one-half compared with CEIs at 10–12 mL/h. Determinations of the optimal mode of delivery (PCEA versus CEI + PCEA) using dilute concentrations of these drugs merit further study.
Two recent publications suggested a difference in relative analgesic potency rather than chemical properties as the explanation for differences in both cardiotoxicity and motor blockade between bupivacaine and ropivacaine (10,11). These conclusions were based solely on the investigators’ determination of the concentration of 20 mL of each local anesthetic alone sufficient to initiate effective LEA in 50% of laboring parturients (MLAC). The MLAC, or 50% effective dose (ED50), of ropivacaine alone was reported to be 40% higher than for bupivacaine alone. Although these differences in ED50 might explain the observations of our investigation, the assertion that these local anesthetics are not equipotent based on determinations of the LEA ED50 (MLAC) requires critical appraisal. First, the full dose-response curves for LEA for both local anesthetics alone have yet to be determined. Consequently, it is possible that the 95% effective dose (ED95) of these drugs may, in fact, be similar, even though the ED50 values may be dissimilar. Although concentration response curves for each have been constructed (10), only the ED50 was actually measured. Thus, the curves were based primarily on derived estimates. Second, several similar investigations have indicated that the ED50 (MLAC) of epidural bupivacaine alone varies from 0.048% to 0.141% (6,10–14) suggesting that variations in study design may affect results. Third, we compared dilute concentrations of these local anesthetics in combination with fentanyl. There have been no dose-response determinations for either local anesthetic combined with fentanyl. Finally, the clinical relevance of ED50 (MLAC) determinations, without concurrent full dose-response curves remains suspect. In practice, only drug concentrations and combinations that provide labor analgesia with a minimum of ED95, are clinically relevant, and actually represent clinical potency. The concentration (0.08%) and combination with fentanyl (2 µg/mL) we used represents at least the ED95 of both drugs. Accepting for the moment the results of the ED50 (MLAC) investigations that bupivacaine is 40% more potent than ropivacaine, 0.048% bupivacaine and 2 µg/mL fentanyl should produce similar analgesic results. However, this concentration of bupivacaine, in fact, only produced effective analgesia in 50% of laboring parturients when combined with 2 µg/mL fentanyl (6). Moreover, Owen et al. (15) observed similar mean hourly use of either 0.125% bupivacaine or ropivacaine alone when administered by CEI and PCEA. This report concurs with our observation of an equivalent mean hourly PCEA utilization. Of note, our study design permitted precise parturient titration by not using a background CEI, as well as not limiting the hourly allowable dose. Further evidence of potential equipotency at clinically relevant doses was also provided by our observation of a similar mean duration of initial epidural analgesia. Although inequities in potency remain a possibility at the clinically relevant concentrations evaluated in the present investigation, the precise differences have yet to be determined.
The debate regarding the effect of ambulation (16,17) and LEA (18) on the progress of labor and labor outcome continues. The controversial report that LEA significantly slows the rate of cervical dilation during the first stage of labor and increases the cesarean delivery rate in nulliparous women in spontaneous labor has been highly publicized (19). In contrast, we observed rates of cervical dilation of 1.12 cm/h (BF) and 1.18 cm/h (RF), suggesting a lack of effect of LEA on the progress of labor. The observed mean duration of the second stage of labor (BF: 82 min; RF: 88 min) was less than that of 115 min previously reported (19). As well, cesarean delivery rates (BF: 5% vs RF: 10%) were also in contrast to the previous report of 25% (19). Our observations are of importance, as many of the nulliparous women enrolled had their labor induced (Table 3). Interestingly, the incidence of forceps delivery was significantly higher in the group receiving bupivacaine (35%) compared with those receiving ropivacaine (10%). The specific impact of ambulation and the method of LEA management we used requires further investigation.
In conclusion, the combination of ropivacaine (0.08%) and fentanyl (2 µg/mL) provides consistent, effective labor analgesia without causing clinically significant adverse maternal or fetal effects. This is the first report of dilute ropivacaine to initiate effective labor analgesia while preserving spontaneous micturition and unassisted ambulation of all evaluable parturients.
|
Footnotes |
|---|
DCC was awarded protected research time to complete this investigation from the Department of Anesthesiology, University of Saskatchewan.
Presented in part at the Society for Obstetric Anesthesia and Perinatology annual meeting, Denver, CO, May 21, 1999, and at the Canadian Society of Anesthesia annual meeting, Calgary, Alberta, Canada, June 21, 1999.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
-
Breen TW, Shapiro T, Glass B, et al. Epidural anesthesia for labor in an ambulatory patient. Anesth Analg 1993;77:919–24.
[Abstract/Free Full Text] - Murphy JD, Henderson K, Bowden MI, et al. Bupivacaine versus bupivacaine plus fentanyl for epidural analgesia: effect on maternal satisfaction. BMJ 1991;302:564–7.
- Scrutton MJL, Porter JS, O’Sullivan G. Comparison of three different loading doses to establish epidural analgesia in labour. Int J Obstet Anesth 1998;7:165–9.
- Price C, Lafreniere L, Brosnan C, Findley I. Regional analgesia in early active labour: combined spinal epidural vs epidural. Anaesthesia 1998;53:951–5.[Web of Science][Medline]
- Eldridge J, Russell R. Epidural loading-doses for primiparous women in labour: double-blind randomized comparison of 0.2% ropivacaine, 0.1% ropivacaine with 0.0002% fentanyl and 0.1% bupivacaine with 0.0002% fentanyl [abstract]. Int J Obst Anesth 1998;7:204.
-
Lyons G, Columb M, Hawthorne L, Dresner M. Extradural pain relief in labour: bupivacaine sparing by extradural fentanyl is dose dependent. Br J Anaesth 1997;78:493–7.
[Abstract/Free Full Text] -
Ferrante FM, Rosinia FA, Gordon C, Datta S. The role of continuous background infusions in patient-controlled epidural analgesia of labor and delivery. Anesth Analg 1994;79:80–4.
[Abstract/Free Full Text] - Gambling DR, Huber CJ, Berkowitz J, et al. Patient-controlled epidural analgesia in labour: varying bolus dose and lockout interval. Can J Anaesth 1993;40:211–7.[Web of Science][Medline]
- Lysak SZ, Eisenach JC, Dobson CE. Patient-controlled epidural analgesia during labour: a comparison of three solutions with a continuous infusion control. Anesthesiology 1990;72:44–9.[Web of Science][Medline]
- Polley LS, Columb MO, Naughton NN, et al. Relative analgesic potencies of ropivacaine and bupivacaine for epidural analgesia in labor: implications for therapeutic indexes. Anesthesiology 1999;90:944–50.[Web of Science][Medline]
-
Capogna G, Celleno D, Fusco P, et al. Relative potencies of bupivacaine and ropivacaine for analgesia in labour. Br J Anaesth 1999;82:371–3.
[Abstract/Free Full Text] - Columb MO, Lyons G. Determination of the minimum local analgesic concentrations of epidural bupivacaine and lidocaine in labor. Anesth Analg 1995;81:883–7.
- Polley LS, Columb MO, Wagner DS, Naughton NN. Dose-dependent reduction of the minimal local analgesic concentration of bupivacaine by sufentanil for epidural analgesia for labor. Anesthesiology 1998;89:626–32.[Web of Science][Medline]
-
Capogna G, Celleno D, Lyons G, et al. Minimum local analgesic concentration of extradural bupivacaine increase with progression of labour. Br J Anaesth 1998;80:11–3.
[Abstract/Free Full Text] - Owen MD, D’Angelo R, Gerancher JC, et al. 0.125% ropivacaine is similar to 0.125% bupivacaine for labor analgesia using patient-controlled epidural infusion. Anesth Analg 1998;86:527–31.[Abstract]
-
Bloom SL, McIntire DD, Kelly MA, et al. Lack of effect of walking on labor and delivery. NEJM 1998;339:76–9.
[Abstract/Free Full Text] - Albers LL, Anderson D, Craigin L, et al. The relationship of ambulation in labor to operative delivery. J Nurse-Midwifery 1997;42:4–8.[Web of Science][Medline]
-
Halpern SH, Leighton BL, Ohlsson A, et al. Effect of epidural vs parenteral opioid analgesia on the progress of labor. JAMA 1998;280:2105–10.
[Abstract/Free Full Text] - Thorp JA, Hu DH, Albin RM, et al. The effect of intrapartum epidural analgesia on nulliparous labor: a randomized, controlled, prospective trial. Am J Obstet Gynecol 1993;169:851–8.[Web of Science][Medline]
This article has been cited by other articles:
|
|
 |
|
  S. H. Halpern and B. Carvalho Patient-Controlled Epidural Analgesia for Labor Anesth. Analg., March 1, 2009; 108(3): 921 - 928. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Beilin, N. R. Guinn, H. H. Bernstein, J. Zahn, S. Hossain, and C. A. Bodian Local Anesthetics and Mode of Delivery: Bupivacaine Versus Ropivacaine Versus Levobupivacaine Anesth. Analg., September 1, 2007; 105(3): 756 - 763. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. B. Lee, W. D. Ngan Kee, F. F. Ng, T. K. Lau, and E. L. Y. Wong Epidural Infusions of Ropivacaine and Bupivacaine for Labor Analgesia: A Randomized, Double-Blind Study of Obstetric Outcome Anesth. Analg., April 1, 2004; 98(4): 1145 - 1152. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Senard, A. Kaba, M. J. Jacquemin, L. M. Maquoi, M.-P. N. Geortay, P. D. Honore, M. L. Lamy, and J. L. Joris Epidural Levobupivacaine 0.1% or Ropivacaine 0.1% Combined with Morphine Provides Comparable Analgesia After Abdominal Surgery Anesth. Analg., February 1, 2004; 98(2): 389 - 394. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Frenea, C. Chirossel, R. Rodriguez, J.-P. Baguet, C. Racinet, and J.-F. Payen The Effects of Prolonged Ambulation on Labor with Epidural Analgesia Anesth. Analg., January 1, 2004; 98(1): 224 - 229. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J.-M. Bernard, D. Le Roux, and J. Frouin Ropivacaine and Fentanyl Concentrations in Patient-Controlled Epidural Analgesia During Labor: A Volume-Range Study Anesth. Analg., December 1, 2003; 97(6): 1800 - 1807. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. W. Hollmann, K. Kurz, S. Herroeder, D. Struemper, K. Hahnenkamp, N. S. Berkelmans, C. G. den Bakker, and M. E. Durieux The Effects of S(-)-, R(+)-, and Racemic Bupivacaine on Lysophosphatidate-Induced Priming of Human Neutrophils Anesth. Analg., October 1, 2003; 97(4): 1053 - 1058. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. R. Connelly, R. K. Parker, T. Pedersen, T. Manikantan, T. Lucas, S. Serban, M. El-Mansouri, S. DuBois, E. D. Santos, A. Rizvi, et al. Diluent Volume for Epidural Fentanyl and Its Effect on Analgesia in Early Labor Anesth. Analg., June 1, 2003; 96(6): 1799 - 1804. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. S. Polley and M. O. Columb Ropivacaine and Bupivacaine: Concentrating on Dosing! Anesth. Analg., May 1, 2003; 96(5): 1251 - 1253. [Full Text] [PDF]
|
|
|
|
|
|
S. H. Halpern and V. Walsh Epidural Ropivacaine Versus Bupivacaine for Labor: A Meta-Analysis Anesth. Analg., May 1, 2003; 96(5): 1473 - 1479. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Landau, E. Schiffer, M. Morales, G. Savoldelli, and C. Kern The Dose-Sparing Effect of Clonidine Added to Ropivacaine for Labor Epidural Analgesia Anesth. Analg., September 1, 2002; 95(3): 728 - 734. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. J. Clement, L. Caruso, F. Lopez, F. Broisin, M. Blanc-Jouvan, E. Derre-Brunet, A. Thomasson, G. Leboucher, and J. P. Viale Epidural analgesia with 0.15% ropivacaine plus sufentanil 0.5 {micro}g ml-1versus 0.10% bupivacaine plus sufentanil 0.5 {micro}g ml-1: a double-blind comparison during labour Br. J. Anaesth., June 1, 2002; 88(6): 809 - 813. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. R. Connelly, R. K. Parker, T. Lucas, M. El-Mansouri, V. Komanduri, P. Nayak, S. Gutta, C. Gibson, and S. M. Dunn The Influence of a Bupivacaine and Fentanyl Epidural Infusion After Epidural Fentanyl in Patients Allowed to Ambulate in Early Labor Anesth. Analg., October 1, 2001; 93(4): 1001 - 1005. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. B. Whiteside and J. A. W. Wildsmith Developments in local anaesthetic drugs Br. J. Anaesth., July 1, 2001; 87(1): 27 - 35. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. O. Columb, L. S. Polley, and D. C. Campbell Potencies and Probabilities: One-Sided P Values Suggest a One-Sided Story! Anesth. Analg., January 1, 2001; 92(1): 278 - 279. [Full Text] [PDF]
|
|
|
|
|
|
W. Gogarten and H. Van Aken A Century of Regional Analgesia in Obstetrics Anesth. Analg., October 1, 2000; 91(4): 773 - 775. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
