Analgesic Efficacy of Two Concentrations of Bupivacaine in Women in Labor
Condition: Obstetric Pain
MeSH terms: Labor Pain
Study type: Interventional
Phase: Phase 4

Summary: 
      Abstract.

      Epidural analgesia is the most safe and effective for the treatment of pain of childbirth
      method. Epidural Bupivacaine provided excellent analgesia for labor and remains the most
      widely used local anesthetic in obstetric anesthesia.

      Objective: To evaluate the analgesic efficacy of two concentrations of bupivacaine in women
      in labor.

      Methods: 114 patients were included in labor with term pregnancy. Were grouped randomly into
      two groups: patients who received bupivacaine 0.125 % (Group A) and 0.25% bupivacaine (group
      B). Patients in group A received 10 ml of 0.125% bupivacaine bolus. The patients in group B
      received 10 ml. Bupivacaine 0.25% bolus. Pain intensity according to VAS, blood pressure,
      heart rate, respiratory rate, degree of motor block was assessed using the Bromage scale at
      different periods of time.

      Results: Demographic characteristics and parity were compared, no statistically significant
      differences. By comparing the values of the VAS measure 0, 15, 30, 60 and 90 minutes into
      statistically significant differences in favor of the group with 0.25% Bupivacaine with
      decreased pain perception after 30 minutes, p-value found 0.02. No differences in arterial
      pressure, heart rate and respiratory rate were found between the two groups.

      Conclusion: The concentration of 0.25% Bupivacaine has greater analgesic efficacy compared
      with 0.125% bupivacaine.
    

Detailed description: 
      Registration number 2013-2301-21 by Local Committee on Ethics in Health Research and the
      Mexican Institute of Social Security General Hospital Zone 03. The investigators conduct the
      study at the Hospital General Regional No. 17 in cancun, Quintana Roo. México. At time in
      which the obstetrician determined active phase labor and requested obstetric analgesia,
      patients randomly to one of two study groups being the group A which was administered 0.125%
      bupivacaine and group B was administered 0.25 % bupivacaine, informed consent for the study
      was collected.

      Blood count, glucose, urea, creatinine and clotting times in the third trimester were
      included. Preoperative coagulation tests in patients without underlying disease, are
      expendable if clinical signs of hemorrhage are discarded.

      The investigators were masking the patient. The patient was asked for which analgesia
      bupivacaine unknown concentration that was applied to control the bias of the patient.

      Investigators were asking the applicator. One of the researchers selected from a randomized
      list containing pages in both groups with numbers ranging from 0001 to 0114 with 57 subjects
      for each group and these numbers selected were prepared in sterile form and start the day in
      the morning, the amount of 10 ml syringes with foil for each mixture. Ten analgesics were
      preparing during the day, those not performed bupivacaine were discarded, and the new day
      preparations were made.

      Standardization of the technique and applicator. All anesthesiologists who participated in
      the study were given a written description of the anesthetic technique used to standardize
      procedures and avoid bias in the methodology of implementation.

      Prior to performing the technique 500 ml of Ringer lactate was infused. Epidural Block (BP)
      measurement was performed and performed a non-invasive monitoring of heart rate and oxygen
      saturation monitor electronically. Which were recorded on the data collection sheet designed
      for this study.

      The patient was placed in the left lateral position with knees flexed (fetal position) or
      sitting. anesthesiologist used surgical clothes, cap and surgical masks, performed surgical
      handwashing and used sterile gloves and sterile gown and performed surgical toilet of the
      lumbar back region with iodine solution and sterile drapes were placed delimiting the
      selected area. Puncture was performed at the level of the L2- L3 with a needle of 17 gauge
      tuohy -Weiss . Epidural space The search was performed using the technique of loss of
      resistance to air. The catheter was inserted and left inserted 3-4 cm into the epidural
      space; was aspirated with a syringe of 3 ml and was determined not to leave blood or
      cerebrospinal fluid. Sterile prefilled syringe medication to the anesthesiologist who
      performed the procedure was given; which were injected with either a dose of 10 ml with the
      corresponding concentration according to the group to which he belonged. Group A or 0.125%
      bupivacaine dose of 10 ml and group B of 0.25 % bupivacaine. Catheter is firmly fixed to the
      skin, to prevent their displacement with tape, leaving sealing the proximal end of the
      epidural catheter. Sensory level as measured by thermal sensitivity this is done with closed
      eyes of the patient, two test tubes filled, one with cold 5 water use - 10 ° C, and one with
      hot water at 40-45 ° C, the skin touched the bottom of the tube for more than 3 seconds and
      was asked to identify the patient saying "cold" or "hot". The region was delimiting with
      sensory block from zone to zone without blocking lock.

      Blocking engine if there was assessed using the modified Bromage scale. which was performed
      by asking the patient to move his legs or feet and motor block grades were classified as
      null, partial, complete or almost complete; purposes of numerical comparison gave these
      categories numbers 0, 1, 2, 3 respectively, where (0) is normal movement of legs and feet
      (zero ), 1 the patient is able to flex knees with normal movement of feet (part), 2 Unable to
      flex knees, but with normal foot movement (almost complete ), 3 Unable to move legs or feet
      (full).

      A applied 15 minutes of analgesia again recorded vital signs and note the analgesic level
      were taken by Visual Analog Scale (VAS), by the responsible investigator which collected the
      data.

      Values Blood Pressure Media (TAM ) < 60mmHg presented the infusion of ringer lactate solution
      at 5 ml / kg bolus and increase of 5 mg ephedrine was administered iv.

      The measurement of the variables involved in the preanalgesia and at 15, 30, 60 and 90
      minutes after drug administration were registered.

      Variables were measured: Vital signs (blood pressure, heart rate, respiratory rate),
      sensitive metameric level, engine Block, degree of analgesia according to the VAS.

      It was performed according to the following. Metameric sensory level: No blocking, below
      umbilicus (< T10), between the navel and xiphoid appendix him (T10 - T6), above the xiphoid
      (> T6). Motor block: 0: can lift both legs straight, 1: You can bend the knee and move your
      feet, 2: You can only move your feet, 3: You cannot move the lower extremities.

      VAS: value between 0 and 10 control / time. 0: no pain 10: Maximum pain imaginable. It was
      determined by visual analog scale of 0 to 10 cm. Considering effective analgesia according to
      centimeters decrease from baseline or pre VAS analgesia. Optimal reduction of the initial 4
      cm, enough to decrease 3 cm, good with decrease of 2 cm, zero with reduced or unchanged 1cm .

      If no analgesic efficacy with VAS valuation at 15 minutes, 5 ml was administered. Mixture
      used over bupivacaine 0.25% or 0.125 and would restart measurement variables with the set
      times at 15, 30, 60 and 90 minutes, taking as required for registration and validity of the
      study variables measuring at least 3 times, if delivery occurs before the scheduled time.

      91 minutes was terminated measuring pain analysis records, and records of completion delivery
      was taken.

      Building a database was performed and the statistical program SPSS version 20.0 for Windows 7
      was used and proceeded to perform the statistical analysis of data

      Analgesic efficacy according to the result of the measurement of the visual analog scale
      (VAS), according to the result of the evaluation of this scale which is expressed in a
      numerical value was determined, estimates of frequency measurement were performed, measures
      dispersion and central tendency for each variable. Comparison of sociodemographic variables
      (age, number of pregnancy, previous cesarean sections and previous births) and clinical (mild
      pain, moderate pain, severe pain) that were generated was performed using Student's t test
      for independent samples, and X2 and trend in the case of nominal variables. To compare
      differences in variables in blood pressure, heart rate and respiratory rate, EVA, ANOVA for
      repeated samples was performed.
    

Intervention name(s): bupivacaine
Intervention type(s): Drug
Intervention description(s): At the beginning of the work of effective labor maneuver randomly be allocated ( using sealed envelopes) and an outsider to the study prepared the dosage to bupivacaine 0.125% or 0.25% to be administered by epidural catheter for an anesthesiologist to disown the concentration employed. It is measured vital signs, and visual analogue scale dilatation in minutes 0,15,30,60 and 90 after being applied analgesia.
Other intervention name(s): Bupivacaine 0.125%; Bupivacaine 0.25%
Intervention MeSH terms: Bupivacaine
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: Double (Participant, Care Provider)
Primary purpose: Supportive Care
Keywords: obstetric pain, bupivacaine, analgesic efficacy