Patient-Controlled Epidural Analgesia for Labor

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Patient-Controlled Epidural Analgesia for Labor

• Obstetric Anesthesiology(Anesth Analg
  20091089218)
• 
  R2 ? ? ?

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• patient-controlled epidural analgesia(PCEA) for
  labor
• Gambling et al.1 in 1988
• PCEA vs continuous epidural infusion (CEI)
• 1. analgesia similar
• 2. PCEA reduces the incidence of unscheduled
  clinician interventions
• 3. total dose of local anesthetic ??
• 4. reduces the incidence of lower extremity
  motor block
• 5. no clinically significant impact on
  obstetric or neonatal outcomes

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• Clinical research has focused on refining PCEA
  techniques
• 1. further improve analgesia
• 2. reduce motor block
• 3. increase maternal satisfaction
• 4. reducing the frequency of unscheduled
  clinician interventions
• 1) Should a background infusion be used?
• 2) Is ropivacaine superior to bupivacaine when
  used for PCEA in labor?
• 3) Can the volume of the PCEA bolus dose and
  lockout interval be manipulated to optimize
  analgesia?
• 4) What is the impact of new techniques and
  technologies on current PCEA practice?

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THE USE OF BACKGROUND INFUSION

• seven studies PCEA with and without background
  infusions
• the infusion rates quite low, with most lt5
  mL/h.
• one study found a difference in analgesia
• without a background infusion ? a higher
  incidence of intense pain (gt4/10)
• all of these studies Significant motor block
  was uncommon
• Two studies more clinician interventions in the
  no infusion group.
• One study more local anesthetic in the no
  infusion group
• maternal satisfaction no differences

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• summary
• background infusion
• 1. reduces the incidence of unscheduled
  clinician interventions
• 2. improve patient analgesia
• 3. no increase in motor block associated with
  the background infusion.

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ROPIVACAINE VS BUPIVACAINE

• 11 studies
• wide range of PCEA settings.
• Bupivacaine 0.05 0.125.
• Ropivacaine 0.05 0.20.
• Two studies used different concentrations
• ? reflect differences in
  potency
• five studies bupivacaine ? increased incidence
  of motor block
• However, most studies did not account for
  relative differences in potency between
  ropivacaine and bupivacaine
• Halpern et al Maternal satisfaction
• mobility - ropivacaine group
• analgesia at delivery - bupivacaine group
• Fischer et al.
• relief of contraction and delivery pain in
  bupivacaine

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• Summary
• both ropivacaine and bupivacaine
• well suited for PCEA in labor.
• an increased incidence of motor block in
  bupivacaine
• but this difference may not be clinically
  significant,
• particularly for short labors.
• Flexibility in the PCEA settings may offset any
  advantage that drug selection may have.

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BOLUS DOSE VOLUME AND LOCKOUT INTERVAL

• Six studies compared various PCEA settings
  try to determine the ideal bolus dose and
  corresponding lockout time interval
• Analgesia, maternal satisfaction, motor block,
  and clinician rescue boluses were reported in all
  of the studies.
• bupivacaine (0.06250.125) and ropivacaine
  (0.10.2) with fentanyl or sufentanil.
• Bolus volumes ( 2 20 mL ) , lockout intervals
  (5 30 min)

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• Three studies used a background infusion
• Bernardet al
• Group 1 bolus 4 mL, lockout 8 min
• Group 2 bolus 12 mL, lockout 25 min
• Significantly better analgesia in
  Group 2
• All study
• no significant difference in unscheduled
  clinician interventions
• Significant motor block was uncommon
• no reports of toxicity or increased side
  effects with the larger bolus volumes

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• Summary
• no ideal bolus dose or lockout interval setting
  for labor PCEA
• Large bolus doses of dilute local anesthetic
• ? superior analgesia and maternal satisfaction

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DRUG CONCENTRATION

• Six studies
• three studies The more concentrated solution
  groups
• ? significantly greater motor block
• Two studies less pruritus with local anesthetic
  without opioids
• use of dilute local anesthetic solutions with
  opioids for labor PCEA
• ? less local anesthetic consumption
• ? less motor block without compromising
  labor analgesia
• more dilute solutions also used larger volumes
• ? improve analgesia
• ? more uniform anesthetic spread in the epidural
  space
• addition of lipophilic opioids to local
  anesthetics
• ?reduction in the minimum local analgesic
  concentration of bupivacaine
• ?improves the quality of analgesia
• but, lipophilic opioids? dose dependent pruritus

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• summary
• labor PCEA dilute local anesthetic solutions
  should be used.
• The use of 0.25 bupivacaine and 0.2
  ropivacaine
• increased incidence of motor blockade
  without concomitant
• increases maternal analgesia or
  satisfaction.
• avoid excessive pruritus
• ? The lowest, clinically effective,
  concentration of lipophilic
• opioid should be added

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FUTURE DEVELOPMENTS

• Computer-Integrated PCEA
• automatically adjusts the background infusion
  rate based on the number of PCEA demands
• adjusts the background infusion to 5, 10, or 15
  mL/h If the patient require one, two, or three
  demand boluses
• decreases the background infusion by increments
  of 5 mL/h if there are no bolus demands in the
  previous hour
• improve efficacy while minimizing increases in
  local anesthetic use-associated background
  infusions
• had similar local anesthetic consumption compared
  with demand-only PCEA but was associated with
  increased maternal satisfaction
• not currently commercially available

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• Programmed Intermittent Mandatory Epidural
  Boluses
• (PIEB)
• Same total hourly amount of local anesthetic is
  administered as intermittent boluses
• (e.g., two boluses of 6mL every 30 min vs
  12 mL/h CEI)
• more effective for labor analgesia
• -similar analgesia
• -higher maternal satisfaction
• -less need for unscheduled clinician rescue
  boluses
• the local anesthetic-sparing effect of PIEB
• ? more uniform epidural spread of local
  anesthetics when large volumes of local
  anesthetic
• reduced consumption of ropivacaine and less PCEA
  demand boluses while maintaining similar
  analgesic efficacy
• currently not available

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• Disposable Epidural PCEA
•  
• simple disposable PCEA vs standard electronic
  PCEA device
• no significant differences in analgesic efficacy,
  maternal satisfaction, local anesthetic use, or
  side effects
• less bulky, may facilitate ambulation during
  labor
• disadvantages the lack of programmability and
  potentially increased costs.
•  

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SUMMARY

• PCEA-reliable and effective method
• Low concentrations of bupivacaine or ropivacaine
  with opioids
• ? excellent analgesia
• using dilute local anesthetic solutions (up to
  0.125 bupivacaine or 0.2 ropivacaine) ? Motor
  block can be minimized
• Background infusion
• ? reduces the need for unscheduled clinician
  interventions
• ? better analgesia
• Background infusion rates ( 2 10 mL/h)
  effectively
• no ideal bolus dose or lockout interval setting
  for labor PCEA
• Larger bolus doses (more than 5 mL) of dilute
  local anesthetic
• superior analgesia