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Labor Analgesia

Labor Analgesia. Katy Kemnetz. Labor analgesia.

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Labor Analgesia

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  1. Labor Analgesia Katy Kemnetz

  2. Labor analgesia “Labor causes severe pain for many women. There is no other circumstance where it is considered acceptable for an individual to experience untreated severe pain, amenable to safe intervention, while under a physician's care. In the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief during labor.... None of the techniques appears to be associated with an increased risk of cesarean delivery.” -ACOG committee opinion 339

  3. Patient education • A woman's satisfaction with her labor and delivery are less dependent on the amount of pain and more dependent on her involvement in the decision-making process • Obstetricians should educate their patients early in pregnancy about their options

  4. Stages of labor • First stage • Visceral pain caused by contractions, stretching of cervix and uterus, ischemia • Fibers from uterine body and fundus enter spinal cord at T10-L1 with sympathetics • Fibers from cervix and upper vagina enter cord at S2-S4 with parasympathetics • Second stage • Add somatic pain from stretching of vaginal, perineum, and pelvic ligaments • Travels to spinal cord in S2-S4 via pudendalnerve

  5. Distribution/intensity of labor pain T11/T12 dermatomes Lower back and perineum Perineum T10/L1 dermatomes

  6. Adverse consequences of pain • Stress • Release of catecholamines can reduce placental blood flow • Hyperventilation • Impaired transfer of oxygen to fetus • Impaired maternal hemoglobin dissociation • Placental vasoconstriction • Psychological • PTSD and postpartum depression

  7. Systemic labor analgesics • Options • Opioids • Morphine, fentanyl, meperidine, hydromorphone • Mixed opioid agonist-antagonists • Nalbuphine, butorphanol • Dose ceiling effect for respiratory depression • PCA • Cons • Less effective analgesia • Risk of respiratory depression, nausea, vomiting, sedation, decrease in FHR variability • Pros • Result in shorter duration of labor and less oxytocin augmentation

  8. Local blocks • Pudendal block • Somatic pain of stretching of vagina/cervix/perineum • Ineffective for pain of contractions • Para cervical block • Blocks some uterine, cervical sensory fibers • Somewhat effective for contractions • ?Effect on fetus

  9. Contraindications to neuraxial analgesia • Patient refusal • Uncorrected coagulopathy • Infection of the lower back • Uncorrected hypovolemia • Increased intracranial pressure

  10. Epidural analgesia The epidural space is bounded anteriorly by the posterior longitudinal ligaments, laterally by the pedicles and intervertebral foramina, and posteriorly by the ligamentumflavum. Contents of the epidural space include the nerve roots that traverse it from foramina to peripheral locations, fat, areolar tissue, lymphatics, and blood vessels

  11. Epidural anesthesia • A catheter is placed in the epidural space and left there for the duration of labor • Slower onset of anesthesia (5-10 minutes) but longer duration • Usually an epidural includes a combination of opioid(fentanyl/ sufentanyl) and local anesthetic (bupivicaine/ ropivacaine) • Ephinephrineand opioids reduce concentration of local anesthesia required • A lower concentration of local anesthetic reduces the motor blockade (“walking epidural”) • Dosing regimens: • Intermittent dosing • Breakthrough pain • Continuous infusion • Increased risk of motor blockade • PCEA • Lower total dose of analgesics used during labor and lower incidence of motor block

  12. Spinal and Combined Spinal-Epidural (CSE) • Spinal analgesia has quicker onset (within 5 minutes) but shorter duration (90 minutes) • Catheter is not left in intrathecalspace • More useful for planned c-section, less useful for labor • Combined spinal epidural is best for quick onset and long duration • Greater risk of pruritis, fetal bradycardia, maternal hypotension with higher doses • Minimized by using lipophilicopioids like fentanyl in intrathecal space • No change in rate of cesarean section

  13. Second stage of labor • May have to discontinue epidural if motor block is preventing pushing

  14. Third stage of labor • If there is a complication with delivery and patient does not have neuraxial analgesia, may have to administer general anesthesia • Shoulder dystocia • Emergent cesarean section • Considerations for general anesthesia • More difficult intubation • Higher aspiration risk • Shorter lasting preoxygenation • Risk of fetal depression

  15. Adverse effects of labor analgesia • Systemic toxicity (inadvertent injection into blood vessel) • CNS (tinnitus, seizures) and cardiovascular • High spinal • Aspiration, dyspnea, hypotension • Hypotension (w/ decreased placental perfusion) • Failed block • Pruritis, nausea, vomting, backache, urinary retention • Postdural puncture headache (decreased with pencil point spinal needles) • Respiratory depression, epidural hematoma, infection • Effects on fetus: hypotension; if not, then increased placental flow, improved fetal acid/base status. Fetal bradycardia 2/2 uterine hypertonus 2/2 opioids • Association with cesarean delivery and instrumental delivery but no causation

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