labor%20pain
LABOR PAIN
Labor pain experience is highly individualized and will depend on a woman's emotional, motivational, cognitive, cultural and social circumstances.
There is no other circumstance where it is considered acceptable for a patient to experience severe pain that is amenable to safe intervention while under a physician's care.
The pain felt during the 1st stage of labor originates from the rhythmic contractions of the lower uterine segment and progressive cervical dilation mediated via T10-L1 spinal nerves.
The pain in the 2nd stage of labor is more intense due to stretching of the vagina, vulva and perineum as the fetus descends in the birth canal superimposed by the pain of uterine contractions, and is transmitted through the S2-S4 spinal segments.

Patient's Decision

  • Maternal request should be sufficient justification to provide pain relief during labor
    • Selected analgesia technique will depend on the patient’s wishes, medical status, progress of labor and facility resources
  • Analgesia and anesthesia should be provided only by competent practitioners who can perform perianesthetic evaluation, supervise management of analgesia and treat obstetric complications that may arise
    • Access to facilities where resuscitation equipment and drugs are immediately available
  • Depending on the woman’s wishes and available resources, pain management is usually a combination of non-pharmacological and pharmacological methods
  • Safe and effective pain relief choices should be given to the mother that allow for individualization, flexibility and adequate pain relief that take into consideration her psychosocial needs

Pharmacotherapy

Systemic Analgesia

Inhalational Analgesia

Nitrous Oxide

  • Consists of a 50:50 mixture of nitrous oxide and oxygen (O2)
    • It is usually self-administered through a face mask or mouthpiece as needed but can be administered continuously with medical supervision
    • Patient should know how to inhale the mixture correctly so that peak brain nitrous oxide concentration coincides with the peak contraction pain
  • Effects:
    • Provides pain relief within 20-30 seconds of inhalation
    • Does not appear to interfere with labor physiology
    • Intermittent use of nitrous oxide is safe for the mother and fetus, though the mother may feel lightheaded and nauseous 
  • Risk of maternal hypoxemia may be increased by concomitant use of systemic opioids
  • Scavenging equipment is needed to avoid contamination of the environment

Sevoflurane

  • Newer agent with more rapid onset and offset of analgesia
  • Studies showed higher pain relief and sedation scores as compared to nitrous oxide

Parenteral Opioids

  • Widely used as 1st-line labor pain medication especially in settings where epidural anesthesia is not available
  • Commonly employed parenteral opioids include Butorphanol, Pethidine and the short-acting, lipid-soluble Fentanyl
    • The use of Morphine has declined due to greater respiratory depression when compared with the newer agents
  • Effects: Do not provide as much pain relief as epidural analgesia but provide shorter 1st and 2nd stages of labor, fewer fetal malpositions and fewer instrumental vaginal deliveries
  • Can cause fetal side effects because it can freely cross the placental barrier
    • May cause neonatal respiratory depression, decreased alertness, sucking inhibition, lower neurobehavioral scores, and delay in effective feeding
    • Risk of neonatal respiratory depression depends on the dose and timing of maternal opioid administration
  • Close monitoring and O2 are required with ready access to Naloxone, which is an opioid antagonist
  • Opioids may interfere with breastfeeding after delivery 

Patient-Controlled Intravenous (IV) Opioid Analgesia

  • Patient controls the analgesia which provides superior pain relief with smaller doses, thus has lower incidence of side effects
  • An antiemetic may be given to the patient if an IV or IM opioid is used 

Regional Analgesia 

  • Gives better pain relief than opioids without long-term backache but is associated with longer duration of 2nd stage of labor and a higher chance of instrumental birth, eg vacuum- or forceps-assisted vaginal deliveries 
    • Should be provided in facilities equipped for instrumental delivery or cesarean section
  • Does not increase 1st stage of labor duration or possibility of cesarean delivery in nulliparous women undergoing labor induction
  • May be given to women with severe pain during the latent 1st stage of labor  
  • In the 2nd stage of labor, Oxytocin should not be used routinely  
  • Patient's mobility may be decreased due to intensive IV access and level of monitoring

Neuroaxial Analgesia

  • Provides a superior level of pain relief during labor when compared with systemic drugs
    • The gold standard for labor pain management
  • Main goal is to give adequate pain relief with minimal motor blockade
  • Appropriate resources for treating complications should be available
    • IV infusion should be started prior to initiation and be maintained throughout the duration of the neuraxial analgesia or anesthesia
    • Monitor fetal heart rate (HR) before and after the administration of regional analgesia
  • Advantages:
    • Provides complete analgesia
    • Does not cause maternal or neonatal sedation
    • Allows mother to participate during delivery
    • Alleviates harmful reflex responses to pain
    • May change continuous analgesia to surgical anesthesia for emergency cesarean (CS) section
      • General anesthesia and its risk for airway problems are prevented
  • Disadvantages:
    • Needs a skilled anesthesiologist
    • Occasional unsuccessful block occurs
    • May cause sympathectomy which leads to maternal hypotension and decreased uteroplacental perfusion
    • May prolong 2nd stage of labor and increase instrumental vaginal delivery
  • Contraindications:
    • Patient refuses
    • Pre-existing coagulopathy or mothers taking anticoagulants
    • Infection at the puncture site
    • Lack of experienced anesthesiologists
    • Hemorrhage or other causes of hypovolemia
    • Untreated systemic infection
    • Preload-dependent disease states
    • Pathology in the lumbar spine
    • Increased intracranial pressure

Lumbar Epidural Analgesia

  • Commonly employed technique in the 1st and 2nd stages of labor, does not produce drug-induced depression in the fetus or mother
  • Anesthesia is administered into the epidural space through an indwelling plastic catheter
  • After the initial bolus, analgesia is maintained with intermittent bolus injection, continuous infusion, or patient-controlled epidural analgesia (PCEA) until after delivery or when there is no further need for analgesia/anesthesia
    • Continuous epidural infusion causes lower need for bolus injection and increases patient satisfaction, but higher total dose compared to intermittent injection
    • PCEA allows continuous epidural infusion and patient-titrated bolus injection resulting in greater patient satisfaction and lower average hourly dose of anesthesia, thus less motor blockade
  • Dose will depend on the intensity and location of the pain which is related to the amount and rate of cervical dilation; strength, frequency, and duration of uterine contractions; along with the position of the fetus at the time epidural analgesia is requested
    • Low-dose epidural analgesia is preferred over high dose as it promotes mobility in labor 
  • The addition of opioid to a low concentration of local anesthesia may improve analgesia and minimize motor block
    • If opioids are used, monitor for related complications (eg nausea, pruritus, respiratory depression)
  • Epidural labor analgesia for >6 hours increases the likelihood of maternal fever
    • This may be due to increased heat production, decreased heat loss, or changes in temperature regulation

Combined Spinal-Epidural Analgesia (CSE)

  • Administration of an intrathecal opioid injection prior to continuous epidural infusion
  • Has more rapid onset of pain relief compared to epidural analgesia
  • Provides more complete analgesia for women whose labor is progressing rapidly or in advanced stages of labor and for whom sacral analgesia is an important component of successful neuroaxial analgesia
  • May be used as a single anesthetic in patients who are about to give birth within 2-3 hours after receiving the medication
  • It may reduce the incidence of failed epidural analgesia
  • Disadvantages:
    • May cause spinal headache due to the need of dural puncture but not higher than in epidural analgesia
    • Pruritus is more common
    • Not suitable in the presence of nonreassuring fetal HR pattern or anticipated difficult airway because it is uncertain for 1-2 hours whether the epidural catheter is functional
    • Parturients are able to walk because of minimal motor blockade, but limited due to the need for continuous fetal monitoring after epidural placement

Single-Shot Spinal Analgesia

  • Provides pain relief that is effective in the 1st and 2nd stages of labor but time-limited in patients anticipating vaginal delivery
  • Has better analgesia than parenteral analgesics
  • Used in some hospitals where epidural analgesia is not available

Drugs for Neuraxial Labor Analgesia

  • Ideal analgesic should provide the fastest pain relief with minimal motor blockade and risk of maternal toxicity, and with very minimal effect on the uterine activity and uteroplacental perfusion
  • Neuraxial local anesthetics and opioids act synergistically to provide neuraxial analgesia
  • Combined use of local anesthesia and lipid-soluble opioid permits the use of lower doses of each drug, thus reducing unwanted effects
    • Local anesthetic dose needed for effective epidural analgesia without an opioid is associated with a higher incidence of motor blockade
    • High doses of epidural opioid, when used alone, are necessary for satisfactory pain relief but are associated with significant adverse effects

Local Anesthetics

  • Bupivacaine
    • Standard local anesthetic for epidural labor analgesia
    • Most often combined with Fentanyl or Sufentanil to induce epidural and CSE analgesia
    • with minimal placental transfer because it is highly protein bound
    • Effect of pain relief is 2 hours
  • Levobupivacaine
    • Less cardiotoxic and motor blockade than Bupivacaine
    • Onset and duration of action are the same as with Bupivacaine and Ropivacaine
  • Lidocaine and Chloroprocaine
    • Shorter latencies than Bupivacaine
    • with short duration of action limiting their use in labor analgesia
    • Lidocaine has a higher umbilical/maternal vein ratio because it is less protein bound
  • Ropivacaine
    • A homologue of Bupivacaine with similar latency and duration of action but has less potential for cardiac toxicity

Opioids

  • Fentanyl
    • Drug of choice for patients in active labor due to its short duration of action (60-90 minutes), which decreases risk of neonatal depression
    • Usually combined with a local anesthetic agent for spinal and epidural analgesia
    • Large doses (>150 mcg) may interfere with early breastfeeding
  • Morphine
    • Reserved for early labor pain relief due to its sedative effect and longer duration of action
    • Low-dose Morphine (≤0.25 mg) has been used with intrathecal Bupivacaine and Fentanyl for labor analgesia resulting in short latency and prolonged duration of analgesia
      • This combination is useful in situations where continuous epidural infusion is not possible and single-shot spinal techniques are used

Nerve Blocks

Paracervical Block

  • Bilateral injection of local anesthesia into the submucosa of the fornix of the vagina lateral to the cervix that is effective only during the 1st stage of labor
    • Should not be given in the 2nd stage of labor because of the position of fetal head
  • Effects:
    • Analgesic effect lasts for about 2 hours and may require repeated blocks
    • Provides pain relief without somatic sensory or motor block
    • Pain relief is not maintained and the pain due to distension of the pelvic floor, vagina, or perineum is not relieved
    • Use is limited by its association with fetal bradycardia which can progress and lead to severe adverse outcomes (eg perinatal death)
  • Does not require an anesthesiologist for administration
  • Should not be used in situations of potential fetal compromise (eg non-reassuring fetal heart tracings or uteroplacental insufficiency)

Paravertebral Lumbar Sympathetic Block

  • Interferes with transmission of visceral afferent nerve impulses from the uterus and cervix
  • Effects:
    • Provides analgesia for the 1st stage of labor without any motor block
    • Labor progress is accelerated than with epidural analgesia
  • May be useful in patients with previous back surgery
  • Less associated with fetal bradycardia compared to paracervical block
  • Not a continuous analgesia and is more difficult to administer

Pudendal Block

  • Anesthetic agent is administered just before delivery and commonly performed by the obstetrician
    • Given in late 1st stage of labor through perineal repair to relieve pain radiated to sacral nerves
  • Local anesthesia is injected passing through the sacrospinous ligament to infiltrate the pudendal nerve and repeated on the other side
    • Aspirate before injecting as large vessels may be near injection site
  • Pudendal block is not usually sufficient for cases when complete visualization of the cervix and upper vagina are necessary or when manual exploration of the uterine cavity is needed
  • Effects:
    • Provides vaginal, vulvar and perineal anesthesia adequate for spontaneous vaginal and low- or outlet-forceps delivery
    • Earlier pudendal nerve block done just before or after complete cervical dilation gives better analgesia, does not increase the incidence of instrumental delivery, and allows for a repeated block if the initial block fails
  • Maternal and fetal complications are rare

Perineal Infiltration

  • Perineal infiltration of local anesthetic agent is done before episiotomy and delivery or after delivery into the site of lacerations to be repaired or around the episiotomy wound if there is inadequate analgesia
    • Avoid routine episiotomy in spontaneous vaginal deliveries
  • Does not provide motor relaxation
  • May be complicated by direct injection of local anesthesia into the fetal scalp which may result to neonatal local anesthetic toxicity

Non-Pharmacological Therapy

  • Alternative interventions that appear to be safe and effective and may be used during the 1st stage of labor and/or in settings with insufficient resources

Acupressure

  • Pressure is applied simultaneously to both sides of the lumbar spine during contractions
  • Promotes circulation of blood and secretion of neurotransmitters, thus maintaining the normal functions of the body and enhancing well-being
  • Studies have shown decreased 1st stage labor pain and shorter labor time

Acupuncture

  • Stimulates electrical properties that alter chemical neurotransmitters and release endorphins
  • Studies have shown that it caused lower use of epidural and systemic opioid analgesia and augmentation
  • Associated with lesser assisted vaginal deliveries and cesarean sections
  • Time consuming due to the need of long induction period to achieve a good analgesic effect

Application of Cold and Heat

  • Application of cold and heat to painful areas of the body decreases pain perception and muscle spasms
  • Cold compress numbs an area slowing the transmission of pain that lasts longer than heat
  • Warm compress increases pain threshold and circulation and relaxes muscles
  • Temperature should be monitored in order to avoid injury to the woman’s skin

Continuous Labor Support

  • Refers to the non-medical support of the parturient by a trained person (eg doula) who provides physical comfort, emotional support, guidance during parturition, and eases the communication between patient and hospital staff
  • Useful in all stages of labor, has been shown to have shorter labors, lower operative vaginal and cesarean deliveries (increased potential for spontaneous vaginal deliveries), less need for pain medications, and greater satisfaction
    • Fewer women had unsatisfactory birth experiences
    • May have greater benefit in women not accompanied by a loved one and women with a labor support provider who is not a member of the hospital staff
    • Neonatal outcome is not altered

Environmental Control

  • Adjusting room temperature and lighting and decreasing distracting noises create a comforting atmosphere to the parturient
  • Music activates the right side of the brain and can help mediate pain because of its calming effect
    • Choice of music depends on what the patient finds relaxing and comforting
    • A study showed that soft instrumental music during the active phase of labor decreased anxiety and sensation of pain
    • Music with steady beat may stimulate and promote movement in the latter stages of labor

Hydrotherapy

Warm Water Baths

  • Immersion in warm water deep enough to cover the woman’s abdomen during active labor (not birth)
  • Studies show that women experience less pain and analgesic use without change in the duration of labor, rate of operative delivery, or neonatal outcome
    • It also enhanced relaxation, increased satisfaction and self-esteem, and improved childbirth experience
  • Fetal monitoring is not possible with parturient’s abdomen submerged, making this an unacceptable therapy for complicated pregnancy
  • Temperature of the woman and water should be checked every hour
    • Temperature of the water should not be >37.5°C

Warm Shower

  • Skin stimulation of a warm shower reduces awareness of the pain

Hypnosis

  • A state of focused concentration wherein patient is relatively unaware of her surroundings
    • Lacks sufficient evidence on its effectivity over placebo for labor pain management
  • Can be considered as a helpful adjunct during labor and delivery
    • May reduce fear, tension and pain during labor and increase pain threshold
    • Parturients have greater control over painful contractions
    • Studies show that the use of pharmacologic analgesia was decreased
    • Data on progress of labor and neonatal outcome are inconclusive or limited

Massage Therapy

  • Form of touch which relaxes muscles, increases blood flow, and enhances release of endorphins thereby providing comfort while decreasing pain

Movement and Positions

  • Moving and proper positioning during labor reduces pain, analgesic use, perineal trauma and improves progress of labor by enabling more effective uterine contractions
  • Patient is directed to move in specific ways beginning at specific points for a specific length of time
  • Upright positions during 1st stage of labor and squatting during 2nd stage may speed up labor and increase comfort levels
    • Walking, rocking, or swaying may be helpful during contractions; kneeling over a birth ball or a pile of pillows, standing and leaning forward, and sitting backwards on a chair may provide comfort
  • The optimal position is determined by the woman’s assessment and desires, phase of labor, and fetal position

Psychoprophylaxis

  • Educates women about the anatomy and physiology of childbirth and instructs them on how to perform physical and mental relaxation
    • Diminishes labor pain by familiarizing with the childbirth process, creating an atmosphere of confidence, and having greater maternal satisfaction with a sense of achievement and happiness

Lamaze’s Method

  • Women focus on breathing patterns or concentration points (eg mark on a nearby wall) which should be able to block pain messages to the brain

Bradley’s Method

  • Parents work as a team and are taught about deep abdominal breathing and an understanding of the labor and delivery process

Sterile Water Injection

  • Intradermal injection of sterile water in the sacral area that causes much more painful sensation
  • Thought to relieve back pain during labor by counterirritation, inhibition of pain transmission by nerves, or by stimulation of endorphin production
  • May be an alternative in women who have lower back pain and like to avoid epidural analgesia
    • Shown not to overall decrease the need for other pain relievers
  • May only be used for severe back pain and not for labor pain experienced in the abdominal area
  • Advantages:
    • Provides rapid and effective low back pain relief during labor (within 2 minutes and lasts for up to 2 hours)
    • No known maternal or fetal side effects
    • Simple to use and with high level of success
    • Decreases need and delays the use of epidural anesthesia
    • May reduce the rate of cesarean deliveries
    • May be used in the 1st and 2nd stage of labor and while waiting for an anesthesiologist
    • May be used in rural/remote areas and developing countries where alternative therapy is not available
    • Has an analgesic effect on pelvic floor tone, cervical tension and fetal rotation
  • Maternal satisfaction varies

Transcutaneous Electrical Nerve Stimulation (TENS)

  • Low-intensity, high-frequency electrical impulses applied to the lower back directed to the posterior roots of the nerves innervating the uterus
  • Electrical current sensation may decrease the mother’s awareness of contraction pain
  • Studies are inconsistent, but generally show that labor pain or use of other analgesic modalities is not decreased
    • Often delays the need for pharmacological analgesia; however, benefit is limited
    • May be beneficial for labor pain localized in the back
  • Not to be offered to women in established labor 

Touch Therapy

  • Application of pressure with hands to the back, abdomen, hips, thighs, sacrum, or perineum during painful uterine contractions
  • Conveys caring, reassurance and understanding to patients
    • Encourages comfort and reduces anxiety
    • Studies have shown that parturients have lesser pain and need for pain relief
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