Dr RAHUL VARSHNEY

As noted by the ASA and the ACOG,

“There is no other circumstance where it is considered acceptable for a person to experience severe pain,

amenable to safe intervention, while under a physician’s care.”

Philosophy Of Labour Analgesia

• Unfortunately, labor represents one of the few circumstances in which theprovision of effective analgesia is alleged to interfere with the parturient’s andobstetrician’s goal (e.g., spontaneous vaginal delivery).

• given the complicated neurohumoral and mechanical processes involved inchildbirth, it would be unreasonable to expect that neuroblockade of the lower halfof the body would not have an effect on this process, whether positive or negative.

• Anesthesia providers should identify those methods of analgesia that provide themost effective pain relief without unduly increasing the risk for obstetricintervention.

• Despite these risks, many women opt for neuraxial analgesia because no othermethod of labor analgesia provides its benefits (almost complete analgesia), andthe risks are acceptably low.

The Physiology of Pain in Labor

1st stage of labor – mostly visceral

◦ Dilation of the cervix and distention ofthe lower uterine segment

◦ Dull, aching and poorly localized

◦ Slow conducting, visceral C fibers, enterspinal cord at T10 to L1

2nd stage of labor – mostly somatic

◦ Distention of the pelvic floor, vaginaand perineum

◦ Sharp, severe and well localized

◦ Rapidly conducting A-delta fibers, enterspinal cord at S2 to S4

• Pain during first stage is visceral and is therefore mediated by the T10 throughL1 segments of the spine, whereas during the later part of the first stage andthroughout the second stage and additional somatic component is presentmediated by the S1 through S4 segments of he spine.

• The first to use Ether and Chloroformfor pain relief in labour in the UnitedKingdom was the eminent ScottishObstetrician Sir James YoungSimpson, Professor of Midwifery atthe University of Edinburgh. OnJanuary 19, 1847 he administeredether to an obstetric patient and thusbegan a new era in the effectivemanagement of pain in childbirth.

HISTORY!!!

• The first woman anesthetized for childbirth in the United States was FannyLongfellow in 1847 for her third child. She was the wife of the American poetHenry Wadsworth Longfellow who actually administered the ether.

• The second woman who was to become famous was Emma Darwin, the wife ofCharles Darwin the eminent 19th century Naturalist. Emma had chloroform givento her by her husband for the last 2 of her 8 births. The first time she usedchloroform was in 1847 which was before Queen Victoria (1853) and no doubt itleft an indelible impression upon her so much so that for her last birth she wasscreaming ‘Get me the chloroform”.

• The third, who was not only the most famous of them all, but the most influential,was Queen Victoria who in 1853, undaunted by the clergy and with the strongencouragement of her husband Prince Albert, convinced her reluctant physicians,to have chloroform administered to her by Dr. John Snow for her 8th confinement ofPrince Leopold.

Regional anesthetic techniques, wereintroduced to obstetrics in 1900,when Oskar Kreis described the useof spinal anesthesia.

Does Labor Pain Need Analgesia?

Analgesia for Labor and Delivery

• Always controversial!

• “Birth is a natural process”

• Women should suffer!!

• Concerns for mother’s safety

• Concerns for baby

• Concerns for effects on labor

• In a survey of 1000 consecutive women who chose a variety of analgesic techniques

for labor and vaginal delivery (including non-pharmacologic methods,

transcutaneous electrical nerve stimulation, intramuscular meperidine, inhalation

of nitrous oxide, epidural analgesia, and a combination of these techniques), pain

relief and overall satisfaction with the birth experience were greater in patients who

received epidural analgesia.

Other Benefits

• Effective epidural analgesia reduces maternal

plasma concentrations of catecholamines.

• Decreased alpha- and beta-adrenergic receptor

stimulation may result in better utero-placental

perfusion and more effective uterine activity.

• Effective epidural analgesia blunts this

“Hyperventilation- Hypoventilation” cycle

The ideal labour analgesic technique

• is safe for both the mother and the infant,

• does not interfere with the progress of labor and delivery,

• provides flexibility in response to changing conditions,

• provides consistent pain relief,

• has a long duration of action,

• minimizes undesirable side effects (e.g., motor block), and

• minimizes ongoing demands on the anesthesia provider’s time.

Indications

• In 2008 and 2010, respectively, the ACOG and the

ASA reaffirmed an earlier, jointly published opinion

that stated that “in the absence of a medical contraindication,

maternal request is a sufficient medical indication for pain relief during labor.”

• Epidural analgesia may facilitate an atraumatic vaginal breech delivery, the vaginal deliveryof twin infants, and vaginal delivery of a preterm infant.

• Facilitates blood pressure control in pre-eclamptic women.

• Blunts the hemodynamic effects of uterine contractions (e.g., sudden increase in cardiacpreload) and the associated pain response (tachycardia, increased systemic vascularresistance, hypertension, hyperventilation) in patients with other medical complications(e.g., mitral stenosis, spinal cord injury, intracranial neurovascular disease)

Contraindication

• Patient refusal or inability to cooperate

• Increased intracranial pressure secondary to a mass lesion

• Skin or soft tissue infection at the site of needle placement

• Frank coagulopathy

• Recent pharmacologic anticoagulation*

• Uncorrected maternal hypovolemia (e.g., hemorrhage)

• Inadequate training in or experience with the technique

• Inadequate resources (e.g., staff, equipment) for monitoring and resuscitation

Types of Labor Analgesia

1. Non-pharmacological analgesia

2. Pharmacological

3. Regional Anesthesia/Analgesia

Regional Anesthesia/Analgesia

• Epidural analgesia

• Spinal analgesia

• Combined Spinal Epidural (CSE) analgesia

• Continuous Epidural analgesia

• Continuous spinal analgesia

• Paracervical block

• Lumbar sympathetic block

• Pudendal block

• Perineal infiltration

Epidural Analgesia

Patient Positioning

• Sitting or lateral??

• There is little evidence that patient

position influences the extent of

neuroblockade during initiation of

epidural analgesia/anaesthesia.

Intravenous Hydration

• ASA Task Force on Obstetric Anesthesia has stated that a fixed volume ofintravenous fluid is not required before neuraxial analgesia is initiated. Severehypotension is less likely with the contemporary practice of administering adilute solution of local anesthetic for epidural analgesia or an intrathecalopioid for spinal analgesia.

• Studies of intravenous hydration and spinal anesthesia for cesarean deliverysuggest that there is no advantage to administering the fluid before theinitiation of anesthesia (preload) compared with administering the fluid at thetime of initiation of anesthesia (co-load).

• A balanced electrolyte solution (e.g., lactated Ringer’s solution) withoutdextrose is the most commonly used intravenous fluid for bolusadministration.

Choice of Drugs

• Local anesthetics were administered to block both the visceral and the somaticpain of labor.

• Intrathecal opioids effectively relieve the visceral pain of the early first stage oflabor, although they must be combined with a local anesthetic to effectively relievethe somatic pain of the late first stage and the second stage of labor.

• The addition of an opioid to the local anesthetic also shortens latency.

• Contemporary epidural labor analgesia practice most often incorporates low dosesof a long-acting local anesthetic combined with a lipid-soluble opioid.

• Pain and analgesic requirements vary depending on several factors, includingparity, stage of labor, presence of ruptured membranes, oxytocin augmentation, andwhether the opioid is administered in combination with a local anesthetic.

Local Anaesthetics

Bupivacaine

• most commonly used agent for epidural labor analgesia.

• Highly protein bound, limits trans-placental transfer.

• After epidural administration of bupivacaine (without opioid) during labor, the patientfirst perceives pain relief within 8 to 10 minutes, but approximately 20 minutes isrequired to achieve the peak effect. Duration of analgesia is approximately 90 minutes.

Ropivacaine

Levo bupivacaine

Lidocaine

2-chlorprocaine

Opioids

Lipid-Soluble Opioids: Fentanyl and Sufentanil.

• In clinical practice, epidural fentanyl and sufentanil are usually administered with a localanesthetic for the initiation of analgesia.

• The addition of a lipid-soluble opioid to a local anesthetic for neuraxial labor analgesiadecreases latency, prolongs the duration of analgesia, decreases epidural LArequirement , decreases motor blockade and improves the quality of analgesia.

• Advantages of a lower total dose of local anesthetic include

1. decreased risk for local anesthetic systemic toxicity,

2. decreased risk for high or total spinal anesthesia,

3. decreased plasma concentrations of local anesthetic in the fetus and neonate, and

4. decreased intensity of motor blockade.

Alfentanil

Morphine

Meperidine

Butorphanol

Diamorphine

Adjuvants

• Epinephrine

• Clonidine

• Neostigmine

Epidural Test Dose

• Purpose is to help identify unintentional cannulation of a vein or the

subarachnoid space.

• Epidural test dose: Placement of an epidural catheter and administration

of a standard lidocaine 45 mg/epinephrine 15 μg.

• Combination of a low-dose, long-acting amide local anaesthetic and alipid soluble opioid

• This approach improves safety andleads to less motor blockade andgreater patient satisfaction.

MAINTENANCE OF ANALGESIA

Administration Techniques

1. Intermittent Bolus

• Analgesia re-established with bolus injection of 8 to 12 ml of LA/Opioid solution.

• Pain relief is constantly interrupted by regression of analgesia.

• The spread and quality of analgesia may change with repeated lumbar epidural injections.

2. Continuous infusion

• Prolonged infusion might lead to Significant motor blockade. Therefore dose requires titration.

• Strict monitoring is required as migration of catheter into subarachnoid, subdural or intravenous space are likely to go unnoticed.

3. Patient controlled Epidural Analgesia

• Bupivacaine consumption is higher in PCEA with a background infusion than in a purePCEA technique without a background infusion.

• A meta-analysis of five studies reported in the ASA Practice Guidelines for ObstetricAnesthesia concluded that a background infusion provides better analgesia than purePCEA without a background infusion.

• There is no evidence that the higher local anesthetic dose associated with a backgroundinfusion increases motor blockade or has adverse effects on obstetric outcome when low-concentration infusion solutions are used.

4. Timed Intermittent bolus Injection

Ambulatory Neuraxial Analgesia

• Applied to any neuraxial analgesictechnique that allows safeambulation. It was first coined todescribe low-dose CSE opioidanalgesia because motor functionwas maintained and the ability towalk was not impaired.

Side Effects of Neuraxial Analgesia

1. Hypotension

2. Pruritis

3. Nausea and vomiting

4. Fever

5. Shivering

6. Urinary retension

7. Recrudescence of HSV

8. Delayed Gastric emptying

1. Hypotension

• The incidence of hypotension after initiation of neuraxial analgesia during laboris ≈14%.

• In women undergoing spinal anesthesia for cesarean delivery there is nodifference in the incidence of hypotension when crystalloid is administered as arapid bolus prior to the initiation of neuroblockade (preload) compared withadministration concurrently with the initiation of anesthesia (co-load). †

• The hypotension associated with neuraxial analgesia is usually easily treated.Treatment includes the administration of additional intravenous crystalloid,placement of the mother in the full lateral and Trendelenburg position, andadministration of an intravenous vasopressor

†Preload or coload for spinal anesthesia for elective Cesarean delivery: a metaanalysis. Can J Anaesth 2010; 57:24-31.

2. Pruritus

• Most common side effect of epidural orintrathecal opioid administration.

• The incidence and severity of pruritus aredose dependent for both epidural andspinal opioid administration. The co-administration of local anaestheticdecreases the incidence of pruritus,whereas the co-administration ofepinephrine may worsen pruritus.

• The most effective treatment is a centrallyacting μ-opioid antagonist (e.g., naloxoneor naltrexone) or a partial agonist-antagonist such as nalbuphine.

3. Nausea and Vomiting

• Nausea is less common after epidural or intrathecal opioidadministration during labor than after the administration of thesame drugs for post– caesarean delivery analgesia. Norris et al.noted that women who received epidural or intrathecal opioidanalgesia during labor had an incidence of nausea of only 1.0%or 2.4%, respectively.

• Metoclopramide, ondansetron and droperidol have been usedprophylactically in women undergoing neuraxial opioidanalgesia.

Complications of Neuraxial analgesia

1. Inadequate analgesia

2. Unintentional dural puncture

3. Respiratory Depression

4. Intravascular injection of LA

5. High and Total spinal anesthesia

6. Extensive Motor Blockade

7. Prolonged Blockade

8. Sensory changes

9. Back Pain

10. Pelvic floor injury

1. Inadequate Analgesia

• Successful location of the epidural space is not always possible, and satisfactoryanalgesia does not always occur, even when the epidural space has beenidentified correctly. Factors such as patient age and weight, the specifictechnique, the type of epidural catheter, and the skill of the anesthesia providerare associated with the rate of failure of neuraxial analgesia.

• The risk for failed anesthesia and the potential need to place a second epiduralcatheter should be discussed with the patient during the preanestheticevaluation, before placement of the first epidural catheter.

• Three types mainly:

1. Extent of block inadequate.

2. Asymmetric block

3. Breakthrough pain

2. Unintentional Dural Puncture

• Rate of unintentional Dural puncture with an epidural needle or catheter was 1.5%.

• Options:

1. Remove the needle and place an epidural catheter at another interspace;

2. If CSE analgesia was planned, the intrathecal dose may be injected through theepidural needle before it is removed and re-sited at a different interspace.

3. The Anaesthesia provider may place a catheter in the subarachnoid space andadminister continuous spinal analgesia for labor and delivery.

5. High and Total spinal Anaesthesia

• May occur after the unintentional and unrecognized injection of local anesthetic (via a needle or catheter) into either the subarachnoid or subdural space.

• Alternatively, the epidural catheter may migrate into the subarachnoid or subdural space during the course of labor and delivery.

• High spinal blockade may result from an overdose of local anesthetic in the epidural space.

• Extensive neuroblockade may also result from injection of a local anesthetic intosubdural space.

• Subdural injection may be difficult to diagnose because onset is later than that withan intrathecal injection and more closely resembles that associated with epiduralneuroblockade.

Impact on Duration of Labour

• A 2011 meta-analysis of 11 studies found no difference in the duration of the firststage of labor between women who were randomly assigned to receive epiduralanalgesia and those assigned to receive systemic opioid analgesia.

• Analgesia-related prolongation of the first stage of labor, if it occurs, is short, hasnot been shown to have adverse maternal or neonatal effects, and is probably ofminimal clinical significance.

First Stage of labour

Second Stage of labour• Meta-analyses of RCTs that compared neuraxial with systemic opioid analgesia

support the clinical observation that effective neuraxial analgesia prolongs thesecond stage of labor.

• The mean duration of the second stage was 15 to 20 minutes longer in womenrandomly assigned to receive neuraxial analgesia than in women assigned to receivesystemic opioid analgesia.

• It was concluded that the second stage of labor does not need to be terminated based on duration alone.

• Studies have confirmed that a delay in delivery is not harmful to the infant or mother provided that

(1) electronic FHR monitoring confirms the absence of non-reassuring fetal status,

(2) the mother is well hydrated and has adequate analgesia, and

(3) there is ongoing progress in the descent of the fetal head.

• The ACOG has stated that if progress is being made, the duration of the second

stage alone does not mandate intervention

Third stage

• Epidural analgesia was not associated with a prolonged third stage of labor. The duration of the third stage of labor was shorter in women who received epidural analgesia and subsequently required manual removal of the placenta.

• The ACOG supports the use of oxytocin for the treatment of dystocia or arrest of labor in the first or second stage, whether or not the patient is receiving neuraxial analgesia

• There was no difference in the mode of delivery or duration of labor with or without ambulation in neuraxial analgesia.

Among other factors . . .

Impact on Caesarean Delivery Rate

• The latest meta-analysis coveredoutcomes for 8417 womenrandomized to receive neuraxialor no neuraxial/no analgesia(control) from 27 trials The riskratio for caesarean delivery inwomen randomly assigned toreceive neuraxial analgesiacompared with those assignedto the control group was 1.10.

• Almost all studies found nodifference in the rate ofcaesarean delivery betweenwomen randomly assigned toreceive either neuraxial orsystemic opioid analgesia

Instrumental Vaginal Delivery Rate

• Most systematic reviews have concluded that epidural analgesia is associated with ahigher risk for instrumental vaginal delivery than systemic analgesia.

• In a meta-analysis of studies that compared CSE and epidural analgesia, theinstrumental vaginal delivery rate was lower in the CSE group than in the traditional“high-dose” epidural analgesia groups (risk ratio 0.80; 95% CI, 0.65 to 0.98), but therewas no difference between “low-dose” epidural and CSE analgesia.

• In a 2011 meta-analysis of 23 studies (n =7935), the risk ratio for instrumentalvaginal delivery in women randomlyassigned to receive epidural analgesia ornon-epidural/no analgesia was 1.42.

Timing of initiation of neuraxial analgesia

• In a retrospective study of 1917 nulliparous women, the rate of caesarean delivery was twice as high in women who received neuraxial analgesia at a cervical dilation less than 4 cm than in those in whom neuraxial analgesia was initiated at a cervical dilation of 4 cm or more.

• For many years the ACOG suggested that women delay requesting epidural analgesia “when feasible, until the cervix is dilated to 4 to 5 cm.”

Timing of initiation of neuraxial analgesia

• Later in 2006, subsequent to publication of various studies the ACOG published anupdate which has the following statement :

“Neuraxial analgesia techniques are the most effective and least depressant treatmentsfor labor pain. The American College of Obstetricians and Gynecologists previouslyrecommended that practitioners delay initiating epidural analgesia in nulliparouswomen until the cervical dilation reached 4-5 cm. However, more recent studies haveshown that epidural analgesia does not increase the risks of caesarean delivery. Thechoice of analgesic technique, agent, and dosage is based on many factors, includingpatient preference, medical status, and contraindications. The fear of unnecessarycaesarean delivery should not influence the method of pain relief that women canchoose during labor.”

Conclusion “The delivery of the infant into the arms of a conscious

and pain-free mother is one of the most exciting and rewarding moments in medicine.”

Moir DD. Extradural analgesia for caesarean section. Br J Anaesth 1979; 51: 1093.

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