Obstetrical Analgesia

Co-ordinator:- Dr. Roopesh Kumar (M.D) Speaker:- Dr. Sushil kr. patel

Introduction • Pregnancy and motherhood is a major milestone in the life of a female which change her

position in the family and the society giving more self confidence and independence. • Child birth is a painful process and pain relief during labour has always been associated

with myths and controversies. Several groups of people think that God has made this process painful and no interference should be done in it However, from the early days several methods including primitive use of rings, neck less, distraction, and counter stimulation have been used to relieve labour pain.

• In modern era various non- pharmacological and pharmacological methods are being practiced for labour analgesia.

• Use of labour analgesia has gained wide spread popularity ever since the three famous women, Fanny Longfellow wife of famous American poet Henry Wadsworth Longfellow (1847), Emma Darwin wife of Charles Darwin the eminent Naturalist, and Queen Victoria wife of Prince Albert (1853) not only accepted but strongly endorsed the use of analgesia during birth process .

• For labour analgesia, epidural administration of local anaesthetic agents and systemic (intravenous or intra- muscular) administration of opioids (narcotics) are the two most frequently employed pharmacologic methods in the United States.

• In developing countries like India national average acceptance of epidural analgesia for labour pain relief is almost negligible though sporadically few centre have a comprehensive labour analgesia program .

conti.....

• Throughout the history several measures have been used to relieve the labour pain.• In the earlier days extract of poppy, mandragora, alcohol were used to facilitate the

delivery without much pain. During last four decades labour analgesia has undergone extensive research and development to find out a technique which is safe for both mother and fetus .

History of development of different techniques used in labour analgesia• 1847 Ether • 1853 Chloroform • 1881 Nitrous Oxide • 1900 Spinal with Cocaine • 1902 Morphine and Hyoscine • 1909 Caudal Epidural • 1930 Sacral Epidural • 1940 Pethidine • 1943 Continuous Caudal Epidural • 1949 Continuous Lumber Epidural • 1958 Psycho prophylaxis by Lamaze • 1980 TENS

Ideal technique of labour analgesia

• Any drug or technique used in labour analgesia should be simple, safe and must have high technical success rate. It should be acceptable to mother and allow her active participation in the labour process.

• These drugs and or techniques should provide complete analgesia throughout the painful period of labour and must be devoid of any harmful effect on mother and labour process.

• These should maintain a complete fetal homeostasis without any depressant effect on fetus.

Physiology of Labor Pain

• During the first stage of labor, pain impulses arise primarily from the uterus. Uterine contractions may result in myometrial ischemia, which ultimately causes the release of bradykinin, histamine, and serotonin. In addition, stretching and distention of the lower uterine segment and cervix may stimulate mechanoreceptors.

• These noxious impulses follow the sensory nerve fibers that accompany sympathetic nerve endings; they travel through the paracervical region and the hypogastric plexus to enter the lumbar sympathetic chain.

• These stimuli enter the spinal cord at the T10, T11, T12, and L1 spinal segments. Parturients describe this pain as dull in nature(visceral) and often poorly localized.

• With onset of the second stage of labor and stretching of the perineum, somatic afferent nerve fibers transmit impulses through the pudendal nerve to the spinal cord at the S2, S3, and S4 levels .

Figure 3: Pain pathways in a parturient.

Figure 4: Dermatomal level of the lower abdomen, perineal area, hip, and thighs.

Timing for analgesia

• Timing for labour analgesia always has been a point of debate among obstetrician and anaesthesiologist.

• At present time there are no sufficient data available to determine the exact timing or indication like degree of cervical dilatation or fetal head descent to which analgesia should be started.

• American college of Obstetrician and Gynecologists recommends that when �feasible obstetric practitioner should delay the administration of epidural analgesia in nulliparous women until the cervical dilatation reaches at least 4-5 cm and other analgesics should be used until that time . �

• Wang et al in a study in 12793 parturients found no difference in duration of labour or incidence of caesarean deliveries with epidural analgesia given either in the early (cervical dilatation of 1-4 cm) or late (> 4 cm) stage of labour.

Techniques of labour analgesia

Non-pharmacological

1. Psychoprophylaxis Breathing exercise Duola 2. Hypnosis 3. TENS 4. Acupuncture and Acupressure 5. Hydro therapy 6. Miscellaneous Yoga Music therapy

Pharmacological 1. Inhalation analgesia N2O:O2 , Ether, trilene Halogenated compounds like Enflurane, isoflurane, sevoflurane2.Parenteral analgesia Opioids: pethidine, pentazocine, fentanyl Remifentanil, sufentanil , , meperidine , butorphanol

and nalbuphine. Non-opioid: tramadol Sedative & tranquiliser: diazepam, midazolam Ketamine 3. Regional analgesia Lumbar epidural Caudal epidural Spinal analgesia Combined spinal-epidural Walking epidural 4. Pudendal nerve block 5. Paracervical block

Psycho prophylaxis; • These methods do not change the intensity of the pain but they do alter the perception of

pain and they reduce maternal suffering. • Psycho prophylaxis helps women interpret the pain as a normal part of labour so they do

not feel threaten from it and find it easier to cope with it. • Different methods have different approaches but one of the great advantages of all is that

they include extensive education regarding the normal labour process. By providing quality education they prepare the mother to deal with it better and reduce the anxiety of the unknown.

• This avoids the huge emotional stress and negative feelings of failure that some women are left with when they decide to use medications for pain relief.

Lamaze method- The Lamaze method teaches women to respond positively to the pain of labor. Mothers are taught to relax during the contraction with the help of a birth partner, contributing to the process of labor without the use of drugs.

Transcutaneous electrical nerve stimulation (TENS)-• Electrodes are placed about 2cm over the T10-L1 dermatomes either side of the spinous

processes to provide analgesia for the first stage of labour. • A second set of electrodes is placed over the S2 – S4 dermatomes for second stage pain

relief. Women can alter the amount of current supplied to the electrodes providing some degree of control throughout their labour

•

TENS.....

• Blockade of pain transmission to the brain through stimulation of A-fibre transmission and local release of β-endorphins are suggested theories for TENS analgesia; however there is no evidence that TENS provides more analgesia than placebo.

• Despite this, TENS has minimal side effects and may be appropriate for women who have contraindications to other methods of pain relief or

where other methods are not available.

Pharmacological 1. Inhalation analgesia • Inhaled analgesia can be defined as the administration of subanesthetic

concentrations of inhaled anesthetics to relieve pain during labor.• This pain relief technique should not be confused with inhaled anesthesia that

produces unconsciousness and loss of protective laryngeal reflexes. • Although inhaled analgesia provides a limited amount of pain relief, it is not

adequate to provide sufficient pain relief for most mothers. It may, however, have a place as an adjunct to neuraxial techniques or in parturients in whom regional anesthesia is not possible.

• Inhaled analgesics can be administered either intermittently (during contractions) or continuously. They can be self-administered, but the patient should have a health care provider present to ensure an adequate level of consciousness and proper use of the equipment.

• Although inhaled analgesics continue to be used in parts of Europe as well as developing countries, they are seldom used for labor analgesia in the United States and scavenging of gases remains a concern.

Conti.....• N 2 O:O2 Inhalation 50:50• Trilene Inhalation 0.3%-0.5% • Enflurane Inhalation 0.3%-1.0%• Isoflurane Inhalation 0.2%-0.7% • Sevoflurane Inhalation 0.8%-1.0% Entonox (50 : 50 N2O/O2 mixture) has been used for many years as both a sole analgesic

and an adjuvant to systemic and regional techniques for labor. Associated side effects include dizziness, nausea, dysphoria, and lack of cooperation.

The maximum analgesic effect occurs after 45 to 60 seconds, and it is therefore important that the parturient use Entonox at the early onset of her contractions and discontinue its use after the peak of the contraction.

The lack of scavenging systems in labor rooms may theoretically put staff at risk of exposure to excessive levels over a prolonged period.

The administration of nitrous oxide and oxygen in a 50 : 50 combination appears to have no effect on hepatic, renal, cardiac, or pulmonary functions. A recent meta-analysis by Kronberg and Thompson concludes that inhaled nitrous oxide relieves labor pain to a significant degree in most patients but does not provide complete analgesia for many.

The analgesic effect of nitrous oxide does also seem to be dose dependent, which supports its analgesic efficacy during labor.

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• Desflurane , enflurane, and isoflurane have also been used to provide labor analgesia, but their effectiveness is comparable to that of nitrous oxide.

• More recent studies suggest sevoflurane as an effective labor analgesic. An inspired concentration of 0.8% appears to be acceptable and effective for labor analgesia.

• Sevoflurane, when compared with Entonox, provided superior pain relief but with more intense sedation, without adverse effects and which was acceptable to mothers.

• use of these volatile analgesics, however, is limited by drowsiness, unpleasant smell, and high cost. The major risk when using volatile analgesics is accidental overdose resulting in unconsciousness and loss of protective airway reflexes.

2.Parenteral analgesia

Opioids are the most commonly used class of drugs for systemic medication in laboring women .

• All opioids have various degrees of side effects, including respiratory depression, nausea, and vomiting, as well as mental status changes ranging from euphoria to excessive sedation.

• All opioids cross to the placental circulation freely because of their physicochemical characteristics, and they may cause respiratory depression in the newborn. However, when used appropriately, systemic opioids can partially alleviate labor pain for short periods.

• Other systemic drugs used in the treatment of labor pain include sedative-tranquilizers and ketamine.

Meperidine-• In the past, meperidine was the most commonly used systemic analgesic to

ameliorate pain during the first stage of labor.• It can be administered by IV injection (effective analgesia in 5–10 minutes) or

intramuscularly (peak effect in 40–50 minutes). It was also commonly used for postoperative pain in the general population

Opioid.......• But with the popularity of its administration, disturbing side effects began to

emerge.• One of the most serious side effects was the occurrence of seizures both from the

primary drug effect and from its metabolite, normeperidine. .• In the pregnant patient at risk for seizures—that is, with pregnancy-induced

hypertension or preeclampsia—confusing the picture by the administration of a drug known to cause seizures complicates patient care.

• Other side effects are nausea and vomiting, dose related depression of ventilation, orthostatic hypotension, the potential for neonatal depression, and euphoria out of proportion to the analgesic effect, leading to misuse of the drug.

• Meperidine may also cause transient alterations of the fetal heart rate, such as decreased beat-to-beat variability and tachycardia. Among other factors, the risk of neonatal depression is related to the interval from the last drug injection to delivery.

• The placental transfer of an active metabolite, normeperidine, which has a long elimination half-life in the neonate (62 hours), has also been implicated in contributing to neonatal depression and subtle neonatal neurobehavioral dysfunction. Consequently, the use of meperidine has fallen out of favor as an analgesic for labor

Fentanyl• Fentanyl is an alternative analgesic option for patients in whom neuraxial anesthesia

is contraindicated.• Its short half-life makes it suitable for prolonged use in labor, either as an intravenous

bolus or as an analgesic administered by means of a patient-controlled analgesia delivery system.

• It provides reasonable levels of analgesia with minimal neonatal depression. Although it is a potent opioid, its use in labor has been limited by side effects and short duration of action.

• Fentanyl crosses the placenta; one study that evaluated intravenous fentanyl for labor reported that 4 of 11 fetuses whose mothers received fentanyl for analgesia during labor required naloxone treatment.

• The usual dose of fentanyl for labor analgesia is 25 to 50 µg intravenously. The peak effect occurs within 3 to 5 minutes and has a duration of 30 to 60 minutes.

• fentanyl in labor has suggested that mild maternal sedation is apparent after the administration of 50 or 100 µg. In addition, a transient decrease in FHR variability was also noted.

• Despite these limitations, several investigators have determined that intravenous fentanyl is preferable to meperidine as a labor analgesic. Fentanyl offers another advantage in that it can be administered in nonparenteral modalities, including subcutaneously, orally, and by patch.

Remifentanil

• Remifentanil is an opioid that is rapidly metabolized by serum and tissue cholinesterases, and consequently, has a short (3-minute), context-sensitive half-time.

• When used in bolus dosing (0.3–0.8 mcg/kg per bolus), remifentanil has been found to have an acceptable level of maternal side effects and minimal effect on the neonate.

• Remifentanil crosses the placenta and appears to be either rapidly metabolized or redistributed in the neonate.

• Apgar and neurobehavioral scores were good in neonates whose mothers were given an intravenous infusion of remifentanil, 0.1 mcgkg/ min during cesarean section delivery under epidural anesthesia.

• When administered by patient-controlled analgesia, remifentanil has been found to provide better pain relief, equivalent hemodynamic stability, less sedation, and a lesser degree of oxygen desaturation when compared with meperidine.

• In countries outside the United States, intermittent nitrous oxide has been used for labor analgesia. When comparing remifentanil with nitrous oxide, remifentanil was found to provide better pain relief with fewer side effects.

Opioid agonists–antagonists - butorphanol and nalbuphine• butorphanol and nalbuphine, have also been used for obstetric analgesia.• These drugs have the proposed benefits of a lower incidence of nause, vomiting,

and dysphoria, as well as a “ceiling effect” on depression of ventilation. • Butorphanol is probably the most popular; unlike meperidine, it is biotransformed

into inactive metabolites and has a ceiling effect on depression of ventilation in doses exceeding 2 mg.

• A potential disadvantage is a high incidence of maternal sedation. The recommended dose is 1–2 mg by IV or IM injection.

• Nalbuphine 10 mg IV or IM is an alternative to butorphanol.

Naloxone, a pure opioid antagonist, should not be administered to the mother shortly before delivery to prevent neonatal ventilatory depression because it reverses maternal analgesia at a time when it is most needed.

• In some instances, naloxone has been reported to cause maternal pulmonary edema and even cardiac arrest.

• If necessary, the drug should be given directly to the newborn IM (0.1 mg/kg).

Sedative-Tranquilizers• Sedative-tranquilizers, including barbiturates, phenothiazines, hydroxyzine, and

benzodiazepines, have been used for sedation, anxiolysis, or both during early labor and before cesarean delivery .

• Although barbiturates such as secobarbital were once popular, they are currently unfashionable because of antianalgesic effects in the mother and prolonged depressant effects in the neonate.

• Even with small doses of barbiturates that result in no depression of the Apgar score, the newborn's attention span may be depressed for more than 4 days.

Promethazine is the most commonly administered phenothiazine in obstetrics. Used with meperidine, it can be given in doses of 25 to 50 mg to prevent emesis. Its ability to potentiate the analgesic effects of opioids, however, is in doubt.

Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist that produces dissociative anesthesia and has been used in pregnant patients.

• As a phenylcyclidine derivative, its mechanism of action may be mediated by an interaction with phencyclidine receptors located in the limbic and corticothalamic areas of the brain. Some evidence, however, suggests that NMDA antagonism is central to the effects of ketamine.

Sedative-Tranquilizers conti.....

Ketamine- has been used in subanesthetic doses (0.5 to 1 mg/kg or 10 mg every 2 to 5 minutes to a total of 1 mg/kg in 30 minutes) during labor.

• In addition to its use in labor, ketamine in a dose of 25 to 50 µg can be used to supplement an incomplete neuraxial blockade for cesarean section. Its main disadvantages are the potential for hypertension and emergence reactions.

• High doses (>2 mg/kg) can produce psychomimetic effects and increased uterine tone, which may cause low Apgar scores and abnormalities in neonatal muscle tone.

Benzodiazepines -such as diazepam , lorazepam , and midazolam can be used as sedatives and anxiolytics in labor. However, these drugs readily cross the placenta, with elimination half-lives as long as 48 hours for diazepam and upward of 120 hours for its main metabolite N-desmethyldiazepam.

• The use of these drugs during labor will obviously have no effect on fetal malformations, but they may be associated with other problems in the neonate, including sedation, hypotonia, cyanosis, and impaired metabolic responses to stress.

DRUG ROUTE DOSE

Pethidine I'm./i.v. 0.25-0.5mg-kg i.v. 1.0-2.0 mg-kg i.m.

Pentazocine I'm./i.v. 0.5-1.0 mg-kg

Butorphanol i.m./i.v. 1.0-2.0 mg-kg

Fentany i.v./infusion/PCIA 1.0-2.0 µg-kg IV 50-100 µg-hr infusion 20 µg with 5 min lockout PCIA

Remifentanil

Sufentanil

PCIA Bolus/PCIA/PCEA Start with 0,1µg-kg 5.0-7.5 µg as bolus 0.25-0.5 µg-ml in PCEA

Non-opiod Tramadol

i.m./i.v 1.0-2.0 mg-kg

Sedative/tranquiliser DRUG ROUTE DOSE

Diazepam i.m./i.v. 5.0 -10 mg

Midazolam i.m./i.v. 1.0-2.0 mg

Miscellaneous

Ketamine i.v. 10-15 mg bolus every 3-5 min Up to 75-100 mg

Regional Analgesia• Regional techniques provide excellent analgesia with minimal depressant effects

in mother and fetus.• The techniques most commonly used for labor anesthesia include central

neuraxial blocks (spinal, epidural, and combined spinal/epidural), paracervical, and pudendal blocks, and, less frequently, lumbar sympathetic blocks.

• Hypotension resulting from sympathectomy is the most common complication that occurs with central neuraxial blockade. Therefore, maternal blood pressure must be monitored at regular intervals, typically a very 2–5 minutes for approximately 15–20 minutes after the initiation of the block and at routine intervals thereafter.

• Regional analgesia may be contraindicated in the presence of severe coagulopathy, acute hypovolemia, or infection at the site of needle insertion. Chorioamnionitis without sepsis, is not a contraindication to central neuraxial blockade

Patient Evaluation and Preparation

• It is important to assess all patients before placement of a regional block by obtaining a focused medical and obstetric history, performing a clinical examination, and evaluating the airway.

• The obstetric plan and fetal well-being should be noted during this preoperative assessment. Informed consent must be obtained, and the anesthesiologist should explain the procedure and the potential complications of the technique.

• A full check of emergency equipment should be performed to ensure the immediate availability of resuscitative drugs and equipment. An intravenous infusion should be started, and appropriate maternal and fetal monitoring should be in place before starting the procedure

Epidural Analgesia• Effective analgesia for the first stage of labor is achieved by blocking the T10-Ll

dermatomes with a low concentrations of local anesthetic, often in combination with a lipid-soluble opioid.

• For the second stage of labor and delivery, because of pain due to vaginal distention and perineal pressure, the block should be extended to include the pudendal segments, S2-4 .

• There has been concern that early initiation of epidural analgesia during the latent phase of labor (2–4 cm cervical dilation) may result in prolongation of the first stage of labor and a higher incidence of dystocia and cesarean section delivery, particularly in nulliparous women. Generally speaking, the first stage of labor is not prolonged by epidural analgesia, provided that aortocaval compression is avoided.

• Chestnut et demonstrated that the incidence of cesarean section delivery was no different in nulliparous women having epidural analgesia initiated during the latent phase (at 4 cm dilation) compared with women whose analgesia was initiated during the active phase.

• Others have shown that epidural analgesia is not associated with an increased incidence of cesarean section delivery compared with IV patient-controlled analgesia in nulliparous women.

• However, a prolongation of the second stage of labor has been reported in nulliparous women, possibly owing to a decrease in expulsive forces or malposition of the vertex.

Epidural Analgesia......

• Thus, with use of epidural analgesia, the American College of Obstetricians and Gynecologists (ACOG) has defined an abnormally prolonged second stage of labor as longer than 3 hours in nulliparous and 2 hours in multiparous women.

• A longer second stage of labor may be minimized by the use of an ultra-dilute local anesthetic solution in combination with opioid.

• Long-acting amides such as bupivacaine, ropivacaine, and levobupivacaine are most frequently used because they produce excellent sensory analgesia while sparing motor function, particularly at the low concentrations used for epidural analgesia.

• Analgesia for the first stage of labor may be achieved with 5–10 mL of bupivacaine, ropivacaine, or levobupivacaine (0.125–0.25%) followed by a continuous infusion (8–12 mL/h) of 0.0625% bupivacaine or levobupivacaine, or 0.1% ropivacaine. Fentanyl 1–2 mcg/mL or sufentanil 0.3–0.5 mcg/mL may be added.

• During the actual delivery, the perineum may be blocked with 10 mL of 0.5% bupivacaine, 1% lidocaine, or, if a rapid effect is required, 2% chloroprocaine in the semirecumbent position.

Epidural Analgesia.......

• There is controversy regarding the need for a test dose when using a dilute solution of local anesthetic.

• Catheter aspiration alone is not always diagnostic. For that reason, some authors believe that a test dose should be administered to improve detection of an intrathecally or intravascularly placed epidural catheter.

• If injected into a blood vessel, 15 mcg epinephrine results in a change in heart rate of 20–30 bpm with a slight increase in blood pressure within 30 seconds of administration. The duration is approximately 30 seconds. The anesthesiologist should observe the tachometer during the first minute after injection to determine whether an accidently intravascular injection has occurred.

• Other subtle signs of intravascular injection may include a feeling of apprehension, unease, or palpitations. It is important to fractionate the total dose of local anesthetic and observe the patient at 1-minute intervals.

Epidural Analgesia.........

• Patient-controlled epidural analgesia is a safe and effective alternative to conventional bolus or infusion techniques.Maternal acceptance is excellent, and demands on anesthesia manpower may be reduced.

• Initial analgesia is achieved with bolus doses of local anesthetic. Once the mother is comfortable, patient-controlled epidural analgesia may then be started with a maintenance infusion (4–8 mL/h) of local anesthetic (bupivacaine, levobupivacaine, ropivacaine 0.0625–0.125%) with or without opioid (fentanyl 1–2 mcg/mL) sufentanil 0.3–0.5 mcg/mL).

• The machine may be programmed to administer an epidural demand bolus of 4 mL with a lockout period of 10 minutes between doses.

• The caudal rather than the lumbar approach may result in a faster onset of perineal analgesia and therefore may be preferable to the lumbar epidural approach when an imminent vaginal delivery is anticipated.

• However, caudal analgesia is no longer popular because of occasionally painful needle placement, a high failure rate, potential contamination at the injection site, and risks of accidental fetal injection.

• Before caudal injection, a digital rectal examination must be performed to exclude needle placement in the fetal presenting part. Low spinal “saddle block” has virtually eliminated the need for caudal anesthesia in modern practice.

Spinal Analgesia

• A single intrathecal injection for labor analgesia has the benefits of a reliable and rapid onset of neural blockade. However, repeated intrathecal injections may be required for a long labor, thus increasing the risk of postdural puncture headache. In addition, motor block may be uncomfortable for some women and may prolong the second stage of labor.

• Microcatheters were introduced for continuous spinal anesthesia in the 1980s. They were subsequently withdrawn when found to be associated with neurologic deficits, possibly related to maldistribution of local anesthetic in the cauda equina region.

• Fortunately, in a recent multi-institutional study, no cases of neurologic symptoms occurred after the use of 28-gauge microcatheters for continuous spinal analgesia in laboring women.

• Spinal anesthesia is also a safe and effective alternative to general anesthesia for instrumental delivery.

Spinal Opioids Alone• Preservative-free opioids may be given intraspinally as a single injection or

intermittently via an epidural or intrathecal catheter . • Relatively high doses are required for analgesia during labor when spinal opioids

are used alone. • The higher doses may be associated with a high risk of side effects, most

importantly respiratory depression. For that reason combinations of local anesthetics and opioids are most commonly used .

• Pure opioid techniques are therefore most useful for high-risk patients who may not tolerate the functional sympathectomy associated with spinal or epidural anesthesia .

• This group includes patients with hypovolemia or significant cardiovascular disease such as aortic stenosis, tetralogy of Fallot, Eisenmenger's syndrome, or pulmonary hypertension.

• With the exception of meperidine, which has local anesthetic properties, spinal opioids alone do not produce motor blockade or maternal hypotension (sympathectomy). Thus, they do not impair the ability of the parturient to push the baby out.

Disadvantages include less complete analgesia, lack of perineal relaxation, and side effects such as pruritus, nausea, vomiting, sedation, and respiratory depression . Side effects may improve with low doses of naloxone (0.1–0.2 mg/h IV)Intrathecal Opioids-

Agent Intrathecal dose Epidural dose

Morphine 0.25-0.5mg 5mg

meperidine 10-15mg 50-100mg

Fentanyl 12.5-25micro grm 50-150 micro grm

Sufentanil 3-10micro grm 10-20micro grm

Combined Spinal Epidural Analgesia(CSE)

• First described in 1937• This technique has risen in popularity over the last 15 years• Currently being used for Orthopedic, Urologic, and Gynecologic surgeries and for

providing post-op pain relief• Gained much favor in Obstetrics for providing ANALGESIA & ANESTHESIA for labor,

delivery or for C-sections. Techniques-there is two method for CSE1)TWO-LEVEL Technique-The epidural catheter is inserted FIRST and tested so

placement is confirmed• Then the spinal is done at one or two interspaces below the level of the epidural• ADVANTAGE: Able to test Epidural cath prior to spinal injection• DISADVANTAGE: Trauma and discomfort from multilevel insertion2)SINGLE LEVEL INSERTION:First used in 1982, the “needle-through-needle” technique

involves inserting an epidural needle at the appropriate interspace then using the epidural needle as a guide or introducer for the spinal needle

• A small 25 or 27gauge spinal needle can be used since the epidural needle is it’s guide and the tissue has already been penetrated by the first needle

2)SINGLE LEVEL INSERTION………. Once your epidural catheter is placed, ANY FLUID aspirated from it must be assessed

to see if it is CSF1) CSF is warm to the touch if allowed to drip on your forearm2) CSF will form a precipitate if mixed with an equal volume of Sodium Thiopental3) ANY injection via the catheter must ONLY BE DONE after careful and diligent test

aspirations, and you need to aspirate every 3-5cc while giving your epidural doses

ADVANTAGE: Single level insertion associated with less tissue trauma, backache and associated morbidity

DISADVANTAGE: Inability to be able to adequately test the epidural catheter position and function with a pre-existing spinal block since the spinal part of the procedure must go first

CSE NEEDLE- 2 Type needle 1)a modified Tuohy needle with a “Back eye” located at the bend of

the needle, most common one used today . 2) a straight beveled, blunt tipped epidural needle, but there is a

higher incidence of inadvertent dural puncture during placement since it is NOT rounded like the Tuohy

CSE.......• Combined spinal–epidural analgesia is an ideal analgesic technique for use during

labor. It combines the rapid, reliable onset of profound analgesia resulting from spinal injection with the flexibility and longer duration of epidural.

• The most common one used today is a modified Tuohy needle with a “Back eye” located at the bend of the needle.

• Intrathecal injection of fentanyl 10–25 mcg or sufentanil 2.5–5 mcg, alone or in combination with 1 mL of isobaric bupivacaine 0.25%, produces profound analgesia lasting for 60–120 minutes with minimal motor block.

• Opioid alone may provide sufficient relief for the early latent phase, but almost always the addition of bupivacaine is necessary for satisfactory analgesia during advanced labor.

• An epidural infusion of bupivacaine 0.03–0.0625% with opioid may be started within 10 minutes of spinal injection. Alternatively, the epidural component may be activated when necessary.

CSE.....

• Women with hemodynamic stability and preserved motor function who do not require continuous fetal monitoring may ambulate with assistance. Before ambulation, women should be observed for 30 minutes after intrathecal or epidural drug administration to assess maternal and fetal well-being.

• A recent study indicated that early administration of combined spinal–epidural analgesia to nulliparous women did not increase the cesarean section delivery rate.

• The most common side effects of intrathecal opioids are pruritus, nausea, vomiting, and urinary retention. Rostral spread resulting in delayed respiratory depression is rare with fentanyl and sufentanil and usually occurs within 30 minutes of injection.

• Transient nonreassuring fetal heart rate patterns may occur because of uterine hyperstimulation, presumably as a result of a rapid decrease in maternal catecholamines or because of hypotension after sympatholysis.

CSE.....

• fetal bradycardia may occur in the absence of uterine hyperstimulation or hypotension and is unrelated to uteroplacental insufficiency.

• The incidence of fetal heart rate abnormalities may be greater in multiparous woman with a rapidly progressing, painful labor. Most studies have demonstrated that the incidence of emergency cesarean section delivery is no greater with combined spinal–epidural analgesia than after conventional epidural analgesia.

• Postdural puncture headache is always a risk after intrathecal injection. However, the incidence of headache is no greater with combined spinal–epidural analgesia compared with standard epidural analgesia.

CSE.....

• Unintentional intrathecal catheter placement through the dural puncture site is also rare after use of a 26-gauge spinal needle for combined spinal–epidural analgesia.

• The potential exists for epidurally administered drug to leak intrathecally through the dural puncture, particularly if large volumes of drug are rapidly injected. In fact, epidural drug requirements are approximately 30% less with combined spinal–epidural analgesia than with standard lumbar epidural techniques for cesarean section delivery.

• Some clinicians do not advocate the combined spinal–epidural analgesia technique for labor because of the concern for an “unproven” epidural catheter that may need to be used emergently for cesarean section delivery. The patient may have a partial block insufficient for surgery with an epidural that may or may not work.

local anaesthetics used in epidural analgesia in labour pain relief

Local anaesthetic agents and Drug Concentration

Initial dose Top up dose

Lignocaine 0.5% 10 ml 3-5 ml

Bupivacaine 0.125% 10 ml 6-12 ml–hr infusion

Ropivacaine 0.2% 10 ml 8ml-hr infusion

Levobupivacaine 0.125% 10 ml 6-12 ml-hr infusion

Epinephrine-Containing LA Solutions

• The effect of epinephrine-containing solutions on the course of labor is somewhat controversial.

• Many clinicians use epinephrine-containing solutions only for intravascular test doses because of concern that the solutions may slow the progression of labor or adversely affect the fetus; others use only very dilute concentrations of epinephrine such as 1:800,000 or 1:400,000.

• Studies comparing these various agents have failed to find any differences in neonatal Apgar scores, acid–base status, or neurobehavioral

evaluations.

Paracervical Block

• Although paracervical block effectively relieves pain during the first stage of labor, it is now rarely used because of its association with a high incidence of fetal asphyxia and poor neonatal outcome, particularly with the use of bupivacaine.

• This may be related to uterine artery constriction or increased uterine tone.• Paracervical block is a useful technique to provide analgesia for uterine curettage.

The technique is very simple and involves a submucosal injection of local anesthetic at the vaginal fornix near the neural fibers innervating the uterus .

Pudendal Nerve Block The pudendal nerves are derived from the lower sacral nerve roots (S2-4) and

supply the vaginal vault, perineum, rectum, and sections of the bladder.• The nerves are easily blocked transvaginally where they loop around the ischial

spines. Local anesthetic, deposited behind each sacrospinous ligament can

provide adequate anesthesia for outlet forceps delivery and episiotomy repair.

Paravertebral Lumbar Sympathetic Block

• Paravertebral lumbar sympathetic block is a reasonable alternative when contraindications exist to central neuraxial techniques.

• Lumbar sympathetic block interrupts the painful transmission of cervical and uterine impulses during the first stage of labor.

• Although there is less risk of fetal bradycardia with lumbar sympathetic block comparedwith paracervical blockade, technical difficulties associated with the performance of the block and risks of intravascular injection have hampered its routine use.

• Hypotension may also occur with lumbar sympathetic blocks.