Analgesia and Anesthesia in Obstetrics Husam Qawasmeh

Outlines  Labor pain.  Analgesia in labor.  Anesthesia in labor.

Labor Pain  Labor pain is one most severe pain human can experience (as they said)  Greatly variable and is often dictated by a woman’s emotional, motivational, cognitive and cultural circumstances..  Often have to “tailor” anesthetic to meet individuals requirements.  McGill pain questionnaire.  There is no evidence that pain relieving improves the labor  There is no evidence that pain relieving improves the labor Outcome. Yes, It hurts!!

Source of labor pain 1 st stage ◦Uterine contraction s which cause myometrial ischemia. ◦Cervical dilatation. ◦Dull, aching and poorly localized ◦Slow conducting, visceral C fibers, enter spinal cord at T10 to L1 2 nd stage ◦ 1-Uterine contractions ◦ 2-Stretching of the vulval orifice ◦ 3-Pressure on the pelvic floor ◦Sharp, severe and well localized ◦Rapidly conducting A-delta fibers, enter spinal cord at S2 to S4

Labor Pain at different Stages of Labor Eltzschig, Leiberman, Camann, NEJM 348; 319:2003

Pathways of Pain during Labor  Stage I – governed by T10 – L1  Through Hypogastric and Pre-aortic plexuses.  Stage II – governed by, 1-Pudendal N S2-S4 2-Genitfemoral N L1-L2 3-Post. Femoral cutaneous N S1-S3  Often requires local anesthetic to adequately control pain.

Pain Progression & Labor Progression

Factors that increase labor pain Physical 1- Uterine contraction intensity and duration. 2- Fetus size. 3- Insufficient relaxation of the vaginal and vulval walls, etc….. Psychological 1-Fear 2-Anxiety 3-Degree of support 4-Stress

Adverse effect of labor pain Maternal sensation of discomfort Maternal hyperventilation causing: ◦Respiratory alkalosis ◦Shift of oxyhemoglobin dissociation to the left. ◦Decrease oxygen offloading to the fetus.

Options for labor pain relief Non-pharmacologic. Pharmacologic.

Nonpharmacologic Psychoprophylaxis (Lamaze method): Emphasized relaxation coupled with a variety of patterned breathing techniques and focused attention on fixed object Emotional support. Massage. Warm water baths.

Transcutaneous Electrical Nerve Stimulation (TENS). (works on blocking pain fibers in the posterior ganglia of the spinal cord). Hypnosis. Acupuncture. There is no definitive evidence that any of these techniques effectively relieves labor pain or improves labor outcome. These techniques tend to work best early in the first stage of labor when the pain is least intense. Cont …

Analgesics vs. Anesthetics There are two types of pain-relieving drugs — analgesics and anesthetics. Analgesia is the relief of pain without total loss of feeling or muscle movement. Analgesics do not always stop pain completely, but they do lessen it. Anesthesia is blockage of all feeling, including pain. Some forms of anesthesia, such as general anesthesia, cause you to lose consciousness. Other forms, such as regional anesthesia, remove all feeling of pain from parts of the body while you stay conscious. In most cases, analgesia is offered to women in labor or after surgery or delivery, whereas anesthesia is used during a surgical procedure such as cesarean delivery.

Options of analgesia during Labor Systemic medication Easy to administer, but risk of maternal or neonatal depression opioids most commonly used if delivery not expected within 4 hours because they may slow the baby’s reflexes and breathing at birth. Inhalational analgesia (GA) Easy to administer, makes uterine contractions more tolerable, but does not relieve pain completely 50% nitrous oxide Regional anesthesia (epidural, spinal block, combined epidural- spinal) LA Provides excellent analgesia with minimal depressant effect Hypotention is the most common complication Epidural usually given as it preferentially blocks sensation, leaving motor function intact

Options for caesarean section  will depend on the mother health and the baby health. It also depends on why the cesarean delivery is being done.  Regional: spinal or epidural  General: used if contraindications or time precludes (emergency or bleeding) regional blockade.

Systemic medications

Pharmacological Methods Meperidine (pethidine )  synthetic phenylpiperidine derivative which is commonly administered intramuscularly (IM) in a dose of 1mg /kg.  Analgesia is maximal 45 minutes post injection  delays gastric emptying,  increase gastric volumes in labor.  causes sedation  dose-dependant respiratory depression  its active metabolite (nor-meperidine) has convulsant properties.  crosses the placenta and its effects on the fetus are dependant on dose and timing of administration Despite these disadvantages, Meperidine remains popular in many obstetric units

Morphine shares many of the side effects of meperidine and rapidly crosses the placenta its metabolites do not have convulsant effects. The dose used for maternal analgesia is 0.1 – 0.15mg/kg.

Fentanyl  highly potent phenylpiperidine derivative  has a rapid onset of action  It has a longer terminal half life than both meperidine and morphine  repeated dosing may result in drug accumulation in both the fetus and the mother.  Advantages include: 1.absence of active metabolites and 2.rapid onset of action making it 3.useful for patient-controlled analgesia.

Patient-controlled analgesia (PCA) If regional analgesia is unavailable or contraindicated, then PCA is a useful method of pain control as long as the equipment and staffing are available. PCA provides some control to the woman, and this in itself is associated with greater satisfaction; however it is important that women are instructed in how to use the device effectively. Many opioids have been used in PCA devices; drugs currently used include fentanyl and more recently remifentanil. A suggested regimen for fentanyl PCA is 20 μg bolus with 5 min lockout, however the ideal loading dose, bolus dose, lockout time and maximum hourly dose remain unclear. Both parturient and neonate should be carefully monitored during labour & post-partum and PCA settings altered accordingly.

Remifentanil an ultra short acting opioid, rapidly hydrolysed by blood and tissue esterases does not accumulate even after prolonged infusions. There are increasing reports of its use in PCA though like fentanyl, the ideal regimen remains unclear. A bolus dose of μg Kg with 2 minute lock-out has been used successfully. close monitoring is essential and supplementary oxygen may be required.

Intrathecal Opioids Intrathecal Opioids provide better analgesia than parenteral opioids, they: ◦Provide rapid onset of relief. ◦Can have a long duration of action. ◦Typically cause no degree of motor blockade. ◦Routinely cause no effect on the fetus.

 More effective than opioids and is widely used.  Most commonly used mixture is Entonox (an equal mixture of NO & Oxygen).  Provides quick with short duration of effect.  Not suitable for prolonged use from early labor, so most suitable is late in labor or while awaiting epidural analgesia.  Adverse effects include nausea & light headedness. Inhalational Anesthesia

Types of anesthesia  Local involves any part of the body.  General causes lack of sensation of the entire body.

Preparation for anesthesia  Informed consent.  Equipments for airway management and resuscitation.  Monitors (blood pressure, heart rate and ECG)  Preanesthetic assessment (CVS, RES,…, etc)  IV large bore canula.

General anesthesia  When dealing with general anesthesia in pregnant lady we have to bear in mind some physiological changes which might affect our choice of GA administration in pregnant lady.

Physiological changes in pregnancy  Respiratory system : (1) Increase o2 consumption by 60%. (1) Increase o2 consumption by 60%. (2) Decreased functional residual capacity resulting in a lower store of oxygen. (2) Decreased functional residual capacity resulting in a lower store of oxygen. (3) 8 times increase the risk of failure of intubation. (3) 8 times increase the risk of failure of intubation.

Gastrointistinal system  Pressure made by enlarging uterus lead to increase in intra gastric pressure which may lead to gastric reflux, and increasing the incidence of pulmonary aspiration of gastric contents.

General anesthesia  GA isn’t used in vaginal delivery.  GA Used in C/S in certain circumstances.  GA increases the risk of aspiration.  Extreme emergency situations.  any contraindication for regional anesthesia e.g infection at needle insertion site, prior back surgery, increase intracranial pressure, etc.  Failure of regional anesthesia.  Unexpected prolonged surgery.

Benefits of GA  Help the obstetrician to deliver the baby that is distressed.  Situation where minutes may count for the fetus such as ruptured uterus, placental abruption, umbilical cord prolapse.  Situations where rapid induction maybe needed for maternal safety include uncontrolled hemorrhage as in cases of : placenta previa, trauma, placental abruption, ruptured vessels.

Local Anesthesia Local anesthesia provides numbness or loss of sensation in a small area. It does not, however, lessen the pain of contractions. A procedure called an episiotomy may be done by your doctor before delivery. An episiotomy is a surgical incision used to enlarge the vaginal opening to help deliver a baby.

Local anesthesia is helpful when an episiotomy needs to be done or when any vaginal tears that happened during birth are repaired. Local anesthesia rarely affects the baby. There usually are no side effects after the local anesthetic has worn off.

Though rare, local anesthesia may be injected into the perineum when the baby’s head position will not allow a pudendal block to be administered. This will ease the pain of the perineum stretching, but will not relieve the discomfort of contractions during labor.

Local anesthesia is injected into a specific area to provide pain relief. Local anesthesia is given through various medications and dosages in the form of: 1. Epidurals 2. Pudendal blocks 3. Spinal blocks

When used at the end of birth or after birth, medication such as procaine (Novocain), lidocaine (Dalcaine, Dilocaine, L-Caine, Nervocaine, Xylocaine), and tetracaine (Pontocaine), is injected into the skin, muscle, or cervix for the fast, temporary relief of pain in the perineal area.

Paracervical block Labor pain can be effectively blocked by interrupting the transmission of pain sensation as it passes through or close to the cervix. This is called a paracervical block. Up to 20cc of 1% Lidocaine is used. 10 cc is injected on each side of the cervix, usually in divided doses, at 10 o'clock, 8 o'clock, 2 and 4 o'clock (5 cc in each site). Usually within 5 minutes, the patient becomes completely pain free. The block will last minutes and can be repeated.

Paracervical block  The block is effective when lidocaine reaches the broad ligament.  Injections directly into the cervix may block some pain associated with dilation, it will fail to block the pain of the uterus contracting.  In theory, you should be able to have a single injection site on each side of the cervix and the block will be effective.  In practice, there is enough anatomic variation from person to person over the precise location of the broad ligament that experienced physicians typically will use divided doses to insure that at least some of the drug will get to where it's supposed to go.  Proven to cause fetal bradycardia

Paracervical block The nerves conducting the pain of labor pass next to the cervix. Blocking nerve conduction at this point blocks labor pain.

Paracervical block Inject a total of 20 cc of 1% Lidocaine into the lateral vaginal fornices, with injection sites of 10, 8, 2, and 4 o'clock (5 cc in each site).

Pudendal block

Pudendal block gets its name because a local anesthetic such as, lidocaine or chloroprocaine, is injected into the pudendal canal where the pudendal nerve is located. This allows quick pain relief to the perineum, vulva, and vagina. A pudendal block is usually given in the 2 nd stage of labor just before delivery of the baby.

It relieves pain around the vagina and rectum as the baby comes down the birth canal. It is also helpful just before an episiotomy. Lidocaine is usually preferred for a pudendal block because it has a longer duration than chloroprocaine which usually lasts less than one hour.

A pudendal block may involve one or more of the following risks: Large doses of local anesthesia may be needed to experience relief Local anesthesia medications enter the blood stream and cross the placenta Some babies have trouble breastfeeding immediately after birth Risk of local anesthetic toxicity Risk of a hematoma (blood clot) Risk of infection

Introduction  Epidural (extradural) analgesia is the most reliable means of providing effective analgesia in labor (in 1 st & 2 nd stages of labor)..  The woman must be informed about the risks & benefits, & the final decision in most cases rests with the woman unless there’s a definite contraindication.  Risks: 1.Temporally loss of sensation & movement in her legs. 2.IV access & a more invasive level of maternal & fetal monitoring will be necessary.

 No direct effect on fetus & doesn’t cross placenta.  Epidural analgesia doesn’t increase CS rates. 2 nd stage is longer greater chance of instrumental delivery  However, 2 nd stage is longer & there’s a greater chance of instrumental delivery, which may be lessened by a more liberal use of oxytocin infusions during 2 nd stage in primi- parous women with an epidural. may assist vaginal delivery  Epidural in the 2 nd stage of labor may assist vaginal delivery by relaxing the woman & allowing time for the head to descend & rotate.

 ANALGESIA Continuous Infusion 0.125% (10-20 mL/hr). Boluses. PCEA (Pt-Controlled Epidural Analgesia). Bupivacaine: 0.125%-0.375%, 5-10 ml, duration:1-2 hr Ropivacaine: 0.125%-0.25%, 5-10 ml, duration: 1-2 hr Lidocaine: 0.75%-1.5%, 5-10 ml, duration: hr

 Analgesia for Labor & vaginal delivery necessitates a block from T10-S5 dermatomes.  For CS, a block extending from T4-S1 dermatomes is desired.  Spread of anesthetic depends upon: 1.Location of catheter tip. 2.The dose. 3.Concentration & volume of anesthetic agent. 4.Whether the mother is head-down, horizontal, or head-up.

Indications 1.The main indication 1.The main indication is >> for Effective pain relief. 2.Prolonged labor. 3.Maternal hypertensive disorder. 4.Multiple gestation. 5.Certain maternal medical conditions. 6.When there is high risk of operative intervention. 7.High risk fetus group.

Contra-Indications 1.Pt refusal. 2.Coagulation disorders. >large hematoma & subsequent spinal cord compression after a traumatic bleeding into epidural space. 3.Local or sys. infection. >E.x.: skin infection may introduce pathogenic bacteria into epidural space > meningitis, epidural abscess, … 4.Hypovolemia. >with the sympathetic blockade produced by epidurals >> may cause profound circulatory collapse. 5.Insufficient # of trained staff

It’s important to assess: 1.Rate of the progress. 2.Anticipated length of time to delivery. 3.Type of delivery expected.  It’ll limit mobility >> it’s not ideal for women in early labor.  Also, advanced cervical dilatation isn’t necessarily a contraindication.

Complications  Maternal: - Immediate. - Delayed.  Fetal: >> No direct adverse effect on fetus. >>Studies are still being assessed on long term brain development in children associated with learning disabilities. >>Studies are still being assessed on long term brain development in children associated with learning disabilities. >> Fetal distress can occur if maternal hypotension occurred.

Immediate 1.Hypotension & decreased CO.  How? By blocking sympathetic tracts.  Most common SE & is severe enough to require tt in 1/3 rd of women.  Minimized by Maintaining a lateral position (compared with supine position).  Can be prevented by rapid infusion of mL of crystalloid solution, sympathomimetic drugs such as Ephedrine. Supine Hypotension Syndrome Compression of the Inferior Vena Cava & Aorta with Supine Positioning Uterine Displacement is an important maneuver to relieve it! Decreased blood pressure associated with supine positioning

1.Complete motor & sensory paralysis. 2.Spinal Epidural Heamatoma 3.Intrapartum Fever 4.Repiratory Depression 5.Local anesthetic induced convulsions. >> uncommon but serious complication. 6.Local anesthetic induced cardiac arrest

Delayed 1.Post dural puncture headache.  The needle used is of a wide bore >> may result in leakage of CSF & results in headache.  On top of the head / usually postural; relieved by lying down & exacerbated by sitting upright.  Resolves in 7-10 days if untreated, caffeine or oral analgesics  tt is EBP (Epidural Blood Patch); ml of pt’s own blood will be injected into the epidural space at the level of epidural catheter.  If untreated; may lead to CN palsies. severe, disabling fronto-occipital headache with radiation to the neck and shoulders. present 12 hours or more after the dural puncture worsens on sitting and standing relieved by lying down and abdominal compression.

1.Backache (not proven). 2.Urinary retention; To avoid this a catheter is placed early. 3.Shivering is a common event---Heatead Blankets 4.Tingling in hands or fingers. 5.Epidural abscesses; extremely rare. Meningitis in cases of spinal anesthetic 6.Postpartum Neuropathy 7.Effect on Breastfeeding (inconclusive)

Technique  Spinal cord extend to L2, Dural sac to S2.  Nerve root (cauda equina) from L2 to S2.  Needle inserted below L2 ( L3,L4 or L4,L5)

 Catheter is inserted 6-7 cm beyond tip of the needle, then needle is withdrawn.  Catheter is pulled back such that 4-5 cm of it is left in the space.  Catheter must then be aspirated to make sure that it hasn’t entered the subarachnoid space or an epidural vein. Aspiration should be -ve for CSF or blood. ** If the catheter is in:  Subarachnoid space >> pt complain of severe numbness in LL & BP will decrease.  Epidural vein >> the epinephrine contained in the test dose will cause palpitations, tachycardia, & hypertension.  Correctly into the epidurals space >> none of the untoward symptoms should occur.

 A test dose is given to confirm the catheter position, if no unwanted signs is observed after 5 min of injection, a loading dose can be administered.  A test dose is a vital step in establishing proper placement of epidural catheter.

 Analgesia is maintained by intermittent boluses of similar volume, or small volumes of the drug are delivered continuously by infusion pump.  The rationale for opiate (Fentanyl) use during labor is to avoid motor block by allowing reduction in the dose of local anesthetic.  They are also instructed to switch sides every hour to facilitate the spread of the local anesthetic.  Appropriate resuscitation equipment & drugs must be available during administration of epidural analgesia.

Spinal anesthesia

Introduction of a local anesthetic into the subarachnoid space…Intrathecal A short procedure time. Rapid onset of the block, and limited duration of action. High success rate. Used very late in labor. spinal anesthesia

 Vaginal Delivery, a popular form of analgesia for forceps or vacuum delivery.  T10 dermatome, umbilicus.  excellent relief from the pain of uterine contractions.  Lidocaine is an excellent choice.  Preanalgesic intravenous hydration with 1 L of crystalloid solution to minimize hypotensive effect  Cesarean Delivery, requires a T4 sensory level dermatome. Spinal anesthesia

Indication for spinal anesthesia (1)Operations below umbilicus (2)Any operation in perineum or genitalia (3)All possible operation on the leg except amputation (4)Very important to notice that spinal anesthesia is indicated for older patient with systemic disease.

Contraindication  Patient refusal, uncooperative patients  Hypovolemia  Clotting disorders  Septicemia  Anatomical deformities in the patient back  Neurological disease  Inadequate resuscitative drug and equipments

Complication of spinal anesthesia  Hypotension, bradycardia if block reachs T2- T4.   HIGH SPINAL BLOCKADE.  Post spinal headache (post dural)  Failure of technique.  Epidural or subarachnoid hematoma  Spinal cord trauma or infection  Urinary retention  Rarely, convulsions and blindness

Combined Spinal Epidural (CSE) Initial reports: two interspace technique-epidural followed by spinal Later evolution of CSE in the direction of needle through needle technique Postdural puncture headache: 1% or less incidence for CSE with small bore atraumatic needles.

Advantages in CSE in Labor Analgesia Rapid onset of intense analgesia (the patient loves you immediately!) Ideal in late or rapidly progressing labor Very low failure rate Less need for supplemental boluses Minimal motor block (“walking epidural”)

Anesthesia for Cesarean Section

The choice of anesthesia depend on: The indication for the CS The urgency of the procedure The medical condition of the mother and the fetus The desire of the mother

Spinal Cesarean - bupivacaine is most commonly used. Small doses of intrathecal fentanyl (eg, 15 mcg) may be used to prolong the duration of spinal anesthesia for cesarean Epidural Cesarean -2% Lidocaine with epinephrine is the most common anesthetic for cesarean. Sodium bicarbonate may be added to speed its onset of action % Bupivacaine or Ropivacaine have a much slower onset than Lido, but decrease risk of cardiac toxicity. -Fentanyl and morphine also result in good analgesia CSE Cesarean Standard spinal bupivacaine mg adding the intended dosing of the epidural

Neuroaxial is preferred over GA unless c/I coagulopathy profound maternal hypovolemia certain maternal medical conditions urgency for the procedure due to fetal status patient refusal of neuraxial anesthesia

Anesthesia for Cesarean Section GA associated with higher risk of airway problems. Incidence of failed tracheal intubation in pregnant women is 1 in 200 to 1 in 300 cases Anesthesia2000;55:690-4 Maternal death due to anesthesia is the sixth leading cause of pregnancy related death in USA Obstet Gynecol 1996;88:161-7

Anesthesia for Cesarean Section The risk of maternal death from complications of GA is 17 times as high as that associated with Regional anesthesia In USA the shift from GA to RA for CS resulted in decrease in anesthesia related maternal mortality from 4.3 to 1.7 per 1 million live birth Anesthsiology 1997;86:277-84

Thank You