NON-NEURAXIAL TECHNIQUES FOR LABOR ANALGESIA. Moderator: Dr. Girish Sharma Presented By: Dr. Arvind Sethi.
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NON-NEURAXIAL TECHNIQUES FOR LABOR ANALGESIA Moderator: Dr. Girish Sharma Presented By: Dr. ArvindSethi
labor pain is one of the most intense pain a women can experience.Efforts have been taken for centuries to remove the labor pain, but it has never been easy in the past as it is in the present. While neuraxial analgesia is the gold standard for achieving complete analgesia in labor, many women do not desire such high-tech pain relief. Many women want to ‘Cope with pain of labor ‘ rather than anhilate the pain completely. For many of these women non-neuraxial techniques will suffice. INTRODUCTION
The Physiology of Pain in Labor • 1st stage of labor – mostly visceral • Dilation of the cervix and distention of the lower uterine segment • Dull, aching and poorly localized • Slow conducting, visceral C fibers, enter spinal cord at T10 to L1 • 2nd stage of labor – mostly somatic • Distention of the pelvic floor, vagina and perineum • Sharp, severe and well localized • Rapidly conducting A-delta fibers, enter spinal cord at S2 to S4 T10 L1 S2 S4 http://www.manbit.com/oa/oaindex.htm
The Intensity of Pain in Labor http://www.manbit.com/oa/oaindex.htm
NON-NEURAXIAL LABOR ANALGESIA Pharmacological Non-Pharmacological • Systemic analgesia Parenteral Inhalational Techniques' alternative to regional anesthesia Paracervical block Pudendal block • Minimal Training/Equipment • Continuous labor support • Touch and massage • Therapeutic use of heat and cold • Hydrotherapy • Vertical position • Specialized Training/Equipment • Intradermal water injections • Transcutaneous Electrical Nerve Stimulation • Acupuncture/Acupressure • Hypnosis
Parenteralopioid analgesia • opioid are the most widely used systemic medications for labor analgesia. • Their use does not require specialised equipment or personnel. • Allows the parturient to better tolerate the pain of labor. • Little scientific evidence suggests that one drug is better than other. • Selection of an opioid is based on institutional tradition/personnel preference • Efficacy and incidence of side effects are largely dose dependent rather than drug dependent
Analgesia (contd) • Although narcotics provide both analgesia & sedation, their S.E are: • Maternal: Orthostatic hypotension, nausea, vomiting ,delayed gastric emptying,dysphoria,drowsiness,hypoventilation. • Fetal: ↓ beat-to-beat variability of FHR. • Neonatal: respiratory depression , neurobehavioral changes.
Intermittent Bolus Parenteralopioid Analgesia • Given intermitently via s.c ,i.m, i.v route(preferred) • Faster onset of analgesia • Ability to titrate dose to effect
MEPERIDINE • Most commonly used opioid for labor analgesia • 100 mg i.m repeated once after 4 hrs • Onset ;45 min • Readily crosses placenta by passive diffusion & equilibrates b/w maternal and fetal compartments in 6 minutes • Fetal exposure to meperidine is highest b/w 2-3 hrs after maternal administration(more respiratory depression in neonates born within 2-3 hrs) • Causes less respiratory depression in neonate than morphine • Metabolised in liver to normeperidine which crosses the placenta & is also formed as a result of fetal and neonatal metabolism( half life = 60 hrs in neonate)
Meperidine contd. • Effect on progress of labor is contentious Some obstetricians say that it may prolong the latent phase of labor, others administer it to shorten the length of first stage in cases of dystocia • Sosa et al. concluded that meperidine does not benefit women & should not be used in labor with dystocia because of adverse neonatal outcome
MORPHINE • Currently morphine is infrequently prescribed in labor • Significant analgesic but respiratory depressant • Rapidly crosses the placenta and a fetal to maternal plasma conc. ratio of .96 is observed at 5 min. • Elimination half life is longer in neonates than in adults • Crosses BBB more in fetus • Greater plasma clearance, shorter elimination half life, earlier peak metabolite levels occur due to changes in pharmacokinetics during pregnancy
Diamorphine • A synthetic derivative of morphine • Rapid, effective analgesia with less nausea & vomiting but more euphoria than morphine • Crosses placenta & associated with respiratory depression
FENTANYL • Synthetic opioid with analgesic potency • 100 times that of morphine • 800 times that of meperidine • Rapid onset, short duration of action, lack of active metabolite make it attractive for labor analgesia • Average umbilical –to-maternal conc. ratio remains low at 0.31 • The researchers found less sedation, vomiting,no adverse effect on APGAR score or fetal acid-base status
NALBUPHINE • Mixed agonist-antagonist opioid analgesic • Potency and respiratory depression are similar with morphine at equianalgesic dose • Ceiling effect on respiratory depression with increasing dose(max. with 30mg dose) • Mean umbilical vein-t0-maternal conc. ratio is higher with nalbuphine than with meperidine • less nausea, vomiting but more maternal sedation than meperidine
BUT0RPHANOL • opioid with agonist-antagonist properties • 5 times as potent as morphine & 40 times as potent as meperidine • Respiratory depression with butorphanol , morphine,meperidine (2mg) = (10mg) (70mg) • (4mg) < (20mg) (140mg) • Butorphanol(1-2mg) when compared with meperidine(40-80mg) for labor analgesia , it has less maternal side effects, better analgesia at 30min and 1 hour with no difference in APGAR score.
Butorphanol(cont.) • Butorphanol offers analgesia with some sedation( similar to meperidine+ phenothiazine) • Shorter half life and inactive metabolite. • Favorable neonatal neurobehavioral outcome • A USEFUL AGENT FOR LABOR ANALGESIA
MEPTAZINOL • Partial opioid agonist with less sedation, resp. depression, dependence • Neonatal half life =3.4 hrs • Higher APGAR score at 1min • Limitations; Higher Cost & Availability
PENTAZOCINE • Synthetic opioid , both agonist and weak antagonist • 30-60mg equipotent as 10mg morphine • Ceiling effect on respiratory depression occurs at 40-60mg • Limitation ;Psycho mimetic effect at higher doses
TRAMADOL • Atypical, weak synthetic opioid • Potency 10% that of morphine • No respiratory depression • More nausea • Analgesia not superior to meperidine
PROGRAMMED LABOR(Modern management of labor) Criteria for selection of cases • Gestational age of 37- 42 weeks • Cervical dilatation ≥ 4cm • Cervical status: bishop score >6 • Engaged head & adequate pelvis • No pregnancy induced complication like APH or medical disorders like Heart disease, DM, HTN, Jaundice.
Programmed labor(contd.) • Labor is programmed in the following way • When the case is in active phase i.e. os≥ 4cm 1) LR (500ml) with 2.5U oxytocin started such that contractions ≥3 per 10min lasting for 20-40 sec. 2) ARM done. 3) 2mg of diazepam (1ml) & 6mg of pentazocine(2ml) diluted with 7ml of normal saline, so that total solution is 10ml. Total 2ml of the solution is given slow iv. Remaining 8ml added to iv fluid post-partum during repair of tear or episiotomy. 4) Inj. drotaverine & tramadol given i.v. and repeated as required. 5) Partographic management of labor is done
Active management of labor with oxytocin, amniotomy and spasmolytic and labor analgesia with tramadol,diazepam & pentazocine is safe, convenient and acceptable. • Marked labor analgesia. • There is marked reduction of the total duration of labor. • Marked in LSCS rate. • Minimum side effects on mother. • No effect on of apgar score of fetus
PATIENT CONTROLLED ANESTHESIA Patient-controlled analgesia (PCA) is commonly assumed to imply on-demand, intermittent, IV administration of opioid under patient control (with or without a continuous background infusion). This technique is based on the use of a sophisticated microprocessor-controlled infusion pump that delivers a pre-programmed dose of opioid when the patient pushes a demand button Besides i.v., alternative routes for PCA delivery are s.c., oral,transmucosal,nasal,intrathecal,epidural,transdermal
PCA has several modes of administration. Most common ; demand dosing (a fixed-size dose is self-administered intermittently) continuous infusion plus demand dosing (a constant-rate fixed background infusion is supplemented by patient demand dosing) All modern PCA devices offer both modes. Less common 1)Infusion demand ( successful demands are administered as an infusion) 2) preprogrammed variable-rate infusion plus demand dosing ( the infusion rate is preprogrammed on an interval clock to vary or turn off altogether by time of day) 3) variable-rate feedback infusion plus demand dosing (microprocessor monitors demands and controls the infusion rate accordingly) .
Advantages of PCA • Superior pain relief with lower doses of drug • Less risk of maternal respiratory depression • Less placental transfer of drug • Less need for anti-emetic agents • Higher patient satisfaction
Limitations • Despite frequent administration, small doses of opioid may not be effective for fluctuating intensity of labor pain • Risk to fetus & neonate remains unclear • Variable doses & lockout intervals have been used • Most appropriate drug, dose ,dosing schedule have not been defined
INHALATIONAL ANALGESIA PRINCIPLE • An attractive option since pregnancy causes decreased FRC increased minute ventilation Rapid equilibration b/w inspired and alveolar conc.of inhaled agent • Features of inhalational agent that make it suitable for labor analgesia are related to 1) Nature of labor pain: pain is felt 10-20 sec. after onset of uterine contraction & lasts for 40-60 sec. 2) Blood gas solubility: low inhalation at onset of contraction results in analgesic blood levels which rapidly falls out at the end of contraction
INHALATIONAL ANALGESIA ENTONOX: NITROUS OXIDE(50%)+ OXYGEN(50%) • Provides partial pain relief during labor as well as at delivery. • 50% N2O in O2.(Pre-mixed in a blender)Poynting effect involves dissolution of gaseous O2 bubbled through liquid N2O with vaporization of liquid to form gaseous mixture. • It’s administered with a mask / mouthpiece in a manner such that the parturient remains awake, cooperative & in control of her airway to prevent pulmonary aspiration of gastric contents. • Does not prolong labor or interfere with uterine contractions but administration > 20 minutes may result in neonatal depression. • Dec. risk of neonatal depression when compared with narcotics.
Instruct pt. to inhale deep in b/w the contraction • Inhale 30 sec. before the next anticipated contraction & cease with receding of contraction • In b/w mask may be removed which is held by pt. • Inform that total relief of pain will not occur but gas will provide some relief • IV line, pulse oximetry • Methoxyflourane, Enflurane,Isoflurane do not have any adv. over nitrous oxide
SEVOFLURANE • MOST COMMONLY USED VOLATILE HALOGENATED AGENT • 0.8% sevoflurane is optimal conc. for labor analgesia • Investigators concluded that sevoflurane can provide useful analgesia for labor & is superior to Entonox • Initial studies of intermittent sevoflurane are promising , but larger studies are needed to assess the incidence of maternal compromise
PARACERVICAL BLOCK • Provides satisfactory pain relief during first stage • Goal: to block paracervical(Frankenhauser’s) ganglion which is immediately lateral & posterior to cervicouterine junction • Does not adversely affects labor • provides good analgesia in first stage without the annoying sensory & motor blockade • Does not relieve pain during late first stage& second stage of labor
Technique: • Patient in modified lithotomy position(pillow below pt.’s right buttock to correct dextrorotation of uterus • Use a needle guide to define & limit the depth of injection & to reduce the risk of vaginal & fetal injury • Introduce needle & needle guide into left/right lateral vaginal fornix at 4’0’ clock or 8’0’ clock position (with left hand for left and right hand for rt. side. • Needle is advanced through vaginal mucosa and to a depth of 2-3mm • 5-10 ml of local anesthetic(without epinephrine) is injected on each side
Maternal complications • Vasovagal syncope • Lacerations of vaginal mucosa • Systemic local anesthetic toxicity • Parametrial hematoma • Postpartum neuropathy • Paracervical or subgluteal abscess
Fetal Complications 1)Fetal injury from direct injection of LA into fetal scalp(advanced labor>8cm) leading to systemic toxicity 2)Fetal Bradycardia in 15% cases because of • drug induced uterine artery vasoconsriction,CNS depression. myocardial depression • decreased placental perfusion because of uterine hypertonia as a result of post paracervical block causing increase in uterine activity • Manipulation of fetal head,uterus,uterine vessels produce reflex bradycardia
PUDENDAL BLOCK • Goal is to block the pudendal nerve distal to its formation by the ant. division of S2-S4 but proximal to its division into branches. • Provide satisfactory anesthesia for vaginal delivery & outlet forceps application • Administered shortly before delivery • Analgesia produced in lower birth canal & perineum provides maternal comfort for low forceps delivery & episiotomy. • Advantages: easy to administer, not a/w maternal hypotension/ fetal distress. • Disadvantage: incomplete analgesia at the time of delivery, since pain of uterine contraction is unaffected
Technique • Transvaginal—preffered • Transperineal • A tubular introducer is placed against vaginal mucosa just beneath the tip of ischial spine • A 15cm ,22G needle is pushed through introducer 1-1.5cm beyond the introducer into the mucosa • 1ml of 1% lignocaine is injected into mucosa after aspiration • Sacrospinous ligament is infiltrated with 3ml of lignocaine • 3ml is injected into loose areolar tissue behind the sacrospinous ligament • needle is withdrawn into introducer & moved to just above the ischial spine & rest of 10ml is injected into mucosa
Pudendal block(cont.) • within 3-4 min successful block is achieved(allows pinching of lower vagina & posterior labia without pain and loss of anal reflex • COMPLICATIONS • Intravascular injection • Hematoma from perforation of blood vessels • Secondary infection at the injection site which may spread to hip joint, gluteal muscles.
Continuous Labor Support • Patient’ sense of isolation adversely affects her perception of labor. • A meta-analysis evaluated results from 16 studies that included more than 13000 women who were randomly assigned to receive either continuous labor support or usual care .Women who received one-on one support were less likely to use any type of analgesia & were more likely to have short labor, spontaneous vaginal delivery and were better satisfied.
Touch & Massage • Effleurage, Counter pressure to alleviate back discomfort, light stroking, and merely a reassuring pat. • Therapeutic use of heat & cold • Warm compresses on localized areas of body • Ice packs on low back or perineum to decrease pain perception
Hydrotherapy • Simple shower or tub bath or a whirlpool or large tub specially equipped for pregnant women. • Decreases anxiety and pain and increases uterine contraction efficiency
Vertical position • INCLUDE • Sitting, Standing, Walking, Squatting • women reported less pain in vertical positions than in horizontal positions(supine,lateral) • Walking neither enhanced nor impaired active labor & was not harmful to mothers or their infants.