Post on 14-Dec-2015
NON-NEURAXIAL TECHNIQUES FOR LABOR ANALGESIAModerator: Dr. Girish
SharmaPresented By: Dr. Arvind Sethi
INTRODUCTION
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.
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 InhalationalTechniques' 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
Parenteral opioid 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:
1. Maternal: Orthostatic hypotension, nausea, vomiting ,delayed gastric emptying,dysphoria,drowsiness,hypoventilation.
2. Fetal: ↓ beat-to-beat variability of FHR.
3. Neonatal: respiratory depression , neurobehavioral changes.
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Systemic opioids for labor analgesia DRUG Usual
dose Onset
DurationComments
Meperidine
25-50mg IV50-100mg IM
5-10min IV40-45min IM
2-3 hrsMax. neonatal depression 1-4 hrs after the dose
Morphine 2-5mg IV5-10mg IM
3-5min IV20-40min IM
3-4 hrs More neonatal depression than meperidine
Diamorphine
5-7.5mg IV/IM
5-10min IM 90 min More euphoria, less nausea than morphine
Fentanyl 25-50ùg IV100úg IM
2-3min IV10min IM
30-60min Less neonatal depresion than with meperidine
Systemic analgesia contd.Nalbuphine
10-20mg IV/IM
2-3 min IV/IM
3-6 hrs Lower neonatal neurobehavioral scores
Butorphanol
1-2mg IV/IM
5-10min IV10-30min IM
3-4hrs Ceiling effect on respiratory depression
Meptazinol
100mg IM 15 minIM 2-3 hrs Less sedation & respiratory depression
Pentazocine
20-40 mg IV/IM
2-3min IV5-20min IM/SC
2-3 hrs Psychomimetic effects possible
Tramadol 50-100mg IV/IM
10 min IV 2-3 hrs Less efficacy & more side effects than meperidine
Intermittent Bolus Parenteral opioid 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 casesGestational age of 37- 42 weeksCervical dilatation ≥ 4cmCervical status: bishop score >6Engaged 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 wayWhen the case is in active phase i.e. os ≥
4cm1) 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 ANESTHESIAPatient-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 buttonBesides i.v., alternative routes for PCA delivery are s.c., oral,transmucosal,nasal,intrathecal,epidural,transdermal
PCA has several modes of administration. Most common ;1) demand dosing (a fixed-size dose is self-administered
intermittently) 2) 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 common1)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
opioid USED FOR PCA DRUG Patient
Controlled Dose
Lockout interval
Meperidine 10-15mg 8-20min
Nalbuphine 1-3mg 6-10min
Fentanyl 10-25úg 5-12min
Remifentanil (bolus)(background infusion with bolus dose)
0.4-0.5úg/kgInfusion rate0.05úg/kg/minBolus;0.25úg/kg
2-3min
INHALATIONAL ANALGESIAPRINCIPLE 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
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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
Drawover oxford Miniature vapouriser
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 Complications1)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.
NON-PHARMACOLOGIC ANALGESIA
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.
Intra-dermal Water Injections
Intra-dermal water injections are used to treat lower back pain which is a common complaint during labor
The afferent nerve fibres that innervate the lower back, enter the spinal cord at T10 through L1 spinal segments.
Technique: approx. 0.05-0.1 ml of sterile water is injected intradermally to form a small bleb over each posterior superior iliac spine on both sides & at 3cm below & 1cm medial to each spine(Four injections)
cts the injections themselves are acutely painful for about 20-30 seconds, but as the injection pain fades. so does the lower back pain.
A simple method of reducing severe low back pain without adverse effects on mother and fetus
Transcutaneous Electrical Nerve Stimulation (TENS)
Involves transmission of low-voltage electrical current to surface electrodes placed over lower back in the region of T10-L1
Reduces pain by nociceptive inhibition at a presynaptic level in dorsal horn by limiting central transmission.Electrical stimulation activates low-threshold myelinated nerves.
Afferent inhibition inhibit propogation of nociception along unmyelinated small “c” fibres by blocking impulses to target cells in substantia gelatinosa of the dorsal horn.
TENS also enhances release of endorphins and dynorphins centrally.
Acupuncture/Acupressure Four randomized control trials found that pain
score were lower in women randomized assigned to receive acupuncture treatment, as was the rate of use of other modes of analgesia. A shorter duration of the active phase of labor and a reduction in use of oxytocin in acupuncture group was observed.
Hypnosis Limitations; Ante partum training sessions are required. Trained hypnotherapist must be available during
labor Offers no clear benefit
Childbirth preparation classes and non-pharmacologic analgesic techniques are not comparable with regional analgesia techniques for relief of labor pains. So whether it is useful for anesthetist to have knowledge of these techniques? Our active participation in the childbirth education classes may help patients receive more accurate information about the risks and benefits of analgesia/anesthesia for labor, vaginal delivery. We can encourage instructors to prepare pt. for the unexpected as “Typical labor” may infact be atypical. Thus patients will perceive anesthetist as an integral part of obstetric team.
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