Labor analgesia

labor analgesia

1. LABOR ANALGESIA Moderator: Dr. Rejin K. Udaya Presenter: Dr. Kundan Kishor Ghimire

2. Objectives Pain pathways during different stages of labor Various methods of labor analgesia Technique for the Epidural analgesia for painless delivery Indication, contraindication benefits and complication of epidural analgesia.

3. Introduction Labor defined as spontaneous painful uterine contractions associated with the effacement and dilatation of the cervix and the descending of the presenting part. most painful experience many women encounter. pain is due to cervical and lower uterine segment dilatation, uterine contraction and distension of the structures surrounding the vagina and pelvic outlet.

4. As noted by the ASA and the ACOG There is no other circumstance where it is considered acceptable for a person to experience severe pain, amenable to safe intervention. Maternal request is a sufficient medical indication for pain relief during labor.

5. Sympathetic Stimulation PAIN Suffering Loss of Morale Anxiety  O 2 Consumption Hyperventilation Hypocarbia  Catecholamine release Impaired uterine contractions  Uteroplacental blood flow  Cardiac Output  Blood Pressure Delayed gastric emptying  Lactic Acid  Free fatty acid Maternal metabolic acidosis Fetal acidemia Fetal hypoxemia

6. Effect of pain on mother and fetus Respiratory Increase in tidal volume and minute ventilation-> hyperventilation->hypocapnia->reduces cerebral and uteroplacental circulation->maternal hypoxia and fetal hypoxia->late deceleration of FHR Cardiovascular Increase in circulatory cathecholamine esp. Norad ->decrease in uterine blood flow Increase in CO,HR,SVR Neuroendocrine system Increase in circulatory cathecholamine level, corticosteroids, ACTH->exacerbate stress response->decrease uterine blood flow Metabolic effects Hyperventilation->ODC shift to left-> respi alkalosis Increased loss og HCO3 by renal system-> metabolic acidosis Increase O2 consumption GIT Inhibition of gastrointestinal motility-> delayed gastric emptying Decrease PH and upper esophageal tone leads to reflux gastritis

7. Stages of labor First stage of labor: True uterine contraction to fully dilation of cervix 10cm. Latent phase:-cervix dilation slowly reach to 4 cm. Active phase:- rapid dilation of cervix to reach 10cm Primi:8 -12 hrs Multi:- 6-8 hrs

8. Second stage: complete cervical dilation to birth of fetus. Primi - 1 hrs Multi ½ hrs 3 rd stage: expulsion of placenta and membranes. 30 min.

9. Cervical dilatation at different Stages of Labor

10. Physiology of Pain in Labor 1 st stage of labor – mostly visceral, Dull aching and poorly localized Dilation of the cervix and distention of the lower uterine segment Pain impulses are transmitted by afferent, slow conducting, A-delta and C fibres accompanying sympathetic nerves enters spinal cord at T10 to L1 level.

11. 2 nd stage of labor mostly somatic Distention of the pelvic floor, vagina and perineum Sharp, severe and well localized Stimuli enter spinal cord at S2 to S4 through pudendal nerve.

12. Ideal labor analgesics Provides good analgesics Be safe for the mother and baby Be predictable and constant in its effects Be easy to administer No loss of maternal consciousness Should not interfere with uterine contractions or progress of labor Should not interfere with mobility.

13. VARIOUS MODALITIES AVAILABLE NON PHARMACOLOGICAL PHARMACOLOGICAL

14. APPLICATION OF NON PHARMACOLOGICAL METHODS OF LABOR ANALGESIA Useful in primary set ups Regional block facility not available Safe No side effects Primarily 1st stage analgesia However unsatisfactory in large no of patients

15. Non pharmacological methods Acts by: Psycho-prophylaxis: altering the pain perception Activating peripheral pain perception

16. Psychoprophylaxis : patterned breathing and relaxation techniques Physiologically by improving oxygenation and reducing muscle tension, Cognitively by focusing on breathing and relaxation instead of pain Psychologically by reducing fear, anxiety and improving the sense of personal control

17. Psycho-prophylaxis Lamaze technique Leboyer’s method Hypnosis Continuous labor support Yoga Relaxation and breathing Music and audioanalgesia

18. Technique that activate peripheral sensory perception Application of heat and cold Transcutaneous electrical nerve stimulation Acupunture and Acupressure Intradermal water blocks Water baths in labor Touch and massage

19. Superficial applications of heat or cold Easy to use, inexpensive Minimal negative side effects when used properly Heat application: back, lower abdomen, groin and perineum Heat sources: hot water bottle, heated rice-filled shock, warm compress (wash clothes soaked in warm water), electric heating pad, warm blanket and warm bath or shower

20. TRANS CUTANEOUS ELECTRICAL NERVE STIMULATION transmission of low voltage electric current to skin via surface electrodes Mechanism of action: Blockade of pain transmission through stimulation of A- fibres transmission (gate theory) Local release of beta endorphins Disadvantage Latency(40 min to become effective) Interferes with fetal heart monitoring Less effective in 2 nd stage of labor

21. Contd.. Electrodes placement: 1 st stage of labor : about 2cm over T10-L1 dermatome on either side of the spinous process 2 nd stage : over S2-S4 dermatome Amplitude and frequency of the current are varied as the labor progresses.

22. STERILE WATER BLOCK lower back pain during labor. Effective in 1 st stage of labor Mechanism : osmotic distension of skin by salt free water stimulates nociceptors and inhibits pain transmission from uterus and cervix (gate theory) Transiently painful for 30 s Onset of pain relief : 2 mins last till 45 to 120 mins

23. Pharmacological techniques for labor analgesia

24. Pharmacological methods Systemic analgesia: Opioids Inhalational Recently, paracetamol Regional analgesia: Central neuraxial blockade Paracervical and pudendal nerve block Lumbar sympathetic block

25. Inhalational Analgesia Sub anesthetic concentrations of inhaled anesthetics Mother remain awake with protective laryngeal reflexes Either alone or as a supplement to regional anesthesia Easy and rapid (decrease FRC, increase MV in pregnancy) No effect on progress of labor Make uterine contraction tolerable

26. Disadvantages: Incomplete pain relief and unpleasant smell Specialized vaporizers Risk of over dose and sedation Environmental pollution hazards Need maternal monitoring and scavenging Post hyperventilation hypoxia

27. Entonox (02:N2O 50:50) administered via facemask/mouth piece connected to breathing circuit with a demand valve Time from inhalation to peak analgesia effect: 50 seconds Intermittent administration 1 st stage: inhale 30 seconds before the onset of contractions 2 nd stage: 2-3 breaths before expulsive force Continuous administration: increased sedation, loss of consciousness, and airway compromise

28. Sevoflurane/ Sevox 0.8% sevoflurane with oxygen in oxford miniature vaporizer Good analgesia with minimal sedation Pleasant odor, non irritant to the respiratory tract Useful pain relief during the first stage of labor Greater analgesia than Entonox More sedation with sevoflurane

29. Systemic Analgesia Indications: Regional contraindicated or technically difficult or not available Disadvantages: Poor efficacy Maternal/neonatal effects of opioids Maternal side effects: sedation, respiratory depression, orthostatic hypotension, nausea and vomiting, gastric motility and delays emptying Fetal effects: FHR variability, resp depression, APGAR score, neurobehaviour changes

30. Parenteral Opioid Analgesia Intermittent bolus Patient-controlled opioid analgesia: Superior analgesia with smaller drug doses Lower incidence of side effects Patient control of analgesia

31. Meperidine most commonly used parenteral opioid analgesic effect lasts up to 2-3 hours cause sedation, respiratory depression in the neonate neonatal effects most likely if delivery occurs between 1 and 4 hr. after administration Babies sleepier, less attentive, less able to establish breast feeding despite normal Apgar score.

32. Tramadol Synthetic opioid IM: 100mg/10-30min (onset)/ 3-4 hrs (duration) Moderate analgesia (effective in 1 st stage) Mild respiratory depression Side effects: nausea, vomiting, sedation, dry mouth, sweating High placental permeability

33. Fentanyl Synthetic opioid Highly lipid soluble, protein bound Provides reasonable levels of analgesia with minimal neonatal depression. 25 to 50 µg intravenously peak effect occurs within 3 to 5 minutes and has a duration of 30 to 60 minutes

34. IV-PCA Fentanyl during labor Loading dose: 50-100mcg No background infusion 10-12.5mcg bolus 8-10 min lockout 4 hour limit- 300mcg Pulse oximeter when large doses

35. Remifentanil Potent, short-acting µ-opioid receptor agonist Half-life is 1.3 minutes Fetal exposure to the drug is minimized because of its rapid metabolism or redistribution Bolus dose of 0.4 µg/kg or continuous infusion of remifentanil at 0.05 µg/kg/min.

36. MORPHINE Infrequent use during labor, greater respiratory depression in neonate NSAID Ketrolac is used for postoperative analgesia. few data about administration of ketorolac during labor.

37. KETAMINE Dose: 0.25mg/kg, onset <30sec, duration: 3-5min Infusion: 0.25mg/kg followed by 0.25mg/kg/ hr Minimal maternal and fetal complications at lower doses Indications: Imminent vaginal delivery in parturient without regional anesthesia Adjunctive agent in parturient with unsatisfactory regional anesthesia

38. BARBITURATES Early stage labor managed with either IM or oral barbiturates. phenobarbitol 100 to 200 mg Effect 1hr after oral,30 min after IM. BENZODIAZEPINES not used in labor.

39. Regional Analgesia Epidural analgesia Combined spinal epidural analgesia Spinal analgesia Continuous spinal analgesia Dural puncture epidural (DPE) Paracervical block Pudendal nerve block

40. Epidural Labor Analgesia Gold standard for pain relief in labor Excellent pain relief and maternal satisfaction Minimal fetal side effects and maternal adverse effects Easily converts to surgical anesthetic, even in emergent/urgent situation

41. PRE-REQUISITES Pre anesthetic check up Consent IV access and monitor Facility of resuscitation equipment and drugs, oxygen, suction, intubation equipment, IPPV

42. Epidural analgesia: mode of administration Intermittent top ups Continuous infusion Patient controlled epidural analgesia: With basal infusion Without basal infusion Computer integrated PCEA

43. ELA Administration techniques INTERMITTENT TOP UP CONTINOUS INFUSION PCEA -Simple method of delivery -no need for complex infusion devices -interrupted pain -spread and quality of analgesia may change with repeated epidural inj. -continuous level of comfort -less sacral sparing -greater cardiovascular stability -catheter migration -Motor block increases with prolonged infusion -patient satisfaction is better -incidence of motor blockade is less -local anesthetic consumption is reduced -requires dedicated infusion pump and proper patient education.

44. Test dose Test dose for epidural labor analgesia 45mg lignocaine + 15mcg epinephrine given in uterine diastole Intravascular injection: Sudden, fast acceleration in maternal heart rate of at least 15-20 bpm, SBP by 15-25 mm Hg occurring within 1 min and duration 60 secs Intrathecal injection: Onset of motor blockade within 3-5 min

45. Disadvantages: A high incidence of false positives (intravascular) Possible adverse effects on uterine blood flow and fetal well-being Causes exaggerated response in hypertensive patients Intrathecal- greater motor and sensory block, undesirable Recent: No test dose but careful aspiration before each top up Incremental dosage

46. Epidural regimen for labor analgesia Low dose regimens: combination of a local anesthetic with an opioid Reduced the total dose of local anesthetic Less motor blockade Effective analgesia Drugs: Ropivacaine 0.1-0.2% Bupivacaine 0.125-0.0625% In combination with 0.002% fentanyl/ sufentanyl

47. Subsequent analgesia options A. intermittent: 8-10ml bolus, repeat initial bolus as necessary to maintain maternal comfort B. continuous infusion: 8-12ml/ hr : 1. Bupivacaine 0.0625-0.125% + fentanyl 1-2mcg/ml 2. Bupivacaine 0.125% without opioid 3. Ropivacaine 0.5-2.0% C. PCEA: Bupivacaine 0.05-0.125% + Fentanyl 2mcg/ml 5 ml bolus Background infusion 3-6ml/ hr Hourly limit 30ml Lockout interval 5-15 mins

48. Programmed intermittent epidural bolus or automated mandatory epidural boluses relatively new innovative protocol. Drug delivery pump delivers preset volume of epidural mixture as bolus at timed interval. total local anesthetic solution is administered as intermittent boluses of LDMs (e.g., two 5 mL boluses within 30 min instead of a 10 mL/h epidural infusion). provides similar analgesia, higher maternal satisfaction, less unscheduled rescue boluses. Anesthesia provider manipulates infusion solution, patient-controlled bolus volume, lockout interval, background infusion rate, and maximum allowable dose per hour.

49. Computer integrated patient-controlled epidural analgesia preset algorithm to analyze LA dose changes basal infusion rate based on previous hour demand requirement for patient-administered bolus doses. basal infusion is adjusted to 5, 10, or 15 mL/h if the parturient required one, two, or three demand boluses, respectively and decreases by increments of 5 mL/h if there were no bolus demands significant reduction in breakthrough pain without increasing local anaesthetic consumption or side effects.

50. Monitoring Measure BP every 1-2 min for first 10 min, then every 5-15 min during the infusion and until the block wears off. Monitoring: partogram - uterine contractions, FHR, cervical dilatation, i /v fluids, urinary output Patient should turn from side to side every 30 mins to avoid one sided block Check regularly for sensory level, adequacy of analgesia and motor block

51. Single Shot Spinal Analgesia Can provide immediate pain relief for immediate delivery. Suitable in very early labor to enable epidural placement under more controlled conditions Multiparous- suitable candidate due to rapid labor progression For instrumental deliveries in women who do not have an indwelling epidural catheter Opioid alone or low dose LA + opioid AGENTS DOSE DURATION Fentanyl 15-25mcg 85-95 min Sufentanyl 5-10mcg 105-115 min Bupivacaine 2.5mg 60 min

52. Combined Spinal Epidural Analgesia Effective, rapid-onset analgesia with ability to prolong the duration of analgesia Technique: individual single-shot spinal followed by placement of an epidural catheter technique or needle-through-needle technique Decrease incidence of sacral sparing Minimal motor block so ambulation possible- walking epidural

53. Advantages of CSEA Compared with epidural anesthesia Lower maternal, fetal, and neonatal plasma concentrations of anesthetic agents More rapid onset of analgesia and anesthesia Denser sensory blockade Complete early labor analgesia with opioid alone (no local anesthetic necessary) Lower failure rate

54. Compared With Spinal Anesthesia Technically easier in obese individuals. Ability to titrate anesthetic dose, Results in less hypotension Ability to extend the extent of neuroblockade . Continuous technique: ability to extend duration of anesthesia

55. Walking Epidural Also called ambulatory epidural. Also called minimal motor block epidural Low dose CSE opioid analgesia because motor function maintained and the ability to walk not impaired. Any neuroaxial analgesia technique allowing safe ambulation Methods: CSE: Queen Charlotte regimen Intrathecal-12.5 to 25mcg of fentanyl + 2.5 mg of 0.5% bupivacaine Epidural- 0.0625% bupivacaine + 2mcg/ml fentanyl {10ml}

56. Advantages: Adopting upright position may increase the pelvic diameter. Decreased aorto caval compression Improves uterine contractions May encourage correct positioning of fetal head.

57. Criteria for Ambulation during labor with Neuroaxial Analgesia Reassuring fetal status Engagement of fetal presenting part Stable orthostatic vital signs(asymptomatic and within 10% of baseline) Ability to perform bilateral straight-leg raises in bed against resistance Ability to step on step stool with either leg without assistance Satisfactory trial of walking accompanied by a nurse Patient must be accompanied by a companion at all times. Intermittent fetal heart rate monitoring: every 15 mins

58. Dural Puncture Epidural (DPE) Modification of CSE Dural perforation is created from a spinal needle but intrathecal medication administration is withheld

59. Compared with epidural(EPL) and CSE technique DPE technique has the advantages of: Earlier onset Increased likelihood of functional epidural catheter due to confirmation of midline on placement. Lesser top ups Improves caudal spread of analgesia Less side effects like pruritus, hypotension etc .

60. Side effects of Neuroaxial Analgesia Hypotension Pruritus Nausea and vomiting Fever Shivering Urinary retension Recrudescence of HSV Delayed gastric emptying

61. Complications of Neuraxial Analgesia Inadequate analgesia Unintentional dural puncture Respiratory depression Intravascular injection of LA High and total spinal anesthesia Extensive motor blockade Prolonged blockade Sensory changes Back pain Pelvic floor injury.