capt azz labour analgesia.pptx 2024 mmedsc

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1. LABOUR ANALGESIA Capt Aung Zaw Zaw PG II (O&G)

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

3. Introduction Labour 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. 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

5. Stages of labour First stage of labour : 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

6. 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.

7. Physiology of Pain in Labour 1 st stage of labour – 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.

8. 2 nd stage of labour 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.

9. Ideal labour 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 labour Should not interfere with mobility.

10. VARIOUS MODALITIES AVAILABLE NON PHARMACOLOGICAL PHARMACOLOGICAL

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

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

13. 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

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

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

16. 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

17. 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

18. 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.

19. 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

20. Pharmacological techniques for labour analgesia

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

22. 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 No effect on progress of labour Make uterine contraction tolerable

23. 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

24. 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

25. 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

26. 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

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

28. 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.

29. 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

30. 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

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

32. 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.

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

34. 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

35. 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 labour .

36. Regional Analgesia Epidural analgesia Combined spinal epidural analgesia Spinal analgesia Continuous spinal analgesia Paracervical block Pudendal nerve block

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

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

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

40. 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

41. 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

42. Epidural regimen for labour 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

43. 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

44. 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

45. 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

46. 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

47. 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}

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

49. Criteria for Ambulation during labour with Neuroaxial Analgesia Reassuring fetal status Engagement of fetal presenting part Stable orthostatic vital signs(asymptomatic and within 10% of baseline) 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

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

51. 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