obstetrical analgesia anesthesia 5th year medical student dr. wafaa sait

1. Obstetrical Analgesia & Anesthesia

3. -The normal physiological changes during pregnancy, superimposed by disorders unique to pregnancy, such as ( PIH, APH, Chorioamnionitis�..etc) - Presence of the infant - The effect of analgesic on labor - Duration of labor and delivery

4. Maternal Mortality Rate ; have been decreased from 4.3 ? to 1.7 per million live birth The most important single factor associated with anesthesia related - maternal mortality is the experience of the anesthetist.

5. Causes of Anesthesia � related Maternal Death in U.S from 1979-1990: General Anesthesia Vs Regional Analgesia Complication Aspiration Intubation problem Inadequate ventilation Respiratory failure Cardiac arrest Toxicity High spinal / epidural Unknown Adapted from Hawkins and colleagues ( 1997 ) , with permission. General Regional Anesthesia Anesthesia 33 % _ 22 % _ 15 % _ 3 % _ 22 % 6 % _ 51 % _ 36 % 5 % 6 %

6. Risk Factors : Marked obesity Severe edema or anatomical anomalies of the face and neck Protuberant teeth , small mandible or difficulty in opening the mouth

7. � Short stature, short neck, or arthritis of the neck Large Thyroid Asthma , chronic pulmonary disease , or cardiac disease

8. Bleeding disorders Severe pre-eclampsia � eclampsia Previous history of anesthetic complication Other significant medical or obstetrical complications

9. Essential of Obstetrical pain relief Simplicity Safety Preservation of fetal homeostasis

10. Analgesia and Sedation during labor Narcotic and Tranquilizer ; ( Meperidine and Promethazine ) � Dose: 50 _100 mg + 25 mg Promethazine , every 2 _4 hrs � Analgesia is maximal about 45 min of IM injection and almost immediately after IV injection � The depressant effect in the fetus follows closely behind the peak analgesic effect in the mother � Meperdine cross the placenta � Half life approximately 2 � hrs in the mother and 13 hrs in the new born

11. Other Narcotics : Butorphanol : Synthetic Narcotic 1 � 2 mg Nalbuphine : Synthetic Narcotic 15 � 20 mg Fentanyl : Short acting very potent synthetic Opioid 50 � 100 mg IV / hr

12. Narcotic Antagonist; Naloxan Hydrochloride (Narcan) � New born respiratory depression is most likely to occur 2-3 hrs after Meperidine administration � � Naloxan displacing the Narcotics from specific receptors in the central nervous system � Dose : 0.1 mg / Kg in the umbilical vein � Acts within 2 min with an effective duration of at least 30 min � It has to be repeated in 3 � 5 min

13. GENERAL ANESTHESIAA ) Inhalation Anesthesia Gas Anesthetics : Nitrous Oxide (N2O) Self � administered nitrous oxide in a 50 % mixture with 50 % oxygen (Nitronox), provide excellent pain relief during labor & second stage of labor , It is also used as part of balanced general anesthesia Volatile Anesthetics : Isoflurane & Halothane Are potent non-explosive Halogenated hydrocarbon agents that produce remarkable uterine relaxation when given in high inhaled concentration They are used to supplement N2O during maintenance of Gen.Anes.

14. Indications for use in high concentration : � Internal podalic version of the second twin � Breech decomposition � Replacement of the acutely inverted uterus

15. Side effect : � Fetal narcosis Cardio-depressant Hypotension Hepatitis & massive hepatic necrosis Increased blood loss

16. General AnesthesiaB) Intravenous anesthesia Thiopental (Thiobarbituate) It is given along with muscle relaxant and N2O to produce general anesthesia Advantage : It is easily and rabidly induce anesthesia with prompt recovery and minimal risk of vomiting Ketamine In a small dose of 0.2 - 0.3 mg / kg is used to produce analgesia and sedation just prior to delivery In a dose of 1 mg / kg it induce general anesthesia It causes rise in blood pressure , for that it may be useful in patient with acute hemorrhage

17. Hazard of General Anesthesia ? Fetal central nervous system depression ? Aspiration of gastric content and particulate matter ? Failed tracheal intubation

18. Aspiration during general anesthesia ( pneumonitis from inhalation of gastric contents ) � Mendelson Syndrome� Prophylaxis: Fasting for at least 8 hours Use of agents to reduce gastric acidity Skillful tracheal intubation � Cricoids pressure � Passage of nasogastric tube to empty the stomach content Awake intubation Use of regional analgesia when appropriate

19. Failed intubation: Is uncommon , It is the major cause of anesthesia related maternal mortality Prevention: History , careful assessment and examination and appropriate pre-operative preparation for immediate management by : - Short handled laryngoscope - Fiber-optic laryngoscope - A wake intubation

20. Sensory Innervations of the genital tract Uterine Innervations : Visceral sensory fibers from uterus, cervix, &upper vagina traverse through: Frakenhauser ganglion ? Pelvic Plexus ? Meddle & Superior internal Iliac Plexus ? Sympathetic chain 10th, 11th ,12th And first lumbar Motor Pathways : 7th ,8th thoracic Lower genital tract innervations : Pudendal nerve (2nd, 3rd, & 4th sacral nerve) Provide sensory inervations to Perineum, Anus, and the more medial and inferior parts of the vulva & introitus

21. Some local Anesthetic agents used in obstetricConcentration Volume Dose Duration Anesthetic Agents ( % ) ( ml ) ( mg ) Onset Clinical use Amino � esters 2-Chloroprocaine 1 � 2 20-30 400-600 Rapid 15-30 Local or pudendal 2 � 3 15-25 300-750 30-60 Epidural for cesarean Tetracaine 0.2 _ 4 slow 75-150 Low spinal block 0.5 _ 7 � 10 75-150 Spinal for cesarean Amino � amide Lidocaine 1 20-30 200-300 Rapid 30-60 Local or pudendal 2 15-30 300-450 60-90 Epidural for C/S 5 1-1.5 50-75 45-60 Spinal for C/S or puerperal tubal liga 5 0.5-1 25-50 30-60 Spinal for vaginal delivery Bupivacaine 0.5 15-20 75-100 Slow 90-150 Epidural for cesrean 0.25 8-10 20-25 60-90 Epidural for labor 0.75 1-1.5 7.5-11 60-120 Spinal for C/S Ropivacaine 0.5 15-20 75-100 Slow 90-150 Epidural for cesarian 0.25 8-10 20-25 60-90 Epidural for labor

22. Toxicity:{ injection of the anesthetic agents in to a blood vessel, or by administration of excessive amount } Symptoms of Central nervous system Toxicity Light � Headedness , Dizziness , Slurred speech , Tinnitus , Bizarre behavior , Metallic taste . Numbness of the tongue & mouth, Muscle fasciculation & excitation , Generalized convulsion & loss of cosciousness . Management: establish air way, Oxygen ,Succinylcholine Thiopental ,or Diazepam , MgSO4 Cardiovascular Toxicity : Hypertension & tachycardia soon followed by Hypotension & cardiac arrhythmias Management: Turn patient to her side Crystalloid infusion I.V ephedrine

23. Regional Analgesia cont� A ) Local Infiltration: � Before episiotomy and delivery � After delivery into the site of lacerations to be repaired � Around the episiotomy wound B ) Pudendal block: � Relief pain of the lower vagina & posterior vulva � It is a safe , simple method for spontaneous delivery and outlet forceps only Complications: Systemic toxicity , Haematoma formation Infection (rare)

24. C ) Para cervical Block: � Lidocaine or Chloroprocaine 5-10 ml � Injected at 3 & 9 O�clock position � Provide excellent pain relief during 1st stage of labor Complications: Fetal bradycardia: ( the effect may be the consequence of Transplacental transfer of the anesthetic agent or its metabolites )

25. D ) Spinal ( subarachnoid ) block � Subarachnoid space is smaller in pregnancy , most likely due to the engorgement of the internal vertebral venous plexus � � All anesthetic agent can be used � Low spinal block , � 10th thoracic dermatome � for vaginal delivery and instrumental delivery � up to the 8th thoracic dermatome � for cesarean delivery

26. Complication 1) Hypotension: � Is the consequence of vasodilatation from sympathetic blockade � Obstructed venous return from uterine compression of the vena cava Treatment: Uterine displacement Hydration with 500-1000 ml of a balanced salt solution Ephedrine 5-10 mg Iv if hypotension persist 2 ) Total spinal blockade: � as a result of excessive dose of analgesic agent � Patient will develop, hypotension, apnea, cardiac arrest

27. 3) Spinal ( post puncture ) Headache: � due to leakage of cerebrospinal fluid from the site of puncture of the meninges � Prophylactic measures: Use a small � gauge spinal needle Avoiding multiple punctures Treatment: Hydration , abdominal support with a binder , blood patch 4) Convulsions: Rare instance , presumably caused by cerebrospinal fluid hypotension

28. 5) Bladder dysfunction: 6) Oxytocics and hypertension: 7) Arachnoiditis and meningitis: � rare complication , the local anesthetic agents are no longer preserved in alcohol , formalin or toxic solute , and disposable equipment are used most of the time"

29. Contra indication to spinal analgesia ? Obstetrical complications that are associated with maternal hypovolemia and hypotension ? Disorders of coagulation and defective homeostasis ? Infection at the site of puncture ? Neurological disorders ? Significant aortic stenosis & pulmonary hypertension

30. E ) Epidural Analgesia � The epidural space is a potential space that contains areolar tissue , fat , lymphatic and the internal venous plexus , which becomes engorged during pregnancy � Portal of entry: - lumbar intervertebral space for lumbar epidural analgesia - Sacral hiatus & sacral canal for caudal epidural analgesia The block should be from : - the level 10th thoracic to the 5th sacral for the pain of L/D - the level of 8th thoracic to the 1st sacral for cesarean

31. Complications of epidural Analgesia Immediate: Total spinal blockade Hypotension Urinary retention Headache Central nervous stimulation ( seizures ) Meningitis Cardio-respiratory arrest Vestibulocochlear dysfunction Long term complication: Back ache , Neck ache ,Tingling in hands or fingers , frequent headach

32. Effect on labor:� Prolongs first stage of labor Increases the need for labor stimulation with oxytocin Increases the chance of instrumental delivery Increase the rate of severe perineal trauma

33. Contra indication: As for spinal analgesia include : - Actual or anticipated hemorrhage - Infection at or near the site of puncture - suspicion of neurological disease

34. Discuss method of pain relief during labor and delivery ?