Pain relief in labor 4th year 2022-2023 - PowerPoint Presentation

1. Pain relief in labor4th year 2022-2023ا.د.اسراء حميد المعيني

2. Principles of Pain ReliefLabor pain caused by uterine contractions and cervical dilation is transmitted through visceral afferent sympathetic nerves entering the spinal cord from T10 through L1 Later, perineal stretching transmits painful stimuli through the pudendal nerve and sacral nerves from S2 through S4 Cortical responses to pain and anxiety are complex and may be influenced by multiple factors.

3. Non-pharmacological methods-Relaxation and breathing exercises may help the woman to manage her pain. Prolonged hyperventilation can make the woman dizzy and can cause alkalosis.- Relaxation in warm water during the first stage of labour . -Acupuncture and hypnosis are sometimes employed.-Transcutaneous electrical nerve stimulation (TENS) works on the principle of blocking pain fibres in the posterior ganglia of the spinal cord by stimulation of small afferent fibres.

4. Pharmacological methods:A-Opiates: such as pethidine and diamorphine They provide only limited pain relief during labour and furthermore may have significant side-effects. Diamorphine may be slightly more effective and may have less effect on the neonate than pethidine and is slowly replacing pethidine

5. Side-effects of opioid analgesia 1-Nausea and vomiting (they should always been given with an antiemetic )2-Maternal drowsiness and sedation.3-Delayed gastric emptying (increasing the risks of general anaesthesia).4-Short-term respiratory depression of the baby.Naloxone is a narcotic antagonist capable of reversing respiratory depression induced by opioid narcotics. 5-Possible interference with breastfeeding.

6. Roots of administration:Opiates tend to be given as intramuscular injections; however, an alternative is a subcutaneous or intravenous infusion by a patient-controlled analgesic device (PCA). This allows the woman, by pressing a dispenser button, to determine the level of analgesia that she requires. If a very short-acting opiate is used, the opiate doses can be timed with the contractions.

7. B-Inhalational analgesiaNitrous oxide (NO) in the form of Entonox® (an equal mixture of NO and oxygen) It has a quick onset, a short duration of effect and is more effective than pethidine. It may cause light-headedness and nausea. It is not suitable for prolonged use from early labour because hyperventilation may result in hypocapnoea, dizziness and, rarely, tetany and fetal hypoxia. It is most suitable later on in labour or while awaiting epidural analgesia.

8. C-NERVE BLOCKSThese include pudendal, paracervical, and neuraxial blocks such as spinal, epidural and combined spinal-epidural techniques.Anesthetic Agents for nerve block: Commonly used nerve block anesthetics are lidocaine, bupivacaineThe dose of each agent varies widely and is dependent on the particular nerve block and physical status of the woman. The onset, duration, and quality of analgesia can be enhanced by increasing the anesthetic agent’s dose, concentration, and volume or by altering its delivery mode.

9. 1-Pudendal Block The pudendal nerve passes beneath the posterior surface of the sacrospinous ligament just as the ligament attaches to the ischial spine.The pudendal nerve block is a relatively safe, simple method of analgesia for vaginal delivery ,but usually does not provide adequate analgesia when delivery requires extensive obstetrical manipulation( complete visualization of the cervix and upper vagina or manual exploration of the uterine cavity is indicated)

10. A tubular introducer with needle introduce into position near the pudendal nerve ,just beneath the tip of the ischial spine. The needle is pushed beyond the introducer tip into the mucosa, 1 mL of 1% lidocaine solution . First aspiration ,then the needle is then advanced until it touches the sacrospinous ligament, which is infiltrated with 3 mL of lidocaine. The procedure is repeated on the other side Within 3 to 4 minutes of injection, the successful pudendal block will allow pinching of the lower vagina and posterior vulva without pain. If delivery occurs before the pudendal block becomes effective and an episiotomy is indicated, infiltrated with 5 to 10 mL of 1% lidocaine solution directly . The pudendal block usually has become effective by the time of repair.

11. Complications :1-intravascular injection of a local anesthetic agent may cause serious systemic toxicity.2- Hematoma formation from perforation of a blood vessel is most likely when there is a coagulopathy . 3-Pudedal neuralgia: 4-Rarely, severe infection may originate at the injection site. The infection may spread posteriorly to the hip joint, into the gluteal musculature, or into the retropsoas space .

12. 2- Paracervical BlockThe cervix, vagina, and uterus are richly supplied by nerves of the uterovaginal plexus . This plexus lies within the connective tissue lateral to the uterosacral ligaments. Thus, injections are most effective if placed immediately lateral to the insertion of the uterosacral ligaments into the uterus . For paracervical blockade, usually 1% lidocaine or 3% chloroprocaine, 5 to 10 mL, is injected into the cervix laterally at 4 and 8 o’clock positions.Limitations; This block usually provides satisfactory pain relief during first-stage labor, additional analgesia is required for delivery.The block may have to be repeated during labor because these anesthetics are relatively short acting. Fetal bradycardia is a worrisome complication . Thus, paracervical block should not be used in situations of potential fetal compromise

13. D-Neuraxial Regional Blocks1-Epidural analgesiaEpidural (extradural) analgesia is the most reliable means of providing effective analgesia in labour. The woman that she may lose sensation and movement in her legs temporarilyAn epidural will limit mobility and for this reason, it is not ideal for women in early labour. However, women in severe pain, can be used even in the latent phase of labour, OR advanced cervical dilatation.More intensive level of maternal and fetal monitoring will be necessary, like continuous EFM (the CTG). The epidural analgesia does not increase caesarean section rates. The second stage is longer and there is a greater chance of instrumental delivery, which may be lessened by a longer passive second stage awaiting a maternal urge to push.In certain clinical situations, an epidural in the second stage of labour may assist a vaginal delivery by relaxing the woman and allowing time for the head to descend and rotate.

14. Indications for regional analgesia for labour.1-Pain relief: Avoid the deleterious effects of pain (maternal exhaustion, raised catecholamines, maternal and fetal acidosis)2-Reduce premature urge to push3-Anaesthesia for manual removal of placenta4-Reduce need for emergency general anaesthesia5-Multiple pregnancy (rapid anaesthesia for delivery of after‐coming twin if required)6-Breech7-Suspected cephalopelvic disproportion/macrosomia8-? Previous caesarean section9-? Obesity

15. 10- Improve maternal condition Reduces oxygen demand, (especially women with cardiac/ respiratory disease) Reduces circulating catecholamines (especially maternal fixed cardiac output states) 11-Improve uteroplacental flow/fetal condition :pre‐eclampsia, Preterm labour, Impaired uteroplacental function (poor Doppler/non reassuring CTG) 12-Decreases urge to push in second stage

16. Contraindications1-Coagulation disorders (e.g. low platelet count).2-Local or systemic sepsis.3-Hypovolaemia.4-Logistical: insufficient numbers of trained staff (anaesthetic and midwifery).

17. Complications of epidural analgesia1-Accidental dural puncture during the search for the epidural space 1% of cases. If the subarachnoid space is accidentally reached with an epidural needle, this may allow leakage of cerebrospinal fluid (CSF) and results in a ‘spinal headache’. This is characteristically experienced on the top of the head and is relieved by lying flat and exacerbated by sitting upright. 2-Accidental total spinal anaesthesia (injection of epidural doses of local anaesthetic into the subarachnoid space) causes severe hypotension, respiratory failure, unconsciousness and death if not recognized and treated immediately. The mother requires intubation, ventilation and circulatory support. Hypotension must be treated with intravenous fluids, vasopressors and positioning of the woman onto her left side. In some cases, urgent delivery of the baby may be required to overcome aorto-caval compression and so permit maternal resuscitation.

18. 3-Bladder dysfunction can occur if the bladder is allowed to overfill because the woman is unaware of the need to micturate, particularly after the birth while the spinal or epidural is wearing off.To avoid this, catheterization of the bladder should be carried out during labour .4-Hypotension can occur with epidural analgesia, although it is more common with spinal anaesthesia. It can usually be rectified with fluid boluses, but may need vasopressors. Occasionally, maternal hypotension will lead to fetal compromise

19. 5- Spinal haematomata and neurological complications are rare, and are usually associated with other factors such as bleeding disorders. 6- Drug toxicity can occur with accidental placement of a catheter within a blood vessel. This is normally noticed by aspiration prior to injection.7-Short-term respiratory depression of the baby is possible because all modern epidural solutions contain opioids, which reach the maternal circulation and may cross the placenta.

20. TechniqueAseptic technique is used,The woman’s back is cleansed and local anaesthetic is used to infiltrate the skin. The woman may be in an extreme left lateral position, or sitting upright but leaning over. Flexion at the upper spine and at the hips helps to open up the spaces between the vertebral bodies of the lumbar spine. The epidural catheter is normally inserted at the L2–L3, L3–L4 or L4–L5 interspace and should come to lie in the epidural space, which contains blood vessels, nerve roots and fat The catheter is aspirated to check for position and, if no blood or CSF is obtained,

21. a ‘test dose’ is given to confirm the catheter position This test dose is a small volume of dilute local anaesthetic that would not be expected to have any clinical effect. If indeed it has no obvious effect on sensation in the lower limbs, the catheter is correctly sited. If, however, there is a sensory block, leg weakness and peripheral vasodilatation, the catheter has been inserted too far and into the subarachnoid (spinal) space. Inserting the normal dose of local anaesthetic into the spinal space by accident would risk complete motor and respiratory paralysis. If none of these signs is observed 5 minutes after injection of the test dose, a loading dose can be administered. The epidural solution is usually a mixture of low-concentration local anaesthetic (0.1% bupivacaine) with an opioid such as fentanyl.

22. After the loading dose is given, the mother should be kept in the right or left lateral position Her blood pressure should be measured every 5 minutes for 15 minutes. A fall in blood pressure may result from the vasodilatation caused by blocking of the sympathetic tone to peripheral blood vessels. This hypotension is usually short lived, but may cause a fetal bradycardia due to redirection of maternal blood away from the uterus. The mother should never lie supine, as aorto-caval compression can reduce maternal cardiac output and so compromise placental perfusion.

23. Hourly assessment of the level of the sensory block using a cold spray is critical in the detection of a block that is creeping too high and risking respiratory compromise. Regional analgesia can be maintained throughout labour with either intermittent boluses or continuous infusions. Patient controlled epidural analgesia is an option. Women should be encouraged to move around and adopt whichever upright position suits them best. Full mobility is unlikely. Reducing the rate of an epidural infusion in the second stage may increase the maternal awareness to push, but care should be taken that the analgesic effect is not compromised. Regional anaesthesia should be continued until after completion of the third stage of labour, including repair of any perineal injury.

24. Spinal anaesthesiaA spinal block is considered more effective than that obtained by an epidural(Labour), and is of faster onset. Spinals are not used for routine analgesia in labour. A fine-gauge atraumatic spinal needle is passed through the epidural space, through the dura and into the subarachnoid space, which contains the CSF. A small volume of local anaesthetic is injected, after which the spinal needle is withdrawn. This may be used :1-Anaesthesia for caesarean sections, 2-Trial of instrumental deliveries (in theatre) 3-Manual removal of retained placenta and4-The repair of difficult perineal and vaginal tears.

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26. Absolute Contraindications to Spinal Analgesia

27. Combined spinal–epidural (CSE) analgesia This technique has the advantage of producing a rapid onset of pain relief The provision of prolonged analgesia. Because the initiating spinal dose is relatively low.

28. Transversus Abdominis Plane Block(TAP)It is usually performed under ultrasound guidance and involves injection of a local anesthetic into the transversus abdominis plane (TAP) between the internal oblique and transversus abdominis muscles . The nerves lying in this plane supply the anterior abdominal wall at the T6 to L1 dermatomes.Local infiltration or TAP blocks can be used also for postoperative pain control.

29. GENERAL ANESTHESIAIt is often used for emergent cesarean delivery for acute fetal distress Patient PreparationBefore anesthesia induction, several steps should be taken to help minimize complication risks. 1-First, antacid administration shortly before anesthesia induction has probably decreased mortality rates from general anesthesia e.g H2-receptor antagonist,or metoclopramide.2- Lateral uterine displacement also is provided as the uterus may compress the inferior vena cava and aorta when the mother is supine.3-This preoxygenation is accomplished by administering 100-percent oxygen via face mask for 2 to 3 minutes before anesthesia induction.4- Fasting: That modest amounts of clear liquids be allowed in uncomplicated laboring women. A fasting period of 6 to 8 hours, depending on the type of food ingested, is recommended for uncomplicated parturient undergoing elective cesarean delivery . Aspiration to minimize this risk, antacids should be given routinely, intubation should be accompanied by cricoid pressure, and regional analgesia should be employed when possible.

30. Anesthetist high risk patient• Marked obesity• Severe edema or anatomical abnormalities of the face, neck, or spine, including trauma or surgery• Abnormal dentition, small mandible, or difficulty opening the mouth• Extremely short stature, short neck, or arthritis of the neck• Goiter• Serious maternal medical problems, such as cardiac, pulmonary, or neurological disease• Bleeding disorders• Severe preeclampsia• Previous history of anesthetic complications• Obstetrical complications likely to lead to operative delivery—examples include placenta previa or higher-order multifetal gestation.

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