Obstetric analgesia and anesthesia Dr Hiba Ahmed Suhail M.B. Ch. B./F.I.B.O.G. College of medicine University of Mosul

The major objectives of obstetric analgesia and anesthesia include: 1- Pain control during labour and delivery that is safe for mother and fetus 2- Anesthetic management during cesarean delivery that does not harm the mother or the neonate. 3- Assisting the obstetrician with blood pressure and heart rate of complicated pregnancy and with the management of comorbidities during labour.

Labor pain in the first stage Uterine contractions leading to : myometrial ischemia. The pain felt through hypogastric plexuses , pre aortic plexuses to spinal cord through (T10-L1). Cervical dilatation and stretching Sensation pass through nerve entering to sacral root. At this stage this pain is visceral pain, diffuse, poorly localized , in lower abdomen radiated to the back.

Labor pain in the second stage Uterine contractions Pressure on the pelvic floor structures . Stretching of the perineum The last two felt through pudendal nerve (S2, 3, 4) . This pain is somatic pain so its well localized.

Pain control Analgesia non pharmacological pharmacological parenteral inhalational Anesthesia General anesthesia Regional anesthesia spinal epidural Regional block Pudendal Para cervical

Analgesia: Analgesia refer to pain relief not involve the removal of complete sensation it is include: 1-non pharmacological Effective in relieving mild pain Massage. Homeopathy. Acupuncture. Hypnosis. Emotional support. Transcutaneous electrical nerve stimulation TENS work by block pain fibres in posterior ganglia of the spinal cord by stimulating small afferent fibres the ( gate theory ) it does not reduce pain score.

2- Pharmacological analgesia Ideal analgesia should be:- Easily administered. Rapid onset of action. Provide good analgesia. No or low side effect on both mother and fetus. No effect on the process of labour ( not affect uterine contraction or pelvic floor tone) Parenteral ( Opiates)

Fentanyl More potent synthetic analgesia . Easily administered ( parenteral ). Rapid onset. Short duration of action Cross placenta and cause neonatal complications. Side effect GIT ( nausea , vomiting , delay gastric emptying and constipation ),CNS ( confusion ) and respiratory depression.

Inhalational analgesia Nitrous oxide NO mixed with oxygen Entonox has: Quick onset. Short duration of effect. More effective than pethidine. It used for short duration latter on in labour or while awaiting for epidural analgesia. Side effect include nausea light headache and not suitable for prolonged use. Excreted through the lung.

Epidural (extradural) analgesia and anesthesia Play important role in obstetrics. The decision to have it should be combined between woman obstetric team and anesthetist. Is injected into the epidural space between L2 - L3 or L3-L4. It necessitates a block from the T10 to the S5 dermatomes A test dose is given to confirm the catheter position, if no unwanted signs is observed after 5 min of injection, a loading dose can be administered.

The main indications 1) Effective pain relief. 2) Prolonged labour. 3) Hypertension. 4) Multiple pregnancy. 5) Certain medical disease (cardiac disease). 6) High risk of operative delivery

The main contraindication: 1) Coagulation disorder. 2) Local or systemic sepsis. 3) Hypovolaemia. 4) Insufficient numbers of trained staff. 5) Patient refusal.

Complications: Maternal Complications: 1) Accidental dural puncture causing post dural headache due to leakage of CSF mainly in the top of the head and relieved by lying flat treated by injection of autologous blood patch in the epidural space. 2) Accidental total spinal anesthesia injection of local anesthetic drug in subarachnoid space. 3) Hypotension treated by IV bolus isotonic solution vasopressor phenylephrine. 4) Respiratory failure.

5) Loss of consciousness. 6) Death intubation ventilation circulatory support delivery. 7) Spinal haematoma. 8) Drug toxicity (injection in to blood vessels). 9) Bladder dysfunction over distension catheterization. 10) Hypotension un common here but more in spinal anesthesia . 11) Cardiac arrest.

Fetal complications 1) Fetal compromised if maternal hypotension developed. 2) Short term respiratory depression of the baby because of using opiates in epidural solution which is a mixture of low dose local anesthesia bupivacaine and opiates fentanyl.

Anesthesia Anesthesia refer to rendering the patient completely insensate to pain it is either general or local Combined spinal epidural analgesia has the advantage of producing rapid onset and provision of prolonged analgesia.

1) Regional anesthesia involve administration of local anesthetic to render specific part of body insensate In obstetrics it consist of spinal and epidural.

Spinal anesthesia: Drug here small volume of local anesthesia inject into subarachnoid space. It considered more effective. Faster onset. Indications anesthesia for : Caesarean section. Trial of instrumental delivery in theatre. Manual removal of placenta. Repair of difficult vaginal or perineal tear. Used when GA are contraindicated It is not used for analgesia in labour.

Complication for spinal anesthesia: 1- Headache. 2- Convulsion (rare). 3- Blindness (rare). 4- Hypotension. 5- Bradycardia. 6- Injury to spinal cord. 7- Hematoma. 8- Infection. 9- Retention of urine 10- Fair of technique.

Contraindication : Hypovolemia. Clotting disorders. Septicemia. Aanatomical deformities. Neurological disease. Patient refusal.

Epidural Anesthesia In cesarian delivery, a block extending from the T4 to the S1.

2) General anesthesia given IV or inhalation to render patient unconscious and all body insensate. Indications of GA. Emergency CS When regional anesthesia is contraindicated. Mother prefers. A prolonged surgery. No available staff for regional anesthesia. Risks of GA. Aspiration of gastric content. Neonatal depression.

Regional blocks: Para cervical block the innervation of the uterus and cervix injection of LA submucosally in to the fornix of vagina laterally to cervix It effect only first stage of labour D and C analgesia It can cause fetal bradycardia. Pudendal block Somatic pain of second stage of labour transmitted via pudendal n., it involve injection of local anesthetic below the ischial spines ( the approximate location of the pudendal nerve ). This block is administered in: Second stage of labor. Operative delivery. Suturing of perineum following delivery.

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