[HD 201] E03-T03-OB Analgesia and Anesthesia_compressed

History of Obstetric Anesthesia

• In early civilization, Genesis 3:16 KJV stated women would bring forth children in sorrow while being ruled by their husbands
• Women were banned from obtaining any form of labor analgesia
• Midwives providing labor analgesia faced execution
• The church and state merged in the 1800s
• Queen Victoria requested labor analgesia for her 8th child
• John Snow administered chloroform
• The procedure was named Chloroform "a la Reine", which roughly means "in the queen's style"
• This was considered the birth of labor analgesia
• A country's civilization is gauged by how women are treated
• The right to suffrage and labor analgesia options were granted
• Labor analgesia should be a standard of care

Labor Pain Pathway

• Pain is an unpleasant sensory and emotional experience tied to actual or potential tissue damage
• Pain intensity is measured on a scale from 0 (no pain) to 10 (most pain imaginable)
• Pain character can be sharp, dull, burning, or aching
• Nociceptors fire, signaling the spinal cord and brain, creating pain perception
• Uterine contractions act as noxious stimuli, processed in the CNS
• Labor pain is likely among the most painful experiences for women
• Options include spinal or epidural techniques

Pain in Stages of Labor First Stage

• Duration extends from the latent phase to full cervical dilatation (10 cm)
• Regular and active uterine contractions occur alongside cervical dilatation; both must be present for a patient to be in labor
• As the mother pushes down, the fetus is also pushed down, leading to cervical dilatation
• Subserved by T10 to L1 spinal nerves
• Visceral afferent sympathetic nerve fibers enter the spinal cord through T10, T11, T12, and L1
• Dilation, distention, stretching, and tearing of the lower uterine segment and cervix occur with contractions
• As the uterus contracts, pain is transmitted to the brain via spinal nerves
• Visceral pain is experienced during the first stage of labor
• Visceral pain characteristics include: vague, dull, aching, and poorly localized
• Fibers carrying the impulse are slow-conducting nerve fibers, caused by the dilatation of the uterus
• Pregnant mothers cannot pinpoint the specific location of visceral pain

Second Stage of Labor

• Duration is from full cervical dilatation to the delivery of the baby, which induces crowning
• Stretching of the perineum and pelvic floor muscles occurs
• Pain originates from pain-sensitive areas in the pelvic floor due to the baby pushing into the perineum and tearing tissues
• Subserved by the pudendal nerve (S2-S4 spinal nerves) and visceral afferent sympathetic nerve fibers
• The first stage sees nerves enter the spinal cord through T10-T12 and L1, creating action potentials transmitted to the brain
• The lower uterine part is subserved by the pudendal nerve and sacral nerves S2-S4
• Somatic pain is experienced during the second stage of labor, exhibiting sharpness and a similarity to skin abrasion pain
• Pain fibers are fast-conducting, caused by the uterus' dilation
• Somatic pain is well-localized, allowing the mother to describe the type of pain

Labor Pain Types

• First Stage: T10-L1 spinal nerves, visceral pain, distention, dilatation, tearing of the cervix and LUS.
• Second Stage: S2-S4 spinal nerves, somatic pain, pushing of fetal head against pelvic floor and perineal pain Labor Fibers:
• First Stage: Slow-conducting pain fibers & Poorly localized, dull and aching & Opioids, paracervical block
• Second Stage: Rapid-conducting pain fibers, well localized & Sharp sensation, Pudendal block

Labor Pain: Factors Influencing Perception

• Perception of labor pain is individualized and complex, dependent on culture, experience, emotional state, maturity, motivation, cognitive understanding, and socio-cultural factors
• Many women in the Philippines deliver at home without analgesia due to limited access to hospitals
• Patients in government hospitals commonly deliver without labor analgesia

What Affects Labor

• Uterine contraction paired with cervical dilatation occurs, which can lead to labor pain
• Mechanical stimuli convert pain signals to electrical, that goes to pain receptors and brain
• Blocking the transmission and use of analgesia are the strategies for pain relief
• Epidural or spinal and intravenous medications, as well as local anesthesia can deliver a good analgesia
• Providing analgesia is important to alleviate mothers pain

Physiological responses to pain of Labor

• Increases sympathetic stimulation from increased catecholamines:
• Maternal: cardiac output, vascular resistance, blood pressure, heart rate, breathing
• Pain has adverse effects on women with heart failure and uncontrolled hypertension.
• ↑ stress: ↓ placental perfusion, leading to fetal hypoxemia and acidosis
• Pain increases oxygen consumption that increases respiratory rate: catecholamines, heart rate, resistance, & blood pressure

Alleviating Labor Pains

• Prudent to give analgesia to the mother because it's very painful
• Physiologic responses to pain are detrimental to both mother and the fetus
• The pain can prevent the progression of labor
• Timely referrals to anesthesiology should be done

Third Stage of Labor

• Duration extends from delivery of the baby to that of the placenta, which produces uncomfort

Non-Pharmacologic Options in Pain Management

• Comfort measures are natural forms of pain relief
• They help the mother relax, feel better, and increase the production of endorphins that produce some pain relief
• Psychoprophylaxis and Lamaze are examples
• Lamaze emphasizes special breathing patterns and other natural relaxation techniques
• 9/10 who study Lamaze would opt for an epidural
• TENS and acupuncture control the pain pathway
• Aromatherapy, heat, cold, use vertical positions or any positions the patient feel most comfortable

Medications, Nitrous Oxide and others

• Provides some pain relief, but doesn't eliminate pain
• Use with caution if used concomitantly with opioids (not available locally)
• Some preparations are premixed, while others blend gases from separate tanks
• Intermittent nitrous oxide use did not alter epidural analgesia rates but improved experience satisfaction
• Maternal side effects include nausea, vomiting, dizziness, and drowsiness

Inhalational/Volatile Agents

• Anesthetics are in gaseous form that activates the brain or CNS which puts patients to sleep
• This can lead to respiratory and cardiovascular depression
• Not recommended for mothers with heart failure
• In extreme emergencies like in fetal anoxia or hemodynamically compromised mothers
• There is a risk of pulmonary aspiration of gastric contents

Opioids

• Opium derivatives (poppy plant) are the most widely used systemic medication
• Maternal Side Effects:Pruritus, nausea and vomiting, delayed gastric emptying, respiratory depression, dysphoria & incomplete analgesia
• Since drugs cross the placenta, neonatal effects is respiratory depression & neurobehavioral changes

Regional Anesthesia

• This is to provide patient satisfactory pain relief, and may have small risks
• Involves blocking the area where signals are transmitted using local and other types of anesthesia
• There is small risk to both mother and fetus
• Has little interference with the progress of labor

Local Infiltration

• Most common technique administered for vaginal deliveries that may be performed by obstetricians
• During the crowning phase 5-10 mL local anesthetic injected subcutaneously at fourchette and perineal muscles for episiotomy
• Also administered in cases of failed pudendal block and epidural anesthesia
• Lidocaine is used

Paracervical Block

• Rarely conducted, the short acting analgesia is often repeatedly applied
• Blocks nerve transmission through the Frankenhauser’s ganglion, lateral to the cervicouterine junction
• Analgesia for the pain of cervical dilatation and uterine contractions of the 1st stage of labor
• Complications may incluse fetal bradycardia, toxicity, neuropatmy or fetal injury
• During procedure, lidocaine is injected at 10, 8, 2 & 4 o’clock positions to block uterine contraction to the sympathetic chain that lasts 60-90 mins
• Ketorolac enhances the analgesia

Pudendal Nerve Block

• Blocks the pudendal nerve where pain transmitted from S2-S4 spinal, easier to apply than paracervical
• Used when head is fully presented at delivery for pain
• Dose of local anasthetic is 7-10mL on each side, providing relief for forceps
• Complications: hematoma due to trauma & infections at injection

Contraindications for performing the block

• Identify ischial spine first and trumpet needle to insert through it to the tissue where 1% lidocaine gets injected
• A spinal needle with an Iowa trumpet can be used at 2,4,8,10 positions with lidocaine
• This helps to locate vaginal fornice to know spinal insertion point

Local Anesthetics, sites of action and safety

• Agents cause limited sensation loss & helps block the pain sensation
• Always check the excess dose being administered to patients due to systemic toxicity that later would lead to cardiac arrest
• Spinal nerve trunks, the ganglia , spinal roots are potential sites for admin

Neuraxial Blocks

• Gold standard for labor analgesia that blocks communication of the pain to mother so feel content
• Act where mother feel drowsy and regional where they do not know of the block

Spinal Anesthesia

• The spinal needle must reach the spinal fluid, the CSF and LLD position is necessary
• The anesthetic depends on sensation Can be performed for vaginal and cesarean deliveries
• Higher sensory is lower motor block

Lumbar Epidural Anesthesia

• Can be administered if patients are struggling to bend
• There is the epidural where you’re close to CSF
• Note that the high concentrations mean the lower motor block and give the lowest concentration that allows patients to breathe
• A pump can also be attached and used to control by the person

Epidural Nerve Blocks

• Spinal needle goes to subarachnoid of the root
• While epidural goes near spinal cord on the dura, requiring more anesthetic and needs catheter

Combined Spinal Epidural Anesthesia

• For fast and immediate pain relief that requires anesthetics
• Procedure: needle is inserted into the dura, anesthetic is released within
• Anesthesiologisrs give a very thin tube that can run through the epidural section

Pain Control

• The pump allows control of local pain, providing early control and interaction in the newborns body
• The passages also have to be easier during this transition
• The motor should also ensure function for each step
• Programmed infusions are given and pump also connected

Saddle Block and Complications

• Use of block also creates fever abnormalities and hypotension
• Its common and higher with post operation levels and increased in pregnanices

Programmed Intermittent Epidural Bolus Pump

• Provides continuous boluses that includes high does of test using Epinephrine

Contraindications of neuraxial

• Absolute is maternal refusal, coagulopathy, thrombocytopenia, bacteremia and infections
• Relative is the therapy of those effects of those medications
• Neuromusclar and spinal infections that alter the nervous processes