分娩镇痛.ppt

1、LABOR ANALGESIA,XIANG YA HOSPITAL Dr. YAN,LABOR PAIN PATHWAYS,First stage: -pain is due primarily to uterine contractions that cause stretching and thinning of the uterine cervix. -pain impulses travel via visceral afferent fibers and enter the spinal cord at the T10 ,T11 and L1spinal segments. -pai

2、n is generally poorly localized and is dull or cramping.,LABOR PAIN PATHWAYS,Second stage: -Stretching of the perineum produces additional pain,more somatic in nature,is well localized and sharp - these impulses travel via the pudendal nerves from the S2,S3andS4spinal segments,LABOR PAIN,The amount

3、of pain experienced by a woman during labor and delivery can be influenced by many factors,including participation in childbirth preparation classes,parity,and use of oxytocin,ANALGESIA FOR LABOUR PAIN,Psychologic techniques -hypnosis -psychoprophylaxis -positive conditioning -patient education -acu

4、puncture -trenscutaeous electrical nerve stimulation,Systemic medication,Benzodiazepines -diazepan crosses the placenta rapidly,and maternal and fetal blood levels are equal within minutes of an IV dose if total maternal dosage exceeds 30mg, the drug and its active metabolite persist in pharmacologi

5、cal active concentrations for at least a week in the neonate,Systemic Medication,Diazepam -the adverse effects in neonate: .in large dose: hypotonia, lethargy, decreased feeding,and hypothermia .in small dose:reduced beat-to-beat variability. Midazolam -if it is used for induction,problem with genra

6、l body tone and body temperature of neonate seen.,Systemic Medication,Meperidine -peak analgesia effect occurs 40 to 50 minutes after Imand 5 to 10 minutes after IV -the duration is 3-4hours -can cause dose-dependent neonateal depression, as evidenced by prolonged time to sustained respiration,decre

7、ased Apgar scores,and abnomal results from neurobehavioral examination,Systemic Medication,Fentanyl -50ug to 100ug Imand 25ugIV -peak effect(IV)3-5min and duration 30-60min -A dose of 1ug/kg Ivto the mother within 15 min of cesarean delivery did not produce adverse effects -newborn drug levels were

8、always less than maternal levels,Systemic Medication,Morphine -peak analgesic effect occurs 1-2hoursIM and 20minutesIV -duration is 4-6hours -in equianalgesia doses,morphine produces more respiratory depression of the newborn than doses meperidine -morphine is reserved for early labor,Systemic medic

9、ation,Butorphanol and nabuphine -synthetic agonist-antagonistnarcotic analgesics -do not cause respiratory depression in labor pt -cause maternal dizziness and somnolence and adverse neonatal neurobehavioral effects -rapidly cross placenta and increase FHR(cause high out put cardiac failure) -no adv

10、antage over other opioides,Systemic Medication,Ketamine -low dose Ivketamine (10-25mg, or 0.25mg/kg increments) can be used with inhaled agents to produce analgesia (which can be useful during operateive vaginal delivery or cesarean delivery),Systemic medication,Inhaled analgesia -proper administion

11、 of inhaled analgesia by mask in low concentrations to prevent loss of consciousness and protective aieway reflexes. -vomiting or silent regurgitation are possible aspiration risk -nitrous oxide in 50%with oxygen,reliable analgesia has not been demonstrated,Regional anesthesia,Most effective -provid

12、e pain relief, keep patient awake and allow patient to participate in the labour and delivery process Unlikely to produce drug-induced depression in the fetus or mother Reduce levels of catecholamines in the mother ,which may beneficial to fetus,Regional anesthesia,Early placement of epidural cathet

13、er helps control blood pressure with good analgesia for labor pain in pre-eclampsia patient(after well hydration and before coagulopathy occurs) It may be the means to reduce cesarean section rate in China,Regional anesthesia,Patient preparation -IV -equipment for resuscitation and complication -O2,

14、airways,laryngoscope,endotracheal tubes,suctioning apparatus,thiopenal or diazepam,ephedrine and naloxone -preanesthetic evaluation, OB plan and understand fetal status -BP, ECG and FHR and 500ml IV fluid,Regional anesthesia,Contraindications -absolute .patient refusal, infectin at the site of needl

15、e placement, overt maternal coagulopathy, and maternal hemodynamic instability -relative .preexisting neurologic disease, prior back surgery,isolated coagulation abnomalities, some cardiac disease,Regional anesthesia,Timing of administration -chestnut et.al. performed a study wherein patients were r

16、andomized to early (ie,1st request0epidural or late (waiting until at least 5cm cervical dilation).No difference in cesarean rates was found between the two groups for either spontaneous or induced labors,and the cesarean rate was low (approximately 8%)in both,Regional anesthesia,Encourage early adm

17、inistration of epidural anesthesia in laboring women with preeclampsia Epidural anesthesia did not increase the incidence of cesarean delivery or pulmonary edema among laboring women with severe hypertensive disease,Regional anesthesia,One shot spinal analgesia using a lipid soluble opioid is rapid

18、and simple, but is associated with a limited duration of action,Regional anesthesia,Epidural analgesia provides excellent pain relief and the ability to extend the duration of the block to match the duration of labour ,but it is not “instant “in onset and may be associated with motor block,Regional

19、anesthesia,The combination of epidural and spinal anesthesia into one technique,termed “combined spinal-epidural provides the advantages of a spinal with the additional flexibility of renewal with an epidural catheter,Regional anesthesia,Intrathecal narcotic provides excellent pain relieve instantly

20、 without motor block CSE has special benefit if patients cervical dilation is about 8cm More than 60% of patients in my hospital receive CSE analgesia now,Regional anesthesia,Intrathecal opioids -sufentanil 2.5ug-10ug -fentanyl 10-25ug Side effects prurtus,nausea/vomiting,hypotension,urinary retenti

21、on,uterine hyperstimulation and fetal dradycardia,maternal respiratory depression,Epidural anesthesia,The block is placed once the patient is in established labor. Low doses of local anesthesics or opioids are often sufficient during the first part of labor to provide an effective T10-L1 segmental b

22、lock. Increased local anesthetics to cover S2-S4 for second sstages of labor,Epidural analgesia,Use dilute local anesthetics and opioid solutions(0,125%bupivacaine or ropivacaine with fentanyl or sufentanil) Make every dose a test dose -2-3ml initial bolus(look for intrathecal injection),Epidural an

23、algesia,Value of epinephrine “test dose”(15ug produce increased heart rate of 20-30/min) in the parturient ,epinephrine produces an indistinct tachycardia,which can be confused with pain-induced heart rate changes -epinephrine produces a more readily detected tachycardia if patients are already pain

24、free(afterantrathecal drug injection),Epidural analgesia,Epidural opioids for labor -meperidine 100mg-last 2.5hours -fentanyl 100-200ug,onset 5-10min,last 1-2hours -sufentanil5-15ug last 1hr,40-50ug last 5hr.,Epidural analgesia,Bupivacaine -long duration,lower motor block than lidocaine -beware of c

25、ardiotoxicity and do not use the concentrarion of 0.75% .lidocaine -most common used for cesarean delivery,Epidural analgesia,2-chloroprocaine -ester type,fast onset,brief duration -useful to rapidly extend a labor epidural block for operative vaginal(2-3%)or cesarean(3%)delivery -a disadvantage is

26、it apprarent antagonism of subsequently injected epidural opioids and bupivacaine,Epidural analgesia,Ropivacaine newer amide local anesthetics similar in structure ,potency,and pharmacodynamics to bupivacaine cardiotoxicity that is intermediate between those of lidocaine and bupivacaie,Epidural anal

27、gesia,Continuous epidural infusion -0.04%bupivacaine plus fentanyl:almost all patients will require at lease one resuse bolus,some need more than seven -0,083%bupivacaine plus sufentanil:53%requre at least one rescue,18%need two or more -complication:intravascular or intrathecal infusion,Epidural an

28、algesia,Patient controlled epidural analgesia minimize drug dosage.flexibility and benefits of self administration reduced demand on professional time controversy still exists regarding the use of a continuous basal infusion in addition to patient controlled boluses which would provide for a more ev

29、en block and larger doses,Epidural analgesia,Complications -hypotension -convulsion -cardiac arrest deliver the fetus,external cardiac massage defibrillation epinephrine bretylium -total spinal airway,trendelenburg,fluid,pressure support,Epidural analgesia,Complications nerve injury rare epidural hematoma infection, meningitis headache,Regional anesthesia,CSE rapid onset reliability patient can walk if only intrathecal opiate given (in Ob patient) epinephrine test dose for epidural catheter placement is more reliable after intrathecal opiate is