Pharmacologic Pain Relief during Labor
Epidural Anesthesia or Peridural Block
Anesthetic agents introduced into the spinal canal are epidural anesthetics. They are administered at either the following sites:
These areas contain not only the spinal nerve roots but sympathetic nerve fibers also travel with them. Thus, epidural anesthesia provides pain relief not only during labor but also during actual birth. It is a very effective pain relief during labor because when the woman no longer experiences pain the release of catecholamines with a B-blocking effect from a pain response is also decreased.
Epidural blocks are administered by an anesthesiologist or nurse-anesthetist and is suitable for all women. Women with heart disease, pulmonary disease, and diabetes and sometimes those who have pregnancy induced hypertension find epidural blocks advantageous. However, the major concern with this drug is its tendency to produce hypotension. The blocking effects on the sympathetic nerve fibers in the epidural space lead to decreased peripheral resistance in the woman’s circulatory system. As a result, blood flows freely into the peripheral vessels and a pseudohypovolemia develops which the body registers as hypotension.
Hypotension can be prevented and managed by performing the following:
- Combined use of fentanyl and bupivacaine – can lower the risk of hypotension
- Making sure that the woman is well hydrated with 500 to 1000 ml of I.V. fluid such as Lactated Ringer’s solution before the anesthetic is administered
- Proper positioning of the pregnant woman: be certain that the woman lies on her side after an epidural block to help prevent supine hypotensive syndrome.
- In cases where hypotension occurred, the nurse should raise the woman’s legs, administer oxygen and increase IV fluid.
- To elevate the blood pressure, an agent such as ephedrine may be necessary to stabilize the circulatory status of the patient.
This is the injection of an anesthetic such as Lidocaine (Xylocaine) into the superficial nerves of the perineum. Local infiltration is used when the fetal head is too low to allow pudendal block. The anesthesia is administered along the borders of the vulva and it takes effect for approximately 1 hour.
Pudendal Nerve Block
Pudendal nerve block is the administration of an anesthetic agent such as chloroprocaine (Nesacaine) or bupicaine (Marcaine) near the right and left pudendal nerves located at the level of the ischial spines.the technique provides perineal pain relief in about 2 to 10 minutes that lasts for approximately 1 hour. Use of low forceps during birth and episiotomy repair has been painless with the use of this method.