Pain relief in labour
Introduction:
Pain is the sensation of discomfort. It is a subjective, personal symptom; what the
person says it is, and present when the person says it is. It is unique to each individual
so only the woman can describe or know the extent of her pain. To assess the amount
of discomfort a woman is having in labor, listen to what she is saying. Also look for
subtle signs of pain such as facial tenseness, flushing, or paleness, hands clenched in
fists, rapid breathing, or rapid pulse rate. Knowing the extent of a woman's discomfort
helps to guide nursing care.
Physiology of Pain:
Sensory impulses from the uterus and cervix synapse at the spinal column at the level
of T-10, T-11, T-12, and L-1. Pain relief measures for the first stage of labor, therefore,
block these upper synapse sites. For the elimination of pain during cesarean birth,
receptors at the level of T-6 to T-8 must be blocked so the upper and lower uterus is
blocked.
Sensory impulses from the perineum are carried by the pudendal nerve to join the
spinal column at S-2, S-3, and S-4. Pain relief for birth, therefore, when the perineum is
initiating the pain, must block these lower receptor sites. This is an important point to
remember when talking to women in labor about pain relief. Some interventions relieve
pain for both the first and second stages of labor, whereas others work for first or
second stage but not for both.
Labor Pain during Different Stages of Labor:
Traditionally, labor has been divided into three stages. The first stage is defined as that
lasting from the start of regular uterine contractions until the completion of cervical
dilatation. It is commonly subdivided into a latent and an active phase, the latter being
characterized by a rapid acceleration of cervical dilatation. The second stage proceeds
from the first stage until the delivery of the fetus is complete, and the third stage
continues until the placenta and membranes have been expelled. Pain during the first
stage of labor is visceral and is therefore mediated by the T10 through L1 segments of
the spine, whereas during the later part of the first stage and throughout the second
stage, an additional somatic component is present, mediated by the S1 through S4
segments of the spine. Active pain pathways are marked in red.
Factors Influencing Pain Perception:
Labor pain is the result of a complex and subjective interaction of multiple physiologic
and psychological factors:
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Fetal position is a physical variable that can influence pain. A woman with a fetus in
an occiput posterior position, for example, often reports intense or nagging back
pain during labor, even between contractions.
-
Poor physical condition, fatigue, tension, and malnutrition are all associated with
increased pain in labor.
Non Pharmacologic Pain Relief:
Non pharmacologic measures for pain relief include interventions that may be used as a
woman's total pain management program or used to complement pharmacologic
interventions. Most of these interventions are based on the gating control theory
concept that distraction can be effective in preventing the brain from processing pain
sensations coming into the cortex.
Relaxation: Relaxation keeps the abdominal wall from becoming tense, allowing the
uterus to rise with contractions without pressing against the hard abdominal wall. It also
serves as a distraction technique because, while concentrating on relaxing, the woman
cannot concentrate on pain.
Focusing and Imagery: Concentrating intensely on an object is another method of
distraction or keeping sensory input from reaching the cortex of the brain.
Support: Mother husband has traditionally serve as chief support person in labour.
Breathing techniques: They are advantageous because they help to relax the
abdomen.
Heat or Cold Application: Heat and cold have always been used for pain relief after
injuries such as minor burns or strained muscles. It is only lately that they have been
considered an effective way to help relieve the pain of labor contractions.
Bathing or Hydrotherapy: Standing under a warm shower or soaking in a tub of warm
water or a jet hydrotherapy tub is another way to apply heat to help reduce the pain of
labor. The temperature of water used should be between 98°F and l00°F (36.6°C and
37.8°C) to prevent hyperthermia.
Therapeutic Touch and Massage: Therapeutic touch is the use of touch to comfort
and relieve pain. It is based on the concept that the body contains energy fields that,
when plentiful, lead to health and when in less supply, result in ill health.
Hypnosis: It is infrequently used.
Biofeedback: It is based on the belief that people have control and can regulate
internal events such as heart rate and pain response. Women interested in using
biofeedback for pain relief in labor must attend a number of sessions during pregnancy
to condition themselves to regulate their pain response.
Transcutaneous Electrical Nerve Stimulation (TENS): It is another method to
achieve pain relief in labor. With two pairs of electrodes taped to the woman's back to
coincide with the T l0 - L l nerve pathways, low-intensity electrical stimulation is given
continuously or applied by the woman herself as a contraction begins. This stimulation
blocks the afferent fibers, or prevents pain from traveling to the spinal cord synapses
from the uterus.
Acupressure & Acupuncture: Acupuncture is based on the concept that illness results
from an imbalance of energy. To correct the imbalance, needles are inserted into the
skin at designated susceptible body points (tsubos). Acupressure, in contrast, is the
application of pressure or massage at these points. A common point used for the
woman in labor is Co4 (Hoku or Hegu point) located between the first and second
metacarpal bones on the back of the hand.
Pharmacologic Pain Relief During Labor:
Pharmacologic management of pain during labor and birth includes analgesia, which
reduces or decreases awareness of pain, and anesthesia, which causes partial or
compete loss of sensation.
Virtually all medication given during labor crosses the placenta and has some effect on
the fetus. Thus, it is important that a woman receive as little medication as possible
during labor.
Goals of Pharmacologic Management:
Medication effectively used during labor must relax the woman and relieve her
discomfort, yet have minimal systemic effects on her uterine contractions, her pushing
effort, or the fetus. Whether a drug affects the fetus depends on its ability to cross the
placenta.
Local anesthesia:
Epidural Anesthesia:
•
Epidural anesthesia is a process in which a narcotic or local anesthetic is injected
into the back, just outside the dura, which is the membrane that protects the
spinal canal.
•
To administer the epidural, a woman is first given intravenous fluids to help prevent
a drop in her blood pressure. She is then asked to lie on her side or sit with her
back arched.
•
A local anesthetic is injected into the skin to numb the area and prepare it for the
epidural.
•
A needle is then inserted between the vertebrae in the woman's back and a
catheter is inserted through it into the epidural space.
•
Medication is continuously injected through the catheter.
•
The epidural is usually administered after the woman's cervix has dilated to 4 or 5
centimeters.
Benefits:
1. Usually provides effective pain relief.
2. A small amount of medication is used, so the woman remains mentally alert.
3. Safer than general anesthesia and can be used for cesarean sections.
4. Requires less time to recover than with general anesthesia.
Risks to the Mother:
1. May provide inadequate or patchy pain relief.
2. Possible fever.
3. Possible serious drop in blood pressure.
4. Causes immobility (less so with the "walking epidural").
5. May increase the likelihood of malpresentation.
6. Has been shown to prolong labor by an average of 2 hours.
7. Since it may interfere with progress, increased need for pitocin.
8. Increased need for forceps and vacuum extraction.
9. May increase the need for cesarean section (The studies are contradictory on
this point).
10. Possible shivering or itching.
11. Possible severe post birth headache ("spinal headache").
12. Increased risk of long-term backache.
13. Usually requires urinary catheterization.
14. Requires continuous monitoring to detect complications and gauge progress.
15. Reduces the experience of birth.
16. Severe complications are extremely rare, but include seizures, paralysis of the
lungs and heart and death.
Risks to Baby:
1. Medication crosses the placenta.
2. Risk of septic workup and NICU care if maternal fever develops.
3. Increased risks due to forceps, vacuum or cesarean section.
4. Possible respiratory depression.
5. Increased likelihood of fetal distress if mother's blood pressure drops.
6. Possible short-term neurobehavioral changes including irritability and
inconsolability.
Spinal Anesthesia:
•
In a spinal, pain medication is injected directly through the dura into the spinal
canal. It is a one-time shot that usually wears off in about an hour or two.
Benefits:
1. Easier to perform than an epidural.
2. Takes effect much faster, making it a better choice for cesarean section in some
cases.
3. Usually eliminates the sensation of pain completely.
Risks to Mother:
1. All the same risks as an epidural
2. Spinal headache
Risks to Baby:
•
Same as epidural.
Combined spinal-epidural analgesia:
•
A technique called "walking epidural" is a combined spinal-epidural analgesia. It
works fast, blocking pain in the abdominal nerves (not the whole lower body) and
usually allows the patient to move around the room if desired.
•
The first step is an injection of narcotic or anesdiedc. A catheter is then placed in
the epidural space for a regular epidural, should additional pain medication be
needed later. This technique can cause the same side effects as mentioned in
epidural and spinal blocks.
Pudendal block:
•
A Pudendal block is injected shortly before delivery to block pain in the perineum
(the area between the thighs that lies behind the genital organs and in front of the
anus). It is especially helpful for numbing the perineum before birth. It relieves pain
you may have around the vagina and rectum as the baby moves through the birth
canal.
•
Pudendal block is one of the safest forms of anesthesia. Serious side effects are
rare. A Pudendal block should not cause changes in your baby's heart rate.
Narcotic Analgesics:
•
Narcotic analgesics like pethidine, morphine etc. are administered through an IV or
injected directly. They do not eliminate pain, but are meant to "take the edge off".
•
They are sometimes tried before more invasive anesthetics.
Benefits:
1. May "take the edge off" pain.
2. May promote relaxation, especially between contractions.
Risks to Mother:
1. Drowsiness, confusion.
2. Nausea, vomiting.
3. May slow the progress of labor.
4. May reduce coping abilities.
5. Possible respiratory and central nervous system depression.
Risks to Baby:
1. Possible depressed fetal heart rate.
2. Possible respiratory depression.
3. Possible lack of responsiveness for up to a week.
General anesthesia:
•
It is never preferred for childbirth, because it carries the dangers of hypoxia and
possible inhalation of vomitus during administration. Pregnant women are
particularly prone to gastric reflux because of increased stomach pressure from the
weight of the full uterus beneath it. The gastroesophageal valve also may be
displaced and may be functioning improperly.
•
Despite these risks, general anesthesia may be necessary in emergency situations
such as an abruptio placentae requiring an immediate cesarean birth.