Labor Epidural Basics

Some of the women that come to Lakeside Women’s Hospital to deliver their first child are frightened by the idea of having a labor epidural. Much of this relates to the patients simply fearing the idea of having a needle stuck in their backs. Other patients tell us they have heard “horror stories” about epidurals-gone-bad. It is not uncommon for a patient to tell us that the epidural was the thing that had worried her most about the whole upcoming delivery process. For women who have previously experienced childbirth with the benefit of an epidural the story is quite reversed. They are more likely to yell, “Epidural Now!” when they first hit the door of the delivery suite. By sharing this information, we hope to help first-time moms be better prepared and more like the experienced moms. That is, at ease with their anesthetic options before they come to the hospital. We do not claim that every woman should have an epidural. That is the individual woman’s personal choice. We simply present this information so that women can make informed choices based on solid information rather than myth and legend.

History

Epidural anesthesia has been around for a long time. It was first discovered early in the 1900s, but not widely applied. In the 1950s and 60s, one-shot Caudal Blocks for delivery were done with lidocaine (trade name xylocaine). A caudal block is a form of epidural block that is placed at the top of the tail bone. However, epidurals as we know them today, didn’t really catch on until the 1970s. The limiting factor had been the development of the technology to make an epidural catheter (plastic tube) sturdy enough and small enough to cause minimal tissue damage, yet with a big enough hole in the middle to deliver the needed medication. Labor epidurals also made a major advance in the 1980s when we began combining newer, long-acting local anesthetics with narcotic pain medicines. By the mid-1980s, epidural anesthesia had become the standard in pain relief for labor and delivery.

How It’s Done

Before placing an epidural, we numb the skin by injecting lidocaine through a very skinny needle. This part stings for about 10 seconds and by the end of that time the tissues become numb and stop stinging. Then there is a second, deeper injection of numbing medicine that doesn’t sting as much as the first one. After that, the epidural needle placement causes little discomfort. Most women say that having the IV started was more painful than the entire epidural placement process. The epidural needle is placed between two spine bones in the low back, usually somewhere between the 2nd lumbar vertebra and the sacrum, (L2 to S1).  The tip of the needle is inserted into what we call the epidural space. It isn’t really a space in everyday life. It is really just the contact between the dura mater and the ligament that touches it on its outward facing surface. When the needle goes through the ligament, it creates the space by “tenting” the dura. Dura mater is a term you might have learned for a test in high school biology and then forgot as soon as the test was over. It is the outermost and toughest of the three layers that cover and protect the brain and spinal cord. The name epidural comes from the Latin “epi” (on top of) and “dura” (hard). A thin plastic tube (epidural catheter) is slipped into the epidural space through the needle and the pain-relieving medicine is injected through the catheter. This medicine doesn’t affect the spinal cord directly. Instead, it seeps around to the sides of the spinal cord and blocks the nerves where they leave the dura to go out to the body.  Once the medicine is in the epidural space, pain relief usually begins within 10 minutes or 3 contractions. It takes about 20 minutes before the full effect is obtained.

    Windows or Hotspots

    Epidurals are not perfect. They are not 100% effective. They almost always give a great deal of pain relief to the patient, but they are not perfect. In fact, you should expect to be a little more numb on one side of your body than the other. That is totally normal and expected. If you are not hurting, don’t worry about it. On the other hand, it is possible to have spots that aren’t numb at all. Since the nerve roots are blocked individually rather than all at once like they are with a spinal block, it is possible to miss blocking some of these nerves. If you have talked to enough women who have had labor epidurals, then you have found at least one who had a spot that never got numb enough to block all the pain in that spot. The anesthesia lingo for these unblocked areas is a “window.”  The causes of windows are often not known, but may be due to the epidural being placed a little more to one side than the other. It is very difficult to place epidurals exactly in the center of the epidural space every time. Since we can’t see the space, placement of the epidural has to be done by feel. Another possible cause of windows is due to naturally occurring little strips of tissue in the epidural space that act as room dividers, preventing the medicine from reaching every part of the epidural space. Occasionally, we have to replace epidurals to get rid of the pain and in some cases, we never get rid of all the pain.

    Medications Used

    The medicines most commonly used are bupivacaine and ropivacaine. They are local anesthetics like lidocaine, but longer lasting. They are commonly mixed with a narcotic pain reliever such as fentanyl. At Lakeside, we routinely use ropivicaine mixed with sufentanyl. We administer them with a continuous infusion pump, that has a PCA (Patient Controlled Analgesia) button that will allow you to give yourself extra medicine as you need it. However, we want your nurse to be in the room with you when you push the button because it really matters what position you are in when you push it. The pump usually keeps the patients comfortable, but if the continuous dose isn’t enough, you may call your nurse into your room and you can push the button. We recommend pushing the button and waiting 10 minutes. If the pain persists, push the button again. If still no relief, your anesthesiologist will come back to your room to give a larger dose and perhaps a stronger drug.

    After the Baby Is Born

    Once the baby is born, your nurse will pull your epidural catheter out and the drugs wear off over a period of 2-3 hours. If you and your doctor have scheduled you to have a tubal ligation in the next few hours after birth, the epidural catheter may be left in so it can be used as the anesthetic for the tubal.

    C-section Following Labor

    If you have an epidural already in place and the need arises for you to have a C-section, the epidural can usually be used for the anesthetic.  A more concentrated local anesthetic is injected through the epidural and given time to work (10 -20 min). If you are not numb enough for surgery after the medicine has been given ample time to work, then a different anesthetic will have to be used, (replace the epidural, spinal anesthetic or general anesthetic). In the case of an emergency C-section where there is not enough time for the additional epidural medication to work, a general anesthetic is used.

    Anxiety in First-time Moms

    Many first-time moms come to delivery more worried about the epidural than anything else. Some are frightened enough that they go without, not because they want to “go natural,” but because they are scared of the epidural. The size of the needle is another reason they often given. True, the needle is about as big around as a pencil lead in a standard wooden pencil and it’s about 5 inches long. With the numbing medicine being injected first, the actual placement of the epidural needle is minimally uncomfortable.

    As mentioned in the introduction, the second, third, and forth-time moms generally come through the door of the labor and delivery unit saying, “Get the anesthesiologist in here. I want my epidural now.” Very few women who have had an epidural with previous children, choose to labor the next time without one.

    Ineffective Epidurals

    Sometimes epidurals don’t work as well as we would like them to. In these cases, the patients may say, “my epidural wore off” or “my epidural only numbed one side.” However, when asked if the women who reported these problems hurt less than if they had not had an epidural at all, the answer is almost always that it did help to some degree. Also, the average effectiveness of a particular anesthesiologist’s epidurals improves over time.  Most of the “horror stories” are motivated by anesthesiologists or nurse anesthetists with minimal experience. The anesthesiologists of OKC Anesthesia have each done hundreds of epidurals and some of us have done thousands.

    Common Reasons for Inadequate Pain Relief

    • The patient delivers before the epidural has had sufficient time to work.
    • The woman has an anatomic abnormality that physically screens off part of her epidural space from the medication.
    • The epidural needle placement is too far to one side.
    • The epidural catheter tip comes to rest too far to one side of the epidural space.

    The last two examples are due to the fact that it is difficult, even in expert hands, to get the epidural exactly in the midline without X-ray guidance. We don’t use X-ray in OB anesthesia, because it usually isn’t necessary and because we don’t want to expose the baby to unnecessary radiation if we don’t really have to.

Side Effects

    Nausea and Lightheadedness

    These two are very common in labor, even without an epidural. If they occur with an epidural, they may be caused directly by the narcotic pain medication in the epidural or indirectly by a drop in blood pressure. The drop in blood pressure is caused by numbing of nerves that help keep blood vessels tight and toned. The blood vessels relax and allow excess blood to pool in them. It is for the prevention of this drop in BP that about a liter of IV fluid is given before placement of an epidural.

    Itching

    The narcotic pain medicine in the epidural mixture may directly stimulate the brain’s itch center. If it happens, we have drugs to make it better.

Complications

The complication rate of labor epidurals is extremely low, but complications are possible. Here are some of the more common ones.

    Unintended Injection of Local Anesthetic into a Vein

    Sometimes the tip of the epidural catheter will slip into a vein in the epidural space. This event is usually readily recognized by the anesthesiologist. It is the reason why a test dose is done. That is where a small amount of local anesthetic is injected through the catheter before it is dosed, to see if there is any abnormal reaction. The catheter tip can work its way into a vein over the duration of labor from the patient moving. If the catheter is in a vein and local anesthetic is injected or infused by the epidural pump, the patient will feel strange, hear ringing in her ears and perhaps have a metal taste in her mouth. This will alert the nurses to get the anesthesiologist to come evaluate the patient.

    Nerve Injury

    Probably the most concerning of all the possible side effects of having a needle placed in one’s back is injury to a nerve or the spinal cord. This is an extremely rare event, in the range of 1 in 10,000 for permanent, serious nerve injury caused by the epidural. Nerve injury is actually much more commonly caused in labor by the continued pressure of the baby’s head pressing on the nerves to the legs as they cross the pelvic bones internally. Another common cause is pressure from the stirrups on nerves near the surface of the lower leg. This can happen when the woman has her feet in the stirrups while pushing for an extended period of time, usually more than two hours.

    Back Injury

    Usually, the area where the epidural is placed is sore for a few days, just as it would be if one had been given a shot in that area, then it goes away. However, some women can still point to the spot where they got their epidural years before. They generally say it’s still a little sore in that spot, sometimes worse than others, but not much more than a minor annoyance.

    Trigger Points

    Rarely, the soreness at the site of the epidural placement continues or increases over time. This is usually due to the formation or the beginnings of a Trigger Point. A trigger point is a small scar in the ligaments and or muscle in the area. It can cause a vicious cycle where pain and inflammation cause spasm of the surrounding muscles which, in turn, causes more pain, which causes more spasm and so on. This can become a serious problem. The pain can become debilitating if not treated. If treatment is begun within a month of its onset, a full recovery can be expected. If left untreated, it can become a permanent, recurring pain. Trigger Points often form in the neck and shoulder muscles after car wrecks or repetitive office work that requires a lot of looking down at the desk. Trigger points are also associated with the childbearing process and can be due to multiple causes.

    • Neck and shoulder Trigger Points can be due to carrying the child in the same arm all the time or from holding the baby in an uncomfortable position while breast feeding.
    • Low back Trigger Points can be caused by pregnancy itself and carrying the baby with the more prominent curve in the back.
    • Low back Trigger Points can also be caused by pushing at the end of labor or injury to small back muscles while moving and straining during labor.

    Headache

    The headache that can be caused by an epidural is the same as that caused by a spinal tap. What happens is the epidural needle goes a few millimeters too far on into the spinal fluid. This is called a dural puncture. It is not generally our intent to do this, but it happens on occasion. It happens more commonly in obese patients where the usual landmarks are obscured and it is more difficult to feel the normal anatomy. If the dura is punctured and spinal fluid is released, that can cause a decrease in pressure in the head and thereby cause a headache. These headaches will almost always go away on their own without treatment, however that could take a couple of weeks. Most patients don’t want to lie in bed for that long waiting to recover, so an Epidural Blood Patch is another option.

    Epidural Blood Patch

    This is where an epidural needle is placed in the back near the original puncture site, but in the epidural space instead of the spinal fluid. A syringe of the patient’s own blood is injected through the needle where it forms a clot that “patches” the leaking hole in the dura. The relief is almost immediate, because the injected blood pushes spinal fluid up into the head equalizing the pressure. The ultimate effectiveness of the blood patch is not quite as dramatic. Permanent cure results range between 65% and 90% in various studies.