Local anesthetics in epidural anesthesia for pregnant women
Basically, epidural anesthesia (PDA) is performed with the same technique as epidural anesthesia for non-pregnant women. However, there are a few special features that should be taken into account in pregnant women. During epidural surgery, pregnant women are advised to administer fluid quickly through a vascular access.
It has been found that about 80% of the fluid given passes quickly from the vessels into the tissue. Since PDAs, especially pregnant women, often cause a sharp drop in blood pressure through the epidural, it is preferable to give the fluid during the epidural rather than before it. The drop in blood pressure is due to the blockage of the sympathetic nervous system caused by the medication of the epidural.
Pregnant women are usually placed in a sitting or left-side position. Puncture for the PDA is more difficult for pregnant women than for non-pregnant patients. Due to the hormonal changes in pregnant women, water retention is often present in the tissue.
In addition, the tissue and ligament structures are usually softer and looser. Thus the decreasing resistance during puncture is more difficult to localize due to the loosened tissue. The risk of malfunctions is therefore increased.
Therefore, PDA puncture in pregnant women should be performed by an experienced anesthesiologist. Bupivacaine and ropivacaine are administered as local anesthetics.These local anesthetics have optimal criteria for not being transmitted to the child. In the case of vaginal delivery, there is the peculiarity that the local anaesthetics are administered only in small doses, so that only the nerve fibres for pain and temperature are blocked, but the patient can still actively use her muscles to support the birth through an abdominal press.
The local anesthetic is always administered during the breaks in labor. This is important because the pressure of the contractions can cause the local anesthetic to rise uncontrollably upwards through the spinal canal! Sometimes additives of sufentanil are also used.
This results in better pain relief. The maximum dose here is 30 μg. To reduce the pain during the opening contractions, one normally blocks the pain transmission from the 10 thoracic vertebrae to the 1 lumbar vertebra.
Approximately 6-8 ml of 0.25% bupivacaine or 0.2% ropivacaine are required for this purpose. To reduce the pain in expulsion contractions, the pain transmission from the 10th thoracic vertebra to the 4th sacral vertebra is blocked. Approximately 12 ml 0.25% bupivacaine or 0.2% ropivacaine is used.
The pain therapy with the local anesthetics bupivacaine and ropivacaine lasts for about 2 hours. If necessary, more must be administered after 2 hours. The epidural guarantees a painless birth.
The epidural is also advantageous in the case of birth from pelvic end position, premature birth, (diabetes), EPH gestosis (triad of high blood pressure, water retention, high protein excretion), multiple pregnancies, in the case of lung or heart diseases of the pregnant woman and in diseases where too much pressing during the birth process would be disadvantageous. Basically, a vaginal delivery with an epidural is not performed in the case of In addition, there are contraindications for an epidural especially for vaginal delivery, such as an emergency caesarean section. Because with an emergency C-section everything has to go much faster, therefore one chooses here a general anesthesia.
The disadvantages of an epidural for vaginal delivery must also be considered. The duration of birth can be prolonged by an epidural. In addition, complications with epidural puncture occur more frequently in pregnant women.
This can lead to a severe drop in blood pressure, which in turn leads to a reduced blood supply to the uterus and can therefore be dangerous for the child.
- Coagulation disorders
- Allergies to the local anesthetics
- Inflammations at the puncture site
- System Infections
- Shock conditions like lack of fluid
- Suspicion of increased cerebral pressure
- Changes in the spinal column such as ossifications and adhesions
- CNS diseases
In a planned caesarean section, pain transmission is normally blocked by an epidural from the 4th thoracic vertebra to the 4th sacral vertebra. Approximately 18 ml of 0.5% bupicaine or 0.75% rupivacaine is used for this purpose.
This eliminates the sensation of pain and temperature as well as the motor function of the muscles. The muscles of the abdominal wall for the Caesarean section are therefore completely slackened. High concentrations of anaesthetics are not allowed.
For more targeted pain reduction, the use of additional sufentanil is also possible. When administering the drugs, care must be taken to ensure that the deep sacral segments are also reached. For this purpose, the doctor usually gives the first half of the dose to the sitting pregnant woman.
The patient should then remain seated for about 5-10 minutes. This allows the local anesthetics to sink better into the deep sacral segments. First of all, it can be said that the trend towards spinal anaesthesia with planned caesarean section has increased in recent years.
In principle, one aims for the same heights of nerve blocks as with the PDA. In this case, local anesthetics are approx. 2.5-3ml of 0.5% bupivacaine.
The disadvantage here can be a faster drop in blood pressure when applied directly into the spinal canal. To prevent this drop in blood pressure, approx. 1000ml electrolyte infusion is administered during the spinal anaesthesia.
In addition, the drug Akrinor can be used to quickly get the drop in blood pressure under control. Again, there are complications and disadvantages for the pregnant woman. Spinal anaesthesia can be the most common symptom after spinal puncture – post-spinal headache. A further point is the danger of a rapid drop in blood pressure, which is more likely to occur with spinal anaesthesia than with PDA.Other very rare complications are cranial nerve disorders, spinal cord injuries (usually the puncture is placed under the spinal cord, so that a spinal cord injury is practically impossible! ), excessive spinal anaesthesia (when the anaesthetic flows up the spinal canal too far), bruising and infections of the region.
