First, local anesthesia can be divided into 2 forms:
- The surface anaesthesia and
- The infiltration anesthesia
In surface anaesthesia, an area of the mucous membrane is sprayed or brushed with the local anaesthetic. This results in a blockage of small nerve endings that lie on the surface. Lidocaine 2-4% and mepivacaine 2% are considered surface anaesthetics.
A special feature is the EMLA cream, which is a mixture of the local anaesthetics lidocaine and prilocaine. After the time of application the cream with the active substances penetrates the skin and blocks the nerve endings there. Emla Cream
Infiltration anaesthesia
During infiltration anesthesia, the active ingredient is now injected into the skin (intradermal), into the subcutaneous fatty tissue (subcutaneous) or into the muscle (intramuscular). The nerve endings are then blocked again. Infiltration anaesthetics include the following: Infiltration anaesthetics often include an additive with adrenaline so that the local anaesthetic remains local in the tissue for a longer period of time and is not distributed so quickly.
Examples for the application of local anesthetics would be a wound suture or a visit to the dentist.
- Mepivacaine 0.5-1%
- Bupivacaine 0.25-0.5% Bupivacaine
- Levobupivacaine 0.25%
- Lidocaine 0.5-1
- Prilocaine 0.5-1%.
What now plays a role in pregnancy is the different fat solubility of the drugs. Local anesthetics with high fat solubility could quickly pass through the placenta.
Besides it depends on how high the protein binding in the body of the local anaesthetics is: The lower the protein binding is, the easier it comes to the transfer of the local anaesthetics into the placenta and thus to the child. For these reasons, pregnant women prefer a local anesthetic with high protein binding and low fat solubility. In general, however, no harmful effects of local anesthetics on the unborn child have been found in studies; they are merely precautionary measures.
If, on the other hand, the local anesthetic is incorrectly applied to the vessel, the situation is quite different. If the local anesthetic is injected into the vessel, the risk of complications is much higher. As already mentioned, adrenaline is often added to local anesthetics.
This is also possible during pregnancy. However, one should try to choose the lowest possible dosage (1:200. 000).
However, an injection into the vessel should be avoided in any case. Injecting adrenaline into the vessel can cause a contraction of the uterine vessels, which supply the child with vital nutrients. In addition, two adrenaline derivatives should not be used during pregnancy.
These are norepinephrine and felypressin. The following local anesthetics can be used during pregnancy: Prilocaine and mepivacaine should be used with caution.
- Articain
- Bupivacaine
- Etidocaine
