Execution of the finger block
The first step of anesthesia is always the education of the patient. The patient receives important information about the drugs and their possible side effects and a procedure is selected. After the selection of the active substance, the planned puncture site is disinfected.
The finger block consists of two puncture sites starting from the extensor side of the finger. The foot block requires five injections around the lower leg just above the ankle. The cannula is pierced into the skin and in the case of the finger block is first advanced to the nerve on the flexor side.
There the first depot of local anesthetic is injected and then the cannula is retracted to the extensor nerve. This is repeated on the other side of the finger. The foot block involves larger nerves, some of which are better protected.
For this reason, several injections must be made and each nerve must be anaesthetised separately. After a few minutes the finger or foot should become numb and feel no more pain. If areas do not become numb, another injection will be made. During longer operations, catheters can also be left in place so that the anesthesiologist can give additional local anesthetics during the procedure.
Duration of a finger block
The duration of a finger block or foot block depends on various factors. In principle, the anesthesiologist can extend the anesthesia at any time and therefore a rough time can always be given only after the last injection. Each local anaesthetic has a different duration of action and a different time span until the effect begins.
In some cases different anaesthetics are combined. Most local anaesthetics last for about two hours after the last injection. Individual differences also change the duration of effect.
What risks and side effects can occur?
Regional anaesthesia and thus also Oberst’s block anaesthesia is a procedure with relatively few side effects. Allergic reactions are possible locally.If injected into the nerve by mistake, and not next to it as is usually the case, nerve damage and discomfort can occur. In rare cases it can lead to a systemic, i.e. an allergic reaction affecting the whole body, up to allergic shock.
For this reason, a different procedure should be chosen in case of a known allergy to the local anesthetic. If the local anaesthetic enters the bloodstream unplanned, stronger side effects are possible. Nausea, dizziness, drowsiness and restlessness may occur.
In rare extreme cases, seizures and respiratory paralysis are possible. Local anesthetics also have an effect on the cardiovascular system. The strength of the heart and the frequency of strokes diminish and blood pressure may drop.
In some cases, cardiac dysrhythmia can develop and even lead to sudden heart failure. Since these side effects occur particularly in patients with decompensated cardiac insufficiency or conduction disorders, a different anesthesiological procedure should be used in these cases.