Getting into the vessel occurs most often due to the high vascularization of the sacral canal. Due to the patient’s posture (up to the pelvis) and the low pressure in these vessels, blood will not flow through the needle itself, and aspiration is important for caudal anesthesia. But it is not absolutely reliable either, since the walls of the vein, which the needle tip has hit, can fall off during aspiration, closing the needle section. The more important for caudal anesthesia is the test dose of a local anesthetic.
If, after extracting the mandrel and performing the aspiration, you received blood, you can move the needle half a centimeter forward, insert the mandrin into it (so that it does not thrombus) and wait 2-3 minutes (until
blood flow from the punctured vein will stop). Then — remove the man- drains, repeat the aspiration, and if there is no blood, — you can enter a test dose.
Getting into the bone marrow is possible quite rarely only if you pierce the anterior wall of the sacral canal, thinking that it is a very dense and calcified sacrococcygeal membrane. During the aspiration test, a bone marrow can be collected through a thick needle (it cannot be distinguished macroscopically from blood), but nothing can be obtained through a thin needle. Even a test dose may not give any signs immediately, and manifestations of intoxication may appear only a few minutes after the introduction of the full dose.
Puncture of the dural sac is possible in approximately 1% of cases and is manifested by the production of cerebrospinal fluid during aspiration. Then you can perform spinal anesthesia (if the operating position allows it). With an unrecognized puncture, a total spinal block is possible (see the section “PROBLEMS DURING THE SUPPORT OF THE EPI
CURRENT ANESTHESIA “) In addition, headaches are possible in the postoperative period, especially after puncture with a thick needle (see the section” LONG-TERM COMPLICATIONS OF THE EPIDURAL ANESTHYTE “). Prevention — Avoiding needle insertion that is too deep.
Puncture of the fetal head during labor anesthesia, including with the death of a child, has been repeatedly described in the literature of developed countries , which contributed to the decline in the popularity of caudal analgesia in obstetrics.
Arterial hypertension during rapid administration of the main dose, which is explained by the reaction to compression of the spinal cord or its roots, as a rule, passes quickly on its own. Prevention —slow administration of the primary dose.
Arterial hypotension is possible with a high level of anesthesia, both planned (if a large dose is intentionally administered or a catheter is carried out highly), and also with an unforeseen (especially after a quick introduction of the main dose). That is why caudal anesthesia should be prepared as any epidural — with reliable venous access, tonometer and resuscitation equipment.
Problems with catheterization of the epidural (sacral) space are less common with caudal access than with intervertebral. If the needle is correctly inserted, the catheter goes very easily. If the catheter encounters resistance at the beginning of the insertion, it may be thought that the needle tip is not in the sacral canal. In the case of caudal access, the catheter cannot be pulled out through the needle either (so as not to cut it off). Even the case of catheter cutting was described, when a correctly inserted needle was taken out after its insertion: in it, when a bone was released, a “hook” was formed, directed toward the lumen . A hard catheter can puncture the dura mater. The formation of a node on the catheter in the cross channel is also described, and the neurosurgeon performed an operation to remove the catheter .
MONITORING
Maintaining verbal communication with the patient – the simplest and, in some way, the most reliable method, With caudal anesthesia, as with any epidural, one must constantly monitor the pulse and blood pressure, especially after a large dose and with a high level of the block. But the most convenient and reliable will be the constant verbal contact with the patient, who will quickly feel both significant changes in blood pressure and manifestations of intoxication with a local anesthetic. Therefore, deep sedation with effective caudal anesthesia is undesirable.