Sacral horns, at the top of the interyagal fold, easy to grope on a thin patient. The sacrococcygeal membrane forms a soft “valley” between and just below these “mountains”.
Sacrum | Lat., Eng. sacrum; ukr Krizh ] is a sphenoid bone, formed by spliced five sacral vertebrae, connected cranially with the fifth lumbar vertebra, and caudally with the tailbone [Lat. os coccygis; English coccyx; ukr / suprica], the tip of which is an important guide for caudal anesthesia.
Sacral canal [lat. canalis sacralis; ukr curved canal ] —the extension of the lumbar spinal canal — is terminated caudally to the opening of the sacral canal [lat. hiatus sacralis; ukr po3meip croissants \ covered with a dorsal sacrococcygeal ligament [Lat. ligamentum sacrococcygeum dorsale; ukr Dorsal Krizhova-Kuprikov link ]. Anesthesiologists call it shorter: Sacrococcygeal membrane | Eng. sacrococcy geal membrane ]. Precisely her they pierce with caudal anesthesia.
Hiatus sacralis — the gap between the unintegrated bow of the fifth sacral vertebra — has a different form in different people. As a rule, this is the shape of the letter L or an inverted letter U (Fig. 114). But both the shape and size of this hole have many options. Thus, in almost 1% of adults, complete sacral spina bifida is possible , that is, the back wall of the cross channel has a shelf throughout its length , however, this does not prevent the execution of caudal anesthesia. The other extreme is the complete absence of hiatus sacralis. (ossification of the cruciate-kopikov membrane) makes it impossible to caudal anesthesia. In 5% of adults, the distance between the anterior and posterior walls of the sacral canal at the level of the sacral opening does not exceed 2 mm, then it will also be difficult to insert a needle into it.
Sacral horns [Latin cornua sacralia \, protruding from both sides of hiatus sacralis , are important landmarks for its search (Fig. 114). Unfortunately, sometimes in obese adults it is impossible to grope them. It is easier to do this either with the back of the middle phalanges of the fingers, or with the tips of the relaxed fingers of the left hand, pressed against the fingers of the right hand.
The dural sac ends at the level of the back openings 52 (at the level of the line connecting both spinae iliacaeposteriores superiores), the distance between it and the top of the hiatus sacralis in most adults is 4 cm, although it is often only 2 cm. the tip of the needle should not be administered to adults — more than 2 cm, and children — more than I, so as not to pierce the dura mater.
The epidural space in the sacral canal has a much larger volume than at other levels (since the dural sac is already ending here), and therefore the segmented dose of local anesthetics would be twice as large. In addition, this volume is very different from different people. Thus, the volume of the sacral canal (in the dried sacral bones) in adults is from 12 to 65 ml. Therefore, it is almost impossible to calculate the exact doses of local anesthetics. Unlike other levels, the fact of its communication with presacral connective tissue is proved for sacral epidural space, that is, with caudal anesthesia, a solution of local anesthetic freely flows through the anterior paired holes of the sacrum, which also explains the need for large volumes. Through the epidural space of the sacral canal, five pairs of sacral and one pair of spinal roots of the spinal cord are covered with a dura mater, which are blocked by an injected caudal local anesthetic.
The epidural veins in the sacral canal are as abundant as in other departments, and the higher they are, the more abundant. It is also a reason not to insert the needle too far beyond the sacrococcygeal membrane.
Adipose connective tissue of the sacral epidural space in adults is relatively dense and can have many bridges (which explains the unpredictability of caudal anesthesia in adults), and in young children it is so loose that, with caudal anesthesia, the block is safer and more evenly and can hold the catheter even to the thoracic.