Regional anesthesia can be divided into neuraxial blocks and peripheral nerve blocks. Neuraxial blocks include subarachnoid, epidural and caudal anesthesia. Neuraxial blocks have specific anatomy, indications, contraindications, safety precautions, equipment, and techniques that must be followed. The document outlines the key anatomical structures involved in neuraxial blocks, when they are indicated, potential risks, how to prepare the patient, types of needles used, and proper positioning and aseptic techniques.
3. Regional anesthesia can be divided into neuraxial
blocks and peripheral nerve blocks.
Neuraxial blocks include subarachnoid, epidural
and caudal anesthesia.
4. Neuraxial blocks
Anatomy:-
spinal cord is surrounded by 3 layers:-
Pia matter subarachnoid space
arachnoid matter subdural space
dura matter epidural space
bone.
in the cervical region, the most prominanat
spinous process is C7.
The spinal cord ends at the level of L1-L2,
while the dural sac usually ends at S2 vertebra.
5. The spinous processes of the cervical and
lumber spine are Horizontal, they are directed
caudally in the thoracic region. (1)
The intercrestal line (between both iliac crests)
usually crosses either body of L4 or L4-5 interspace.
This is called Tuffier’s line.
The inferior angle of the scapula is at the same
level of spinous process of T7
6.
7.
8.
9. Indications for neuroaxial block
Any surgeries below the umbilicus.
Surgeries above the umbilicus. (1)
It has many advantages both medically wise and
surgically wise and for postoperative pain control.
10. Contraindications of neuraxial blocks:-
absolute:-
lack of consent.
Coagulopathy and anticoagulation therapy.
Bacteremia and skin infection at the site
of injection.
Hypovolemia and shock.
Demyelinating CNS disease.
Severe aortic and mitral stenosis.
11. Relative :-
Minidose heparine, aspirin…..etc.
Prior spine surgery or back pain.
Respiratory failure, especially if high block is
required.
Increases intracranial tension
Some cardiac lesions.
12. How to prepare the patient:-
Informed consent.
History taking and physical examination.
Laboratory testing including CBC and
coagulation profile.
Premedicate and preload.
Safety issues:-
Monitors; ECG, NIBP, and pulse oximetry
Resuscitaion equipment; G.A. and an anesthesia
machine have to be available .
13. Needles:-
Needles differ according to their bevel.
Bevel may be blunt edge, or sharp edge. (1)
Short, medium or long length.
We have a tuohy needle, used for epidural.
14. Techniques:-
Positioning the patient: sitting, lateral or prone. (1)
Identification of the anatomic land marks. (2)
15. Asepsis: of the anesthesiologist and the patient. (1)
Infiltrations of local anesthetic.
Needle introduction:- either median
or paramedian, with the bevel facing lateral. (2)
(1)Therefore, when performing a lumber or cervical epidural block, the needle is directed nearly horizontally with slight cephaled angle, and a much more cephaled angle in the thoracic spaces
(1) may need light general anesthesia to abolish the unpleasant sensation arising for visceral manipulation from the afferent impulses transmitted by the vagus nerve.
Cardiac lesions like idiopathic hypertrophic subaortic stenosis and mild to moderate aortic and mitral stenosis., as patients cant tolerate the vasodilatation especially in high blocks as they have fixed cardiac output
If spinal block is done, there will be a sudden drop of intracranial pressure and leak which is harmful, on the other hand epidural block increases CSF pressure
To detect any contraindication and we have tp palpate the lumber spaces.
1 blunt edge theoretically offers less dural trauma, and less C.S.F. leak and less spinal headache.
Sitting is the easiest most suitable for morbidly obese
Lateral suitable for obstetric patient
prone : Patient lies prone with head slightly lower( jack knife), useful for anorecal surgery and uses hypobaric solutions. Difficult as C.S.F will not drip by gravity, but may be aspirated.
(2) We use skin marker
Sterilizing the patients starting form the interspace and proceed in a widening circles, if we use povidone iodine we have to wipe it completely to avoid transverse myelitis.
(2) We raise the skin wheal just below the upper spinous process, andf we advance the needle in slight chephaled direction passing just below and under the upper spinous process. Contact with the bone…superficial spine process, deep lamina if midline or pedicle if offline. Then talk about the sensattion and the loss of resistance after ligmantum
Paramedian is used in difficult cases kyphoscoliosis, we raise the wheel 2 cm lateral to the spinous process and the needle is directed 10 degrees toward the medline and advanced
In spinal we advance, feel the different ligmantes and aftre the puncture of the dura, there will be loss of resisntance, correct positioning is known by the free flow of C.S.F.. We inject the medication slowly 1 ml/5 sec.
In epidural the same , but we need to identify the space first, by loss of resistance technique, hanging drop