Spinal or subarachnoid anesthesia
• It is a local anesthesia method also called subarachnoid and intrathecal block.
• Subarachnoid block is applied from L2-3 and lower levels from the distal medulla spinalis, which ends in the form of conus medullaris at the level of Ll-2 disc.
• Local anesthetic given to the subarachnoid space creates a reversible blockade.
• Anterior and posterior roots, posterior root ganglia are blocked by moving from distal to proximal.
• First the autonomic nerves, then the senses of heat, pain and touch disappear.
• This is followed by somatic motor block and profound sensory loss.
• Autonomic block of analgesia spreading to 2 or more dermatomes of the skin is seen.
• Motor block occurs 2-3 segments distal to the analgesia level.
• Local anesthetics are isobaric if the specific gravity is equal to CSF, hypobaric if it is lower than CSF, and hyperbaric if it is higher.
• Hyperbaric bupivacaine and tetracaine are the most commonly used agents in spinal anesthesia.
Factors affecting dermatomal spread of spinal anesthesia
The most important factors
Baricity of the anesthetic solution
patient's position
- During injection
- Immediately after injection
drug dose
injection site
Other Factors
Age
cerebrospinal fluid
inclination of the vertebral column
Drug volume
Intraabdominal pressure
direction of the needle
Patient's height
Pregnancy
Indications for Spinal Anesthesia
For interventions in the lower extremities, lower abdomen and perineum and for analgesia
It is used in cesarean and vaginal delivery.
Contraindications for Spinal Anesthesia
Hypovolemia, dehydration, hypotension, septicemia, infection at the site of intervention, increased intracranial pressure syndrome, coronary artery disease, patients with heart valve lesions, degenerative diseases of the spinal cord and nervous system (multiple sclerosis, amyotrophic lateral sclerosis, etc.), systemic with neurological sequelae diseases (pernicious anemia, porphyria, neurosyphilis), bleeding diathesis
Headache, back, low back pain, disc herniation, arthritis, spinal deformity, respiratory system disease, abdominal distention, full-blown patients, stressed, psychotic patients and being a child are relative contraindications.
Spinal anesthesia complications
Due to sympathetic blockade in the cardiovascular system, total peripheral resistance decreases, systolic and diastolic blood pressure decreases (HYPOTENSION).
After the block at T1-4 level, bradycardia and coronary perfusion disorder occur.
Treatment IV. fluids, vasoconstrictors are administered.
Nausea, vomiting may occur.
Back and low back pain may develop as a result of relaxation caused by a puncture in the waist or a block in the muscles.
Urinary retention may occur with S2-4 block.
Due to the splanchnic sympathetic block in the gastrointestinal tract, contractions in the intestines and relaxation of the sphincters occur.
As a result of T5 block, the endocrine response to surgery is eliminated.
Infection may occur if the rules of asepsis and antisepsis are not followed.
The most important late complication is headache.
o It is usually seen in the first 3 days.
o It occurs as a result of CSF loss and meningeal irritation.
o It is more common in young people, women and pregnant women when blocking with a thick needle.
o It is usually widespread in the frontal, sometimes occipital, and increases with standing.
Chronic adhesive arachnoiditis is the most important neurological complication.
Perianal loss of sensation, motor loss in lower extremities, bowel and bladder dysfunction.
N. abducens paralysis is also a rare and reversible complication.
Epidural Anesthesia
• Blocking the spinal nerves in the epidural space as they exit the dura and reach the intervertebral foramen is an epidural block.
• There are cervical, thoracic, caudal and epidural blocks according to the application site.
• Sensory and sympathetic fibers are completely blocked.
• Motor block occurs almost completely.
• The epidural space is a potential space. It is located between the dura mater and the periosteum that lines the vertebral canal. The widest part of the epidural space is in the lumbar region. This range includes dural sheaths, spinal nerves, adipose tissue, loose areolar tissue, vessels, and lymphatics. The veins are in the form of a venous network. Negative pressure is present in the epidural space in 80% of patients.
• Local anesthetic given to this space spreads from the dura to the CSF by diffusion from the dura in the intervertebral foramen region and to the anterior and posterior roots, ganglia and other nerves in the paravertebral area.
• The epidural block is made at the level of the intervention area. In addition, the level of anesthesia is adjusted with the appropriate position and local anesthetic density. 2-2.5 ml of local anesthetic is given per segment to be blocked. For patients over 40 years of age, the dose is reduced by 0.1 ml per 10 years.
• It is understood that the epidural space is entered with the loss of resistance that occurs when passing the rigid ligamentum flavum while performing the epidural block. In addition, if the needle is advanced with an air-filled syringe, air will be sucked in the epidural space. Furthermore, while the needle is in the interspinous ligament, a drop of saline or distilled water is suspended on its tip and slowly advanced. Once it enters the epidural space, the drop will be drawn in with negative pressure.
• Epidural block can be administered as a single-dose injection or as a continuous block with a catheter.
Epidural anesthesia indications
• Surgical interventions
• Epidural anesthesia; It can be used in conjunction with superficial anesthesia in pelvis, lower abdomen, lower extremity surgeries and postoperative analgesia, when general and spinal anesthesia is contraindicated. It is especially preferred in those with poor general condition, lung disease and metabolic disorders.
• Obstetric interventions
• Epidural anesthesia can be used in the prevention and treatment of hypertension in vaginal delivery, cesarean section anesthesia, pre-eclampsia and eclampsia.
• It is used for postoperative pain relief, chronic and persistent pain, mesenteric thrombosis, acute pancreatitis, dissecting aortic aneurysm, visceral pain treatment and spasm resolution in peripheral vascular disease.
Epidural anesthesia contraindications
• Systemic and local infection, bleeding, shock, anticoagulant therapy, bleeding diathesis, central nervous system disease and local anesthetic sensitivity are contraindications.
• Relative contraindications are vertebral column deformity, arthritis, osteoporosis, previous laminectomy, cardiovascular system disease, hypertension, hypotension and intestinal obstruction.
Complications of epidural anesthesia
• Since there is no loss of CSF in epidural block, headache is not seen.
• Hypotension is much less frequent and severe than spinal anesthesia.
• The neuroendocrine response to stress is prevented by epidural anesthesia.
• Adrenocortical and sympathetic response is prevented by spinal afferent system block that causes this response.
• High epidural block prevents coughing.
• Headache, dizziness, bradycardia, increased blood pressure, convulsions may occur during rapid injection. If the dura is accidentally punctured and a high dose of local anesthetic is given, total spinal block may develop.
• Hypothermia may develop due to vasodilation.
Caudal (Sacral Epidural) Block
• It is applied in perianal, urethral, perineal and lower extremity interventions.
• It is used for treatment of low back and sciatic nerve pain, pain of vasospastic diseases in the legs and postoperative pain.
Neuraxial blockade contraindications
