This document provides information on spinal anesthesia, including: - It involves injecting local anesthetic into the subarachnoid space to block spinal nerve roots and produce sympathetic block, sensory analgesia, and motor block. - It is used for surgery on the lower half of the body, abdomen, perineum, lower extremities, and vaginal/C-section deliveries. Contraindications include bleeding disorders and increased intracranial pressure. - Common drugs used are tetracaine, lidocaine, and bupivacaine. The level of anesthesia is determined by factors like volume, concentration, speed of injection, and patient position. Potential complications include hypotension, nausea

1. SPINAL ANESTHESIA

2. 1. Sub Arachnoid Block,
2. Intrathecal Block
 Local anesthestic deposited at subarachnoid
space
 Acts on spinal nerve roots, dorsal ganglia, not
on substance of spinal cord
 Redistributed via vascular absorption
 Produces sympathetic block, sensory analgesia
and motor block
SPINAL ANESTHESIA

3. Indications
 Surgery involving lower half of body
 Upper abdomen
 Lower abdomen
 Perineum
 Lower Extremity
 Obstetrics – vaginal delivery
Caesarian section
 Painful diagnostic and therapeutic procedures
below diaphragm

4. Contraindications
 Absolute
 Bleeding disorders
 Septicemia
 Inc. intracranial pressure
 Chronic dermatitis or infection near puncture site
 Pre-existing spinal cord disease
 Hypotension
 Patient refusal
 Systemic disease with neurologic sequelae
 Relative
 Hemorrhage
 Back problem due to muscle strain, arthritis
 Extremely tense / psychotics
 Respiratory disease

5. Drugs Used
 Tetracaine
 Lidocaine
 Bupivacaine
Factors Determining Level of Anesthesia
 volume of solution
 concentration
 barbotage
 speed of injection
 patient position
 specific gravity of solution
 site of injection
 height of patient
 increased intra-abdominal pressure

6. Technique
A. Position
 Lateral decubitus – knees flexed to chest
hin put down on chest (nose-to-knee)
 Sitting – when lateral approach is difficult (e.g.
obese patients)
B. Puncture Sites
 Interspaces between L2-L3, L3-:4, L4-L5
 Line joining highest points of iliac crests
crosses either body of L4 or interspace
between L3-L4

8. Structures Traversed By Spinal Needle
a. Skin
b. Subcutaneous Tissue
c. Supraspinous ligament
d. Interspinuous ligament
e. ligamentum flavum
f. Dura

9. PHYSIOLOGIC EFFECTS (Immediate Complications)
A. Cardiovascular
Sympathectomy  vasodilation   BP,  CR
B. Respiratory
Difficulty of breathing
Apnea (high level)
C. Gastrointestinal
Nausea / vomiting in 20%
DELAYED COMPLICATIONS
 Headache – leak of CSF
 Backache
 Urinary retention
 Paraplegia – hematoma

10. Levels of Spinal Anesthesia – Dermatomes Involved
1. Saddle Block – sensory loss involves lowers lumbar
and sacral segments.
Area that “sits on the saddle”.
2. Low Spinal – level of umbilicus (T10) lower
thoracic lumbars and sacrals.
3. Mid-Spinal – costal margin (T6) lower thoracic
lumbars and sacrals
4. High Spinal – nipple line (T4) thoracic segments
(T4 – T12) lumbars and sacrals

12. Epidural anathesia Spinal anathesia
Site of injection In the epidural space Subarachnoid space
Onset and duration Slow onset and continous duration
(use catheter)
Rapid onset and limited
duration
advantages Can be used in analgesia Not used
Needle
dose
Curved,longand blunt (touhy)
10_30ml
Small and sharp
1_4ml
space Any space usually lumber lumber
Quality of sensory
and motor nerve
block
less More liable
toxicity Hypotention gradual
total spinal +++
systemic toxicity +++
Sudden
+
+

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