SPINAL ANESTHESIA

SPINAL ANESTHESIA Local anesthestic deposited at subarachnoid space Sub Arachnoid Block, 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

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

Contraindications Absolute Relative 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

Drugs Used Factors Determining Level of Anesthesia 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

Technique Interspaces between L2-L3, L3-:4, L4-L5 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

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

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

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

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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