0 Spinal Anaesthesia

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Spinal anaesthesia also called sub-arachnoid block (SAB)


Needles used :
  • Whitacre
  • Sprotte

These have pencil tip point end (therefore decrease post puncture headache)


Layers pierced :
  1. Skin
  2. Subcutaneus
  3. Supraspinous ligament
  4. Interspinous ligament
  5. Ligamentum flavum (loss of ressistance felt as it is pierced)
  6. Dura
  7. Arachnoid - subarachnoid space

Drugs :
  • Lignocaine (5%- heavy due to dextrose )
  • Tetracaine (0.5% in 5% dextrose)
  • Bupivacaine (0.5% in 8% dextrose)

Factors affecting height of anaesthesia :
  • Dose (most important)
  • Baricity of solution
  • Volume of drug
  • Position of patient
  • Age
  • Height
  • Pregnancy
  • Abdominal Tumors

Effects of Spinal Anaesthesia :
Blocks Sympathetic system at the concerned level (therefore Increases Parasympathetic)

Thus Hypotension with Tachycardia (Marey's law) (tachycardia because T1-T4 sympathetic is intact and so there is compensatory tachycardia)

But with High Spinal Block -- there is Hypotension with Bradycardia (as T1-T4 sympathetic also blocked)


Other points to remember :
  • Autonomic block is 2 segments higher than sensory.
  • Maximum breathing capacity and active exhalation decrease because of intercostal paralysis.
  • Respiration is severely affected only if C3,4,5 involved (i.e very high spinal block)
  • Nausea, Vomiting
  • Vasodialator , therefore heat loss - shivering (T/t - Pethidine)
  • Successful sign -- Flacid and engorged Penis (due to paralysis of  Nervi Ergentis )
  • Most Common Complication : Hypotension 
  • Management for this : Prophylaxis - Preloading 1 - 1.5 L Coloid
                                     Curative : Foot end elevation
                                                    Colloids , Vasopressor
                                     If Bradycardia - Atropine



Post Spinal Headache : (Usually Occipital)

1. Low - pressure headache because of leak of CSF
    Therefore structures in brain are dragged down.

2. Presents :

  • 24 - 48hrs
  • Mostly > 90% in 7-10days
  • Almost all by 3weeks
3. Prevention : Use pencil tip needle


4. Curative T/t :

  • IV fluids
  • Analgesics
  • Inject 25 - 50 ml NS in epidural space
  • BEST -- Inject 15 - 20 ml autologus blood in epidural space (blood patch)



Other Complications (of Spinal Anaesthesia)
  • Cauda equina syndrome
  • Paraplegia
  • 6th Nerve paralysis
  • 1 , 9 , 10 nerve involvement
  • Anterior spinal artery syndrome
  • Meningitis
  • Backache


Contraindications :

  • Raised ICT
  • Refusal of patient
  • Infection at local site
  • Bleeding diasthesis
  • Hypotension , hypovolemia
  • Spinal deformities
  • Hypertension



Saddle block anesthesia :

  • A form of spinal anesthesia that produces loss of sensation in the buttocks, perineum, and inner thighs.
  • If a patient is kept sitting for several minutes after the injection of a small volume of a hyperbaric solution of local anaesthetic, a classical "saddle block" affecting only the sacral nerve roots will result.




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