2. Introduction
The spinal,epidural and caudal blocks are collectively known as
NEURAXIAL BLOCK
Each of these blocks can be performed as a single injection or
with a catheter to allow intermittent boluses or continuous
infusion.
These blocks result in sympathetic block, sensory analgesia and
motor block depending upon the dose, concentration and
volume of local anaesthetic
3. Advantages of Regional
Anaesthesia over GA
• Safe, reliable technique in patients at risk of apnoea,
bradycardia, desaturation, cardiac or respiratory complications
after GA.
• Good alternative for day care surgeries.
• Minimal risk of postoperative respiratory depression.
• Limited stress response to surgery,
• Cost effective.
4. CONTRAINDICATIONS
Absolute
Patient Refusal
Infection At The Site Of Injection
Coagulopathy And Other Bleeding
Disorders-Severe
Hypovolemia
Increased Intracranial Pressure
Severe Aortic Stenosis
Severe Mitral Stenosis
Relative
Sepsis
Uncoperative Patient
Preexisting Neurological Deficits
Severe Spinal Deformity
Controversial
Prior Surgery At The Site Of Injection
Complicated Surgery
Prolonged Operation
Major Blood Loss
5. Spinal and epidural anatomy
• The spinal cord terminates at L1 in adults and at L3 in infants.
• The line joining the iliac crests (intercristine or tuffer’s line) is at L4 level.
• C7 is the most prominent spinous process; T7 is at the inferior angle of
the scapula level.
• The subarachnoid space ends at S2 in adults, and is lower in children.
• The subarachnoid space extends laterally along the nerve roots to the
dorsal root ganglia.
• The subdural space is a potential space between the dura and the
arachnoid.
• The epidural (extradural) space lies between the walls of the vertebral
canal and the spinal dura mater. It is a low-pressure space, occupied by
areolar tissue, loose fat and the internal vertebral venous plexus.
• The ligamentum flavum is thin in the cervical region, reaching maximal
thickness in the lumbar region (2–5mm)
7. Anatomic Approach
Midline Approach
• Skin
• Subcutaneous tissue
• Supraspinous ligament
• Interspinous ligament
• Ligamentum flavum: Thickness about 1cm in the middle
• Epidural space: Contains fat and blood vessels
• Dura mater: When the dura is pierced one will appreciate a
“give” or change in resistance.
• Arachnoid mater space:This contains the spinal cord and
nerve roots
Paramedian or Lateral Approach
• Same as midline
excluding supraspinous
&
interspinous ligaments
8. Indications for Spinal Anaesthesia
Site of surgery:
• Obstetric Anaesthesia.
• Orthopaedic procedures of the
lower limbs
• General surgery procedures such
as inguinal hernia repair
• Gynaeco- logical: e.g. surgery to
perineum or genitalia.
• Urological operations
Patient Factors:
• Systemic disease such as chronic
respiratory disease, hepatic,
renal disorders.
• Geriatric patients.
• Patients with aspiration risk e.g.
hiatus hernia, diabetes mellitus
• Difficult intubation risk.
9. Practical Preparation of a Patient for Spinal
Anaesthesia
• Pre-operative visit.
• Theatre Preparation: Theatre Equipment such as the Boyle’s Machine, ECG, O2
saturation and NIBP
• Emergency drugs must be prepared.
• Emergency trolley.
• Co-loading with Intravenous Fluid: 1L MRL
• Positioning the Patient for Lumbar Puncture: Sitting, lateral, Prone(anorectal
procedure, jack)
10. Local anaesthetic drugs and doses for spinal anaesthesia
• Bupivacaine 0.5% is usually used. ‘heavy’ is hyperbaric and contains 8%
glucose.
• A volume of 2.5–3.0mL of a hyperbaric solution of LA will reach
t6–t10 in most non-pregnant young adults placed in the recumbent
position shortly after spinal injection.
• Pregnant patients require less, often 1.8–2.2mL
• Lidocaine is associated with a risk of cauda equina syndrome, transient
radicular irritation and transient neurological symptoms
• Opioids are often added to improve the quality of the block
Morphine 0.1–0.2mg
Diamorphine 0.25-0.5mg
Fentanyl 10–25 mcg
pethidine 10–25mg
11. PHYSIOLOGICAL EFFECTS OF SPINAL
ANAESTHESIA
CARDIOVASCULAR SYSTEM
• combined α+β blocking effect on heart
• Venodilatation and fall in venous return lead to low cardiac output and
hypotension during onset(Bain-bridge reflex)
• Decreased stroke volume and heart rate due to blockade of peripheral
(T1-L2) and cardiac (T1-T4) fibres.
• Cardiac output shows a biphasic response i.e. early transient increase
followed by eventual decrease. (Initial increase is due to greater decline in
SVR than the venous return)
12. • Block of cardio acclerator sympathetic fibers from T1-T4 leads to
subsequent bradycardia
• Extensive peripheral sympathectomy(T5-L2) also leads to
bradycardia and pooling in lower extremities
• Hypotension triggers compensatory baroreceptor response leading
to vasoconstriction and tachycardia above block level, reduction in
venous return/RA filling which decreases signal output of intrinsic
chronotropic receptors of RA leading to increase in parasympathetic
tone.
• BEZOLD JARISCH REFLEX- Bradycardia and subsequent
cardiac arrest due to profound hypotension via activation of 5HT3
mediated receptors of vagus and the ventricular myocardium.
13. GASTROINTESTINAL FUNCTIONS
• Nausea and vomiting due to GI hyperperistalsis due to
unopposed vagal activity. Contracted bowel and relaxed
sphincters due to sympathetic blockade.
• Bladder and urogenital dysfunction
• Colonic blood supply and oxygen availability is increased.
14. RESPIRATORY SYSTEM
• High spinal may cause paralysis of intercostal muscles,
diaphragm and accessory respiratory muscles.
• Cautiously given in patients with limited respiratory
reserve
• Tidal volume remain unchanged.
• Vital capacity decreases minimally d/t loss of abdominal
muscle contribution in forced expiration
• Apnea due to hypotension which causes medullary
ischemia in high/total spinal cases
16. Spinal anesthesia in pregnancy
Decreased dose requirement due to:
• Mechanical factor : compression of IVC causes shunting of
blood to the venous plexus in the vertebral canal leading to
decreased vertebral canal space and CSF volume
• Hormonal factor – higher progesterone levels
19. Post dural punture headache
• Due to leak of CSF from dural defect leads to traction in
supporting structure especially in dura
• Postural in nature increase in sitting and relieved in lying down
position. Most PDPHs develop 24 to 72 hours after dural puncture.
• Occur in frontal or occipital region, pain and stiffness in neck may
be present. Headache may last days, weeks or months but usually 1-
2weeks
20. TREATMENT
PROPHYLACTIC:-
• Smaller the needle gauge, lower the incidences of headache.
• Needle point having pencil point tip as in Whitaker type has lower
incidences of PDPH.
• Orienting needle bevel parallel with axis of spine.
• Maintain hydration and Early ambulation
TREATMENT OF ESTABLISHED CASES OF PDPH
• Simple analgesics(NSAIDS)and Bed rest
21. HIGH SPINAL ANAESTHESIA
• As the level of sensory anaesthesia ascends ,there is hypotension, aphonia
altered sensorium profound bradycardia and respiratory insufficiency
occurs due to blockage of cervical nerve roots.
• TREATMENT
Support airway and circulation.
Supplemental oxygen along with assisted ventilation may be required.
Decrease in BP and HR should be treated by I.v fluids , vasopressors and/or
atropine
22. CARDIAC ARREST
• If the block progresses (High Spinal) to the mid thoracic
region involving the heart.
• Usually due to hypoxaemia <85% without obvious changes in
respiration and cyanosis.
• Use of fentanyl, can account for bradycardia and arrest
• Incidence is commoner in young healthy adults, preceded by
bradycardia.
Treatment-conventional doses of atropine and ephedrine is
given
• Full resuscitation dose of epinephrine is given
23. EPIDURAL ANAESTHESIA.
• DEFINITION: It’s an anaesthesia technique obtained by blocking
spinal nerves in the epidural space,as the nerves emerges from the
dura and then passes through the intervertebral foramina
24. LOCAL ANAESTHETIC SOLUTIONS FOR
EPIDURAL BLOCK
• Lignocaine:- 1-2%,it has rapid onset in about 10 minutes and gives good
relaxation , duration of effect is 1-2 hr. Lignocaine and bupivacaine can be given in
mixture.
• Bupivacaine:-long acting ,used in 0.5% concentration ,give analgesia for up to
8hrs.
• Prilocaine:-less toxic than lignocaine ,doses in excess of 600mg may cause
cyanosis from methahemoglobinamia.
• Ropivacaine:- 0.25 -1%
• Chloroprocaine:-short latency and duration of action(about 45mins),its effect
ceases suddenly.
• Epinephrine is frequently added to local anaesthetic solution in order to increase
the depth of blockade and significantly prolong
• the duration of anaesthesia.
25. ADJUVANTS TO EPIDURAL BLOCK
• Sodium bicarbonate(with lidocaine)
• Epinephrine , clonidine and dexmedetomidine.
• Clonidine and dexmedetomidine (intensify and prolongs the effect
also provide postoperative analgesia)
• Sedation is common
Opioids – fentanyl ,sufentanyl and morphine
26. OMBINED SPINAL- EPIDURAL ANESTHESIA
• Combined spinal-epidural anesthesia is a technique in which a spinal
anesthesia and epidural catheter are placed concurrently.
• This approach combines the rapid onset and intense sensory
anesthesia of a spinal anesthesia with ablity to supplement and
extend the duration of block afforded by an epidural catheter.
• Also to provide post operative analgesia after procedure
• Needle through Needle technique most common
• Performed at L3-L4/L4-L5 interspaces.(conus upto L2/L3)
• After identifying the epidural space with the usual LOR technique
insert a long small guage spinal needle through the epidural needle, a
pop up felt as dura is entered.
• Stablize both needles, withdraw stylet, look for CSF and inject the SAB
drug
• Withdraw the spinal needle and insert epidural catheter
