Neuraxial anaesthesia

1. NEURAXIAL
ANAESTHESIA

2. Neuraxial Anesthesia
• Neuraxial anesthesia is a type of regional
anesthesia that involves injection ofanesthetic
medication in the fatty tissue that surround
the nerve roots as they exist the spine (also
known as an epidural and caudal) or into the
cerebrospinal fluid which surrounds the spinal
cord (also known as aspinal).

3. HISTORY
• 1885 - J.Leonard Corning – first spinal anesthetic
was administered accidentally Theneedle wasmade
of gold
• 1898 -August Bier - first planned spinalanesthesia
for surgery
• In 1921, Spanishmilitary surgeon Fidel Pagés(1886–
1923) developed the modern technique of lumbar
epidural anesthesia

4. Advantages of Regional Anesthesia overGA
Safe, reliable technique in patients at risk of apnoea,
bradycardia, desaturation, cardiac or respiratory
complications afterGA
Good alternative for day caresurgeries
Minimal risk of postoperative respiratorydepression
Limited stress response tosurgery
Cost effective

5. Spinal anesthesia
Spinal anesthesia involves the use of small amounts of local
anesthetic injected into the subarachnoid space to produce
a reversible loss of sensation and motor function. The
anesthesia provider places the needle below L2in the adult
patient to avoid trauma to the spinal cord. Spinalanesthesia
provides excellentoperating conditions for
– Hernia (Inguinal or epigastric).
– Haemorrhoidectomy , fistula ,fissure.
– cystectoscopy
– Transurethral resection of the prostate and transurethral resection of the
bladder tumors.
– Abdominal and vaginal hysterectomies
– Caesareansections.
– Lower limb surgery(orthopedic,plastic,vascular)

6. Vertebral Anatomy
• Eachvertebra consists of apedicle, transverse
process, superior and inferior articular processes,
and aspinous process.
• Eachvertebra is connected to the nextby
intervertebral disks.
• There are 2 superior and inferior articular processes
(synovial joints) on each vertebra that allows for
articulation.
• Pedicles contain anotch superiorly and inferiorly to
allow the spinal nerve root to exit the vertebral
column.

7. VERTEBRA
33Vertebrae
◦ 7 Cervical
◦ 12Thoracic
◦ 5 Lumbar
◦ 5 Sacral
◦ 4Coccygeal

8. Vertebral Anatomy- TopView
T
ransverse
Process
V
ertebral
Body
SpinalCanal
Spinous
Process
Lamina

9. Ligaments that support thevertebral
column
Ventral side:
Anterior and
posterior
longitudinal
ligaments
Dorsalside:
Important
since these
are the
structures
your needle
will pass
through!

10. Spinal Cord
• Spinal Cord
– Adult
• Begins: Foramen Magnum
• Ends:L1
– Newborn
• Begins: Foramen Magnum
• Ends:L3
– Terminal End:Conus Medullaris
– Filum Terminale:Anchors in sacralregion
– CaudaEquina: Nerve group of lower dural sac

11. Termination of SpinalCord
In adults usually ends at L1.
Infants L3
There are anatomical
variations. For most adults it is
generally safeto place aspinal
needle below L2unless there is
aknown anatomic variation.

12. Sagittal Section Through LumberVertebrae
Supraspinous
Ligament
(Outer most layer)
Intraspinous Ligament
(Middle layer)
Ligamentum Flavum
(Inner most layer)

13. CSF
• Clear fluid that fills the subarachnoidspace
• Total volume in adults is 100-150ml
• Volume found in the subarachnoid spaceis25-35
ml
• Continually produced at arate of450 ml per 24
hour period replacing itself 3-4times
• Reabsorbed into the blood stream byarachnoid
villi andgranulations
• Specific gravity is between 1.003-1.009 (this will
play acrucial role in the baracity of local
anesthetic that onechooses)

14. Membranes that surround the spinalcord
• Piamater- highly vascular,covers the spinal cord and
brain
• Arachnoid mater- non vascular and attached to the
dura mater. Principal barrier to the migration of
medications in and out of theCSF
• Dura mater (“tough mother”)- extension ofthe
cranial dura mater, extends from the foramen
magnum to S2(ending at the filum terminale)

15. Adapted with permission from “Unintended subdural injection: a complication of epidural anesthesia- a case report”, AANA Journal, vol. 74, no. 3, 2006.

16. CONTRAINDICATIONS
Absolute
Patient Refusal
Infection At TheSite Of Injection
Coagulopathy And Other BleedingDisorders
SevereHypovolemia
Increased Intracranial Pressure
SevereAortic Stenosis
SevereMitral Stenosis

17. CONTRAINDICATIONS
Relative
Sepsis
Uncoperative Patient
Preexisting Neurological Deficits
SevereSpinal Deformity
Controversial
Prior SurgeryAt TheSite Of Injection
Complicated Surgery
ProlongedOperation
Major BloodLoss

18. Spinal Technique
• Preparation & Monitoring
– EKG
– NBP
– PulseOximeter
• Patient Positioning
– Lateral decubitous
– Sitting
– Prone (hypobaric technique)

20. PATIENTPOSITIONING
• SITTINGPOSITION

21. PATIENTPOSITIONING
• LA
TERALDECUBITUS

22. Positions for SpinalTap
Procedures

24. • Midline Approach
– Skin
– Subcutaneoustissue
– Supraspinous ligament
– Interspinous ligament
– Ligamentum flavum
– Epidural space
– Dura mater
– Arachnoid mater
• Paramedian or LateralApproach
– Sameasmidline excluding supraspinous &
interspinous ligaments
Anatomic Approach

25. Spinal Anesthesia Levels

26. Complications of SpinalAnaesthesia
• Hypotension
• Bradycardia
• Total SpinalAnesthesia
• Neurological Complecations – CaudaEquina
Syndrome
• PostDural Puncture Headache
• Infection
• Backache

27. Spinal Pharmacology
Factors Effecting Distribution
Site of injection
Shape of spinal column
Patient height
Angulation of needle
Volume of CSF
Characteristics of local anesthetic
Density
Specific gravity
Baracity
Dose
Volume
Patient position (during & after)

28. Spinal Pharmacology
Anesthesia level is determined by patient position
Uptake of local anesthetic occurs by diffusion
Elimination determines duration of block
Lipid solubility decreases vascular absorption
Vasoconstriction can decrease rate of elimination

29. Cardiovascular Effects
Blockade of Sympathetic Preganglionic Neurons
Send signals to both arteries and veins
Predominant action is venodilation
Reduces:
Venous return
Stroke volume
Cardiac output
Blood pressure
T1-T4 Blockade
Causes unopposed vagal stimulation
Bradycardia
Associated with decrease venous return & cardioaccelerator fibers
blockade
Decreased venous return to right atrium causes decreased stretch
receptor response

30. Hypotension
Treatment
Best way to treat is physiologic not pharmacologic
Primary Treatment
Increase the cardiac preload
Large IV fluid bolus within 30 minutes prior to spinal placement, minimum
1 liter of crystalloids
Secondary Treatment
Pharmacologic
Ephedrine is more effective than Phenylephrine

31. Respiratory System
Healthy Patients
Appropriate spinal blockade has little effect on ventilation
High Spinal
Decrease functional residual capacity (FRC)
Paralysis of abdominal muscles
Intercostal muscle paralysis interferes with coughing and clearing
secretions
Apnea is due to hypoperfusion of respiratory center

32. EPIDURALANESTHESIA

33. Introduction:
• Epidural anesthesia is acentral neuraxialblock
technique with manyapplications.
• Theepidural spacewasfirst described by Corning in
1901, and Fidel Pagesfirst used epidural anaesthesiain
humans in 1921.
• In 1945 Tuohyintroduced the needle which is stillmost
commonly used for epiduralanesthesia.
• it can be used asan anesthetic, asan analgesic
adjuvant to general anesthesia, and forpostoperative
analgesia in procedures involving the lower limbs,
perineum, pelvis, abdomen andthorax.

34. Indications:
• Epidural anaesthesia canbe used assole anaesthetic for
procedures involving the lower limbs, pelvis, perineum
and lower abdomen.
• It is possible to perform upper abdominal and thoracic
procedures under epidural anaesthesia alone, but the
height of block required, with its attendant side effects,
make it difficult to avoid significant patient discomfort
and risk.
• Theadvantage of epidural over spinal anaesthesia isthe
ability to maintain continuous anaesthesia after
placement of an epidural catheter, thus making it
suitable for procedures of longduration.

37. Technique of Epidural Anesthesia
 Loss of resistance technique to identify the epidural
space.
– 0.5% Bupivacaine (mainly) or lidocaine (2.0%) is
usually used to produce epidural anaesthesia.
– Local anaesthetic solutions are deposited in the
epidural space between the dura mater and the
periosteum lining the vertebral canal.
– The epidural space contains adipose tissue,
lymphatics and blood vessels.
– The injected local anaesthetic solution produces
analgesia by blocking conduction at the spinal
nerve roots.
32

38. 33

39. Indication and Contraindication:
• The same of spinal anaesthesia.
• Additional indication is the post operative Pain
management using the epidural catheter
technique.
• Complications: the same of spinal anaesthesia,
except the postdural puncture headache.
35

40. Detail Technique of Epidural
Anaesthesia
• Usinglocal anaesthetic raise asubcutaneous wheal at the midpoint
between two adjacentvertebrae.
• Inflitrate deeper in the midline and paraspinously toanaesthetise the
posterior structures.
• Insert epidural needle to the skin at this point,and advance through
the supraspinous ligament, with the needle pointing in aslightly
cephalad (upward) direction.
• Then advance the needle into the interspinous ligament, whichis
encountered at adepth of 2-3cm Until distinct sensation of
increased resistance is felt astheneedle passesinto the
ligamentum flavum.

41. With 5-10ml of air in the syringe, attach it to the hub of the needle once it
hasentered the interspinous ligament.
Theplunger is gently pressed,and if there is resistance ("bounce"), the
needle is very carefully advanced, with the dorsum of both hands resting
against the back to providestability.
After 2-3mm, the plunger is again gently pressed,and thisprocedure is
repeated asthe needle is carefully advancedthrough thetissues.
Thedistinctive decreasein resistance when the needle entersthe
ligamentum flavum is felt, and theprocessis continued in 2mm increments.
There is usually a distinctive "click" when the needle enters the epidural
space, and provided great care is taken, and the needle only advanced in
2mm increments, the needle should stop before it reaches the dura.
At this point air can be injected into the epidural spacevery easily.The
syringe is removed and the catheterthreaded

42. • Removethe syringe and thread the catheter gently via theneedle
into the epiduralspace.
• Thecatheter hasmarkings showing the distance from its tip, and
should be advancedto 15-18cm at the hub of the needle, to ensure
that asufficient length of catheter hasentered the epiduralspace.
• Removethe needle carefully, ensuring that the catheter isnot
drawn back with it.
• The markings on the needle will show the depth of the needle from
the skin to the epidural space, and this distance will help determine
the depth to which the catheter should be inserted at the skin.
• For example, if the needle entered the epidural space at a depth of
5cm, the catheter should be withdrawn so that the 10cm mark is at
the skin, thus leaving approximately 5cm of the catheter inside the
epidural space,which is an appropriate length.

45. 34

46. Choice of drugs:
• Thechoice of drugs administered epidurally depends onthe
indication for theepidural:
• Surgical anaesthesia:Requires dense sensory block and usually
moderate to dense motor block. T
oachieve this, concentrated local
anaesthetic preparations are required. Themost commonly usedlocal
anaesthetics in this setting are 2% lignocaine 10-20ml (with or
without adrenaline 1:200 000) or 0.5% bupivacaine 10-20ml. The
latter hasalonger duration of action, but aslower onset time,
compared with lignocaine.
• For analgesia during labour: 0.1-0.25% bupivacaine 5-10ml ismore
popular, asit produces lessmotor block.
• Postoperative analgesia: weaker concentrations of bupivacaine, e.g.
0.1-0.166%with or without added lowdose opioids.

47. Differences between Spinal and Epidural Anesthesia
Spinal anaesthesia Epidural Anaesthesia
Level: below L1/L2, where the spinal cord ends Level: at any level of the vertebral column.
Injection: subarachnoid space i.e, puncture of the
dura mater
Injection: epidural space (between Ligamentum
flavum and dura mater) i.e ,without puncture of
the dura mater
Identification of the subarachnoid space: When
CSF appears
Identification of the epidural space: Using the
Loss of Resistance technique.
Doses: 2.5- 3.5 ml Bupivacaine 0.5% heavy Doses: 15- 20 ml Bupivacaine 0.5%
Onset of action: Rapid (2-5 min) Onset of action: Slow (15-20 min)
Density of block: More dense Density of block: Less dense
Hypotension: Rapid Hypotension: Slow
Headache: Is a probable complication Headache: Is not a probable complication. 41

48. Complications and SideEffects
• Hypotension
• Inadvertent high epiduralblock
• Local anaesthetictoxicity
• T
otalspinal block

49. CAUDALANESTHESIA

50. Introduction:
• Caudalanesthesia hasbeen used for many yearsandis
the easiest and safest approach to the epidural space.
When correctly performed there is little danger of
either the spinal cord ordura being damaged.
• It is used to provide peri and post operative analgesia
in adults andchildren.
• It may be the sole anesthetic for some procedures, or it
may be combined with generalanesthesia.

51. Indications:
1. Anesthesia and analgesia below theumbilicus
2. Obstetric analgesia :For the 2nd stageor
instrumental deliveries. Careshould be taken as
the foetal head lies close to the site of injection
and there is real risk of injectinglocal anesthetic
into the foetus.
3. Chronic pain problems relating to lowerlimbs
and lower abdominalpains.

52. Contraindications:
1. Infection near the site of theneedle
insertion.
2. Coagulopathy or anti coagulation.
3. Congenital abnormalities of the lowerspine
or meninges, becauseof the unclear or
impalpable anatomy.

53. Anatomy:
• Thecaudal epidural space
is the lowest portion ofthe
epidural space and is
entered through the sacral
hiatus.
• Thesacrum is atriangular
bone that consists of the
five fused sacralvertebrae
(S1-S5).
• It articulates with the fifth
lumber vertebra and the
coccyx.

54. • Thesacral hiatus is adefect
in the lower part of the
posterior wall of the sacrum
formed by the failure of the
laminae of S5and/or S4to
meet and fuse in themidline.
• Thesacral canal is a
continuation of the lumbar
spinal canal which terminates
at the sacralhiatus.

55. Choice of drugs &dosage:
• Drugs that are commonly usedinclude :
 Lignocaine 1%and
 Bupivacaine 0.25%.

56. Technique:
Thepatient is prepared as for generalanaesthesia:
(1)He/she should be fasted
(2)All appropriate equipment for resuscitation mustbe
available.
(3)An intravenous cannula should always be inserted in an
upper limb, in caseof accidental intravenous injection, or
profound sympathetic blockade from ahigh epiduralblock.
(4)The procedure must be carried out with a strict aseptic
technique. The skin should be thoroughly prepared and
sterile glovesworn.

57. (5) Thereare three mainapproaches:
• Theprone, the semi-prone, and the lateral. Thechoice
depends on the preference of the anesthetist and the
degree of sedation of the patient. Thecaudal spaceismade
more prominent by asking the patient to internally rotate
their ankles.
Thesemi-prone position is preferred for the anesthetised or
heavily sedated patient asthe airway is easier to control in
this position, while still allowing reasonably easyaccessto
the sacralhiatus.
Thelateral position is often used in children, asthe
landmarks are easier to find than in adults. Careshould be
taken to avoid over flexing the hips (asforlumber epidurals)
asthis can makethe landmarks more difficult to palpate

58. 6) Thelandmarks are
palpated. Thesacral hiatus
and the posterior superior
iliac spines form an
equilateral triangle pointing
inferiorly.
• Thesacral hiatus canbe
located by first palpating
the coccyx,and thensliding
the palpating finger in a
cephalad direction until a
depression in the skin is
felt.

60. 7) Oncethe sacral hiatus is
identified the areaabove
is carefully cleaned with
antiseptic solution, anda
22 gaugecannula or
needle is directed at
about 90 degree to skin
and inserted till a"click"
is felt asthe sacro-
coccygeal ligament is
pierced.

61. Careshould be taken not to insert the needle too far asthe
dura lies at orbelow the S2level in the child.
Theneedle should be aspirated looking for either CSFor
blood. Theinjection should never be more than 10ml/30
seconds
• Further tests to confirm the correct position include:
Introduction of asmall amount of air will not produce
subcutaneous emphysema, and will be heard asa"woosh"
sound if astethoscope is place further up the lumbarspine.
There should be no local pain during injection.

62. (9)Asmall amount of local anaesthetic should beinjected
asatest dose (2-4mls). It should not produce either a
lump in the subcutaneous tissues, or afeeling of
resistance to the injection, nor any systemic effects
such asarrhythmias or hypotension.
If the test dose does not produce any side effects then
the rest of the drug is injected, the needle removed and
the patient positioned for surgery. In the post-operative
period, motor function must be checkedand the
patient should not be allowed to try and walk until
complete return of motor function is assured. The
patient should not be discharged from hospital until
he/she haspassedurine, asurinary retention is a
recognized complication.

63. Complications:
Intravascular or intraosseous injection:Thismay lead to grandmal
seizuresand/or cardio-respiratory arrest.
Dural puncture: Extreme care must be taken to avoid this asatotal
spinal block will occur if the dose for acaudal block is injected into
the subarachnoid space. If this occurs then the patient will become
rapidly apnoeic and profoundly hypotensive.
Perforation of the rectum: Contamination of the needleis
extremely dangerous if it is then inserted into the epidural space.
Sepsis:This should be avery rare occurrence if strict aseptic
procedures are followed.
Urinary retention.
Haematoma