Subarachnoid block a brief insight .pptx

1
SUB ARACHNOID BLOCK
PRESENTATOR: DR. SUSHMA REDDY, 1 S T
YEAR POST GRADUATE(MD ANAESTHESIA)
MODERATOR: DR. SURYA NARAYANA ,
ASSISTANT PROFESSOR
MD ANAESTHESIA
NRIIMS
SANGIVALASA

2
CONTENTS:
Dermatomes
Types Of Needles
Different Approaches
Indications And Contraindications
Procedure
Complications
Clinical Situations Encountered In The Practice Of Spinal Anesthesia
Recent Developments In Spinal Anesthesia

3
History of Spinal Anaesthesia:
oCarl Koller, an ophthalmologist from Vienna, in 1884 first described the use of
topical cocaine for analgesia of the eye.
oWilliam Halsted and Richard Hall, surgeons at Roosevelt Hospital in New York
City, took the idea of local anesthesia a step further by injecting cocaine into
human tissues and nerves to produce anesthesia for surgery.
oJames Leonard Corning, a neurologist in New York City, in 1885 described the
use of cocaine for spinal anesthesia.

4
History of Spinal Anaesthesia:
Dural puncture was described in 1891 by Essex Wynter followed shortly by
Heinrich Quincke 6 months later.
Augustus Karl Gustav Bier, a German surgeon, used cocaine intrathecally in
1898 on six patients for lower extremity surgery.
In true scientific fashion, Bier decided to experiment on himself and developed
a post epidural puncture headache (PDPH) for his efforts.

6
Membranes of the Spinal Cord:
The three membranes that protect the spinal cord are the dura mater, arachnoid
mater, and pia mater.
The dura mater, or tough mother, is the outermost layer.
The dural sac extends to the second sacral vertebra (S2).
The arachnoid mater is the middle layer, and the subdural space lies between
the dural mater and arachnoid mater.

7

8
The arachnoid mater, or cobweb mother, also ends at S2, like the dural sac.
The pia mater, or soft mother, clings to the surface of the spinal cord and ends
in the filum terminale, which helps to hold the spinal cord to the sacrum.
The space between the arachnoid and pia mater is known as the subarachnoid
space, and spinal nerves run in this space, as does CSF.

9

10
Length of the spinal cord:
The length of the spinal cord varies according to age.
In the first trimester, the spinal cord extends to the end of the spinal column, but
as the fetus ages, the vertebral column lengthens more than the spinal cord.
At birth, the spinal cord ends at approximately upper border of L3.

12
Length of the spinal cord:
In the adult, the terminal end of the cord, known as the conus medullaris, lies at
approximately lower border of L1.
However, MRI and cadaveric studies have reported a conus medullaris below
L1 in 19%–58% and below L2 in 0%–5%.
The conus medullaris may lie anywhere between T12 and L3.

14
Surface anatomy:
When preparing for spinal anesthetic block, it is important to accurately identify
landmarks on the patient.
The midline is identified by palpating the spinous processes.
The iliac crests usually are at the same vertical height as the fourth lumbar
spinous process or the interspace between the fourth and fifth lumbar vertebrae.
An intercristal line can be drawn between the iliac crests to help locate this
interspace.

15
Surface anatomy:
Care must be taken to feel for the soft area between the spinous processes to
locate the interspace.
Depending on the level of anesthesia necessary for the surgery and the ability to
feel for the interspace, the L3–L4 interspace or the L4–L5 interspace can be used
to introduce the spinal needle.
Because the spinal cord commonly ends at the L1-to-L2 level, it is conventional
not to attempt spinal anesthesia at or above this level.

19
Dermatomes:
oIt would be incomplete to discuss surface anatomy without mentioning the
dermatomes that are important for spinal anesthesia.
oA dermatome is an area of skin innervated by sensory fibers from a single spinal
nerve.
oTo achieve surgical anesthesia for a given procedure, the extent of spinal
anesthesia must reach a certain dermatomal level.

21
Dermatomes:
 T10 dermatome corresponds to the umbilicus.
T6 dermatome corresponds to the xiphoid.
T4 dermatome corresponds to the nipples.
T12 –L1 dermatome corresponds to the groin or inguinal area.
L3 dermatome corresponds to the knee

22
Dermatomal levels of spinal anesthesia for common surgical procedures:
Procedure Dermatomal Level
Upper abdominal surgery
T4
Intestinal, gynecologic, and urologic surgery
T6
Transurethral resection of the prostate
T10
Vaginal delivery and hip surgery
T10
Thigh surgery and lower leg amputations
L1
Foot and ankle surgery
L2
Perineal and anal surgery
S2 to S5 ( saddle block)

23
Uptake Of LA From CSF:
Factors affecting LA uptake in Neural tissue:
LA concentration in CSF
Surface area of neural tissue exposed to LA
Lipid content of nerve
Blood flow of nerve
Elimination of LA from CSF:
Vascular absorption via subarachnoid and epidural blood vessels.

24
Factors Affecting Level Of Spinal Block:
Site of injection
Age of the patient
Baricity of the drug
Position of the patient
Speed of the injection
Volume, concentration and dose of the drug used

25
Factors Affecting Level Of Spinal Block:
More important Less important Not important
Drug factors  Dose
 Baricity
 Volume
 Concentration
 Temperature of injection
 Viscosity
 Additives other than
opioids
Patient factors  CSF volume
 Advanced age
 Pregnancy
 Weight
 Height
 Spinal anatomy
 Intra abdominal pressure
 Menopause
 Gender
Procedure factors  Patient position
 Epidural injection post
spinal
 Level of injection
(hypobaric more than
hyperbaric)
 Fluid currents
 Needle orifice direction
 Needle type

26
HYPERBARIC HYPOBARIC ISOBARIC
Density is greater than
CSF and follows gravity
Density less than CSF
and rise against
gravity
Density same as CSF and
remain at same level
Formed by addition of
dextrose (50 -80 mg/ml)
Formed by Addition
of sterile water or
opioids
Bupivacaine (0.5% in 8%
dextrose ,0.75% in 8%
dextrose)
Lidocaine (5% in 7.5%
dextrose)
Lidocaine (0.5% in
H2O)
Bupivacaine (0.5% in
H2O)
Lidocaine (2% in H2O)

27
Mechanism of Action:
Small preganglionic sympathetic fibers (B fibers) are the most sensitive and Motor fibers A-
alpha are most resistant.
Sensory fibers- C fibers (cold temperature) > A-delta (pinprick) > A beta (touch)
Smaller and myelinated fibers are blocked more easily than larger and unmyelinated fibers
Regression of blockade follows reverse order: motor function followed first by touch, then
pinprick, and finally cold sensation

28
Two segment Regression :
The time from injection of the first dose of local anaesthetic to the point where maximum
sensory level has receded by two segments.
Differs with the Local Anaesthetic used.

29
Physiological Effects :
Cardio vascular :
Sympathetic blockade leads to vasodilation of venous capacitance vessels> Pooling of blood in
LL > reduced preload and afterload > reduced stroke volume
Venous pooling and arterial dilation > Hypotension
Cardiac output maintained or slightly decreased during onset of SAB
Bradycardia- blockage of cardio acceleratory fibers (T1-T4)
Decrease in coronary blood flow.

30
Respiratory Effects :
Effect occurs during high spinal blockade which causes paralysis of abdominal and intercostal
muscles affecting the active exhalation
 ABG is normal in high spinal because of sparing of phrenic nerve and normal diaphragmatic
function and inspiration is minimally affected.
 Rarely, respiratory arrest can occur due to hypo perfusion of respiratory center in the
brainstem
In patients with COPD , using accessory muscles for adequate ventilation spinal anesthesia can
cause paralysis of muscles. Hence careful monitoring is required.

31
Gastrointestinal Effects :
Unopposed parasympathetic activity:
Hyperperistalsis
Nausea, vomiting
Increased secretions, relaxed sphincters, bowel constriction
Renal effects :
Spinal anaesthesia at lumbar level (S1-S4) impair bladder function causing urinary
retention until block wears off.

32
CNS :
Spinal anaesthesia have sedative effect and it reduces anesthetic requirements of midazolam,
propofol, fentanyl and volatile agents
Endocrine :
Decrease catecholamine release → suppress the neuroendocrine stress response to surgery →
Reduction of protein metabolism , hyperglycemia, sodium and water retention, tachycardia,
fever.

33
Thermoregulation :
Sympathetic blockade → Vasodilation → redistribution of blood and heat to periphery →
decrease in core body temperature → Shivering and peripheral vasoconstriction above the level
of spinal anaesthesia
Prevented by Active warming by warm infusions, warm air, covering patient

34
Indications of spinal anaesthesia:
Spinal anesthesia is in common use for surgical procedures involving the lower abdomen,
pelvis, perineal and lower extremities.
It is beneficial for procedures below the umbilicus.
Spinal anesthesia is best for short procedures.
Sub Arachnoid Block can also be used for non anaesthetic purposes like Neural tap, CSF
analysis , Lumbar puncture.

35
Indications of spinal anaesthesia:
Lower extremity surgery
Perineum surgery
Pelvic girdle surgery
Lower and upper abdomen surgery
Lumbar spine surgery

36
Contraindications To Spinal Anaesthesia:
Absolute Contraindications Relative Contraindications
• Patient refusal • Inherited Coagulopathy
• Infection at the site of injection • Sepsis at distinct site other than injection site
• Uncorrected hypovolemia • Fixed cardiac output states
• Allergy to the drug to be given
• Indeterminate neurological disease , Anatomic abnormality of
spine like Kyphosis or scoliosis
• Increased intracranial pressure • Mitral and aortic stenosis, Hypertrophic obstructive
cardiomyopathy
• Inability to maintain stillness during needle insertion, bleeding
disorders
• Preexisting myelopathy or peripheral neuropathy

38
Structures pierced during SAB:

39
Structures pierced during SAB:
When performing a spinal anaesthesia using the paramedian approach, the spinal needle should traverse
• Skin
• Subcutaneous fat
• Paraspinous muscle
• Ligamentum flavum
• Dura mater
• Subdural space
• Arachnoid mater
• Subarachnoid space

40
Spinal preparation :
Informed consent
Resuscitation equipment
i/v access
ASA standard monitors
Sterile tray containing drapes, swabs , sterilizing solution, syringes , spinal needles, and local
anaesthetic for skin infiltration

41
Needles used in SAB:
Needles of different diameters and shapes have been developed for spinal
anesthesia.
The ones currently used have a close-fitting, removable stylet, which prevents
skin and adipose tissue from plugging the needle and possibly entering the
subarachnoid space.
Needles are available in different sizes 16G to 30G, length is 8-10 cm ( 2.25 –
3.35cm for children , 15 cm for obese)

43
Cutting type: Cut through the duramater, Beveled tip with cutting edges
1. Quincke Babcock
2. Pitkin
Splitting type : Pencil point tip, spread the Dural fibers, needle hole is on side of the shaft. Less
incidence of PDPH.
1. Whittacre
2. sprotte

44
The pencil-point needles (Sprotte and Whitacre) have a rounded, noncutting
bevel with a solid tip.
 The opening is located on the side of the needle 2–4 mm proximal to the tip of
the needle.
The needles with cutting bevels include the Quincke and Pitkin needles.
The Quincke needle has a sharp point with a medium-length cutting needle, and
the Pitkin has a sharp point and short bevel with cutting edges.

45
The Greene spinal needle has a rounded point and rounded noncutting bevel.
 If a continuous spinal catheter is to be placed, a Tuohy needle can be used to
find the subarachnoid space before placement of the catheter.
Pencil-point needles provide a better tactile sensation of the layers of ligament
encountered but require more force to insert than bevel-tip needles.
The bevel of the needle should be directed longitudinally to decrease the
incidence of PDPH.

48
Position of the patient:
Proper positioning of the patient for spinal anesthesia is essential for a fast, successful nerve
block.
It has been shown to be an independent predictor for successful first attempt at neuraxial nerve
block.316 Many factors come into play for positioning of the patient.
Before beginning the procedure, both the patient and the anesthesiologist should be comfortable.
This includes positioning the height of the operating room table, providing adequate blankets or
covers for the patient, ensuring a comfortable room temperature, and providing sedation for the
patient if required.

49
Position of the patient:
There are three main positions for administering a spinal anesthetic:
1.The Lateral Decubitus Position
2. Sitting Position
3. Prone Position

50
Lateral Decubitus Position:

51
Lateral Decubitus Position:

52
Sitting and saddle block:
For low lumbar and sacral anaesthesia
Obese patient
Difficult to find midline e.g in scoliosis
Saddle block – patient to remain in sitting position for atleast 5 min after hyperbaric
spinal anaesthetic is placed.
If higher level blockade is required, place the patient to supine position
immediately.

54
Prone – Jack knife:
Appropriate for rectal , perineal or lumbar procedures.
Hypobaric or isobaric solution of LA is used.
Disadvantage – CSF has to be aspirated for correct needle tip placement as CSF
will not freely flow through the needle.

55
Prone – Jack Knife Position:

56
Technique Of Lumbar Puncture :
After correctly positioning the patient palpate the midline
Palpate the iliac crests and draw a line between them, corresponds to body of L4or L4-L5
interspace.
The skin should be cleaned with skin preparation solution such as 0.5% chlorhexidine, and the
area should be draped in a sterile fashion.
 The skin preparation solution should be allowed to dry, and unused skin preparation solution
must be removed from the anesthesiologist’s workspace.
A small wheal of local anesthetic is injected into the skin at the planned site of insertion.

57
Technique Of Lumbar Puncture :
More local anesthetic is then administered along the intended path of the spinal
needle insertion to the estimated depth of the supraspinous ligament.
This serves a dual purpose: additional anesthesia for the spinal needle insertion
and identification of the correct path for spinal needle placement.
Care must be taken in thin patients to avoid dural puncture, and inadvertent
spinal anesthesia, at this stage.

58
Approaches for SAB:
Midline or Median approach
Paramedian or Lateral approach
Taylor’s approach
Continuous Catheter techniques

59
Midline or Median approach :
Insert introducer at a slight cephalad angle of 10 to 15 degree
Pass the spinal needle through introducer
As spinal needle passes resistance changes
When spinal needle goes through dura mater “pop” is felt
Remove the stylet and check for flow of CSF
If no flow, rotate the needle 90° as needle orifice might be obstructed

60
If required withdraw the needle slightly and clear the orifice
If needle contacts bone, withdraw the needle back to skin level and redirect the
needle in more cephalad direction
If paresthesia occur remove the stylet, if CSF seen and paresthesia no longer
present, inject LA but if no CSF flow remove the needle and redirect toward the
side opposite the paresthesia

61
If Blood flows from the spinal needle, wait. If the blood becomes pinkish and
finally clear, inject LA but if blood only continues to drip, then it is likely that
the needle tip is in an epidural vein and it should be advanced a little further to
pierce the dura.
After free flow of CSF established, steady the spinal needle, attach the syringe
with drug, aspirate the CSF and inject LA at 0.2ml/s

63
Paramedian approach :
Used where diffuse calcification of interspinous ligament or difficulty in flexing
spine.
Palpate superior and inferior lumbar spinous processes of desired space, LA is
infiltrated 1 cm lateral to the superior aspect of inferior spinous process.
Direct the needle slightly medially 10-15° with cephalad angulation.
If lamina contacted ,withdraw the needle and redirect it more cephalad.
Ligamentum flavum is the first resistance identified.

66
Taylor’s or Lumbosacral Approach:
Paramedian approach directed towards L5 –S1 interspace.
 Used when other approaches fail or cannot be performed.
 Needle is inserted 1 cm medial and inferior to the posterior superior iliac spine, then angled 45
- 55° and medially.
This angle should be medial enough to reach the midline at the L5-S1 interspace.
After needle insertion, the first significant resistance felt is the ligamentum flavum and then the
Dura mater is punctured to allow free flow of CSF as the sub arachnoid space is entered.

68
Continuous Catheter Technique :
An indwelling catheter can be placed for continuous spinal anesthesia.
Local anesthetics can be dosed repeatedly through the catheter and the level and duration of
anesthesia adjusted as necessary for the surgical procedure.
Placement of a continuous spinal catheter occurs in a similar fashion as a regular spinal
anesthetic except that a larger-gauge needle, such as a Tuohy, is used to enable the passage of the
catheter.
After insertion of the Tuohy needle, the subarachnoid space is found, and the spinal catheter is
passed 2–3 cm into the subarachnoid space.
If there is difficulty in passing the catheter, attempt to rotate the Tuohy needle 180°.
Never withdraw the catheter back into the needle shaft because there is a risk of shearing the
catheter and leaving a piece of it in the subarachnoid space.

69
Continuous Catheter Technique :
If the catheter needs to be withdrawn, withdraw the catheter and needle together and attempt the
continuous spinal at another interspace.
Communication is critical to avoid a spinal catheter being mistaken for the more common
epidural catheter.
Because the needle used to pass the spinal catheter is a large-bore needle, there is a much higher
risk of PDPH, especially in young female patients.
Cauda Equina Syndrome can occur with small spinal catheters, so the FDA has advised against
using catheters smaller than 24 gauge for continuous spinal anesthetics.

70
Assessment of Spinal Anaesthesia :
Sensory assessment : cold sensation and pinprick for C and A delta fibers.
Loss of cold sensation occurs first, tested by ethyl chloride spray or ice and
represents cephalad peak height .
Then loss of sensation to pinprick occurs followed by loss of sensation of touch.
Motor assessment : most commonly used is modified Bromage scale which
represents only lumbosacral motor fibers.

71
Assessment of Spinal Anaesthesia :
Modified Bromage scale
0: no motor block
1: inability to raise extended leg ; able to move knees and feet
2: inability to raise extended leg and move knees; able to move feet
3: complete block of motor limb

72
Complications Of Spinal Anaesthesia:
Minor Moderate Major
 Nausea and vomiting  Failed spinal  Direct needle trauma
 Mild Hypotension  Post dural puncture headache  Infection ( abscess, meningitis)
 Shivering  Vertebral canal hematoma
 Pruritis  Spinal cord ischemia
 Urinary retention  Cauda equina syndrome
 Transient mild hearing
impairment
 Arachnoiditis, spinal
hematoma
 Backache  Peripheral nerve injury
 Total spinal anaesthesia
 Cardiovascular collapse
 Death

74
Vasovagal syncope :
Neuro cardiogenic response
Characterized by an inappropriate combination of bradycardia and paradoxical vasodilation
Vasodilation of blood vessels causes temporary decrease in blood pressure which leads to light
headedness or even fainting
Sudden parasympathetic activation (vagotonia) and sympathetic withdrawal can cause vasovagal
response
Causes are severe pain, anxiety, fear, and emotional stress
Treatment: reverse Trendelenburg position and i/v fluids

75
Treatment of hypotension :
Hypotension is SBP < less than 30 % from the baseline.
 Co-loading the patient with fluids
Trendelenburg position – not exceed 20° with raising upper body with pillow
under the shoulders
100% Oxygen therapy

76
Nausea and Vomiting :
Nausea and vomiting presenting after Spinal Anaesthesia are distressing for the patient and may impede
the surgeon.
Incidence of intraoperative nausea and vomiting ( IONV ) in non obstetric surgery can be upto 42 %
and may be as high as 80% in parturients.
Causes :
Vagal hyperactivity
Anxiety
Increased gastric pressure
Hormonal changes
Peritoneal traction , exteriorization of the uterus
Systemic opioids, Uterotonic drugs, Antibiotics
Decreased Lower Esophageal Sphincter tone

77
Nausea and Vomiting :
Spinal anesthesia itself may cause IONV or PONV via variety of mechanisms including
Hypotension, Intrathecal additives, Inadequate nerve block, or high nerve block.
Risk factors for IONV :
Peak nerve block height > T6
Baseline heart rate 60bpm or more
History of motion sickness
Previous h/o hypotension after spinal nerve block

78
High or Total Spinal :
Results from excessive spread of LA intrathecally or inadvertent spinal injection of epidural dose of LA
When block extends to cranial nerves- ‘Total Spinal’
Signs and symptoms:
 Hypotension
 Bradycardia
 Dyspnea
 Nausea and vomiting
 Tingling / numbness/ weakness
 Inability to cough
 Loss of consciousness
 Cardiac arrest

79
Post Dural Puncture Headache :
Frontal or occipital headache develops within 12- 48 hours after dural puncture and rarely after
5 days.
S/S develop within 15 min of sitting associated with neck pain, tinnitus, dizziness, diplopia,
hearing loss, cortical blindness, photophobia, cranial nerve palsies, nausea, vomiting and seizures
and relived after lying down.
Postulated cause is reduced CSF pressure, causing traction. Other cause is loss of CSF causes
vasodilation of the cerebral blood vessels.
The incidence of PDPH after spinal anesthesia performed with Quincke, an cutting needle, is
36% with 22 G needle, 25% with 25 G needle, 2% to 12% with 26 G needle, and less than 2%
for smaller than 26 G needles

80
Treatment :
Supportive measures
Bed rest supine position
Intravenous fluids, hydration
Analgesics (acetaminophen, NSAID’s, opiates)
Pharmacologic therapy
Methylxanthines –caffine (i/v 500mg of caffine sodium benzoate and orally 300mg).
Caffeine increases cerebral vasoconstriction by blocking adenosine receptors and leads to augmented CSF
production by stimulating sodium-potassium pumps

81
Epidural blood patch :
Gold standard
Stops CSF loss by formation of clot over the defect in meninges, restores CSF
pressure, by tamponade effect and reflex cerebral vasoconstriction
Perform at or below the meningeal puncture level. 15 mL of blood will spread
over a mean distance of nine spinal segments , spread is caudal.
Performed after failure of conservative treatment or 24hrs after Dural puncture
second epidural blood patch may be performed 24 to 48 hours after the first in
the case of ineffective or incomplete relief of symptoms
Side effects- aching in back, buttocks , legs

82
Neurological complications :
Postoperative peripheral neuropathies- injury to nerve roots
Paraplegia, loss of bowel/bladder function - direct injury to spinal cord
Infective meningitis /arachnoiditis- infected tray , LA , oral flora of doctor without mask
Spinal hematoma
oPatients on anticoagulants
oElderly
oFemale
oTraumatic needle or catheter insertion
oPlatelet count < 75,000 /mm3

83
Clinical Situations Encountered In The Practice Of Spinal
Anesthesia :
The Difficult and Failed Spinal :
Failed spinal anesthesia may present as complete absence of nerve block, partial
nerve block, or inadequate duration of nerve block.
A methodical approach is required when managing failed spinal block.
This can be failure of lumbar puncture, failure of solution injection, solution spread
in the CSF, drug action on the nerve roots and cord, and patient management.

84
Anesthesia :
Inadvertent Subdural Nerve Block :
Failed subarachnoid nerve block may be the result of inadvertent subdural injection and deserves special attention.
The subdural space is a potential space that only becomes real after tearing of neurothelial cells within the space
as a result of iatrogenic needle insertion and fluid injection.
Characteristic features of a SDB are a high sensory level with motor and sympathetic sparing.
This may be the result of the limited ventral capacity of the space, which results in sparing of the anterior motor
and sympathetic fibers.
However, a SDB may also present in a number of different ways: failed nerve block, unilateral nerve block,
Horner syndrome, trigeminal nerve palsy, respiratory insufficiency, or unconsciousness due to brainstem
involvement.
Onset of nerve block is slower than subarachnoid nerve block but faster than epidural nerve block and usually
resolves after 2 hours.

85
Anesthesia :
Unilateral Spinal Nerve Block :
Unilateral spinal anesthesia was described in 1950 by Ruben and Kamsler.
Use of unilateral spinal anesthesia results in decreased changes in systolic, mean and diastolic
pressures, or oxygen saturation in elderly trauma patients.
Keeping the operative side up and using a hypobaric spinal solution in a low dose for these
cases results in excellent anesthesia and remarkable hemostability when the patient is kept in the
lateral position for 5–10 minutes before repositioning supine.
When using hyperbaric solutions, the operative side should be dependent.

86
Anesthesia :
The Anti coagulated Patient :
The risk of epidural and spinal hematoma in patients on antiplatelet therapy has been raised by a
case report of spontaneous epidural hematoma formation in the absence of spinal or epidural
anesthesia in a patient with a history of aspirin ingestion.
The patients on antiplatelet medications showed a higher incidence of blood aspiration through
the spinal or epidural needle or the catheter.
Female gender, increased age, history of excessive bruising or bleeding, continuous catheter
technique, large needle gauge, multiple attempts, and difficult needle placement are significant
risk factors.
The risk factors for increased bleeding and spinal hematoma include the patient’s intake of
several antiplatelet drugs and making multiple attempts.

87
Recent Developments In Spinal Anesthesia :
Neuraxial Ultrasound :
The first description of ultrasound-assisted lumbar puncture was in 1971.
More recently, neuraxial ultrasound has been used as a pre procedure scan and for real-time
needle placement.
Scanning decreases needle attempts, accurately predicts depth to the epidural space, and may
improve the success rate.
Ultrasonography allows increased accuracy at identifying lumbar interspaces.
This is important as palpation of the lumbar spine is likely to generate a higher interspace than
expected, and the Conus medullaris has been shown to be at times lower than the conventionally
taught L1 level.

89
Laparoscopic Surgery With Lumbar Spinal Anesthesia :
Lumbar spinal anaesthesia has been used in the settings of laparoscopic extra peritoneal and
intraperitoneal inguinal hernia repair, outpatient gynaecological laparoscopy, laparoscopic
cholecystectomy, and laparoscopic ventral hernia repair.
Anxiolytics should be offered, and patients should be counseled about expected sensations.
Pneumoperitoneum can be perceived as a weight on the abdomen.
 The possibility of conversion to general anesthesia, which is often due to shoulder tip pain,
should be discussed.
Addition of intrathecal fentanyl or clonidine may decrease shoulder tip pain.
The main two drawbacks of spinal anesthesia for laparoscopic cholecystectomy seemed to be
shoulder tip pain resulting in patient dissatisfaction or conversion to general anesthesia and a
high rate of PDPH.

90
Thoracic Spinal Anaesthesia :
Thoracic spinal anesthesia was described in the early 1900s by Professor Thomas Jonnesco.
He called his technique “general spinal analgesia” and described two puncture sites, the T1–T2
and T12–L1 interspaces, depending on the surgery required.
In 2006, thoracic spinal anesthetic for a patient requiring laparoscopic cholecystectomy was
reported.
Spinal anesthesia is traditionally performed in the lumbar region below the level of the conus
medullaris to avoid injury to the spinal cord. However, MRI images, albeit in a supine position,
have shown that the mid- to lower thoracic segment of the cord lies anteriorly, such that there is
a CSF-filled space between the dura and the cord

91
 Midline MRI of the spinal column.
 In the thoracic segments, the spinal cord is
positioned anteriorly leaving a significant space
between the posterior Dura and the spinal cord.
 At the lumbar level, the space disappears almost
completely.

92
Clinical significance:
Neuraxial anesthesia offers many benefits that are not available with general anesthesia.
Neuraxial anesthesia has made it possible to perform many major procedures on an awake
patient.
For example, cesarean sections can be better and safely performed via neuraxial anesthesia than
with general anesthesia, which allows the establishment of bonding between a mother and her
neonate to take place immediately

93
References :
1. Miller’s Textbook Of Anaesthesia , 9th
Edition
2. Morgan & Mikhail's Clinical Anaesthesiology , 7th
Edition
3. NYSORA Textbook of Regional Anaesthesia
4. Barasch Clinical Anaesthesia , 6th
Edition
5. Sharma SK, Gambling DR, Joshi GP, et al. Comparison of the 26-guage Atraucan®️and 25-
guage Whitacre needles: insertion characteristics and complications. Can J Anaesth 1995; 42:
706–10
6. Broadbent CR, Maxwell WB, Ferrie R, Wilson DJ, Gawne-Cain M, Russell R. Ability of
anaesthetists to identify a marked lumbar interspace. Anaesthesia. 2000 Nov;55(11):1122-6.

Subarachnoid block a brief insight .pptx

More Related Content

Similar to Subarachnoid block a brief insight .pptx

More from RasheedShaik35

Recently uploaded

Subarachnoid block a brief insight .pptx