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Spinal Anesthesia: Apractical guide.

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Title: Spinal Anesthesia: Apractical guide.


1
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2
Neuroaxial AnesthesiaAn overview.
  • Dr. Mahmoud Othman MD,
  • Professor Of Anesthesia and SICU,
  • Depart. of Anesthesia and SICU,
  • Mansoura Faculty Of Medicine

3
The Advantages of Neuroaxial Anaesthesia
1.Cost.. 2.Patient satisfaction. 3.Respiratory
disease. 4.Patent airway. 5.Diabetic patients.
6.Muscle relaxation. 7.Bleeding. 8.Splanchnic
blood flow. 9.Visceral tone. 10.Coagulation.
4
Physiology ..
  • -Sensory Block . . .
  • -Motor block
  • -Autonomic Block. .
  • Anatomy .. ..
  • Pharmacology .. ..

5
Today PNS spinal cord Tomorrow CNS
6
Nervous system
Central nervous system (CNS) brain spinal cord
Peripheral nervous system (PNS) nerves outside
brain and s.c.
Somatic NS nerves going from sense organs to CNS
from CNS to muscles glands
Autonomic NS controls heart, blood
vesseles,intestines, other organs
Sympathetic NS for vigerous activity (fight or
flight)
Parasympathetic NS vegetative, nonemergency
responses
7
Peripheral NS
  • Somatic NS
  • Sense organs ? CNS ? muscles and glands
  • Something touches leg ? message to brain ?
    message from brain to arm muscle ? brush thing
    off leg

Sensory stimulation Motor response

8
Physiology
http//www.carleton.ca/ics/courses/cgsc5001/img/06
/neuron.jpg
http//home.earthlink.net/dayvdanls/REFLEXARC.GIF
9
Bell-Magendie law The entering dorsal roots
carry sensory information to the brain the
exiting ventral roots carry motor information to
the muscles and glands In other words
Dorsalsensory Ventralmotor
http//www.unm.edu/jimmy/spinal_neurons.jpg
10
Dorsal root (sensory in)
rostral
Ventral root (motor out)
11
The Spinal Cord
The Spinal Cord
Figure 4.7, p82
http//www.bcs.rochester.edu/dlee/bcs245/spinal_c
ord.jpg
Know above terms (for left figure) terms
circled in red for right figure!! To be clear,
DRG collections of cell bodies of sensory
neurons cell bodies of motor neurons are within
SC
12
Peripheral NS
  • Autonomic NS
  • Sympathetic NS axons activate organs for fight
    or flight
  • (Thoraco-lumber outflow) T1 to L2
  • Sympathetic ganglia are closely linked and act
    in sympathy with each other

Short pregang.
Long postgang.
13
Facilitates energy expenditure Behaviors?
Physiology? Fibers (short pre, long post,
NT?)
14
Peripheral NS
  • Autonomic NS
  • Parasympathetic NS facilitate vegetative,
    nonemergency functions
  • Para means beside or related to opposite
    action of sympathetic NS
  • (Cranio- sacral outflow) Cr1-12 S2-4
  • consists of cranial nerves and nerves of sacral
    SC

long pregang. short postgang.

15
Facilitates energy conservation Behaviors?
Physiology? Fibers (long pre, short post,
NT?)
16
Neurotransmitters
Few exceptions sweat glands stimulated by Ach.
http//members.aol.com/Bio50/LecNotes/LNPics/ln26a
.gif
Why does that matter?? Drugs!! OTC cold meds
block parasymp or increase symp activity b/c flow
of sinus fluids is parasympathetic. Side effect
inh salivation digestion and inc HR
17
Spinal anesthesia
18
Spinal nerves
Cauda equina
http//dentistry.ouhsc.edu/intranet-web/Courses/DH
3342/images/spin_nerves.JPG
19
Myelin Sheath
20
Types of Nerve Fibers
21
  • Physiology of neuroaxial blockage
  • 1. zone of differential block
  • level block (sympathetic gt sensory gt moter
    )
  • 2. nervous system
  • Sodium channel block nerve root ,spinal
    cord
  • 3. cardiovascular system
  • Autonomic denervation? vasodilatation?decrease
    venous return?decrease CO? hypotension
  • Decrease HR
  • 4. respiratory system
  • 5. GI system parasympathetic? increase bowel
    move
  • rupture of distened bowel
  • 6. Liver and kidney
    .


22
Vertebral Columen Curves
23
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24
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25
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26
Lumber Vertebrae Anatomy
27
Spinal Cord Terminal
28
The spinal cord usually ends at the level of L1
in adults and L3 in children. Dural puncture
above these levels is associated with a slight
risk of damaging the spinal cord and is best
avoided. An important landmark to remember is
that a line joining the top of the iliac crests
is at L4 to L4/5
29
Local Anesthestic
A substance which reversibly inhibits nerve
conduction when applied directly to tissues at
non-toxic concentrations
30
Local Anesthetics- History
  • 1860 - cocaine isolated from erythroxylum coca
  • Koller - 1884 uses cocaine for topical anesthesia
  • Halsted - 1885 performs peripheral nerve block
    with local
  • Bier - 1899 first spinal anesthetic

31
Local anesthetics - Mechanism
Limit influx of sodium, thereby limiting
propagation of the action potential.
32
Mechanism of action
  • Local anesthetics block generation, propagation,
    and oscillations of electrical impulses in
    electrically excitable tissue.
  • Mainly by acting on Sodium channels.

33
Local Anesthetics - Classes
Esters
Esters
34
PHARMACOLOGY AND PHARMACODYNAMICS
  • Clinically used local anesthetics consist of
    lipid-soluble, substituted benzene ring linked to
    amine group via alkyl chain containing either an
    amide or ester linkage.
  • Type of linkage separates local anesthetics
    into either aminoamides (metabolized in liver) or
    aminoesters (metabolized in liver or by plasma
    cholinesterase).

35
Local anesthetics - Classes (Rule of is)
Esters Cocaine Chloroprocaine Procaine
Tetracaine
Amides Bupivacaine Lidocaine Ropivacaine
Etidocaine Mepivacaine
36
Cinchocaine (Nupercaine, Dibucaine, Procaine,
Sovcaine). 0.5 hyperbaric (heavy) solution is
similar to bupivacaine. Amethocaine
(Tetracaine, Pantocaine, Pontocaine, Decicain,
Butethanol, Anethaine, Dikain). A 1 solution can
be prepared with dextrose, saline or water for
injection. Mepivacaine (Scandicaine,
Carbocaine, Meaverin). A 4 hyperbaric (heavy)
solution is similar to lignocaine.
37
Bupivacaine (Marcaine). 0.5 hyperbaric (heavy)
bupivacaine is the best agent to use if it is
available. 0.5 plain bupivacaine is also
popular. Bupivacaine lasts longer than most other
spinal anaesthetics usually 2-3 hours.
Lignocaine (Lidocaine/Xylocaine). Best results
are obtained with 5 hyperbaric (heavy)
lignocaine which lasts 45-90 minutes.
38
Local Anaesthetics for Spinal Anaesthesia. Local
anaesthetic agents are either heavier
(hyperbaric), lighter (hypobaric), or have the
same specific gravity (isobaric) as the CSF.
Hyperbaric solutions tend to spread below the
level of the injection, while isobaric solutions
are not influenced in this way. It is easier to
predict the spread of spinal anaesthesia when
using a hyperbaric agent. Hypobaric agents are
not generally available.
39
ADDITIVES TO LOCAL ANESTHETICS
  • (1)Epinephrine
  • Epinephrine added to local anesthetic may
  • prolong block
  • increase intensity of block
  • decrease systemic absorption
  • Epinephrine analgesia may act via interaction
    with 2-adrenergic receptors in spinal cord and
    brain

40
Addatives to spinal anesthesia (Cont.)
  • (2)Analgesics

A-Opioids .. .. . .. As 1-
Fentanyl 2-Colinidine B-Non-opioids As
1- Tramadol
2- Midazolam 3-Neostigmine.
41
Advantages
  • - cost. ..
  • -Patient Satsifaction
  • -Respiratory Diseases.
  • -Diabetic Patients
  • - Muscle Relaxation.
  • -Surgical Bleeding
  • -Visceral Tone. ..
  • -Coagulation(DVT, PE).

42
  • Indications for Neuroaxial Anaesthesia
  • A- Spinal anaesthesia is best
    reserved for operations below the
    umbilicus e.g. hernia repairs , gynaecological
    and urological
    operations and any operation on the perineum
    or genitalia.
  • B- Spinal anesthesia applied for All
    operations on the legs (orthopedic-Vascular)
    but an amputation , though
    painless, may be an unpleasant experience for
    an awake patient.

43
  • C - Older patients and those with
    systemic disease such as chronic respiratory
    disease, hepatic, renal and endocrine disorders
    such as diabetes.
  • D- It is suitable for managing patients with
    trauma if they have been adequately resuscitated
    and are not hypovolaemic.
  • E- In obstetrics, it is ideal for manual
    removal of a retained placenta (again, provided
    there is no hypovolaemia). Also spinal
    anesthesia is best choice for casearan section
    and instrumental dlivery There are definite
    advantages for both mother and baby in
    comparison to general anesthesia
  • .

44
Preoperative Visit
  • Indications of spinal anesthesia
  • -General surgery .
  • -Orthopedic surgery .
  • -Gynacological surgery
  • -Obestatric surgery.
  • -Urological surgery.
  • -Vascular surgery.
  • Medical Examination
  • Laboratory Investigations

  • Intravenous Preloading

45
Contraindictions Of Neuroaxial Anesthesia
  • .Inadaquat Resuscitation Facilities.
  • Hypovolaemia
  • .Patient Refusal
  • .septicaemia ..
  • .Local infection
  • . Neurological Diseases . .
  • -Coagulation Defects.
  • .Infants and childern(expert anesthetist)

46
  • Absolute contraindications
  • 1. sepsis
  • 2. bacteremia
  • 3. skin infection at injection site
  • 4. severe hypovolemia
  • 5. coagulopathy
  • 6. increase intracranial pressure
  • 7. lack of consent

47
  • Relative contraindications
  • 1. peripheral neuropathy .
  • 2. uncooperative patients
  • 3. psychosis or emotional instability .
  • 4. Mini dose heparin .
  • 5. aspirin or anticoagulant drug .
  • 6. demyelating CNS .
  • 7. certain cardiac lesions (valve stenosis) .
  • 8. prolonged surgery.
  • 9. surgery of uncertain duration
  • 10. infants and young childern (experience) .
    .

48
Pre-operative Visit. Patients should be told
about their anaesthetic during the pre-operative
visit. It is important to explain that although
spinal anaesthesia abolishes pain, they may be
aware of some sensation in the relevant area, but
it will not be uncomfortable and is quite normal.
They must be reassured that, if they feel pain
they will be given a general anaesthetic.
49
Premedication is not always necessary, but if a
patient is apprehensive, a benzodiazepine such
as 5-10 mg of diazepam may be given orally 1 hour
before the operation. Other sedative or narcotic
agents may also be used. Anticholinergics such as
atropine or scopolamine (hyoscine) are unnecessary
50
Preparation for Lumbar Puncture. 1 . spinal
needle. 2 . Introducer 3 . 5ml syringe for the
spinal anaesthetic solution. 4 . 2 ml syringe for
local anaesthetic to be used for skin
infiltration. 5 . selection of needles for
drawing up the local anaesthetic solutions and
for infiltrating the skin. 6 . gallipot with a
suitable antiseptic for cleaning the skin, eg
chlorhexidine, iodine, or methyl alcohol. 7 .
Sterile gauze swabs for skin cleansing.
51
8 . sticking plaster to cover the puncture
site. The local anaesthetic to be injected
intrathecally should be in a single use ampoule.
Never use local anaesthetic from a multi-dose
vial for intrathecal injection.
52
Pre-loading. All patients having spinal
anaesthesia must have a large intravenous cannula
inserted and be given intravenous fluids
immediately before the spinal. The volume of
fluid given will vary with the age of the patient
and the extent of the proposed block. A young,
fit man having a hernia repair may only need 500
mls. Older patients are not able to compensate as
efficiently as the young for spinal-induced
vasodilation and hypotension and may need 1000mls
for a similar procedure. If a high block is
planned, at least a 1000mls should be given to
all patients. Caesarean section patients need at
least 1500 mls.
53
CO-spinal Fluid thrapy
-The fluid should preferably be normal saline or
Hartmann's solution. -Colloids like hetasrach,
dextran, can be used. -5 dextrose is readily
metabolised and so is not effective in
maintaining the blood pressure.
54
Position
  • 1. Lateral ( Lt lateral )
  • 2. Sitting
  • 3. Prone

55
Postioning Of Patient
56
The sitting position is preferable in the
obese whereas the lateral is better for
uncooperative or sedated patients.
57
Males tend to have wider shoulders than
hips and so are in a slight "head up" position
when lying on their sides, whilst for females
with their wider hips, the opposite is true.
58
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59
approach
  • 1.median approach
  • 2.paramedian approach

60
Spinal Technique
61
Anatomy. The skin. Subcutaneous fat.. The
supraspinous ligament The interspinous ligament
The ligamentum flavum The epidural space The
dura. sac. The subarachnoid space.
62
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63
Layers to be pierced
1-Skin 2-Sc tissues 3-Sup Spin
Lig 4-Inter Spin Lig 5-Lig Flavum 6-Epidural
Sp. 7-Dura Matter 8-Arachenoid 9-Subarach
Sp.
64
Continuous spinal anesthesia
65
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66
Assessing the Block. 1. the patient is unable to
lift his legs from the bed, the block is at least
up to the mid-lumbar region. 2. It is
unnecessary to test sensation with a sharp needle
3. It is better to test for a loss of
temperature sensation using a swab soaked in
either ether or alcohol. 4. the patient can be
gently pinched with artery forceps or fingers on
blocked and unblocked segments 5. Surgeons and
patients should be reminded that when a block is
successful, a patient may still be aware of touch
but will not feel pain.
67
Assessing Of Spinal Anesthesia
-Sp. gr.(CSF) 1.003-1.008 -Sp.gravity.
(bupivacaine) 0.5(heavy)
1.028.. -Sp.gravity.. (bupivacaine) 0.5(iso
baric) 1.006

68
Factors Affecting Spread Of Local Anesthetic
  • 1- Baricity (heavy-Isobaric) ...
  • 2-Position. .. .
  • 3-Volume injected .. . .
  • 4-Level of Injection,,, ..
  • 5-Concentration Of local anesth. .
  • 6- Speed Of injection.. . ... .
  • 7-Abdomial pressure(asites-pregnancy-tumours)
    .

69
In the horizontal supine position ,hyperbaric
local anesthetic solutions injected at the height
of the lumbar lordosis (circle) flow down the
lumbar lordosis to pool in the sacrum and in the
thoracic kyphosis. Pooling in the thoracic
kyphosis is thought to explain the fact that
hyperbaric solutions produce blocks with an
average height of T4-6.
70
spinal anesthesia level and duration of block
drug Level Level Level duration
drug L4 T10 T4 duration
Heavy(0.5 ) bupivacaine 4-8 mg. 8-12 mg 14-20 mg 90-110 min
Isobaric(0.5 ) bupivacaine 10-12 mg 12-15 mg 15-20 mg 180 min
71
  • Factors Affecting the Spread of the Local
    Anaesthetic Solution.
  • 1- The baricity of the local anaesthetic
    solution
  • 2- position
  • 3- Dosage , concentration
  • 4- volume injected
  • 5- the level of injection
  • 6- Speed of injection
  • 7- Abdominal pressure.

72
Problems With Spinal Block
  • 1-NO block at all .. ..
  • 2-Block is one sided .
  • 3-Block is not high enough .
  • 4-Block is too high..
  • 5-Nausea Vomiting . .. ......
  • 6-Shivering .. .

73
Monitoring. It is essential to monitor 1)
Pulse 2) Blood pressure 3)
Respiration 4) Consiosness
74
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75
Monitoring
  • 1-ECG trace. .
  • 2-Heart rate,. .
  • 3-Artial blood pressure. , ,, .. .. .. .
  • 4-Respiratory pattern.., ,, .. . ..
  • 5-Artial SpO2,,. .
  • 6-Level of consciousness,,,,..

76
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77
Disadvantages Of spinal Anesthesia
  • 1-Diffculty (Ageing-Deformity).. .
  • 2-hypotension(high level).
  • 3-Total spinal. .
  • 4-Longer Surgery(more than 2 hs) ..
  • 5-Psychological aspect(sedation)

78
CONt. Spinal Anesth.Disadavent.
  • 6-Postdural puncture headeche .. ..
  • 7-Risk of infection(meningitis) ..
  • 8-Risk of heamtoma(clotting defects)......
  • 9-Neurological injury(cauda equina) .
  • 10-Urine retension......

79
Complications
  • 1.Immediate complications

  • - hypotension
  • - total spinal block
  • - systemic toxicity
  • 2.Late complications

  • - post dural puncture headache (PDPH).
  • -Epidural hematoma .
  • - focal neurological deficit .
  • - bacterial meningitis .
  • -

80
  • Other Complications
  • As the sacral autonomic fibres are among the last
    to recover following a spinal anaesthetic,
    urinary retention may occur. If fluid pre-loading
    has been excessive, a painful distended bladder
    may result and the patient may need to be
    catherised.
  • Permanent neurological complications are
    extremely rare. Many of those that have been
    reported were due to the injection of
    inappropriate drugs or chemicals into the CSF
    producing meningitis, arachnoiditis, transverse
    myelitis or the cauda equina syndrome with
    varying patterns of neurological impairment and
    sphincter disturbances.

81
Vasopressors 1. Ephedrine 2.5-6mg titrated
against the blood pressure. Its effect generally
lasts about 10 minutes and it may need repeating.
It can also be given intramuscularly but its
onset time is delayed although its duration is
prolonged.. 2. Metaraminol (Aramine). 3.
Methoxamine (Vasoxine). 4. Phenylephrine. 5.
Noradrenaline (Levophed). 6. Adrenaline/Epinephri
ne.
82
Treatment of spinal Hypotension. Hypotension is
due to vasodilation and a functional decrease in
the effective circulating volume.
1.vasoconstrictor drugs 2.All hypotensive
patients should be given OXYGEN by mask until the
blood pressure is restored. 3. raising their
legs thus increasing the return of venous blood
to the heart. spinal anaesthetic has been
injected in the preceding 15 minutes as it will
result in the block spreading higher and the
hypotension becoming more severe.
83
4.Increase the speed of the intravenous infusion
to maximum until the blood pressure is restored
to acceptable levels . 5. pulse is slow, give
atropine intravenously.
84
Treatment of Total Spinal. 1. Hypotension -
Remember that nausea may be the first sign of
hypotension. give vassopressors. 2. Bradycardia
- give atropine 3. Increasing anxiety -
reassure. 4. Numbness or weakness of the arms
and hands, indicating that the block has reached
the cervico-thoracic junction. 5. Difficulty
breathing - as the intercostal nerves are blocked
the patient may state that they can't take a deep
breath. As the phrenic nerves (C 3,4,5) which
supply the diaphragm become blocked, the patient
will initially be unable to talk louder than a
whisper and will then stop breathing.
85
6. Loss of consciousness. Ask for help - several
pairs of hands may be useful! Intubate and
ventilate the patient with 100 oxygen. Once
the airway has been controlled and the
circulation restored, consider sedating the
patient with a benzodiazepine
86
  • Headache (PDPH)
    .
  • A characteristic headache may occur following
    spinal anaesthesia. It begins within 24-72 hours
    and may last a week or more.
  • It is postural, being made worse by standing or
    even raising the head and relieved by lying down.
  • It is often occipital and may be associated with
    a stiff neck. Nausea, vomiting, dizziness and
    photophobia frequently accompany it.
  • It is more common in the young, in females and
  • especially in obstetric patients.

87
  • It is thought to be caused by the continuing loss
    of CSF through the hole made in the dura by the
    spinal needle. This results in traction on the
    meninges and pain.

  • The incidence of headache is related directly to
    the size of the needle used. A 16 gauge needle
    will cause headache in about 75 of patients, a
    20 gauge needle in about 15 and a 25 gauge
    needle in 1-3.
  • As the fibres of the dura run parallel to the
    long axis of the spine, if the bevel of the
    needle is parallel to them, it will part rather
    than cut them and therefore, leave a smaller
    hole.

88
  • Treatment of spinal headache
  • .
  • 1. Remain lying flat in bed as this relieves the
    pain.
  • 2. They should be encouraged to drink freely or,
    if necessary, be given intravenous fluids to
    maintain adequate hydration.
  • 3. Simple analgesics such as paracetamol,
    aspirin or codeine may be helpful,
  • 4. Increased intra-abdominal and hence
    epidural pressure. (Abdominal binder).

89
  • 5. Caffeine containing drinks such as tea, coffee
    or Coca-Cola are often helpful.
  • 6. Prolonged or severe headaches may be treated
    with epidural blood patch performed by
    aseptically injecting 15-20ml of the patient's
    own blood into the epidural space. This then
    clots and seals the hole and prevents further
    leakage of CSF.
  • It used to be thought that bedrest for 24 hours
    following a spinal anaesthetic would help reduce
    the incidence of headache, but this is now no
    longer believed to be the case.

90
  • It is widely considered that pencil-point needles
    (Whiteacre or Sprotte) make a smaller hole in the
    dura and are associated with a lower incidence of
    headache (1) than conventional cutting-edged
    needles (Quincke)

To minimize PDPH
91
Headache prophylaxis with spinal anesthesia


92
Other complications
  • If inadequate sterile precautions are taken
    bacterial meningitis or an epidural abscess
  • Finally, permanent paralysis can occur due to
    'anterior spinal artery syndrome'.
  • This is most likely to affect elderly patients
    who are subjected to prolonged periods of
    hypotension and may result in permanent paralysis
    of the lower limbs.

93
Summary
  • (1) Advantages
  • (2) Physiology / Anatomy/
    Pharmacology
  • (3) Preoperative visit..
    Indications .
  • Examination.
  • Investigations..
  • Intravenous Preload of fluids
  • (4) Contraindications to neuroaxial
    anesthesia..
  • (5 ) Technique of neuroaxial anesthesia
    .....................
  • (6) Factors affect spread of neuroaxial spianl
    anesthes
  • (7) Monitoring during neuroaxial
    anesthesia.
  • (8) Complications and mangement of neuroaxial
    anesthesia

94
Thanks For Your Attention
Dr.Mahmoud Othman
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