Spinal Anesthesia Flashcards

1
Q

What is spinal anesthesia?

A

Reversible chemical blockade of neuronal transmission produced by the injection of a local anesthetic drug into the CSF contained within the subarachnoid space

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2
Q

What nerve fibers transmission are temporarily inhibited with spinal anesthesia?

A

Sensory
Autonomic
Motor

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3
Q

How might a spinal anesthetic speed the patients recovery?

A

Surgical stress is reduced by the afferent block

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4
Q

How might spinal anesthesia decrease the occurrence of venous thrombosis and blood loss?

A

Reduction of arterial and venous pressure

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5
Q

What postoperative complications can the incidence be lowered with spinal anesthesia?

A

Nausea/Vomiting
Sedation
Cognitive impairment
Wound pain

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6
Q

Why is it important to cycle the blood pressure cuff immediately after administering spinal anesthesia?

A

Sympathetic blockade accompanies spinal anesthesia virtually 100% of the time

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7
Q

What are some complications often associated with spinal anesthesia?

A

Urinary retention
Post-dural puncture headache
Intense motor blockade

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8
Q

Why do many patients fear having a SAB?

A

Fear of being awake, educate the patient that sedation will be provided

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9
Q

Why might a SAB be a safer option in a patient with a full stomach?

A

Vomiting and pulmonary aspiration is less likely (unless over sedated)Patients with difficult airways may be easier to manage

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10
Q

Why might a SAB be useful in patients undergoing a TURP procedure?

A

The conscious patient is able to tell if bladder perforation has occurred, CHF can be monitored and electrolyte disturbances could be assessed

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11
Q

What are the benefits of a laboring mother receiving SAB?

A

Somatic motor function loss can be minimized when the level is kept lowMother remains awake and can see the child

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12
Q

Why is a SAB beneficial for metabolic diseases?

A

It has minimal effect on metabolism, beneficial for

  • Liver disease
  • Kidney disease
  • Diabetes
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13
Q

What are some absolute contraindications to a SAB?

A
Patient refusal
Infection at the injection site
Coagulopathy or other bleeding diathesis
Severe hypovolemia
Severe aortic or mitral valve stenosis
Increased ICP
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14
Q

Why is a SAB contraindicated if a patient has an infection at the injection site?

A

Risk of skin core introducing infection into the CSF

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15
Q

What is a SAB contraindicated in aortic or mitral valve stenosis?

A

It causes a decrease in after load which causes a decrease in CO which can’t keep up with the vasodilation a SAB causes

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16
Q

What can occur if a SAB is performed on a patient with an increased ICP?

A

It can cause the patient to herniate

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17
Q

Why might it not be a good idea to give a patient with a demyelinating disease spinal anesthesia?

A

It could potentially cause an exacerbation of the disease if it was in remission

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18
Q

Why wouldn’t a provider choose to give a patient a SAB if they had a history of metastatic CA of the lumbar vertebrae?

A

There is a potential for neurologic deficit in these patients

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19
Q

How can HIV effect a providers choice in giving a patient spinal anesthesia?

A

There is a potential for neurologic disorder and there is a thought that you could potentially be introducing the virus to the CSF

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20
Q

What local anesthetic would patients have an allergy to and why?

A

Esters, preservative PABA

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21
Q

What might the provider expect if they gave spinal anesthesia to a patient with uncontrolled HTN?

A

Massive HoTN due to a low tank and a sympthomectomy

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22
Q

What is the thought behind administering 1000-1500mL of a balanced crystalloid solution prior to spinal anesthesia?

A

It is supposed to help prevent against HoTN however, likely not effective

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23
Q

What must the provider have available and functioning prior to spinal anesthesia and why?

A

A patent IV, anticipate giving vasoactive agents to treat the sympathomectomy

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24
Q

How many total vertebrae are present in the spinal column?

A

33 vertebrae

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25
Q

How many cervical vertebrae are present in the spinal column?

A

C1-C7 = 7

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26
Q

How many thoracic vertebrae are present in the spinal column?

A

T1-T12 = 12

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27
Q

How many lumbar vertebrae are present in the spinal column?

A

L1-L5 = 5

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28
Q

How many sacral vertebrae are present in the spinal column?

A

5 Fused

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29
Q

How many vertebrae are present in the coccyx of the spinal column?

A

4 Fused

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30
Q

What two spinal regions have a lordosis curvature?

A

CervicalLumbar

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31
Q

What two spinal regions have a kyphosis curvature?

A

ThoracicSacral

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32
Q

What is the laymen’s term for the coccyx?

A

Tailbone

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33
Q

What is the typical shape of a lumbar vertebrae?

A

Kidney shaped

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34
Q

What are the structures called where vertebrae come into contact with each other?

A

Superior articular processInferior articular process

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35
Q

What is the typical shape of the body of a thoracic vertebrae?

A

Heart shaped

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36
Q

What is the order from skin to the subarachnoid space does a need pass to get spinal anesthesia?

A
Skin
Subcutaneous tissue and fat
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space
Dura
Subarachnoid space
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37
Q

What is the tip of the spinal cord called and what is its function?

A

Conus Medullaris, it stabilizes the spinal cord

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38
Q

What is the name of the structure that extends beyond the conus medullaris as multiple nerves?

A

Cauda equina

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39
Q

What sensation can occur is the cauda equina is struck by a needle when attempting spinal anesthesia?

A

Paresthesis, however should resolve because they are floating structures

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40
Q

What is the outermost layer of the menenges that is tough, fibrous and runs longitudinally?

A

Dura mater

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41
Q

Where does the dura mater extend?

A

From the foramen magnum to S2-3

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42
Q

What is the name of the middle layer of the menenges that is delicate and nonvascular?

A

Arachnoid mater

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43
Q

When does the arachnoid mater end?

A

S2

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44
Q

What is the name of the innermost layer of the menenges that is delicate, highly vascular and covers the spinal cord?

A

Pia mater

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45
Q

Where is the subarachnoid space located?

A

Between the pia and arachnoid mater which is where CSF resides

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46
Q

What is the function of the CSF?

A

Mechanical buffer to protect the brain and spinal cord

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47
Q

What is the specific gravity of CSF and how does that relate to water?

A

1.003-1.009 slightly greater than that of water (1)

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48
Q

What is the total amount of CSF in an adult and how much of that is in the subarachnoid space?

A

150mL in an adult, 20-35mL is present in the subarachnoid space

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49
Q

How much CSF is produced in a day?

A

21mL/hr which is equivalent to about 500mL/day

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50
Q

What dermatome is represented at the little finger?

A

C8

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51
Q

What dermatome is represented at the nipple line at the 4-5th intercostal space?

A

T4

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52
Q

What dermatome is represented at the level of the xyphoid process?

A

T6

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53
Q

What dermatome is represented at the level of the umbilicus?

A

T10

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54
Q

What dermatome is represented at the level of the posterior medial thigh?

A

S2

55
Q

How can the dermatome C7 be easily identified?

A

Find the most prominent cervical process

56
Q

How can the dermatome T7 be easily identified?

A

Find the inferior tip of the scapula

57
Q

How can the dermatome L4 be easily identified?

A

Find the superior aspect of the iliac crest

58
Q

How can the dermatome S2 be easily identified?

A

Posterior superior iliac spine

59
Q

What is the function of A-alpha nerve fibers?

A

Motor and proprioception

60
Q

What is the diameter and level of myelination in A-alpha nerve fibers?

A

Heavy myelination and 6-22um in diameter

61
Q

What is the function of A-beta nerve fibers?

A

Motor, proprioception, touch and pressure

62
Q

What is the diameter and level of myelination in A-beta nerve fibers?

A

Moderate myelination and 6-22um in diameter

63
Q

What is the function of A-gamma nerve fibers?

A

Muscle tone

64
Q

What is the diameter and level of myelination in A-gamma nerve fibers?

A

Moderate myelination and 4-6um in diameter

65
Q

What is the function of A-delta nerve fibers?

A

Pain, touch and cold

66
Q

What is the diameter and level of myelination in A-delta nerve fibers?

A

Light myelination and 1-4um in diameter

67
Q

What is the function of Beta nerve fibers?

A

Preganglionic and Sympathetic

68
Q

What is the diameter and level of myelination in Beta nerve fibers?

A

Light myelination and 0.5-2um in diameter

69
Q

What is the function of the C nerve fibers?

A

Pain, touch, warm and cold

70
Q

What is the diameter and level of myelination in C nerve fibers?

A

No myelination and 0.5-1.3um in diameter

71
Q

In what order do nerve fibers become blocked?

A

B, C, A-delta, A-gamma, A-beta and A-alpha

72
Q

When can a dural puncture be accomplished?

A

At any level between L2 and S1

73
Q

What is the most common interspaces for a spinal anesthetic?

A

L2-3 or L3-4

74
Q

What direction would a hyperbaric solution tend to favor in a female patient?

A

Cephalad due to wider hips and narrow shoulders

75
Q

What direction would a hyperbaric solution tend to favor in a male patient?

A

Caudal due to wider shoulders and smaller hips

76
Q

What direction would a hyperbaric solution tend to favor in a pregnant female patient?

A

Cephalad, due to wider hips and an increase in abdominal circumference

77
Q

Why shouldn’t the person helping position hold the shoulders?

A

It can rotate the spinal column making it more difficult to insert the needle at an appropriate angle

78
Q

What is the landmark generally located at L4?

A

Intercrestal line “tuffiers line”

79
Q

If using a hypobaric technique for anesthesia of the anus how can the provider tell if they are in the right place since CSF won’t freely flow out?

A

Ask the patient to valsava and the provider should see CSF bubble up through the needle

80
Q

What is a hyperbaric solution?

A

Local anesthetic solution is heavier than CSF

81
Q

How can the provider make a LA hyperbaric?

A

Add glucose to the local anesthetic

82
Q

What is an isobaric solution?

A

Local anesthetic solution has the same specific gravity as the CSF

83
Q

How can the provider make a LA isobaric?

A

Mix LA with CSF (aspirate and allow it to mix)

84
Q

What is a hypobaric solution?

A

Local anesthetic solution is lighter than CSF

85
Q

How can the provider make a LA hypobaric?

A

Mix LA with sterile water

86
Q

What is the specific gravity of CSF?

A

1.003-1.009

87
Q

What is the baricity of plain 0.5% bupivacaine?

A

Hypobaric to isobaric (0.9990-1.0058)

88
Q

What is the baricity of plain 2% Lidocaine?

A

Hyperbaric

89
Q

What is the baricity of plain 10% procaine?

A

Hyperbaric

90
Q

How do hyperbaric solutions disperse when injected?

A

They migrate to the most dependent area of the spine

91
Q

What are the most important factors that influence the level of the spinal?

A

Baricity
Positioning (during injection and immediately after)
Drug dose
Site of injection

92
Q

What is the most easily identifiable interspace?

A

L2-3

93
Q

At what gauge needle and smaller requires an introducer before insertion?

A

25 gauge or smaller

94
Q

Where should the needle be placed within the interspace?

A

Midline of the lower third of the interspace

95
Q

When inserting the needle what two layers are being passed when pops may be felt?

A
Ligamentum flavum (entering the epidural space)
Dura (entered the subarachnoid space)
96
Q

Why is it important to turn the needle once you have entered the subarachnoid space?

A

To ensure your needle has passed completely through the dura

97
Q

When aspirating the CSF what is a clear indicator it is entering the syringe?

A

You will see a swirl in the syringe demarcating a different substance has entered

98
Q

Why is it important to elevate the patients head after insertion of local anesthetic into the subarachnoid space?

A

To prevent a total spinal

99
Q

What type of spinal needle has a higher rate of postdural headaches?

A

Quincke, or a cutting needle

100
Q

What three scenarios may be occurring if bone is being struck while inserting a spinal needle?

A

Needle is touching the superior crest of the spinous process below the interspace
Needle is touching the interior surface of the spinous process above the interspace
Repeatedly encountering bone is probably striking lamina

101
Q

What should the provider do if they encounter paresthesia while inserting a spinal needle and it goes away after a minute?

A

Continue with the injection

102
Q

What should the provider do if they encounter paresthesia while inserting a spinal needle and it does not go away after a minute?

A

Remove and reposition the needle

103
Q

If no CSF flow through the catheter and paresthesia occurs where is the needle most likely located?

A

Extradural

104
Q

What has occurred if there is no CSF, no paresthesia and no bone?

A

May have transversed both the dorsal and anterior surfaces of the dura
Gently aspirate the syringe as you pull the needle back

105
Q

What has occurred if frank red blood that does not clear up is seen when the stylet is pulled from the catheter

A

The tip is likely in an epidural vein

106
Q

What fibers are our goal to block in spinal anesthesia?

A

A-delta and C fibers

107
Q

At what level can the cardio-acclerator center be blocked?

A

T4 resulting in bradycardia

108
Q

How often should the degree of the block be checked when initially setting up?

A

Every 2-3m

109
Q

What sensation should be used to assess dermatome level?

A

Cold temperature

110
Q

Where is the upper limit of the autonomic block in relation to level of sensory block?

A

Two dermatomes higher

111
Q

Where is the upper limit of the motor block in relation to level of sensory block?

A

Generally two dermatomes below

112
Q

What is generally the level of a saddle block?

A

S2-5

113
Q

What is typically the desired level of a low spinal?

A

T10

114
Q

At what level would a tourniquet be able to be used with spinal anesthesia?

A

T4

115
Q

What is considered a high spinal?

A
C8 proper (remember little finger)
However jargon for anything higher than a T2 block
116
Q

What two ligaments does the paramedian approach avoid?

A

Supraspinous and Interspinous ligaments

117
Q

Where does the needle pass in order to bypass the interspinous and supraspinous ligaments?

A

Needle passes through the paraspinal muscles to the ligamentum flavum

118
Q

What type of patients is the paramedian approach beneficial in?

A

When patients cannot flex the lumbar spine : back surgeries, rheumatoid arthritis and hip/leg trauma

119
Q

What opening does the Lumbosacral approach utilize?

A

Uses the largest opening to the spinal canal L5-S1

120
Q

Where should the skin wheal be made for the paramedian approach?

A

1cm lateral and 1cm caudad to the spinous process above the selected interspace

121
Q

Where should the skin wheal be made for the lumbosacral approach?

A

1cm medial and 1cm caudad to the spine

122
Q

what is another name for the lumbosacral approach?

A

Taylor approach

123
Q

How does adding epinephrine effect a block?

A

Prolongs the duration and possibly the intensity of the LA effect

124
Q

How much epinephrine can be added to LA?

A

0.1-0.2mL of 1:1000

125
Q

What LA do vasoconstrictors have the greatest impact on?

A

Tetracaine

126
Q

How much phenylephrine can be added to LA for vasoconstrictive effects?

A

0.05-0.2mL of 1% solution

127
Q

When is clonidine useful to use in spinal anesthesia?

A

Prolong the duration of SAB when epi is contraindicated

128
Q

What central effects can clonidine have when given in SAB?

A

Appears to help prevent tourniquet pain

129
Q

How can the best analgesia be achieved with spinal anesthesia?

A

Combination of preservative FREE opioid and local anesthetic agents

130
Q

What are the most common opioids used in SAB?

A

Fentanyl
Morphine
Sufentanil
Meperidine

131
Q

What is the dose of fentanyl mixed with LA?

A

12.5-25mcg

132
Q

Why is morphine more likely to cause respiratory depression in SAB compared to fentanyl?

A

Highly polarized not highly bound to lipid elements in the spinal cord and feely drifts into CSF

133
Q

What is the dose of Morphine with LA?

A

0.25-0.5mg

134
Q

What complication are seen with opioids used in SAB?

A

Urinary retention
Itching
Respiratory depression