Neuraxial Anesthesia & Local Anesthetic Dosing

Question 1

Descent of the Spinal Cord & Dural Sac

Answer 1

Question 2

Neuraxial Anatomy

(Layers From Skin to CSF)

Answer 2

Question 3

Spinal Vertebrae

Answer 3

Question 4

Spinal Nerve Roots

Answer 4

Question 5

Nerve Roots

Answer 5

Question 6

Spinal/Epidural Landmarks

Answer 6

Question 7

Finding The L3-4 Landmark

Answer 7

Question 8

T10 (Umbilicus) Dermatome

Answer 8

Question 9

T4 (Nipple) Dermatome

Answer 9

Question 10

T5-L1 (Vasomotor Tone) Dermatome

Answer 10

Question 11

T5-L1 (Vasomotor Tone) Dermatome (Cont’d)

Answer 11

Question 12

T1-T4 (Cardiac Accelerator Fibers) Dermatome

Answer 12

Question 13

C3-C5 (Phrenic Nerve) Dermatome

Answer 13

Question 14

C6-C8 (Hands/Fingers) Dermatome

Answer 14

Question 15

C6-C8 (Hands/Fingers) Dermatome (Cont’d)

Answer 15

Question 16

Other Neuraxial Dermatomes

Answer 16

Question 17

Sympathetic vs. Sensory vs. Motor Blockade

Answer 17

Question 18

Sympathetic Blockade

Answer 18

Question 19

Nerves are more easily blocked if they are:

Answer 19

Question 20

Differential Blockade

Answer 20

Question 21

Epidural

Answer 21

Question 22

EpiduralAdvantages

(Compared To Spinals) (4)

Answer 22

Question 23

EpiduralDisadvantages

(Compared To Spinals) (2)

Answer 23

Question 24

EpiduralDisadvantages

(Compared To Spinals) (3-4)

Answer 24

Question 25

“Walking Epidural”

Answer 25

Question 26

Spinal Anesthesia

Answer 26

Question 27

Spinal Needle Options

Answer 27

Question 28

18ga “Introducer Needle”

Answer 28

Question 29

Purpose Of The 18ga Introducer Needle

Answer 29

Question 30

22ga Spinal Needle

Answer 30

Question 31

Common Uses For The 22ga Spinal Needle

Answer 31

Question 32

25ga Spinal Needle

Answer 32

Question 33

27ga Spinal Needle

Answer 33

Question 34

27ga Spinal Needle

Answer 34

Question 35

Continuous Spinal Anesthesia

Answer 35

Question 36

The Problem With Continuous Spinal Anesthesia

Answer 36

Question 37

Continuous Spinal Anesthesia In The US & UK

Answer 37

[https://www.youtube.com/watch?v=z6Ag2tYohRg](https://www.youtube.com/watch?v=z6Ag2tYohRg)

Question 38

Practical Use Of Continuous Spinal Anesthesia

Answer 38

Question 39

Management Of Continuous Spinal Anesthesia

Answer 39

Question 40

Continuous Spinal Anesthesia After Accidental Wet Tap

Answer 40

Question 41

Baricity Of Spinals

Answer 41

Question 42

Hyperbaric Spinal

Answer 42

Question 43

Hyperbaric Spinal For The Supine Position

Answer 43

Question 44

Effect of Glucose on Hyperbaric Spinal for the Supine Position

Answer 44

Question 45

Hyperbaric “Saddle” Block

Answer 45

Question 46

Hypobaric Spinal

Answer 46

Question 47

Isobaric Spinal

Answer 47

Question 48

Combined Spinal Epidural (CSE) Technique

Answer 48

Question 49

“Espocan” CSE Needle

Answer 49

Question 50

Combined Spinal Epidural (CSE) Advantages (3)

Answer 50

Question 51

Combined Spinal Epidural (CSE) Disadvantage (1)

Answer 51

Question 52

Dural Puncture Epidural Technique | (A New Form of Continuous Spinal Anesthesia?)

Answer 52

Question 53

Dural Puncture Combined Spinal Epidural Technique

Answer 53

1. An epidural needle is placed 2. A spinal needle is inserted through the Tuohy needle and punctures the dura 3. The spinal needle is removed without dosing intrathecal medication –This leaves a small hole in the dura 4. The epidural catheter is placed and hooked up to an infusion pump 5. The local anesthetic primarily goes into the epidural space, but a small portion is allowed to “leak into” the intrathecal space through the hole that was created by the spinal needle –This technique allows faster sacral onset and greater sacral spread of the local anesthetic, and it results in a lower incidence of unilateral block

Question 54

Dural Puncture Epidural Technique Advantages (3)

Answer 54

Question 55

Dural Puncture Epidural Technique Disadvantage (1)

Answer 55

Question 56

Epidural vs. Spinal Dosing Summary

Answer 56

Question 57

Caudal Anesthesia Landmarks

Answer 57

Question 58

Caudal Anesthesia

Answer 58

Question 59

Caudal Technique Video

Answer 59

[https://www.youtube.com/watch?v=9cR2Co\_H400](https://www.youtube.com/watch?v=9cR2Co_H400)

Question 60

Caudal Technique

Answer 60

1. Palpate the sacral hiatus - This is covered by the sacrococcygeal ligament - It is above the coccyx and between the sacral cornu (bony prominences lateral to the sacral hiatus) 2. Insert the needle through the sacral hiatus at a 45° angle 3. Advance cephalad until a “pop” is felt 4. Advance the cannula over the needle and remove the needle 5. Aspirate before injecting

Question 61

Lumbar Epidurals

Answer 61

When epidurals are performed in the lumbar or thoracic region, it is possible for the needle to cause spinal cord or nerve root damage, due to the proximity of the spinal cord and nerve roots -Therefore, when epidurals are performed in the lumbar or thoracic region, **it is vital that the patient be awake** (so that they can alert the anesthetist of any parasthesias) to reduce the chance of nerve injury

Question 62

Caudal Epidurals

Answer 62

Question 63

Epidural Blocks In Children

Answer 63

Question 64

Advantages of Caudal Anesthesia (3)

Answer 64

Question 65

Disadvantages of Caudal Anesthesia (5)

Answer 65

Question 66

Caudal Anesthesia in Adults?

Answer 66

Question 67

Factors Affecting The Neuraxial Spread Of Local Anesthetics (7)

Answer 67

* *1. Total mg dose** - Higher doses spread more than lower doses * *2. Total volume injected** - 10mL 1% lidocaine (100mg) will spread more than 1mL 10% lidocaine (100mg) * *3. Addition of epi** - Prolongs the block, but doesn’t raise the block level * *4. Addition of narcotic** - Increases the density (“strength”) of the block 5. Height of the patient (more so than weight) - The shorter you are, the more likely the block will travel “too high” * *6. Positioning** - Trendelenburg = more cephalad spread of local anesthetic - Reverse Trendelenburg = less cephalad spread of local anesthetic - Lateral: the block will be more one sided * *7. Weight of the patient** - The more obese (heavy) the patient: - The further (higher) the local anesthetic will spread - The lower the local anesthetic dose requirement

Question 68

Why would obese patients/or twin pregnancies have an increased chance of a high block?

Answer 68

Question 69

Duration of Neuraxial Blocks in the Elderly

Answer 69

Question 70

Summary Of Onset, Duration, & Dosing For Neuraxial Blocks In Elderly Patients

Answer 70

Question 71

Absolute Contraindications to Neuraxial Anesthesia (8)

Answer 71

**1. Patient refusal** **2. Infection at the injection site** (because a block could lead to possible meningitis or an epidural abscess) **3. Severe hypovolemia** (because there’s a good chance that the patient wouldn’t be able to tolerate the sympathectomy) **4. Coagulopathy** (could lead to a possible epidural hematoma) 4a. Thrombocytopenia In OB, platelet counts \>80,000-100,000 are generally considered safe prior to neuraxial blockade (Protocols for High-Risk Pregnancies, 5th edition, page 169) 4b. Elevated PT/PTT/INR * *5. Severe aortic stenosis** - Sympathectomy drops preload & afterload, and preload/afterload should be maintained with aortic stenosis * *6. Severe mitral stenosis** - For the same reason as aortic stenosis * *7. Sepsis** - Could lead to meningitis **8. Elevated intracranial pressure (ICP)** -These patients can’t tolerate the sympathectomy because a high MAP is required to perfuse the head in patients with intracranial hypertension (Cerebral perfusion pressure = MAP – ICP)

Question 72

Complications from Neuraxial Blocks (11)

Answer 72

Question 73

Relative Contraindications To Neuraxial Anesthesia (4)

Answer 73

Question 74

Diagnosing Back Pain

Answer 74

Question 75

Epidural Abscess

Answer 75

Question 76

Epidural Hematoma

Answer 76

Question 77

Transient Neurologic Symptoms (TNS)

Answer 77

Question 78

Cauda Equina Syndrome (CES)

Answer 78

Question 79

Post Dural Puncture Headache (PDPH)

Answer 79

Question 80

If an anesthetist accidentally wet taps a patient, they have two options:

Answer 80

Question 81

The symptoms of post dural puncture headache

Answer 81

Question 82

The incidence of post dural puncture headache

Answer 82

Question 83

Treatment For Post Dural Puncture Headache (PDPH) (3)

Answer 83

* *1. Autologous blood patch** - “Epidural blood patch (EBP) is currently the gold standard for PDPH treatment, with a success rate ranging from 90% to 99%” - This should not be attempted until all signs show that the local anesthetic has worn off. Blood patch attempts prior to local anesthetic wearing off have been associated with total spinal anesthesia ([https://www.youtube.com/watch?v=F-MOX3fELGU](https://www.youtube.com/watch?v=F-MOX3fELGU)) **2. Analgesics, caffeine, and generous fluid administration** have also been used to treat PDPH **3. Neostigmine and Atropine combination?** “While neostigmine cannot cross the blood–brain barrier, it passes the choroid plexus, and together with atropine, both affect the CSF secretion and the cerebral vascular tone, contributing in improving PDPH”

Question 84

Regional Anesthesia Advantages (compared to GA) (4)

Answer 84

Question 85

Esters vs. Amides

Answer 85

Question 86

Local Anesthetics with Epinephrine

Answer 86

Question 87

Tetracaine (Pontocaine)

Answer 87

Question 88

Most Common Local Anesthetics For Labor Epidural Dosing (4)

Answer 88

Question 89

Marcaine (Usually Diluted to 0.1-0.25%) Advantages

Answer 89

Question 90

Marcaine (Usually Diluted to 0.1-0.25%) Disadvantages (3)

Answer 90

Question 91

Marcaine Toxic Dose & Reversal Of Toxicity

Answer 91

Question 92

Ropivacaine (Naropin) 0.2%

Answer 92

Question 93

Lidocaine (2% or 1.5% with Epi) Advantages (2)

Answer 93

Question 94

Lidocaine (2% or 1.5% with Epi) Disadvantages (2)

Answer 94

Question 95

Lidocaine (2% or 1.5% with Epi) Disadvantageous Neurological Effect

Answer 95

Question 96

Chloroprocaine (Usually 3%) Advantages (2)

Answer 96

Question 97

Chloroprocaine (Usually 3%) Disadvantages (3)

Answer 97

Question 98

Epidural Bolusing

Answer 98

Question 99

Prior to bolusing through an epidural catheter, the CAA should:

Answer 99

Question 100

Initial Epidural Test Dose

Answer 100

Question 101

Epidural Loading Dose

Answer 101

Question 102

Dose To Increase The Density Of The Epidural Block

Answer 102

Question 103

Raising The Epidural Block Level Gradually

Answer 103

Question 104

Raising The Epidural Block Level Immediately

Answer 104

Question 105

Best choice for emergency C-sections?

Answer 105

Question 106

Preservatives in Local Anesthetics

Answer 106

Question 107

Parabens (i.e. Methylparaben)

Answer 107

Question 108

Parabens (i.e. Methylparaben) contraindications?

Answer 108

Question 109

Sulfites (Bisulfite or Metabisulfite)

Answer 109

Question 110

Are sulfites safe for epidurals and spinals?

Answer 110

Question 111

EDTA

Answer 111

Question 112

Conclusion for spinals and epidurals

Answer 112

Question 113

Preservatives In Bier Block Local Anesthetics

Answer 113

Question 114

Bicarbonate

Answer 114

Question 115

Alpha Agonists

Answer 115

Question 116

Duramorph

Answer 116

Question 117

Advantages of Neuraxial Opioids

Answer 117

Question 118

Disadvantages of Neuraxial Opioids

Answer 118

Question 119

Epidural vs. Spinal Opioids

Answer 119

Question 120

Drug Ionization

Answer 120

Question 121

Placing An Acidic Drug In A More Basic Environment

Answer 121

Question 122

Placing A Basic Drug In A More Acidic Environment

Answer 122

Question 123

Placing A Drug In An Ideal pH Environment

Answer 123

Question 124

pKa of a Drug

Answer 124

Question 125

How would you speed up the onset time of a local anesthetic in the following example?

Answer 125

Question 126

Acidic Drugs (pH \< 7.4) in Basic Environment

Answer 126

Question 127

Acidic Drugs (pH \< 7.4) in Acidic Environment

Answer 127

Question 128

Basic Drugs (pH \> 7.4) in Acidic Environment

Answer 128

Question 129

Basic Drugs (pH \> 7.4) in Basic Environments

Answer 129

Question 130

pKa of Acidic & Basic Drugs

Answer 130

Question 131

Summary Of How pH Relates to pKa

Answer 131

Question 132

Adding bicarb to the local anesthetic will?

Answer 132

Question 133

Local Anesthetics Containing Epinephrine

Answer 133

Question 134

Question

Answer 134

Question 135

Question

Answer 135

Question 136

Factors That Determine Local Anesthetic Onset (4)

Answer 136

* *1. How ionized the local anesthetic is** - The higher the ionization, the slower the onset * *2. How close the local anesthetic’s pH is to the local anesthetic’s pKa** - The closer the local anesthetic’s pH is to pKa, the less ionization, and the faster the onset * *3. How close the local anesthetic’s pKa is to physiologic pH** - The closer the local anesthetic’s pKa is physiologic pH, the less ionization, and the faster the onset **4. How lipid soluble the local anesthetic is**

Question 137

Factors That Determine Local Anesthetic Potency (3)

Answer 137

Question 138

Table Summary Of The Effects Of Lipid Solubility

Answer 138