Exam 1 - Neuraxial Principles I Flashcards
(100 cards)
1
Q
Surgical indications for spinals and epidurals?
A
- Surgeries involving the lower abdomen, perineum, and lower extremeties
- Ortho procedures (hips and knees)
- LE vascular procedures
- Adjunct to GETA during thoracic
2
Q
Neuraxial anesthesia can reduce:
A
- Post op ileus
- Thrombotic events
- PONV
- Resp complications
- Bleeding
- Narcotic usage
3
Q
Other benefits of using neuraxial anesthesia?
A
- Improved mentation
- Less uriniary retention
- Quicker PACU discharge
- Quicker to eat, void, and ambulate
- Blunts surgical stress response
4
Q
What are the relative contraindications to neuraxial anesthesia?
A
- Deformities of spinal column (scoliosis and ankylosing spondylitis)
- Pre-existing disease of spinal cord (MS, post polio syndrome)
- Chronic headache/backache
- Inability to perform SAB/epidural after 3 attempts
5
Q
What are the absolute contraindications to neuraxial anesthesia?
A
- INR > 1.5
- PLT < 100k
- PT, aPTT, and BT 2x normal
- Taking anticoagulants
- Pt refusal
- Severe or critical valvular disease (AS or MS < 1 cm2)
- Prolonged operation (can use CSE)
- Severe CHF ( EF < 30-40%)
6
Q
What are the normals for PT, aPTT, INR, BT, and PLT?
A
PT = 12-14 s
INR = 0.8 - 1.1
aPTT = 25-32 s
BT = 3-7 mins
PLT = 150k - 300k
7
Q
What drugs/tests affect intrinsic pathway?
A
- Heparin
- PTT
- ACT
8
Q
What drugs/test affect the extrinsic pathway?
A
- Coumadin
- PT
- INR
9
Q
Why are we so concerned about using anesthesia on patients with aortic stenosis?
A
DEATH SPIRAL
Hypotension → Myocardial ischemia → Contractile dysfunction → ↓ CO → Increased ischemia
10
Q
Average survival rates in aortic stenosis after onset of severe symptoms of angina, failure, and syncope?
A
Angina = 5 years
Syncope = 3 years
Failure = 2 years
11
Q
Fill in this chart
A
12
Q
Describe the differences between duration and placement of spinal vs epidural?
A
Duration: Spinal: limited and fixed Epidural: Unlimited
Placement level: Spinal: L3-L4, L4-L5, L5-S1 Epidural: Any level
13
Q
What is dosing based upon for spinals and epidurals?
A
Spinals: Dose based (mg), usuall 3-4 cc
Epidurals: Volume-based
14
Q
Which neuraxial technique can cause LAST and how?
How can this be mitigated?
A
- Epidural, injection of LA into dural vein
- Give a test dose
15
Q
How are spinals and epidurals affected by gravity?
A
Spinals: Gravity influences baracity
Epidurals: Gravity influences positioning
16
Q
How is the dermatome spread manipulated in spinals?
A
In the first 5 minutes the spread is affected by position changes and baracity of the drug
17
Q
How is the dermatome spread manipulated in epidurals?
A
Spread is influenced by incremental dosing of volume of anesthetic.
1-2 mL of anesthetic per dermatome segment.
18
Q
What does a wet tap mean?
A
Unintentional puncture of the dura mater.
Can lead to a dural headache.
19
Q
How many vertebrae are there?
How are they arranged?
A
33 total
7 cervical
12 thoracic
5 lumbar
5 fused sacral
4 fused coccyx
20
Q
What vertebrae does not have a body?
A
C1
21
Q
What connections form the vertebral foramen? What is housed in the vertebral foramen?
A
- Connection of the lamina and pedicle
- Spinal cord
21
Q
What is the anatomical marker to ensure medial insertion of a spinal block?
A
Spinous process
22
Q
What are the surface landmarks for spinal anesthesia?
A
Superior iliac crest = L4, this is called Intercristal or Tuffier’s line
Posterior superior iliac spine = S2
23
Q
What population do we mostly do caudal anesthesia?
A
Pediatrics
24
Why are we able to inject anesthetics into the sacrum?
Because the lamina of S5 is incomplete and bridged only by ligaments, allowing injection into the sacral hiatus
25
What type of anesthesia is caudal?
Epidural because there is no CSF below the dural sac
26
What is the name for the end of the spinal cord and what level does it occur in adults and infants?
- Conus medullaris
- Adults: L1
- Infants: L3
27
What is the cauda equina and where is it located?
- Bundle of nerve roots from L2-S5 and coccygeal nerve
- Extends from conus medullaris to dural sac
28
How many nerves per vertebral level?
2, a right and left
29
What is the dural sac?
Where is it located for adults and infants?
- Marks the ending of the subarachnoid space
- Ends at S2 in adults and S3 in infants
30
The anterior spinal artery perfuses ____ of the spinal cord and supplies the ____ portion
2/3
Motor (anterior)
31
The posterior spinal arteries (2) supply blood to the ____ portion
Sensory (posterior)
32
What are the 3 ligaments from surface to deep, that are pentrated during neuraxial anesthesia?
Supraspinous
Interspinous
Ligamentum Flavum
33
Layers punctured in order during midline approach?
Skin
Subcutaneous fat
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Dura Mater
Subdural space
Arachnoid Mater
Subarachnoid space
## Footnote
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34
Layers punctured in order during paramidline approach?
Skin
Subcutaneous fat
Ligamentum flavum
Dura Mater
Subdural space
Arachnoid Mater
Subarachnoid space
## Footnote
Some Students Leave Declaring Spinals Are Stupid
35
When would you use the paramedian approach?
The patient cannot flex their spine (scoliosis)
36
What a potential space?
What are the potential spaces in the spine?
A space that has the *potential* to contain air or fluid
Subdural space and epidural space
37
What is contained in the epidural space?
Fat and epidural veins
38
What is contained in the subarachnoid space?
CSF
39
If you get blood return during an epidural, what does that mean?
You are likely lateral, since the density of veins increases laterally in the spinal column
40
What is another name for the epidural veins?
Batson's Plexus
41
What is the landmark for caudal anesthesia in pediatrics?
Sacral Cornu
42
How could you tell if you punctured a dural vein during epidural placement?
There would be continous blood flow
43
This structure is a band of connective tissue between the ligamentum flavum and dura mater and can act as a barrier - leading to unilateral blockade?
Plica Mediana Dorsalis
44
These three things are contained within the subarachnoid space?
CSF, nerve roots, and spinal cord
45
Effects of injecting LA into the subdural space during an epidural and spinal?
**Epidural:** could cause "high spinal" effect
**Spinal:** failed spinal block - no anesthetic effect
46
Meningeal layers from out to in?
Dura, arachnoid, pia
47
This meningeal layer has an important role of reabsorbing the local anesthetic?
Pia mater
48
Total *pairs* of spinal nerves?
How are they arranged?
31
C1- C7: nerves exit *above* the vertebrae
C8: exits below C7
Thoracic 12
Lumbar 5
Sacral 5
Coccycx 1
49
What is the dermatomal level for the clavicles?
C5
50
What is the dermatome(s) responsible for the lateral parts of the upper limbs?
C5, C6, C7
51
The thumb and hand are in what dermatomes?
Thumb: C6
Hand: C6,7,8
52
What dermatomes are the medial sides of the upper limbs in?
Ring and little fingers?
Medial sides of upper limbs: C8, T1
Ring and little fingers: C8
53
The cardiac accelerator nerves are comprised of:
Nerves originating from T1-T4
54
The level of the nipples corresponds to this dermatome:
T4
55
The umbilicus corresponds to this dermatome:
T10
56
T12 dermatome includes sensation for:
Inguinal and groin regions
57
What dermatomes provide sensation to the anterior and inner surface of the lower limbs?
L1,2,3,4,5
58
What dermatomes are the feet in?
L4,5, S1
59
What dermatome is the medial side of the great toe in?
Lateral margin of foot and little toe?
Medial great toe: L4
Lateral foot and little toe: S1
60
L5, S1,2 dermatome provides sensation to:
Posterior and outer surface of lower limbs
61
The perineum is in what dermatome?
S2,3,4
62
This facial nerve and its branches are crucial when providing an airway block?
Trigeminal
- V1: opthalmic
- V2: Maxillary
- V3: Mandibular
63
Give the dermatomes for the follwing surgeries:
* Peri-anal/anal (saddle block)
* Foot/ankle
* Thigh/lower leg/ knee
* Vaginal/uterine/hip/tourniquet/TURP
* Scrotum
* Penis
* Testicular
* Urologic/GYN/Lower abdominal
* Cesaren/upper abdomen
64
List the 7 factors that affect the spread of LA in spinals
- Baricity
- Patient position
- Dose
- Site of injection
- Volume of CSF
- Increased abdominal pressures (pregnant, obese)
- Elderly age
65
What is the most reliable factor to predict spread of a spinal?
Dose, only when using hypo-or hyperbaric solutions
66
What does low CSF volume do the spinal spread?
Who has low CSF volume?
- Low CSF volume leads to extensive spread of LA intrathecally
- Elderly and pregnancy (increased abdominal pressure)
67
These 5 factors do *not* affect the spread of spinal:
- Barbotage (repetated aspiration and injection of CSF)
- Speed of injection
- Orientation of bevel
- Added vasoconstrictors
- Gender
68
What **significantly** affects the spread of epidural LA?
- LA volume (most important)
- Level of injection
- LA dose
- Pregnancy
- Old age
69
What has a **small affect** on epidural LA spread?
- LA concentration
- Patient position
- Height
70
What has **no** affect of epidural LA spread?
- Additives (may change onset or duration)
- Bevel direction
- Speed of injection
71
What are the spread dynamics for epidurals placed cervical, thoracic, and lumbar?
Cervical - spreads caudad
Thoracic - balanced spread
Lumbar - mostly spreads cephalad
72
Match the nerve to its function:
- B
- C
- A-delta
- A-gamma
- A-beta
- A-alpha
- B: autonomic preganglionic fibers (venodilation/hypotension)
- C: pain and temperature
- A-delta: pain and temperature
- A-gamma: motor tone
- A-beta: touch and pressure
- A-alpha: motor and proprioception
73
What is the order in which different nerve types are blocked?
Why?
- B, C, A-delta, A-gamma, A-beta, A-alpha
- Because of the arrangement inside the nerve bundle. Blockade occurs from outside to inside
74
What is the order in which nerves recover?
Which nerve is blocked the longest?
- Reverse of block onset: A-alpha, A-beta, A-gamma, A-delta, C, B
- B fibers are blocked the longest
75
What are the differential blockade zones?
**Sensory level:** 2 above motor level
**Sympathetic:** 2-6 above sensory level
76
If a spinals sensory blockade is at the level of T8, what is the level of sympathetic block?
What does this mean?
- T2-T6
- The cardiac accelartator nerves are blocked and you will see CV effects - **HAVE EMERGENCY MEDS PREPPED**
77
What is the order of loss of sensations?
How are they monitored?
- Temperature, then pain, then touch/pressure
- Temperature: alcohol pad
- Pain: pinprick
- Touch/pressure: push on tissue
78
What scale is used to monitor lower motor blockade?
What are the levels?
- Modified Bromage Scale
- 0 to 3, 0 is no block and 3 is complete motor block (cannot move legs, feet, or knees)
79
What are the CV effects of neuraxial anesthesia?
Decreased preload, afterload, CO (may increase initially), and HR leading to hypotension caused by venodilation from sympathectomy
80
What causes the decreased CO from neuraxial anesthesia?
Decreased venous return and SVR leading to decreased SV
81
What reflexes can decrease the HR after neuraxial anesthesia?
- Reverse bainbridge: triggered by decreased stretch of RA
- Bezold-Jarisch Reflex: due to ventricular underfilling - mediated by 5HT3 receptors in vagus nerve and ventriular myocardium
82
What drug and dose can help to prevent the Bezold-Jarisch reflex?
8 mg of Ondansetron - 5HT3 antagonist
83
How can you prophylactically treat the CV effects from neuraxial anesthesia?
- Pressors (phenylephrine gtt)
- Co-loading fluid
- Positioning (LUD in pregnancy)
- Ondansetron
84
How much fluid should be administered if you decide to co-load fluids during spinal-anesthesia?
~ 15 mL/kg
85
How can treat spinal-induced hypotension after spinal administration?
- Pressors (ephedrine or epi, based on HR)
- Anticholinergics (atropine/glyco)
- Fluids
- Positioning
86
Why should you caution when changing patient position to treat spinal induced hypotension?
- Trendelenberg can lead to increase venous return, but >20 degrees will reduce cerberal perfusion d/t decreased cerebral venous drainage
- If the block hasn't set up yet, the bock height will increase d/t gravity
87
Why is treating spinal induced hypotension important?
Failure or delay in treatment will increase mortality
88
Pulmonary effects of neuraxial anesthesia?
- ERV decreases
- VC decreases
| Minimal overall effects
89
What populations should be cautioned when using neuraxial anesthesia d/t the pulmonary effects?
- COPD
- Pickwickian syndrome (Obesity hypoventilation syndrome)
90
Interventions if someone becomes dyspneic after spinal anesthesia?
- Semi-fowlers position
- Caution giving O2 unless hypoxic, can increase feelings of dyspnea
91
Sympathetic and parasympathetic innervation for the GI system?
Parasympathetic: vagus nerve
Sympathetic: nerves from T5-L2
92
GI effects from neuraxial anesthesia?
- Reduced sympathetic tone and increased parasympathetic tone
- Sphincters relax
- Increased peristalsis
- Increased GI blood flow
- Reduced post op ileus in abd surgery
93
Why do patients typically need a Foley catheter with neuraxial anesthesia?
At what level is bladder control affected?
* Causes urinary retention and incontinence from increased PNS tone
* Blockade above T10 affects bladder control
94
Metabolic/endocrine effects from neuraxial anesthesia?
Supression of neuroendocrine response
Prevents increase in cortisol, catecholamines, and activation of the RAAS
95
Describe the basic structure of LA and their water solubility?
Aromatic ring: Lipophilic
Tertriary amine: Hydrophilc
Intermediate chain: determines drug class
96
What could cause allergic reactions to local anesthetics?
Esters: PABA - para-aminobenzoic acid
Amides: methylparaben
| Preservatives
97
What determines the onset, potency, and duration of LA?
Onset: pKa
Potency: Lipid solubilty
Duration: protein binding (⍺1-acid glycoprotein)
98
What 5 factors affect vascular uptake and plasma concentration of LA?
- Site of injection
- Tissue blood flow
- Physiochemical properties
- Metabolism
- Addition of vasopressor
99
List the site of injections from high to low in regards to LA plasma concentrations?
- IV
- Tracheal
- Intercostal
- Caudal
- Paracervical
- Epidural
- Brachial
- Sciatic
- Subcutaneous
## Footnote
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