Reg 2 Flashcards
(202 cards)
1
Q
Local anesthetics
A
Drugs used to produce reversible conduction blockade of impulses along central and peripheral nerve pathways
2
Q
Regional anesthesia
A
insensibility of a part induced by interrupting the sensory nerve conductivity of that region of the body
The result of a conduction blockade of specific peripheral nerves or nerve groups
3
Q
Esters:
A
Are less stable (shorter shelf life)
Metabolized in the plasma by pseudocholinesterases
More prone to cause allergic reactions
4
Q
Amides
A
More stable
Metabolized by liver
Rare allergies
5
Q
SPINAL
A
Small volume
Direct-Sheath
Rapid onset
Total neural block-both sensory and motor
6
Q
Epidural/PNB
A
Large volume
Outside-Sheath
Slow onset
Block varies with dose
7
Q
PERIPHERAL vs. CENTRAL
advantages
A
Segmental block Slow onset = time to Rx side effects Flexibility in density Flexibility in duration Less side effects
8
Q
PERIPHERAL vs. CENTRAL
disadvantages
A
More technical & more failure
More time consuming
Greater LA volume- [>toxicity risk]
Faulty block
9
Q
Definition spinal
A
It is the reversible chemical blockade of neuronal transmission produced by injection of a LA into the CSF contained in the subarachnoid space
10
Q
goal of spinal
A
Render patient insensitive to surgical stimuli while producing minimal physiologic alteration
11
Q
Types neuraxial anesthesia
A
Spinal
Epidural
Caudal: similar to epidural. But in sacrum. Kids only
12
Q
neuraxial uses
A
Alternative to general anesthesia
Can be used in conjunction with GA
Post-operative analgesia: may use lower opioid use with and decreases incidence of atelectasis, hypoventilation, and aspiration pneumonia
Management of acute or chronic pain
13
Q
advantages and system improvements with neuraxial
A
- Sympathectomy-mediated increases in tissue blood flow
- Improved oxygenation from decreased splinting
- Enhanced peristalsis
- Suppression of the neuroendocrine stress response
14
Q
advantages spinal anesthesia
A
- Simple
- Predictable
- Fully conscious patient
- Analgesia into the post-op period
- Ideal for lower abdomen, pelvis/ perineum, and lower extremities
- Reduces risk of DVT
- Use small dose of LA, less toxicity
15
Q
Disadvantages spinal anesthesia
A
-Sympathetic blockade 100% of the time =Hypotension -Intense motor blockade =May last for hours post-op -Surgeons complain “It takes too long
16
Q
Absolute Contraindications
A
-Patient refusal
-Severe psychiatric disease:
May not cooperate
-Infection at the site
-Septicemia or bacteremia
17
Q
Absolute Contraindications: cardiovascular
A
Cardiovascular disease:
-Severe aortic/mitral stenosis and septal hypertrophy
18
Q
Absolute Contraindications: Fluid status
A
Severe hypovolemia:
- Can be corrected before the spinal
- Pt in shock
19
Q
Absolute Contraindications CNS
A
CNS disease:
- MS or nerve injury
- Herpetic infections
- Increased ICP- brain herniation
20
Q
Absolute Contraindications: allergies
A
Allergy to LA:
- Ester LA
- Reaction to the preservatives
21
Q
Absolute Contraindications: blood
A
Blood clotting anomalies:
-Anticoagulant therapy
ASRA guidelines
22
Q
relative Contraindications
A
-HIV: Associated with neurological manifestations -Surgery of unknown duration -Untreated chronic HTN: *Unstable BP after spinal *Greater drop in BP than normal pt -Procedures above the abdomen -Obesity
23
Q
relative Contraindications
A
- Deformities of the spinal column
- Chronic HA or backache
- Bloody tap
- Multiple attempts
24
Q
relative contraindication : blood clotting
A
- Minor abnormalities in blood clotting:
- ASA therapy
- Small dose of heparin
- Check coags before spinal insertion and document
- Risk for spinal hematoma
- Platelet count
25
pros and cons for Sick Elderly Patient
-PROs
*Possibility of less post-operative delirium
-CONs
*Hypotension, bradycardia
Rebound HTN, tachycardia = Fluid & pressors
26
pros for OB pt
Decreased M&M
| Less effects on mother and fetus
27
Informed Consent
- Make sure you document you have discussed the advantages and disadvantages with the patient and alternative techniques
- Make sure pt knows that spinals sometimes do not work
* May need to convert to a GA
- Make sure patients understands and accepts risk
- Document the informed consent
28
Vertebral Column
- 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused) vertebra
* Differ in shape and size according to level
- The vertebral bodies are connected by the intervertebral disks
29
Spinal column forms a ...
DOUBLE C
30
Ligamentous elements provide ...
structural support.
Along with muscles help maintain shape
31
Ventrally –
- Motor
| - Vertebral bodies and intervertebral disks are connected + supported by anterior and posterior longitudinal ligaments
32
Dorsally –
- Sensory
| - LF, ISL, SSL provide additional stability
33
spinal canal layers
- ligamentum flavum
- epidural space (potential)
- dura mater
- subdural space (potential)
- arachnoid mater
- subarachnoid space
- pia mater
- meninges-cover the spinal cord
- spinal cord
34
spinal cord Extends from
- foramen magnum to L1 in adults
| - L3 in children
35
Anterior & posterior nerve roots at each spinal level join one another and ...
exit the intervertebral foramina forming spinal nerves from C1 to S5
36
Where does the SC end?
L1Adults
37
where does dural sac end?
S2
38
Cervical level in relation to nerves
nerves arise above their perspective vertebrae hence 8 nerve roots
39
Thoracic level in relation to nerves
nerves exit below
40
Below L1 =
- lower spinal nerves form the cauda equina
- Usually avoid potential needle trauma because these nerves float in the dural sac below L1 and tend to be pushed away rather than pierced
41
Largest intervertebral space is ...
| Thickest is...
Largest intervertebral space is L4-5
| Thickest is T1
42
Blood supply to spinal cord
- Single anterior spinal artery:
* Formed from vertebral artery at the base of the skull
* Course down the anterior surface of the cord
* Supplies the anterior 2/3 of the cord
43
Paired posterior spinal arteries
- Arise from the posterior inferior cerebellar arteries
- Course down along the dorsal surface of the SC medial to the dorsal nerve roots
- Supplies the posterior 1/3 of the cord
44
Additional blood flow to the arteries from the
intercoastal arteries
45
artery of adamkiewicz or arteria radicularis magna
- arising from the aorta
Typically unilateral and nearly always arises on the left side, providing the major blood supply to the anterior lower 2/3 rds of the spinal cord = injury here results in anterior spinal artery syndrome
Must be more careful with anterior
46
Principal site of action for neuraxial blockade is the ...
nerve root
| LA bathes the nerve roots in subarachnoid space or epidural space
47
Blockade of neural transmission (conduction) in the posterior nerve root fibers interrupts
somatic and visceral sensation
48
Blockade of anterior nerve root fibers prevents
efferent motor and autonomic outflow
49
Sensory blockade –
somatic + visceral
50
Smaller and myelinated fibers vs larger unmyelinated fibers
Smaller and myelinated fibers are generally more easily blocked than larger unmyelinated fibers
51
differential blockade
Because the concentration of LA decreases the further away from the injection site
52
Dermatome Sensory BlockadeRule of TWO (2)
Sympathetic blockade 2 segments higher than sensory blockade which is 2 segments higher than motor blockade
53
Classifications of nerve Fibers bloackade-
small myelinated get blocked 1st, then small to large fibers
54
sympathetic blockade
T8, temperature
55
Sensory blockade
T10, pin prick
56
Motor blockade
T12
57
T4 blockade
will get bradycardia
58
Cervical segments
C5- Anterolateral shoulder
C6- Thumb
C7- Middle finger
C8- Little finger
59
Thoracic segments
```
T1- Medial arm
T3- 3rd, 4th interspace
T4- Nipple line, 4th, 5th interspace
T6- Xiphoid process
T10- Navel
T12- Pubis
```
60
Lumbar segments
L2- Medial thigh
L3- Medial knee
L4- Medial ankle
L5- Dorsum of foot
61
Sacral segments
S1- Lateral foot
S2- Posteromedial thigh
S3,4,5- Perianal area
62
Order of Nerve Fiber Blockade
- B fibers-Autonomic, sympathetic efferent
- C and A Delta Temperature, Touch
- A Gamma- muscle tone
- A Beta- small motor, pressure
- A Alpha- Large Motor, Proprioception
* This is the order for motor blockade
63
Due to small size autonomic fibers are
blocked quickly
64
Sympathectomy is accentuated in
the hypovolemic pt
65
earliest sign that spinal is working
Drop in BP is the earliest sign that the spinal is working
A rapid drop in BP may cause nausea and dizziness
Treat quickly
66
Temperature and Light Touch
- Innervated by the unmyelinated C and myelinated A-delta fibers
- Loss of these follows autonomic blockade
67
how to assess temp and light touch?
alcohol swab
68
Loss of temperature correlates with
sensory loss
69
Motor Impairment & Touch
Myelinated A-beta & A-gamma
70
Loss of motor & touch follows loss of
light touch and temperature discrimination
71
Differential block
| Motor block is
2 dermatones below sensory block
72
Profound Motor Block
Myelinated A-alpha
73
Motor block and loss of propioception
Pt’s will feel legs are still in the air after being prepped
74
Assess block
| S1-2-
S1-2- dorsiflex his feet
75
Assess block
| L4-5- flex his toes
flex his toes
76
Assess block
| L2-3-
raise his knees
77
Assess block
| T6-T12-
lift shoulders off the bed
78
S2-5
- Saddle block
- No affect on the ANS
- Surgical anesthesia limited to perineum, perianal, & genitalia
79
T10 (umbilicus)
- Low spinal
- Blocks S1-5 & L1-5
- Produce vasodilation, lower BP
- Good for GYN, vaginal delivery, lower extremity surgery, TURP, & cysto
80
T4 (nipple)
- High spinal
- Used for upper abdominal surgery
- Can feel traction
- Can cause vasodilation and block cardioaccelator fibers
81
C8 (little finger)
- Total spinal
- Difficulty breathing
- Can lead to respiratory & cardiac arrest
82
Cardiac Manifestations of Neuraxial Blockade
- ↓ BP, ↓ HR, ↓ Contractility – all proportionate to the level of sympathectomy
- Vasomotor tone arises from T5-L1 – innervates arterial and venous smooth muscle
* Vasodilation
* Decreased venous return to heart
* May decrease SVR
83
REMEMBER the cardiac accelerator fibers that arise from T1-T4
REMEMBER the cardiac accelerator fibers that arise from T1-T4
84
CV effects prevention:
- Loading fluid bolus 10-20ml/kg
- LUD (pregnancy)
- Trendelenbug
- Medications:
* ATROPINE
* EPHEDRINE OR PHENYLEPHRINE
* EPINEPHRINE ( last resort)
85
Pulmonary Manifestations of Neuraxial Blockade
- Usually minimal effects
* Small decrease in VC due to loss of abdominal muscle contribution
- Diaphragm innervations C3-4-5
* Even with total spinal phrenic nerve may not be blocked
* Apnea should resolve after resuscitation
- BEWARE in patients with limited respiratory reserve
* Accessory muscles NEEDED
86
GU Manifestations of Neuraxial Blockade
- Little effect on renal BF
| - Loss of control of bladder function = urinary retention with bladder distention
87
GI Manifestations of Neuraxial Blockade
- Sympathetic outflow originates T5-L1
* Vagal tone dominance = small contracted gut with active peristalsis
- Hepatic blood flow decreases with MAP
88
Metabolic and endocrine Manifestations of Neuraxial Blockade
- Surgery causes neuroendocrine response
- Neuraxial anesthesia can partially supress or totally block responses
- Decreases catecholamine release
- May reduce perioperative arrhythmias and ischemia
89
Neuraxial Blockade and Anticoagulation
Oral Anticoagulants (Warfarin) :
- Check PT/INR
- Stopped 4-5 days prior
- If only one dose was given within 24 hours of block – it is safe to proceed
- Epidural removal in low dose warfarin (5 mg/d)
90
Neuraxial Blockade and Antiplatelet Agents
Antiplatelet Drugs :
- ASA & NSAIDS – do not increase risk of spinal hematoma
- Ticlid = 14 day, Plavix = 7 days, Rheopro = 48 hours, Integrilin 8 hours
91
Neuraxial Blockade and Anticoagulation
Standard Heparin:
- Minidose SQ not contraindicated
- If getting heparin intraop – block must be done 1 hour prior at least
- Check PTT
92
Neuraxial Blockade and Anticoagulation
LMWH (Lovenox):
- Concern with epidural removal (1 hour prior to med or 10 hours after )
- INR is <1.5
93
Neuraxial Blockade and fibrinolytics
Fibrinolytic/Thrombolytic Therapy
| Avoid neuraxial anesthesia
94
Neuraxial Blockade and herbals
Herbal Medication:
- Feverfew, garlic, ginkgo or ginseng, glucosamine and chondroitin
- No single evidence
- One report of subarachnoid hemorrhage patient taking ginkgo
95
Preoperative Evaluation:
```
Preoperative Evaluation:
-Obtain preoperative anesthetic assessment
Lab results
-Patient Education:
*Risks
*Benefits
*Alternatives
*Potential complications
-Informed consent
-Back-up plan
```
96
what blood work would you want to check with neuraxial?
platelets
97
Technical Considerations
- Need to have resuscitation and intubation equipment available
- Explain procedure to patient it minimize anxiety
- Consider premedication (not in OB)
- Supplemental O2 – avoid hypoxemia
- Monitoring is necessary
98
Cervical and Lumbar spinous processes are
horizontal.
- Slight cephalad angle
- C2 first palpable, C7 most prominent
- Tuffier’s line L4-5 interspace (highest points of both iliac crests)
- S2 - Posterior superior iliac spine
99
Thoracic spinous processes ...
slant in caudal direction
More cephalad angle
T7 at level inferior angle of scapula
100
Positioning
-Sitting
- Lateral Decubitus
* Pt on side with knees flexed and pulled high against abdomen and chest
* “Fetal position”
- Prone
* Good for anorectal procedures – hypobaric
* CSF does not flow freely, need to aspirate
101
Start advancing the needle Midline approach – LAYERS
- Skin
- Subcutaneous fat
- Supraspinous ligament
- Interspinous ligament
- Ligamentum flavum
- Dura mater
- Subdural space
- Arachnoid mater
- Subarachnoid space- CSF
102
If you hit bone:
- superficially you are hitting lower spinous process
- Deeper you are hitting the upper spinous process
- Lateral you are hitting the lamina
103
Paramedian approach: layers
- Skin
- Subcutaneous fat
- Paraspinous muscle
- Ligamentum flavum
- Dura mater
- Subdural space
- Arachnoid mater
- Subarachnoid space- CSF
104
Paramedian approach:
- Selected if patient has positioning difficulties or block is difficult
- Same prep and drape
- Skin wheal of LA 2 cm lateral to the inferior aspect of superior spinous process
- Directed and advanced at a 10-25 degree angle toward the midline
* Avoid most of ligaments
* LF and epidural space entrance less subtle
105
spinal
Nerve roots blocked by LA through SAS
106
spinal needle that is Cutting (sharp)
Quincke H/A
107
spinal needle that is Blunt (pencil point)
Whitacre
| Sprotte
108
Spinal Catheter
- No longer approved by the FDA
- Withdrawal of these catheters was prompted by their association with cauda equina syndrome
- Epidural catheters high complication rates
109
Smaller gauge needle
allows less CSF leak, difficult to insert, aspirate CSF, & inject medication (25-26 gauge)
-Most clinicians will use the 25-26 gauge needle placed through an introducer
110
Larger gauge needle
improves tactile feel, higher risk of PDPH (20-22 gauge)
111
Tetracaine
2ml ampule of 1% (10mg/ml)
| Provides a more profound motor block
112
Bupivicaine
- 2ml ampule of 0.75% (7.5mg/ml) with 8.25% dextrose- packaged hyperbaric
- Onset of 3-5 minutes
- Less motor block than tetracaine
- Blocks sensory nerves that modulate tourniquet pain better than tetracaine
113
Lidocaine
- 2ml ampule of 5% (50mg/ml) solution premixed with 7.5% dextrose- hyperbaric
- Risk of “Cauda equina syndrome” with this mixture
114
Procaine
- 2ml ampule of 10% (100mg/ml) solution
- Short duration, low potency
- Solutions of greater than 5% concentration are linked to neurotoxicity
115
```
bupivicaine:
conc
dose
duration
with epi
onset
```
- 0.75%
- 8-12 mg to T10
- 14-20 mg to T4
- 90-110 min
- 100-150 min
- 5-8 min
116
```
Lidocaine
conc
dose
duration
with epi
onset
```
- 5%
- 50-75 mg to T10
- 75-100 mg to T4
- 60-70 min
- 75-100 min
- 3-5 min
117
Intrathecal Opioids
- Will not produce surgical analgesia
| - Does provide better anesthesia when combined with LA
118
Fentanyl:
dose
onset
duration
- Dose- 15-25 mcg
- Higher doses produce respiratory depression, itching, and urinary retention
- Onset 5-10 minutes
- Duration 2-4 hours
119
Sufentanyl
Not commonly used
| Dose 2-4 mcg
120
Meperidine
Preservative free 5-50mg of 5% solution
121
Morphine (preservative-free)
- Most commonly used
- Onset of 60-90 minutes
- Dose 0.1-0.5mg (usually give about 0.3)
- Provide profound analgesia for 18-27 hours
- Peak in resp depression is about 8 hours
122
SAB documentation
SAB: In sitting position (L or R lateral position) L4 – L5 identified. Sterile prep (betadine) and drape. Xylocaine 1% skin wheal at L4. Introducer placed. #27° Whitacre spinal needle placed x 1. (+) CSF (-) heme (-) paresthesia. Meds: bupivacaine 10.5 mg, fentanyl 15 mcg, Total volume: 2 ml. Position: supine/LUD. Level: T6. Procedure tolerated well. SAB tray #.......
123
Hyperbaric =
denser (heavier) than CSF
- Glucose additive
- Spreads cephalad, unless head up then spreads caudad
124
Hypobaric =
less dense (lighter) than CSF
- Water additive
- Spreads caudad, unless head up then spreads cephalad
125
Isobaric =
remain at level of injection site
| -Would add csf
126
Baracity
- It is the density of the LA at a specific temperature divided by the density of the CSF at the same temperature
- Density of CSF 1.004-1.008
- This determines where the LA will distribute
127
Hyperbaric
- Solution that has a density greater than the CSF (>1.008)
- Dextrose is used to make solution hyperbaric
- Most commonly used
- Allows us to inject at the lumbar area then place pt in slight trendelenburg position and allow the LA to move cephalad to bathe the upper lumbar and thoracic nerve roots
- Sitting the pt after injection of LA for 3-5 minutes after injection confines the LA to the lower lumbar and sacral roots (saddle block)
128
Hypobaric
- Solution that has a density less than the CSF where injected (<1.008)
- It will float up to the least dependent area within the spinal cord
- Diluted with preservative free sterile water
- Very dilute solutions require a larger volume of LA to deliver an effective mass of drugs
- 5-10mL
129
Isobaric
- Limited clinical application
- They do not spread with position change and are ideal when repositioning is required
- Difficult to obtain a high level
130
rule of thumb for dosing
- For a T4 level: Give 1 cc for 1st 5 feet and .1cc for every 2 inches.
- For T10= 70%
- For S2/S5= 40%
131
Other Factors Affecting Level of Blockade
- Position of patient during & after injection
- Dosage of drug
- Level of injection
- Patient’s height
- Vertebral column anatomy
- Direction of needle bevel
- CSF volume
* Decreased = higher blocks (pregnant, elderly, tumors)
132
Spinal Anesthetic Agents
- Preservative free LA ONLY
- Procaine, bupi, tetra,
- No lido, no Ropi
133
Vasopressors –
- limit uptake - PROLONG
- Epinephrine – 0.1-0.2mg (epi wash; aspirate epi and the empty syringe)
- Phenylephrine – 1-2 mcg
134
Spinal tetracaine better motor blockade in comparison to bupivacaine
Bupi with epi modestly increases duration, phenylephrine no effect
Tetra with epi prolongs more than 50%, phenylephrine prolongs
Spinal tetracaine better motor blockade in comparison to bupivacaine
Bupi with epi modestly increases duration, phenylephrine no effect
Tetra with epi prolongs more than 50%, phenylephrine prolongs
135
Lidocaine in spinal causes
CES and TNS
136
how long to sit for saddle block?
3-5 mins
137
Cauda Equina Syndrome
-Nerve damage to the cauda equina.
-There is a specific pattern:
-Severe pain in radicular (nerve root) pattern: back, buttocks, perineum(saddle area), genitalia, thighs, legs.
-Loss of sensation: often tingling or numbness in the saddle area.
-Weakness: in legs, often asymmetric
Bladder/bowel/sexual dysfunction: incontinence / retention of urine; incontinence of feces; impotence/loss of ejaculation or orgasm
-Loss of reflexes: knee/ankle reflexes may be diminished, as may anal and bulbocavernosus. (a muscle of the perineum, the area between the anus and the genitals)
138
TNS
- Transient neurotoxicity of concentrated local anesthetics has been thought to be the main reason for transient neurological symptoms
- Profound musculoligamental relaxation by high doses of local anesthetics may contribute to the development of postoperative musculoskeletal pain
- Loss of strength of the supportive structures of the spine
139
Three ligament structures act as landmarks that help identify and access to the epidural & subarachnoid space
Supraspinous ligament
Interspinous ligament
Ligamentum Flavum
140
epidural space
- Is a potential space outside the dural sac
- Continuous from the base of cranium to the base of the sacrum
- Contains epidural veins, fat lymphatics, segmental arteries and nerve roots
141
EPIDURAL ANESTHESIA
- Wider range of application than spinal anesthetic
- LAs or other analgesic solutions injected into the epidural space spread anatomically
- Can be performed at the lumbar, thoracic, or cervical levels
142
Epidural use
- Epidurals are used for operative anesthesia, obstetric analgesia, postoperative pain control, and chronic pain management
- May be used as a single injection technique or with a catheter
143
epidural variables
- Motor block can range from none to complete
- Variables controlled by the choice of medication, concentration, dosage, and level of injection
- Slower in onset (10-20 minutes) and usually not as dense as spinal anesthesia
- May be manifested as a more pronounced differential block or a segmental block
144
Lumbar epidural
- Most common anatomic insertion site
- Midline or paramedian approach may be used
- Lumbar epidural anesthesia may be used for any procedure below the diaphragm
- Extra measure of safety in performing the block in the lower lumbar interspaces
145
Thoracic Epidural
- Technically more difficult to accomplish with an increased risk of spinal cord injury
- Midline or paramedian approach may be used
- Rarely used as a primary anesthetic
- Most commonly used for intraoperative and postoperative analgesia
- Single injection or catheter techniques may be used
146
Cervical blocks
- Usually performed with the patient sitting, neck flexed, and using the midline approach
- Used primarily for pain management
147
Abnormal curvature
- Scoliosis-**Most common
- Kyphosis
- Lordosis
148
Epidural space surrounds the
dura mater posteriorly, laterally, and anteriorly
149
Nerve roots travel in the epidural space as they exit
laterally through the foramen
150
Is a potential space and is continuous from the base of the cranium to the base of the sacral sulcus
epidural space
151
epidural space contains
Contains epidural veins, fat, lymphatics, segmental arteries, and nerve roots
152
Epidural needle
- Standard epidural needle is typically 17-18°, 3 or 3.5” long, and has a blunt bevel with a gentle curve of 15-30° at the tip
- Tuohy needle most commonly used
153
purpose of the blunt tip
The blunt, curved tip helps push away the dura after passing through the ligamentum flavum
-Needle modifications include winged tips and introducer devices set into the hub
154
Placing a catheter into the epidural space allows for
continuous infusion or intermittent bolus techniques
155
Typically, a 19-20° catheter is introduced through a 17-18° epidural needle
Typically, a 19-20° catheter is introduced through a 17-18° epidural needle
156
Catheter threaded through the needle and into the epidural space to a depth of
3 to 5 cm into the space
Never attempt to withdraw catheter through needle!!
157
Test Dosing
- 3 mL of rapid acting low toxicity local anesthetic with epi
- Lidocaine 1.5 % with 1: 200,000 epi
- 45 mg Lidocaine with 15 mcq of epi in 3 mL
158
what happens if test dose is in wrong space
- If tip of needle is in subarachnoid space the dose will result in spinal in 3 min
- If injected intravascular 15 mcq of epinephrine will result in 20% rise in HR and systolic Blood pressure
- Always reassess after test dose
159
Symptoms of Intravascular injection
- Tinnitus
- Metallic taste
- Circumorally numbness
- Rushing sound in ear
160
epidural approach
Advance the epidural needle through the supraspinous ligament and seat it in the interspinous ligament. The needle should not droop when it is released
161
Epidural anesthesia requires that the needle stop short of piercing the
dura
162
Two techniques used to determine needle has entered the epidural space:
Loss of resistance technique
- Loss of resistance technique
163
Loss of resistance technique
Once needle is placed in the interspinous ligament, stylet removed and a glass syringe filled with ~2 ml, of fluid or air is attached to the hub. Needle slowly advanced with either continuous repeating attempt at injection. As the needle tip enters the epidural space there is a sudden loss of resistance and injection is easy
164
Rule of thumb for epidurals
1.0-2.0 ml of LA per segment of block desired. Administer 3-5 ml of LA every 3 minutes until desired level is achieved
165
How to avoid systemic toxicity and intrathecal injections
If initial test dose used, catheter aspirated prior to each injection, and incremental dosing used, significant systemic toxicity and inadvertent intrathecal injections are rare!
166
-Usual Test dose
| Average Distance from skin to epidural Space-
Usual Test dose Lido 1.5% with Epi 1:200k= 3cc
| ***Average Distance from skin to epidural Space- Avg. adult 4-6cm
167
obese
Obese up to 8cm thin person 3cm. Catheter epidural space 3-5cm
168
*** Adults 1-2ml per segment to be blocked. With age and height decrease dosage 1ml per segment i.e.-Achieve T4 sensory block from L4-5 (12-24ml)
*** Adults 1-2ml per segment to be blocked. With age and height decrease dosage 1ml per segment i.e.-Achieve T4 sensory block from L4-5 (12-24ml)
169
S2-S5
| for what type of surgery
hemorrhoids
170
L2-3 Surgery
knee, foot surgery
171
L1
Lower Extremity
172
T10
TURP, hip sx
173
T6-7
Appendectomy
174
T4
c section
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epidural documentation
Epidural placement: In sitting position (L or R lateral position) L4 – L5 identified. Sterile prep (betadine) and drape. Xylocaine 1% skin wheal at L4. #17° touhy needle to epidural space with LOR x 1. Epidural catheter placed 10 cm at skin (-) CSF, (-) heme, (-) paresthesia. Test dose Lidocaine 1% w/epi (1:200) x 3ml, no changes in HR (70’s-80’s). Epidural catheter secured and dosed with... Position: supine. Level T6. Procedure tolerated well. Epidural tray #...
Signature:
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epidural may Not be as predictable as with spinal anesthesia
yup
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Dose requirements of epidural anesthesia
decreases with age
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patient height and epidural
- Patient height affects the extent of cephalad spread
- Shorter patients may require only 1 ml of LA per segment to be blocked
- Taller patients generally require 2 ml per segment
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Spread of epidural LAs tends to be partially affected by
gravity
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Additives to epidural
- Opioids tend to have a greater effect on quality of block
- Epinephrine prolongs the effect
- Sodium bicarbonate may accelerate the onset of blockade
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Short-intermediate acting agents:
1.5-2% lidocaine
3% chloroprocaine
2% mepivacaine
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Long acting agents:
0. 25-0.5% bupivacaine
| 0. 5-1% ropivacaine
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Fast to Slow Onset-
| duration shortest to longest
```
Chloroprocaine
Lidocaine
Mepivacaine
Prilocaine
Bupivacaine
Ropivacaine
```
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TECHNICAL DIFFICULTIES
-Broken needles:
Most common cause is “burying” the needle
-Broken or sheared catheters:
Never pull a catheter back through the insertion needle
Always chart that tip of catheter intact when removed
Visually inspect catheter prior to insertion
-Glass from vials in the epidural space:
Break away from the tray and use a 4 x 4
Use filter needles
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complications cardiovascular
- Blockade of sympathetic fibers
- Blockade of cardioaccelator fibers
- Causes hypotension and bradycardia
- BP is decreased by 15-20% in most healthy pt’s
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How to treat hypotension
- Try to prevent it
* Preload
* Prophylactic administration of 1-2L of crystalloid
- Supplementary O2
- In pt’s with essential HTN
* Treat drops in BP aggressively
- Treatment
* Slight head down position- Trendelenburg
* Bolus of crystalloid
* Ephedrine 5-10mg IV
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epidural complications -Intercostal muscle paralysis
* Loss of sensory awareness of chest and abdominal motion
* May cause anxiety in the pt
* Give the pt O2 and reassure them
* Diminished ability to cough
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epidural complications apnea
- Apnea/ Phrenic nerve paralysis
* Immediate intervention
* Secure the airway
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epidural complications neurologic injuries
- Paresthesias or paraplegia
- Do a thorough pre-op interview and document any deficits
- If symptoms occur get an immediate neuro consult
- Most resolve within 1-6 months
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epidural complications Traumatic puncture/Paresthesia
- If paresthesia is encountered during needle placement- STOP
- If paresthesia continues after needle removal, abandon procedure
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epidural complications Subarachnoid or Epidural Hematoma
- Appearance of symptoms and neurologic impairment makes this a neurological emergency
- If block last longer then expected a hematoma should be ruled out
- Reappearance of blockade should warrant investigation
- Severe post-op back pain or spasm warrants investigation
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epidural complications Anterior Spinal Artery Syndrome
-Caused by a compromise in blood supply
-Signs and symptoms are sudden
Flaccid paralysis
-Appearance of symptoms and neurologic impairment makes this a neurological emergency
-If block last longer then expected a hematoma should be ruled out
-Reappearance of blockade should warrant investigation
-Severe post-op back pain or spasm warrants investigation
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epidural complications: epidural abscess
- Use sterile technique
- Symptoms occur within 1-3 days
* Severe back pain and tenderness, fever, and paralysis
* Elevated WBC
- Urgent surgical evacuation of abscess
- Antibiotics
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Cauda Equina Syndrome
- Numbness, tingling, and motor weakness of the lower extremities
- Caused by a hyperbaric concentration of LA confined to a small area
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epidural complications backpain
-related to duration of blockade
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epidural complications urinary retention
Autonomic blockade of bladder muscle and sphincter
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epidural complications inadequate block
- If a block fails you must have plan B available
- Local infiltration at site
- General anesthesia
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epidural complications subdural block
- Inject LA between the dura & arachnoid mater
- Onset similar to high spinal but slower
- Support circulatory and respiratory function
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epidural complication spinal headache PDPH
- Cephalgia that is occipital and radiates to the frontal or orbital regions
- Cervical muscle spasms
- Symptoms are postural
* Get worse when the pt’s head is elevated
- Nausea, vomiting, photophobia, tinnitus, dizziness, and cranial nerve palsies
- Caused by dural puncture and continuous leak of CSF
* Reduces CSF pressure
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treatment of PDPH
- Will resolve within 5-7 days
- Conservative therapy for 24 hours
* Bed rest, hydration, analgesics, and IV caffeine
- Epidural blood patch
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Epidural blood patch
-Epidural blood patch
Autologous blood is injected into the epidural space
-Blood will move in the cephalad direction so inject one interspace below
-The injected blood will increase subarachnoid and epidural pressure and form a clot sealing the dural tear
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Blockade of the posterior nerve root fibers interrupts somatic and visceral sensation. Blockade of anterior nerve root fibers prevents efferent motor and autonomic outflow.
Blockade of the posterior nerve root fibers interrupts somatic and visceral sensation. Blockade of anterior nerve root fibers prevents efferent motor and autonomic outflow.
