Epidural Anesthesia Flashcards
1
Q
what is an epidural anesthetic?
A
- reversible chemical blockade of neuronal transmission produced by the injection of a local anesthetic into the epidural space to the region of the dural cuffs
- leaks into intravertebral foramen and prarvertebral spaces
- medication spread is diffusion dependent
- onset longer
2
Q
what does an epidural anesthetic block?
A
-temporary interruption of autonomic, sensory and motor nerve fiber transmission that is dependent on the drug concentration and volume of drug instilled into the space
3
Q
advantages of epidural anesthesia
A
- reduces surgical stress
- reduces overall blood loss (debated in literature)
- decreases risk of DVT (MOA unknown, but maybe stops stress response and interrupts coagulation cascade)
- provides anesthesia and/or analgesia –> can re dose with catheter or convert from pain management to primary anesthetic
- it is versatile –> you can control the extent of the sensory and motor blockade; can be used with adjuncts
4
Q
disadvantages of epidural anesthesia
A
- PDPH due to larger needle
- sympathetic blockade occurs 100% of the time (hypotension, bradycardia)
- block may last much longer than the procedure
- urinary retention
- regional takes “too much time”
- more difficult than spinal
5
Q
why would you pick an epidural?
A
- discuss case with the surgeon, could be part of a multimodal pain management in ERAS
- management of labor pain
- procedures involving the abdomen or lower extremities
- certain comorbidities - pulmonary disease
6
Q
absolute contraindications to epidural
A
- patient refusal
- increased ICP (can cause brainstem herniation)
- severe aortic or mitral valve stenosis
- coagulopathy or bleeding diathesis
- severe hypovolemia
- infection at the injection site
7
Q
relative contraindications to epidural
A
- uncooperative patient (unable to sit still = dangerous)
- local anesthetic allergy (esters PABA)
- patient on anticoagulant or thrombolytic therapy (patients with comorbidities like atrial fib or DVT)
- preexisting neurologic defect
- chronic HA or backache
- severe spinal deformity
- valvular stenosis
8
Q
patient assessment for epidural anesthesia
A
- preop does the patient understand the surgical technique
- explain spinal anesthetic and rational for preference
- address any patient concerns - fear of being awake or loss of control
- reassure patient
- NEVER force or coerce patient into any procedures
- age considerations
9
Q
what is involved in informed consent
A
- advantages and disadvantages
- block appropriate for procedure but not guaranteed
- risks and benefits
- ensure patient understands
- allow patient to ask questions
- do not attempt to dissuade from a general if already agreed to
10
Q
pre-procedure monitoring
A
- PIV large bore
- have suction
- have airway supplies
- ECG, BP, Pulse ox, oxygen if needed
- supportive meds - induction agent, paralytic, atropine, vasoactive meds
- support person ready to stand with the patient the WHOLE time
11
Q
positions used for epidural
A
- sitting
- lateral decubitus
- prone
12
Q
neelde approaches for epidural
A
- midline
- paramedian
13
Q
placement of epidural
A
- thoracic - spinous processes form a shield, need steep cephalad angle or paramedian approach
- lumbar - short, small spinous processes, midline OK
- caudal - in sacral hiatus; lateral or prone, needle almost parallel to spinal column
14
Q
patient positioning
A
- have assistant stand in front of the patient; assistant does NOT leave patients side
- have patient hold pillow or blanket or lean over a table; drop their head down; roll their back
- angry cat or shrimp position
- flexion of the spine will create larger intraspinous spaces and make your procedure more successful
15
Q
lateral approach patient psition
A
- maintain midline positioning
- limit spine rotation
16
Q
what things do you need prior to the start of the procedure?
A
- patient IV
- monitoring devices
- oxygen attached and functioning
- resuscitation equipment available
- walk patient through procedure
17
Q
prepping patient epidural procedure
A
- ensure proper positioning
- ensure comfortable for you too
- palpate landmarks with ungloved hand - iliac crests, spinous processes of lumbar vertebrae
- use most identifiable interspace (usually L2-3)
- examine one level above and one level below and if you can’t feel use ultrasound
- STERILE
- open tray and inspect integrity of components
- 3cc - local skin wheal
- 5cc - local injection
18
Q
what must you wear for the procedure?
A
- hat
- mask
- sterile gloves
19
Q
3 cc syringe
A
local skin wheal
20
Q
5 cc syringe
A
local injection
21
Q
steps of epidural procedure
A
- position patient
- find spot
- open tray using sterile technique
- prep patient with CHG or betadine - allow to dry
- set up tray and draw up medications (be consistent)
- cleanse site
- apply sterile drape with your site at the center of the circle
- straddle selected interspace with middle and index fingers of non-dominant hand
- raise a small intradermal skin wheal of LA with 25-27G needle (can advance as a guide to feel where you want to go)
- epidural needle placed with bevel cephalad
- advanced through - supraspinous, interspinous; advanced mm by mm; SLOW
- once through ligamentum flavum will feel loss of resistance
22
Q
epidural needles
A
- marked in 1 cm increments
- large needles
23
Q
standard epidural needle size
A
9 cm
24
Q
touhy needle
A
- pronounced curve
- easier for novices
- directional placement of catheter
- want bevel up and curve facing caudad so the catheter threads up
25
Q
crawford needle
A
- not curve
- easier to insert
- BUT higher rate of dural punctures
26
Q
standard depth to ligamentum flavum at lumbar level
A
5 cm
varies with level and body habitus
27
Q
bromage grip
A
- hand firm support to stabilize the needle
- attach and secure the syringe
- passing catheter through needles
- non-dominant hand stabilizes patient’s back
28
Q
alternate grip
A
- attach and secure syringe
- needle placed with bevel cephalad
- hands to stabilize needle on both sides
29
Q
loss of resistance method
A
- most common method
- glass or plastic syringe
- fill with 2-3 mL saline with air bubble
- attach to epidural needle
- resistance noted while needle is in the various ligaments until epidural space is entered
- pressure on back of needle; when feel loss of resistance, in the epidural space
30
Q
hanging drop method
A
- hub of epidural needle filled with saline until small drop visible
- negative pressure created as needle passes into epidural spaces SUCKS drop in
- more pronounced at thoracic levels
31
Q
dilation of epidural space
A
- once needle passes through the epidural space, immediate loss of resistance is noted
- contents of syringe injected into space
- when syringe is removed, common to see a small amount of clear fluid
- puncture of dura will result in LARGE amt of CSF
32
Q
epidural catheters
A
- typically 2 gauges smaller than needle
- open-ended
- multiport - lower incidence of inadequate analgesia; higher incidence of accidental vein cannulation
- markings help to identify depth of catheter placement
33
Q
dashed lines
A
1 cm
34
Q
two dashed lines
A
10 cm
35
Q
thick line
A
12 cm
36
Q
catheter placement
A
- when thick black mark is flush with hub, catheter is flush with needle tip
- slight resistance noted when catheter is advanced
- if catheter has a stylet, retract prior to advancing
- inform patient of possible paresthesia (if one occurs STOP)
37
Q
how far do you advance the epidural catheter?
A
3-5 cm past the needle hub
38
Q
shallow placement
A
can get dislodged from epidural space
39
Q
deep placement
A
- puncture of dura
- passage into epidural vein
- migration through intervertebral foramen
40
Q
remove needle
A
- slowly withdraw needle over catheter
- once needle is removed, note the depth of the catheter at the skin
- if depth is less than 1 cm to the epidural space REPLACE
- never attempt to withdraw the catheter through the needle
41
Q
test dose
A
- 1.5% lidocaine with epinephrine 1:200,000
- 15 mg/mL lidocaine and 5 mcg/mL epi
- inject 3 mL –> 45 mg lidocaine and 15 mcg epi
42
Q
subarachnoid placement
A
spinal - hypotension brady
43
Q
intravascular placement
A
greater than 20% increase in HR and BP
44
Q
secure catheter
A
- looped and taped away from midline
- minimizes chance of dislodgement
- keep OFF spinous processes
- placed over shoulder
- secure label to end of catheter!!
45
Q
paramedian approach
A
- useful when patient cannot flex spine (history of previous spine surgery, RA, or hip/upper leg trauma)
- skin wheal 1 cm lateral and 1 cm caudal to spinous process
- advance needle toward midline
- needle passes through paraspinous muscles to ligamentum
- does NOT pass through supraspinous or intraspinous ligaments
