Spinal Surgery Anesthesia Flashcards
1
Q
What types of anestheisa should be avoided when MEPs/SSEPs are being monitored?
A
- no paralytics!
- no regional/neuraxial anesthesia
2
Q
What is scoliosis?
A
Lateral rotation of the spine > 10° with vertebral rotation.
Congenital or Idiopathic
3
Q
Adult onset scolisosis sxms:
A
- arthritis & disc degeneration
- spinal stenosis
- misalignment of vertebrae & nerve compression
- Radiculopathy: pinching of nerve root @ spinal column
- Sciatica
4
Q
What are the respiratory effects of thoracic spine scoliosis?
A
- ↓ Chest wall compliance
- Restrictive lung disease
- ↓ exercise tolerance
- chronic hypoxemia (V/Q mismatch)
- increased PVR (cor pulmonale)
Get PFTs!
5
Q
PFTs in thoracic scoliosis
What happens w/ FEV1/FVC in thoracic scoliosis?
A
forced expiratory vol in 1 sec/forced vital capacity
Normal/Increased in Thoracic Scoliosis
Normal: 0.8 (80%)
6
Q
PFTs in thoracic scoliosis
What happens with Peak Expiratory Flow Rate in thoracic scoliosis?
A
- decreases b/c the lungs are less full (more elastic recoil & harder to get air in)
7
Q
What happens to TLC, RV, and FRC in thoracic scoliosis?
A
- all decrease (restrictive lung dz)
8
Q
What EKG/cardiac findings might one suspect to find on a scoliosis patient? (Select all that apply)
a. RVH
b. RAE
c. LVH
d. Bi-atrial enlargement
A
a & b
9
Q
The increased pulmonary vascular resistance of chronic, significant scoliosis can lead to ___ _______.
A
cor pulmonale
Enlarged RV due to lung disease.
10
Q
What 7 things can lead to large blood loss in corrective surgery?
A
- surgical technique
- operative time
- # of levels fused
- MAP
- plt abnormalities
- dilutional coagulopathy
- primary fibrinolysis
11
Q
What muscles would you expect to be effected from a C5 injury?
A
- Partial diaphragmatic paralaysis
- Deltoids
- Biceps
- Brachialis
- Brachio-radialis
12
Q
What are the hemodynamic consequences of injuries T5 and higher?
A
Physiologic Sympathectomy
- ↓BP
- ↓HR
Tx: Midodrine (alpha 1 agonist)
13
Q
What is the pathophysiologic response of injuries higher than T1-T4?
A
bradycardia
Tx: epinpehrine
Atropine/glycopyrrolate will not work
14
Q
Autonomic Hyperreflexia is most often seen with cord transection above the ____ level.
A
T5/T6
15
Q
What s/s are seen with autonomic hyperreflexia?
A
- Severe, transient HTN
- Bradycardia
- Dysrhythmias
- Cutaneous dilation above the injury
16
Q
In autonomic hyperreflexia, cutaneous vasodilation is seen _____ the site of injury, whilst cutaneous vasoconstriction is seen ____ the site of injury.
A
above ; below
17
Q
What is the basic pathophysiology of Autonomic Dysreflexia?
A
- stimulus
- afferent signal to cord
- massive sympathetic response
- widespread vasoconstriction
- HTN
- sensed by baroreceptors - signal brain (IX, X)
- HR slowed (X)
- Descending inhibitory signals blocked @ SCI level
18
Q
What are the most common causes of Autonomic Dysreflexia?
A
- Distended bladder/bowel
- Noxious stimuli (think surgical pain)
19
Q
What is the treatment for Autonomic Dysreflexia?
A
- Removal of stimulus
- Deepen anesthetic
- Direct-acting Vasodilators
20
Q
What direct acting vasodilators can be used for autonomic dysreflexia?
A
- Hydralazine 5-10mg
- Minoxidil: opens K+ ATP channels = hyperpolarization & vasodilation
- Sodium Nitroprusside 0.3 - 10 mcg/kg/min
21
Q
Injury to C3-C5 results in….
A
Diaphragmatic respiratory failure
22
Q
Is respiratory function affected by injury to C5-C7?
A
Yes; impairment of abdominal and intercostal respiratory support
restricts chest excursion = atelectasis
23
Q
Why is there an increased risk of pulmonary infection with cervical spine injuries?
A
- Inability to cough/ clear secretions
- Atelectasis
24
Q
What is poikilothermia?
A
Inability to maintain constant core temp
25
What is the pathophysiology of poikilothermia?
- SNS disruption
- Temperature sensation disruption
- Inability to vasoconstrict below spinal cord injury
26
Spinal deformities are associated with _______ respiratory patterns, often necessitating PFT's and an ABG.
Restrictive
* decreased FEV1, FVC, TLC, RV, FRC
* normal/increased FEV1/FVC ratio
27
Spinal deformities can lead to CV compromise such as ____________. This leads to ________ ________, poor filling, ____, and A-fib.
* compression of the heart
* diastolic dysfunction
* HF
28
Flaccidity in which two muscles would indicated possible cervical spine fracture?
- Deltoids
- Biceps
29
What 3 things should we avoid injury to in spinal surgeries?
* eyes
* peripheral nerves
* bony prominences
30
What is the anterior cervical spine positioning?
* arms tucked neutral
* head on headrest (donut)
31
What is the posterior cervical spine positioning?
* arms tucked neutral
* head in mayfield device (stimulating - give 50-100mg propofol)
32
What is the greatest risk with a total sitting position?
VAE (Venous Air Embolism)
33
An anterior approach for a thoracic spine procedure requires what position and equipment?
- Lateral position with bag
- **Double Lumen ETT** or bronchial blocker
*May have to drop lung for access*.
34
A posterior approach for a thoracic spine procedure requires what position and equipment?
- Prone with arms tucked or 90° abduction
- gel head rest or prone view
- **Single lumen ETT**.
35
When doing prone positioning, what are the airway concerns/interventions?
1. add corrugated adapter
2. risk of ett kinking
3. assess for BBS after flipping
4. unintentional extubation
5. airway edema
36
What are the three causes of postoperative vision loss secondary to prone positioning?
- Ischemic Optic Neuropathy (ION)
- Retinal vessel occlusion
- Cortical brain ischemia (stroke, CVA)
## Footnote
**intentional HoTN or General HoTN**
37
T/F. Ischemic optic neuropathy occurrence requires direct pressure placed on the eyes?
False. Can occur without direct pressure.
*Occurs due to ↓ blood flow or O₂ delivery.
38
What are risk factors for ION?
- Male
- Obesity
- Wilson Frame Use
- > 6 hour surgery
- ↓ colloid usage
- Blood loss > 1000 mL
39
What is the typical onset of ION?
24 - 48 hours
40
What are the symptoms of ION?
Bilateral
- Painless vision loss
- Non-reactive pupils
- No light perception
41
What are the treatments for ION?
And what is the goal of the treatment?
- Acetazolamide (Diamox)
- Diuretics (Lasix, Bumex)
- Corticosteroids (Decadron)
- Hyperbaric O₂
**Goal: ↓ IOP, ↑ blood flow to optic n., ↓ ischemia**
42
What causes central retinal artery occlusion?
↓ blood supply to entire retina
43
What does occlusion to a branch of the retinal artery cause?
↓ blood supply to a part of the retina
44
What time of frame pictured below?
Wilson Frame
* partial abdominal compression
* pelvis partially supported
* legs slightly below heart
45
What table is this?
Jackson Spine Table
* more abdominal excursion - does not restrict ventilation
* Pelvis supported
* legs @ heart level
46
What are the respiratory effects of prone positioning?
↓ FRC
↓ compliance
*Due to ↑ intrabdominal pressures → ↑ intrathoracic pressures*.
47
Does venous return increase or decrease in prone positioning?
decrease
48
Which of the following positioning devices is the most stable?
Mayfield Tongs
49
What cardiac consequences are there to prone positioning?
Why?
- ↓ preload
- ↓ CO
- ↓ BP
*Due to pooling of blood in extremities and compression of abdominal contents and muscles*.
50
What neurological consequences occur due to prone positioning?
↓ cerebral venous drainage and ↓ CBF
51
What risk factors are there for increased blood loss during spinal surgery?
- Number of vertebrae
- > 50 yo
- Obesity
- Tumor surgery
- ↑ intrabdominal pressure
- Transpedicular osteotomy: cutting/shaping of bone
52
When is autologous blood donation contraindicated in spinal surgery?
- Significant cardiac disease
- Infection
*involves donating blood 1-2 weeks prior to surgery*
53
What is the push dose of TXA?
- 10 mg/kg IV
54
What is the infusion dose of TXA?
2 mg/kg/hr
55
What is the max dose of TXA?
2.5g
56
What is the push dose of aminocaproic acid?
Infusion dose?
Push dose: 100 mg/kg IV
Infusion: 10 - 15 mg/kg/hr
57
Somatosensory Evoked Potentials (SSEPs) are associated with what spinal column and sensations?
Dorsal column pathways
- Proprioception
- Vibration
Afferent pathway from periphery to CNS
## Footnote
**sensory in the back**
58
Motor Evoked Potentials (MEPs) are associated with what spinal column and sensations?
Anterior/ Motor Column
* Efferent pathway from CNS to periphery
## Footnote
**motor in the back**
59
During spinal surgery, electromyogram (EMG) is used to monitor for what during pedicle screw placement and nerve decompression?
Monitor for **nerve root injury**.
60
What is an SSEP?
Impulse from a peripheral nerve that is measured centrally.
61
What are Motor Evoked Potentials (MEPs)?
Impulse triggered in the brain (centrally) and monitored in specific muscle groups.
62
What are possible adverse effects associated with MEPs? (6)
- Cognitive defects
- Seizures
- Intraoperative awareness
- Scalp burns
- Cardiac arrythmias
- Bite injuries (bite block necessary)
63
In what patients should MEPs be avoided?
- Patients w/ active seizures
- Patients w/ vascular clips in brain
- Patients w/ cochlear implants
64
Differentiate amplitude and latency in regards to neurophysiologic monitoring.
Amplitude: signal strength
Latency: time for signal to travel through spinal cord.
65
What physiologic factors commonly can affect amplitude and latency of neurophysiologic monitoring?
- Hypothermia
- Hypotension
- Hypocarbia
- Anemia
- **VAAs**
66
How do VAAs affect neuromuscular monitoring?
Dose dependent
- ↓ amplitude
- ↑ latency
67
Out of the following drugs, which affects our MEPs the most?
- Opioids
- Midazolam
- Ketamine
- Propofol
Propofol **depresses MEPs**.
*The others have little effect on MEPs*.
68
How does Nitrous affect MEPs?
* ↓ amplitude - do not use
69
How much does muscle relaxant requirement increase when using MEPs?
Trick question. **No muscle relaxants after intubation.**
70
What should be done if there is an acute change in amplitude/latency during surgery?
* d/c surgery
* BP - normal to 20% of baseline
* ↓ or d/c VAs
71
What 4 factors may require post-op ventilation in spinal surgeries?
* procedure length > 4 hrs
* thoracic cavity invasion
* EBL > 30mL/kg or > 2000mL (oxygenation support)
* Facial/laryngeal edema (leak test)
72
What type of nerve block might be used for spinal surgery?
Erector Spinae block
73
During what surgery is venous air embolism at its greatest risk of happening?
Laminectomies
- Large amount of exposed bone
- Surgical site above the heart
74
What are some s/s of VAE?
- Unexplained ↓BP
- ↑ EtN₂
- ↓ EtCO₂
75
Double Lumen Tube Sizes:
Adult:
Pedi:
Adult: 35, 37, 39, 41 Fr
Pedi: 26, 28, 32 Fr
76
When would we use a R DLT?
* L pneumonectomy
* L Lung transplant
* L mainstem bronchus stent in place
* L tracheo-bronchus disruption
77
How is a DLT placed?
1. advance through larynx w/ angled tip anterior into trachea
2. bronchial cuff passes cords
3. turn tube 90 degrees toward appropriate bronchus
4. verify placement of bronchial port w/ fiberoptic scope
5. inflate bronchial balloon under direct visualization
6. ensure bronchial cuff does not herniate over carina
7. isolate lung by clamping either tracheal or bronchial connector
78
Where should the bronchial port of a DLT sit?
* just below the carina in the appropriate bronchus
79
What are possible DLT complications?
* tube malposition
* hypoxemia (PEEP to dependent lung, intermittent 2 lung ventilation, passive oxygenation)
80
Indications for Bronchial-Blockers
* nasal intubation
* difficult intubation
* pts w/ trach
* subglottic stenosis
* continued post-op intubation
* if single lumen tube already in place
81
Difficulties w/ bronch blockers:
* RUL takeoff high
* tracheal bronchus
