Spinal Surgery Anesthesia

Question 1

What is scoliosis?

Answer 1

Lateral rotation of the spine > 10° with vertebral rotation.

Question 2

What are the effects of thoracic spine scoliosis?

Answer 2

• ↓ Chest wall compliance
• Restrictive lung disease
• ↓ exercise tolerance

Get PFTs!

Question 3

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

Answer 3

a & b

Question 4

The increased pulmonary vascular resistance of chronic, significant scoliosis can lead to ___ _______.

Answer 4

cor pulmonale

Enlarged RV due to lung disease.

Question 5

What muscles would you expect to be effected from a C5 injury?

Answer 5

• Partial diaphragmatic paralaysis
• Deltoids
• Biceps
• Brachialis
• Brachio-radialis

Question 6

What are the hemodynamic consequences of injuries T5 and higher?

Answer 6

Physiologic Sympathectomy
- ↓BP
- ↓HR

Question 7

Autonomic Hyperreflexia is most often seen with cord transection above the ____ level.

Answer 7

T5/T6

Question 8

What s/s are seen with autonomic hyperreflexia?

Answer 8

• Severe, transient HTN
• Bradycardia
• Dysrhythmias
• Cutaneous dilation and constriction

Question 9

In autonomic hyperreflexia, cutaneous vasodilation is seen _____ the site of injury, whilst cutaneous vasoconstriction is seen ____ the site of injury.

Answer 9

above ; below

Question 10

What is the basic pathophysiology of Autonomic Dysreflexia?

Answer 10

Question 11

What are the most common causes of Autonomic Dysreflexia?

Answer 11

1. Distended bladder/bowel
2. Noxious stimuli (think surgical pain)

Question 12

What is the treatment for Autonomic Dysreflexia?

Answer 12

1. Removal of stimulus
2. Deepen anesthetic
3. Direct-acting Vasodilators

Question 13

Injury to C3-C5 results in….

Answer 13

Diaphragmatic respiratory failure

Question 14

Is respiratory function affected by injury to C5-C7?

Answer 14

Yes; impairment of abdominal and intercostal respiratory support

Question 15

Why is there an increased risk of pulmonary infection with cervical spine injuries?

Answer 15

• Inability to cough/ clear secretions
• Atelectasis

Question 16

What is poikilothermia?

Answer 16

Inability to maintain constant core temp

Question 17

What is the pathophysiology of poikilothermia?

Answer 17

• SNS disruption
• Temperature sensation disruption
• Inability to vasoconstrict below spinal cord injury

Question 18

Spinal deformities are associated with _______ respiratory patterns, often necessitating PFT’s and an ABG.

Answer 18

Restrictive

Question 19

Flaccidity in which two muscles would indicated possible cervical spine fracture?

Answer 19

• Deltoids
• Biceps

Question 20

What is the greatest risk with a total sitting position?

Answer 20

VAE (Venous Air Embolism)

Question 21

An anterior approach for a thoracic spine procedure requires what position and equipment?

Answer 21

• Lateral position with bag
• Double Lumen ETT or bronchial blocker

May have to drop lung for access.

Question 22

A posterior approach for a thoracic spine procedure requires what position and equipment?

Answer 22

• Prone with arms tucked or 90° abduction
• Single lumen ETT.

Question 23

What are the three causes of postoperative vision loss secondary to prone positioning?

Answer 23

• Ischemic Optic Neuropathy (ION)
• Retinal vessel occlusion
• Cortical brain ischemia

Question 24

T/F. Ischemic optic neuropathy occurrence requires direct pressure placed on the eyes?

Answer 24

False. Can occur without direct pressure.

*Occurs due to ↓ blood flow or O₂ delivery.

Question 25

What are risk factors for ION?

Answer 25

- Male - Obesity - Wilson Frame Use - > 6 hour surgery - ↓ colloid usage - Blood loss > 1000 mL

Question 26

What is the typical onset of ION?

Answer 26

24 - 48 hours

Question 27

What are the symptoms of ION?

Answer 27

Bilateral - Painless vision loss - Non-reactive pupils - No light perception

Question 28

What are the treatments for ION?

Answer 28

- Acetazolamide - Corticosteroids - Hyperbaric O₂

Question 29

What time of frame pictured below?

Answer 29

Wilson Frame

Question 30

What are the respiratory effects of prone positioning?

Answer 30

↓ FRC ↓ compliance *Due to ↑ intrabdominal pressures → ↑ intrathoracic pressures*.

Question 31

Does venous return increase or decrease in prone positioning?

Answer 31

decrease

Question 32

Which of the following positioning devices is the most stable?

Answer 32

Mayfield Tongs

Question 33

What cardiac consequences are there to prone positioning? Why?

Answer 33

- ↓ preload - ↓ CO - ↓ BP *Due to pooling of blood in extremities and compression of abdominal contents and muscles*.

Question 34

What neurological consequences occur due to prone positioning?

Answer 34

↓ cerebral venous drainage and ↓ CBF

Question 35

What risk factors are there for increased blood loss during spinal surgery?

Answer 35

- Number of vertebrae - > 50 yo - Obesity - Tumor surgery - ↑ intrabdominal pressure - Transpedicular osteotomy

Question 36

When is autologous blood donation contraindicated in spinal surgery?

Answer 36

- Significant cardiac disease - Infection

Question 37

What is the push dose of TXA?

Answer 37

- 10 mg/kg IV

Question 38

What is the infusion dose of TXA?

Answer 38

2 mg/kg/hr

Question 39

What is the push dose of aminocaproic acid? Infusion dose?

Answer 39

Push dose: 100 mg/kg IV Infusion: 10 - 15 mg/kg/hr

Question 40

Somatosensory Evoked Potentials (SSEPs) are associated with what spinal column and sensations?

Answer 40

Dorsal column pathways - Proprioception - Vibration

Question 41

Motor Evoked Potentials (MEPs) are associated with what spinal column and sensations?

Answer 41

Anterior/ Motor Column

Question 42

During spinal surgery, electromyogram (EMG) is used to monitor for what during pedicle screw placement and nerve decompression?

Answer 42

Monitor for **nerve root injury**.

Question 43

What is an SSEP?

Answer 43

Impulse from a peripheral nerve that is measured centrally.

Question 44

What are Motor Evoked Potentials (MEPs)?

Answer 44

Impulse triggered in the brain (centrally) and monitored in specific muscle groups.

Question 45

What are possible adverse effects associated with MEPs?

Answer 45

- Cognitive defects - Seizures - Intraoperative awareness - Scalp burns - Cardiac arrythmias - Bite injuries (bite block necessary)

Question 46

In what patients should MEPs be avoided?

Answer 46

- Patients w/ active seizures - Patients w/ vascular clips in brain - Patients w/ cochlear implants

Question 47

Differentiate amplitude and latency in regards to neurophysiologic monitoring.

Answer 47

Amplitude: signal strength Latency: time for signal to travel through spinal cord.

Question 48

What physiologic factors commonly can affect amplitude and latency of neurophysiologic monitoring?

Answer 48

- Hypothermia - Hypotension - Hypocarbia - Anemia - **VAAs**

Question 49

How do VAAs affect neurophysiologic agents?

Answer 49

Dose dependent - ↓ amplitude - ↑ latency

Question 50

Out of the following drugs, which affects our MEPs the most? - Opioids - Midazolam - Ketamine - Propofol

Answer 50

Propofol **depresses MEPs**. *The others have little effect on MEPs*.

Question 51

How much does muscle relaxant requirement increase when using MEPs?

Answer 51

Trick question. **No muscle relaxants after intubation.**

Question 52

What type of nerve block might be used for spinal surgery?

Answer 52

Erector Spinae block

Question 53

During what surgery is venous air embolism at its greatest risk of happening?

Answer 53

Laminectomies - Large amount of exposed bone - Surgical site above the heart

Question 54

What are some s/s of VAE?

Answer 54

- Unexplained ↓BP - ↑ EtN₂ - ↓ EtCO₂