spine surgery Flashcards
what are symptoms and timeline of alcohol withdraw in someone who presents for surgery?
tremors 6-8 hours
hallucinations 1-3days
> 3 days then life threatening delirium, confusion, agitation, autonomic instability (fever, tachy, HTN)
What anesthesia concerns do you have in someone with chronic alcohol abuse?
- increased MAC
- tolerance to drugs
- cognitive impairment
- cerebral atrophy
- cerebral degeneration
- peripheral neuropathy
- cirrhosis
- cardiomyopathy
What changes if someone stops smoking for 8 weeks before surgery
- reduced carboxyhemoglobin
- shifting oxyhemoglobin dissociation curve to the right
- improved ciliary function
- reduced nicotine levels
- airway hyperreactivity
- sputum production
- peri-operative pulm complications
What are SSEPs?
- somatosensory evoked potentials (SSEPs)
- monitor ascending sensory neural pathways in POSTERIOR spinal cord
- show decreased amp, increased latency with anesthetic suppression
- indirect monitor of anterior spinal cord function
Significant change means 50% drop in amplitude and/or 10% increased latency
what are MEPs
- motor evoked potentials (MEPs)
- detect motor injury
- detect descending motor pathways in the ANTERIOR spinal cord
- require TIVA
- MEPs more sensitive to gas (volatile agents) than SSEPs are
Significant change in MEP means 50% drop in amplitude
What is autonomic neuropathy?
- neuropathy of CNS
- S/S:
gastroparesis
GERD
orthostasis
painless MI
HTN
resting tachycardia
exercise intolerance
early satiety
peripheral neuropathy
dysrhythmias
N/V
RESISTANCE to INDIRECT acting agents like ephedrine
diabetic autonomic neuropathy often affects parasympathetic system first –> measure HR response to valsalva maneuver
What do you do if there’s a change in SSEP/MEP signals during spine case?
- correct hypoxia, hypotension, hypovolemia, anemia,
- check if too much anesthesia
- ask surgeon to r/o surgical causes like retraction
perform wakeup test
what is posterior ischemic optic neuropathy (PION)?
- most common cause of post-op vision loss
- decreased O2 delivery to optic nerve –> nerve damage
- presents within 1-2 days after surgery
- PAINLESS vision loss, decreased pupillary response to light in affected eye
- optic disc appears normal
- risks: long surgery > 6.5hrs, EBL 45% EBV
what is anterior ischemic optic neuropathy (AION)?
a/w cardiac surgery
painless vision loss
fundoscopic exam findings include optic disc edema in AION
how do you do a superficial cervical plexus block? Deep cervical plexus block?
superficial: inject 10cc of LA along posterior border of SCM
Deep: draw a line from mastoid process to Chassaignac’s tuberacle at the level of cricoid cartilage
C2 transverse process palpated caudad to the mastoid process, put 10cc of LA at C2 - C4 transverse process
what are complications of deep cervical plexus block
epidural/ subarachnoid injection phrenic nerve blocked inject into vertebral artery RLN blockade Horner's syndrome
what are options for neurologic monitoring during CEA?
- if regional, talking to patient
- stump pressure (pressures under 50 = hypo-perfusion)
- EEG
- SSEPs (measures response of sensory cortex to electrical impulses from peripheral sensory nerve stimulation)
- TCD of middle CA, detect embolic events
- cerebral ox
- jugular venous oxygen sat
- regional cerebral blood flow (IV carotid artery RA xenon injection)
what is myocardial preconditioning?
exposure to certain drugs protect the myocardium against MI and reperfusion injury
volatile agents do this even at a MAC of 0.25
involves opening K-ATP channels, prevent mitochondrial Ca2+ overload
during a CEA, HR drops to 48, BP drops to 88/40, what’s going on?
- surgical manipulation of carotid body and sinus (ask him to stop or infiltrate area with LA to prevent swings)
- myocardial depression
- MI or cardiac ischemia
- dysrhythmia
- pre-existing autonomic neuropathy
spinal cord injury to what level affects the diaphragm? What about chest wall innervation?
diaphragm C3-5
chest wall innervation C6- C7 –> can cause paradoxical breathing and inability to cough effectively or clear secretions –> atelectasis and infection