Ortho - Spine Flashcards
Most spine surgeries require what type of anesthetic?
GETA
Long procedures (6-8 hrs) that are associated with decreased chest wall compliance + restrictive lung disease + risk of large blood loss
Scoliosis surgery
What findings might be present on EKG in a patient with scoliosis?
RVH: V1-V4 R wave progression
RAE: wide P wave in lead II
anticipate _______ with corrective scoliosis surgery
large blood loss
______ ________ can occur If patient has received > 2 L crystalloids intraop
dilutional coagulopathy (need to give albumin or blood products)
scoliosis surgery may require ________, but can have consequences if autoregulation/CPP not maintained.
intentional hypotension
Expect partial paralysis of diaphragm & cervical spine injury if these 4 muscles are noted to be flaccid?
deltoid
biceps
brachialis
brachio-radialis
** innervated by C5
Occurs with complete spinal cord transection above T5/T6
autonomic hyperreflexia
C3,4,5 keeps….
the DIAPHRAGM alive
SCI above the cardiac accelerator nerves leads to:
BRADYCARDIA
T1-T4
SCI at T5 & higher leads to:
sympathectomy = hypotension
** DOC = midodrine (A1 agonist)
What is the DOC for hypotension r/t SCI at or below T5?
midodrine (A1 agonist)
Severe transient HTN, bradycardia, dysrhythmia’s, severe HA, vision changes, N/V, & anxiety are symtpoms of:
autonomic hyperreflexia
Below the level of SCI, you would expect the patient to have cold, dry skin d/t:
autonomic hyperrelflexia (reflexive SNS response to pain)
cutaneous vasoconstriction & HTN BELOW level of injury
Above the level of the SCI, you would expect the patient to have hot, diaphoretic skin d/t:
autonomic hyperreflexia (lack of PNS compensation)
cutaneous vasodilation ABOVE injury
What are some causes of autonomic hyperreflexia in a patient with a SCI?
- distended/full bladder or bowels
- noxious stimuli (surgical)
How can we prevent autonomic hyperreflexia?
- deepen anesthetic
- remove stimuli (drain bladder)
If autonomic hyperreflexia does occur, how do we treat it?
deepen anesthetic + direct/fast acting vasodilators (nitroprusside, hydralazine, phentolamine)
SCI at C3-C5 can result in:
diaphragm paralysis –> respiratory failure
SCI at C5 - T7 can result in:
risk of infection from atelectasis & inability to cough d/t impairment of abdominal & intercostal support of respirations
inability to maintain constant core temperature
poikilothermic
inability to vasoconstrict BELOW level of SCI and disrupted temp sensations leads to:
poikilothermia
How can we help a SCI patient maintain constant core temp?
- warm IVF
- warm air/bare hugger
- increase OR temp if possible
airway management issues are more common in _____ & _____ spine cases
cervical & thoracic
severe kyphoscoliosis can result in:
CV compromise (pulm HTN~cor pulmonale)
flaccid deltoid & biceps can be a sign of:
cervical spine fracture
Recall the 6 P’s of a neurovascular assessment:
- pain
- poikilothermia
- paraesthesia
- paralysis
- pulselessness
- pallor
What type of X-ray may be required to better visualize atlanto-axial instability?
LATERAL x-ray
**esp in RA pts
When is regional or neuraxial anesthesia good for spine pts?
- lumbar laminectomy 1-2 levels (if no upper level involvement)
- disc surgery
How can we facilitate low venous pressure to surgical site (aka minimize blood loss) with positioning?
- maintaining a free abdomen
- reverse trendelenburg
Position for a cervical spine surgery with an ANTERIOR approach?
SUPINE
Position for a cervical spine surgery with an POSTERIOR approach?
PRONE
This position is uncommon in spine procedures and is associated with what risk?
sitting = VAE
Which THORACIC surgical approach requires a DLT or bronchial blocker to drop a lung?
ANTERIOR approach
A patient undergoing an anterior thoracic surgery will require what airway equipment?
DLT or bronchial blocker
Placement of a DLT to collapse the lung on the operative side may be required for surgery above ____
T8
A patient undergoing a posterior (prone) thoracic surgery will require what airway equipment?
single lumen ETT
What does supine laparotomy mean for an anterior lumbar spine procedure?
pt is supine + a surgical incision into the abdominal cavity
What preop medication should a patient receive if procedure requires the prone position?
anti-sialogogue
- scope patch, glycopyrrolate
glyco safer in elderly (does not cross BBB = less confusion)
After a patient has been turned prone and anes circuit is reconnected, what should you check?
assess for BL breath sounds
You notice the patient has periorbital &/or circumoral edema after being prone for the procedure, this may also indicate:
likely vocal cords also have edema –> caution with extubation (may need to go to ICU and keep intubated until edema subsides)
If using a wilson frame what should you check on the patient?
- males = genitalia
- females = breasts
**free from pressure
Where should arms be if patient is in the prone position?
superman or surrender position with <90 degree adduction
Abdominal pressure from prone position can lead to:
- increased intrathoracic pressure
- decreased FRC & pulm compliance
- decreased venous return
- increased bleeding from epidural vein pressure
What’s a major complication for pts when going prone?
POVL - postop visual loss
What are 3 causes of POVL?
- ischemic optic neuropathy (ION)
- retinal artery/vein occlusio
- cortical brain ischemia
Cause of POVL that can occur without any pressure on the eyes?
ION - ischemic optic neuropathy
** blood loss >1000mL, long surgery >6hrs, male, obese, decreased colloid use
How can we prevent ION (ischemic optic neuropathy)?
- head neutral/midline
- blood transfusion/colloids
- minimize intentional hypoT
Cortical brain ischemia can lead to POVL from:
intentional hypotension
Which 2 table frames allow the abdomen to “hang free” = no pressure on abdomen?
- andrew’s frame
- jackson spine table
Prone effects on the cardiovascular system:
- pooling of blood in extremities
- compression of abdominal muscles
- decrease VR/preload, CO, BP
Prone effects on respiratory system:
- compression of abdomen & thorax
- decrease total lung compliance
- increase WOB
Prone effects on neuro system?
extreme head rotation = decrease venous drainage & CBF
What is the most stable prone positioning device?
Mayfield tongs (pins in head)
What should you have ready to prepare for possible blood loss & transfusion in a spine case?
- 2 large bore PIVs
- 2 units PRBCs in OR cooler
- blood tubing primed & set up in blood warmer
What is a cell saver?
“Cell savers” are instruments that collect blood lost during surgery. The RBCs are washed with normal saline and concentrated to make an approximate 225 mL unit with a hematocrit of ~ 55%. RBC units can be either directly transfused into the patient or washed again and stored
What is the ABL formula?
(Initial Hct - target Hct) / initial Hct
When EBL is anticipated to be 500-1000mL, what can be done preoperatively?
autologous blood donation 2-4 wks prior
Autologous blood donation is contraindicated in:
significant cardiac disease & infection
Tranexemic acid (TXA) dosages:
10 mg/kg IV bolus
gtt: 2 mg/kg/hr
**max = 2.5g
Aminocaproid acid (Amicar) dosages:
**not as common anymore
100 mg/kg IV bolus
gtt: 10-15 mg/kg/hr
This is done in shoulder & hip surgeries but is not recommended for spinal surgeries d/t risk of end-organ ischemia:
intentional hypotension
**surgeon may still request it
used to assess/preserve sensory & motor neurological function during spine procedures?
neurophysiologic monitoring
- SSEP
- MEP
- EMG
SSEP stands for:
somatosensory evoked potential
MEP stands for:
motor evoked potential
What does SSEP monitor?
the dorsal (afferent) column pathways of the spinal cord that are responsible for proprioception & vibration
**impulse comes from peripheral nerve & measured centrally
What does MEP monitor?
the anterior (efferent) portion of spinal cord
**impulse triggered in brain and monitored in specific muscle groups
These are adverse effects of which neurophysiological monitoring:
- cognitive defects
- seizures
- intraop awareness
- scalp burns
- cardiac arrhythmia’s
- bite injuries
MEPs
MEP monitoring should be avoided in what 3 main patients?
- active seizures
- vascular brain clips (heat)
- cochlear implants
monitors nerve root injury during pedicle screw placement & nerve decompression:
EMG - electromyogram
describes the signal strength
AMPLITUDE
the time it takes for a signal to travel through spinal cord
LATENCY
Name 6 cofounding factors that can affect amplitude & latency of neuro monitoring?
o Hypotension
o Hypothermia
o Hypocarbia
o Hypoxia
o Anemia
o Anesthetics
How do volatile agents affect amplitude & latency of neuro monitoring?
dose dependent (keep at 0.5 MAC or less)
- decrease in amplitude
- increase in latency
Which anesthetic agent should be eliminated with MEP monitoring?
Nitrous Oxide
Best anesthetic option for procedures requiring neuro monitoring?
TIVA - opioids, ketamine, versed
**but MEPs are depressed with propofol
If performing MEPs, what meds should be avoided?
- NMBA (but ok for induction)
- propofol
If there are acute changes in amplitude/latency then:
STOP surgery
Spine surgery pts may require postop ventilation if:
- long case (>4 hrs = prone/airway edema)
- thoracic cavity invasion
- EBL >30ml/kg or > 2L
- facial/laryngeal edema
- preop VC < 30-35% of predicted
How do you assess for laryngeal edema if pt has facial swelling after being prone in a spine case?
deflate ETT cuff –> check for leak
– if no cuff leak = airway edema = keep intubated & go to ICU
Caution with this multimodal analgesic in postop spine cases:
NSAIDs = bleeding
What are some multimodal analgesics for postop pain mgmt for spine cases?
- multimodal
- systemic opioids (PCA)
- LA infiltration wound
- intrathecal (spinal) morphine: 0.1-0.2 mg + LA
- continuous epidural infusion
- erector spinae block
What’s the dose of epidural hydromorphone PF (preservative free)?
0.5 - 1 mg
What spine procedure has the highest risk for VAE?
LAMINECTOMY
** b/c large amount of exposed bone & surgical site is above heart
Signs of VAE intraop?
unexplained hypotension
increased end-tidal nitrogen
decreased ETCO2
