Trauma and ophthalmic procedures Flashcards
lefort 1 fracture description
horizontal fracture from the maxilla extending from the floor of the nose and hard palate through the nasal septum and pterygoid plates
lefort 2 fracture description
triangular fracture running from the bridge of the nose through the medial and inferior wall of the orbit beneath the zygoma through the lateral wall of the maxilla and the pterygoid plates
lefort 3 fracture description
totally separates the midfacial skeleton form the cranial base, transversing the root of the nose, ethmoid bone, eye orbits, and sphenopalatine fossa
signs of lefort 1 fracture
- malocclusion
- buccal ecchymosis
- epistaxis
- maxillary crepitus
- maxilla mobile
signs of lefort 2 fracture
- midface crepitus
- facial lengthening
- bilateral epistaxis
- infraorbital paresthesia
- ecchymosis
signs of lefort 3 fracture
- caved-in, flattened, or lengthened face
- CSF rhinorrhea
- bilateral epistaxis
- lateral orbital rim defect
- ecchymosis
anesthesia considerations with lefort fractures
- do not nasally intubate a lefort 2 or 3 fracture
- airway edema, pretreat with steroid
- awake extubation, pt will be wired shut
ocular cardiac reflex
- bradycardia, AV block, ventricular ectopy, asystole from manipulation of the eye
- trigeminovagal reflex (ophthalmic division of trigeminal nerve)
- more common in peds vs adults
anesthesia and OCR
- seen during topical and general anesthesia
- less common during retrobulbar blocks
- orbital injections can stimulate
- response worsened by hypoxemia and hypercarbia
treatment of OCR
- stop manipulation of eye
- assess ventilation adequacy
- lido localization or deepen anesthetic
- atropine for bradycardia
- response fatigues with repeated stimulation
IOP
- MAP needs to be > IOP
- high IOP impairs optic nerve function
- volume in eye is relatively fixed except for aqueous fluid and choroid blood volume
normal IOP
- 10-22 mmHg
Arterial pressure and IOP
- sudden increases in BP increase IOP but this soon dissipates d/t drainage system
- sudden decreases, BP<90 will decrease IOP d/t loss of autoregulation
venous pressure and IOP
- increases in CVP, increase IOP more than increases in BP by obstructing drainage
- coughing, straining, breathholding, vomiting
Co2 tension and IOP
- decreased PaCo2 results in decreased IOP from choroidial vasoconstriction
- fast respiratory rate may increase IOP from insufficient drainage
acidosis/ alkalosis and IOP
- metabolic acidosis decreases the choroid vessel volume, decreasing IOP
- metabolic alkalosis increases the choroid volume, increasing IOP
anesthetic agents and IOP
- most lower or have no effect on IOP
- ketamine may increase IOP d/t increased BP
- etomidate is associated with myoclonus
- opioids decrease IOP
muscle relaxants and IOP
- intubation increases IOP if depth is not adequate, regardless of NMB
- nondepolarizing NMB do not alter IOP
- Sch increases IOP
carbonic anhydrase inhibitors (acetazolamide)
- decreases IOP, acts within minutes
osmotic diuretics (mannitol)
- decreases IOP and increases circulating blood volume
- max effect in 35-40 minutes
complications of a retrobulbar block
- hemorrhage is the most common
- proptosis (downward displacement)
- subconjunctival ecchymosis
- arterial injection leads to CNS excitation
retrobulbar block
- IOP monitoring is mandatory
- produces anesthesia of the globe
- akinesia of the extraocular muscle
- decreased production of aqueous humor = decreased IOP
retrobulbar block, injection into optic nerve
- leads to obtundation
- respiratory arrest
- vascular collapse
- contralateral amaurosis (complete lack of vision)
contraindications for RBB
- bleeding disorders
- extreme myopia
- open eye injury (pressure behind the eye, forces contents of eye out the wound)
peribulbar block
- less hemorrhage risk
- longer onset and less complete akinesia
- increase likelihood of ecchymosis
sub-tenon’s block
- no sharp needle, LA placed under tenon’s fascia
- least amount of complications
topical anesthesia medications
- tetracaine 0.5%
- lidocaine 4%
risk of general anesthesia
- emesis from vagal stimulation
- avoid N2O before and after procedure
open globe procedure
- emergent, RSI, GETT
- NDNMB because they don’t increase IOP
- keep pt deep for intubation to not increase IOP
strabismus surgery
- 16% related to muscle disorder (MH risk)
lacrimal apparatus surgery risks
- defective drainage leads to excess tears
- suction well (spasm risk)
