Central Retinal Artery Occlusion (CRAO)

58yF with hx of CAD, DM, HTN, HLD, a-fib presents to the ED with an eye complaint - she can barely count fingers out of her left eye since this morning.

CRAO presents as abrupt and painless unilateral vision loss. It is the ophthalmic equivalent of a CVA with ischemia of the retina, and has the same risk factors. The underlying cause can be an embolus, thrombus, or vasospasm. Consider temporal arteritis in the elderly (ESR/CRP, jaw claudication, temporal tenderness). The differential for monocular painless vision loss includes occipital stroke, retinal detachment, CRVO, complex migraine.

Fundoscopically, you will see a cherry red spot, vascular box-carring, and a pale optic nerve.  Aside from decreased visual acuity, they may have a afferent pupillary defect on exam.

From symptom onset, there is a 90 minute window before permanent damage starts. First, call ophthalmology emergently. Then, there a number of agents and maneuvers, none of which have been proven to improve outcomes.

Dislodge embolus - Direct digital pressure through closed eyelid for 10 seconds with sudden release for 5 seconds, continue for 15 minutes

Dilate artery - Carbogen(5% CO2, 95% O2), breathing into a paper bag, nitroglycerin

Reduce IOP - topical timolol, IV acetazolamide or mannitol, anterior chamber paracentesis

However, HBOT has shown promising results and should be considered if the duration of symptoms is less than 12 hours as CRAO has a poor overall prognosis.

Sources

Rosen's

Rosh Review

emDocs: CRAO

LIFTL: Ophthamology Befuddler Medscape: CRAO

Emergency Medicien Cases: Nontraumatic Eye Emergencies

Inferior Shoulder Dislocation

Inferior shoulder dislocation (luxatio erecta) can occur from an axial load to an outstretched arm. Imagine a swimmer hitting the side of a pool with his arm in front. Also this can occur from forced hyperabduction (grabbing something while falling). Clinically, you will notice the patient with their arm over their head and the elbow bent (fixed abduction). You may feel the humeral head in the axilla/lateral chest wall.

X-rays will show the humeral head inferior to the glenoid.

To reduce these dislocations, after procedural sedation, apply traction upwards and laterally (axis of the humerus), with counter-traction. Then, put on a splint and all patients get ortho follow-up. Do not attempt reduction if there is accompanying humeral fracture or vascular injury. A great reduction video by my former attending Dr.Mellick.

 

Although inferior dislocations are rare (<1%), they have the greatest incidence of neurovascular injury. Axially nerve palsy is frequently present but resolves after reduction. If vascular compromise is suspected, emergent ortho and vascular consultation is indicated. Other complications include inferior capsule tear and rotator cuff disruption.

Sources

Ortho Bullets; Luxatio Erecta

WikiEM: Inferior Shoulder Dislocation

Medscape: Shoulder Dislocation

Radiopaedia: Inferior shoulder dislocation

Rosh Review

Local Anesthetic Systemic Toxicity (LAST)

So a guy comes in with 16 superficial stab wounds overnight and you get to be the lucky resident to sew him up (true story). Halfway through, he starts complaining his mouth is numb (this part didn't happen). What do you do? LAST can occur from three important etiologies - direct systemic injection, accumulation from multiple injections, or injection into a highly vascularized area. Most importantly, prevent this from happening by knowing your max dose, aspirating before injecting, and asking about symptoms.

Remember local anesthetics are sodium channel blockers, so when introduced systemically cause cardiac and neuro toxicity.

First, stop injecting the patient. Then,

A - You may need to intubate. B - Give 100% FiO2 and hyperventilate as acidosis, hypoxemia can push this syndrome into cardiac arrest. C - Hypotension should be treated with IVF and push-dose pressors (epi). In arrest, high-quality CPR should be continued for a while as these anesthetics are lipid soluble and take time to redistribute. Consider pacing and ECMO. D - Seizures can occur and benzodiazepines are the treatment, as usual.

If the patient has an arrhythmia, hemodynamic instability, prolonged seizure, or rapid progression of symptoms, break out the 20% intralipid. Call pharmacy/look up the dose - 1 ml/kg over 1 minute q3m x3 and then 0.25 ml/kg/min. Theoretically, lipid emulsion therapy works by drawing anesthetic out of the plasma.

Sources

Rebel EM: http://rebelem.com/local-anesthetic-systemic-toxicity-last/

LITFL: Local Anesthetic Toxicity

Wiki EM: Local Anesthetic Systemic Toxicity

Kapitanyan, R. Local Anesthetic Toxicity. Medscape http://emedicine.medscape.com/article/1844551-treatment#d1