OCS

Q: You have been called to evaluate a patient's eyes who is on high PEEP. Nurse at the start of her shift noticed patient's eyelids tight and "rock hard". On exam, you found periorbital swelling, proptosis, diffuse subconjunctival hemorrhage, and inability to push the eye deeper into the orbit. What is your diagnosis?


Answer: Orbital compartment syndrome (OCS) 


OCS is an ophthalmologic emergency. Head of the bed should be immediately elevated to 45 degrees and Opthalmology should be called for immediate lateral canthotomy and inferior cantholysis. If an ophthalmology service is not available, a physician experienced with such procedure should take the charge, as permanent blindness is imminent with delay in care. Pressure on the optic nerve can cause irreversible ischemia. 

Classic findings of OCS are an acute onset of decreased vision, diplopia, and eye pain, which may be lacking in ICU patients, further increasing the risk of blindness without bedside staff even aware of it. Physical findings include periorbital swelling, an afferent pupillary defect, proptosis, diffuse subconjunctival hemorrhage, very tight eyelids (feel like rock hard), and an inability to push the eye deeper into the orbit, called as a tight orbit or decreased retropulsion. 

All attempts should be made to avoid an increase of OCS like decreasing PEEP to the point where hypoxemia can be sustained, avoiding cough, pain control, decreasing nausea/vomiting (OCS can induce it) and avoiding any cause which leads to increase intrathoracic or intraabdominal pressure.

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References:

1. Lima V, Burt B, Leibovitch I, et al. Orbital compartment syndrome: the ophthalmic surgical emergency. Surv Ophthalmol 2009; 54:441.  

2. Sun MT, Chan WO, Selva D. Traumatic orbital compartment syndrome: importance of the lateral canthomy and cantholysis. Emerg Med Australas 2014; 26:274.