Prolonged Prone Ventilation Could Put COVID Patients at Risk for Orbital Compartment Syndrome

By Scott Baltic

December 07, 2020

NEW YORK (Reuters Health) - COVID-19 patients who have to remain in a prolonged prone position because of ventilation during intensive care appear to be at risk for elevated intraocular pressure (IOP), a new case series from the U.S. suggests.

The elevated IOP seems to arise from direct pressure on the orbit and the globe and is associated with periorbital edema, which could potentially lead to orbital compartment syndrome (OCS), the authors of the new report say.

"OCS is a vision-threatening elevation of intra-orbital pressure which exceeds the vascular perfusion pressure of the ophthalmic artery," Dr. Howard Pomeranz of the department of ophthalmology at Northwell Health, in Great Neck, New York, told Reuters Health by email.

He added that OCS is an ophthalmic emergency and can result in ischemia and irreversible vision loss if not corrected emergently.

In the course of one week, 16 patients in the intensive-care unit (ICU) at Northwell Health received prone-position ventilation for hypoxemic respiratory failure caused by COVID-19. Of these, four were in a prone position for 18 straight hours out of every 24 hours. All four were seen to have periorbital edema, prompting eye examinations.

Two of these patients had optic-disc edema and retinal hemorrhages, possibly consistent with a papillophlebitis. Both were also found to have substantially elevated intraocular pressure when in the prone (versus supine) position, as well as optic-disc edema and retinal hemorrhages.

When the ICU patients were positioned prone, their heads were rotated 45 degrees laterally to accommodate the endotracheal tube, making one eye the dependent/lower eye.

The first of the two patients was a man in his early 50s with no significant medical history. Perioribital edema was observed around his right (dependent) eye.

At the time the eye examination was performed, he had undergone nine sessions of 18-hour ventilation in the prone position. His IOP was 10 mmHg in the right eye and 11 mmHg in the left eye in the supine position and 30 mmHg in the left eye in the prone position (his right eyelid was in contact with the pillow, preventing safe measurement of IOP in the right eye).

Fundus examination found his cup-disc ratio was 0.3 bilaterally. The right optic disc had sharp margins with nerve-fiber-layer hemorrhages near the optic disc. The left optic disc had mild inferior margin elevation, with a few hemorrhages in the mid-periphery.

The second patient was a man in his mid-40s with non-insulin-dependent type-2 diabetes and periorbital edema around his right eye (the dependent eye). At the time of initial eye examination, he had had a total of four sessions of 18-hour ventilation in the prone position.

His IOP was 10 mmHg in each eye in the supine position and 26 mmHg in the right (dependent) eye and 20 mmHg in the left eye in the prone position.

Fundoscopy found bilateral inferior optic-disc elevation with associated flame-shaped hemorrhages. The cup-disc ratio was 0.3 bilaterally.

On follow-up fundoscopy six days later (after two additional 18-hour sessions of prone ventilation), progression of retinal hemorrhages near both optic discs was seen.

Because all four of the patients showing periorbital edema were deeply sedated, their visual acuity could not be assessed.

The researchers concluded that the ophthalmic findings for the two patients "are most consistent with papillophlebitis, possibly related to the combined effects of increased orbital venous pressure during prolonged prone positioning and COVID-19-associated coagulopathy."

They cautioned, however, that their findings "do not provide strong evidence that the prone position itself is the cause for the fundus findings. Patients who are placed in the prone position for long periods of time are more ill, have more hypoxia, and are in a greater inflammatory state, which could also be contributing to these findings."

Nonetheless, they say their findings do call for awareness of potential ophthalmic complications, including vision loss, in severely ill patients with COVID-19.

Dr. Pomeranz suggested that a patient's eyes "need to be cushioned properly to prevent compression when the head is turned to the side in the prone position" for long periods.

In addition, the authors recommended maintaining the patient's head position above heart level when possible and considering a fundus examination to identify any optic disc or retinal abnormalities in prone-positioned ICU patients.

Dr. Rahul Khurana, a spokesman for the American Academy of Ophthalmology, told Reuters Health in a phone interview that "This kind of awareness (of ophthalmic risk) is very important," especially giving the accelerating coronavirus pandemic.

He cautioned that a small case series like this can show only association, not causation, particularly because the symptoms could have been connected to coagulopathy caused by COVID infection. Still, he added, taking more precautions makes sense, until further research can indicate how common these issues are.

Among those precautions, Dr. Khurana said, is that ICU personnel need to monitor prone patients for ocular swelling. This is a particularly concerning situation, he explained, because the patient is sedated and thus unable to report vision issues.

Changes in clinical practice, he concluded, "start with good clinical observations like this."

SOURCE: JAMA Ophthalmology, online November 19, 2020.