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Study raises awareness of rare but dangerous complication during pars plana vitrectomy
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Pars plana vitrectomy is a low-risk procedure, but some studies published over the past decade have identified cases of sudden death during the procedure.
There have been a number of cases over the past 10 years reported in both ophthalmology and anesthesiology journals of patients suddenly dying while undergoing pars plana vitrectomy. These incidents may be due to air being infused into the choroidal space and exiting through the vortex veins, Steven I. Gayer, MD, MBA, told Ocular Surgery News.
Gayer and colleagues published a study in American Journal of Ophthalmology examining the phenomenon.
“Our study is an in vivo demonstration showing that during pars plana vitrectomy, air can be channeled into the suprachoroidal space and then onward into the central circulation, filling the heart, disrupting cardiac blood flow and cardiac output, and causing death. This can happen very quickly. Using transesophageal echocardiography, we detected air less than 30 seconds after increasing infusion pressure to 60 mm Hg,” he said.
In their in vivo surgical study on porcine eyes, Gayer and colleagues noted end-tidal carbon dioxide declined precipitously, followed by hypotension and electrocardiography changes in the animal subjects.
“During modern vitrectomy, air is typically infused through the infusion cannula at a designated pressure. However, the volume of air delivered is not regulated or measured. Small-gauge infusion cannulas are not typically sutured and may be at risk for dislodgment during vitrectomy, resulting in the entrance of the cannula tip into the suprachoroidal space,” Gayer and colleagues wrote.
These results were similar to a 2014 study published in British Journal of Ophthalmology by Morris and colleagues, Gayer said.
Morris and colleagues created extensive choroidal detachment in four donor eyes and found that eyes with open vortex veins demonstrated rapid air extravasation/bubbling, while eyes with clamped vortex vein stumps showed no air bubbling.
The in vitro study demonstrated that air could be infused into the choroidal space and exit through the vortex veins.
“More insidious, and of even greater concern, is the possible creation of choroidal detachment by inadvertent suprachoroidal air infusion during vitrectomy performed for more common conditions, such as macular hole and retinal detachment. Air under continuous pressure might then enter the systemic venous circulation through torn vortex vein ampullae, at a rate sufficient to quickly block pumping action of the heart, or to cause fatal emboli into the arterial circulation through a patent foramen ovale,” Morris and colleagues wrote in the study.
Ophthalmologists, anesthesiologists and operating room personnel may not be ready for this potentially dangerous complication. Most retinal surgeries are typically performed in an ambulatory surgery center, Gayer said, and these facilities may not be equipped for effective resuscitation from profound venous air embolism.
“Vitreoretinal surgeons must be aware of the potential for this rare phenomenon and ensure confirmation of the position of the infusion cannula prior to and during air infusion throughout vitrectomy. Anesthesiologists must be attentive to sudden changes in physiologic parameters that may be indicative of venous air embolism,” Gayer said. – by Robert Linnehan
- References:
- Gayer S, et al. Am J Ophthalmol. 2016;doi:10.1016/j.ajo.2016.06.027.
- Morris RE, et al. Br J Ophthalmol. 2014;doi:10.1136/bjophthalmol-2013-303367.
- For more information:
- Steven I. Gayer, MD, MBA, can be reached at Department of Anesthesiology, University of Miami Miller School of Medicine, 1611 NW 12th Ave., Miami, FL 33136; email: sgayer@med.miami.edu.
Disclosure: Gayer reports no relevant financial disclosures.