Author: Michael M. Todd, M.D.
Commentary: Perioperative Visual Loss in Spine Fusion Surgery: Ischemic Optic Neuropathy in the United States from 1998 to 2012 in the Nationwide Inpatient Sample
Anesthesiology 9 2016, Vol.125, 445-448.
THE first description of postoperative visual loss (POVL) in Medline is from 1950. Cases appeared sporadically over the next 30 to 40 yr, mostly related to opthalmalogic procedures, cardiac surgery, and a miscellany of other operations. Some were due to direct eye injuries, but some were due to ischemic optic neuropathy (ION), most commonly reported in association with massive intraoperative hemorrhage and hypotension or radical head and neck surgery. Then, in the early 1990s, cases of ION began to appear after prone spine surgeries. Along with the rapid growth in instrumented spine procedures, the yearly number of publications accelerated dramatically. Some of these publications advanced unsupported theories as to cause and equally unsupported recommendations regarding prevention. In response, the American Society of Anesthesiologists (ASA) made a concerted effort to gather objective information by establishing the POVL Registry in 1999. Over the next few years, information was accumulated that began to shed some light on the problem. For example, case data in the registry effectively eliminated “pressure on the globe” as a major cause of POVL, established the important role of case duration, and raised questions about the specific roles of blood loss, transfusion, hypotension, anemia, etc., strongly supporting a belief in a complex multivariate etiology. Based on this, the ASA published its first Practice Advisory regarding POVL in 2006. Working with data in the registry, the POVL Study Group conducted a multicenter case-matching study intended to better examine risk factors for ION. As expected, multiple factors were found to differ between patients with and without ION, but only six could be identified as independent risk factors in a multivariate model: male sex, obesity, the use of a Wilson frame for positioning, case duration, estimated blood loss (EBL), and the fraction of colloids given as part of non–blood fluid management. Many of these items were incorporated into an updated ASA Practice Advisory in 2012.
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