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      The Doctor’s Advocate | Fourth Quarter 2012


       
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      Postoperative Visual Loss: A Catastrophic Complication

      by Susan K. Palmer, MD, Anesthesia Consultant

      The Anesthesia Patient Safety Foundation (APSF) recently held a multidisciplinary invitational conference to discuss information and gather opinions about the possible causes of and potential preventive strategies for postoperative visual loss (POVL). The American Society of Anesthesiologists (ASA) Postoperative Visual Loss Registry was studied, the results presented, and the recent literature reviewed.

      Strokes or hypoxic-ischemic central nervous system (CNS) events are well-known complications of cardiac surgery. Complete or partial loss of vision after surgery involving cardiac bypass has, in the past, been grouped with other CNS injuries. Since the 1990s, however, there has been an increase in the number of cases of complete or partial vision loss associated with other surgeries, such as prone back surgery, extreme head-down pelvic surgery, and orthopedic surgeries.1

      Unlike the strokes associated with cardiac surgery, most of these more recently reported cases have not been associated with embolic phenomena or global CNS injuries. The recent cases involve rather specific ischemia and edema of the optic nerves. The number of these cases may be increasing—which, in 1999, caused the ASA to initiate a voluntary reporting registry of POVL cases. That registry has now been studied to compare 80 reported cases of POVL to 315 adult case control subjects selected from 17 different institutions.2

      The probable cause of POVL in many cases has been identified as edema within and around the optic nerve posterior to the retina. This edema can cause an ischemic type of nerve injury that results in loss of vision. This type of vision loss has nothing to do with pressure on the globe of the eye—which can cause blindness based on retinal artery occlusion or retinal vein obstruction. Posterior optic nerve edema can be caused by the prone and the extreme head-down position. Cases of POVL are now being reported for robotic laparoscopic pelvic surgery, which can require long periods in the extreme head-down position while the abdomen is pressurized.

      The recommendations of the APSF conference will be published in the Winter 2013 APSF Newsletter (www.apsf.org). Although the ASA has not yet been able to issue a definitive practice advisory,3 the APSF will publish information identifying higher-risk patients and suggesting possible strategies to reduce the likelihood of POVL.

      Although POVL can occur with any anesthesia and surgery, study of the ASA POVL Registry has identified the following independent risk factors:

      1. Anesthesia duration (odds ratio, 1.39/hr)
      2. Use of Wilson frame (odds ratio, 4.3)
      3. Obesity (odds ratio, 2.83)
      4. Male sex (odds ratio, 2.53)
      5. Blood loss greater than 1 liter (odds ratio, 1.34/liter)
      6. Replacement of blood loss with crystalloid only

      Preliminary considerations for the prevention of POVL, based on what we know so far, include the following:

      1. When possible, keep the patient’s head at or slightly above the heart, especially during prone cases.
      2. Consider staging lengthy complex spine surgery in higher-risk patients.
      3. Consider replacing blood loss with colloids, such as albumin or hetastarch, to avoid using large amounts of crystalloid, which can produce excess edema fluid.
      4. Avoid induced hypotension for high-risk patients.
      5. During robotic surgery requiring severe head-down position, consider a 15- or 20-minute “time out” for head-up positioning if the surgery is going to last more than four hours.

      The APSF may recommend that POVL be included in the surgical and anesthetic consent processes4 for higher-risk patients.

       

      References

      1. Shen Y, Drum M, Roth S. The prevalence of perioperative visual loss in the United States: a 10-year study from 1996 to 2005 of spinal, orthopedic, cardiac, and general surgery. Anesth Analg. 2009;109(5):1534-1545.
      2. Lee L, Roth S,  Todd MM, et al. Risk factors associated with ischemic optic neuropathy after spinal fusion surgery. Anesthesiology. 2012;116(1):15-24.
      3. Apfelbaum JL, Roth S,  Connis RT, et al. Practice advisory for perioperative visual loss associated with spine surgery: an updated report by the American Society of Anesthesiologists Task Force on Perioperative Visual Loss. Anesthesiology. 2012;116(2): 274-285.
      4. Corda DM, Dexter F,  Pasternak JJ, et al. Patients’ perspective on full disclosure and informed consent regarding postoperative visual loss associated with spinal surgery in the prone position. Mayo Clin Proc. 2011;86(9):865-868.

       

      The Doctor’s Advocate is published by The Doctors Company to advise and inform its members about loss prevention and insurance issues.

      The guidelines suggested in this newsletter are not rules, do not constitute legal advice, and do not ensure a successful outcome. They attempt to define principles of practice for providing appropriate care. The principles are not inclusive of all proper methods of care nor exclusive of other methods reasonably directed at obtaining the same results.

      The ultimate decision regarding the appropriateness of any treatment must be made by each healthcare provider in light of all circumstances prevailing in the individual situation and in accordance with the laws of the jurisdiction in which the care is rendered.

      The Doctor’s Advocate is published quarterly by Corporate Communications, The Doctors Company. Letters and articles, to be edited and published at the editor’s discretion, are welcome. The views expressed are those of the letter writer and do not necessarily reflect the opinion or official policy of The Doctors Company. Please sign your letters, and address them to the editor.


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