Practice Advisory for Perioperative Visual Loss Associated with Spine Surgery 2019

Practice advisories are systematically developed reports that are intended to assist decision-making in areas of patient care. Advisories provide a synthesis of scientific literature and analysis of expert opinion, clinical feasibility data, open forum commentary, and consensus surveys. Practice advisories developed by the American Society of Anesthesiologists (ASA) are not intended as standards, guidelines, or absolute requirements, and their use cannot guarantee any specific outcome. They may be adopted, modified, or rejected according to clinical needs and constraints, and they are not intended to replace local institutional policies. Practice advisories summarize the state of the literature and report opinions obtained from expert consultants and ASA members. They are not supported by scientific literature to the same degree as standards or guidelines because of the lack of sufficient numbers of adequately controlled studies. Practice advisories are subject to periodic revision as warranted by the evolution of medical knowledge, technology, and practice. This document updates the “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,” adopted by the ASA in 2011 and published in 2012.1 Methodology Definition of Perioperative Visual Loss Perioperative visual loss after spine surgery is a rare and disabling complication.2–4 For this Advisory, “perioperative visual loss” refers to permanent impairment or total loss of sight associated with a spine procedure during which general anesthesia is administered. The perioperative period includes the time from the immediate preoperative assessment through discharge from the acute healthcare facility. Conditions addressed in this Advisory include posterior ischemic optic neuropathy, anterior ischemic optic neuropathy, central and branch retinal artery occlusion, cerebral visual loss, and posterior reversible encephalopathy syndrome. Anterior ischemic optic neuropathy damages the front of the optic nerve (the optic nerve head or optic disc), whereas posterior ischemic optic neuropathy injures the portion of the optic nerve behind the eye.5 “High-risk patients” are defined for this Advisory as those who undergo spine procedures while positioned prone and who have prolonged procedures, experience substantial blood loss, or both.† Purpose of the Advisory The purpose of this Advisory is to enhance awareness and reduce the frequency of perioperative visual loss during and after spine surgery. Focus of the Advisory This Advisory focuses on the perioperative management of patients who are undergoing spine procedures while they are positioned prone and receiving general anesthesia. This Advisory does not address the perioperative management of patients who receive regional anesthesia or sedation. This Advisory also does not include other causes of visual loss. It does not include nonspine surgical procedures (e.g., cardiac surgery, radical neck dissection). In addition, this Advisory does not apply to spine surgery patients younger than 12 yr of age. Application of the Advisory This Advisory is intended for use by anesthesiologists, neurosurgeons, neuro-ophthalmologists, and all other individuals who deliver or who are responsible for anesthesia or perioperative care. These individuals may include orthopedic surgeons, neurosurgeons, ophthalmologists, neuro-ophthalmologists, neurologists, nurse anesthetists, perioperative nurses, operating room nurses, and anesthesiology assistants. The Advisory also may serve as a resource for other physicians, nurses, and healthcare professionals who manage anesthetized patients. Task Force Members and Consultants In 2017, the ASA Committee on Standards and Practice Parameters requested that this Advisory be updated. This Advisory update is a revision developed by an ASA-appointed task force of 16 members from various geographic areas of the United States, consisting of six anesthesiologists, four neuro-ophthalmologists, two neurosurgery and two orthopedic spine surgeons, and two methodologists. Seven physicians served as official liaisons from national organizations including the North American Neuro-Ophthalmology Society (NANOS), North American Spine Society (NASS), Society for Neuroscience in Anesthesiology and Critical Care (SNACC), and the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Joint Section on Disorders of the Spine and Peripheral Nerves. Conflict of interest documentation regarding current or potential financial and other interests pertinent to the practice guideline were disclosed by all task force members and managed. The task force developed this Advisory by means of a six-step process. First, criteria for evidence associated with perioperative visual loss were established. Second, original published research studies relevant to perioperative visual loss were reviewed and evaluated. Third, a panel of expert consultants was asked to (1) participate in opinion surveys concerning the effectiveness and safety of various methods and interventions that might be used for prevention of perioperative visual loss, and (2) review and comment on a draft of the Advisory developed by the task force. Fourth, survey opinions about the Advisory recommendations were solicited from a random sample of active ASA members and participating medical specialty societies. Fifth, the consultants were surveyed to assess their opinions on the feasibility of implementing the advisory. Sixth, all available information was used to build consensus within the task force to finalize the advisory. A summary of recommendations may be found in appendix 1. Availability and Strength of Evidence Preparation of this updated advisory followed a rigorous methodologic process. Evidence was obtained from two principal sources: scientific evidence and opinion-based evidence. Scientific Evidence Scientific evidence used in the development of this advisory is based on cumulative findings from literature published in peer-reviewed journals. Literature citations are obtained from healthcare databases, direct internet searches, task force members, liaisons with other organizations, and manual searches of references located in reviewed articles. Findings from the aggregated literature are reported in the text of this advisory by evidence category, level, and direction. Evidence categories refer specifically to the strength and quality of the research design of the studies. Category A evidence represents results obtained from randomized, controlled trials, and category B evidence represents observational results obtained from nonrandomized study designs or randomized, controlled trials without pertinent comparison groups. When available, category A evidence is given precedence over category B evidence for any particular outcome. These evidence categories are further divided into evidence levels. Evidence levels refer specifically to the strength and quality of the summarized study findings (i.e., statistical findings, type of data, and number of studies reporting/replicating the findings). In this document, only the highest level of evidence is included in the summary report for each intervention–outcome pair, including a directional designation of benefit, harm, or equivocality. Category A. Randomized, controlled trials report comparative findings between clinical interventions for specified outcomes. Statistically significant (P < 0.01) outcomes are designated as either beneficial (B) or harmful (H) for the patient; statistically nonsignificant findings are designated as equivocal (E).‡ Level 1: The literature contains a sufficient number of randomized, controlled trials to conduct meta-analysis, and meta-analytic findings from these aggregated studies are reported as evidence. Level 2: The literature contains multiple randomized, controlled trials, but the number of trials is not sufficient to conduct a viable meta-analysis for the purpose of these Guidelines. Findings from these trials are reported separately as evidence. Level 3: The literature contains a single randomized, controlled trial, and findings from this study are reported as evidence. Category B. Observational studies or randomized, controlled trials without pertinent comparison groups may permit inference of beneficial or harmful relationships among clinical interventions and clinical outcomes. Inferred findings are given a directional designation of beneficial (B), harmful (H), or equivocal (E). For studies that report statistical findings, the threshold for significance is P < 0.01. Level 1: The literature contains nonrandomized comparisons (e.g., quasiexperimental, cohort [prospective or retrospective], or case–control research designs) with comparative statistics among clinical interventions for a specified clinical outcome. Level 2: The literature contains noncomparative observational studies with associative statistics (e.g., correlation, sensitivity, and specificity). Level 3: The literature contains noncomparative observational studies with descriptive statistics (e.g., frequencies, percentages). Level 4: The literature contains case reports. Insufficient Literature. The lack of sufficient scientific evidence in the literature may occur when the evidence is either unavailable (i.e., no pertinent studies found) or inadequate. Inadequate literature cannot be used to assess relationships among clinical interventions and outcomes because a clear interpretation of findings is not obtained because of methodologic concerns (e.g., confounding of study design or implementation) or the study does not meet the criteria for content as defined in the “Focus” of the advisory. Opinion-based Evidence All opinion-based evidence (e.g., survey data, open forum testimony [from original advisory], internet-based comments, letters, and editorials) relevant to each topic was considered in the development of these guidelines. However, only the findings obtained from formal surveys are reported in the document. Opinion surveys were developed by the task force to address each clinical intervention identified in the document. Identical surveys were distributed to expert consultants and a random sample of members of the participating organizations. Expert and Participating Membership Opinion Surveys. Survey findings from task force–appointed expert consultants, a random sample of the ASA membership, and membership samples from NANOS, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves are fully reported in this document. Survey responses were recorded using a five-point scale and summarized based on median values. Strongly Agree: Median score of 5 (at least 50% of the responses are 5) Agree: Median score of 4 (at least 50% of the responses are 4 or 4 and 5) Equivocal: Median score of 3 (at least 50% of the responses are 3, or no other response category or combination of similar categories contains at least 50% of the responses) Disagree: Median score of 2 (at least 50% of responses are 2 or 1 and 2) Strongly Disagree: Median score of 1 (at least 50% of responses are 1) Informal Opinion. Open forum testimony obtained during development of the original advisory, internet-based comments, letters, and editorials are all informally evaluated and discussed during the formulation of guideline recommendations. When warranted, the task force may add educational information or cautionary notes based on this information. Advisory Evidence and Recommendations Preoperative Patient Evaluation and Preparation Literature Findings. Comparative studies are insufficient to evaluate the impact of conducting an ophthalmic examination. Studies with observational findings indicate that certain conditions, including preoperative anemia, vascular risk factors (e.g., hypertension, diabetes, peripheral vascular disease, coronary artery disease, previous stroke, carotid artery stenosis), obesity, and tobacco use, among other preoperative characteristics (e.g., age, male sex, and diabetic retinopathy), may be associated with perioperative visual loss (Category B2-H evidence).3,6–10§ Two retrospective descriptive studies also indicate that perioperative visual loss may occur in patients with the above conditions (Category B3-H evidence).4,11 Case reports indicate that perioperative visual loss may occur in patients whose medical history includes the listed preoperative conditions listed above (Category B4-H evidence).12–34‖ Although a small cup-to-disc ratio may render the axons of the optic nerve more susceptible to injury, the literature is insufficient to evaluate the role of optic nerve head anatomy as a risk factor for perioperative anterior ischemic optic neuropathy or support routinely conducting a preoperative examination of the cup-to-disc in spine surgery patients.5,35 One observational study reported that 86% of patients undergoing spine surgery in the prone position prefer to be informed of the risk of visual loss (Category B3-B evidence).36 The literature is insufficient to evaluate whether or not glaucoma is a risk factor for perioperative visual loss. Survey Findings. The consultants and members of ASA, NANOS, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves strongly agree with the recommendation to review a patient’s preoperative history and perform an appropriate examination to identify patients with preoperative conditions such as preoperative anemia, vascular risk factors (e.g., hypertension, diabetes, peripheral vascular disease, coronary artery disease, previous stroke, carotid artery stenosis), obesity, and tobacco use. Consultants and members of the participating organizations agree with the recommendation to inform patients that certain preoperative conditions may increase their risk of perioperative visual loss in spine surgery. The consultants and members of ASA and NANOS strongly agree, and members of SNACC and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation to inform patients in whom prolonged procedures, substantial blood loss, or both are anticipated that there may be an increased risk of perioperative visual loss. Finally, consultants and members of ASA, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation to determine on a case-by-case basis whether or not to inform patients who are not anticipated to be “high-risk” for visual loss; members of NANOS were equivocal. Advisory Recommendations for Preoperative Patient Evaluation and Preparation Review a patient’s preoperative history and perform an appropriate examination to identify patients with conditions such as preoperative anemia, vascular risk factors (e.g., hypertension, diabetes, peripheral vascular disease, coronary artery disease, previous stroke, carotid artery stenosis, tobacco use), and obesity. Inform patients that certain preoperative conditions may increase their risk of perioperative visual loss in spine surgery. These include, but are not limited to, those who are male, obese, or have vascular disease risk factors such as hypertension and peripheral vascular disease. Inform patients in whom prolonged procedures, substantial blood loss, or both are anticipated that there may be an increased risk of perioperative visual loss.# Determine on a case-by-case basis whether or not to inform patients who are not anticipated to be “high-risk” for visual loss. Intraoperative Intraoperative management of (1) blood (2) management of blood loss and of use of patient and head and of surgical Literature Findings. One retrospective descriptive and two retrospective observational studies reported equivocal findings regarding the of and perioperative ischemic optic neuropathy (Category Case reports visual loss after procedures in which (Category B4-H Although case reports perioperative visual loss after procedures in which was for patients without or for patients with (Category the literature is equivocal on whether or not the risk of ischemic optic neuropathy is increased as a of either or from the use of preoperative or (Category Survey Findings. The consultants and members of ASA, NANOS, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves strongly agree with the recommendation to blood in patients. The consultants and members of ASA and SNACC strongly agree and members of NANOS and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation to assess the patient’s blood on a case-by-case Consultants and members of the participating organizations agree with the recommendation to determine on a case-by-case basis be used in patients. The consultants and members of ASA, NANOS, and SNACC strongly agree, and members of AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation to for the of preoperative hypertension, degree of the preoperative use of and the patient’s risk of using in a Consultants and members of ASA, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves strongly agree and members of NANOS agree with the recommendation to with the whether is Consultants and members of ASA and SNACC strongly agree and members of NANOS and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation to at levels in patients to to The consultants and members of the participating organizations agree with the recommendation to use in patients only when the and agree that use is and strongly agree with the recommendation to prolonged significant in blood of Loss and of Literature Findings. Two observational studies report that blood loss and of surgery are associated with perioperative visual loss (Category B2-H descriptive observational studies indicate that perioperative visual loss may occur with substantial blood loss, prolonged or both (Category B3-H Case reports indicate that perioperative visual loss may occur after prolonged substantial blood or (Category B4-H One case report that visual loss in a spine surgery patient when was the procedure (Category Although comparative studies are insufficient to evaluate the impact on visual loss of the of and on the of perioperative visual loss, case–control study reported that the of in the total no statistically significant on ischemic optic neuropathy, whereas as a of total was associated with a risk of ischemic optic neuropathy (Category Case reports indicate that visual loss may occur when these are used (Category Survey Findings. The consultants and members of ASA, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves strongly agree and members of NANOS agree with the recommendation to or during surgery in patients who experience substantial blood loss. Consultants and members of the participating organizations strongly agree with the recommendation to use of blood as Consultants and members of ASA, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation that or or in combination may be used to of members of NANOS are equivocal. of Literature Findings. Comparative studies are insufficient to evaluate the impact on perioperative visual loss from perioperative of during spine surgery. One retrospective observational study reported equivocal findings for perioperative use when patients with perioperative visual loss were with patients without perioperative visual loss (Category One case report that perioperative visual loss may occur in spine surgery patients in whom was with multiple of and (Category Survey Findings. Consultants and members of ASA and SNACC strongly agree and members of NANOS and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation that may be used on a case-by-case basis when is to for Patient and Literature Findings. One retrospective study perioperative visual loss patients with patients without perioperative visual loss reported a significant between the use of the and ischemic optic neuropathy (Category B2-H observational studies obtained from institutional also perioperative visual loss when a patient is positioned prone on positioned prone on a or when the patient’s head is supported by various such as head or (Category B3-H Case reports indicate that patient in direct to the (e.g., from the use of a or other may the of perioperative visual loss from retinal artery in spine surgery patients (Category B4-H Comparative studies are insufficient to evaluate whether the patient’s head the with the head in or is associated with perioperative visual loss. the during spine surgery may assist in the of Although there are a number of head that the to be for when the patient is positioned the literature is insufficient to support of any head or to a particular frequency of Survey Findings. The consultants and members of SNACC strongly agree and members of ASA, NANOS, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation to position the patient that the head is level with or than the of the when Consultants and members of ASA and SNACC strongly agree and members of NANOS and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree with the recommendation to the patient’s head in a position (e.g., without significant neck or when Consultants and members of the participating organizations strongly agree with the recommendation to direct on the to retinal artery Consultants and members of SNACC and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves strongly agree and members of ASA and NANOS agree with the recommendation that a head may be by the spine in patients in whom head is Finally, consultants and members of the participating organizations strongly agree with the recommendation to the position of the during surgery to the head not and there is no of The of spine surgery patients who experience perioperative ischemic optic neuropathy undergo prolonged procedures with substantial blood loss while they are positioned of spine surgical procedures the procedure in two or more as to a single surgical Literature Findings. The literature is insufficient to the impact of surgical on the frequency of perioperative visual loss in spine surgery patients. Survey Findings. The consultants and members of ASA, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves strongly agree and members of NANOS agree with the recommendation that spine procedures may be used on a case-by-case basis for patients. Advisory Recommendations for Intraoperative the patient’s blood blood in patients. Determine on a case basis whether be used in patients. for the of preoperative hypertension, degree of the preoperative use of and the patient’s risk of using in a with the whether is at levels in patients to to in patients only when the and agree that use is prolonged significant in blood of Loss and of or during surgery in patients who experience substantial blood of blood as or or in combination may be used to of of may be used on a case-by-case basis when is to for Patient and the patient that the head is level with or than the of the when the patient’s head in a position (e.g., without significant neck or when direct on the to retinal artery A head may be by the spine in patients in whom head is the position of the during surgery to the head not and there is no of spine procedures may be used on a case-by-case basis for patients. Literature Findings. The literature is insufficient to evaluate the of a patient’s when the patient The literature is insufficient to evaluate the use of or to causes of visual loss or the of or to optic nerve in perioperative visual loss. A case report of a spine surgery patient with posterior ischemic optic neuropathy that visual after the of increased and blood (Category Two case reports that the visual loss with the of to ischemic optic neuropathy (Category case reports found no visual after the of (Category is insufficient evidence to support the of or in the of ischemic optic to perioperative retinal artery occlusion, the literature is insufficient to support the use of any of this there is no evidence of a role for or in the management of perioperative ischemic optic Survey Findings. The consultants and members of ASA, NANOS, SNACC, and AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves agree that for the conduct an assessment when the patient (e.g., in the or Consultants and members of the participating organizations strongly agree with the recommendation that there is regarding potential visual loss, to an to determine Consultants strongly agree and members of the participating organizations agree with the recommendation that or may be used on a case-by-case basis to causes of visual loss as as to an optic Finally, consultants and members of the participating organizations strongly agree with the recommendation that management may include or and Advisory Recommendations for the of a patient when the patient (e.g., in the or there is regarding potential visual loss, an to determine or may be used on a case-by-case basis to causes of visual loss as as to an optic management may include or and was by the American Society of from of The no and have expert and testimony in of perioperative visual loss on of physicians, and