Preanesthesia medical examination is a common procedure performed before ophthalmic surgery. The frequency and characteristics of new medical issues and unstable medical conditions revealed by ophthalmic preanesthesia medical examination are unknown. We conducted a prospective observational study to estimate the proportion of patients with new medical issues and unstable medical conditions discovered during ophthalmic preanesthesia medical examination. Secondary aims were to characterize abnormal findings and assess surgical delay and adverse perioperative events, in relation to findings.
Patients having preanesthesia medical examination, before ophthalmic surgery, were enrolled over a period of 2 years. A review was conducted of historical, physical examination, and test findings from the preanesthesia medical examination.
From review of medical records of 530 patients, 100 patients (19%; 95% CI, 16–23%) were reported by providers to have abnormal conditions requiring further medical evaluation. Of these, 12 (12%) had surgery delayed. Retrospective review of examination results identified an additional 114 patients with abnormal findings for a total of 214 (40%; 95% CI, 36–45%) patients. Among the 214 patients, primary findings were cardiovascular (139, 26%), endocrine (26, 5%), and renal (24, 5%). Complications occurred in 49 (9%; 95% CI, 7–12%) patients within 1 month of surgery.
Ophthalmic preanesthesia medical examination frequently detects new medical issues or unstable existing conditions, which do not typically alter conduct of perioperative procedures or outcomes. However, these conditions are relevant to long-term patient health and should be conveyed to primary care physicians for further evaluation.
The extent to which new medical issues are identified in preanesthesia examinations for ophthalmologic surgery remains unknown
On review of medical records of 530 patients undergoing ophthalmologic surgery, new medical issues were identified by investigators in 40% of patients, with less than half being identified by the original clinicians
Surgery was delayed in only 4% of cases, but many of the identified issues warranted primary care follow-up
PREANESTHESIA medical evaluation is a common procedure performed before ophthalmic surgery. Some states, including Florida, legally require preanesthesia medical examination for surgical centers. ‖ The examination includes a review of the patient’s medical history, a physical examination, and test findings, which are believed to be relevant to surgical risk.1–3 Although it has been generally acknowledged that preoperative history and physical examination reduces surgical hazards, the role of routine testing before ophthalmic surgery has been questioned. Multiple studies have evaluated preoperative testing and found no evidence that it had any effect on perioperative risk.4–6
In recent years, ophthalmologists and physicians at our institution have noted anecdotally that numerous patients were found to have new abnormal examination and test findings on preanesthesia medical examination before ophthalmic surgery. Although these findings may not have direct impact on the upcoming surgery, many are relevant enough to the overall long-term health of the patient to warrant follow-up evaluation.
Previous investigations in this field have established a high prevalence of preexisting medical disease, with up to 38% of preoperative tests being abnormal.4,7–10 However, abnormalities found by ophthalmic preanesthesia medical examination were not further clarified to be new or existing medical conditions.7–10 Moreover, those with existing conditions were not analyzed to distinguish which findings, if any, were different from the patient’s medical history. The prevalence of disease has been high, although the incidence of new or unstable disease at ophthalmic preoperative medical examination has not been described. This subtle but important distinction is further examined by our study, in which we reviewed charts to clarify whether abnormalities found were different from the medical history.
In this study, we report the results of a 2-year study to estimate the incidence of new medical conditions and unstable medical findings revealed by ophthalmic preanesthesia medical examination. The primary aim was to estimate the proportion of patients with new medical issues and unstable medical conditions discovered during ophthalmic preanesthesia medical examination. The secondary aims were to characterize the abnormal findings and to assess surgical delay and adverse perioperative events in relation to ophthalmic preanesthesia medical examination findings.
Materials and Methods
Statement of Ethics
We certify that all applicable institutional and governmental regulations concerning the ethical treatment of human volunteers were followed during the research. The Mayo Clinic Institutional Review Board approved the protocol. The study was funded by a Mayo Clinic Clinical Research grant. This funding source was not involved in study design; in collection, analysis, and interpretation of data; or in approval of publication of the manuscript.
We enrolled patients having preanesthesia medical examination before ophthalmic surgery at Mayo Clinic in Jacksonville, Florida, from June 10, 2009, to February 18, 2011. All ophthalmic surgery patients were eligible for this prospective observational study, and procedure types included cataract, oculoplastic, glaucoma, and retinal surgery. Written informed consent was obtained from all participants before preanesthesia medical examination.
Patients were enrolled in the outpatient setting at this institution, after agreeing to undergo ophthalmic surgery, and referred for a preanesthesia medical examination before elective admission for same-day surgery. These patients were followed up from preanesthesia medical examination to surgery and then for up to 6 months postoperatively by review of their medical chart contained in the Mayo Clinic electronic medical record, which is shared by outpatient and hospital practices.
Although this was a prospective study, data were retrieved retrospectively on prospectively identified patients. In addition to obtaining demographic and history information, patient records were reviewed regarding ophthalmic preanesthesia medical examination findings. Although all preanesthesia medical examination providers were at the same institution, they were not informed of the study. The physician investigators (Drs. Phillips and Bendel) together examined the notes of all ophthalmic preanesthesia medical examination providers, which share a common format, regarding new or unstable medical conditions. Subsequently, they searched results for further conditions that may not have been noted by the provider at the time of the evaluation. To distinguish new or unstable conditions from stable existing disease, physician investigators reviewed previous chart records of patients.
Details of medical issues identified were categorized by the organ system involved: cardiovascular, pulmonary, hematology/oncology, neurology, gastroenterology, dermatology, renal, and endocrine. Specific abnormalities examined by system included: (1) Cardiovascular: hypertension (control as per American Heart Association guidelines),11 arrhythmia, bradycardia (heart rate less than 60 beats/min), and tachycardia (heart rate more than 100 beats/min); electrocardiographic abnormalities (atrioventricular block, fascicular or bundle branch block, arrhythmia, QT interval prolongation, ST segment abnormalities, T-wave abnormalities, presence of new Q waves). (2) Pulmonary: abnormal lung sounds, tachypnea (breathing more than 20 times per minute), hypopnea (breathing less than eight times per minute), chest radiograph abnormalities (new infiltrates or effusions, changes in cardiac or mediastinal contours), and increased Sleep Apnea Clinical Score (see next paragraph). (3) Hematology/oncology: anemia (hemoglobin less than 12.0 gm/dl for women or 13.5 gm/dl for men, drop from previous hemoglobin by 0.5 gm/dl or more), leukopenia (white blood cells less than 3500), leukocytosis (white blood cells more than 10,500/mcL), thrombocytopenia (platelets less than 150,000/mcL), and thrombocytosis (platelets more than 450,000/mcL). (4) Neurology: new or worsening chronic neurologic deficits on physical examination. (5) Gastroenterology: new or worsening chronic gastroenterologic symptoms. (6) Dermatology: new or worsening chronic dermatologic symptoms. (7) Renal: acute kidney injury (as defined by American Society of Nephrology guidelines)12 and electrolyte disturbances (hyponatremia [less than 135 mm], hypernatremia [more than 145 mm], hypokalemia [less than 3.5 mm], hyperkalemia [more than 5.1 mm]). (8) Endocrine: hyperglycemia as per American Diabetes Association guidelines13 (fasting glucose greater than 100 mg/dl [impaired fasting glucose] or 125 mg/dl [diabetes mellitus if second or greater frequency of this measurement]).
A Sleep Apnea Clinical Score (Flemons criteria) was based on historical features of snoring, apnea, hypertension, and neck circumference. This system was developed by Flemons et al.14 to identify outpatients with sleep apnea and has been validated. Subsequent investigations have also shown high sensitivity to detect patients at risk for perioperative sleep apnea.15,16 Patients at Mayo Clinic are routinely assessed for risk of sleep apnea during ophthalmic preanesthesia medical examination, and this score is calculated to estimate risk.15 If this number is greater than or equal to 15, patients are recommended to be referred to Sleep Medicine for further evaluation.
We recorded whether surgery was delayed, if there were any adverse events at time of surgery, or if there were any adverse events for up to 1 month after surgery. Adverse events were defined as hypertension, hypotension, arrhythmia, stroke, hypoxemia, symptomatic hypoglycemia, symptomatic hyperglycemia, death, cardiac arrest, myocardial infarction, respiratory failure, respiratory distress, congestive heart failure, and other new or unstable medical conditions developing at time of surgery. These definitions of adverse event conditions are identical to those of Schein etal.4 (table1, definition of adverse events). Adverse events were determined by review of ophthalmology follow-up visit notes at 1, 7, and 30 days postoperatively.
The primary aim of the study was to estimate the proportion of patients for whom new or unstable medical conditions were identified during their preanesthesia medical examination before ophthalmic surgery. To address these concerns, we conducted a preliminary study, whereby we reviewed records of 50 patients from 2007, who had ophthalmic surgery at Mayo Clinic in Jacksonville, Florida.17 Nineteen (38%) patients had new or unstable medical conditions noted on preanesthesia medical examination. Fifteen of these abnormal findings were from tests and nine from examination. Moreover, 7 of 19 abnormalities were not identified or acknowledged by the ophthalmic preanesthesia medical examination provider.
It was determined a priori that a sample size of at least 400 patients would be needed to estimate the percentage with a 95% CI width of at most 10%. The final sample size was larger than this, allowing for greater precision in estimation. Data were primarily categorical and were summarized in tables with number (%), along with 95% exact binomial CIs for key estimated proportions. All statistical analysis was performed using SAS (version 9.2; SAS Institute, Inc., Cary, NC) and R Statistical Software (version 2.14.0; R Foundation for Statistical Computing, Vienna, Austria).
A total of 575 patients were offered enrollment in our study, and 573 of these consented to participate (fig. 1). A further 43 patients either did not schedule surgery or later declined surgery and were not included in this study. The remaining 530 patients were included in the study, and all had a preoperative medical evaluation, had surgery, and were seen for their 1-, 7-, and 30-day postoperative follow-ups by their ophthalmologist. The window for the 7-day visit was 5–11 days, and the window for the 30-day visit was from 26 to 40 days. Although many patients had more than one surgery (e.g., in each eye), we report only results pertinent to the first eligible surgery per patient during the study period.
Baseline characteristics of the study participants are listed in table 1. The 530 ophthalmic preanesthesia medical examinations were performed by 71 different providers across various disciplines, categorized here as Family Practitioners, Internists, Anesthesiologists, and Advanced Registered Nurse Practitioners. The majority of patients studied were having cataract surgery (66%); the next most frequent surgery was oculoplastic (17%), and the remaining were retinal (5%), glaucoma (2%), and others (9%).
The study investigators examined the findings from the ophthalmic preanesthesia medical examinations to identify patients with new medical issues or unstable existing conditions that in their opinion were revealed by the preanesthesia medical examination and should have been noted by the original examination provider. Of the 530 patients, 214 (40%; 95% CI, 36–45%) were identified to have such issues or conditions. This group included 100 that were found by the providers and an additional 114 patients identified retrospectively by the study investigators. New medical issues were found in 117 patients (22%; 95% CI, 19–26%); unstable existing medical conditions were found in 122 patients (23%; 95% CI, 20–27%). Table 2 summarizes these findings. Approximately half of the overall findings were cardiovascular. Interestingly, 16% of patients were found by the study investigators to have new or unstable existing cardiovascular conditions that were not identified by preanesthesia medical examination provider.
Newly identified cardiovascular conditions included uncontrolled blood pressure (as a new diagnosis [n = 14]), new electrocardiographic abnormalities (such as first-degree atrioventricular block (n = 4), Wenckebach, Q waves, atrial fibrillation, inferior myocardial infarction with T-wave changes, anterior infarct, frequent premature ventricular contractions, marked sinus bradycardia with first-degree atrioventricular block, QT prolongation, ectopic atrial rhythm, QRS widening with T-wave inversion, nonspecific ST and T wave changes), orthostatic hypotension, exertional chest pain, hyperlipidemia, history of syncope and seizures with phlebotomy, irregular cardiac rhythm, and palpitations. Unstable cardiovascular conditions were uncontrolled hypertension (American Heart Association Stage 1 and 2, [n = 61])11 and bradycardia (n = 4). In most cases, uncontrolled hypertension noted at preanesthesia medical examination persisted on subsequent anesthetic records and future clinic visits.
The principal endocrine condition found by ophthalmic preanesthesia medical examination was hyperglycemia, with fasting glucose readings between 100 and 125 mg/dl. These were new diagnoses of impaired fasting glucose in 12 cases. Other hyperglycemic measurements indicated two cases of new onset of type 2 diabetes mellitus, with fasting glucose greater than 125 mg/dl13 and review of their chart records showing at least one previous fasting measurement in this range. These findings were in patients without previous diagnosis of diabetes mellitus.
Pulmonary diagnoses included new pulmonary infiltrates seen on chest radiograph (n = 3) and increased Sleep Apnea Clinical Score. Patients were referred for postoperative evaluation for sleep apnea if their score was increased (n= 8). Patients were also detected to be noncompliant with continuous positive airway pressure therapy by preanesthesia medical examination and directed back to Sleep Medicine for resumption of treatment after surgery (n = 3).
Ophthalmic preanesthesia medical examination detected renal abnormalities, which were primarily electrolyte imbalances based on laboratory test results (n = 9). Hyperkalemia and hypokalemia, and hyponatremia, were noted, in addition to development of chronic kidney disease stage 3 (n = 2), acute kidney injury, abnormal urinalysis (2+ proteinuria and 1+ urobilinogen), and urinary tract infection.
Overall, new and unstable medical conditions were identified by detailed review of ophthalmic preanesthesia medical examination results in 40% (214 of 530) of patients, around twice as noted by providers at the time of the evaluation (19%, 100 of 530). Detection rates were estimated to be highest in Internists (24%, 40 of 167) and Family Practitioners (20%, 29 of 146), with lower rates estimated in patients seen by Nurse Practitioners (16%, 26 of 161) and by Anesthesiologists (9%, 5 of 56). However, numbers of patients seen by each provider type, particularly anesthesiologists, were too small to make formal comparisons (table 3).
Impact of Preanesthesia Medical Examination Findings on Surgery Date
Of the 100 patients with abnormal conditions identified at ophthalmic preanesthesia medical examination, 12 (12%) had surgery delayed. Of the full 214 patients identified with new medical issues or unstable existing conditions, 13 (6%) had surgery delayed. Overall, surgery was delayed in 19 (4%) of the 530 patients.
Adverse Events during and after Surgery
A total of 49 (9%; 95% CI, 9–14%) of the 530 patients experienced adverse events, with 17 (3%) having events at or during surgery and 36 (7%) having events up to 1 month after surgery. These included both medical and ophthalmic issues. Four patients had events both during and in the first month after surgery; in all four cases, the events were unrelated to each other. Medical issues occurred in eight patients (2%), and ophthalmic issues occurred in 43 (8%; table 4).
Medical issues occurred at or during surgery in five patients (1%) and included chest pain, intraoperative atrial fibrillation, uncontrolled hyperglycemia, skin tear caused by intravenous catheter removal, and postoperative panic attacks, requiring overnight observation. Ophthalmic issues at or during surgery occurred in 12 patients (2%) and included floppy iris syndrome (n = 5), zonular laxity requiring vitrectomy (n = 2), subluxation of lens, zonular weakness, lost lens fragments, unable to reposition or remove subluxed posterior chamber intraocular lens (left and put in anterior chamber intraocular lens instead), and Descemets detachment.
Medical issues were identified in three patients (1%) at the 1-month postoperative visit and included hypertension (blood pressure 160/90 mmHg), history of fall, and syncope. Ophthalmic issues were identified in 33 patients (6%) at the 1-month postoperative visit and included intraocular pressure spike requiring further procedures (n = 3), lens subluxation/dislocation (n = 3), vitreous hemorrhage (n = 2), surgical site infections(n = 2), vitreous detachment (n = 2), epitheliopathy (n = 2), lid infection, lid under correction, choroidal effusions, keratitis from postoperative eye drops, horizontal diplopia, failure of scleral buckle to reattach retina, upper visual field defect, retinal hemorrhage, opening of macular hole, eye pain requiring emergency department evaluation, blurred vision, corneal abrasion, nonviable graft requiring reoperation, wound dehiscence, wet age-related macular degeneration, triesence for macular edema, hypotonia, lost lens fragments, and graft displacement. There was no suggestion that complications were any more frequent in those patients with medical issues or abnormal conditions identified at their preoperative examination.
The primary finding of our prospective study of ophthalmic preanesthesia medical examination was the frequent discovery of new or unstable medical conditions. Although the intended goal and basis for preanesthesia medical examination has been to minimize surgical risk, it involves a review of the general health of the patient. This type of review exposes a variety of medical issues, which may have long-term importance.
Our data indicate that ophthalmic preanesthesia medical examination reveals new and unstable conditions, such as hypertension, diabetes mellitus, and sleep apnea, which have been recognized as significant contributors to cardiovascular disease.18,19 It has been estimated that for every 10% improvement in hypertension treatment, 14,000 lives may be saved and only 46% of patients with hypertension currently have adequate blood pressure control.20,21 Thus, the discovery of these conditions not only has personal clinical implications for the patient but also yields a significant public health impact.
The United States is currently experiencing an epidemic of obesity, with concomitant increase in related diseases of diabetes mellitus and obstructive sleep apnea.22,23 An additional 8 million cases of diabetes are expected to develop in the United States, secondary to obesity, by 2030.22 The current prevalence of obesity (defined as body mass index >30) is 33.7%.19 Our study further illustrates this ongoing development of hyperglycemia among patients, and obesity, measured by Sleep Apnea Clinical Score. The significance of these findings discovered at ophthalmic preanesthesia medical examination and their impact on health outcomes warrants further investigation.
Some providers did not acknowledge abnormalities found during the ophthalmic preanesthesia medical examination process, both findings from physical examination and testing. Medical issues were less often recognized by anesthesiologists than other provider types; however, this may be due to sampling variability, associated with the smaller number of patients evaluated by this group. If the difference is real, then this could be due to differential training of anesthesiologists. It is also entirely possible that the preanesthesia medical examination goals are to document only those findings considered to be relevant to immediate surgical risk.
In our review of the published ophthalmic anesthesia literature, we used PubMed with terms “ophthalmology PAME” (Preanesthesia Medical Examination), “ophthalmology preanesthesia medical examination,” and “ophthalmology preoperative examination.” The frequency of new and unstable medical findings from ophthalmic preanesthesia medical examination noted in our study has not been previously described. Previous studies have described the prevalence of preexisting disease noted on ophthalmic preanesthesia medical examination. However, they have not detailed whether ophthalmic preanesthesia medical examination detects new and unstable medical findings, as we have.7–9 Moreover, these studies did not address the relevance of abnormal test findings to the long-term health care of the patient, only to their immediate anesthetic ramifications.10 Acknowledgment of abnormal findings, even when not directly related to surgical risk, is a crucial step toward referral of patients for postoperative evaluation.
With respect to perioperative and postoperative outcomes, findings from our study are consistent with the conclusions of previous investigators, that preanesthesia medical examination does not commonly alter conduct of ophthalmic surgery or affect immediate postsurgical outcomes.4,5 Similarly, testing performed for preanesthesia medical examination was not associated with surgical results.4,5,9,23 Few surgeries were cancelled or delayed by preanesthesia medical examination findings, even when new or unstable medical conditions were noted by providers.
Limitations of this study include its conduct at a single institution, which is a tertiary referral center, which may have altered patient sample. Patients were mostly elderly, which could influence the frequency of certain disease states. Moreover, the length of postoperative follow-up was not sufficient to allow for development of complications from many of the findings at ophthalmic preanesthesia medical examination such as uncontrolled hypertension. Ophthalmologists provided follow-up at 1, 7, and 30 days after surgery, as per usual clinical care, and it is possible that they may have missed some nonophthalmic problems that developed postoperatively. This study only examined ophthalmic surgical patients, who may represent a unique group relative to patients having other types of surgery. Future research in this field is needed to address the frequency of these findings in other patient populations and to develop methods for routine communication of preanesthesia medical examination abnormalities to primary care physicians.
The American College of Cardiology/American Heart Association 2009 Updated Guidelines for Perioperative Cardiovascular Evaluation state, “…it is important that the care team responsible for the long-term care of the patient be provided with complete information about any cardiovascular abnormalities or risk factors for [Coronary Artery Disease] identified during the perioperative period.”24 Clearly, ophthalmic preanesthesia medical examination is not a substitute for routine primary medical care. However, if patients are found to have abnormalities during the preanesthesia medical examination process, either on history and physical examination or on testing, these results should be recognized and conveyed to the primary care physician for postoperative follow-up, even if the findings are not relevant to the conduct of the ophthalmic surgery. In other words, preoperative evaluation has potential value well beyond the immediate perioperative period.
Many years may pass before the negative health outcomes of preanesthesia medical examination–revealed conditions seen in our study are manifest. We believe that the goal of ophthalmic preanesthesia medical examination must include careful review of the data collected, because of its relevance to all aspects of patient health, not only those immediately salient to conduct of surgery. Ophthalmic preanesthesia medical examination findings may have significant global health implications for patients and suggest the need for modification of provider behaviors. In other words, preoperative evaluation has potential value well beyond the immediate perioperative period.
The authors are very thankful for the assistance of Shannon L. Kennedy, B.A., Certified Clinical Research Coordinator, Clinical Studies Unit, with study enrollment and data entry; Melissa D. Efird, C.O.T., Ophthalmic Technician II, Department of Ophthalmology, and Kathy E. Jung, C.O.A., Ophthalmic Technician II, Department of Ophthalmology, with study enrollment; Alison M. Dowdell, B.A., Academic and Research Support Specialist, Department of Academic and Research Support, with manuscript formatting; and Kelly E. Viola, B.S., Department Lead, Department of Academic and Research Support, with figure illustration. All of these persons are salaried employees of Mayo Clinic, Jacksonville, Florida, and received no additional compensation for their work on this study.