Postoperative opioid-induced respiratory depression or oversedation requiring naloxone treatment in a community hospital: a case series.

Background: Postoperative opioid-induced respiratory depression and oversedation can lead to fatal events and increase perioperative mortality. In reports from major academic centers, naloxone administration has been used as a proxy for severe opioid overdose. Herein, we studied the incidence, clinical characteristics, and outcomes of postoperative naloxone use in a mid-size community hospital. Methods: This was a retrospective review of adult patients who received naloxone within 48 postoperative hours between July 9, 2017, and May 31, 2022. Results: During the study timeframe, a total of 23,362 surgical procedures were performed and a total of 19 patients received naloxone (8 in the recovery room, 11 on hospital wards), with an incidence of 8.1 [95% confidence interval 4.9-12.7] per 10,000 anesthetics. In 12 cases (63%), naloxone was indicated for oversedation, and in 7 cases (37%), for opioid-induced respiratory depression. All patients received naloxone within the first 24 postoperative hours. While all patients survived the opioid-related adverse event, 2 patients were intubated, 1 developed stress-induced cardiomyopathy, and 5 required intensive care unit admission. Conclusion: The rate of early postoperative opioid-induced respiratory depression or oversedation in our community hospital was low; however, these patients often require a substantial escalation of medical management.

Life-Threatening Aortic Dissection during Pregnancy: A Case Report of Undiagnosed FBN1-Related Marfan Syndrome at 39 Weeks Gestation.

BACKGROUND Inherited deficiencies in the FBN1 gene, which encodes fibrillin-1, result in Marfan syndrome, an autosomal dominant connective tissue disorder that is associated with aortic root dilatation and predisposes to aortic dissection. This report is of a 37-year-old woman presenting at 39 weeks of pregnancy with acute thoracic aortic dissection due to previously undiagnosed FBN1-related Marfan syndrome. This case report aims to illustrate the challenges in the diagnosis and in the peri-operative management of acute aortic dissection during pregnancy. CASE REPORT A healthy 37-year-old woman at 39 weeks of gestation presented to our hospital with dyspnea and chest pain. Initial evaluation for pulmonary embolism with chest computed tomography was unrevealing. The patient was admitted to the intensive care unit for further management. Overnight, her clinical conditions deteriorated, and a transthoracic echocardiography was obtained, demonstrating an acute ascending aortic dissection. She emergently underwent a successful combined cesarean section and ascending aortic dissection repair, with no immediate complications. On postoperative day 4 she developed cardiac tamponade, for which she underwent emergent mediastinal exploration. She was discharged home on postoperative day 10. A month later she completed genetic testing, which revealed a pathogenic mutation in the FBN1 gene, consistent with a molecular diagnosis of Marfan syndrome. CONCLUSIONS This report has shown that FBN1-related Marfan's syndrome has a variable clinical presentation that can include life-threatening aortic dissection during pregnancy. Successful diagnosis and management of these patients is challenging and requires multidisciplinary expertise, including confirmation of the diagnosis by a clinical geneticist.

Peripartum anesthetic management in patients with Ebstein anomaly: a case series.

Ebstein anomaly is a rare congenital cardiac condition associated with displacement and incompetence of the tricuspid valve. Peripartum anesthetic management can be particularly challenging since these patients are at high risk of cardiac failure and tachyarrhythmias. Risk stratification is important since it helps to identify high-risk patients who should deliver at a tertiary care center where a multidisciplinary team (obstetrics, cardiology, anesthesiology, and neonatology) is immediately available. We describe the peripartum anesthetic management of 9 patients with Ebstein anomaly who underwent 12 deliveries at our institution. All patients tolerated neuraxial anesthesia and analgesia well. No maternal or fetal deaths occurred.

A midline retroperitoneal approach for complex abdominal aortic repair: Case description and operative technique.

In the current endovascular era, open repair of complex aortic aneurysms is becoming a rare, but indispensable, part of vascular surgeons' skill set in specific scenarios. For young, low-risk patients and patients with connective tissue disorders, early target vessel bifurcation, a horseshoe kidney, or pedunculated intraluminal aortic thrombus, fenestrated-branched stent graft technology will not be applicable without significant risks. Thus, an open surgical approach has been recommended for these patients. Most vascular surgeons will be familiar with a transperitoneal approach or a retroperitoneal approach with a lateral incision. For patients with a horseshoe kidney, an inflammatory aneurysm, or a history of multiple intraperitoneal procedures, a retroperitoneal approach should be preferred. In the present report, we have described in detail the optimization of a retroperitoneal approach through a midline incision that provides excellent exposure to the paravisceral aorta, improves exposure to the right renal artery and right iliac artery bifurcation (which is limited using the left flank retroperitoneal approach), and avoids division of the lateral abdominal wall muscles, which has often been associated with iatrogenic muscle denervation and postoperative bulging for four patients who had required complex aortic reconstruction.

Spinal Anesthesia for Amyotrophic Lateral Sclerosis Patient Undergoing Lower Extremity Orthopedic Surgery: An Overview of the Anesthetic Considerations.

BACKGROUND: Amyotrophic lateral sclerosis is a progressive neurodegenerative disease primarily affecting the upper and lower motor neurons. Patients present with a variety of clinical manifestations inevitably resulting in death secondary to respiratory insufficiency from muscle weakness and consequential pulmonary complications. Despite the lack of universal consensus on the ideal anesthetic approach to amyotrophic lateral sclerosis patients undergoing lower extremity total joint surgery, there are few noteworthy anesthetic considerations in this cohort. CASE REPORT: A 75-year-old male with multiple medical comorbidities, including a recent diagnosis of amyotrophic lateral sclerosis, presented to a large academic medical center for a right total hip arthroplasty revision. The patient's preoperative neurologic examination demonstrated brisk deep tendon reflexes, visible fasciculations of lower extremities, and motor weakness of upper and lower extremities. Serology demonstrated an elevated creatine kinase, and an electromyography study showed active denervation in the cervical, thoracic, and lumbosacral regions. After a careful risk-benefit analysis was performed, involving a multidisciplinary team approach, the patient successfully underwent the surgical procedure with a spinal anesthetic and minimal sedation. Perioperative course was unremarkable, and there were no neurologic complications in the first 6 months after surgery. CONCLUSION: Patients with amyotrophic lateral sclerosis present unique challenges for anesthesia providers. General anesthesia may potentially worsen respiratory function; therefore, alternative methods to avoiding airway manipulation should be considered. Conversely, regional techniques may carry the risk of exacerbating pre-existing neurologic symptoms. Currently, no definite guidelines exist on the perioperative anesthetic management of amyotrophic lateral sclerosis patients; ultimately, the decision to perform regional anesthesia should be based on analyzing a patient's risk against the potential benefits.

Intraoperative Fluid Balance and Perioperative Outcomes After Aortic Valve Surgery.

BACKGROUND: The effect of intraoperative fluid balance on postoperative acute kidney injury (AKI) in cardiac surgical patients is poorly defined. METHODS: In this retrospective study of patients undergoing aortic valve replacement for aortic stenosis, the primary outcome of interest was postoperative AKI. Secondary outcomes were postoperative fluid balance, cardiac index, vasopressor use, hospital-free days, stroke, myocardial infarction, hospital readmission, and 30- and 90-day mortality. RESULTS: A total of 2327 patients were analyzed. Positive intraoperative fluid balance was associated with lower odds of AKI; the lowest odds were in the 20- to 39-mL/kg group (odds ratio, 0.56; 95% confidence interval, 0.38-0.81; P = .002). Positive intraoperative fluid balance was associated with a lower postoperative fluid balance. Increased ultrafiltration volume was associated with increased postoperative fluid resuscitation and vasopressor use. AKI was associated with increased 30- and 90-day mortality. Increased fluid balance was associated with increased odds of myocardial infarction and 30-day mortality. Increased ultrafiltration volume was associated with increased odds of 30- and 90-day mortality. CONCLUSIONS: In patients who underwent aortic valve replacement for aortic stenosis, positive intraoperative fluid balance was associated with decreased odds of AKI. Patients developing AKI had increased 30- and 90-day mortality. Although the overall incidence was low, increased intraoperative fluid balance was associated with myocardial infarction and 30-day mortality, whereas increased ultrafiltration volume was associated with 30- and 90-day morality. Prospective studies are needed to better define proper intraoperative fluid management in patients undergoing cardiac surgery.

Intraoperative methadone administration and postoperative pain control: a systematic review and meta-analysis.

Postoperative pain is not adequately managed in greater than 40% of surgical patients and is a high priority for perioperative research. In this meta-analysis, we examined studies comparing postoperative opioid consumption and pain scores in surgical patients who received methadone by any route vs those who received another opioid by any route. Studies were identified from PubMed, Cochrane, Web of Science, EMBASE, and Scopus from January 1966 to November 2018. Pooled odds ratios were calculated for a primary outcome of postoperative opioid consumption and secondary outcomes of time-to-extubation, time-to-first postoperative analgesia request, satisfaction, hospital length-of-stay, and complications. Postoperative pain scores were assessed qualitatively. Ten studies (617 patients) were included. Postoperative opioid consumption at 24 hours was lower in the methadone group vs control (mean difference = -15.22 mg oral morphine equivalents, 95% confidence interval -27.05 to -3.38; P = 0.01). Patients in the methadone group generally reported lower postoperative pain scores in 7 of 10 studies. Meta-analysis revealed greater satisfaction scores with analgesia in the methadone group vs control (0-100 visual analog scale; mean difference = 7.16, 95% confidence interval 2.30-12.01; P = 0.004). There was no difference in time-to-extubation, time-to-first analgesia request, hospital length-of-stay, or complications (nausea, sedation, respiratory depression, and hypoxemia). The results demonstrate that surgical patients who received intraoperative methadone had lower postoperative opioid consumption, generally reported lower pain scores and experienced better satisfaction with analgesia. However, these advantages need to be weighed carefully against dangerous risks with perioperative methadone, specifically respiratory depression and arrhythmia. Future studies should explore logistics, safety, and cost effectiveness.

Essential Thrombocythemia and Cardiac Surgery: A Case Series and Review of the Literature.

BACKGROUND: Essential thrombocythemia (ET) is a rare myeloproliferative disorder characterized by an unexplained thrombocytosis (>450 × 109/L) and associated vasomotor, thrombotic, and hemorrhagic manifestations. Although the literature detailing the perioperative management of patients with ET undergoing cardiac operations is sparse, major perioperative complications have been reported, particularly in poorly controlled patients presenting with platelet counts of 800 × 109/L or higher. The purpose of this study was to provide the experience at a large tertiary medical center in managing patients with ET undergoing cardiac operation and to summarize the available literature. METHODS: Patients with ET undergoing cardiac operations between January 1, 2006, and May 1, 2016, were identified. Perioperative data were exhaustively reviewed and recorded. An extensive literature search for "essential thrombocythemia" and "cardiac surgery" was performed. RESULTS: During the study period, 25 patients with ET underwent cardiac operations, and 24 had immediate preoperative platelet counts of less than 800 × 109/L. Perioperative complications related to ET occurred in 1 of 25 patients (4%). The immediate preoperative platelet count was 181 × 109/L. A literature search identified 18 patients who underwent cardiac operations, with major perioperative complications occurring in 5 (28%), of which 4 of 5 had an immediate preoperative platelet count of 800 × 109/L or higher. CONCLUSIONS: Patients with ET undergoing cardiac operations represent a complex cohort at risk for perioperative thrombotic or hemorrhagic complications, or both. Although not currently an indication for platelet reduction therapy by risk stratification criteria, preoperative cytoreduction to platelet counts of less than 800 × 109/L and perhaps lower should be considered in patients undergoing cardiac operations.

Resection of Intrathoracic Paraganglioma With and Without Cardiopulmonary Bypass.

BACKGROUND: Intrathoracic paragangliomas (PGLs) are rare tumors. Approximately 50% originate from and around cardiac structures. METHODS: A retrospective review was made of the perioperative course of patients with intrathoracic PGL resection from 2000 through 2015 at Mayo Clinic in Rochester, Minnesota. RESULTS: Twenty-two patients underwent PGL resection. Sixteen patients (73%) had functioning tumors (11, noradrenergic; 4, mixed noradrenergic and dopaminergic; 1, dopaminergic). Patients with functioning tumors received preoperative adrenergic blockade: 15 (68%), α1,2-adrenergic receptor antagonist; 4 (18%), α1-adrenergic receptor antagonists; and 13 (59%) metyrosine. Six patients with nonfunctioning tumors had no adrenergic blockade. Twelve patients had tumor resection without cardiopulmonary bypass-9 for PGL associated with the great vessels, 2 for PGL with pericardial involvement, and 1 for PGL in right atrioventricular groove. Ten patients required cardiopulmonary bypass; for 9, the tumor involved cardiac structures and for 1, it involved ascending aorta and proximal aortic arch. Of these, 1 patient had uncontrollable bleeding and died intraoperatively. Other than this single death, there were no inhospital major cardiac or pulmonary complications. Median follow-up was 8.2 years (range, 2.1 to 17.2). Six patients subsequently had metastatic disease, and of them, 1 died 6 years after the operation. CONCLUSIONS: In this series, 73% of intrathoracic PGLs were functional and involved noradrenergic, mixed noradrenergic and dopaminergic, or pure dopaminergic secretion. Cardiac and pericardial paraganglioma resection may require cardiopulmonary bypass. Although intraoperative bleeding in most complex cases may be uncontrollable, as for 1 of our patients, those who survived hospital discharge had favorable long-term outcomes.

Isoflurane and postoperative respiratory depression following laparoscopic surgery: A retrospective propensity-matched analysis.

Episodes of respiratory depression during the immediate postoperative recovery period (Phase I post-anesthesia recovery) have been associated with respiratory complications during Phase II recovery. Using multivariable analyses in several surgical cohorts, we previously identified potential associations between patient and perioperative factors and increased risk for Phase I respiratory depression. The aim of this study is to use the propensity-matched analysis to specifically assess for a potential association between the use of isoflurane and episodes of Phase I respiratory depression after laparoscopic operations. The electronic medical records of 8567 patients who underwent laparoscopic operations between January 1, 2010 and July 31, 2014, lasting ≥90 minutes, were retrospectively analyzed. Propensity-matched patients anesthetized without isoflurane were identified for 3403 patients anesthetized with isoflurane. Compared to the use of desflurane, sevoflurane or propofol infusion, maintenance of anesthesia with isoflurane was associated with an increased likelihood of Phase I respiratory depression (OR 95% CI, 1.32, 1.15-1.50, p < 0.001) and longer Phase I recovery (126 vs. 110 minutes, p < 0.001). The use of isoflurane was associated with increased rates of postoperative respiratory depression and postoperative recovery when compared to sevoflurane, desflurane, or propofol infusion.

Patients with glycogen storage diseases undergoing anesthesia: a case series.

BACKGROUND: Glycogen storage diseases are rare genetic disorders of glycogen synthesis, degradation, or metabolism regulation. When these patients are subjected to anesthesia, perioperative complications can develop, including hypoglycemia, rhabdomyolysis, myoglobinuria, acute renal failure, and postoperative fatigue. The objective of this study was to describe the perioperative course of a cohort of patients with glycogen storage diseases. METHODS: This is a retrospective review of patients with glycogen storage diseases undergoing anesthetic care at our institution from January 1, 1990, through June 30, 2015 to assess perioperative management and outcomes. RESULTS: We identified 30 patients with a glycogen storage disease who underwent 41 procedures under anesthesia management. Intraoperative lactic acidosis developed during 4 major surgeries (3 liver transplants, 1 myectomy), and in all cases resolved within 24 postoperative hours. Lactated Ringer solution was used frequently. Preoperative and intraoperative hypoglycemia was noted in some patients with glycogen storage disease type I, all of which responded to administration of dextrose-containing solutions. No serious postoperative complications occurred. CONCLUSIONS: Patients with glycogen storage disease, despite substantial comorbid conditions, tolerates the anesthetic management without major complications. Several patients who experienced self-limited metabolic acidosis were undergoing major surgical procedures, during which acidosis could be anticipated. Close monitoring and management of blood glucose levels of patients with glycogen storage disease type I is prudent.

History of carotid surgery: from ancient greeks to the modern era.

A relationship between decreased carotid arterial flow and apoplectic manifestations was already suspected by the ancient Greeks. Early attempts at carotid surgery, however, were limited to emergency arterial ligation in patients with neck trauma. Attempts to suture arterial stumps together to restore blood flow paved the way for Carrel's revolutionary idea of reconstructing the resected or injured arterial segment with an interposition vein graft. DeBakey and Eastcott were the first to perform carotid endarterectomy in North America and the United Kingdom, respectively. In 1959, DeBakey proposed a cooperative study to assess the effectiveness of carotid endarterectomy in the treatment and prevention of ischemic cerebrovascular disease. The study was officially designated the Joint Study of Extracranial Arterial Occlusion and represented the first trial in the United States in which large numbers of patients were randomly allocated to surgical or nonsurgical therapy.

Anesthesia and incident dementia: a population-based, nested, case-control study.

OBJECTIVE: To test the hypothesis that exposure to procedures requiring general anesthesia during adulthood is not significantly associated with incident dementia using a retrospective, population-based, nested, case-control study design. PARTICIPANTS AND METHODS: Using the Rochester Epidemiology Project and the Mayo Clinic Alzheimer's Disease Patient Registry, residents of Olmsted County, Minnesota, diagnosed as having dementia between January 1, 1985, and December 31, 1994, were identified. For each incident case, a sex- and age-matched control was randomly selected from the general pool of Olmsted County residents who were dementia free in the index year of dementia diagnosis. Medical records were reviewed to determine exposures to procedures requiring anesthesia after age 45 years and before the index year. Data were analyzed using logistic regression. RESULTS: We analyzed 877 cases of dementia, each with a corresponding control. Of the dementia cases, 615 (70%) underwent 1681 procedures requiring general anesthesia; of the controls, 636 (73%) underwent 1638 procedures. When assessed as a dichotomous variable, anesthetic exposure was not significantly associated with dementia (odds ratio, 0.89; 95% CI, 0.73-1.10; P=.27). In addition, no significant association was found when exposure was quantified as number of procedures (odds ratios, 0.87, 0.86, and 1.0 for 1, 2-3, and ≥4 exposures, respectively, compared with none; P=.51). CONCLUSION: This study found no significant association between exposure to procedures requiring general anesthesia after age 45 years and incident dementia.

Acute kidney injury following bariatric surgery.

BACKGROUND: Postoperative acute kidney injury (AKI) following bariatric surgery has not been well studied. The aim of this study is to identify factors associated with risk of AKI. METHODS: The medical records of adult patients who underwent bariatric surgery between March 1, 2005 and March 31, 2011 at the Mayo Clinic were reviewed to identify patients who experienced AKI, defined as postoperative increase in serum creatinine (sCr) by 0.3 mg/dL within 72 h. For each AKI case, two controls were matched for surgical approach (laparotomy vs. laparoscopic). A chart review was conducted and conditional logistic regression analyses were performed to identify risk factors for AKI. RESULTS: There were 1,227 patients who underwent bariatric surgery, and of these, 71 developed AKI (5.8 %). The median sCr increase was 0.4 (interquartile range 0.3-0.6) mg/dL. Independent patient factors associated with increased risk included higher body mass index [odds ratio (OR) 1.24, 95 % CI 1.06-1.46 per 5 unit increase, P = 0.01] and medically treated diabetes mellitus (OR 2.77, 1.36-5.65, P = 0.01). Patients experiencing AKI had higher rates of blood transfusions (P < 0.01), postsurgical complications (P < 0.01), and longer hospital stays (P < 0.01). Another 30 patients developed kidney injury after 72 postoperative hours, usually in the setting of dehydration. CONCLUSIONS: Kidney injury following bariatric surgery is not uncommon and is associated with higher body mass index and diabetes. Further, there should be a high risk of suspicion for kidney injury in postoperative patients developing volume depletion.

Acute kidney injury following total joint arthroplasty: retrospective analysis.

INTRODUCTION: Postoperative acute kidney injury (AKI) following arthroplasty has not been well studied. Our aim was to identify factors associated with increased risk of AKI. METHODS: The medical records for adult patients who underwent elective total joint arthroplasty during June 1, 2007 to May 31, 2010 at the Mayo Clinic were reviewed to identify patients with normal preoperative kidney function who experienced perioperative AKI, defined as an increase in serum creatinine (sCr) by 26.4 µmol·L(-1). For each AKI case, two controls were identified and matched for age, sex, and type of operation. Medical records were abstracted for demographics, comorbid conditions, and preoperative, intraoperative, and postoperative variables. Conditional logistic regression analyses were performed to identify risk factors for AKI. RESULTS: Of the 9,171 patients who underwent joint replacement operations, 167 with normal preoperative renal function developed AKI with a median [25(th), 75(th)] increase in sCr of 35.4 [26.4, 44.2] µmol·L(-1). No patient required dialysis. A higher than normal body mass index, diabetes mellitus, the number of baseline antihypertensive medications, cerebral or peripheral vascular disease, use of general anesthesia, and perioperative blood transfusions were independently associated with risk for AKI. Hospital length of stay and intensive care admissions were greater in AKI patients, and in 12.0% of patients, sCr remained at least 26.4 µmol·L(-1) higher than preoperative baseline at least three months after surgery. CONCLUSION: In this case-control investigation, we identified several factors associated with the development of postoperative AKI. Recognition of these risk factors could allow for the adoption of perioperative renal protective strategies in patients undergoing arthroplasty.

Kidney injury during pregnancy: associated comorbid conditions and outcomes.

PURPOSE: To investigate the characteristics of women who have kidney injury during pregnancy. METHODS: Medical records of all women who gave birth at our institution between January 1, 2005, and December 31, 2010, were retrospectively reviewed electronically. We identified those who incurred a kidney injury [defined by modified Acute Kidney Injury Network (AKIN) criteria: serum creatinine (sCr) increase ≥0.3 mg/dL] during pregnancy or within 30 days postpartum. Identified case records were reviewed in detail. RESULTS: During the study period, 54 women had a kidney injury (0.4 % estimated incidence) with a mean (SD) increase in sCr of 0.46 (0.29) mg/dL; most injuries were AKIN stage 1 with transient increases in sCr. Most of the women (n = 48, 87.3 %) had substantial preexisting or pregnancy-associated comorbid conditions (e.g., kidney disease, hypertension, diabetes), complications (e.g., preeclampsia, HELLP syndrome), or a complicated obstetric course (hemorrhage, infections) that could have contributed to the development of a kidney injury. Two patients had AKIN stage 3 injuries: a previously healthy patient who had a massive hemorrhage during cesarean delivery, and a patient with a renal transplant who had deterioration and eventual postpartum failure of her transplanted kidney. CONCLUSIONS: The majority of pregnancy-associated kidney injuries were transient and occurred in women with substantial comorbid conditions or complicated pregnancies.

Sirolimus in solid organ transplantation: current therapies and new frontiers.

Sirolimus (SRL) is a mammalian target of rapamycin inhibitor, which provides an immunosuppressive effect by inhibiting cell cycle progression. The encouraging results of combined SRL-cyclosporine therapy paved the way to further immunosuppressant combinations. Although SRL is relatively non-nephrotoxic when administered as monotherapy, it pharmacodynamically enhances the toxicity of calcineurin inhibitors. Other side effects may include hyperlipidemia and myelosuppression and less commonly wound healing impairment, proteinuria, edema and pneumonitis. Surprisingly, SRL also showed encouraging properties as an antiatherogenic and antineoplastic, opening a large spectrum of new potential applications. Whether SRL can be used safely over the long term with low doses of calcineurin inhibitors requires further study. The use of SRL as a corticosteroid-sparing agent also remains to be proven in controlled trials.

Allergic reactions during anesthesia at a large United States referral center.

BACKGROUND: The types of agents implicated to trigger intraoperative anaphylactic reactions vary among reports, and there are no recent series from the United States. In this retrospective study, we examined perioperative anaphylactic reactions that occurred at a major tertiary referral academic center. METHODS: To characterize perioperative allergens associated with anaphylactic reactions, we reviewed the Mayo Clinic Division of Allergic Diseases skin test database between 1992 to 2010. The records of all patients who were tested for perioperative and anesthetic medications were reviewed. Charts that included a detailed history obtained by an allergist, skin test results, and tryptase measurements when available were reviewed and categorized. RESULTS: Thirty-eight patients were found to have an anaphylactic reaction during anesthesia, of which 18 were immunoglobulin (Ig)E-mediated anaphylactic reactions (likely causative agent identified by skin test), 6 were non-IgE-mediated anaphylactic reactions (elevated tryptase levels and negative skin test), and 14 were probable non-IgE-mediated anaphylactic reactions (tryptase levels normal or not obtained and negative skin test). Of the IgE-mediated anaphylactic reactions, antibiotics were the most prevalent likely causative agent (50%) whereas neuromuscular blocking drugs were implicated as a likely causative agent in 11% of reactions. CONCLUSION: Antibiotics were the most common likely causative agent associated with IgE-mediated anaphylactic reactions; however, for 52.6% of reactions, a causative agent could not be determined, suggesting a non-IgE-mediated anaphylactic reaction. The undiagnosed allergic reactions place patients at risk of a subsequent reexposure to the same allergen, or lead to unnecessary avoidance of needed medications.