Search

The coronavirus disease 2019 (COVID-19) pandemic has revealed that even the best-resourced hospitals may lack sufficient ventilators to support patients under surge conditions. During a pandemic or mass trauma, an affordable, low-maintenance, off-the-shelf device that would allow health care teams to rapidly expand their ventilator capacity could prove lifesaving, but only if it can be safely integrated into a complex and rapidly changing clinical environment. Here, we define an approach to safe ventilator sharing that prioritizes predictable and independent care of patients sharing a ventilator. Subsequently, we detail the design and testing of a ventilator-splitting circuit that follows this approach and describe our clinical experience with this circuit during the COVID-19 pandemic. This circuit was able to provide individualized and titratable ventilatory support with individualized positive end-expiratory pressure (PEEP) to 2 critically ill patients at the same time, while insulating each patient from changes in the other's condition. We share insights from our experience using this technology in the intensive care unit and outline recommendations for future clinical applications.

As the population of the world is aging the number of geriatric patients undergoing liver transplantation (LT) is also increasing. They pose a unique challenge for the caregivers, as they have age-related physiological changes, multiple comorbidities and cirrhosis-related pathologies.Twenty-two percent of patients who undergo LT are older than 65 years. Many patients suffer from nonalcoholic steatohepatitis (NASH), hepatocellular carcinoma and hepatitis-C virus. Incidence of NASH tends to increase with age, obesity, diabetes and metabolic syndrome. Elderly patients require comprehensive cognitive, cardiac and pulmonary evaluation prior to LT. Cirrhotic cardiomyopathy, hepatopulmonary syndrome, portopulmonary hypertension and frailty are of specific concern.Proportion of elderly patients who are undergoing LT continues to increase. These patients require comprehensive cardiopulmonary and frailty evaluation. Consensus-based practice advisories need to be developed to standardize preoperative evaluation of geriatric patients awaiting LT.

The certainty that prehabilitation improves postoperative outcomes is not clear. The objective of this umbrella review (i.e. systematic review of systematic reviews) was to synthesise and evaluate evidence for prehabilitation in improving health, experience, or cost outcomes.We performed an umbrella review of prehabilitation systematic reviews. MEDLINE, Embase, Cochrane, Cumulative Index to Nursing and Allied Health Literature, PsycINFO, Joanna Briggs Institute's database, and Web of Science were searched (inception to October 20, 2020). We included all systematic reviews of elective, adult patients undergoing surgery and exposed to a prehabilitation intervention, where health, experience, or cost outcomes were reported. Evidence certainty was assessed using Grading of Recommendations Assessment, Development and Evaluation. Primary syntheses of any prehabilitation were stratified by surgery type.From 1412 titles, 55 systematic reviews were included. For patients with cancer undergoing surgery who participate in any prehabilitation, moderate certainty evidence supports improvements in functional recovery. Low to very low certainty evidence supports reductions in complications (mixed, cardiovascular, and cancer surgery), non-home discharge (orthopaedic surgery), and length of stay (mixed, cardiovascular, and cancer surgery). There was low to very low certainty evidence that exercise prehabilitation reduces the risk of complications, non-home discharge, and length of stay. There was low to very low certainty evidence that nutritional prehabilitation reduces risk of complications, mortality, and length of stay.Low certainty evidence suggests that prehabilitation may improve postoperative outcomes. Future low risk of bias, randomised trials, synthesised using recommended standards, are required to inform practice. Optimal patient selection, intervention design, and intervention duration must also be determined.

We aimed to study the association between propofol induction dose (mg/kg) and pre-incision severe hypotension (Mean Arterial Pressure (MAP) ≤ 55 mmHg) among patients ≥65 years of age.Retrospective Observational.40 centers participating in the Multicenter Perioperative Outcomes Group consortium.Patients ≥65 years of age undergoing non-cardiac, non-vascular surgery who received propofol for general anesthetic induction prior to endotracheal intubation between January 2014 and December 2018.None.The primary exposure was total propofol induction dose in mg/kg, and the primary outcome was occurrence of severe hypotension (MAP≤55 mmHg) prior to surgical incision, stratified by non-invasive vs. invasive blood pressure monitoring type.Among 320,585 total patients, 22.6% experienced the outcome of pre-incision severe hypotension (MAP≤55 mmHg). When stratified by blood pressure monitoring type, 20.7% with non-invasive blood pressure measurements, and 35.0% with invasive blood pressure measurements had the outcome. After controlling for a variety of patient and procedural factors, there was a significant independent association between propofol induction dose and pre-incision hypotension (Non-invasive blood pressure cohort odds ratio (OR) 1.10; 95% confidence interval (CI) 1.07 to 1.13; p 0.001; and Invasive blood pressure cohort OR 1.15; 95%CI 1.10 to 1.21; adjusted p 0.001). The association was robust to alternative definitions of the outcome, including less severe hypotension (MAP≤65 mmHg) and blood pressure drop from baseline as a continuous measure. Although no threshold safe induction dose was identified at which hypotension was avoided, an analysis of propofol dose greater or less than 1.5 mg/kg (i.e. the maximum FDA-defined typical induction dose) demonstrated that doses in excess of the FDAs threshold were positively associated with odds of severe hypotension (Non-invasive cohort: OR 1.05; 95% CI 1.02 to 1.08; p 0.001; Invasive cohort: OR 1.11; 95%CI 1.05 to 1.17; adjusted p 0.001).In a multicenter cohort of geriatric surgical patients receiving propofol for general anesthetic induction and endotracheal intubation, severe pre-incision hypotension (MAP ≤55 mmHg) that has previously been associated with postoperative morbidity was common. The dose of propofol used was significantly associated with increased odds of this outcome after controlling for a number of clinically relevant factors. Future studies that are designed to test different approaches to anesthesia induction for reducing severe post induction pre-incision hypotension are warranted.

Summary Engaging patients—defined broadly as individuals with lived experience of a given condition, family members, caregivers, and the organisations that represent them—as partners in research is a priority for policymakers, funders, and the public. Nonetheless, formal efforts to engage patients are absent from most studies, and models to support meaningful patient engagement in clinical anaesthesia research have not been previously described. Here, we review our experience in developing and implementing a multifaceted patient engagement strategy within the Regional Versus General Anesthesia for Promoting Independence After Hip Fracture (REGAIN) surgery trial, an ongoing randomised trial comparing spinal vs general anaesthesia for hip fracture surgery in 1600 older adults across 45 hospitals in the USA and Canada. This strategy engaged patients and their representatives at both the level of overall trial oversight and at the level of individual recruiting sites. Activities spanned a continuum ranging from events designed to elicit patients' input on key decisions to longitudinal collaborations that empowered patients to actively participate in decision-making related to trial design and management. Engagement activities were highly acceptable to participants and led to concrete changes in the design and conduct of the REGAIN trial. The REGAIN experience offers a model for future efforts to engage patients as partners in clinical anaesthesia research, and highlights potential opportunities for investigators to increase the relevance of anaesthesia studies by incorporating patient voices and perspectives into the research process.

Increasing number of very old patients (> 80 year old) are presenting for invasive procedures and surgeries. This review addresses perioperative outcomes after cardiac and non-cardiac surgery, in octogenarians and older patients. The overall rates of major upper abdominal cancer resections in octogenarians are increasing over time. Postoperative mortality, postoperative admission to the intensive care unit, and discharge to non-home disposition, after emergency general surgery, were strongly associated with age greater than 80 years. Though acceptable, perioperative morbidity and mortality tends to increase non-linearly after the age of 75 years in patients undergoing cardiac operations. Clinician-centric outcomes continue to dominate outcome reporting. Octogenarians have higher risk of mortality and increased rates of complications, both after cardiac and non-cardiac surgeries. Perioperative care is more resource intensive in the elderly. It is important to keep these factors in mind when contemplating interventions in very elderly individuals.

Objective The types of agents used for monitored anesthesia care (MAC) and their possible differential effects on outcomes have received less study despite increased use over general anesthesia (GA) in transfemoral aortic valve replacements (TAVRs). In this pilot analysis of patients undergoing TAVR using MAC, the authors described the anesthetic agents used and sought to investigate the possible association of anesthetic agent choice with outcomes and the extent to which total weight and time-adjusted doses of anesthetics declined with increasing 10-year age increments. Design Retrospective observational study. Setting Tertiary teaching hospital. Participants Ninety-three participants scheduled to undergo TAVR, with a primary plan of conscious sedation between November 2014 and June 2016, were included. Intervention None. Measurements and Main Results Types of MAC were divided into 4 primary groups, but 2 groups were focused: propofol (n = 39) and dexmedetomidine plus propofol (n = 34). Conversion to GA occurred in 6 participants (6.45%) and was not associated with the type of sedation received. The authors also compared patients who received dexmedetomidine with those who did not in accordance with their a priori analytic plan. There were no associations between the use of dexmedetomidine and postoperative delirium or intensive care unit/hospital length of stay. No significant trends in medication dose adjustments were seen across increasing 10-year age increments. Conclusions A wide breadth of MAC medications is in use among TAVR patients and does not support differences in outcomes. Despite recommendations to reduce anesthetic drug dosing in the elderly, no significant trends in dose reduction with increasing age were noted.

Purpose of review This review discusses the pharmacology of contemporary anesthetic medications in geriatric patients, neurophysiological changes with aging, current recommendations for dosing anesthetic drugs. It also addresses current practice patterns and ongoing studies, which are likely to affect future anesthetic drug management in the elderly. Recent findings Potency of anesthetic drugs is increased in the elderly. In addition to changes at the receptor level, neurophysiological changes in functional connectivity with aging contributes to increased sensitivity of anesthetic drugs. However, the extent of reduction is underappreciated by the practitioners and dose adjustment is not uniformly applied in practice. Large database studies demonstrate association of short-term intraoperative hypotension and CNS depression, to poor perioperative outcomes. These perturbations are probably of greater consequence in frail, elderly patients with reduced reserves. Summary Anesthetic dosing should be more closely age-adjusted to prevent anesthetic-induced hypotension and increased depth of anesthesia in the elderly. Pharmacologic studies are required in the elderly population (>80 years).

Red blood cell (RBC) transfusion has been linked to increased morbidity and mortality. However, strict RBC transfusion recommendations recently have been questioned. The aim of this study was to investigate the short- and long-term mortality outcomes after RBC transfusion in patients undergoing coronary artery bypass graft surgery (CABG).This was a retrospective medical record review.Tertiary care academic medical center.The study included patients who underwent CABG from June 2006 to May 2013.Adult (18 years) cardiac surgery patients who were admitted to the cardiothoracic intensive care unit in a tertiary care academic medical center from June 2006 to May 2013 were collected. In all, 2,180 patients who underwent CABG surgery were included into propensity-score matching analyses, which were matched 1:1. Patients who did not receive transfusion of packed red blood cells (PRBC) (n = 937) were compared with those who received 1 to 5 U (n = 1,113). The study outcomes included mortality rates at 1, 3, and 6 months (short-term) and 1, 2, 3, and 4 years (long-term).No statistical significant differences were found for the 1-month (2% v 1.1%, p = 0.292), 3-month (2.9% v 2%, p = 0.396), or 6-month mortality rate (4.3% v 3.4%, p = 0.602) in 446 patients with 1 to 5 U versus 446 matched patients with no PRBC transfusion. Patients in the transfused group compared with those in the no-transfusion group had statistically significant higher 3-year mortality rate (11% v 6.7%; hazard ratio, 1.64; 95% confidence interval, 1.03-2.63; p = 0.038).In the present study, patients undergoing CABG surgery and receiving6 U of PRBC did not have statistically increased risk for in-hospital mortality and up to 2 years postoperatively. A modestly statistically significant difference was noted at 3 years. However, cumulatively, there was no statistical difference between the transfused and nontransfused groups at 4 years. Further studies are needed to confirm the findings and define the population that will benefit the most from blood transfusion.

It is recommended to correct intravenous induction doses by up to 50% for patients older than 65 years. The objectives were to determine (a) the degree to which anesthesia providers correct induction doses for age and (b) additionally adjust for American Society of Anesthesiologists physical status (ASA-PS) class (severity of illness) and (c) whether postinduction hypotension is more common among patients aged65.Retrospective chart review.Academic medical center.A total of 1869 adult patients receiving general anesthesia for GI surgical procedures from February 2013 to January 2014.Patients were divided into 3 age groups (age65, 65-79, ≥80 years) and then further stratified into ASA-PS class (I/II vs III/IV). Multiple pairwise comparisons were conducted using Welch t tests for continuous variables to determine whether dosing was different for the older groups vs the younger group; separate analyses were performed within and across ASA-PS class. This approach was also used to determine differences in mean arterial pressure change in the older groups vs the younger group, whereas the rates of hypotension among different age groups were compared by Cochran-Armitage trend test.No significant decrease in dosing between age groups was observed for fentanyl and midazolam. For propofol, there was a significantly lower dosing for older patients: 17% for patients aged 65-79 and 29% for those aged80, which was still in less than the recommendations. An inverse relationship was observed between propofol dosing and ASA-PS class, but no consistent relationship was noted for fentanyl and midazolam. There were a significantly larger drop in mean arterial pressure and a greater likelihood of hypotension following induction in patients aged 65-79 years and80 years as compared with those aged65 years.This study shows that the administered dose of anesthetic induction agents is significantly higher than that recommended for patients older than 65 years. This failure to age-adjust dose may contribute to hypotensive episodes.

Development of hyperglycemia after major operations is very common and is modulated by many factors. These factors include perioperative metabolic state, intraoperative management of the patient, and neuroendocrine stress response to surgery. Acute insulin resistance also develops perioperatively and contributes significantly to hyperglycemia. Hyperglycemia is associated with poor outcomes in critically ill and postsurgical patients. A majority of the investigations use the term "hyperglycemia" very loosely and use varying thresholds for initiating treatment. Initial studies demonstrated improved outcomes in critically ill, postsurgical patients who received intensive glycemic control (IGC) (target serum glucose

To determine if recommendations regarding perioperative beta-blocker therapy were followed by an increase in the number of eligible presurgical patients receiving beta-blockers and the number achieving the recommended heart rate (HR60 beats per minute [bpm]).Retrospective, observational study.Tertiary-care teaching hospital.The records of all 718 patients who underwent elective vascular surgery or coronary artery bypass grafting between January 2001 and March 2002 (pre-guideline) and those who did so between April 2002 and September 2003 (post-guideline) were reviewed. Percentage of eligible patients who received beta-blockers preoperatively and the target HR achieved in pre-guideline versus post-guideline patients were recorded. Differences were assessed using the unpaired t test and chi2 analysis. A P value of less than 0.05 is reported.Fifty percent of the post-guideline patients in the vascular surgery group were receiving beta-blockers at the time of preanesthetic evaluation versus 48% of pre-guideline patients (P = nonsignificant [NS]). Mean HR in the vascular surgery post-guideline beta-blocker group (70 +/- 14 bpm) was higher than in the pre-guideline beta-blocker group (65 +/- 11 bpm) (P0.01). Only 22% of those vascular surgery patients in the post-guideline group who were taking beta-blockers achieved the target HR of less than 60 bpm versus 29% of the vascular surgery patients taking beta-blockers in the pre-guideline group (P = NS). In the coronary artery bypass grafting group, 80% of post-guideline patients received beta-blocker before anesthesia assessment versus 75% of pre-guideline patients (P = NS). Mean HR in the post-guideline beta-blocker group (67 +/- 15 bpm) was similar to the pre-guideline beta-blocker group (64 +/- 13 bpm) (P = NS). Only 28% of the post-guideline patients who were receiving beta-blockers achieved the target HR of less than 60 bpm, which was not significantly different from the 17% achieved in the pre-guideline group (P = NS).At our institution, preoperative beta-blocker use was not significantly changed by publication of the recommendations.

Aging involves changes in several physiologic processes that lead to decreased volumes of distribution, slowed metabolism, and increased end-organ sensitivity to anesthetics. These changes generally result in increased potency. Elderly patients require less anesthetic medication, but the true extent of reduction is underappreciated and less uniformly practiced. The impact of potential anesthetic drug overdosing on intermediate and long-term outcomes is not fully appreciated. It may be necessary to consider age as a continuous variable for anesthetic drug dosing in older patients rather than treating adult versus elderly patients. Further pharmacologic studies are required in people more than 85 years old.

To quantify the prevalence of perioperative beta-blocker use and its impact on preoperative and preinduction heart rate (HR), in light of the recent publication of specific recommendations regarding perioperative beta-blocker use and desired HR.Retrospective observational study in patients who underwent elective and coronary artery bypass graft (CABG) surgery between January 2001 and March 2002.Tertiary-care teaching hospital.Percentage of eligible patients who received beta-blockers preoperatively and the impact of non-protocol-based beta-blocker therapy on preadmission and preinduction HR were recorded. Differences were assessed with unpaired t test and chi(2) analysis; P.05 was considered significant, with corrections for multiple comparisons.Of the patients who underwent vascular surgery, 9 had documented prior beta-blocker intolerance. Of the remaining 172 patients, 94.8% had indication for perioperative beta-blocker use. However, only 47.7% of the eligible patients received beta-blockers. Of the 155 CABG patients, 74.2% were taking beta-blockers preoperatively. Only 29% of vascular patients and 32% of CABG patients who were receiving beta-blockers had HR less than 60 beats per minute (bpm) at preadmission. The mean preadmission HR in vascular surgery patients was 65.2 +/- 11 and 73.2 +/- 13.8 bpm in beta-blocker and non-beta-blocker patients, respectively (P = .0001). In CABG surgery patients, preadmission HR values were 64.2 +/- 13 and 76.1 +/- 12 bpm in beta-blocker and non-beta-blocker patients, respectively (P = .001). The preinduction HR subsequently increased in the beta-blocker as well as in the non-beta-blocker groups.Only half of the patients who qualify to receive preoperative beta-blockers by current recommendations actually receive them before noncardiac surgery, and the majority of these patients have preadmission and preinduction HR less than 60 bpm. Targeting beta-blocker therapy treatment to an HR less than 60 bpm may not be readily achievable in many patients.

Beta-blockers have emerged as one of the key therapeutic agents that can decrease cardiac morbidity and mortality. Advances in cardiac beta-adrenergic receptor physiology and pharmacology have provided new insights into the beneficial effects of beta-blockers in cardiovascular medicine. Although significant advances have been made, many specific questions still remain to be answered. We will review some of these developments and the current role of beta-blockers in peri-operative medicine.

Use of ultrasound in the acute care setting has become more common in recent years. However, it still remains underutilized in the perioperative management of critical patients. In this review, we aim to increase the awareness of ultrasound as an important diagnostic modality that can be used in the perioperative period to improve patient care. Our main focus will be in describing the diagnostic uses of ultrasound to identify cardiac, pulmonary, airway and vascular diseases commonly encountered in acute care settings.We find that ultrasound can be used in a quick fashion to assess a haemodynamically unstable patient. Protocols are available to use ultrasound as a part of cardiopulmonary resuscitation. Ultrasound can help in deciding fluid vs. pressor treatment by evaluating the inferior vena cava and other cardiac structures.Lung ultrasound can not only help in diagnosing pneumothoracies and effusions but also look at lung recruitment and diaphragmatic movement, hence can aid in deciding extubation strategies. This modality can be utilized for confirmation of endotracheal tube.Recent interest in axillary vein cannulation with ultrasound guidance has gained some momentum.This article covers the recent developments and literature available on point of care ultrasound and its utilization in the perioperative period. We have not covered some other important uses of ultrasound such as abdominal examination looking at the aorta and other abdominal organs. This was beyond the scope of this article.

Certain surgical interventions can perturb the hemostatic system significantly, making the patient prone to intraoperative and postoperative thrombus formation. The consequences of unabated thrombus formation can be devastating. The risk of developing deep vein thrombosis (DVT) after certain surgical procedures can be as high as 40% to 80%, while the incidence of fatal pulmonary embolism is 1% to 5%.11,49 Antithrombotic therapy is usually instituted perioperatively, and has significant impact on the choice of anesthetic technique.1,26 Anticoagulation is an imperative part of vascular reconstructive procedures, as iatrogenic cessation of blood flow and exposure of thrombogenic subepithelial surfaces can act as a nidus for arterial thrombus formation. Furthermore, cardiopulmonary bypass (CPB) procedures with extracorporeal circulation cannot be possible without intraoperative anticoagulation. Intraoperatively, unfractionated heparin (UH) is used most commonly to inhibit coagulation. Although it will likely continue to be used extensively in the near future, newer agents are on the horizon. These agents may be used in clinical situations where heparin is either contraindicated, or where more predictable responses with less side effects are needed. Because of their wide clinical use, it is imperative to be familiar with heparin and the newer anticoagulant agents. Furthermore, surgical interventions, anesthetics, and some commonly used medications affect coagulation. These effects on the hemostatic system will be reviewed, followed by a discussion of antithrombotics, perioperative monitoring, and clinical management. Intraoperative use of thrombolytics and anesthetic implications of anticoagulation will be discussed.

Hyperglycemia in the surgical population is a recognized risk factor for postoperative complications; however, there is little literature to date regarding the management of hyperglycemia in the perioperative period. Here, we detail the strategies that our institutions have employed to identify and treat hyperglycemia in patients with diabetes who present for surgery. Our approach focuses on the recognition of hyperglycemia and metabolic abnormalities, control of glucose levels via insulin infusion when needed, monitoring for hypoglycemia and a comprehensive multidisciplinary approach that provides standardized recommendations for patients at all points in care as they transition from the preoperative clinic into the operating room, and then into the hospital.

Patients with coronary stents undergoing non-cardiac surgery are at increased risk of major adverse cardiovascular events perioperatively. Impeccable patient care and communication between all members of the healthcare team will minimize this risk. The dominant risk factor for stent thrombosis and major adverse cardiovascular events is the interruption of dual antiplatelet therapy (e.g. aspirin and clopidogrel). If clopidogrel therapy has to be interrupted due to increased risk of bleeding, continuation of aspirin is strongly recommended to reduce the risk of stent thrombosis. The interval between percutaneous coronary interventions and operation is the next major risk factor for stent thrombosis. The incidence of major adverse cardiovascular events is inversely related to this interval, with the highest mortality rate occurring

P ATIENTS WHO HAVE significant cardiac disease do poorly perioperatively. Goldman et al’ proposed the landmark Cardiac Risk Index, believing that if patients could be stratified preoperatively according to their risk of suffering cardiac events, appropriate management would reduce perioperative cardiac morbidity and mortality. Goldman’s Cardiac Risk Index Score was used extensively for cardiac risk assessment, but its limitations were soon recognized. Jeffrey et al? demonstrated that the incidence of cardiac complications in patients who had undergone abdominal aortic procedures was higher than that predicted by the Cardiac Risk Index. A high prevalence of occult asymptomatic coronary artery disease was thought to be the reason for significant cardiac morbidity. Hertzer et al3 reported a 90% prevalence of angiographically proven coronary artery disease, 60% of which was severe, in patients who presented for vascular surgery. Exercise stress testing was of limited value in vascular patients because of their limited exercise tolerance. No reliable way of assessing coronary artery disease was available unless a significant number of cardiac catheterization procedures were to be performed in vascular surgery patients. Concurrently, dipyridamole-thallium imaging (DTI) was introduced in clinical practice as a means of assessing myocardial blood supply. This test had a number of advantages compared with cardiac catheterization. It was noninvasive; was not dependent on the level of exercise achieved by patients; and it defined the location and extent of myocardium at risk (redistribution), permanently damaged (fixed defect), or normal. Absence of redistribution on DTI was reported to signify virtually no risk of sustaining a perioperative myocardial event (negative predictive value, 95% to lOO%).4 With such a high negative predictive value, DTI was rapidly accepted as the most appropriate test for cardiac risk assessment in vascular surgery patients. Should DTI be recommended as a routine preoperative test in patients scheduled for vascular surgery? The author believes that DTI should not be recommended as a routine preoperative test. This conclusion is based on several factors, which are discussed as follows: (I) the true value of the test in cardiac risk stratification, (2) the effect of a positive DTI test on the perioperative management of the patient and overall outcome, (3) the impact of current incidence of the disease and patient outcome on the utility of DTI, and (4) the cost involved. The major shortcomings of most of the initial studies that showed the high negative predictive value of DTI was that they were retrospective and associated with a selection bias. The results were available to the physicians and influenced their anesthetic and surgical management.5 Prospective studies have not supported these retrospective observations.6-Q Mangano et al6 studied 60 consecutive vascular surgery patients who underwent DTI preoperatively. Caregivers were blinded to DTI results, and no significant difference in perioperative ischemia was noted among patients with normal DTI, with fixed defects, or with thallium redistribution.‘j Baron et al,7 in their study of 457 patients who underwent abdominal aortic aneurysm repairs, showed that the presence of clinical evidence of coronary artery disease and old age were the most important preoperative predictors of an adverse cardiac event, rather than thallium redistribution. Similarly, Seeger et al* could not find a significant difference in cardiac complications between patients with positive DTI (redistribution) and negative DTI (fixed or no defect). Roghi et al9 corroborated these findings in 220 vascular surgery patients and reported that redistribution defects had limited sensitivity (38%) and specificity (63%) to predict adverse cardiac outcomes. Positive predictive value and negative predictive value of redistribution were 14% and 87% in their study.g With the benefits of DTI in question, Eagle et ali0 evaluated the advantage of combining clinical indices with DTI results. DTI per se did not enhance the ability to predict perioperative cardiac morbidity in patients who were already assessed by clinical criteria to be at low risk of sustaining cardiac problems (ie, no Eagle’s criteria: Q waves, diabetes mellitus, age > 70 years, angina, ventricular arrhythmias). Similarly, in patients who had three or more of the criteria defined by Eagle, the chance of having significant coronary artery disease and sustaining perioperative events was high. The presence of thallium redistribution raised the risk only from 50% to 64%; and even in the absence of thallium redistribution, the event rate was 33%.t” Eagle et alto suggested that DTI is indicated in determining the myocardium at risk in patients who are at an intermediate risk by clinical criteria (one or two of Eagle’s criteria). Based on the results of DTI, this selective patient population can then be classified as low or high risk. This suggestion has been validated further in a cohort of 1,081 vascular surgical patients by L’italien et al and meta-analysis of DT imaging (19841994) for risk stratification.r*~** These investigations support that DTI has only a limited role in a selective subset of vascular surgery patients, and routine preoperative screening is not advocated. Another factor that the proponents of DTI have promoted arduously is its value in predicting long-term morbidity and mortality. This is an important observation, but it should not be extrapolated to mean petioperative benefit. It is becoming more evident that it may be more prudent to consider DTI in the overall management of coronary artery disease patients, independent of the plans for surgery. The value of DTI in risk stratification in vascular surgery patients has been discussed (see earlier). It is of more limited value when considering the impact of a positive test on perioperative management. The chance of sustaining a pexioperative myocardial infarction is fourfold greater in a patient with a

Fat embolism refers to the presence of fat droplets within the peripheral and lung microcirculation with or without clinical sequelae. The pathologic consequences of fat embolism are well recognized. Fat embolism is most often associated with trauma and orthopedic injuries. Fat embolism syndrome (FES) is a serious manifestation of fat embolism that involves a cascade of clinical signs such as petechial rash, deteriorating mental status, and progressive respiratory insufficiency, usually occurring within 24 hours of injury. This article reviews the definition, epidemiology, etiology, pathophysiology, clinical presentation, diagnosis, management, and prognosis of FES.

Objective: Several studies suggest that cardiac troponin-I (cTn-I) is a more sensitive indicator of cardiac injury compared with other biochemical markers of injury, but the strategy with the highest diagnostic yield (true positive and true negative) for perioperative surveillance is unknown. The authors undertook a prospective evaluation of the perioperative incidence of myocardial infarction (MI) and evaluated surveillance strategies for the diagnosis of MI. Design: Prospective, cohort study. Setting: Two university hospitals. Participants: Four hundred sixty-seven high-risk patients requiring noncardiac surgery. Interventions: None. Measurements and Main Results: The diagnosis of myocardial injury was determined by cardiac protein markers combined with either postoperative changes on 12-lead electrocardiography or 1 of 3 clinical symptoms consistent with MI (chest pain, dyspnea, requirement for hemodynamic support). A receiver operating characteristic curve evaluating troponin in the diagnosis of MI revealed a value of 2.6 ng/mL as having the highest sensitivity and specificity. The sensitivity and specificity of cTn-I value ≥2.6 ng/mL, troponin ≥1.5 ng/mL, total creatine kinase (CK) ≥170 IU/L with MB ≥5%, and CK-MB ≥8 ng/mL were compared. Surveillance strategies were determined on a subset of patients (n = 257). The incidence of MI was 9.0% by cTn-I ≥2.6 ng/mL criteria, 19% by cTn-I ≥1.5 ng/mL, 13% by CK-MB mass, and 2.8% by CK-MB%. The specificity of cTn-I ≥2.6 ng/mL as an indicator of MI was 98%, and its positive predictive value (PPV) was 85%. Cardiac troponin-I ≥2.6 ng/mL had equal specificity but greater PPV than the cTn-I ≥1.5 ng/mL (specificity 98% and PPV 79%). If surveillance of cTn-I ≥2.6 ng/mL was used to detect MI, then the strategy with the highest diagnostic yield was surveillance on postoperative days 1, 2, and 3. Conclusions: Perioperative cardiac injury continues to occur frequently after noncardiac surgery, as detected by cTn-I. Serial monitoring of cardiac troponin-I on postoperative days 1, 2, and 3 provides the strategy with the highest diagnostic yield for surveillance of MI.

Patients undergoing vascular surgery have a high risk of suffering major postoperative cardiac events.Preoperative myocardial ischemia as detected by Holter monitoring identifies a high-risk subgroup whose postoperative ischemia, similarly detected, seems to herald major cardiac events. In this stud