Renin-angiotensin system antagonists in the perioperative setting: clinical consequences and recommendations for practice.

There are no existing guidelines supporting the withdrawal or continuation of renin-angiotensin-aldosterone system (RAAS) antagonists in the preoperative setting. RAAS antagonists include ACE inhibitors, angiotensin II receptor subtype 1 blockers and direct renin inhibitors (eg, aliskiren), as well as the aldosterone antagonists. The use of these agents before surgery has been associated with a variable incidence of hypotension during the initial 30 min after induction of anaesthesia; however, these hypotensive episodes have not been conclusively linked to any significant postoperative complications, although recent data suggest an increase in postoperative morbidity and mortality in patients undergoing coronary artery bypass grafting. Further studies are required to be able to demonstrate if the organ-protective benefits of RAAS antagonists justify their continuation in the perioperative setting. Temporary withdrawal of RAAS antagonists in these patients may prevent or attenuate intraoperative hypotension and hypovolaemia. Alternatively, the increase in RAAS activity and blood pressure expected with cessation of RAAS antagonist therapy may impair regional circulation secondary to an increase in systemic vascular resistance. Full discussion of the potential implications of perioperative RAAS antagonist therapy with the surgical team is important, and strategies to ensure careful monitoring and maintenance of adequate intravenous volume before induction of anaesthesia are essential.

Outcomes of patients with stable heart failure undergoing elective noncardiac surgery.

OBJECTIVE: To evaluate modern surgical outcomes in patients with stable heart failure undergoing elective major noncardiac surgery and to compare the experience of patients with heart failure who have reduced vs preserved left ventricular ejection fraction (EF). PATIENTS AND METHODS: We retrospectively studied 557 consecutive patients with heart failure (192 EF less than or equal to 40% and 365 EF greater than 40%) and 10,583 controls who underwent systematic evaluation by hospitalists in a preoperative clinic before having major elective noncardiac surgery between January 1, 2003, and March 31, 2006. We examined outcomes in the entire cohort and in propensity-matched case-control groups. RESULTS: Unadjusted 1-month postoperative mortality in patients with both types of heart failure vs controls was 1.3% vs 0.4% (P equals .009), but this difference was not significant in propensity-matched groups (P equals .09). Unadjusted differences in mean hospital length of stay among heart failure patients vs controls (5.7 vs 4.3 days; P less than .001) and 1-month readmission (17.8% vs 8.5%; P less than .001) were also markedly attenuated in propensity-matched groups. Crude 1-year hazard ratios for mortality were 1.71 (95% confidence interval [CI], 1.5-2.0) for both types of heart failure, 2.1 (95% CI, 1.7-2.6) in patients with heart failure who had EF less than or equal to 40%, and 1.4 (95% CI, 1.2-1.8) in those who had EF greater than 40% (P less than .01 for all 3 comparisons); however, the differences were not significant in propensity-matched groups (P equals .43). CONCLUSION: Patients with clinically stable heart failure did not have high perioperative mortality rates in association with elective major noncardiac surgery, but they were more likely than patients without heart failure to have longer hospital stays, were more likely to require hospital readmission, and had a substantial long-term mortality rate.

Bridging the gap between evidence and practice in venous thromboembolism prophylaxis: the quality improvement process.

Venous thromboembolism (VTE) is considered to be the most common preventable cause of hospital-related death. Hospitalized patients undergoing major Surgery and hospitalized patients with acute medical illness have an increased risk of VTE. Although there is overwhelming evidence for the need and efficacy of VTE prophylaxis in patients at risk, only about a third of those who are at risk of VTE receive appropriate prophylaxis. To address the shortfall in VTE prophylaxis, the US Joint Commission and the National Quality Forum (NQF) endorse standardized VTE prophylaxis practices, and are identifying and testing measures to monitor these standards. Hospitals in the USA accredited by Centers for Medicare and Medicaid Services to receive medicare patients will need VTE prophylaxis programs in place to conform to these national consensus standards. This review aims to give background information on initiatives to improve the prevention of VTE and to identify key features of a successful quality improvement strategy for prevention of VTE in the hospital. A literature review shows that the key features of effective quality improvement strategies includes an active strategy, a multifaceted approach, and a continuous iterative process of audit and feedback. Risk assessment models may be helpful for deciding which patients should receive prophylaxis and for matching VTE risk with the appropriate intensity of prophylaxis. This approach should assist in implementing the NQF/Joint Commission-endorsed standards, as well as increase the use of appropriate VTE prophylaxis.

Unrecognized sleep apnea in the surgical patient: implications for the perioperative setting.

UNLABELLED: Anesthesia and surgery both affect the architecture of sleep. Aside from the postoperative effects of anesthesia and surgery, sleep deprivation and fragmentation have been shown to produce apneas or desaturations even in patients without presumed sleep apnea. Recent epidemiologic data have placed the prevalence of obstructive sleep apnea syndrome (OSAS) at about 5% among Western countries. The problem is further hindered by the difficulty in diagnosing OSAS, as patients with OSAS may present for surgery without a prior diagnosis. Clinical suspicion for OSAS may first be recognized intraoperatively. Adverse surgical outcomes appear to be more frequent in OSAS patients. Immediate postoperative complications may intuitively be attributed to the negative effects of sedative, analgesic, and anesthetic agents, which can worsen OSAS by decreasing pharyngeal tone, and the arousal responses to hypoxia, hypercarbia, and obstruction. Later events are, however, more likely to be related to postoperative rapid eye movement (REM) sleep rebound. In the severe OSAS patient, REM sleep rebound could conceivably act in conjunction with opioid administration and supine posture to aggravate sleep-disordered breathing. REM sleep rebound has also been suggested to contribute to mental confusion and postoperative delirium, myocardial ischemia/infarction, stroke, and wound breakdown. Although the data to guide the perioperative management of patients with moderate-to-severe OSAS is scarce, heightened awareness is recommended. The selected use of therapy with nasal continuous positive airway pressure before surgery and after extubation may be beneficial. LEARNING OBJECTIVES: 1. Identify common sleep architectures affected by anesthesia and surgery in the perioperative period. 2. State a perioperative complication in Obstructive Sleep Apnea Syndrome patients. 3. Identify perioperative interventions and management techniques that best facilitate improved obstructive sleep apnea syndrome patient care.

Preventing venous thromboembolism in surgical patients.

Hospital strategies to prevent VTE are important to reduce acute morbidity and mortality as well as the long-term consequences caused by venous stasis syndrome. Patients at low risk (eg, those who are ambulatory or undergoing a same-day procedure) or who are at high risk for bleeding (including those with severe renal impairment) are candidates for nonpharmacologic strategies for thromboembolic prophylaxis. Mechanical devices are effective if used appropriately, but compliance is a challenge. Patients who require a hospital stay of more than a day or two should receive a medication-based strategy, preferably using LMWH or fondaparinux. Patients undergoing hip replacement should receive extended prophylaxis with LMWH.

Venous thromboembolism: epidemiology, characteristics, and consequences.

Venous thromboembolism (VTE) and its manifestations, including deep vein thrombosis (DVT) and pulmonary embolism (PE), pose a life-threatening health problem for thousands of people each year. The diagnosis of VTE is frequently missed, however, because few signs and symptoms are recognized. Symptoms of DVT may include pain, erythema, tenderness, and swelling of the affected limb, whereas PE often presents as sudden breathlessness with chest pain, or collapse with shock in the absence of other causes. Greater awareness of the epidemiology of VTE, the consequences of VTE, and the risk factors for VTE can help health care providers take appropriate preventive measures to reduce the incidence of VTE.

Anticoagulation in special patient populations: are special dosing considerations required?

Optimal dosing of low-molecular-weight heparin (LMWH) therapy has not yet been established for patients with morbid obesity or renal insufficiency or for pregnant women. Monitoring of anti-Xa levels appears to be helpful in guiding LMWH dosing in all of these patient groups. Use of fondaparinux in these populations has yet to be defined. Cancer patients are at particular risk of venous thromboembolism and generally require escalated and/or prolonged anticoagulation with intense monitoring of therapy.

Current and emerging options in the management of venous thromboembolism.

Venous thromboembolism (VTE) is a common disease whose diagnosis is challenging. The best diagnostic approaches combine the patient's pretest clinical probability of disease with D-dimer testing and/or diagnostic imaging. In light of several advantages, low-molecular-weight heparins are now recommended over unfractionated heparin for most patients with acute VTE. Newer anticoagulants such as the factor Xa inhibitor fondaparinux also show promise for acute VTE. For chronic management, the duration and intensity of warfarin therapy should be tailored to the individual patient.

Predictors of intraoperative hypotension and bradycardia.

BACKGROUND: Perioperative hypotension and bradycardia in the surgical patient are associated with adverse outcomes, including stroke. We developed and evaluated a new preoperative risk model in predicting intraoperative hypotension or bradycardia in patients undergoing elective noncardiac surgery. METHODS: Prospective data were collected in 193 patients undergoing elective, noncardiac surgery. Intraoperative hypotension was defined as systolic blood pressure <90 mm Hg for >5 minutes or a 35% decrease in the mean arterial blood pressure. Intraoperative bradycardia was defined as a heart rate of <60 beats/min for >5 minutes. A logistic regression model was developed for predicting intraoperative hypotension or bradycardia with bootstrap validation. Model performance was assessed using area under the receiver operating curves and Hosmer-Lemeshow tests. RESULTS: A total of 127 patients developed hypotension or bradycardia. The average age of participants was 67.6 ± 11.3 years, and 59.1% underwent major surgery. A final 5-item score was developed, including preoperative Heart rate (<60 beats/min), preoperative hypotension (<110/60 mm Hg), Elderly age (>65 years), preoperative renin-Angiotensin blockade (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or beta-blockers), Revised cardiac risk index (≥3 points), and Type of surgery (major surgery), entitled the "HEART" score. The HEART score was moderately predictive of intraoperative bradycardia or hypotension (odds ratio, 2.51; 95% confidence interval, 1.79-3.53; C-statistic, 0.75). Maximum points on the HEART score were associated with an increased likelihood ratio for intraoperative bradycardia or hypotension (likelihood ratio, +3.64). CONCLUSIONS: The 5-point HEART score was predictive of intraoperative hypotension or bradycardia. These findings suggest a role for using the HEART score to better risk-stratify patients preoperatively and may help guide decisions on perioperative management of blood pressure and heart rate-lowering medications and anesthetic agents.

Rational use of D-dimer measurement to exclude acute venous thromboembolic disease.

Clinical diagnosis of venous thromboembolic (VTE) disease is often inaccurate because signs and symptoms are nonspecific. Testing for the absence of D-dimer levels in the blood of patients with suspected deep venous thrombosis and pulmonary embolism can assist in ruling out these illnesses. Some highly sensitive D-dimer assays have sufficient specificity to assist in the exclusion of VTE disease. Numerous clinical management trials using D-dimer measurement in association with additional diagnostic tests have shown that it is safe to withhold anticoagulant therapy in selected patients with suspected VTE disease who have negative D-dimer assay results. Applying these diagnostic strategies can potentially decrease the need for radiological testing. The simplicity of measuring D-dimer levels creates the potential for misuse. For safe patient management, clinicians must understand the indications for and limitations of D-dimer measurement in the diagnosis of VTE disease.

Perioperative management of the hospitalized patient.

The hospitalized surgical patient requires a team approach. Because of increasing patient age and complexity of conditions, a comprehensive preoperative evaluation and medical optimization is often necessary to allow the anesthesiologist and surgeon to deliver the best surgical outcome. Surgical patients at an increased risk for postoperative complications should be followed carefully by a medical consultant throughout the hospital stay. This continuity of perioperative care improves the likelihood that postoperative problems, such as delirium, early myocardial ischemia, or VTE, are quickly identified, and appropriate therapeutic interventions are initiated before more serious adverse events occur. Special surgical populations, such as those patients who need perioperative anticoagulation, further benefit from a surgical team that includes a medical specialist. Expertise and close supervision throughout the perioperative period will give the hospitalized surgical patient the greatest chance for a quick and successful recovery.

Venous thromboembolism prophylaxis in the medically ill patient.

All general medical patients should be assessed for clinical risk factors for VTE. The ACCP has recommended that general medical patients with clinical risk factors receive either LDUH twice or three times daily or once-daily LMWH. Current evidence suggests that twice-daily LDUH may not be efficacious enough in the acutely ill medical inpatient. LDUH three times daily may be efficacious in most medical patients; however, it is associated with an increased risk for bleeding. The preferred strategy for prevention in the medically ill population at high to very high risk for VTE is LMWH. For patients who have a high to very high risk for bleeding, nonpharmacologic strategies such as ES or IPC devices are recommended.

The preoperative evaluation: use the history and physical rather than routine testing.

The history and physical examination, rather than routine laboratory, cardiovascular, and pulmonary testing, are the most important components of the preoperative evaluation. The history should include a complete review of systems (especially cardiovascular and pulmonary), medication history, allergies, surgical and anesthetic history, and functional status.

Transitions of care in anticoagulated patients.

Anticoagulation is an effective therapeutic means of reducing thrombotic risk in patients with various conditions, including atrial fibrillation, mechanical heart valves, and major surgery. By its nature, anticoagulation increases the risk of bleeding; this risk is particularly high during transitions of care. Established anticoagulants are not ideal, due to requirements for parenteral administration, narrow therapeutic indices, and/or a need for frequent therapeutic monitoring. The development of effective oral anticoagulants that are administered as a fixed dose, have low potential for drug-drug and drug-food interactions, do not require regular anticoagulation monitoring, and are suitable for both inpatient and outpatient use is to be welcomed. Three new oral anticoagulants, the direct thrombin inhibitor, dabigatran etexilate, and the factor Xa inhibitors, rivaroxaban and apixaban, have been approved in the US for reducing the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation; rivaroxaban is also approved for prophylaxis and treatment of deep vein thrombosis, which may lead to pulmonary embolism in patients undergoing knee or hip replacement surgery. This review examines current options for anticoagulant therapy, with a focus on maintaining efficacy and safety during transitions of care. The characteristics of dabigatran etexilate, rivaroxaban, and apixaban are discussed in the context of traditional anticoagulant therapy.

Prevention and management of venous thromboembolism in the surgical patient: options by surgery type and individual patient risk factors.

BACKGROUND: Current evidence-based guidelines provide recommendations for prophylaxis and treatment of venous thromboembolism (VTE) in a variety of surgical patients. DATA SOURCES: A systematic Ovid Medline search (from 1950 to the present) was conducted for relevant articles using the following search terms: "venous thromboembolism," "thrombophlebitis," "thromboembolism," "pulmonary embolism," "heparin," "low-molecular-weight heparin," "postoperative complications," and "anticoagulants." CONCLUSIONS: Pharmacologic and mechanical approaches are available for VTE prophylaxis, including low-dose unfractionated heparin, low-molecular-weight heparin, vitamin K antagonists, fondaparinux, intermittent pneumatic compression devices, and graduated compression stockings. Permanent inferior vena cava filters are not recommended for primary VTE prophylaxis, although they do have a role in the prevention of pulmonary embolism in patients with recent VTE who cannot have surgery delayed. Retrievable inferior vena cava filters are under investigation for primary VTE prophylaxis in trauma patients. New anticoagulants that inhibit factor Xa and thrombin will soon be available for the prevention and treatment of VTE in surgical patients.