Brain natriuretic peptide (BNP), also called B-type natriuretic peptide, is a member of a family of structurally related hormones, the natriuretic peptides. Current data suggest that measurement of BNP plasma concentrations is a useful tool in the diagnosis of acute heart failure in patients presenting to an emergency department with acute dyspnea. Furthermore, BNP constitutes a promising new marker of prognosis after an acute coronary syndrome episode and in patients with chronic heart failure. Nesiritide, the human recombinant form of BNP, is a new vasodilator used in the treatment of acute heart failure that has several potential advantages over current drug therapy.

Chronotropic incompetence (CI) is the inability of heart rate response to meet metabolic demand. CI is associated with sinus node dysfunction, atrial fibrillation, or structural heart disease, and can lead to functional impairment. We report the case of a 34-year-old man with CI secondary to sinus node dysfunction who demonstrated significant improvement in functional capacity with rate-responsive pacing. Therapy for CI should be guided by the treatment of the underlying cause with consideration for rate-responsive pacing in symptomatic patients. The prognosis of CI is variable and dependent on underlying etiology.

While most attempts at developing a treatment for pulmonary emphysema have focused on the use of elastase inhibitors to reduce elastic fiber damage and the loss of alveoli, this laboratory has developed a method of preventing such injury by the intratracheal administration of hyaluronan (HA). Animals treated with HA prior to the induction of experimental emphysema develop significantly less disease than untreated controls. The protective effect of HA may be related to its ability to bind to lung elastic fibers, thereby preventing their breakdown by elastases. Although clinical trials involving nebulized HA are not expected to yield a measurable treatment effect for at least several years, it is proposed that the special ability of this polysaccharide to retain water may increase the elasticity of lung elastic fibers, producing a relatively rapid improvement in pulmonary mechanics. Such an outcome might speed the development of this potential treatment for pulmonary emphysema.

Pulmonary complications remain a major cause of both morbidity and mortality in immunocompromised patients. When such individuals present with radiographic infiltrates, the clinician faces a diagnostic challenge. The differential diagnosis in this setting is broad and includes both infectious and noninfectious processes. Rarely are the radiographic findings classic for one disease, and most potential etiologies have overlapping clinical and radiographic appearances. In recent years, several themes have emerged in the literature on this topic. First, an aggressive approach to identifying a specific etiology is necessary; as a corollary, diagnostic delay increases the risk for mortality. Second, the evaluation of these infiltrates nearly always entails bronchoscopy. Bronchoscopy allows identification of some etiologies with certainty, and often allows for the exclusion of infectious agents even if the procedure is otherwise unrevealing. Third, early use of CT scanning regularly demonstrates lesions missed by plain radiography. Despite these advances, initial therapeutic interventions include the use of broad-spectrum antibiotics and other anti-infectives in order to ensure that the patients is receiving appropriate therapy. With the results of invasive testing, these treatments are then narrowed. Frustratingly, outcomes for immunocompromised patients with infiltrates remain poor.

Bronchodilators form the foundation of symptomatic treatment of COPD. Several long-acting bronchodilators are now available for use in COPD, but publications of large-scale studies of their efficacy have, for the most part, postdated the publication of major clinical guidelines. This article provides a critical review of large (> or =50 patients), double-blind, clinical trials of three long-acting bronchodilators in COPD (the once-daily anticholinergic tiotropium, and the twice-daily beta(2)-agonists formoterol and salmeterol) within the context of the objectives of treatment defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. Fourteen published studies were identified, of which 12 studies were published since the release of the GOLD guidelines. All three long-acting bronchodilators were found to effectively improve lung function; however, they differed in their effects on outcomes other than bronchodilation, with salmeterol demonstrating inconsistent efficacy compared with placebo in preventing exacerbations and improving health status, and only tiotropium demonstrating consistent superiority to the short-acting bronchodilator ipratropium. Based on this review, a treatment algorithm for the introduction of long-acting bronchodilators to patients with COPD is proposed, which includes the use of long-acting bronchodilators early in the treatment algorithm.

Cost-effectiveness information can help health-system participants make decisions about diagnostic or therapeutic innovations that are more expensive but incrementally safe and effective. However, these analyses cannot help decide whether a less expensive approach is "sufficient" and funds ought to be allocated to other medical issues entirely. At present, formulary committees are commonly determining that medications are "mostly equivalent" in efficacy and safety and choosing individual medications or classes of medications based on cost. Clinicians may not agree with these decisions and will need to understand their rationale. For prophylaxis of venous thromboembolism after hip and knee replacement and hip fracture surgery, many preventive modalities are available with different safety and efficacy profiles and different costs. It is possible to list the important safety and efficacy outcomes of prophylaxis, estimate their incidences and costs, and "model" comparisons of one modality vs another, in order to help decide whether one is preferable.

Venous thromboembolism (VTE) prophylaxis is indicated while in the hospital after major surgery. There is evidence that the prevalence of asymptomatic deep-vein thrombosis, detected by routine venography after major orthopedic surgery, is lower at hospital discharge in patients who have received 10 days rather than 5 days of prophylaxis. This observation supports the current American College of Chest Physicians (ACCP) recommendation for a minimum of 7 to 10 days of prophylaxis after hip and knee replacement, even if patients are discharged from the hospital within 7 days of surgery. As risk of VTE persists for up to 3 months after surgery, patients at high risk for postoperative VTE may benefit from extended prophylaxis (eg, an additional 3 weeks after the first 7 to 10 days). Extended prophylaxis with low-molecular-weight heparin (LMWH) reduces the frequency of postdischarge VTE by approximately two thirds after hip replacement; however, the resultant absolute reduction in the frequency of fatal pulmonary embolism is small (ie, estimated at 1 per 2,500 patients). Indirect evidence suggests that, compared with LMWH, efficacy of extended prophylaxis after hip replacement is greater with fondaparinux, similar with warfarin, and less with aspirin. Extended prophylaxis is expected to be of less benefit after knee than after hip replacement. In keeping with current ACCP recommendations, at a minimum, extended prophylaxis should be used after major orthopedic surgery in patients who have additional risk factors for VTE (eg, previous VTE, cancer). If anticoagulant drug therapy is stopped after 7 to 10 days, an additional month of prophylaxis with aspirin should be considered.

Adjusted doses of oral warfarin sodium or fixed doses of subcutaneous low-molecular-weight heparin (LMWH) are the standard approaches for preventing venous thromboembolism following major orthopedic surgery of the legs. In recent years, new anticoagulants have been compared with either LMWH or warfarin. The optimal timing for the first dose of LMWH prophylaxis and of the new anticoagulants is controversial. Recent clinical trials of LMWH and of newer anticoagulants have provided new information on the relationship between the timing of the first anticoagulant dose and the efficacy and safety of thromboprophylaxis after major orthopedic surgery. These data on the optimal timing of initiating prophylaxis come from limited direct randomized comparisons of different timing with the same anticoagulant, subgroup analysis of large studies with a single anticoagulant, indirect comparisons across studies in systematic reviews, and single randomized trials comparing different anticoagulants. In the direct comparison of the same anticoagulant, preoperative initiation of the same regimen of LMWH (dalteparin) increased major bleeding, without improved antithrombotic efficacy compared to the early postoperative regimen. Fondaparinux, 2.5 mg, begun 6 h postoperatively is more effective and as safe as the currently approved regimens of enoxaparin begun either 12 h preoperatively, or 12 to 24 h postoperatively, in patients undergoing major orthopedic surgery. In a subgroup analysis of several large randomized trials, fondaparinux, 2.5 mg, begun < 6 h postoperatively was associated with increased major bleeding, without improved efficacy. The results of indirect comparisons also favor the use of a 6-h postoperative starting time for the first dose, while the single randomized trials comparing different anticoagulants performed to date are not helpful in establishing an optimal time for the first dose. The aggregate clinical research evidence supports the following general conclusions about the relationship between the timing of the first anticoagulant dose and the efficacy and safety of prophylaxis: (1) preoperative initiation is not required for good efficacy and, when begun within 2 h of surgery, increases major bleeding; (2) initiation at 6 h postoperatively is effective and not associated with increased major bleeding; (3) initiation < 6 h postoperatively increases major bleeding, without improved efficacy; thus, 6 h appears to be the threshold for early postoperative administration; and (4) initiation 12 to 24 h postoperatively may be less effective than initiation at 6 h, but further randomized trials comparing the same anticoagulant initiated at different times postoperatively (eg, 6 h vs 12 h) are required to establish definitively the optimal timing of the first anticoagulant dose.

Fondaparinux, a selective inhibitor of factor Xa, is the first of a new class of antithrombotic compounds, the synthetic pentasaccharides. Its benefit-to-risk ratio in preventing venous thromboembolism after major orthopedic surgery was investigated in four randomized, double-blind international phase III trials in patients undergoing surgery for hip fracture, elective hip replacement, and major knee surgery. Compared to enoxaparin, fondaparinux administered at a subcutaneous dose of 2.5 mg qd, starting postoperatively, reduced the overall incidence of venous thromboembolism up to day 11 by 55.2% (p < 0.001). The incidence of clinically relevant bleeding was low and did not differ between the two groups. Overall, fondaparinux achieved optimal efficacy and safety when treatment was initiated > or =6 h after the surgical procedure. In a further randomized double-blind trial, 4 weeks of prophylaxis with fondaparinux after hip fracture surgery reduced the risk of venous thromboembolism by 96% as compared to 1 week of prophylaxis, and was well tolerated. Fondaparinux has been recently approved for use in thromboprophylaxis after major orthopedic surgery. The clinical development of fondaparinux in other thromboprophylactic indications is ongoing.

Fondaparinux is the first of a new class of antithrombotic compounds, the synthetic pentasaccharides. By binding rapidly and strongly to antithrombin, its sole physiologic target in plasma, fondaparinux catalyzes specifically the inhibition of factor Xa, which results in effective and linear dose-dependent inhibition of thrombin generation. Fondaparinux does not bind to platelets. Its antithrombotic effect has been demonstrated in several animal models of arterial and venous thrombosis. At equivalent antithrombotic concentrations, fondaparinux induced less bleeding than unfractionated heparin in experimental bleeding models. Furthermore, it did not cross-react with sera from patients with heparin-induced thrombocytopenia. Administered subcutaneously, the absorption of fondaparinux is complete, rapid, and independent of dose. It has a linear pharmacokinetic profile, and its half-life of approximately 17 h allows for once-daily dosing. Fondaparinux is almost completely excreted by the kidneys. Owing to the limited intrasubject and intersubject variability, routine monitoring and dose adjustments should not be required for most patients. Fondaparinux has been approved for use in thromboprophylaxis after major orthopedic surgery, where it has demonstrated its efficacy compared to a low-molecular-weight heparin. Its clinical development in other indications is ongoing.

Although venous thromboembolism (VTE) is an important cause of morbidity and mortality in critical care unit patients, the risk of VTE and its prevention have been poorly characterized in this population. Evidence-based thromboprophylaxis guidelines are also not available for these critically ill patients.

The "elimination" of the left atrial appendage (LAA) seems to be an attractive alternative to oral anticoagulation in the treatment of atrial fibrillation, especially in patients with contraindications to oral anticoagulation therapy. The LAA, however, plays an important role in the maintenance and regulation of the cardiac function, in arterial hypertension, atrial fibrillation, coronary heart disease, valvular heart disease, and heart failure. Data, mainly from animal studies, indicate that elimination of the LAA may impede thirst in patients with hypovolemia, may impair hemodynamic response to volume or pressure overload, may decrease cardiac output, and may promote heart failure. It may have adverse effects in humans as well. Further studies on the hemodynamic and neurohumoral consequences of left atrial appendage elimination are required to advance our understanding of LAA physiology and pathophysiology.

The available clinical guidelines have been successful in improving awareness of the inflammatory nature of asthma and have promoted the use of inhaled corticosteroids (ICSs) to achieve long-term control of symptoms. Because of lingering concerns over the possible adverse consequences of ICS use, an expert panel was convened with a mandate to identify the critical questions that impact decisions regarding the use of ICSs and to evaluate the available evidence with respect to risk.

To review the published experience with gadolinium-enhanced magnetic resonance angiography (MRA) for the detection of acute pulmonary embolism (PE) in order to test the hypothesis that gadolinium-enhanced MRA may be potentially sensitive and specific enough to include it among diagnostic alternatives in the evaluation of patients with suspected PE.

The relationship between sleep-disordered breathing (SDB) and nasal obstruction is unclear. In order to better understand, we performed an extensive computer-assisted review and analysis of the medical literature on this topic. Data were grouped into reports of normal control subjects, patients with isolated nasal obstruction, and those with SDB. We conclude that SDB can both result from and be worsened by nasal obstruction. Nasal breathing increases ventilatory drive and nasal occlusion decreases pharyngeal patency in normal subjects. Nasal congestion from any cause predisposes to SDB. Although increased nasal resistance does not always correlate with symptoms of congestion, nasal congestion typically results in a switch to oronasal breathing that compromises the airway. Moreover, oral breathing in children may lead to the development of facial structural abnormalities associated with SDB. We postulate that the switch to oronasal breathing that occurs with chronic nasal conditions is a final common pathway for SDB.

New therapies for pulmonary arterial hypertension (PAH) improve functional status, quality of life (QOL), and survival. Clinicians must chose between very different therapies without the availability of comparison studies. We constructed a "virtual" clinical trial to help inform these treatment choices.