OBJECTIVE: The failure to wean from mechanical ventilation is related to worse outcomes after cardiac surgery. The aim of this study was to evaluate whether the serum level of B-type natriuretic peptide is a predictor of weaning failure from mechanical ventilation after cardiac surgery. METHODS: We conducted a prospective, observational cohort study of 101 patients who underwent on-pump coronary artery bypass grafting. B-type natriuretic peptide was measured postoperatively after intensive care unit admission and at the end of a 60-min spontaneous breathing test. The demographic data, hemodynamic and respiratory parameters, fluid balance, need for vasopressor or inotropic support, and length of the intensive care unit and hospital stays were recorded. Weaning failure was considered as either the inability to sustain spontaneous breathing after 60 min or the need for reintubation within 48 h. RESULTS: Of the 101 patients studied, 12 patients failed the weaning trial. There were no differences between the groups in the baseline or intraoperative characteristics, including left ventricular function, EuroSCORE and lengths of the cardiac procedure and cardiopulmonary bypass. The B-type natriuretic peptide levels were significantly higher at intensive care unit admission and at the end of the breathing test in the patients with weaning failure compared with the patients who were successfully weaned. In a multivariate model, a high B-type natriuretic peptide level at the end of a spontaneous breathing trial was the only independent predictor of weaning failure from mechanical ventilation. CONCLUSIONS: A high B-type natriuretic peptide level is a predictive factor for the failure to wean from mechanical ventilation after cardiac surgery. These findings suggest that optimizing ventricular function should be a goal during the perioperative period.

OBJECTIVES: The anesthetic gas xenon is reported to preserve hemodynamic stability during general anesthesia. However, the effects of the gas during shock are unclear. The objective of this study was to evaluate the effect of Xe on hemodynamic stability and tissue perfusion in a canine model of hemorrhagic shock. METHOD: Twenty-six dogs, mechanically ventilated with a fraction of inspired oxygen of 21% and anesthetized with etomidate and vecuronium, were randomized into Xenon (Xe; n = 13) or Control (C; n = 13) groups. Following hemodynamic monitoring, a pressure-driven shock was induced to reach an arterial pressure of 40 mmHg. Hemodynamic data and blood samples were collected prior to bleeding, immediately after bleeding and 5, 20 and 40 minutes following shock. The Xe group was treated with 79% Xe diluted in ambient air, inhaled for 20 minutes after shock. RESULT: The mean bleeding volume was 44 mL.kg-1 in the C group and 40 mL.kg-1 in the Xe group. Hemorrhage promoted a decrease in both the cardiac index (p<0.001) and mean arterial pressure (p<0.001). These changes were associated with an increase in lactate levels and worsening of oxygen transport variables in both groups (p<0.05). Inhalation of xenon did not cause further worsening of hemodynamics or tissue perfusion markers. CONCLUSIONS: Xenon did not alter hemodynamic stability or tissue perfusion in an experimentally controlled hemorrhagic shock model. However, further studies are necessary to validate this drug in other contexts.

The pandemic novel influenza A (H1N1) infection was considered widespread in Brazil on July, 2009. Since then, 9.249 cases were confirmed in Brazil, most of them concentrated in São Paulo. The Hospital das Clínicas of the University of São Paulo is a reference center for H1N1 cases in São Paulo. The purpose of this review is to analyze the evidence concerning diagnosis, prevention, and treatment of novel influenza A (H1N1) infection. In addition, we propose guidelines for the management of this pandemic emphasizing Hospital das Clínicas "bundles" for the control of the pandemic novel influenza A (H1N1).

The pandemic novel influenza A (H1N1) infection was considered widespread in Brazil on July 16, 2009. Since then, 46,810 cases of acute respiratory syndrome have been reported in Brazil, most of them concentrated in São Paulo. Through September 16, we have confirmed 9,249 cases of novel influenza A H1N1in Brazil, including 699 deaths. The mortality rate observed in Brazil is 0.47/100,000 inhabitants and varies according to region. In this period, São Paulo registered 3733 cases (40.3% of the total) of novel influenza A (H1N1) infection and 327 deaths, reflecting a mortality rate of 0.79/100,000 inhabitants. The Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HC) is a reference center for H1N1 cases in São Paulo. During the winter of 2009, 472 patients in this hospital were diagnosed with H1N1 infection; of these, 210 were admitted, and 16 died. To control this pandemic and to provide adequate care for these patients, the Hospital das Clínicas implemented "bundles" including prevention strategies, an epidemiologic surveillance service, availability of fast diagnosis, antiviral treatment and training of staff. The purpose of this manuscript is to describe the epidemiologic features of novel human influenza A (H1N1) infection in the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo during the winter period of the 2009 pandemic.