86,658 research outputs found
Positive end-expiratory pressure: How to set it at the individual level
No full textThe positive end-expiratory pressure (PEEP), since its introduction in the treatment of acute respiratory failure, up to the 1980s was uniquely aimed to provide a viable oxygenation. Since the first application, a large debate about the criteria for selecting the PEEP levels arose within the scientific community. Lung mechanics, oxygen transport, venous admixture thresholds were all proposed, leading to PEEP recommendations from 5 up to 25 cmH2O. Throughout this period, the main concern was the hemodynamics. This paradigm changed during the 1980s after the wide acceptance of atelectrauma as one of the leading causes of ventilator induced lung injury. Accordingly, the PEEP aim shifted from oxygenation to lung protection. In this framework, the prevention of lung opening and closing became an almost unquestioned dogma. Consequently, as PEEP keeps open the pulmonary units opened during the previous inspiratory phase, new methods were designed to identify the 'optimal' PEEP during the expiratory phase. The open lung approach requires that every collapsed unit potentially openable is opened and maintained open. The methods to assess the recruitment are based on imaging (computed tomography, electric impedance tomography, ultrasound) or mechanically-driven gas exchange modifications. All the latest assume that whatever change in respiratory system compliance is due to changes in lung compliance, which in turn is uniquely function of the recruitment. Comparative studies, however, showed that the only possible approach to measure the amount of collapsed tissue regaining inflation is the CT scan. In fact, all the other methods estimate as recruitment the gas entry in pulmonary units already open at lower PEEP, but increasing their compliance at higher PEEP. Since higher PEEP is usually more indicated (also for oxygenation) when the recruitability is higher, as occurs with increasing severity, a meaningful PEEP selection requires the assessment of recruitment. The Berlin definition may help in this assessment
Reclassifying acute respiratory distress syndrome
No full textRationale: The ratio of PaO2 to FIO2 (P/F) defines acute respiratory distress syndrome (ARDS) severity and suggests appropriate therapies. Objectives: We investigated 1) whether a 150-mm-Hg P/F threshold within the range of moderate ARDS (100-200 mm Hg) would define two subgroups that were more homogeneous; and 2) which criteria led the clinicians to apply extracorporeal membrane oxygenation (ECMO) in severe ARDS. Methods: At the 150-mm-Hg P/F threshold, moderate patients were split into mild-moderate (n = 50) and moderate-severe (n = 55) groups. Patients with severe ARDS (FIO2 not available in three patients) were split into higher (n = 63) and lower (n = 18) FIO2 groups at an 80% FIO2 threshold. Measurements and Main Results: Compared with mild- moderate ARDS, patients with moderate-severe ARDS had higher peak pressures, PaCO2, and pH. They also had heavier lungs, greater inhomogeneity, more noninflated tissue, and greater lung recruitability. Within 84 patients with severe ARDS (P/F,100 mm Hg), 75% belonged to the higher FIO2 subgroup. They differed from the patients with severe ARDS with lower FIO2 only in PaCO2 and lung weight. Forty-one of 46 patients treated with ECMO belonged to the higher FIO2 group. Within this group, the patients receiving ECMO had higher PaCO2 than the 22 non-ECMO patients. The inhomogeneity ratio, total lung weight, and noninflated tissue were also significantly higher. Conclusions: Using the 150-mm-Hg P/F threshold gave a more homogeneous distribution of patients with ARDS across the severity subgroups and identified two populations that differed in their anatomical and physiological characteristics. The patients treated with ECMO belonged to the severe ARDS group, and almost 90% of them belonged to the higher FIO2 subgroup
Anaerobic metabolism during cardiopulmonary bypass: predictive value of carbon dioxide derived parameters
No full textBACKGROUND:
Hyperlactatemia during cardiopulmonary bypass (CPB) is a common event and is associated to a high morbidity and mortality after cardiac operations. The present study is aimed to identify the possible predictors of hyperlactatemia during CPB among a series of oxygen and carbon dioxide derived parameters measured during CPB.
METHODS:
This is a prospective observational study on 54 patients undergoing cardiac surgery with CPB. Hyperlactatemia was defined as an arterial lactate concentration higher than 3 mMol/L. Serial blood lactate assays have been performed during CPB, and their association to a number of oxygen and carbon dioxide derived parameters was explored.
RESULTS:
Arterial blood lactate concentration was positively correlated to the CPB duration, the carbon dioxide elimination, and the respiratory quotient, and negatively correlated to the presence of the aortic cross-clamping, the body surface area, the ratio between the oxygen delivery and the carbon dioxide production, and the arterial oxygen saturation. Predictors of hyperlactatemia during CPB are a carbon dioxide production higher than 60 mL.min(-1).m(-2), a respiratory quotient higher than 0.9, and a ratio between oxygen delivery and carbon dioxide production lower than 5.
CONCLUSIONS:
Carbon dioxide derived parameters are representative of hyperlactatemia during CPB, as a result of the carbon dioxide produced under anaerobic conditions through the buffering of protons by the bicarbonate system. The carbon dioxide elimination rate measured at the exhaled site of the oxygenator may be used for an indirect assessment of the metabolic state of the patient
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Prental diagnosis of metabolic disease on chorionic villi obtained before the ninth week of pregnancy
No full text[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Reclassifying acute respiratory distress syndrome
No full textRationale: The ratio of PaO2to FIO2(P/F) defines acute respiratory distress syndrome (ARDS) severity and suggests appropriate therapies. Objectives: We investigated 1) whether a 150-mm-Hg P/F threshold within the range of moderate ARDS (100-200 mm Hg) would define two subgroups that were more homogeneous; and 2) which criteria led the clinicians to apply extracorporeal membrane oxygenation (ECMO) in severe ARDS. Methods: At the 150-mm-Hg P/F threshold, moderate patients were split into mild-moderate (n = 50) and moderate-severe (n = 55) groups. Patients with severe ARDS (FIO2not available in three patients) were split into higher (n = 63) and lower (n = 18) FIO2groups at an 80% FIO2threshold. Measurements and Main Results: Compared with mild- moderate ARDS, patients with moderate-severe ARDS had higher peak pressures, PaCO2, and pH. They also had heavier lungs, greater inhomogeneity, more noninflated tissue, and greater lung recruitability. Within 84 patients with severe ARDS (P/F,100 mm Hg), 75% belonged to the higher FIO2subgroup. They differed from the patients with severe ARDS with lower FIO2only in PaCO2and lung weight. Forty-one of 46 patients treated with ECMO belonged to the higher FIO2group. Within this group, the patients receiving ECMO had higher PaCO2than the 22 non-ECMO patients. The inhomogeneity ratio, total lung weight, and noninflated tissue were also significantly higher. Conclusions: Using the 150-mm-Hg P/F threshold gave a more homogeneous distribution of patients with ARDS across the severity subgroups and identified two populations that differed in their anatomical and physiological characteristics. The patients treated with ECMO belonged to the severe ARDS group, and almost 90% of them belonged to the higher FIO2subgroup
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