VINICIUS TORSANI
Projetos de Pesquisa
Unidades Organizacionais
Instituto Central, Hospital das Clínicas, Faculdade de Medicina
4 resultados
Resultados de Busca
Agora exibindo 1 - 4 de 4
- Spontaneous Effort During Mechanical Ventilation: Maximal Injury With Less Positive End-Expiratory Pressure(2016) YOSHIDA, Takeshi; ROLDAN, Rollin; BERALDO, Marcelo A.; TORSANI, Vinicius; GOMES, Susimeire; SANTIS, Roberta R. De; COSTA, Eduardo L. V.; TUCCI, Mauro R.; LIMA, Raul G.; KAVANAGH, Brian P.; AMATO, Marcelo B. P.Objectives: We recently described how spontaneous effort during mechanical ventilation can cause ""pendelluft,"" that is, displacement of gas from nondependent (more recruited) lung to dependent (less recruited) lung during early inspiration. Such transfer depends on the coexistence of more recruited (source) liquid-like lung regions together with less recruited (target) solid-like lung regions. Pendelluft may improve gas exchange, but because of tidal recruitment, it may also contribute to injury. We hypothesize that higher positive end-expiratory pressure levels decrease the propensity to pendelluft and that with lower positive end-expiratory pressure levels, pendelluft is associated with improved gas exchange but increased tidal recruitment. Design: Crossover design. Setting: University animal research laboratory. Subjects: Anesthetized landrace pigs. Interventions: Surfactant depletion was achieved by saline lavage in anesthetized pigs, and ventilator-induced lung injury was produced by ventilation with high tidal volume and low positive end-expiratory pressure. Ventilation was continued in each of four conditions: positive end-expiratory pressure (low or optimized positive end-expiratory pressure after recruitment) and spontaneous breathing (present or absent). Tidal recruitment was assessed using dynamic CT and regional ventilation/perfusion using electric impedance tomography. Esophageal pressure was measured using an esophageal balloon manometer. Measurements and Results: Among the four conditions, spontaneous breathing at low positive end-expiratory pressure not only caused the largest degree of pendelluft, which was associated with improved ventilation/perfusion matching and oxygenation, but also generated the greatest tidal recruitment. At low positive end-expiratory pressure, paralysis worsened oxygenation but reduced tidal recruitment. Optimized positive end-expiratory pressure decreased the magnitude of spontaneous efforts (measured by esophageal pressure) despite using less sedation, from -5.6 +/- 1.3 to -2.0 +/- 0.7 cm H2O, while concomitantly reducing pendelluft and tidal recruitment. No pendelluft was observed in the absence of spontaneous effort. Conclusions: Spontaneous effort at low positive end-expiratory pressure improved oxygenation but promoted tidal recruitment associated with pendelluft. Optimized positive end-expiratory pressure (set after lung recruitment) may reverse the harmful effects of spontaneous breathing by reducing inspiratory effort, pendelluft, and tidal recruitment.
- Transpulmonary Pressure Describes Lung Morphology During Decremental Positive End-Expiratory Pressure Trials in Obesity(2017) FUMAGALLI, Jacopo; BERRA, Lorenzo; ZHANG, Changsheng; PIRRONE, Massimiliano; SANTIAGO, Roberta R. De Santis; GOMES, Susimeire; MAGNI, Federico; SANTOS, Glaucia A. B. dos; BENNETT, Desmond; TORSANI, Vinicius; FISHER, Daniel; MORAIS, Caio; AMATO, Marcelo B. P.; KACMAREK, Robert M.Objectives: Atelectasis develops in critically ill obese patients when undergoing mechanical ventilation due to increased pleural pressure. The current study aimed to determine the relationship between transpulmonary pressure, lung mechanics, and lung morphology and to quantify the benefits of a decremental positive end-expiratory pressure trial preceded by a recruitment maneuver. Design: Prospective, crossover, nonrandomized interventional study. Setting: Medical and Surgical Intensive Care Units at Massachusetts General Hospital (Boston, MA) and University Animal Research Laboratory (Sao Paulo, Brazil). Patients/Subjects: Critically ill obese patients with acute respiratory failure and anesthetized swine. Interventions: Clinical data from 16 mechanically ventilated critically ill obese patients were analyzed. An animal model of obesity with reversible atelectasis was developed by placing fluid filled bags on the abdomen to describe changes of lung mechanics, lung morphology, and pulmonary hemodynamics in 10 swine. Measurements and Main Results: In obese patients (body mass index, 48 +/- 11 kg/m(2)), 21.7 +/- 3.7 cm H2O of positive end-expiratory pressure resulted in the lowest elastance of the respiratory system (18.6 +/- 6.1 cm H2O/L) after a recruitment maneuver and decremental positive end-expiratory pressure and corresponded to a positive (2.1 +/- 2.2 cm H2O) end-expiratory transpulmonary pressure. Ventilation at lowest elastance positive end-expiratory pressure preceded by a recruitment maneuver restored end-expiratory lung volume (30.4 +/- 9.1 mL/kg ideal body weight) and oxygenation (273.4 +/- 72.1 mm Hg). In the swine model, lung collapse and intratidal recruitment/derecruitment occurred when the positive end-expiratory transpulmonary pressure decreased below 2-4 cm H2O. After the development of atelectasis, a decremental positive end-expiratory pressure trial preceded by lung recruitment identified the positive end-expiratory pressure level (17.4 +/- 2.1 cm H2O) needed to restore poorly and nonaerated lung tissue, reestablishing lung elastance and oxygenation while avoiding increased pulmonary vascular resistance. Conclusions: In obesity, low-to-negative values of transpulmonary pressure predict lung collapse and intratidal recruitment/derecruitment. A decremental positive end-expiratory pressure trial preceded by a recruitment maneuver reverses atelectasis, improves lung mechanics, distribution of ventilation and oxygenation, and does not increase pulmonary vascular resistance.
- Volume-controlled Ventilation Does Not Prevent Injurious Inflation during Spontaneous Effort(2017) YOSHIDA, Takeshi; NAKAHASHI, Susumu; NAKAMURA, Maria Aparecida Miyuki; KOYAMA, Yukiko; ROLDAN, Rollin; TORSANI, Vinicius; SANTIS, Roberta R. De; GOMES, Susimeire; UCHIYAMA, Akinori; AMATO, Marcelo B. P.; KAVANAGH, Brian P.; FUJINO, YujiRationale: Spontaneous breathing during mechanical ventilation increases transpulmonary pressure and VT, and worsens lung injury. Intuitively, controlling VT and transpulmonary pressure might limit injury caused by added spontaneous effort. Objectives: To test the hypothesis that, during spontaneous effort in injured lungs, limitation of VT and transpulmonary pressure by volume-controlled ventilation results in less injurious patterns of inflation. Methods: Dynamic computed tomography was used to determine patterns of regional inflation in rabbits with injured lungs during volume-controlled or pressure-controlled ventilation. Transpulmonary pressure was estimated by using esophageal balloon manometry [PL(es)] with and without spontaneous effort. Local dependent lung stress was estimated as the swing (inspiratory change) in transpulmonary pressure measured by intrapleural manometry in dependent lung and was compared with the swing in PL(es). Electrical impedance tomography was performed to evaluate the inflation pattern in a larger animal (pig) and in a patient with acute respiratory distress syndrome. Measurements and Main Results: Spontaneous breathing in injured lungs increased PL(es) during pressure-controlled (but not volume-controlled) ventilation, but the pattern of dependent lung inflation was the same in both modes. In volume-controlled ventilation, spontaneous effort caused greater inflation and tidal recruitment of dorsal regions (greater than twofold) compared with during muscle paralysis, despite the same VT and PL(es). This was caused by higher local dependent lung stress (measured by intrapleural manometry). In injured lungs, esophageal manometry underestimated local dependent pleural pressure changes during spontaneous effort. Conclusions: Limitation of VT and PL(es) by volume-controlled ventilation could not eliminate harm caused by spontaneous breathing unless the level of spontaneous effort was lowered and local dependent lung stress was reduced.
- Quantitative Dual-Energy Computed Tomography Predicts Regional Perfusion Heterogeneity in a Model of Acute Lung Injury(2018) KAY, Fernando Uliana; BERALDO, Marcelo A.; NAKAMURA, Maria A. M.; SANTIAGO, Roberta De Santis; TORSANI, Vinicius; GOMES, Susimeire; ROLDAN, Rollin; TUCCI, Mauro R.; ABBARA, Suhny; AMATO, Marcelo B. P.; AMARO JR., EdsonObjective The aims of this study were to investigate the ability of contrast-enhanced dual-energy computed tomography (DECT) for assessing regional perfusion in a model of acute lung injury, using dynamic first-pass perfusion CT (DynCT) as the criterion standard and to evaluate if changes in lung perfusion caused by prone ventilation are similarly demonstrated by DECT and DynCT. Methods This was an institutional review board-approved study, compliant with guidelines for humane care of laboratory animals. A ventilator-induced lung injury protocol was applied to 6 landrace pigs. Perfused blood volume (PBV) and pulmonary blood flow (PBF) were respectively quantified by DECT and DynCT, in supine and prone positions. The lungs were segmented in equally sized regions of interest, namely, dorsal, middle, and ventral. Perfused blood volume and PBF values were normalized by lung density. Regional air fraction (AF) was assessed by triple-material decomposition DECT. Per-animal correlation between PBV and PBF was assessed with Pearson R. Regional differences in PBV, PBF, and AF were evaluated with 1-way analysis of variance and post hoc linear trend analysis ( = 5%). Results Mean correlation coefficient between PBV and PBF was 0.70 (range, 0.55-0.98). Higher PBV and PBF values were observed in dorsal versus ventral regions. Dorsal-to-ventral linear trend slopes were -10.24 mL/100 g per zone for PBV (P < 0.001) and -223.0 mL/100 g per minute per zone for PBF (P < 0.001). Prone ventilation also revealed higher PBV and PBF in dorsal versus ventral regions. Dorsal-to-ventral linear trend slopes were -16.16 mL/100 g per zone for PBV (P < 0.001) and -108.2 mL/100 g per minute per zone for PBF (P < 0.001). By contrast, AF was lower in dorsal versus ventral regions in supine position, with dorsal-to-ventral linear trend slope of +5.77%/zone (P < 0.05). Prone ventilation was associated with homogenization of AF distribution among different regions (P = 0.74). Conclusions Dual-energy computed tomography PBV is correlated with DynCT-PBF in a model of acute lung injury, and able to demonstrate regional differences in pulmonary perfusion. Perfusion was higher in the dorsal regions, irrespectively to decubitus, with more homogeneous lung aeration in prone position.