SUSIMEIRE GOMES
Projetos de Pesquisa
Unidades Organizacionais
LIM/09 - Laboratório de Pneumologia, Hospital das Clínicas, Faculdade de Medicina
5 resultados
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- 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.
- High Positive End-Expiratory Pressure Renders Spontaneous Effort Noninjurious(2018) MORAIS, Caio C. A.; KOYAMA, Yukiko; YOSHIDA, Takeshi; PLENS, Glauco M.; GOMES, Susimeire; LIMA, Cristhiano A. S.; RAMOS, Ozires P. S.; PEREIRA, Sergio M.; KAWAGUCHI, Naomasa; YAMAMOTO, Hirofumi; UCHIYAMA, Akinori; BORGES, Joao B.; MELO, Marcos F. Vidal; TUCCI, Mauro R.; AMATO, Marcelo B. P.; KAVANAGH, Brian P.; COSTA, Eduardo L. V.; FUJINO, YujiRationale: In acute respiratory distress syndrome (ARDS), atelectatic solid-like lung tissue impairs transmission of negative swings in pleural pressure (Ppl) that result from diaphragmatic contraction. The localization of more negative Ppl proportionally increases dependent lung stretch by drawing gas either from other lung regions (e.g., nondependent lung [pendelluft]) or from the ventilator. Lowering the level of spontaneous effort and/or converting solid-like to fluid-like lung might render spontaneous effort noninjurious. Objectives: To determine whether spontaneous effort increases dependent lung injury, and whether such injury would be reduced by recruiting atelectatic solid-like lung with positive end-expiratory pressure (PEEP). Methods: Established models of severe ARDS (rabbit, pig) were used. Regional histology (rabbit), inflammation (positron emission tomography; pig), regional inspiratory Ppl (intrabronchial balloon manometry), and stretch (electrical impedance tomography; pig) were measured. Respiratory drive was evaluated in 11 patients with ARDS. Measurements and Main Results: Although injury during muscle paralysis was predominantly in nondependent and middle lung regions at low (vs. high) PEEP, strong inspiratory effort increased injury (indicated by positron emission tomography and histology) in dependent lung. Stronger effort (vs. muscle paralysis) caused local overstretch and greater tidal recruitment in dependent lung, where more negative Ppl was localized and greater stretch was generated. In contrast, high PEEP minimized lung injury by more uniformly distributing negative Ppl, and lowering the magnitude of spontaneous effort (i.e., deflection in esophageal pressure observed in rabbits, pigs, and patients). Conclusions: Strong effort increased dependent lung injury, where higher local lung stress and stretch was generated; effort-dependent lung injury was minimized by high PEEP in severe ARDS, which may offset need for paralysis.
conferenceObject Spontaneous Breathing During Mechanical Ventilation Causes Unsuspected Over-Inflation Of Dependent Lung(2013) YOSHIDA, T.; TORSANI, V.; GOMES, S.; SANTIAGO, R. R. S.; CARVALHO, C. R. R.; KAVANAGH, B. P.; AMATO, M. B. P.- 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.
- Spontaneous Effort Causes Occult Pendelluft during Mechanical Ventilation(2013) YOSHIDA, Takeshi; TORSANI, Vinicius; GOMES, Susimeire; SANTIS, Roberta R. De; BERALDO, Marcelo A.; COSTA, Eduardo L. V.; TUCCI, Mauro R.; ZIN, Walter A.; KAVANAGH, Brian P.; AMATO, Marcelo B. P.Rationale: In normal lungs, local changes in pleural pressure (P-pl) are generalized over the whole pleural surface. However, in a patient with injured lungs, we observed (using electrical impedance tomography) a pendelluft phenomenon (movement of air within the lung from nondependent to dependent regions without change in tidal volume) that was caused by spontaneous breathing during mechanical ventilation. Objectives: To test the hypotheses that in injured lungs negative P-pl generated by diaphragm contraction has localized effects (in dependent regions) that are not uniformly transmitted, and that such localized changes in P-pl cause pendelluft. Methods: We used electrical impedance tomography and dynamic computed tomography (CT) to analyze regional inflation in anesthetized pigs with lung injury. Changes in local P-pl were measured in nondependent versus dependent regions using intrabronchial balloon catheters. The airway pressure needed to achieve comparable dependent lung inflation during paralysis versus spontaneous breathing was estimated. Measurements and Main Results: In all animals, spontaneous breathing caused pendelluft during early inflation, which was associated with more negative local P-pl in dependent regions versus nondependent regions (-13.0 +/- 4.0 vs. -6.4 +/- 3.8 cm H2O; P < 0.05). Dynamic CT confirmed pendelluft, which occurred despite limitation of tidal volume to less than 6 ml/kg. Comparable inflation of dependent lung during paralysis required almost threefold greater driving pressure (and tidal volume) versus spontaneous breathing (28.0 +/- 0.5 vs. 10.3 +/- 0.6 cm H2O, P < 0.01; 14.8 +/- 4.6 vs. 5.8 +/- 1.6 ml/kg, P < 0.05). Conclusions: Spontaneous breathing effort during mechanical ventilation causes unsuspected overstretch of dependent lung during early inflation (associated with reciprocal deflation of nondependent lung). Even when not increasing tidal volume, strong spontaneous effort may potentially enhance lung damage.