OBJECTIVE: Uncertainties about the numerous degrees of freedom in ventilator settings leave many unanswered questions about the biophysical determinants of lung injury. We investigated whether mechanical ventilation with high air flow could yield lung mechanical stress even in normal animals. DESIGN: Prospective, randomized, controlled experimental study. SETTING: University research laboratory. SUBJECTS: Thirty normal male Wistar rats (180-230 g). INTERVENTIONS: Rats were ventilated for 2 hrs with tidal volume of 10 mL/kg and either with normal inspiratory air flow (V') of 10 mL/s (F10) or high V' of 30 mL/s (F30). In the control group, animals did not undergo mechanical ventilation. Because high flow led to elevated respiratory rate (200 breaths/min) and airway peak inspiratory pressure (PIP,aw = 17 cm H2O), two additional groups were established to rule out the potential contribution of these variables: a) normal respiratory rate = 100 breaths/min and V' = 30 mL/sec; and b) PIP,aw = 17 cm H2O and V' = 10 mL/sec. MEASUREMENTS AND MAIN RESULTS: Lung mechanics and histology (light and electron microscopy), arterial blood gas analysis, and type III procollagen messenger RNA expression in lung tissue were analyzed. Ultrastructural microscopy was similar in control and F10 groups. High air flow led to increased lung plateau and peak pressures, hypoxemia, alveolar hyperinflation and collapse, pulmonary neutrophilic infiltration, and augmented type III procollagen messenger RNA expression compared with control rats. The reduction of respiratory rate did not modify the morphofunctional behavior observed in the presence of increased air flow. Even though the increase in peak pressure yielded mechanical and histologic changes, type III procollagen messenger RNA expression remained unaltered. CONCLUSIONS: Ventilation with high inspiratory air flow may lead to high tensile and shear stresses resulting in lung functional and morphologic compromise and elevation of type III procollagen messenger RNA expression.
OBJECTIVE: Uncertainties about the numerous degrees of freedom in ventilator settings leave many unanswered questions about the biophysical determinants of lung injury. We investigated whether mechanical ventilation with high air flow could yield lung mechanical stress even in normal animals. DESIGN: Prospective, randomized, controlled experimental study. SETTING: University research laboratory. SUBJECTS: Thirty normal male Wistar rats (180-230 g). INTERVENTIONS:Rats were ventilated for 2 hrs with tidal volume of 10 mL/kg and either with normal inspiratory air flow (V') of 10 mL/s (F10) or high V' of 30 mL/s (F30). In the control group, animals did not undergo mechanical ventilation. Because high flow led to elevated respiratory rate (200 breaths/min) and airway peak inspiratory pressure (PIP,aw = 17 cm H2O), two additional groups were established to rule out the potential contribution of these variables: a) normal respiratory rate = 100 breaths/min and V' = 30 mL/sec; and b) PIP,aw = 17 cm H2O and V' = 10 mL/sec. MEASUREMENTS AND MAIN RESULTS: Lung mechanics and histology (light and electron microscopy), arterial blood gas analysis, and type III procollagen messenger RNA expression in lung tissue were analyzed. Ultrastructural microscopy was similar in control and F10 groups. High air flow led to increased lung plateau and peak pressures, hypoxemia, alveolar hyperinflation and collapse, pulmonary neutrophilic infiltration, and augmented type III procollagen messenger RNA expression compared with control rats. The reduction of respiratory rate did not modify the morphofunctional behavior observed in the presence of increased air flow. Even though the increase in peak pressure yielded mechanical and histologic changes, type III procollagen messenger RNA expression remained unaltered. CONCLUSIONS: Ventilation with high inspiratory air flow may lead to high tensile and shear stresses resulting in lung functional and morphologic compromise and elevation of type III procollagen messenger RNA expression.
Authors: Felipe Saddy; Gisele P Oliveira; Cristiane S N B Garcia; Liliane M Nardelli; Andreia F Rzezinski; Debora S Ornellas; Marcelo M Morales; Vera L Capelozzi; Paolo Pelosi; Patricia R M Rocco Journal: Intensive Care Med Date: 2010-03-24 Impact factor: 17.440
Authors: Paula W Steimback; Gisele P Oliveira; Andréia F Rzezinski; Pedro L Silva; Cristiane S N B Garcia; Graziela Rangel; Marcelo M Morales; José R Lapa E Silva; Vera L Capelozzi; Paolo Pelosi; Patricia R M Rocco Journal: Intensive Care Med Date: 2009-02-17 Impact factor: 17.440
Authors: Cíntia L Santos; Lillian Moraes; Raquel S Santos; Mariana G Oliveira; Johnatas D Silva; Tatiana Maron-Gutierrez; Débora S Ornellas; Marcelo M Morales; Vera L Capelozzi; Nelson Jamel; Paolo Pelosi; Patricia R M Rocco; Cristiane S N B Garcia Journal: Intensive Care Med Date: 2012-01-11 Impact factor: 17.440
Authors: Robin Paudel; Christine A Trinkle; Christopher M Waters; Lauren E Robinson; Evan Cassity; Jamie L Sturgill; Richard Broaddus; Peter E Morris Journal: Am J Med Sci Date: 2021-09-28 Impact factor: 2.378
Authors: Jérôme Allardet-Servent; Matthias Castanier; Thomas Signouret; Rettinavelou Soundaravelou; Anne Lepidi; Jean-Marie Seghboyan Journal: Crit Care Med Date: 2015-12 Impact factor: 7.598