PURPOSE: The aim of this study was to evaluate, using a rabbit model, the little-known effect of different levels of peak inspiratory flow on acutely injured lungs. METHODS: Fourteen male rabbits (body weight, 2,711 +/- 146 g) were anesthetized and their lungs were injured by alveolar overstretch with mechanical ventilation until Pa(O(2)) was reduced below 300 mmHg. Injured animals were randomly assigned to: the P group-to receive pressure-regulated volume-control ventilation (PRVCV; n = 7); and the V group-to receive volume-control ventilation (VCV; n = 7). Other ventilator settings were: fraction of inspired oxygen (FI(O(2)), 1.0; tidal volume, 20 ml x kg(-1); positive end-expiratory pressure (PEEP) 5 cmH(2)O; and respiratory rate, 20 min(-1). The animals were thus ventilated for 4 h. Throughout the protocol, ventilatory parameters and blood gas were measured every 30 min. After the protocol, the lung wet-to-dry ratio and histological lung injury score were evaluated in the excised lungs. RESULTS: Throughout the protocol, peak inspiratory flow and mean inspiratory flow values in the P group were significantly higher than those in the V group (26.7 +/- 5.0 l x min(-1) vs 1.2 +/- 0.2 l x min(-1), and 4.3 +/- 0.3 l x min(-1) vs 1.1 +/- 0.1 l x min(-1); P < 0.05). The wet-to-dry ratio in the P group was also significantly higher than that in the V group (7.7 +/- 0.9 vs 6.3 +/- 0.5; P < 0.05). More animals in the P group than in the V group had end-of-protocol Pa(O(2))/FI(O(2)) ratios below 200 mmHg (43% vs 0%; P = 0.06). CONCLUSION: In rabbits with injured lungs, high peak inspiratory flow with high tidal volume (V(T)) reduces the Pa(O(2))/FI(O(2)) ratio and increases the lung wet-to-dry ratio.
PURPOSE: The aim of this study was to evaluate, using a rabbit model, the little-known effect of different levels of peak inspiratory flow on acutely injured lungs. METHODS: Fourteen male rabbits (body weight, 2,711 +/- 146 g) were anesthetized and their lungs were injured by alveolar overstretch with mechanical ventilation until Pa(O(2)) was reduced below 300 mmHg. Injured animals were randomly assigned to: the P group-to receive pressure-regulated volume-control ventilation (PRVCV; n = 7); and the V group-to receive volume-control ventilation (VCV; n = 7). Other ventilator settings were: fraction of inspired oxygen (FI(O(2)), 1.0; tidal volume, 20 ml x kg(-1); positive end-expiratory pressure (PEEP) 5 cmH(2)O; and respiratory rate, 20 min(-1). The animals were thus ventilated for 4 h. Throughout the protocol, ventilatory parameters and blood gas were measured every 30 min. After the protocol, the lung wet-to-dry ratio and histological lung injury score were evaluated in the excised lungs. RESULTS: Throughout the protocol, peak inspiratory flow and mean inspiratory flow values in the P group were significantly higher than those in the V group (26.7 +/- 5.0 l x min(-1) vs 1.2 +/- 0.2 l x min(-1), and 4.3 +/- 0.3 l x min(-1) vs 1.1 +/- 0.1 l x min(-1); P < 0.05). The wet-to-dry ratio in the P group was also significantly higher than that in the V group (7.7 +/- 0.9 vs 6.3 +/- 0.5; P < 0.05). More animals in the P group than in the V group had end-of-protocol Pa(O(2))/FI(O(2)) ratios below 200 mmHg (43% vs 0%; P = 0.06). CONCLUSION: In rabbits with injured lungs, high peak inspiratory flow with high tidal volume (V(T)) reduces the Pa(O(2))/FI(O(2)) ratio and increases the lung wet-to-dry ratio.
Authors: M B Amato; C S Barbas; D M Medeiros; R B Magaldi; G P Schettino; G Lorenzi-Filho; R A Kairalla; D Deheinzelin; C Munoz; R Oliveira; T Y Takagaki; C R Carvalho Journal: N Engl J Med Date: 1998-02-05 Impact factor: 91.245
Authors: Roy G Brower; Michael A Matthay; Alan Morris; David Schoenfeld; B Taylor Thompson; Arthur Wheeler Journal: N Engl J Med Date: 2000-05-04 Impact factor: 91.245
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