Sustained inflation and incremental mean airway pressure trial during conventional and high-frequency oscillatory ventilation in a large porcine model of acute respiratory distress syndrome (original) (raw)
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Clinics, 2008
Rossi FS, Mascaretti RS, Haddad LB, Freddi NA, Mauad T, Rebello CM. Utilization of the lower inflection point of the pressure-volume curve results in protective conventional ventilation comparable to high frequency oscillatory ventilation in an animal model of acute respiratory distress syndrome. Clinics. 2008;63:237-44. INTRODUCTION: Studies comparing high frequency oscillatory and conventional ventilation in acute respiratory distress syndrome have used low values of positive end-expiratory pressure and identified a need for better recruitment and pulmonary stability with high frequency. OBJECTIVE: To compare conventional and high frequency ventilation using the lower inflection point of the pressure-volume curve as the determinant of positive end-expiratory pressure to obtain similar levels of recruitment and alveolar stability. METHODS: After lung lavage of adult rabbits and lower inflection point determination, two groups were randomized: conventional (positive end-expiratory pressure = lower inflection point; tidal volume=6 ml/kg) and high frequency ventilation (mean airway pressures= lower inflection point +4 cmH 2 O). Blood gas and hemodynamic data were recorded over 4 h. After sacrifice, protein analysis from lung lavage and histologic evaluation were performed. RESULTS: The oxygenation parameters, protein and histological data were similar, except for the fact that significantly more normal alveoli were observed upon protective ventilation. High frequency ventilation led to lower PaCO 2 levels. DISCUSSION: Determination of the lower inflection point of the pressure-volume curve is important for setting the minimum end expiratory pressure needed to keep the airways opened. This is useful when comparing different strategies to treat severe respiratory insufficiency, optimizing conventional ventilation, improving oxygenation and reducing lung injury. CONCLUSIONS: Utilization of the lower inflection point of the pressure-volume curve in the ventilation strategies considered in this study resulted in comparable efficacy with regards to oxygenation and hemodynamics, a high PaCO 2 level and a lower pH. In addition, a greater number of normal alveoli were found after protective conventional ventilation in an animal model of acute respiratory distress syndrome.
Critical care (London, England), 2018
Recent clinical studies have not shown an overall benefit of high-frequency oscillatory ventilation (HFOV), possibly due to injurious or non-individualized HFOV settings. We compared conventional HFOV (HFOV) settings with HFOV settings based on mean transpulmonary pressures (P) in an animal model of experimental acute respiratory distress syndrome (ARDS). ARDS was induced in eight pigs by intrabronchial installation of hydrochloric acid (0.1 N, pH 1.1; 2.5 ml/kg body weight). The animals were initially ventilated in volume-controlled mode with low tidal volumes (6 ml kg) at three positive end-expiratory pressure (PEEP) levels (5, 10, 20 cmHO) followed by HFOV and then HFOV P each at PEEP 10 and 20. The continuous distending pressure (CDP) during HFOV was set at mean airway pressure plus 5 cmHO. For HFOV P it was set at mean P plus 5 cmHO. Baseline measurements were obtained before and after induction of ARDS under volume controlled ventilation with PEEP 5. The same measurements and ...
Journal of Surgical Research, 2006
Materials and methods. Experimental study, using mixed-breed pigs. Animals were assigned to one of the following groups: Control Group (CG) (n ؍ 5), applying mechanical ventilation with tidal volume (V t ) of 10 ml/kg, respiratory rate (RR) of 18 bpm, and FiO 2 of 1 for 240 min; High V t for 30 min (HVt-30) Group (n ؍ 5), applying ventilation with V t of 50 ml/kg and RR of 8 bpm and FiO 2 of 1 for 30 min, followed by ventilation as in the CG for a further 210 min; and HVt-240 Group (n ؍ 5), applying ventilation with V t of 50 ml/kg, RR of 8 bpm, and FiO 2 of 1 for 240 min. Hemodynamic parameters, airway pressures, arterial blood gases, extravascular lung water (EVLW), and cytokines (IL-2, IL-4, IL-6, IL-10, TNF-␣, and ITF-␥) in plasma and bronchoalveolar lavage (BAL) were determined. Lungs were fixed with 10% formalin for histological analysis. Results are expressed as mean ؎ standard deviation. The ANOVA test was used to compare measurements among the three groups.
Anesthesiology, 2003
Background Pressure control ventilation (PCV), high-frequency oscillation (HFO), and intratracheal pulmonary ventilation (ITPV) may all be used to provide lung protective ventilation in acute respiratory distress syndrome, but the specific approach that is optimal remains controversial. Methods Saline lavage was used to produce acute respiratory distress syndrome in 21 sheep randomly assigned to receive PCV, HFO, or ITPV as follows: positive end-expiratory pressure (PCV and ITPV) and mean airway pressure (HFO) were set in a pressure-decreasing manner after lung recruitment that achieved a ratio of Pao2/Fio2 > 400 mmHg. Respiratory rates were 30 breaths/min, 120 breaths/min, and 8 Hz, respectively, for PCV, ITPV, and HFO. Eucapnia was targeted with peak carinal pressure of no more than 35 cm H2O. Animals were then ventilated for 4 h. Results There were no differences among groups in gas exchange, lung mechanics, or hemodynamics. Tidal volume (PCV, 8.9 +/- 2.1 ml/kg; ITPV, 2.7 +/- ...
PloS one, 2017
To investigate whether performing alveolar recruitment or adding inspiratory pauses could promote physiologic benefits (VT) during moderately-high-frequency positive pressure ventilation (MHFPPV) delivered by a conventional ventilator in a porcine model of severe acute respiratory distress syndrome (ARDS). Prospective experimental laboratory study with eight pigs. Induction of acute lung injury with sequential pulmonary lavages and injurious ventilation was initially performed. Then, animals were ventilated on a conventional mechanical ventilator with a respiratory rate (RR) = 60 breaths/minute and PEEP titrated according to ARDS Network table. The first two steps consisted of a randomized order of inspiratory pauses of 10 and 30% of inspiratory time. In final step, we removed the inspiratory pause and titrated PEEP, after lung recruitment, with the aid of electrical impedance tomography. At each step, PaCO2 was allowed to stabilize between 57-63 mmHg for 30 minutes. The step with R...
Respiratory research, 2004
Biologically variable ventilation (return of physiological variability in rate and tidal volume using a computer-controller) was compared to control mode ventilation with and without a recruitment manoeuvre - 40 cm H2O for 40 sec performed hourly; in a porcine oleic acid acute lung injury model. We compared gas exchange, respiratory mechanics, and measured bronchoalveolar fluid for inflammatory cytokines, cell counts and surfactant function. Lung injury was scored by light microscopy. Pigs received mechanical ventilation (FIO2 = 0.3; PEEP 5 cm H2O) in control mode until PaO2 decreased to 60 mm Hg with oleic acid infusion (PaO2/FIO2 <200 mm Hg). Additional PEEP to 10 cm H2O was added after injury. Animals were randomized to one of the 3 modes of ventilation and followed for 5 hr after injury. PaO2 and respiratory system compliance was significantly greater with biologically variable ventilation compared to the other 2 groups. Mean and mean peak airway pressures were also lower. Th...
Journal of Clinical Medicine, 2021
The effects of a moderately elevated intra-abdominal pressure (IAP) on lung mechanics in acute respiratory distress syndrome (ARDS) have still not been fully analyzed. Moreover, the optimal positive end-expiratory pressure (PEEP) in elevated IAP and ARDS is unclear. In this paper, 18 pigs under general anesthesia received a double hit lung injury. After saline lung lavage and 2 h of injurious mechanical ventilation to induce an acute lung injury (ALI), an intra-abdominal balloon was filled until an IAP of 10 mmHg was generated. Animals were randomly assigned to one of three groups (group A = PEEP 5, B = PEEP 10 and C = PEEP 15 cmH2O) and ventilated for 6 h. We measured end-expiratory lung volume (EELV) per kg bodyweight, driving pressure (ΔP), transpulmonary pressure (ΔPL), static lung compliance (Cstat), oxygenation (P/F ratio) and cardiac index (CI). In group A, we found increases in ΔP (22 ± 1 vs. 28 ± 2 cmH2O; p = 0.006) and ΔPL (16 ± 1 vs. 22 ± 2 cmH2O; p = 0.007), with no chan...