scholarly journals Effects of Various Modes of Mechanical Ventilation in Normal Rats

2014 ◽  
Vol 120 (4) ◽  
pp. 943-950 ◽  
Author(s):  
Matteo Pecchiari ◽  
Ario Monaco ◽  
Antonia Koutsoukou ◽  
Patrizia Della Valle ◽  
Guendalina Gentile ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
Inflammatory Response ◽  
Negative Pressure ◽  
Positive Pressure Ventilation ◽  
Lung Mechanics ◽  
Whole Body ◽  
Positive Pressure ◽  
Negative Pressure Ventilation ◽  
Cytokine Levels

Abstract Background: Recent studies in healthy mice and rats have reported that positive pressure ventilation delivered with physiological tidal volumes at normal end-expiratory volume worsens lung mechanics and induces cytokine release, thus suggesting that detrimental effects are due to positive pressure ventilation per se. The aim of this study in healthy animals is to assess whether these adverse outcomes depend on the mode of mechanical ventilation. Methods: Rats were subjected to 4 h of spontaneous, positive pressure, and whole-body or thorax-only negative pressure ventilation (N = 8 per group). In all instances the ventilatory pattern was that of spontaneous breathing. Lung mechanics, cytokines concentration in serum and broncho–alveolar lavage fluid, lung wet-to-dry ratio, and histology were assessed. Values from eight animals euthanized shortly after anesthesia served as control. Results: No evidence of mechanical ventilation–dependent lung injury was found in terms of lung mechanics, histology, or wet-to-dry ratio. Relative to control, cytokine levels and recruitment of polymorphonuclear leucocytes increased slightly, and to the same extent with spontaneous, positive pressure, and whole-body negative pressure ventilation. Thorax-only negative pressure ventilation caused marked chest and lung distortion, reversible increase of lung elastance, and higher polymorphonuclear leucocyte count and cytokine levels. Conclusion: Both positive and negative pressure ventilation performed with tidal volumes and timing of spontaneous, quiet breathing neither elicit an inflammatory response nor cause morpho-functional alterations in normal animals, thus supporting the notion of the presence of a critical volume threshold above which acute lung injury ensues. Distortion of lung parenchyma can induce an inflammatory response, even in the absence of volotrauma.

Negative Pressure Ventilation and Positive Pressure Ventilation Promote Comparable Levels of Ventilator-induced Diaphragmatic Dysfunction in Rats

2013 ◽  
Vol 119 (3) ◽  
pp. 652-662 ◽  
Author(s):  
Christian S. Bruells ◽  
Ashley J. Smuder ◽  
Lucy K. Reiss ◽  
Matthew B. Hudson ◽  
William Bradley Nelson ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Negative Pressure ◽  
Positive Pressure Ventilation ◽  
Cross Sectional Area ◽  
Contractile Properties ◽  
Positive Pressure ◽  
Sectional Area ◽  
Diaphragmatic Dysfunction ◽  
Cross Sectional ◽  
Negative Pressure Ventilation

Abstract Background: Mechanical ventilation is a life-saving intervention for patients with respiratory failure. Unfortunately, a major complication associated with prolonged mechanical ventilation is ventilator-induced diaphragmatic atrophy and contractile dysfunction, termed ventilator-induced diaphragmatic dysfunction (VIDD). Emerging evidence suggests that positive pressure ventilation (PPV) promotes lung damage (ventilator-induced lung injury [VILI]), resulting in the release of signaling molecules that foster atrophic signaling in the diaphragm and the resultant VIDD. Although a recent report suggests that negative pressure ventilation (NPV) results in less VILI than PPV, it is unknown whether NPV can protect against VIDD. Therefore, the authors tested the hypothesis that compared with PPV, NPV will result in a lower level of VIDD. Methods: Adult rats were randomly assigned to one of three experimental groups (n = 8 each): (1) acutely anesthetized control (CON), (2) 12 h of PPV, and (3) 12 h of NPV. Dependent measures included indices of VILI, diaphragmatic muscle fiber cross-sectional area, diaphragm contractile properties, and the activity of key proteases in the diaphragm. Results: Our results reveal that no differences existed in the degree of VILI between PPV and NPV animals as evidenced by VILI histological scores (CON = 0.082 ± 0.001; PPV = 0.22 ± 0.04; NPV = 0.25 ± 0.02; mean ± SEM). Both PPV and NPV resulted in VIDD. Importantly, no differences existed between PPV and NPV animals in diaphragmatic fiber cross-sectional area, contractile properties, and the activation of proteases. Conclusion: These results demonstrate that NPV and PPV result in similar levels of VILI and that NPV and PPV promote comparable levels of VIDD in rats.

scholarly journals Negative pressure ventilation enhances acinar perfusion in isolated rat lungs

2017 ◽  
Vol 8 (1) ◽  
pp. 204589321775359 ◽  
Author(s):  
Kal E. Watson ◽  
Gilad S. Segal ◽  
Robert L. Conhaim
Keyword(s):  
Negative Pressure ◽  
Pulmonary Circulation ◽  
Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Latex Particles ◽  
Negative Pressure Ventilation ◽  
Rat Lungs ◽  
Confocal Images ◽  
Negative Pressures ◽  
Isolated Rat

We compared acinar perfusion in isolated rat lungs ventilated using positive or negative pressures. The lungs were ventilated with air at transpulmomary pressures of 15/5 cm H2O, at 25 breaths/min, and perfused with a hetastarch solution at Ppulm art/PLA pressures of 10/0 cm H2O. We evaluated overall perfusability from perfusate flows, and from the venous concentrations of 4-µm diameter fluorescent latex particles infused into the pulmonary circulation during perfusion. We measured perfusion distribution from the trapping patterns of those particles within the lung. We infused approximately 9 million red fluorescent particles into each lung, followed 20 min later by an infusion of an equal number of green particles. In positive pressure lungs, 94.7 ± 2.4% of the infused particles remained trapped within the lungs, compared to 86.8 ± 5.6% in negative pressure lungs ( P ≤ 0.05). Perfusate flows averaged 2.5 ± 0.1 mL/min in lungs ventilated with positive pressures, compared to 5.6 ± 01 mL/min in lungs ventilated with negative pressures ( P ≤ 0.05). Particle infusions had little effect on perfusate flows. In confocal images of dried sections of each lung, red and green particles were co-localized in clusters in positive pressure lungs, suggesting that acinar vessels that lacked particles were collapsed by these pressures thereby preventing perfusion through them. Particles were more broadly and uniformly distributed in negative pressure lungs, suggesting that perfusion in these lungs was also more uniformly distributed. Our results suggest that the acinar circulation is organized as a web, and further suggest that portions of this web are collapsed by positive pressure ventilation.

scholarly journals Continuous external negative pressure improves oxygenation and respiratory mechanics in Experimental Lung Injury in Pigs – A pilot proof-of-concept trial

2020 ◽  
Vol 8 (S1) ◽  
Author(s):  
Martin Scharffenberg ◽  
Jakob Wittenstein ◽  
Moritz Herzog ◽  
Sebastian Tauer ◽  
Luigi Vivona ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Lung Injury ◽  
Negative Pressure ◽  
Positive Pressure Ventilation ◽  
Respiratory Mechanics ◽  
Peep Level ◽  
Pressure Sensors ◽  
Transpulmonary Pressure ◽  
Positive Pressure ◽  
Impedance Tomography

Abstract Background Continuous external negative pressure (CENP) during positive pressure ventilation can recruit dependent lung regions. We hypothesised that CENP applied regionally to the thorax or the abdomen only, increases the caudal end-expiratory transpulmonary pressure depending on positive end-expiratory pressure (PEEP) in lung-injured pigs. Eight pigs were anesthetised and mechanically ventilated in the supine position. Pressure sensors were placed in the left pleural space, and a lung injury was induced by saline lung lavages. A CENP shell was placed at the abdomen and thorax (randomised order), and animals were ventilated with PEEP 15, 7 and zero cmH2O (15 min each). On each PEEP level, CENP of − 40, − 30, − 20, − 10 and 0 cmH2O was applied (3 min each). Respiratory and haemodynamic variables were recorded. Electrical impedance tomography allowed assessment of centre of ventilation. Results Compared to positive pressure ventilation alone, the caudal transpulmonary pressure was significantly increased by CENP of ≤ 20 cmH2O at all PEEP levels. CENP of – 20 cmH2O reduced the mean airway pressure at zero PEEP (P = 0.025). The driving pressure decreased at CENP of ≤ 10 at PEEP of 0 and 7 cmH2O (P < 0.001 each) but increased at CENP of – 30 cmH2O during the highest PEEP (P = 0.001). CENP of – 30 cmH2O reduced the mechanical power during zero PEEP (P < 0.001). Both elastance (P < 0.001) and resistance (P < 0.001) were decreased at CENP ≤ 30 at PEEP of 0 and 7 cmH2O. Oxygenation increased at CENP of ≤ 20 at PEEP of 0 and 7 cmH2O (P < 0.001 each). Applying external negative pressure significantly shifted the centre of aeration towards dorsal lung regions irrespectively of the PEEP level. Cardiac output decreased significantly at CENP -20 cmH2O at all PEEP levels (P < 0.001). Effects on caudal transpulmonary pressure, elastance and cardiac output were more pronounced when CENP was applied to the abdomen compared with the thorax. Conclusions In this lung injury model in pigs, CENP increased the end-expiratory caudal transpulmonary pressure. This lead to a shift of lung aeration towards dependent zones as well as improved respiratory mechanics and oxygenation, especially when CENP was applied to the abdomen as compared to the thorax. CENP values ≤ 20 cmH2O impaired the haemodynamics.

Mechanical Ventilation Affects Lung Function and Cytokine Production in an Experimental Model of Endotoxemia

2005 ◽  
Vol 102 (2) ◽  
pp. 331-339 ◽  
Author(s):  
Fabienne Brégeon ◽  
Stéphane Delpierre ◽  
Bruno Chetaille ◽  
Osamu Kajikawa ◽  
Thomas R Martin ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
Tidal Volume ◽  
Blood Gases ◽  
Lung Mechanics ◽  
Positive Pressure ◽  
Positive End Expiratory Pressure ◽  
Cell Counts ◽  
Volume Controlled Ventilation ◽  
Spontaneously Breathing

Background Mechanical ventilation using tidal volumes around 10 ml/kg and zero positive end-expiratory pressure is still commonly used in anesthesia. This strategy has been shown to aggravate lung injury and inflammation in preinjured lungs but not in healthy lungs. In this study, the authors investigated whether this strategy would result in lung injury during transient endotoxemia in the lungs of healthy animals. Methods Volume-controlled ventilation with a tidal volume of 10 ml/kg and zero positive end-expiratory pressure was applied in two groups of anesthetized-paralyzed rabbits receiving either intravenous injection of 5 mug/kg Escherichia coli lipopolysaccharide (n = 10) or saline (n = 10) 2 h after the start of mechanical ventilation. The third group consisted of 10 spontaneously breathing anesthetized animals receiving lipopolysaccharide. Anesthesia was then continued for 4 h in the three groups while the ventilatory modes were maintained unchanged. Lung injury was studied using blood gases, respiratory physiologic variables, analysis of the bronchoalveolar lavage cell counts, and cytokine concentrations and lung pathologic examination. Results Significant histologic lung alterations, hypoxemia, and altered lung mechanics were observed in rabbits treated with mechanical ventilation and intravenous lipopolysaccharide but not in the mechanically ventilated animals injected with saline or in spontaneously breathing animals treated with lipopolysaccharide. Endotoxemic ventilated animals also had significantly more lung inflammation as assessed by the alveolar concentration of neutrophils, and the concentrations of the chemokines interleukin 8 and growth-related oncogen alpha. Conclusions These results showed that positive-pressure mechanical ventilation using a tidal volume of 10 ml/kg and zero positive end-expiratory pressure was harmful in the setting of endotoxemia, suggesting that the use of this ventilator strategy in the operating room may predispose to lung injury when endotoxemia occurs.

scholarly journals Combined Negative- and Positive-Pressure Ventilation for the Treatment of ARDS

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Konstantinos Raymondos ◽  
Jörg Ahrens ◽  
Ulrich Molitoris
Keyword(s):  
High Mortality ◽  
Negative Pressure ◽  
Pressure Support ◽  
Positive Pressure Ventilation ◽  
Standard Of Care ◽  
Positive Pressure ◽  
Current Standard ◽  
Case Presentation ◽  
Negative Pressure Ventilation

Objective. Tracheal intubation and positive-pressure ventilation as the current standard of care for the adult respiratory distress syndrome (ARDS) seem to have reached their limit in terms of a further relevant reduction of the still very high mortality.Case Presentation. A 75-year-old male patient developed ARDS after abscess drainage with deteriorating oxygenation, despite positive end-expiratory pressure (PEEP) values above 15 cm H2O. We applied external negative-pressure ventilation with a chamber respirator using −33 cm H2O at inspiration and −15 cm H2O at expiration, combined with conventional pressure support using a PEEP of about 8 cm H2O and a pressure support of 4–12 cm H2O. Alveolar infiltrates disappeared rapidly and PaO2/FiO2values surpassed 300 mmHg after the first application and 500 mmHg after the second. Negative-pressure ventilation was used for 6–18 hours/day over five days. Now, 13 years later, the patient is still alive and has a good quality of life.Conclusion. Using this or similar concepts, not only in intubated patients but also as a noninvasive approach in patients with ARDS, offers new options that may genuinely differ from the present therapeutic approaches and may, therefore, have the potential to decrease the present high mortality from ARDS.

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