scholarly journals Computed tomographic assessment of lung aeration at different positive end-expiratory pressures in a porcine model of intra-abdominal hypertension and lung injury

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Adrian Regli ◽  
Siavash Ahmadi-Noorbakhsh ◽  
Gabrielle Christine Musk ◽  
David Joseph Reese ◽  
Peter Herrmann ◽  
...  
Keyword(s):  
Lung Injury ◽  
Respiratory Mechanics ◽  
Peep Level ◽  
Large Animal Model ◽  
Arterial Oxygen ◽  
Abdominal Pressure ◽  
Large Animal ◽  
Computed Tomographic ◽  
Abdominal Hypertension ◽  
Alveolar Overdistension

Abstract Background Intra-abdominal hypertension (IAH) is common in critically ill patients and is associated with increased morbidity and mortality. High positive end-expiratory pressures (PEEP) can reverse lung volume and oxygenation decline caused by IAH, but its impact on alveolar overdistension is less clear. We aimed to find a PEEP range that would be high enough to reduce atelectasis, while low enough to minimize alveolar overdistention in the presence of IAH and lung injury. Methods Five anesthetized pigs received standardized anesthesia and mechanical ventilation. Peritoneal insufflation of air was used to generate intra-abdominal pressure of 27 cmH2O. Lung injury was created by intravenous oleic acid. PEEP levels of 5, 12, 17, 22, and 27 cmH2O were applied. We performed computed tomography and measured arterial oxygen levels, respiratory mechanics, and cardiac output 5 min after each new PEEP level. The proportion of overdistended, normally aerated, poorly aerated, and non-aerated atelectatic lung tissue was calculated based on Hounsfield units. Results PEEP decreased the proportion of poorly aerated and atelectatic lung, while increasing normally aerated lung. Overdistension increased with each incremental increase in applied PEEP. “Best PEEP” (respiratory mechanics or oxygenation) was higher than the “optimal CT inflation PEEP range” (difference between lower inflection points of atelectatic and overdistended lung) in healthy and injured lungs. Conclusions Our findings in a large animal model suggest that titrating a PEEP to respiratory mechanics or oxygenation in the presence of IAH is associated with increased alveolar overdistension.

scholarly journals Computed tomographic assessment of lung aeration at different positive end-expiratory pressures in a porcine model of intra-abdominal hypertension and lung injury

2020 ◽  
Author(s):  
Adrian Regli ◽  
Siavash Ahmadi-Noorbakhsh ◽  
Gabrielle Christine Mask ◽  
David Joseph Reese ◽  
Peter Herrmann ◽  
...  
Keyword(s):  
Lung Injury ◽  
Peep Level ◽  
Large Animal Model ◽  
Arterial Oxygen ◽  
Abdominal Pressure ◽  
High Peep ◽  
Large Animal ◽  
Computed Tomographic ◽  
Abdominal Hypertension ◽  
The Impact

Abstract Background Intra-abdominal hypertension (IAH) is common in critically ill patients and is associated with increased morbidity and mortality. High positive end-expiratory pressures (PEEP) can reverse lung volume and oxygenation decline caused by IAH in the setting of injured lungs. The impact of high PEEP levels on alveolar overdistension in IAH and lung injury is unknown. We aimed to define an optimal PEEP range during IAH and lung injury that would be high enough to reduce atelectasis formation while low enough to minimize alveolar overdistention. Methods Five anesthetized pigs received standardized anesthesia and mechanical ventilation. Peritoneal insufflation of air was used to generate intra-abdominal pressure of 27cmH2O (20 mmHg). Lung injury was created by intravenous oleic acid. PEEP levels of 5, 12, 17, 22, and 27cmH2O were applied. We performed computed tomography and measured arterial oxygen levels, respiratory mechanics, and cardiac output 5 min after each new PEEP level. The proportion of overdistended, normally aerated, poorly aerated, and non-aerated atelectatic lung tissue was calculated based on Hounsfield units. Results PEEP decreased poorly aerated and atelectatic lung whilst increasing normally aerated lung. Overdistension increased with each incremental increase in applied PEEP. Conclusions Our findings in a large animal model suggest that an optimal PEEP level which maximally recruits atelectatic lung without causing overdistension or hemodynamic compromise may not exist.

scholarly journals A Non‐Lethal Large Animal Model of Traumatic Lung Injury (TLI)

2015 ◽  
Vol 29 (S1) ◽  
Author(s):  
Emidio Sivieri ◽  
Tariq Rahman ◽  
Thomas Shaffer ◽  
Marla Wolfson
Keyword(s):  
Animal Model ◽  
Lung Injury ◽  
Large Animal Model ◽  
Large Animal

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.

Comparison of Intraoral Bone Regeneration with Iliac and Alveolar BMSCs

2018 ◽  
Vol 97 (11) ◽  
pp. 1229-1235 ◽  
Author(s):  
F. Wang ◽  
Y. Zhou ◽  
J. Zhou ◽  
M. Xu ◽  
W. Zheng ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Large Animal Model ◽  
Osteogenic Potential ◽  
Large Animal ◽  
Computed Tomographic ◽  
Great Utility ◽  
Marrow Mesenchymal Stem Cells ◽  
Efficient Alternative ◽  
Autologous Mesenchymal Stem Cells

This study compared the osteogenic potential of bone marrow mesenchymal stem cells (BMSCs) of iliac and alveolar origins (I-BMSCs and Al-BMSCs, respectively), which were transplanted in combination with β tricalcium phosphate (β-TCP) in peri-implant bone defects to investigate the osseointegration between dental implants and tissue-engineered bone in dogs. Specifically, I-BMSCs and Al-BMSCs were cultured, characterized, and seeded on β-TCP and subjected to immunoblotting analyses and alkaline phosphatase activity assays. Subsequently, these cell-seeded scaffolds were implanted into defects that were freshly generated in the mandibular premolar areas of 4 dogs. The defects were covered with β-TCP + Al-BMSCs ( n = 6), β-TCP + I-BMSCs ( n = 6), or β-TCP ( n = 6) or served as the blank control ( n = 6). After healing for 12 wk, the formation and mineralization of new bones were assessed through micro–computed tomographic, histologic, and histomorphometric analyses, and bone-to-implant contacts were measured in the specimens. It was evident that in this large animal model, I-BMSCs and Al-BMSCs manifested similarly strong osteogenic potential, as significantly more new bone was formed in the Al-BMSC and I-BMSC groups than otherwise ( P < 0.01). Therefore, Al-BMSCs are emerging as an efficient alternative for autologous mesenchymal stem cells in regenerative dental and maxillofacial therapies. I-BMSCs, if not restricted in their bioavailability, can also be of great utility in bone tissue–engineering applications.

Acute effects of thoracic irradiation on lung function and structure in awake sheep

1987 ◽  
Vol 62 (1) ◽  
pp. 208-218 ◽  
Author(s):  
J. E. Loyd ◽  
J. M. Bolds ◽  
J. R. Sheller ◽  
S. S. Duke ◽  
A. W. Gillette ◽  
...  
Keyword(s):  
Lung Injury ◽  
Structural Changes ◽  
Morphological Changes ◽  
Large Animal Model ◽  
Large Animal ◽  
Base Line ◽  
Structural Studies ◽  
Peripheral Lung ◽  
Lung Irradiation ◽  
Lung Lymph

To investigate the acute physiological and structural changes after lung irradiation, the effects of whole-lung irradiation were investigated in fourteen sheep. Ten sheep were prepared with vascular and chronic lung lymph catheters, then a week later were given 1,500 rad whole-lung radiation and monitored for 2 days. Four sheep were given the same dose of radiation and were killed 4 h later for structural studies. Lung lymph flow increased at 3 h after radiation (14.6 +/- 2.1 ml/h) to twice the base-line flow rate (7.5 +/- 1.3), with a high lymph-to-plasma protein concentration. Pulmonary arterial pressure increased twofold from base line (18 +/- 1.6 cmH2O) at 2 h after radiation (33 +/- 3.8). Cardiac output and systemic pressure in the aorta did not change after lung radiation. Arterial O2 tension decreased from 85 +/- 3 to 59 +/- 4 Torr at 1 day after radiation. Lymphocyte counts in both blood and lung lymph decreased to a nadir by 4 h and remained low. Thromboxane B2 concentration in lung lymph increased from base line (0.07 +/- 0.03 ng/ml) to peak at 3 h after radiation (8.2 +/- 3.7 ng/ml). The structural studies showed numerous damaged lymphocytes in the peripheral lung and bronchial associated lymphoid tissue. Quantitative analysis of the number of granulocytes in peripheral lung showed no significant change (base line 6.2 +/- 0.8 granulocytes/100 alveoli, 4 h = 10.3 +/- 2.3). The most striking change involved lung airways. The epithelial lining of the majority of airways from intrapulmonary bronchus to respiratory bronchiolus revealed damage with the appearance of intracellular and intercellular cell fragments and granules. This new large animal model of acute radiation lung injury can be used to monitor physiological, biochemical, and morphological changes after lung radiation. It is relevant to the investigation of diffuse oxidant lung injury as well as to radiobiology per se.

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