Mechanical Ventilation Strategies Targeting Different Magnitudes of Collapse and Tidal Recruitment in Porcine Acid Aspiration-Induced Lung Injury

Reducing ventilator-associated lung injury by individualized mechanical ventilation (MV) in patients with Acute Respiratory Distress Syndrome (ARDS) remains a matter of research. We randomly assigned 27 pigs with acid aspiration-induced ARDS to three different MV protocols for 24 h, targeting different magnitudes of collapse and tidal recruitment (collapse&TR): the ARDS-network (ARDSnet) group with low positive end-expiratory pressure (PEEP) protocol (permissive collapse&TR); the Open Lung Concept (OLC) group, PaO2/FiO2 >400 mmHg, indicating collapse&TR <10%; and the minimized collapse&TR monitored by Electrical Impedance Tomography (EIT) group, standard deviation of regional ventilation delay, SDRVD. We analyzed cardiorespiratory parameters, computed tomography (CT), EIT, and post-mortem histology. Mean PEEP over post-randomization measurements was significantly lower in the ARDSnet group at 6.8 ± 1.0 cmH2O compared to the EIT (21.1 ± 2.6 cmH2O) and OLC (18.7 ± 3.2 cmH2O) groups (general linear model (GLM) p < 0.001). Collapse&TR and SDRVD, averaged over all post-randomization measurements, were significantly lower in the EIT and OLC groups than in the ARDSnet group (collapse p < 0.001, TR p = 0.006, SDRVD p < 0.004). Global histological diffuse alveolar damage (DAD) scores in the ARDSnet group (10.1 ± 4.3) exceeded those in the EIT (8.4 ± 3.7) and OLC groups (6.3 ± 3.3) (p = 0.16). Sub-scores for edema and inflammation differed significantly (ANOVA p < 0.05). In a clinically realistic model of early ARDS with recruitable and nonrecruitable collapse, mechanical ventilation involving recruitment and high-PEEP reduced collapse&TR and resulted in improved hemodynamic and physiological conditions with a tendency to reduced histologic lung damage.

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Increased effort during partial ventilatory support is not associated with lung damage in experimental acute lung injury

Intensive Care Medicine Experimental ◽

10.1186/s40635-019-0272-z ◽

2019 ◽

Vol 7 (1) ◽

Cited By ~ 1

Author(s):

Dietrich Henzler ◽

Alf Schmidt ◽

Zhaolin Xu ◽

Nada Ismaiel ◽

Haibo Zhang ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Pressure Support ◽

Diffuse Alveolar Damage ◽

Ventilatory Support ◽

Lung Damage ◽

Respiratory Effort ◽

Sprague Dawley ◽

Mechanical Pressure ◽

Acid Aspiration

Abstract Background An on-going debate exists as to whether partial ventilatory support is lung protective in an acute phase of ARDS. So far, the effects of different respiratory efforts on the development of ventilator-associated lung injury (VALI) have been poorly understood. To test the hypothesis whether respiratory effort itself promotes VALI, acute lung injury (ALI) was induced in 48 Sprague Dawley rats by hydrochloric acid aspiration model. Hemodynamics, gas-exchange, and respiratory mechanics were measured after 4 h of ventilation in pressure control (PC), assist-control (AC), or pressure support with 100% (PS100), 60% (PS60), or 20% (PS20) of the driving pressure during PC. VALI was assessed by histological analysis and biological markers. Results ALI was characterized by a decrease in PaO2/FiO2 from 447 ± 75 to 235 ± 90 mmHg (p < 0.001) and dynamic respiratory compliance from 0.53 ± 0.2 to 0.28 ± 0.1 ml/cmH2O (p < 0.001). There were no differences in hemodynamics or respiratory function among groups at baseline or after 4 h of ventilation. The reduction of mechanical pressure support was associated with a compensatory increase in an inspiratory effort such that peak inspiratory transpulmonary pressures were equal in all groups. The diffuse alveolar damage score showed significant lung injury but was similar among groups. Pro- and anti-inflammatory proteins in the bronchial fluid were comparable among groups. Conclusions In experimental ALI in rodents, the respiratory effort was increased by reducing the pressure support during partial ventilatory support. In the presence of a constant peak inspiratory transpulmonary pressure, an increased respiratory effort was not associated with worsening ventilator-associated lung injury measured by histologic score and biologic markers.

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Individualized Positive End-expiratory Pressure and Regional Gas Exchange in Porcine Lung Injury

Anesthesiology ◽

10.1097/aln.0000000000003151 ◽

2020 ◽

Vol 132 (4) ◽

pp. 808-824

Author(s):

Thomas Muders ◽

Henning Luepschen ◽

Torsten Meier ◽

Andreas Wolfgang Reske ◽

Jörg Zinserling ◽

...

Keyword(s):

Lung Injury ◽

Dead Space ◽

Electrical Impedance ◽

Recruitment Maneuver ◽

Intraabdominal Pressure ◽

High Peep ◽

Lung Collapse ◽

Regional Ventilation ◽

Impedance Tomography ◽

Tidal Recruitment

Abstract Background In acute respiratory failure elevated intraabdominal pressure aggravates lung collapse, tidal recruitment, and ventilation inhomogeneity. Low positive end-expiratory pressure (PEEP) may promote lung collapse and intrapulmonary shunting, whereas high PEEP may increase dead space by inspiratory overdistension. The authors hypothesized that an electrical impedance tomography–guided PEEP approach minimizing tidal recruitment improves regional ventilation and perfusion matching when compared to a table-based low PEEP/no recruitment and an oxygenation-guided high PEEP/full recruitment strategy in a hybrid model of lung injury and elevated intraabdominal pressure. Methods In 15 pigs with oleic acid–induced lung injury intraabdominal pressure was increased by intraabdominal saline infusion. PEEP was set in randomized order: (1) guided by a PEEP/inspired oxygen fraction table, without recruitment maneuver; (2) minimizing tidal recruitment guided by electrical impedance tomography after a recruitment maneuver; and (3) maximizing oxygenation after a recruitment maneuver. Single photon emission computed tomography was used to analyze regional ventilation, perfusion, and aeration. Primary outcome measures were differences in PEEP levels and regional ventilation/perfusion matching. Results Resulting PEEP levels were different (mean ± SD) with (1) table PEEP: 11 ± 3 cm H2O; (2) minimal tidal recruitment PEEP: 22 ± 3 cm H2O; and (3) maximal oxygenation PEEP: 25 ± 4 cm H2O; P < 0.001. Table PEEP without recruitment maneuver caused highest lung collapse (28 ± 11% vs. 5 ± 5% vs. 4 ± 4%; P < 0.001), shunt perfusion (3.2 ± 0.8 l/min vs. 1.0 ± 0.8 l/min vs. 0.7 ± 0.6 l/min; P < 0.001) and dead space ventilation (2.9 ± 1.0 l/min vs. 1.5 ± 0.7 l/min vs. 1.7 ± 0.8 l/min; P < 0.001). Although resulting in different PEEP levels, minimal tidal recruitment and maximal oxygenation PEEP, both following a recruitment maneuver, had similar effects on regional ventilation/perfusion matching. Conclusions When compared to table PEEP without a recruitment maneuver, both minimal tidal recruitment PEEP and maximal oxygenation PEEP following a recruitment maneuver decreased shunting and dead space ventilation, and the effects of minimal tidal recruitment PEEP and maximal oxygenation PEEP were comparable. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

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A Modified Method to Assess Tidal Recruitment by Electrical Impedance Tomography

Journal of Clinical Medicine ◽

10.3390/jcm8081161 ◽

2019 ◽

Vol 8 (8) ◽

pp. 1161 ◽

Cited By ~ 3

Author(s):

Thomas Muders ◽

Benjamin Hentze ◽

Philipp Simon ◽

Felix Girrbach ◽

Michael R.G. Doebler ◽

...

Keyword(s):

Lung Injury ◽

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Characteristic Curve ◽

Receiver Operator Characteristic Curve ◽

Positive End Expiratory Pressure ◽

Regional Ventilation ◽

Impedance Tomography ◽

Modified Method ◽

Tidal Recruitment

Avoiding tidal recruitment and collapse during mechanical ventilation should reduce the risk of lung injury. Electrical impedance tomography (EIT) enables detection of tidal recruitment by measuring regional ventilation delay inhomogeneity (RVDI) during a slow inflation breath with a tidal volume (VT) of 12 mL/kg body weight (BW). Clinical applicability might be limited by such high VTs resulting in high end-inspiratory pressures (PEI) during positive end-expiratory pressure (PEEP) titration. We hypothesized that RVDI can be obtained with acceptable accuracy from reduced slow inflation VTs. In seven ventilated pigs with experimental lung injury, tidal recruitment was quantified by computed tomography at PEEP levels changed stepwise between 0 and 25 cmH2O. RVDI was measured by EIT during slow inflation VTs of 12, 9, 7.5, and 6 mL/kg BW. Linear correlation of tidal recruitment and RVDI was excellent for VTs of 12 (R2 = 0.83, p < 0.001) and 9 mL/kg BW (R2 = 0.83, p < 0.001) but decreased for VTs of 7.5 (R2 = 0.76, p < 0.001) and 6 mL/kg BW (R2 = 0.71, p < 0.001). With any reduction in slow inflation VT, PEI decreased at all PEEP levels. Receiver-Operator-Characteristic curve analyses revealed that RVDI-thresholds to predict distinct amounts of tidal recruitment differ when obtained from different slow inflation VTs. In conclusion, tidal recruitment can sufficiently be monitored by EIT-based RVDI-calculation with a slow inflation of 9 mL/kg BW.

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IL-4/IL-13 Remodeling Pathway of Covid-19 Lung Injury

10.21203/rs.3.rs-34688/v2 ◽

2020 ◽

Author(s):

Caroline Busatta Vaz de Paula ◽

Marina Luise Viola Azevedo ◽

Seigo Nagashima ◽

Ana Paula Camargo Martins ◽

Mineia Alessandra Scaranello Malaquias ◽

...

Keyword(s):

Lung Injury ◽

Transforming Growth Factor Beta ◽

Influenza A ◽

Transforming Growth Factor ◽

Diffuse Alveolar Damage ◽

Tissue Expression ◽

Lung Damage ◽

Control Group ◽

M2 Macrophages ◽

Th17 Response

Abstract Background: The COVID-19 fatality rate is high when compared to the H1N1pdm09 (pandemic Influenza A virus H1N1 subtype) rate, and although both cause an aggravated inflammatory response, the differences in the mechanisms of both pandemic pneumonias need clarification.Objective: To analyze tissue expression of interleukins 4, 13, (IL-4, IL-13), transforming growth factor-beta (TGF-β), and the number of M2 macrophages (Sphingosine-1) in patients who died by COVID-19, comparing with cases of severe pneumopathy caused by H1N1pdm09, and a control group without lung injury.Methods: Six lung biopsy samples of patients who died of SARS-CoV-2 (COVID-19 group) were used and compared with ten lung samples of adults who died from a severe infection of H1N1pdm09 (H1N1 group) and eleven samples of patients who died from different causes without lung injury (CONTROL group). The expression of IL-4, IL-13, TGF-β, and M2 macrophages score (Sphingosine-1) were identified through immunohistochemistry (IHC).Results and conclusion: Significantly higher IL-4 tissue expression and Sphingosine-1 in M2 macrophages was observed in the COVID-19 group when compared to both the H1N1 and the CONTROL groups. Different mechanism of diffuse alveolar damage (DAD) in SARS-CoV-2 compared to H1N1pdm09 infections were observed. IL-4 expression and lung remodeling are phenomena observed in both SARS-COV-2 and H1N1pdm09. However, SARS-CoV-2 seems to promote lung damage through different mechanisms, such as the scarce participation Th1/Th17 response and the higher participation of the Th2. The understanding and management of the aggravated and ineffective immune response elicited by SARS-CoV-2 merits further clarification to improve treatments propose.

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Experimental Ventilator-induced Lung Injury

Anesthesiology ◽

10.1097/aln.0b013e31819fcba9 ◽

2009 ◽

Vol 110 (6) ◽

pp. 1341-1347 ◽

Cited By ~ 27

Author(s):

Jesús Villar ◽

Maria Teresa Herrera-Abreu ◽

Francisco Valladares ◽

Mercedes Muros ◽

Lina Pérez-Méndez ◽

...

Keyword(s):

Lung Injury ◽

Fatal Outcome ◽

Experimental Studies ◽

Lung Damage ◽

Cytokine Gene Expression ◽

High Peep ◽

Necrosis Factor Alpha ◽

Ventilator Induced Lung Injury ◽

Airway Pressures

Background Previous experimental studies of ventilator-induced lung injury have shown that positive end-expiratory pressure (PEEP) is protective. The authors hypothesized that the application of PEEP during volume-controlled ventilation with a moderately high tidal volume (VT) in previously healthy in vivo rats does not attenuate ventilator-induced lung injury if the peak airway pressure markedly increases during the application of PEEP. Methods Sixty healthy, male Sprague-Dawley rats were anesthetized and randomized to be mechanically ventilated for 4 h at (1) VT of 6 ml/kg, (2) VT of 20 ml/kg, or (3) VT of 20 ml/kg plus 10 cm H2O of PEEP. Peak airway pressures, gas exchange, histologic evaluation, mortality, total lung tissue cytokine gene expression, and serum cytokine concentrations were analyzed. Results Peak airway pressures exceeded 30 cm H2O with high VT plus PEEP. All lungs ventilated with high VT had perivascular edema and inflammatory infiltrates. In addition, those ventilated with PEEP had small hemorrhages foci. Five animals from the high VT plus PEEP group died (P = 0.020). Animals ventilated with high VT (with or without PEEP) had a substantial increase in serum interleukin-6 (P = 0.0002), and those ventilated with high VT plus PEEP had a 5.5-fold increase in systemic levels of tumor necrosis factor-alpha (P = 0.007). Conclusions In contrast to previous reports, PEEP exacerbated lung damage and contributed to fatal outcome in an in vivo, mild overdistension model of ventilator-induced lung injury in previously healthy rats. That is, the addition of high PEEP to a constant large VT causes injury in previously healthy animals.

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Protective - ventilation strategy in the acute respiratory distress syndrome

Acta chirurgica iugoslavica ◽

10.2298/aci0403045b ◽

2004 ◽

Vol 51 (3) ◽

pp. 45-49 ◽

Cited By ~ 1

Author(s):

Vladimir Bumbasirevic ◽

V. Bukumirovic ◽

Nada Popovic ◽

V. Nikolic ◽

Nevena Kalezic ◽

...

Keyword(s):

Mechanical Ventilation ◽

Acute Respiratory Distress Syndrome ◽

Lung Injury ◽

Respiratory Distress Syndrome ◽

Respiratory Distress ◽

Distress Syndrome ◽

Pulmonary Ventilation ◽

Lung Damage ◽

Ventilatory Strategy ◽

Protective Ventilation Strategy

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) contribute to progressive hypoxemia in critically ill patients. It has been proved that conventional mechanical ventilation with physiological respiratory volume contributes to further lung damage. In this respect, application of protective ventilatory strategy - pulmonary ventilation with limited volume and pressure can avoid mentioned consequences. The aim of this paper is to discuss mechanims by which elements contained in protective mechanical ventilation of patients with ALI/ARDS prevent further progrssive lung injury, to argue the effects of positive end - expiratory pressure and present insturctions for its application.

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Closed-loop mechanical ventilation for lung injury: a novel physiological-feedback mode following the principles of the open lung concept

Journal of Clinical Monitoring and Computing ◽

10.1007/s10877-017-0040-0 ◽

2017 ◽

Vol 32 (3) ◽

pp. 493-502 ◽

Cited By ~ 4

Author(s):

David Schwaiberger ◽

Philipp A. Pickerodt ◽

Anake Pomprapa ◽

Onno Tjarks ◽

Felix Kork ◽

...

Keyword(s):

Mechanical Ventilation ◽

Lung Injury ◽

Closed Loop ◽

Feedback Mode ◽

Open Lung ◽

Open Lung Concept ◽

Physiological Feedback

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Lung Biopsy Findings in Severe Pulmonary Illness Associated With E-Cigarette Use (Vaping)

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqz182 ◽

2019 ◽

Cited By ~ 18

Author(s):

Sanjay Mukhopadhyay ◽

Mitra Mehrad ◽

Pedro Dammert ◽

Andrea V Arrossi ◽

Rakesh Sarda ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Lung Biopsy ◽

Diffuse Alveolar Damage ◽

Lung Damage ◽

Cigarette Use ◽

Lipoid Pneumonia ◽

Lung Biopsies ◽

Severe Lung

Abstract Objectives The aim of this report is to describe the lung biopsy findings in vaping-associated pulmonary illness. Methods Lung biopsies from eight patients with vaping-associated pulmonary illness were reviewed. Results The biopsies were from eight men (aged 19-61 years) with respiratory symptoms following e-cigarette use (vaping). Workup for infection was negative in all cases, and there was no evidence for other etiologies. Imaging showed diffuse bilateral ground-glass opacities in all patients. Most recovered with corticosteroid therapy, while one died. Lung biopsies (seven transbronchial, one surgical) showed acute lung injury, including organizing pneumonia and/or diffuse alveolar damage. Common features were fibroblast plugs, hyaline membranes, fibrinous exudates, type 2 pneumocyte hyperplasia, and interstitial organization. Some cases featured a sparse interstitial chronic inflammatory infiltrate. Although macrophages were present within the airspaces in all cases, this feature was not prominent, and findings typical of exogenous lipoid pneumonia were absent. Conclusions The histopathology of acute pulmonary illness related to e-cigarette use (vaping) is characterized by acute lung injury patterns, supporting the contention that vaping can cause severe lung damage.

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