scholarly journals Pressure-limited sustained inflation vs. gradual tidal inflations for resuscitation in preterm lambs

2015 ◽  
Vol 118 (7) ◽  
pp. 890-897 ◽  
Author(s):  
David G. Tingay ◽  
Graeme R. Polglase ◽  
Risha Bhatia ◽  
Clare A. Berry ◽  
Robert J. Kopotic ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Lung Injury ◽  
Gradual Increase ◽  
Lung Mechanics ◽  
Arterial Oxygen ◽  
Volume Distribution ◽  
Dependent Lung ◽  
Impedance Tomography ◽  
Sustained Inflation ◽  
Mrna Markers

Support of the mechanically complex preterm lung needs to facilitate aeration while avoiding ventilation heterogeneities: whether to achieve this gradually or quickly remains unclear. We compared the effect of gradual vs. constant tidal inflations and a pressure-limited sustained inflation (SI) at birth on gas exchange, lung mechanics, gravity-dependent lung volume distribution, and lung injury in 131-day gestation preterm lambs. Lambs were resuscitated with either 1) a 20-s, 40-cmH2O pressure-limited SI (PressSI), 2) a gradual increase in tidal volume (Vt) over 5-min from 3 ml/kg to 7 ml/kg (IncrVt), or 3) 7 ml/kg Vt from birth. All lambs were subsequently ventilated for 15 min with 7 ml/kg Vt with the same end-expiratory pressure. Lung mechanics, gas exchange and spatial distribution of end-expiratory volume (EEV), and tidal ventilation (electrical impedance tomography) were recorded regularly. At 15 min, early mRNA tissue markers of lung injury were assessed. The IncrVt group resulted in greater tissue hysteresivity at 5 min ( P = 0.017; two-way ANOVA), higher alveolar-arterial oxygen difference from 10 min ( P < 0.01), and least uniform gravity-dependent distribution of EEV. There were no other differences in lung mechanics between groups, and the PressSI and 7 ml/kg Vt groups behaved similarly throughout. EEV was more uniformly distributed, but Vt least so, in the PressSI group. There were no differences in mRNA markers of lung injury. A gradual increase in Vt from birth resulted in less recruitment of the gravity-dependent lung with worse oxygenation. There was no benefit of a SI at birth over mechanical ventilation with 7 ml/kg Vt.

scholarly journals An individualized approach to sustained inflation duration at birth improves outcomes in newborn preterm lambs

2015 ◽  
Vol 309 (10) ◽  
pp. L1138-L1149 ◽  
Author(s):  
David G. Tingay ◽  
Anna Lavizzari ◽  
Cornelis E. E. Zonneveld ◽  
Anushi Rajapaksa ◽  
Emanuela Zannin ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Lung Injury ◽  
Positive Pressure Ventilation ◽  
Lung Mechanics ◽  
Positive Pressure ◽  
Impedance Tomography ◽  
Tidal Ventilation ◽  
Sustained Inflation ◽  
Volume Response ◽  
The Impact

A sustained first inflation (SI) at birth may aid lung liquid clearance and aeration, but the impact of SI duration relative to the volume-response of the lung is poorly understood. We compared three SI strategies: 1) variable duration defined by attaining volume equilibrium using real-time electrical impedance tomography (EIT; SIplat); 2) 30 s beyond equilibrium (SIlong); 3) short 30-s SI (SI30); and 4) positive pressure ventilation without SI (no-SI) on spatiotemporal aeration and ventilation (EIT), gas exchange, lung mechanics, and regional early markers of injury in preterm lambs. Fifty-nine fetal-instrumented lambs were ventilated for 60 min after applying the allocated first inflation strategy. At study completion molecular and histological markers of lung injury were analyzed. The time to SI volume equilibrium, and resultant volume, were highly variable; mean (SD) 55 (34) s, coefficient of variability 59%. SIplat and SIlong resulted in better lung mechanics, gas exchange and lower ventilator settings than both no-SI and SI30. At 60 min, alveolar-arterial difference in oxygen was a mean (95% confidence interval) 130 (13, 249) higher in SI30 vs. SIlong group (two-way ANOVA). These differences were due to better spatiotemporal aeration and tidal ventilation, although all groups showed redistribution of aeration towards the nondependent lung by 60 min. Histological lung injury scores mirrored spatiotemporal change in aeration and were greatest in SI30 group ( P < 0.01, Kruskal-Wallis test). An individualized volume-response approach to SI was effective in optimizing aeration, homogeneous tidal ventilation, and respiratory outcomes, while an inadequate SI duration had no benefit over positive pressure ventilation alone.

scholarly journals Effectiveness of individualized lung recruitment strategies at birth: an experimental study in preterm lambs

2017 ◽  
Vol 312 (1) ◽  
pp. L32-L41 ◽  
Author(s):  
David G. Tingay ◽  
Anushi Rajapaksa ◽  
Emanuela Zannin ◽  
Prue M. Pereira-Fantini ◽  
Raffaele L. Dellaca ◽  
...  
Keyword(s):  
Lung Injury ◽  
Fetal Lung ◽  
Lung Mechanics ◽  
Impedance Tomography ◽  
Antenatal Steroids ◽  
Sustained Inflation ◽  
Volume Response ◽  
Distal Lung ◽  
Study Completion ◽  
Lung Liquid

Respiratory transition at birth involves rapidly clearing fetal lung liquid and preventing efflux back into the lung while aeration is established. We have developed a sustained inflation (SIOPT) individualized to volume response and a dynamic tidal positive end-expiratory pressure (PEEP) (open lung volume, OLV) strategy that both enhance this process. We aimed to compare the effect of each with a group managed with PEEP of 8 cmH2O and no recruitment maneuver (No-RM), on gas exchange, lung mechanics, spatiotemporal aeration, and lung injury in 127 ± 1 day preterm lambs. Forty-eight fetal-instrumented lambs exposed to antenatal steroids were ventilated for 60 min after application of the allocated strategy. Spatiotemporal aeration and lung mechanics were measured with electrical impedance tomography and forced-oscillation, respectively. At study completion, molecular and histological markers of lung injury were analyzed. Mean (SD) aeration at the end of the SIOPT and OLV groups was 32 (22) and 38 (15) ml/kg, compared with 17 (10) ml/kg (180 s) in the No-RM ( P = 0.024, 1-way ANOVA). This translated into better oxygenation at 60 min ( P = 0.047; 2-way ANOVA) resulting from better distal lung tissue aeration in SIOPT and OLV. There was no difference in lung injury. Neither SIOPT nor OLV achieved homogeneous aeration. Histological injury and mRNA biomarker upregulation were more likely in the regions with better initial aeration, suggesting volutrauma. Tidal ventilation or an SI achieves similar aeration if optimized, suggesting that preventing fluid efflux after lung liquid clearance is at least as important as fluid clearance during the initial inflation at birth.

Colloidal gold particles as a new in vivo marker of early acute lung injury

2004 ◽  
Vol 287 (4) ◽  
pp. L867-L878 ◽  
Author(s):  
Kai Heckel ◽  
Rainer Kiefmann ◽  
Martina Dörger ◽  
Mechthild Stoeckelhuber ◽  
Alwin E. Goetz
Keyword(s):  
Electron Microscopy ◽  
Acute Lung Injury ◽  
Gas Exchange ◽  
Lung Injury ◽  
Colloidal Gold ◽  
Microvascular Permeability ◽  
Arterial Oxygen ◽  
Control Group ◽  
Gold Particles

Permeability of the endothelial barrier to large molecules plays a pivotal role in the manifestation of early acute lung injury. We present a novel and sensitive technique that brings microanatomical visualization and quantification of microvascular permeability in line. White New Zealand rabbits were anesthetized and ventilated mechanically. Rabbit serum albumin (RSA) was labeled with colloidal gold particles. We quantified macromolecular leakage of gold-labeled RSA and thickening of the gas exchange distance by electron microscopy, taking into account morphology of microvessels. The control group receiving a saline solution represented a normal gas exchange barrier without extravasation of gold-labeled albumin. Infusion of lipopolysaccharide (LPS) resulted in a significant displacement of gold-labeled albumin into pulmonary cells, the lung interstitium, and even the alveolar space. Correspondingly, intravital fluorescence microscopy and digital image analysis indicated thickening of width of alveolar septa. The findings were accompanied by a deterioration of alveolo-arterial oxygen difference, whereas wet/dry ratio and albumin concentration in the bronchoalveolar lavage fluid failed to detect that early stage of pulmonary edema. Inhibition of the nuclear enzyme poly(ADP-ribose) synthetase by 3-aminobenzamide prevented LPS-induced microvascular injury. To summarize: colloidal gold particles visualized by standard electron microscopy are a new and very sensitive in vivo marker of microvascular permeability in early acute lung injury. This technique enabling detailed microanatomical and quantitative pathophysiological characterization of edema formation can form the basis for evaluating novel treatment strategies against acute lung injury.

What hinders pulmonary gas exchange and changes distribution of ventilation in immobilized white rhinoceroses (Ceratotherium simum) in lateral recumbency?

2020 ◽  
Vol 129 (5) ◽  
pp. 1140-1149
Author(s):  
Martina Mosing ◽  
Andreas D. Waldmann ◽  
Muriel Sacks ◽  
Peter Buss ◽  
Jordyn M. Boesch ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Breath Holding ◽  
Dependent Lung ◽  
Regional Ventilation ◽  
Impedance Tomography ◽  
Ventilation And Perfusion ◽  
Lateral Recumbency ◽  
Nondependent Lung

Electrical impedance tomography measurements of regional ventilation and perfusion applied to etorphine-immobilized white rhinoceroses in lateral recumbency revealed a pronounced disproportional shift of the measured ventilation and perfusion toward the nondependent lung. The dependent lung was minimally ventilated and perfused, but still aerated. Perfusion was found primarily around the hilum of the nondependent lung. These shifts can explain the gas exchange impairments found in this study. Breath holding can redistribute ventilation.

scholarly journals Derecruitment Test and Surfactant Therapy in Patients with Acute Lung Injury

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Alexey A. Smetkin ◽  
Vsevolod V. Kuzkov ◽  
Konstantin M. Gaidukov ◽  
Lars J. Bjertnaes ◽  
Mikhail Y. Kirov
Keyword(s):  
Acute Lung Injury ◽  
Gas Exchange ◽  
Lung Injury ◽  
Predictive Value ◽  
Conventional Therapy ◽  
Therapy Group ◽  
Lung Mechanics ◽  
Lung Water ◽  
Mechanically Ventilated ◽  
Water Index

Introduction. A recruitment maneuver (RM) may improve gas exchange in acute lung injury (ALI). The aim of our study was to assess the predictive value of a derecruitment test in relation to RM and to evaluate the efficacy of RM combined with surfactant instillation in patients with ALI.Materials and Methods. Thirteen adult mechanically ventilated patients with ALI were enrolled into a prospective pilot study. The patients received protective ventilation and underwent RM followed by a derecruitment test. After a repeat RM, bovine surfactant (surfactant group,n=6) or vehicle only (conventional therapy group,n=7) was instilled endobronchially. We registered respiratory and hemodynamic parameters, including extravascular lung water index (EVLWI).Results. The derecruitment test decreased the oxygenation in 62% of the patients. We found no significant correlation between the responses to the RM and to the derecruitment tests. The baseline EVLWI correlated with changes in SpO2following the derecruitment test. The surfactant did not affect gas exchange and lung mechanics but increased EVLWI at 24 and 32 hrs.Conclusions. Our study demonstrated no predictive value of the derecruitment test regarding the effects of RM. Surfactant instillation was not superior to conventional therapy and might even promote pulmonary edema in ALI.

Hemodilution during Venous Gas Embolization Improves Gas Exchange, without Altering V̇A/Q̇ or Pulmonary Blood Flow Distributions 

1999 ◽  
Vol 91 (6) ◽  
pp. 1861-1861 ◽  
Author(s):  
Steven Deem ◽  
Steven McKinney ◽  
Nayak L. Polissar ◽  
Richard G. Hedges ◽  
Erik R. Swenson
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Lung Injury ◽  
Partial Pressure ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Arterial Oxygen ◽  
Control Group ◽  
Blood Flow Distribution ◽  
Over Time

Background Isovolemic anemia results in improved gas exchange in rabbits with normal lungs but in relatively poorer gas exchange in rabbits with whole-lung atelectasis. In the current study, the authors characterized the effects of hemodilution on gas exchange in a distinct model of diffuse lung injury: venous gas embolization. Methods Twelve anesthetized rabbits were mechanically ventilated at a fixed rate and volume. Gas embolization was induced by continuous infusion of nitrogen via an internal jugular venous catheter. Serial hemodilution was performed in six rabbits by simultaneous withdrawal of blood and infusion of an equal volume of 6% hetastarch; six rabbits were followed as controls over time. Measurements included hemodynamic parameters and blood gases, ventilation-perfusion (V(A)/Q) distribution (multiple inert gas elimination technique), pulmonary blood flow distribution (fluorescent microspheres), and expired nitric oxide (NO; chemoluminescence). Results Venous gas embolization resulted in a decrease in partial pressure of arterial oxygen (PaO2) and an increase in partial pressure of arterial carbon dioxide (PaCO2), with markedly abnormal overall V(A)/Q distribution and a predominance of high V(A)/Q areas. Pulmonary blood flow distribution was markedly left-skewed, with low-flow areas predominating. Hematocrit decreased from 30+/-1% to 11+/-1% (mean +/- SE) with hemodilution. The alveolar-arterial PO2 (A-aPO2) difference decreased from 375+/-61 mmHg at 30% hematocrit to 218+/-12.8 mmHg at 15% hematocrit, but increased again (301+/-33 mmHg) at 11% hematocrit. In contrast, the A-aPO2 difference increased over time in the control group (P &lt; 0.05 between groups over time). Changes in PaO2 in both groups could be explained in large part by variations in intrapulmonary shunt and mixed venous oxygen saturation (SvO2); however, the improvement in gas exchange with hemodilution was not fully explained by significant changes in V(A)/Q or pulmonary blood flow distributions, as quantitated by the coefficient of variation (CV), fractal dimension, and spatial correlation of blood flow. Expired NO increased with with gas embolization but did not change significantly with time or hemodilution. Conclusions Isovolemic hemodilution results in improved oxygen exchange in rabbits with lung injury induced by gas embolization. The mechanism for this improvement is not clear.

Sustained improvement of gas exchange and lung mechanics by vaporized perfluorocarbon inhalation in piglet acute lung injury model

2013 ◽  
Vol 8 (2) ◽  
pp. 160-166 ◽  
Author(s):  
Xiaoguang Wang ◽  
Jianpeng Zhang ◽  
Xiaoling Li ◽  
Youning Liu ◽  
Haibo Yang ◽  
...  
Keyword(s):  
Acute Lung Injury ◽  
Gas Exchange ◽  
Lung Injury ◽  
Lung Mechanics ◽  
Sustained Improvement ◽  
Injury Model ◽  
Lung Injury Model

scholarly journals Monitoring Expired CO2 Kinetics to Individualize Lung-Protective Ventilation in Patients With the Acute Respiratory Distress Syndrome

2021 ◽  
Vol 12 ◽  
Author(s):  
Fernando Suárez-Sipmann ◽  
Jesús Villar ◽  
Carlos Ferrando ◽  
Juan A. Sánchez-Giralt ◽  
Gerardo Tusman
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Gas Exchange ◽  
Lung Injury ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Lung Volume ◽  
Cyclic Deformation ◽  
Distress Syndrome ◽  
Pulmonary Ventilation ◽  
Lung Mechanics

Mechanical ventilation (MV) is a lifesaving supportive intervention in the management of acute respiratory distress syndrome (ARDS), buying time while the primary precipitating cause is being corrected. However, MV can contribute to a worsening of the primary lung injury, known as ventilation-induced lung injury (VILI), which could have an important impact on outcome. The ARDS lung is characterized by diffuse and heterogeneous lung damage and is particularly prone to suffer the consequences of an excessive mechanical stress imposed by higher airway pressures and volumes during MV. Of major concern is cyclic overdistension, affecting those lung segments receiving a proportionally higher tidal volume in an overall reduced lung volume. Theoretically, healthier lung regions are submitted to a larger stress and cyclic deformation and thus at high risk for developing VILI. Clinicians have difficulties in detecting VILI, particularly cyclic overdistension at the bedside, since routine monitoring of gas exchange and lung mechanics are relatively insensitive to this mechanism of VILI. Expired CO2 kinetics integrates relevant pathophysiological information of high interest for monitoring. CO2 is produced by cell metabolism in large daily quantities. After diffusing to tissue capillaries, CO2 is transported first by the venous and then by pulmonary circulation to the lung. Thereafter diffusing from capillaries to lung alveoli, it is finally convectively transported by lung ventilation for its elimination to the atmosphere. Modern readily clinically available sensor technology integrates information related to pulmonary ventilation, perfusion, and gas exchange from the single analysis of expired CO2 kinetics measured at the airway opening. Current volumetric capnography (VCap), the representation of the volume of expired CO2 in one single breath, informs about pulmonary perfusion, end-expiratory lung volume, dead space, and pulmonary ventilation inhomogeneities, all intimately related to cyclic overdistension during MV. Additionally, the recently described capnodynamic method provides the possibility to continuously measure the end-expiratory lung volume and effective pulmonary blood flow. All this information is accessed non-invasively and breath-by-breath helping clinicians to personalize ventilatory settings at the bedside and minimize overdistension and cyclic deformation of lung tissue.

Continuous tracheal gas insufflation during partial liquid ventilation in juvenile rabbits with acute lung injury

2004 ◽  
Vol 96 (4) ◽  
pp. 1415-1424 ◽  
Author(s):  
Guangfa Zhu ◽  
Thomas H. Shaffer ◽  
Marla R. Wolfson
Keyword(s):  
Acute Lung Injury ◽  
Gas Exchange ◽  
Lung Injury ◽  
Combined Treatment ◽  
Peak Inspiratory Pressure ◽  
Oxygenation Index ◽  
Lung Mechanics ◽  
Partial Liquid Ventilation ◽  
Liquid Ventilation ◽  
Tracheal Gas Insufflation

To examine the hypothesis that combined treatment with tracheal gas insufflation (TGI) and partial liquid ventilation (PLV) may improve pulmonary outcome relative to either treatment alone in acute lung injury (ALI), saline lavage lung injury was induced in 24 anesthetized, ventilated juvenile rabbits that were then randomly assigned to receive ( n = 6/group) 1) conventional mechanical ventilation (CMV) alone, 2) continuous TGI at 0.5 l/min, 3) PLV with perfluorochemical liquid, and 4) combined TGI and PLV (TGI + PLV), and subsequently ventilated with minimized pressures and tidal volume (Vt) to keep arterial Po2 (PaO2) >100 Torr and arterial Pco2 (PaCO2) at 45-60 Torr for 4 h. Gas exchange, lung mechanics, myeloperoxidase, IL-8, and histomorphometry [including expansion index (EI)] were assessed. The CMV group showed no improvement in lung mechanics and gas exchange; all treated groups had significant increases in compliance, PaO2, ventilation efficacy index (VEI), and EI, and decreases in PaCO2, oxygenation index, physiological dead space-to-Vt ratio (Vd/Vt), myeloperoxidase, and IL-8, relative to the CMV group. TGI resulted in lower peak inspiratory pressure, Vt, Vd/Vt, and greater VEI vs. PLV group; PLV resulted in greater compliance, PaO2, and EI vs. TGI. TGI + PLV resulted in decreased peak inspiratory pressure, Vt, Vd/Vt, and increased VEI compared with TGI, improved compliance and EI compared with PLV, and a further increase in PaO2 and oxygenation index and a decrease in PaCO2 vs. either treatment alone. These results indicate that combined treatment of TGI and PLV results in improved pulmonary outcome than either treatment alone in this animal model of ALI.

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