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Marchesi, S., Ortiz-Nieto, F., Ahlgren, K. M., Roneus, A., Feinstein, R., Lipcsey, M., . . . Hedenstierna, G. (2019). Abdominal organ perfusion and inflammation in experimental sepsis: a magnetic resonance imaging study. American Journal of Physiology - Gastrointestinal and Liver Physiology, 316(1), G187-G196
Open this publication in new window or tab >>Abdominal organ perfusion and inflammation in experimental sepsis: a magnetic resonance imaging study
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2019 (English)In: American Journal of Physiology - Gastrointestinal and Liver Physiology, ISSN 0193-1857, E-ISSN 1522-1547, Vol. 316, no 1, p. G187-G196Article in journal (Refereed) Published
Abstract [en]

Diffusion-weighted magnetic resonance imaging (DW-MRI) uses water as contrast and enables the study of perfusion in many organs simultaneously in situ. We used DW-MRI in a sepsis model, comparing abdominal organs perfusion with global hemodynamic measurements and inflammation. Sixteen anesthetized piglets were randomized into 3 groups: HighMAP (mean arterial pressure, MAP > 65 mmHg), LowMAP (MAP between 50 and 60 mmHg) and Healthy Controls (HC). Sepsis was obtained with endotoxin and the desired MAP maintained with noradrenaline. After 6 hours DW-MRI was performed. Acute inflammation was assessed with IL-6 and TNFα in abdominal organs, ascites, and blood and by histology of intestine (duodenum). Perfusion of abdominal organs was reduced in the LowMAP group compared to the HighMAP group and HC. Liver perfusion was still reduced by 25% in the HighMAP group compared with HC. Intestinal perfusion did not differ significantly between the study groups. Cytokines concentration were generally higher in the LowMAP group but did not correlate with global hemodynamics. However, cytokines correlated with regional perfusion and, for liver and intestine, also with intra-abdominal pressure. Histopathology of intestine worsened with decreasing perfusion. In conclusion, although a low MAP (≤60 mmHg) indicated impeded abdominal perfusion in experimental sepsis, it did not predict inflammation, nor did other global measures of circulation. Decreased abdominal perfusion predicted partially inflammation but intestine, occupying most of the abdomen, and liver, were also affected by intra-abdominal pressure.

Keywords
Abdominal organs, inflammation, magnetic resonance, perfusion, sepsis
National Category
Surgery Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-364356 (URN)10.1152/ajpgi.00151.2018 (DOI)000455670700012 ()30335473 (PubMedID)
Funder
Swedish Heart Lung FoundationSwedish Research Council
Available from: 2018-10-25 Created: 2018-10-25 Last updated: 2019-02-05Bibliographically approved
Strassmann, S., Merten, M., Schäfer, S., de Moll, J., Brodie, D., Larsson, A., . . . Karagiannidis, C. (2019). Impact of sweep gas flow on extracorporeal CO2 removal (ECCO2R). Intensive Care Medicine Experimental, 7, Article ID 17.
Open this publication in new window or tab >>Impact of sweep gas flow on extracorporeal CO2 removal (ECCO2R)
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2019 (English)In: Intensive Care Medicine Experimental, ISSN 1646-2335, E-ISSN 2197-425X, Vol. 7, article id 17Article in journal (Refereed) Published
Abstract [en]

Background: Veno-venous extracorporeal carbon dioxide (CO2) removal (vv-ECCO2R) is increasingly being used in the setting of acute respiratory failure. Blood flow rates range in clinical practice from 200mL/min to more than 1500mL/min, and sweep gas flow rates range from less than 1 to more than 10L/min. The present porcine model study was aimed at determining the impact of varying sweep gas flow rates on CO2 removal under different blood flow conditions and membrane lung surface areas.

Methods: Two different membrane lungs, with surface areas of 0.4 and 0.8m(2), were used in nine pigs with experimentally-induced hypercapnia. During each experiment, the blood flow was increased stepwise from 300 to 900 mL/min, with further increases up to 1800 mL/min with the larger membrane lung in steps of 300 mL/min. Sweep gas was titrated under each condition from 2 to 8L/min in steps of 2 L/min. Extracorporeal CO2 elimination was normalized to a PaCO2 of 45 mmHg before the membrane lung.

Results: Reversal of hypercapnia was only feasible when blood flow rates above 900mL/min were used with a membrane lung surface area of at least 0.8m(2). The membrane lung with a surface of 0.4m(2) allowed a maximum normalized CO2 elimination rate of 416mL/min with 8L/min sweep gas flow and 900mLbloodflow/min. The increase in sweep gas flow from 2 to 8L/min increased normalized CO2 elimination from 35 +/- 5 to 41 +/- 6 with 900mLbloodflow/min, whereas with lower blood flow rates, any increase was less effective, levelling out at 4Lsweepgasflow/min. The membrane lung with a surface area of 0.8 m(2) allowed a maximum normalized CO2 elimination rate of 101 +/- 12 mL/min with increasing influence of sweep gas flow. The delta of normalized CO2 elimination increased from 4 +/- 2 to 26 +/- 7 mL/min with blood flow rates being increased from 300 to 1800 mL/min, respectively.

Conclusions: The influence of sweep gas flow on the CO2 removal capacity of ECCO2R systems depends predominantly on blood flow rate and membrane lung surface area. In this model, considerable CO2 removal occurred only with the larger membrane lung surface of 0.8m(2) and when blood flow rates of >= 900mL/min were used.

Place, publisher, year, edition, pages
SPRINGEROPEN, 2019
Keywords
ARDS, Extracorporeal carbon dioxide removal, COPD, ECCO2R, ECMO
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-381582 (URN)10.1186/s40635-019-0244-3 (DOI)000462730900001 ()30911910 (PubMedID)
Funder
Swedish Heart Lung Foundation
Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2019-04-12Bibliographically approved
Broche, L., Pisa, P., Porra, L., Degrugilliers, L., Bravin, A., Pellegrini, M., . . . Bayat, S. (2019). Individual Airway Closure Characterized In Vivo by Phase-Contrast CT Imaging in Injured Rabbit Lung. Critical Care Medicine, 47(9), E774-E781
Open this publication in new window or tab >>Individual Airway Closure Characterized In Vivo by Phase-Contrast CT Imaging in Injured Rabbit Lung
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2019 (English)In: Critical Care Medicine, ISSN 0090-3493, E-ISSN 1530-0293, Vol. 47, no 9, p. E774-E781Article in journal (Refereed) Published
Abstract [en]

Objectives: Airway closure is involved in adverse effects of mechanical ventilation under both general anesthesia and in acute respiratory distress syndrome patients. However, direct evidence and characterization of individual airway closure is lacking. Here, we studied the same individual peripheral airways in intact lungs of anesthetized and mechanically ventilated rabbits, at baseline and following lung injury, using high-resolution synchrotron phase-contrast CT.

Design: Laboratory animal investigation.

Setting: European synchrotron radiation facility.

Subjects: Six New-Zealand White rabbits.

Interventions: The animals were anesthetized, paralyzed, and mechanically ventilated in pressure-controlled mode (tidal volume, 6 mL/kg; respiratory rate, 40; Fio(2), 0.6; inspiratory:expiratory, 1:2; and positive end-expiratory pressure, 3 cm H2O) at baseline. Imaging was performed with a 47.5 x 47.5 x 47.5 mu m voxel size, at positive end-expiratory pressure 12, 9, 6, 3, and 0 cm H2O. The imaging sequence was repeated after lung injury induced by whole-lung lavage and injurious ventilation in four rabbits. Cross-sections of the same individual airways were measured.

Measurements and Main Results: The airways were measured at baseline (n = 48; radius, 1.7 to 0.21 mm) and after injury (n = 32). Closure was observed at 0 cm H2O in three of 48 airways (6.3%; radius, 0.350.08 mm at positive end-expiratory pressure 12) at baseline and five of 32 (15.6%; radius, 0.28 +/- 0.09 mm) airways after injury. Cross-section was significantly reduced at 3 and 0 cm H2O, after injury, with a significant relation between the relative change in cross-section and airway radius at 12 cm H2O in injured, but not in normal lung (R = 0.60; p < 0.001).

Conclusions: Airway collapsibility increases in the injured lung with a significant dependence on airway caliber. We identify "compliant collapse" as the main mechanism of airway closure in initially patent airways, which can occur at more than one site in individual airways.

Place, publisher, year, edition, pages
LIPPINCOTT WILLIAMS & WILKINS, 2019
Keywords
airway closure, mechanical ventilation, phase-contrast imaging, respiratory distress syndrome, adult, tomography, x-ray computed, ventilator-induced lung injury
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-394204 (URN)10.1097/CCM.0000000000003838 (DOI)000484224200007 ()31162202 (PubMedID)
Available from: 2019-10-04 Created: 2019-10-04 Last updated: 2019-10-04Bibliographically approved
Lind, L., Sundström, J., Larsson, A., Lampa, E., Ärnlov, J. & Ingelsson, E. (2019). Longitudinal effects of aging on plasma proteins levels in older adults - associations with kidney function and hemoglobin levels. PLoS ONE, 14(2), Article ID e0212060.
Open this publication in new window or tab >>Longitudinal effects of aging on plasma proteins levels in older adults - associations with kidney function and hemoglobin levels
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2019 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 14, no 2, article id e0212060Article in journal (Refereed) Published
Abstract [en]

Background A targeted proteomics chip has been shown to be useful to discover novel associations of proteins with cardiovascular disease. We investigated how these proteins change with aging, and whether this change is related to a decline in kidney function, or to a change in hemoglobin levels. Material and methods In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, including 1,016 participants from the general population aged 70 at baseline, 84 proteins were measured at ages 70, 75, 80. At these occasions, glomerular filtration rate (eGFR) was estimated and the hemoglobin levels were measured. Results Sixty-one of the 84 evaluated proteins changed significantly during the 10-year follow-up (multiple testing-adjusted alpha = 0.00059), most showing an increase. The change in eGFR was inversely related to changes of protein levels for the vast majority of proteins (74%). The change in hemoglobin was significantly related to the change in 40% of the evaluated proteins, with no obvious preference of the direction of these relationships. Conclusion The majority of evaluated proteins increased with aging in adults. Therefore, normal ranges for proteins might be given in age-strata. The increase in protein levels was associated with the degree of reduction in eGFR for the majority of proteins, while no clear pattern was seen for the relationships between the proteins and the change in hemoglobin levels. Studies on changes in urinary proteins are warranted to understand the association between the reduction in eGFR and increase in plasma protein levels.

Place, publisher, year, edition, pages
PUBLIC LIBRARY SCIENCE, 2019
National Category
Gerontology, specialising in Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-379592 (URN)10.1371/journal.pone.0212060 (DOI)000459710700009 ()30802263 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, 2013.0126
Available from: 2019-03-18 Created: 2019-03-18 Last updated: 2019-03-18Bibliographically approved
Reinius, H., Batista Borges, J., Engström, J., Ahlgren, O., Lennmyr, F., Larsson, A. & Fredén, F. (2019). Optimal PEEP during one-lung ventilation with capnothorax: An experimental study. Acta Anaesthesiologica Scandinavica, 63(2), 222-231
Open this publication in new window or tab >>Optimal PEEP during one-lung ventilation with capnothorax: An experimental study
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2019 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 63, no 2, p. 222-231Article in journal (Refereed) Published
Abstract [en]

Background: One‐lung ventilation (OLV) with induced capnothorax carries the risk of severely impaired ventilation and circulation. Optimal PEEP may mitigate the physiological perturbations during these conditions.

Methods: Right‐sided OLV with capnothorax (16 cm H2O) on the left side was initiated in eight anesthetized, muscle‐relaxed piglets. A recruitment maneuver and a decremental PEEP titration from PEEP 20 cm H2O to zero end‐expiratory pressure (ZEEP) was performed. Regional ventilation and perfusion were studied with electrical impedance tomography and computer tomography of the chest was used. End‐expiratory lung volume and hemodynamics were recorded and.

Results: PaO2 peaked at PEEP 12 cm H2O (49 ± 14 kPa) and decreased to 11 ± 5 kPa at ZEEP (P < 0.001). PaCO2 was 9.5 ± 1.3 kPa at 20 cm H2O PEEP and did not change when PEEP step‐wise was reduced to 12 cm H2O PaCO2. At lower PEEP, PaCO2 increased markedly. The ventilatory driving pressure was lowest at PEEP 14 cm H2O (19.6 ± 5.8 cm H2O) and increased to 38.3 ± 6.1 cm H2O at ZEEP (P < 0.001). When reducing PEEP below 12‐14 cm H2O ventilation shifted from the dependent to the nondependent regions of the ventilated lung (P = 0.003), and perfusion shifted from the ventilated to the nonventilated lung (P = 0.02).

Conclusion: Optimal PEEP was 12‐18 cm H2O and probably relates to capnothorax insufflation pressure. With suboptimal PEEP, ventilation/perfusion mismatch in the ventilated lung and redistribution of blood flow to the nonventilated lung occurred.

Keywords
anesthesia, capnothorax, cardio-thoracic surgery, one lung ventilation, optimal PEEP, PEEP titration
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-268620 (URN)10.1111/aas.13247 (DOI)000454814700012 ()30132806 (PubMedID)
Funder
Swedish Heart Lung Foundation
Note

Title in thesis list of papers: Optimal PEEP during one lung ventilation with capnothorax. An experimental study

Available from: 2015-12-08 Created: 2015-12-08 Last updated: 2019-01-31Bibliographically approved
Scaramuzzo, G., Broche, L., Pellegrini, M., Porra, L., Derosa, S., Tannoia, A. P., . . . Perchiazzi, G. (2019). Regional Behavior of Airspaces During Positive Pressure Reduction Assessed by Synchrotron Radiation Computed Tomography. Frontiers in Physiology, 10, Article ID 719.
Open this publication in new window or tab >>Regional Behavior of Airspaces During Positive Pressure Reduction Assessed by Synchrotron Radiation Computed Tomography
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2019 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 10, article id 719Article in journal (Refereed) Published
Abstract [en]

Introduction: The mechanisms of lung inflation and deflation are only partially known. Ventilatory strategies to support lung function rely upon the idea that lung alveoli are isotropic balloons that progressively inflate or deflate and that lung pressure/volume curves derive only by the interplay of critical opening pressures, critical closing pressures, lung history, and position of alveoli inside the lung. This notion has been recently challenged by subpleural microscopy, magnetic resonance, and computed tomography (CT). Phase-contrast synchrotron radiation CT (PC-SRCT) can yield in vivo images at resolutions higher than conventional CT.

Objectives: We aimed to assess the numerosity (ASden) and the extension of the surface of airspaces (ASext) in healthy conditions at different volumes, during stepwise lung deflation, in concentric regions of the lung. Methods: The study was conducted in seven anesthetized New Zealand rabbits. They underwent PC-SRCT scans (resolution of 47.7 mu m) of the lung at five decreasing positive end expiratory pressure (PEEP) levels of 12, 9, 6, 3, and 0 cmH(2)O during end-expiratory holds. Three concentric regions of interest (ROIs) of the lung were studied: subpleural, mantellar, and core. The images were enhanced by phase contrast algorithms. ASden and ASext were computed by using the Image Processing Toolbox for MatLab. Statistical tests were used to assess any significant difference determined by PEEP or ROI on ASden and ASext.

Results: When reducing PEEP, in each ROI the ASden significantly decreased. Conversely, ASext variation was not significant except for the core ROI. In the latter, the angular coefficient of the regression line was significantly low.

Conclusion: The main mechanism behind the decrease in lung volume at PEEP reduction is derecruitment. In our study involving lung regions laying on isogravitational planes and thus equally influenced by gravitational forces, airspace numerosity and extension of surface depend on the local mechanical properties of the lung.

Keywords
recruitment, VILI, alveoli, kinetics, SRCT
National Category
Respiratory Medicine and Allergy Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-389594 (URN)10.3389/fphys.2019.00719 (DOI)000471313900001 ()31231245 (PubMedID)
Funder
Swedish Research Council, K2015-99X-22731-01-4Swedish Heart Lung Foundation
Available from: 2019-07-25 Created: 2019-07-25 Last updated: 2019-07-25Bibliographically approved
Lundin, S., Persson, P. & Larsson, A. (2019). Strategies to Adjust Positive End-Expiratory Pressure in Patients With ARDS [Letter to the editor]. Journal of the American Medical Association (JAMA), 322(6), 581-581
Open this publication in new window or tab >>Strategies to Adjust Positive End-Expiratory Pressure in Patients With ARDS
2019 (English)In: Journal of the American Medical Association (JAMA), ISSN 0098-7484, E-ISSN 1538-3598, Vol. 322, no 6, p. 581-581Article in journal, Letter (Other academic) Published
Place, publisher, year, edition, pages
AMER MEDICAL ASSOC, 2019
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-394147 (URN)10.1001/jama.2019.7884 (DOI)000481799500029 ()31408129 (PubMedID)
Available from: 2019-10-04 Created: 2019-10-04 Last updated: 2019-10-04Bibliographically approved
Klarin, B., Larsson, A., Molin, G. & Jeppsson, B. (2019). Susceptibility to antibiotics in isolates of Lactobacillus plantarum RAPD-type Lp299v, harvested from antibiotic treated, critically ill patients after administration of probiotics.. MicrobiologyOpen, 8(2), Article ID e00642.
Open this publication in new window or tab >>Susceptibility to antibiotics in isolates of Lactobacillus plantarum RAPD-type Lp299v, harvested from antibiotic treated, critically ill patients after administration of probiotics.
2019 (English)In: MicrobiologyOpen, ISSN 2045-8827, E-ISSN 2045-8827, Vol. 8, no 2, article id e00642Article in journal (Refereed) Published
Abstract [en]

Recultured Lactobacillus plantarum 299v-like strains were tested regarding antibiotic susceptibility, and no decrease was detected. Antibiotics are frequently used to treat patients in intensive care units (ICUs) and are associated with a significant risk of selection of resistant bacterial strains. In particular, it is possible that genetic transfer of antibiotic resistance to the resident gastrointestinal flora, as well as to administered probiotics, may be increased in the ICU setting. The aim of the present investigation was to detect possible changes in antimicrobial susceptibility in reisolates of the probiotic strain Lactobacillus plantarum 299v (Lp299v) given to antibiotic treated, critically ill patients. Lp299v-like strains were identified in cultures of biopsies and fecal samples from 32 patients given the probiotic strain enterally in two previous ICU studies. The patients received a variety of antibiotics. Isolates with the same genomic RAPD profile (RAPD-type) as Lp299v were obtained to enable monitoring of antibiotic susceptibility by E-tests. Forty-two isolates, collected throughout the course of illness, were tested against 22 different antibiotics. No obvious decrease in susceptibility was found for 21 of the tested antibiotics. There was a tendency toward decreased susceptibility to ampicillin. The stable antibiotic susceptibility profiles of the Lp299v-like isolates studied here suggests this probiotic is less likely to acquire resistance when administered to critically ill patients treated with broad-spectrum antibiotics.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
E-test, Lactobacillus plantarum 299v, antibiotic pressure, antibiotic susceptibility, critically ill patients, probiotics
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-368516 (URN)10.1002/mbo3.642 (DOI)000459746700005 ()29797784 (PubMedID)
Funder
Region Skåne
Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2019-03-21Bibliographically approved
Ahlström, J. Z., Massaro, F., Mikolka, P., Feinstein, R., Perchiazzi, G., Basabe-Burgos, O., . . . Rising, A. (2019). Synthetic surfactant with a recombinant surfactant protein C analogue improves lung function and attenuates inflammation in a model of acute respiratory distress syndrome in adult rabbits. Respiratory Research, 20, Article ID 245.
Open this publication in new window or tab >>Synthetic surfactant with a recombinant surfactant protein C analogue improves lung function and attenuates inflammation in a model of acute respiratory distress syndrome in adult rabbits
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2019 (English)In: Respiratory Research, ISSN 1465-9921, E-ISSN 1465-993X, Vol. 20, article id 245Article in journal (Refereed) Published
Abstract [en]

AimIn acute respiratory distress syndrome (ARDS) damaged alveolar epithelium, leakage of plasma proteins into the alveolar space and inactivation of pulmonary surfactant lead to respiratory dysfunction. Lung function could potentially be restored with exogenous surfactant therapy, but clinical trials have so far been disappointing. These negative results may be explained by inactivation and/or too low doses of the administered surfactant. Surfactant based on a recombinant surfactant protein C analogue (rSP-C33Leu) is easy to produce and in this study we compared its effects on lung function and inflammation with a commercial surfactant preparation in an adult rabbit model of ARDS.MethodsARDS was induced in adult New Zealand rabbits by mild lung-lavages followed by injurious ventilation (V-T 20m/kg body weight) until P/F ratio<26.7kPa. The animals were treated with two intratracheal boluses of 2.5mL/kg of 2% rSP-C33Leu in DPPC/egg PC/POPG, 50:40:10 or poractant alfa (Curosurf (R)), both surfactants containing 80mg phospholipids/mL, or air as control. The animals were subsequently ventilated (V-T 8-9m/kg body weight) for an additional 3h and lung function parameters were recorded. Histological appearance of the lungs, degree of lung oedema and levels of the cytokines TNF alpha IL-6 and IL-8 in lung homogenates were evaluated.ResultsBoth surfactant preparations improved lung function vs. the control group and also reduced inflammation scores, production of pro-inflammatory cytokines, and formation of lung oedema to similar degrees. Poractant alfa improved compliance at 1h, P/F ratio and PaO2 at 1.5h compared to rSP-C33Leu surfactant.ConclusionThis study indicates that treatment of experimental ARDS with synthetic lung surfactant based on rSP-C33Leu improves lung function and attenuates inflammation.

Place, publisher, year, edition, pages
BMC, 2019
Keywords
ARDS model, Surfactant protein analogues, Synthetic pulmonary surfactant, Lung function
National Category
Respiratory Medicine and Allergy
Identifiers
urn:nbn:se:uu:diva-398024 (URN)10.1186/s12931-019-1220-x (DOI)000495741500002 ()31694668 (PubMedID)
Funder
Swedish Heart Lung Foundation, 20170531Swedish Heart Lung Foundation, 20150627Swedish Research Council, K2015-99X-22731-01-4Swedish Research Council, 2014-2408Swedish Research Council Formas, 2015-629Vinnova
Available from: 2019-12-05 Created: 2019-12-05 Last updated: 2019-12-05Bibliographically approved
Crockett, D. C., Cronin, J. N., Bommakanti, N., Chen, R., Hahn, C. E., Hedenstierna, G., . . . Formenti, F. (2019). Tidal changes in PaO2 and their relationship to cyclical lung recruitment/derecruitment in a porcine lung injury model. British Journal of Anaesthesia, 122(2), 277-285
Open this publication in new window or tab >>Tidal changes in PaO2 and their relationship to cyclical lung recruitment/derecruitment in a porcine lung injury model
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2019 (English)In: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 122, no 2, p. 277-285Article in journal (Refereed) Published
Abstract [en]

Background: Tidal recruitment/derecruitment (R/D) of collapsed regions in lung injury has been presumed to cause respiratory oscillations in the partial pressure of arterial oxygen (PaO2). These phenomena have not yet been studied simultaneously. We examined the relationship between R/D and PaO2 oscillations by contemporaneous measurement of lung-density changes and PaO2. Methods: Five anaesthetised pigs were studied after surfactant depletion via a saline-lavage model of R/D. The animals were ventilated with a mean fraction of inspired O-2 (FiO(2)) of 0.7 and a tidal volume of 10 ml kg(-1) Protocolised changes in pressure-and volume-controlled modes, inspiratory: expiratory ratio (I:E), and three types of breath-hold manoeuvres were undertaken. Lung collapse and PaO2 were recorded using dynamic computed tomography (dCT) and a rapid PaO2 sensor. Results: During tidal ventilation, the expiratory lung collapse increased when I: E <1 [mean (standard deviation) lung collapse = .7 (8.7)%; P<0.05], but the amplitude of respiratory PaO2 oscillations [ 2.2 (0.8) kPa] did not change during the respiratory cycle. The expected relationship between respiratory PaO2 oscillation amplitude and R/D was therefore not clear. Lung collapse increased during breath-hold manoeuvres at end-expiration and end-inspiration (14% vs 0.9-2.1%; P<0.0001). The mean change in PaO2 from beginning to end of breath-hold manoeuvres was significantly different with each type of breath-hold manoeuvre (P<0.0001). Conclusions: This study in a porcine model of collapse-prone lungs did not demonstrate the expected association between PaO2 oscillation amplitude and the degree of recruitment/derecruitment. The results suggest that changes in pulmonary ventilation are not the sole determinant of changes in PaO2 during mechanical ventilation in lung injury.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
diagnostic imaging, dynamic computed tomorgraphy, lung injury, pulmonary atelectasis, respiration, ventilation
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-377219 (URN)10.1016/j.bja.2018.09.011 (DOI)000456793300025 ()30686314 (PubMedID)
Funder
Swedish Research Council, K2015-99X-2273101-4
Available from: 2019-02-15 Created: 2019-02-15 Last updated: 2019-02-15Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0702-8343

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