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Scharffenberg M, Mandelli M, Bluth T, Simonassi F, Wittenstein J, Teichmann R, Birr K, Kiss T, Ball L, Pelosi P, Schultz MJ, Gama de Abreu M, Huhle R. Respiratory mechanics and mechanical power during low vs. high positive end-expiratory pressure in obese surgical patients - A sub-study of the PROBESE randomized controlled trial. J Clin Anesth 2024; 92:111242. [PMID: 37833194 DOI: 10.1016/j.jclinane.2023.111242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/21/2023] [Accepted: 08/26/2023] [Indexed: 10/15/2023]
Abstract
STUDY OBJECTIVE We aimed to characterize intra-operative mechanical ventilation with low or high positive end-expiratory pressure (PEEP) and recruitment manoeuvres (RM) regarding intra-tidal recruitment/derecruitment and overdistension using non-linear respiratory mechanics, and mechanical power in obese surgical patients enrolled in the PROBESE trial. DESIGN Prospective, two-centre substudy of the international, multicentre, two-arm, randomized-controlled PROBESE trial. SETTING Operating rooms of two European University Hospitals. PATIENTS Forty-eight adult obese patients undergoing abdominal surgery. INTERVENTIONS Intra-operative protective ventilation with either PEEP of 12 cmH2O and repeated RM (HighPEEP+RM) or 4 cmH2O without RM (LowPEEP). MEASUREMENTS The index of intra-tidal recruitment/de-recruitment and overdistension (%E2) as well as airway pressure, tidal volume (VT), respiratory rate (RR), resistance, elastance, and mechanical power (MP) were calculated from respiratory signals recorded after anesthesia induction, 1 h thereafter, and end of surgery (EOS). MAIN RESULTS Twenty-four patients were analyzed in each group. PEEP was higher (mean ± SD, 11.7 ± 0.4 vs. 3.7 ± 0.6 cmH2O, P < 0.001) and driving pressure lower (12.8 ± 3.5 vs. 21.7 ± 6.8 cmH2O, P < 0.001) during HighPEEP+RM than LowPEEP, while VT and RR did not differ significantly (7.3 ± 0.6 vs. 7.4 ± 0.8 ml∙kg-1, P = 0.835; and 14.6 ± 2.5 vs. 15.7 ± 2.0 min-1, P = 0.150, respectively). %E2 was higher in HighPEEP+RM than in LowPEEP following induction (-3.1 ± 7.2 vs. -12.4 ± 10.2%; P < 0.001) and subsequent timepoints. Total resistance and elastance (13.3 ± 3.8 vs. 17.7 ± 6.8 cmH2O∙l∙s-2, P = 0.009; and 15.7 ± 5.5 vs. 28.5 ± 8.4 cmH2O∙l, P < 0.001, respectively) were lower during HighPEEP+RM than LowPEEP. Additionally, MP was lower in HighPEEP+RM than LowPEEP group (5.0 ± 2.2 vs. 10.4 ± 4.7 J∙min-1, P < 0.001). CONCLUSIONS In this sub-cohort of PROBESE, intra-operative ventilation with high PEEP and RM reduced intra-tidal recruitment/de-recruitment as well as driving pressure, elastance, resistance, and mechanical power, as compared with low PEEP. TRIAL REGISTRATION The PROBESE study was registered at www. CLINICALTRIALS gov, identifier: NCT02148692 (submission for registration on May 23, 2014).
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Affiliation(s)
- Martin Scharffenberg
- Department of Anaesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
| | - Maura Mandelli
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Largo Rosanna Benzi 8, 16131 Genoa, Italy
| | - Thomas Bluth
- Department of Anaesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
| | - Francesca Simonassi
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Largo Rosanna Benzi 8, 16131 Genoa, Italy
| | - Jakob Wittenstein
- Department of Anaesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
| | - Robert Teichmann
- Department of Anaesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
| | - Katharina Birr
- Department of Anaesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
| | - Thomas Kiss
- Department of Anaesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; Department of Anaesthesiology, Intensive-, Pain- and Palliative Care Medicine, Radebeul Hospital, Academic Hospital of the Technische Universität Dresden, Heinrich-Zille-Strasse 13, 01445 Radebeul, Germany
| | - Lorenzo Ball
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Largo Rosanna Benzi 8, 16131 Genoa, Italy; Anesthesia and Critical Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Largo Rosanna Benzi, 10, 16132 Genoa, Italy
| | - Paolo Pelosi
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Largo Rosanna Benzi 8, 16131 Genoa, Italy; Anesthesia and Critical Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Largo Rosanna Benzi, 10, 16132 Genoa, Italy
| | - Marcus J Schultz
- Department of Intensive Care, Laboratory of Experimental Intensive Care & Anesthesiology (L E I C A), Amsterdam University Medical Centers, location AMC, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands
| | - Marcelo Gama de Abreu
- Department of Anaesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; Department of Intensive Care and Resuscitation, Anesthesiology Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, 44195, OH, USA; Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, 44195, OH, USA.
| | - Robert Huhle
- Department of Anaesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
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Vivona L, Huhle R, Braune A, Scharffenberg M, Wittenstein J, Kiss T, Kircher M, Herzog P, Herzog M, Millone M, Gama de Abreu M, Bluth T. Variable ventilation versus stepwise lung recruitment manoeuvres for lung recruitment: A comparative study in an experimental model of atelectasis. Eur J Anaesthesiol 2023; 40:501-510. [PMID: 36809307 DOI: 10.1097/eja.0000000000001808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
BACKGROUND Variable ventilation recruits alveoli in atelectatic lungs, but it is unknown how it compares with conventional recruitment manoeuvres. OBJECTIVES To test whether mechanical ventilation with variable tidal volumes and conventional recruitment manoeuvres have comparable effects on lung function. DESIGN Randomised crossover study. SETTING University hospital research facility. ANIMALS Eleven juvenile mechanically ventilated pigs with atelectasis created by saline lung lavage. INTERVENTIONS Lung recruitment was performed using two strategies, both with an individualised optimal positive-end expiratory pressure (PEEP) associated with the best respiratory system elastance during a decremental PEEP trial: conventional recruitment manoeuvres (stepwise increase of PEEP) in pressure-controlled mode) followed by 50 min of volume-controlled ventilation (VCV) with constant tidal volume, and variable ventilation, consisting of 50 min of VCV with random variation in tidal volume. MAIN OUTCOME MEASURES Before and 50 min after each recruitment manoeuvre strategy, lung aeration was assessed by computed tomography, and relative lung perfusion and ventilation (0% = dorsal, 100% = ventral) were determined by electrical impedance tomography. RESULTS After 50 min, variable ventilation and stepwise recruitment manoeuvres decreased the relative mass of poorly and nonaerated lung tissue (percent lung mass: 35.3 ± 6.2 versus 34.2 ± 6.6, P = 0.303); reduced poorly aerated lung mass compared with baseline (-3.5 ± 4.0%, P = 0.016, and -5.2 ± 2.8%, P < 0.001, respectively), and reduced nonaerated lung mass compared with baseline (-7.2 ± 2.5%, P < 0.001; and -4.7 ± 2.8%, P < 0.001 respectively), while the distribution of relative perfusion was barely affected (variable ventilation: -0.8 ± 1.1%, P = 0.044; stepwise recruitment manoeuvres: -0.4 ± 0.9%, P = 0.167). Compared with baseline, variable ventilation and stepwise recruitment manoeuvres increased Pa O 2 (172 ± 85mmHg, P = 0.001; and 213 ± 73 mmHg, P < 0.001, respectively), reduced Pa CO 2 (-9.6 ± 8.1 mmHg, P = 0.003; and -6.7 ± 4.6 mmHg, P < 0.001, respectively), and decreased elastance (-11.4 ± 6.3 cmH 2 O, P < 0.001; and -14.1 ± 3.3 cmH 2 O, P < 0.001, respectively). Mean arterial pressure decreased during stepwise recruitment manoeuvres (-24 ± 8 mmHg, P = 0.006), but not variable ventilation. CONCLUSION In this model of lung atelectasis, variable ventilation and stepwise recruitment manoeuvres effectively recruited lungs, but only variable ventilation did not adversely affect haemodynamics. TRIAL REGISTRATION This study was registered and approved by Landesdirektion Dresden, Germany (DD24-5131/354/64).
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Affiliation(s)
- Luigi Vivona
- From the Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany (LV, RH, AB, MS, JW, TK, PH, MH, MM, MGA, TB), Department of Pathophysiology and Transplantation, University of Milan, Italy (LV), Institute of Nuclear Medicine, University Hospital Carl Gustav Carus, Dresden (AB), Department of Anesthesiology, Elblandklinikum Radebeul, Radebeul (TK), Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe (MK), Drägerwerk AG & Co KGaA, Lübeck, Germany (MK), IRCCS San Martino IST, Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy (MM), Department of Intensive Care and Resuscitation (MGA) and Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio, USA (MGA)
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Herrmann J, Kollisch-Singule M, Satalin J, Nieman GF, Kaczka DW. Assessment of Heterogeneity in Lung Structure and Function During Mechanical Ventilation: A Review of Methodologies. JOURNAL OF ENGINEERING AND SCIENCE IN MEDICAL DIAGNOSTICS AND THERAPY 2022; 5:040801. [PMID: 35832339 PMCID: PMC9132008 DOI: 10.1115/1.4054386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/13/2022] [Indexed: 06/15/2023]
Abstract
The mammalian lung is characterized by heterogeneity in both its structure and function, by incorporating an asymmetric branching airway tree optimized for maintenance of efficient ventilation, perfusion, and gas exchange. Despite potential benefits of naturally occurring heterogeneity in the lungs, there may also be detrimental effects arising from pathologic processes, which may result in deficiencies in gas transport and exchange. Regardless of etiology, pathologic heterogeneity results in the maldistribution of regional ventilation and perfusion, impairments in gas exchange, and increased work of breathing. In extreme situations, heterogeneity may result in respiratory failure, necessitating support with a mechanical ventilator. This review will present a summary of measurement techniques for assessing and quantifying heterogeneity in respiratory system structure and function during mechanical ventilation. These methods have been grouped according to four broad categories: (1) inverse modeling of heterogeneous mechanical function; (2) capnography and washout techniques to measure heterogeneity of gas transport; (3) measurements of heterogeneous deformation on the surface of the lung; and finally (4) imaging techniques used to observe spatially-distributed ventilation or regional deformation. Each technique varies with regard to spatial and temporal resolution, degrees of invasiveness, risks posed to patients, as well as suitability for clinical implementation. Nonetheless, each technique provides a unique perspective on the manifestations and consequences of mechanical heterogeneity in the diseased lung.
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Affiliation(s)
- Jacob Herrmann
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242
| | | | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY 13210
| | - Gary F. Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY 13210
| | - David W. Kaczka
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242; Department of Anesthesia, University of Iowa, Iowa City, IA 52242; Department of Radiology, University of Iowa, Iowa City, IA 52242
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Non-invasive over-distension measurements: data driven vs model-based. J Clin Monit Comput 2022; 37:389-398. [PMID: 35920951 DOI: 10.1007/s10877-022-00900-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 07/22/2022] [Indexed: 10/16/2022]
Abstract
Clinical measurements offer bedside monitoring aiming to minimise unintended over-distension, but have limitations and cannot be predicted for changes in mechanical ventilation (MV) settings and are only available in certain MV modes. This study introduces a non-invasive, real-time over-distension measurement, which is robust, predictable, and more intuitive than current methods. The proposed over-distension measurement, denoted as OD, is compared with the clinically proven stress index (SI). Correlation is analysed via R2 and Spearman rs. The OD safe range corresponding to the unit-less SI safe range (0.95-1.05) is calibrated by sensitivity and specificity test. Validation is fulfilled with 19 acute respiratory distress syndrome (ARDS) patients data (196 cases), including assessment across ARDS severity. Overall correlation between OD and SI yielded R2 = 0.76 and Spearman rs = 0.89. Correlation is higher considering only moderate and severe ARDS patients. Calibration of OD to SI yields a safe range defined: 0 ≤ OD ≤ 0.8 cmH2O. The proposed OD offers an efficient, general, real-time measurement of patient-specific lung mechanics, which is more intuitive and robust than SI. OD eliminates the limitations of SI in MV mode and its less intuitive lung status value. Finally, OD can be accurately predicted for new ventilator settings via its foundation in a validated predictive personalized lung mechanics model. Therefore, OD offers potential clinical value over current clinical methods.
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Scharffenberg M, Wittenstein J, Ran X, Zhang Y, Braune A, Theilen R, Maiello L, Benzi G, Bluth T, Kiss T, Pelosi P, Rocco PRM, Schultz MJ, Kotzerke J, Gama de Abreu M, Huhle R. Mechanical Power Correlates With Lung Inflammation Assessed by Positron-Emission Tomography in Experimental Acute Lung Injury in Pigs. Front Physiol 2021; 12:717266. [PMID: 34880770 PMCID: PMC8645956 DOI: 10.3389/fphys.2021.717266] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 10/20/2021] [Indexed: 12/16/2022] Open
Abstract
Background: Mechanical ventilation (MV) may initiate or worsen lung injury, so-called ventilator-induced lung injury (VILI). Although different mechanisms of VILI have been identified, research mainly focused on single ventilator parameters. The mechanical power (MP) summarizes the potentially damaging effects of different parameters in one single variable and has been shown to be associated with lung damage. However, to date, the association of MP with pulmonary neutrophilic inflammation, as assessed by positron-emission tomography (PET), has not been prospectively investigated in a model of clinically relevant ventilation settings yet. We hypothesized that the degree of neutrophilic inflammation correlates with MP. Methods: Eight female juvenile pigs were anesthetized and mechanically ventilated. Lung injury was induced by repetitive lung lavages followed by initial PET and computed tomography (CT) scans. Animals were then ventilated according to the acute respiratory distress syndrome (ARDS) network recommendations, using the lowest combinations of positive end-expiratory pressure and inspiratory oxygen fraction that allowed adequate oxygenation. Ventilator settings were checked and adjusted hourly. Physiological measurements were conducted every 6 h. Lung imaging was repeated 24 h after first PET/CT before animals were killed. Pulmonary neutrophilic inflammation was assessed by normalized uptake rate of 2-deoxy-2-[18F]fluoro-D-glucose (KiS), and its difference between the two PET/CT was calculated (ΔKiS). Lung aeration was assessed by lung CT scan. MP was calculated from the recorded pressure-volume curve. Statistics included the Wilcoxon tests and non-parametric Spearman correlation. Results: Normalized 18F-FDG uptake rate increased significantly from first to second PET/CT (p = 0.012). ΔKiS significantly correlated with median MP (ρ = 0.738, p = 0.037) and its elastic and resistive components, but neither with median peak, plateau, end-expiratory, driving, and transpulmonary driving pressures, nor respiratory rate (RR), elastance, or resistance. Lung mass and volume significantly decreased, whereas relative mass of hyper-aerated lung compartment increased after 24 h (p = 0.012, p = 0.036, and p = 0.025, respectively). Resistance and PaCO2 were significantly higher (p = 0.012 and p = 0.017, respectively), whereas RR, end-expiratory pressure, and MP were lower at 18 h compared to start of intervention. Conclusions: In this model of experimental acute lung injury in pigs, pulmonary neutrophilic inflammation evaluated by PET/CT increased after 24 h of MV, and correlated with MP.
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Affiliation(s)
- Martin Scharffenberg
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Jakob Wittenstein
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Xi Ran
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Department of Intensive Care, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, China
| | - Yingying Zhang
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Department of Anesthesiology, Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Anja Braune
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Raphael Theilen
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Lorenzo Maiello
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Anesthesia and Critical Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Genoa, Italy
| | - Giulia Benzi
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Department of Clinical and Biological Sciences, Service of Anesthesia and Intensive Care, Ospedale di Circolo e Fondazione Macchi, University of Insubria, Varese, Italy
| | - Thomas Bluth
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Thomas Kiss
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Department of Anaesthesiology, Intensive-, Pain- and Palliative Care Medicine, Radebeul Hospital, Academic Hospital of the Technische Universität Dresden, Radebeul, Germany
| | - Paolo Pelosi
- Anesthesia and Critical Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Genoa, Italy
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy
| | - Patricia R. M. Rocco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marcus J. Schultz
- Department of Intensive Care and Laboratory of Experimental Intensive Care and Anaesthesiology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Jörg Kotzerke
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Marcelo Gama de Abreu
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Department of Intensive Care and Resuscitation, Anesthesiology Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Robert Huhle
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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Oliveira LVF, Apostólico N, Uriarte JJ, da Palma RK, Prates RA, Deana AM, Ferreira LR, Afonso JPR, de Paula Vieira R, de Oliveira Júnior MC, Navajas D, Farré R, Lopes-Martins RAB. Photodynamic Therapy in the Extracellular Matrix of Mouse Lungs: Preliminary Results of an Alternative Tissue Sterilization Process. INTERNATIONAL JOURNAL OF PHOTOENERGY 2021; 2021:1-9. [DOI: 10.1155/2021/5578387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Lung transplantation is one of the most difficult and delicate procedures among organ transplants. For the success of the procedure and survival of the new organ, the sterilization step for acellular lungs prior to recellularization is important to ensure that they are free of any risk of transmitting infections from the donor to the recipient subject. However, there are no available information concerning the lung mechanical parameters after sterilizing photodynamic therapy. The aim of this study was to evaluate the extracellular matrix (ECM) and lung mechanical parameters of decellularized lungs undergoing sterilizing photodynamic therapy (PDT). Besides, we also analyzed the lung after controlled infection with C. albicans in order to evaluate the effectiveness of PDT. The lung mechanical evaluation parameters, resistance (
) and elastance (
), exhibited no significant differences between groups. In addition, there were no PDT-induced changes in lung properties, with maintenance of the viscoelastic behavior of the lung scaffold after 1 h exposure to PDT. The ECM components remained virtually unchanged in the acellular lungs of both groups. We also showed that there was a reduction in fungal infection population after 45 minutes of PDT. However, more studies should be performed to establish and verify the effectiveness of PDT as a possible means for sterilizing lung scaffolds. This manuscript was presented as a master thesis of Nadua Apostólico at the postgraduate program in rehabilitation sciences, University Nove de Julho—UNINOVE.
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Affiliation(s)
| | - Nadua Apostólico
- Rehabilitation Sciences, Nove de Julho University (UNINOVE), Sao Paulo, SP, Brazil
| | - Juan José Uriarte
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona (UB), Barcelona, Spain
| | - Renata Kelly da Palma
- Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, São Paulo, SP, Brazil
- Biomimetic Systems for Cell Engineering, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
| | - Renato A. Prates
- Master’s and Doctoral Degree Programs in Biophotonics Applied to Health Sciences, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil
| | - Alessandro Melo Deana
- Master’s and Doctoral Degree Programs in Biophotonics Applied to Health Sciences, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil
| | - Luis Rodolfo Ferreira
- Master’s and Doctoral Degree Programs in Biophotonics Applied to Health Sciences, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil
| | - João Pedro Ribeiro Afonso
- Human Movement and Rehabilitation (PPGMHR), University Center of Anápolis (UniEVANGÉLICA), Anápolis, GO, Brazil
| | - Rodolfo de Paula Vieira
- Postgraduate Program in Bioengineering, Universidade Brasil, São Paulo, SP, Brazil
- Brazilian Institute of Teaching and Research in Pulmonary and Exercise Immunology (IBEPIPE), São José dos Campos, SP, Brazil
| | | | - Daniel Navajas
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona (UB), Barcelona, Spain
| | - Ramon Farré
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona (UB), Barcelona, Spain
| | - Rodrigo Alvaro B. Lopes-Martins
- Human Movement and Rehabilitation (PPGMHR), University Center of Anápolis (UniEVANGÉLICA), Anápolis, GO, Brazil
- Postgraduate Program in Bioengineering, Universidade Brasil, São Paulo, SP, Brazil
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Effects of two stepwise lung recruitment strategies on respiratory function and haemodynamics in anaesthetised pigs: A randomised crossover study. Eur J Anaesthesiol 2021; 38:634-643. [PMID: 33967255 DOI: 10.1097/eja.0000000000001480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND Lung recruitment manoeuvres and positive end-expiratory pressure (PEEP) can improve lung function during general anaesthesia. Different recruitment manoeuvre strategies have been described in large international trials: in the protective ventilation using high vs. low PEEP (PROVHILO) strategy, tidal volume (VT) was increased during volume-controlled ventilation; in the individualised peri-operative open-lung approach vs. standard protective ventilation in abdominal surgery (iPROVE) strategy, PEEP was increased during pressure-controlled ventilation. OBJECTIVES To compare the effects of the PROVHILO strategy and the iPROVE strategy on respiratory and haemodynamic variables. DESIGN Randomised crossover study. SETTING University hospital research facility. ANIMALS A total of 20 juvenile anaesthetised pigs. INTERVENTIONS Animals were assigned randomly to one of two sequences: PROVHILO strategy followed by iPROVE strategy or vice-versa (n = 10/sequence). In the PROVHILO strategy, VT was increased stepwise by 4 ml kg-1 at a fixed PEEP of 12 cmH2O until a plateau pressure of 30 to 35 cmH2O was reached. In the iPROVE strategy, at fixed driving pressure of 20 cmH2O, PEEP was increased up to 20 cmH2O followed by PEEP titration according to the lowest elastance of the respiratory system (ERS). MAIN OUTCOME MEASURES We assessed regional transpulmonary pressure (Ptrans), respiratory system mechanics, gas exchange and haemodynamics, as well as the centre of ventilation (CoV) by electrical impedance tomography. RESULTS During recruitment manoeuvres with the PROVHILO strategy compared with the iPROV strategy, dorsal Ptrans was lower at end-inspiration (16.3 ± 2.7 vs. 18.6 ± 3.1 cmH2O, P = 0.001) and end-expiration (4.8 ± 2.6 vs. 8.8 ± 3.4 cmH2O, P < 0.001), and mean arterial pressure (MAP) was higher (77 ± 11 vs. 60 ± 14 mmHg, P < 0.001). At 1 and 15 min after recruitment manoeuvres, ERS was higher in the PROVHILO strategy than the iPROVE strategy (24.6 ± 3.9 vs. 21.5 ± 3.4 and 26.7 ± 4.3 vs. 24.0 ± 3.8 cmH2O l-1; P < 0.001, respectively). At 1 min, PaO2 was lower in PROVHILO compared with iPROVE strategy (57.1 ± 6.1 vs. 59.3 ± 5.1 kPa, P = 0.013), but at 15 min, values did not differ. CoV did not differ between strategies. CONCLUSION In anaesthetised pigs, the iPROVE strategy compared with the PROVHILO strategy increased dorsal Ptrans at the cost of lower MAP during recruitment manoeuvres, and decreased ERS thereafter, without consistent improvement of oxygenation or shift of the CoV. TRIAL REGISTRATION This study was registered and approved by the Landesdirektion Dresden, Germany (DD24-5131/338/28).
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Scharffenberg M, Wittenstein J, Herzog M, Tauer S, Vivona L, Theilen R, Bluth T, Kiss T, Koch T, Fiorentino G, de Abreu MG, Huhle R. Continuous external negative pressure improves oxygenation and respiratory mechanics in Experimental Lung Injury in Pigs - A pilot proof-of-concept trial. Intensive Care Med Exp 2020; 8:49. [PMID: 33336263 PMCID: PMC7746426 DOI: 10.1186/s40635-020-00315-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 11/10/2022] Open
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.
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Affiliation(s)
- Martin Scharffenberg
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Jakob Wittenstein
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Moritz Herzog
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Sebastian Tauer
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Luigi Vivona
- Department of Pathophysiology and Transplantation, University of Milan, Via Francesco Sforza 35, 20122, Milano, Italia
| | - Raphael Theilen
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Thomas Bluth
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Thomas Kiss
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Thea Koch
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | | | - Marcelo Gama de Abreu
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Robert Huhle
- Pulmonary Engineering Group, Dept. of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus at Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany.
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9
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Cereda M, Xin Y, Goffi A, Herrmann J, Kaczka DW, Kavanagh BP, Perchiazzi G, Yoshida T, Rizi RR. Imaging the Injured Lung: Mechanisms of Action and Clinical Use. Anesthesiology 2019; 131:716-749. [PMID: 30664057 PMCID: PMC6692186 DOI: 10.1097/aln.0000000000002583] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Acute respiratory distress syndrome (ARDS) consists of acute hypoxemic respiratory failure characterized by massive and heterogeneously distributed loss of lung aeration caused by diffuse inflammation and edema present in interstitial and alveolar spaces. It is defined by consensus criteria, which include diffuse infiltrates on chest imaging-either plain radiography or computed tomography. This review will summarize how imaging sciences can inform modern respiratory management of ARDS and continue to increase the understanding of the acutely injured lung. This review also describes newer imaging methodologies that are likely to inform future clinical decision-making and potentially improve outcome. For each imaging modality, this review systematically describes the underlying principles, technology involved, measurements obtained, insights gained by the technique, emerging approaches, limitations, and future developments. Finally, integrated approaches are considered whereby multimodal imaging may impact management of ARDS.
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Affiliation(s)
- Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Alberto Goffi
- Interdepartmental Division of Critical Care Medicine and Department of Medicine, University of Toronto, ON, Canada
| | - Jacob Herrmann
- Departments of Anesthesia and Biomedical Engineering, University of Iowa, IA
| | - David W. Kaczka
- Departments of Anesthesia, Radiology, and Biomedical Engineering, University of Iowa, IA
| | | | - Gaetano Perchiazzi
- Hedenstierna Laboratory and Uppsala University Hospital, Uppsala University, Sweden
| | - Takeshi Yoshida
- Hospital for Sick Children, University of Toronto, ON, Canada
| | - Rahim R. Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
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10
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Ruiz Ferrón F, Serrano Simón J. La monitorización convencional no es suficiente para valorar el esfuerzo respiratorio durante la ventilación asistida. Med Intensiva 2019; 43:197-206. [DOI: 10.1016/j.medin.2018.02.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 01/25/2018] [Accepted: 02/14/2018] [Indexed: 12/28/2022]
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11
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Victor M, Melo J, Roldán R, Nakamura M, Tucci M, Costa E, Amato M, Yoneyama T, Tanaka H. Modelling approach to obtain regional respiratory mechanics using electrical impedance tomography and volume-dependent elastance model. Physiol Meas 2019; 40:045001. [PMID: 30921784 DOI: 10.1088/1361-6579/ab144a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE This paper presents a method for breath-by-breath estimation of regional respiratory mechanics without the need for special manoeuvres (such as inspiratory pause or low-flow inflation) using electrical impedance tomography (EIT) associated with pressure/airflow waveforms. APPROACH We developed a method to estimate regional parameters using the regional impedance fraction, by multiplying it by global flow and volume waveforms. A volume-dependent elastance model was used to obtain compliance, resistance, volume-independent (E 1), and volume-dependent (E 2) components. Three swine under invasive mechanical ventilation were used to assess internal consistency and illustrate potential applications of our method. One animal (case 1) was ventilated with a broad range of tidal volumes to compare the consistency between regional and global resistances and compliances. Two other animals (cases 2 and 3) had respiratory compliance decreased, respectively, by overdistension and collapse as quantified by x-ray computed tomography. MAIN RESULTS In case 1, derived global estimates obtained from the independent regional estimates were strongly associated with direct measurements of global mechanics (correlation coefficients of 0.9976 and 0.9981 for compliances and resistances, respectively), suggesting consistency of our modelling. In cases 2 and 3, the development of lung overdistension and collapse over time was captured by regional estimates. CONCLUSIONS Using EIT and pressure/airflow waveforms, regional respiratory parameters can be obtained cycle-by-cycle, refining lung function monitoring. SIGNIFICANCE The method allows real-time monitoring of regional parameters and their trends over time, which might be helpful to differentiate deterioration in lung compliance due to overdistension or collapse.
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Affiliation(s)
- M Victor
- Electronics Engineering Department, Aeronautics Institute of Technology, São Paulo, Brazil
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12
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Güldner A, Huhle R, Beda A, Kiss T, Bluth T, Rentzsch I, Kerber S, Carvalho NC, Kasper M, Pelosi P, de Abreu MG. Periodic Fluctuation of Tidal Volumes Further Improves Variable Ventilation in Experimental Acute Respiratory Distress Syndrome. Front Physiol 2018; 9:905. [PMID: 30050467 PMCID: PMC6052143 DOI: 10.3389/fphys.2018.00905] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 06/21/2018] [Indexed: 11/28/2022] Open
Abstract
In experimental acute respiratory distress syndrome (ARDS), random variation of tidal volumes (VT) during volume controlled ventilation improves gas exchange and respiratory system mechanics (so-called stochastic resonance hypothesis). It is unknown whether those positive effects may be further enhanced by periodic VT fluctuation at distinct frequencies, also known as deterministic frequency resonance. We hypothesized that the positive effects of variable ventilation on lung function may be further amplified by periodic VT fluctuation at specific frequencies. In anesthetized and mechanically ventilated pigs, severe ARDS was induced by saline lung lavage and injurious VT (double-hit model). Animals were then randomly assigned to 6 h of protective ventilation with one of four VT patterns: (1) random variation of VT (WN); (2) P04, main VT frequency of 0.13 Hz; (3) P10, main VT frequency of 0.05 Hz; (4) VCV, conventional non-variable volume controlled ventilation. In groups with variable VT, the coefficient of variation was identical (30%). We assessed lung mechanics and gas exchange, and determined lung histology and inflammation. Compared to VCV, WN, P04, and P10 resulted in lower respiratory system elastance (63 ± 13 cm H2O/L vs. 50 ± 14 cm H2O/L, 48.4 ± 21 cm H2O/L, and 45.1 ± 5.9 cm H2O/L respectively, P < 0.05 all), but only P10 improved PaO2/FIO2 after 6 h of ventilation (318 ± 96 vs. 445 ± 110 mm Hg, P < 0.05). Cycle-by-cycle analysis of lung mechanics suggested intertidal recruitment/de-recruitment in P10. Lung histologic damage and inflammation did not differ among groups. In this experimental model of severe ARDS, periodic VT fluctuation at a frequency of 0.05 Hz improved oxygenation during variable ventilation, suggesting that deterministic resonance adds further benefit to variable ventilation.
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Affiliation(s)
- Andreas Güldner
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Robert Huhle
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Alessandro Beda
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Departamento de Engenharia Eletrônica, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Thomas Kiss
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Thomas Bluth
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Ines Rentzsch
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Department of Orthodontics, Technische Universität Dresden, Dresden, Germany
| | - Sarah Kerber
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Nadja C Carvalho
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Departamento de Engenharia Eletrônica, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Michael Kasper
- Institute of Anatomy, Technische Universität Dresden, Dresden, Germany
| | - Paolo Pelosi
- Department of Surgical Sciences and Integrated Diagnostics, IRCCS San Martino IST, University of Genoa, Genoa, Italy
| | - Marcelo G de Abreu
- Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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13
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Soares JHN, Carvalho AR, Bergamini BC, Gress MAK, Jandre FC, Zin WA, Giannella-Neto A. Alveolar Tidal recruitment/derecruitment and Overdistension During Four Levels of End-Expiratory Pressure with Protective Tidal Volume During Anesthesia in a Murine Lung-Healthy Model. Lung 2018; 196:335-342. [DOI: 10.1007/s00408-018-0096-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 02/05/2018] [Indexed: 12/16/2022]
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14
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Respiratory System Mechanics During Low Versus High Positive End-Expiratory Pressure in Open Abdominal Surgery: A Substudy of PROVHILO Randomized Controlled Trial. Anesth Analg 2018. [PMID: 28632529 DOI: 10.1213/ane.0000000000002192] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND In the 2014 PROtective Ventilation using HIgh versus LOw positive end-expiratory pressure (PROVHILO) trial, intraoperative low tidal volume ventilation with high positive end-expiratory pressure (PEEP = 12 cm H2O) and lung recruitment maneuvers did not decrease postoperative pulmonary complications when compared to low PEEP (0-2 cm H2O) approach without recruitment breaths. However, effects of intraoperative PEEP on lung compliance remain poorly understood. We hypothesized that higher PEEP leads to a dominance of intratidal overdistension, whereas lower PEEP results in intratidal recruitment/derecruitment (R/D). To test our hypothesis, we used the volume-dependent elastance index %E2, a respiratory parameter that allows for noninvasive and radiation-free assessment of dominant overdistension and intratidal R/D. We compared the incidence of intratidal R/D, linear expansion, and overdistension by means of %E2 in a subset of the PROVHILO cohort. METHODS In 36 patients from 2 participating centers of the PROVHILO trial, we calculated respiratory system elastance (E), resistance (R), and %E2, a surrogate parameter for intratidal overdistension (%E2 > 30%) and R/D (%E2 < 0%). To test the main hypothesis, we compared the incidence of intratidal overdistension (primary end point) and R/D in higher and lower PEEP groups, as measured by %E2. RESULTS E was increased in the lower compared to higher PEEP group (18.6 [16…22] vs 13.4 [11.0…17.0] cm H2O·L; P < .01). %E2 was reduced in the lower PEEP group compared to higher PEEP (-15.4 [-28.0…6.5] vs 6.2 [-0.8…14.0] %; P < .05). Intratidal R/D was increased in the lower PEEP group (61% vs 22%; P = .037). The incidence of intratidal overdistension did not differ significantly between groups (6%). CONCLUSIONS During mechanical ventilation with protective tidal volumes in patients undergoing open abdominal surgery, lung recruitment followed by PEEP of 12 cm H2O decreased the incidence of intratidal R/D and did not worsen overdistension, when compared to PEEP ≤2 cm H2O.
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15
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Soluri-Martins A, Moraes L, Santos RS, Santos CL, Huhle R, Capelozzi VL, Pelosi P, Silva PL, de Abreu MG, Rocco PRM. Variable Ventilation Improved Respiratory System Mechanics and Ameliorated Pulmonary Damage in a Rat Model of Lung Ischemia-Reperfusion. Front Physiol 2017; 8:257. [PMID: 28512431 PMCID: PMC5411427 DOI: 10.3389/fphys.2017.00257] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/10/2017] [Indexed: 12/28/2022] Open
Abstract
Lung ischemia-reperfusion injury remains a major complication after lung transplantation. Variable ventilation (VV) has been shown to improve respiratory function and reduce pulmonary histological damage compared to protective volume-controlled ventilation (VCV) in different models of lung injury induced by endotoxin, surfactant depletion by saline lavage, and hydrochloric acid. However, no study has compared the biological impact of VV vs. VCV in lung ischemia-reperfusion injury, which has a complex pathophysiology different from that of other experimental models. Thirty-six animals were randomly assigned to one of two groups: (1) ischemia-reperfusion (IR), in which the left pulmonary hilum was completely occluded and released after 30 min; and (2) Sham, in which animals underwent the same surgical manipulation but without hilar clamping. Immediately after surgery, the left (IR-injured) and right (contralateral) lungs from 6 animals per group were removed, and served as non-ventilated group (NV) for molecular biology analysis. IR and Sham groups were further randomized to one of two ventilation strategies: VCV (n = 6/group) [tidal volume (VT) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 2 cmH2O, fraction of inspired oxygen (FiO2) = 0.4]; or VV, which was applied on a breath-to-breath basis as a sequence of randomly generated VT values (n = 1200; mean VT = 6 mL/kg), with a 30% coefficient of variation. After 5 min of ventilation and at the end of a 2-h period (Final), respiratory system mechanics and arterial blood gases were measured. At Final, lungs were removed for histological and molecular biology analyses. Respiratory system elastance and alveolar collapse were lower in VCV than VV (mean ± SD, VCV 3.6 ± 1.3 cmH20/ml and 2.0 ± 0.8 cmH20/ml, p = 0.005; median [interquartile range], VCV 20.4% [7.9–33.1] and VV 5.4% [3.1–8.8], p = 0.04, respectively). In left lungs of IR animals, VCV increased the expression of interleukin-6 and intercellular adhesion molecule-1 compared to NV, with no significant differences between VV and NV. Compared to VCV, VV increased the expression of surfactant protein-D, suggesting protection from type II epithelial cell damage. In conclusion, in this experimental lung ischemia-reperfusion model, VV improved respiratory system elastance and reduced lung damage compared to VCV.
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Affiliation(s)
- André Soluri-Martins
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Lillian Moraes
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Raquel S Santos
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Cintia L Santos
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Robert Huhle
- Pulmonary Engineering Group, Department of Anesthesiology and Intensive Care Therapy, University Hospital Carl Gustav Carus, Dresden University of TechnologyDresden, Germany
| | - Vera L Capelozzi
- Department of Pathology, School of Medicine, University of São PauloSão Paulo, Brazil
| | - Paolo Pelosi
- Department of Surgical Sciences and Integrated Diagnostics, University of GenoaGenoa, Italy
| | - Pedro L Silva
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Marcelo Gama de Abreu
- Pulmonary Engineering Group, Department of Anesthesiology and Intensive Care Therapy, University Hospital Carl Gustav Carus, Dresden University of TechnologyDresden, Germany
| | - Patricia R M Rocco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de JaneiroRio de Janeiro, Brazil
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16
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Mapping Regional Differences of Local Pressure-Volume Curves With Electrical Impedance Tomography. Crit Care Med 2017; 45:679-686. [DOI: 10.1097/ccm.0000000000002233] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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17
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Perchiazzi G, Rylander C, Pellegrini M, Larsson A, Hedenstierna G. Robustness of two different methods of monitoring respiratory system compliance during mechanical ventilation. Med Biol Eng Comput 2017; 55:1819-1828. [PMID: 28243966 PMCID: PMC5603635 DOI: 10.1007/s11517-017-1631-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 02/18/2017] [Indexed: 11/24/2022]
Abstract
Robustness measures the performance of estimation methods when they work under non-ideal conditions. We compared the robustness of artificial neural networks (ANNs) and multilinear fitting (MLF) methods in estimating respiratory system compliance (CRS) during mechanical ventilation (MV). Twenty-four anaesthetized pigs underwent MV. Airway pressure, flow and volume were recorded at fixed intervals after the induction of acute lung injury. After consecutive mechanical breaths, an inspiratory pause (BIP) was applied in order to calculate CRS using the interrupter technique. From the breath preceding the BIP, ANN and MLF had to compute CRS in the presence of two types of perturbations: transient sensor disconnection (TD) and random noise (RN). Performance of the two methods was assessed according to Bland and Altman. The ANN presented a higher bias and scatter than MLF during the application of RN, except when RN was lower than 2% of peak airway pressure. During TD, MLF algorithm showed a higher bias and scatter than ANN. After the application of RN, ANN and MLF maintain a stable performance, although MLF shows better results. ANNs have a more stable performance and yield a more robust estimation of CRS than MLF in conditions of transient sensor disconnection.
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Affiliation(s)
- Gaetano Perchiazzi
- Department of Emergency and Organ Transplant, Bari University, Bari, Italy. .,Hedenstierna Laboratory, Surgical Sciences, Uppsala University, Akademiska Sjukhuset ing.40 tr.3, 75185, Uppsala, Sweden.
| | - Christian Rylander
- Department of Anaesthesia and Intensive Care Medicine, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Mariangela Pellegrini
- Department of Emergency and Organ Transplant, Bari University, Bari, Italy.,Hedenstierna Laboratory, Surgical Sciences, Uppsala University, Akademiska Sjukhuset ing.40 tr.3, 75185, Uppsala, Sweden
| | - Anders Larsson
- Hedenstierna Laboratory, Surgical Sciences, Uppsala University, Akademiska Sjukhuset ing.40 tr.3, 75185, Uppsala, Sweden
| | - Göran Hedenstierna
- Hedenstierna Laboratory, Medical Sciences, Uppsala University, Uppsala, Sweden
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18
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Henriques I, Padilha GA, Huhle R, Wierzchon C, Miranda PJB, Ramos IP, Rocha N, Cruz FF, Santos RS, de Oliveira MV, Souza SA, Goldenberg RC, Luiz RR, Pelosi P, de Abreu MG, Silva PL, Rocco PRM. Comparison between Variable and Conventional Volume-Controlled Ventilation on Cardiorespiratory Parameters in Experimental Emphysema. Front Physiol 2016; 7:277. [PMID: 27445862 PMCID: PMC4928149 DOI: 10.3389/fphys.2016.00277] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/20/2016] [Indexed: 01/13/2023] Open
Abstract
Emphysema is characterized by loss of lung tissue elasticity and destruction of structures supporting alveoli and capillaries. The impact of mechanical ventilation strategies on ventilator-induced lung injury (VILI) in emphysema is poorly defined. New ventilator strategies should be developed to minimize VILI in emphysema. The present study was divided into two protocols: (1) characterization of an elastase-induced emphysema model in rats and identification of the time point of greatest cardiorespiratory impairment, defined as a high specific lung elastance associated with large right ventricular end-diastolic area; and (2) comparison between variable (VV) and conventional volume-controlled ventilation (VCV) on lung mechanics and morphometry, biological markers, and cardiac function at that time point. In the first protocol, Wistar rats (n = 62) received saline (SAL) or porcine pancreatic elastase (ELA) intratracheally once weekly for 4 weeks, respectively. Evaluations were performed 1, 3, 5, or 8 weeks after the last intratracheal instillation of saline or elastase. After identifying the time point of greatest cardiorespiratory impairment, an additional 32 Wistar rats were randomized into the SAL and ELA groups and then ventilated with VV or VCV (n = 8/group) [tidal volume (VT) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 3 cmH2O, fraction of inspired oxygen (FiO2) = 0.4] for 2 h. VV was applied on a breath-to-breath basis as a sequence of randomly generated VT values (mean VT = 6 mL/kg), with a 30% coefficient of variation. Non-ventilated (NV) SAL and ELA animals were used for molecular biology analysis. The time point of greatest cardiorespiratory impairment, was observed 5 weeks after the last elastase instillation. At this time point, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC)-1, amphiregulin, angiopoietin (Ang)-2, and vascular endothelial growth factor (VEGF) mRNA levels were higher in ELA compared to SAL. In ELA animals, VV reduced respiratory system elastance, alveolar collapse, and hyperinflation compared to VCV, without significant differences in gas exchange, but increased right ventricular diastolic area. Interleukin-6 mRNA expression was higher in VCV and VV than NV, while surfactant protein-D was increased in VV compared to NV. In conclusion, VV improved lung function and morphology and reduced VILI, but impaired right cardiac function in this model of elastase induced-emphysema.
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Affiliation(s)
- Isabela Henriques
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Gisele A Padilha
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Robert Huhle
- Pulmonary Engineering Group, Department of Anesthesiology and Intensive Care Therapy, University Hospital Carl Gustav Carus, Technische Universität Dresden Dresden, Germany
| | - Caio Wierzchon
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Paulo J B Miranda
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Isalira P Ramos
- Laboratory of Molecular and Cellular Cardiology, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de JaneiroRio de Janeiro, Brazil; National Center for Structural Biology and Bioimaging, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Nazareth Rocha
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de JaneiroRio de Janeiro, Brazil; Department of Physiology and Pharmacology, Biomedical Institute, Fluminense Federal UniversityNiterói, Brazil
| | - Fernanda F Cruz
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Raquel S Santos
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Milena V de Oliveira
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Sergio A Souza
- National Center for Structural Biology and Bioimaging, Federal University of Rio de JaneiroRio de Janeiro, Brazil; Nuclear Medicine Service, Clementino Fraga Filho University Hospital, Federal University of Rio de JaneiroRio de Janeiro, Brazil
| | - Regina C Goldenberg
- Laboratory of Molecular and Cellular Cardiology, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Ronir R Luiz
- Institute of Public Health Studies, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Paolo Pelosi
- Department of Surgical Sciences and Integrated Diagnostics, IRCCS AOU San Martino IST, University of Genoa Genoa, Italy
| | - Marcelo G de Abreu
- Pulmonary Engineering Group, Department of Anesthesiology and Intensive Care Therapy, University Hospital Carl Gustav Carus, Technische Universität Dresden Dresden, Germany
| | - Pedro L Silva
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
| | - Patricia R M Rocco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro Rio de Janeiro, Brazil
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Amini R, Herrmann J, Kaczka DW. Intratidal Overdistention and Derecruitment in the Injured Lung: A Simulation Study. IEEE Trans Biomed Eng 2016; 64:681-689. [PMID: 27244715 DOI: 10.1109/tbme.2016.2572678] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
GOAL Ventilated patients with the acute respiratory distress syndrome (ARDS) are predisposed to cyclic parenchymal overdistention and derecruitment, which may worsen existing injury. We hypothesized that intratidal variations in global mechanics, as assessed at the airway opening, would reflect such distributed processes. METHODS We developed a computational lung model for determining local instantaneous pressure distributions and mechanical impedances continuously during a breath. Based on these distributions and previous literature, we simulated the within-breath variability of airway segment dimensions, parenchymal viscoelasticity, and acinar recruitment in an injured canine lung for tidal volumes( VT ) of 10, 15, and 20 mL·kg-1 and positive end-expiratory pressures (PEEP) of 5, 10, and 15 cm H2O. Acini were allowed to transition between recruited and derecruited states when exposed to stochastically determined critical opening and closing pressures, respectively. RESULTS For conditions of low VT and low PEEP, we observed small intratidal variations in global resistance and elastance, with a small number of cyclically recruited acini. However, with higher VT and PEEP, larger variations in resistance and elastance were observed, and the majority of acini remained open throughout the breath. Changes in intratidal resistance, elastance, and impedance followed well-defined parabolic trajectories with tracheal pressure, achieving minima near 12 to 16 cm H2O. CONCLUSION Intratidal variations in lung mechanics may allow for optimization of ventilator settings in patients with ARDS, by balancing lung recruitment against parenchymal overdistention. SIGNIFICANCE Titration of airway pressures based on variations in intratidal mechanics may mitigate processes associated with injurious ventilation.
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Hutchison AA, Leclerc F, Nève V, Pillow JJ, Robinson PD. The Respiratory System. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7193717 DOI: 10.1007/978-3-642-01219-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This chapter addresses upper airway physiology for the pediatric intensivist, focusing on functions that affect ventilation, with an emphasis on laryngeal physiology and control in breathing. Effective control of breathing ensures that the airway is protected, maintains volume homeostasis, and provides ventilation. Upper airway structures are effectors for all of these functions that affect the entire airway. Nasal functions include air conditioning and protective reflexes that can be exaggerated and involve circulatory changes. Oral cavity and pharyngeal patency enable airflow and feeding, but during sleep pharyngeal closure can result in apnea. Coordination of breathing with sucking and nutritive swallowing alters during development, while nonnutritive swallowing at all ages limits aspiration. Laryngeal functions in breathing include protection of the subglottic airway, active maintenance of its absolute volume, and control of tidal flow patterns. These are vital functions for normal lung growth in fetal life and during rapid adaptations to breathing challenges from birth through adulthood. Active central control of breathing focuses on the coordination of laryngeal and diaphragmatic activities, which adapts according to the integration of central and peripheral inputs. For the intensivist, knowledge of upper airway physiology can be applied to improve respiratory support. In a second part the mechanical properties of the respiratory system as a critical component of the chain of events that result in translation of the output of the respiratory rhythm generator to ventilation are described. A comprehensive understanding of respiratory mechanics is essential to the delivery of optimized and individualized mechanical ventilation. The basic elements of respiratory mechanics will be described and developmental changes in the airways, lungs, and chest wall that impact on measurement of respiratory mechanics with advancing postnatal age are reviewed. This will be follwowed by two sections, the first on respiratory mechanics in various neonatal pathologies and the second in pediatric pathologies. The latter can be classified in three categories. First, restrictive diseases may be of pulmonary origin, such as chronic interstitial lung diseases or acute lung injury/acute respiratory distress syndrome, which are usually associated with reduced lung compliance. Restrictive diseases may also be due to chest wall abnormalities such as obesity or scoliosis (idiopathic or secondary to neuromuscular diseases), which are associated with a reduction in chest wall compliance. Second, obstructive diseases are represented by asthma and wheezing disorders, cystic fibrosis, long term sequelae of neonatal lung disease and bronchiolitis obliterans following hematopoietic stem cell transplantation. Obstructive diseases are defined by a reduced FEV1/VC ratio. Third, neuromuscular diseases, mainly represented by DMD and SMA, are associated with a decrease in vital capacity linked to respiratory muscle weakness that is better detected by PImax, PEmax and SNIP measurements.
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Carvalho AR, Bergamini BC, Carvalho NS, Cagido VR, Neto AC, Jandre FC, Zin WA, Giannella-Neto A. Volume-Independent Elastance. Anesth Analg 2013; 116:627-33. [DOI: 10.1213/ane.0b013e31824a95ca] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Zhao Z, Guttmann J, Möller K. Assessment of a volume-dependent dynamic respiratory system compliance in ALI/ARDS by pooling breathing cycles. Physiol Meas 2012; 33:N61-7. [PMID: 22828159 DOI: 10.1088/0967-3334/33/8/n61] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
New methods were developed to calculate the volume-dependent dynamic respiratory system compliance (C(rs)) in mechanically ventilated patients. Due to noise in respiratory signals and different characteristics of the methods, their results can considerably differ. The aim of the study was to establish a practical procedure to validate the estimation of intratidal dynamic C(rs). A total of 28 patients from intensive care units of eight German university hospitals with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) were studied retrospectively. Dynamic volume-dependent C(rs) was determined during ongoing mechanical ventilation with the SLICE method, dynostatic algorithm and adaptive slice method. Conventional two-point compliance C(2P) was calculated for comparison. A number of consecutive breathing cycles were pooled to reduce noise in the respiratory signals. C(rs)-volume curves produced with different methods converged when the number of pooling cycles increased (n ≥ 7). The mean volume-dependent C(rs) of 20 breaths was highly correlated with mean C(2P) (C(2P,mean) = 0.945 × C(rs,mean) - 0.053, r(2) = 0.968, p < 0.0001). The Bland-Altman analysis indicated that C(2P,mean) was lower than C(rs,mean) (-2.4 ± 6.4 ml cm(-1) H(2)O, mean bias ± 2 SD), but not significant according to the paired t-test (p > 0.05). Methods for analyzing dynamic respiratory mechanics are sensitive to noise and will converge to a unique solution when the number of pooled cycles increases. Under steady-state conditions, assessment of the volume-dependent C(rs) in ALI/ARDS patients can be validated by pooling respiratory data of consecutive breaths regardless of which method is applied. Confidence in dynamic C(rs) determination may be increased with the proposed pooling.
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Affiliation(s)
- Zhanqi Zhao
- Department of Biomedical Engineering, Furtwangen University, Jakob-Kienzle Strasse 17, D-78054, Villingen-Schwenningen, Germany.
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Detection of tidal recruitment/overdistension in lung-healthy mechanically ventilated patients under general anesthesia. Anesth Analg 2012; 116:677-84. [PMID: 22543064 DOI: 10.1213/ane.0b013e318254230b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The volume-dependent single compartment model (VDSCM) has been applied for identification of overdistension in mechanically ventilated patients with acute lung injury. In this observational study we evaluated the use of the VDSCM to identify tidal recruitment/overdistension induced by tidal volume (Vt) and positive end-expiratory pressure (PEEP) in lung-healthy anesthetized subjects. METHODS Fifteen patients (ASA physical status I-II) undergoing general anesthesia for elective plastic breast reconstruction surgery were mechanically ventilated in volume-controlled ventilation (VCV), with Vt of 8 mL•kg(-1) and PEEP of 0 cm H(2)O. With these settings, ventilatory mode was randomly adjusted in VCV or pressure-controlled ventilation (PCV) and PEEP was sequentially increased from 0 to 5 and 10 cm H(2)O, 5 min per step. Thereafter, PEEP was decreased to 0 cm H(2)O, Vt increased to 10 mL•kg(-1) and, keeping minute ventilation constant, PEEP was similarly increased to 5 and 10 cm H(2)O. Airway pressure and flow were continuously recorded and fitted to the VDSCM with or without considering flow-dependencies. A "distension index" (%E(2)) derived from the VDSCM was used to assess Vt and PEEP-induced recruitment/overdistension. Positive and negative values of %E(2) suggest tidal overdistension or tidal recruitment, respectively. In addition, the linear respiratory system elastance was calculated. Comparisons among variables at each PEEP value, Vt setting, ventilatory mode, and regression model considering or not considering flow-dependencies were performed with the Wilcoxon-sign rank test for paired samples (P < 0.05). Multiple comparisons were corrected with the Bonferroni method. The relative change in the estimated noisy variance was used as an index of the goodness of fit of the models. RESULTS VDSCM including the flow-dependent parameter significantly improved estimated noisy variance in almost all experimental conditions (11.2 to 71.4, smallest of the lower and highest of the upper 95% confidence intervals). No differences in %E(2) were observed between VCV and PCV, at comparable Vt and PEEP levels, when flow-dependencies were included in the regression model. The negligence of the flow-dependent parameter systematically led to an underestimation of %E(2) in PCV compared to VCV mode (all P < 0.02). At a given Vt, %E(2) was negative at a PEEP of 0 cm H(2)O and significantly increased with PEEP, being almost 0 at a PEEP of 5 cm H(2)O. At a given level of PEEP, %E(2) significantly increased with Vt. CONCLUSIONS The distension index %E(2), derived from the VDSCM considering flow-dependencies, seems able to identify tidal recruitment/overdistension induced by Vt and PEEP independent of flow waveform in healthy lung-anesthetized patients.
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Carvalho AR, Zin WA. Respiratory system dynamical mechanical properties: modeling in time and frequency domain. Biophys Rev 2011; 3:71. [PMID: 28510005 DOI: 10.1007/s12551-011-0048-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 05/03/2011] [Indexed: 11/30/2022] Open
Abstract
The mechanical properties of the respiratory system are important determinants of its function and can be severely compromised in disease. The assessment of respiratory system mechanical properties is thus essential in the management of some disorders as well as in the evaluation of respiratory system adaptations in response to an acute or chronic process. Most often, lungs and chest wall are treated as a linear dynamic system that can be expressed with differential equations, allowing determination of the system's parameters, which will reflect the mechanical properties. However, different models that encompass nonlinear characteristics and also multicompartments have been used in several approaches and most specifically in mechanically ventilated patients with acute lung injury. Additionally, the input impedance over a range of frequencies can be assessed with a convenient excitation method allowing the identification of the mechanical characteristics of the central and peripheral airways as well as lung periphery impedance. With the evolution of computational power, the airway pressure and flow can be recorded and stored for hours, and hence continuous monitoring of the respiratory system mechanical properties is already available in some mechanical ventilators. This review aims to describe some of the most frequently used models for the assessment of the respiratory system mechanical properties in both time and frequency domain.
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Affiliation(s)
- Alysson Roncally Carvalho
- Laboratory of Respiration Physiology, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Ilha do Fundão, 21941-902, Rio de Janeiro, RJ, Brazil
| | - Walter Araujo Zin
- Laboratory of Respiration Physiology, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Ilha do Fundão, 21941-902, Rio de Janeiro, RJ, Brazil.
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Optimisation of positive end-expiratory pressure by forced oscillation technique in a lavage model of acute lung injury. Intensive Care Med 2011; 37:1021-30. [DOI: 10.1007/s00134-011-2211-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 02/10/2011] [Indexed: 10/18/2022]
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Polak AG. Analysis of multiple linear regression algorithms used for respiratory mechanics monitoring during artificial ventilation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2011; 101:126-134. [PMID: 20822825 DOI: 10.1016/j.cmpb.2010.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 07/28/2010] [Accepted: 08/03/2010] [Indexed: 05/29/2023]
Abstract
Many patients undergo long-term artificial ventilation and their respiratory system mechanics should be monitored to detect changes in the patient's state and to optimize ventilator settings. In this work the most popular algorithms for tracking variations of respiratory resistance (R(rs)) and elastance (E(rs)) over a ventilatory cycle were analysed in terms of systematic and random errors. Additionally, a new approach was proposed and compared to the previous ones. It takes into account an exact description of flow integration by volume-dependent lung compliance. The results of analyses showed advantages of this new approach and enabled to form several suggestions. Algorithms including R(rs) and E(rs) dependencies on airflow and lung volume can be effectively applied only at low levels of noise present in measurement data, otherwise the use of the simplest model with constant parameters is preferable. Additionally, one should avoid including the resistance dependence on airflow alone, since this considerably destroys the retrieved trace of R(rs). Finally, the estimated cyclic trajectories of R(rs) and E(rs) are more sensitive to noise present in pressure than in the flow signal, and the elastance traces are estimated more accurately than the resistance ones.
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Affiliation(s)
- Adam G Polak
- Chair of Electronic and Photonic Metrology, Wrocław University of Technology, ul. B. Prusa 53/55, 50-317 Wrocław, Poland.
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On-line monitoring of lung mechanics during spontaneous breathing: a physiological study. Respir Med 2010; 104:463-71. [DOI: 10.1016/j.rmed.2009.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 09/20/2009] [Accepted: 09/22/2009] [Indexed: 11/17/2022]
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Carvalho AR, Spieth PM, Pelosi P, Vidal Melo MF, Koch T, Jandre FC, Giannella-Neto A, de Abreu MG. Ability of dynamic airway pressure curve profile and elastance for positive end-expiratory pressure titration. Intensive Care Med 2008; 34:2291-9. [PMID: 18825365 DOI: 10.1007/s00134-008-1301-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Accepted: 09/08/2008] [Indexed: 02/04/2023]
Abstract
OBJECTIVE To evaluate the ability of three indices derived from the airway pressure curve for titrating positive end-expiratory pressure (PEEP) to minimize mechanical stress while improving lung aeration assessed by computed tomography (CT). DESIGN Prospective, experimental study. SETTING University research facilities. SUBJECTS Twelve pigs. INTERVENTIONS Animals were anesthetized and mechanically ventilated with tidal volume of 7 ml kg(-1). In non-injured lungs (n = 6), PEEP was set at 16 cmH(2)O and stepwise decreased until zero. Acute lung injury was then induced either with oleic acid (n = 6) or surfactant depletion (n = 6). A recruitment maneuver was performed, the PEEP set at 26 cmH(2)O and decreased stepwise until zero. CT scans were obtained at end-expiratory and end-inspiratory pauses. The elastance of the respiratory system (Ers), the stress index and the percentage of volume-dependent elastance (%E (2)) were estimated. MEASUREMENTS AND MAIN RESULTS In non-injured and injured lungs, the PEEP at which Ers was lowest (8-4 and 16-12 cmH(2)O, respectively) corresponded to the best compromise between recruitment/hyperinflation. In non-injured lungs, stress index and %E (2) correlated with tidal recruitment and hyperinflation. In injured lungs, stress index and %E (2) suggested overdistension at all PEEP levels, whereas the CT scans evidenced tidal recruitment and hyperinflation simultaneously. CONCLUSION During ventilation with low tidal volumes, Ers seems to be useful for guiding PEEP titration in non-injured and injured lungs, while stress index and %E (2) are useful in non-injured lungs only. Our results suggest that Ers can be superior to the stress index and %E (2) to guide PEEP titration in focal loss of lung aeration.
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Affiliation(s)
- Alysson R Carvalho
- Clinic of Anesthesiology and Intensive Care Therapy, Medical Faculty, University Hospital Carl Gustav Carus, Dresden, Germany
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Jandre FC, Modesto FC, Carvalho ARS, Giannella-Neto A. The endotracheal tube biases the estimates of pulmonary recruitment and overdistension. Med Biol Eng Comput 2007; 46:69-73. [DOI: 10.1007/s11517-007-0227-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Accepted: 07/01/2007] [Indexed: 11/27/2022]
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Yuta T, Chase JG, Shaw GM, Hann C. Dynamic models of ARDS lung mechanics for optimal patient ventilation. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2004:861-4. [PMID: 17271813 DOI: 10.1109/iembs.2004.1403294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Mechanical ventilation is often used to treat patients with acute respiratory distress syndrome (ARDS). However, the optimal setting is still controversial, and physicians often rely on experience and intuition. The purpose of this research is to develop a model of the essential lung mechanics to help determining the optimal ventilator setting in clinical situations. The model is a compilation of physiologically based mechanics parameters, which are adjustable to represent patient specific conditions. Further investigation improvements are required, however it shows good initial for eventual clinical use.
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Affiliation(s)
- T Yuta
- Dept. of Mech. Eng., Canterbury Univ., Christchurch, New Zealand
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Jandre FC, Carvalho ARS, Pino AV, Giannella-Neto A. Effects of filtering and delays on the estimates of a nonlinear respiratory mechanics model. Respir Physiol Neurobiol 2005; 148:309-14. [PMID: 16143287 DOI: 10.1016/j.resp.2005.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 02/10/2005] [Accepted: 02/10/2005] [Indexed: 10/25/2022]
Abstract
Estimation of mechanical properties of the respiratory system may be disturbed by instrumentation and physical set-up. The effects of lowpass filtering, filter mismatch and inter-channel delay in the digital converter are assessed on numerically simulated signals from a nonlinear model of the respiratory system. Large biases in model parameter estimates (up to about -300% for some parameters) were caused by these instrumental interferences and were reduced by including an inertance in the retrieved model. The results reinforce the importance of a careful evaluation of the instrumental set-up used in physiological measurements.
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Affiliation(s)
- Frederico C Jandre
- Biomedical Engineering Programme, Federal University of Rio de Janeiro, Graduate School of Engineering, PO Box 68510, 21945-970 Rio de Janeiro, RJ, Brazil.
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Perchiazzi G, Giuliani R, Ruggiero L, Fiore T, Hedenstierna G. Estimating respiratory system compliance during mechanical ventilation using artificial neural networks. Anesth Analg 2003; 97:1143-1148. [PMID: 14500172 DOI: 10.1213/01.ane.0000077905.92474.82] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED In this study we evaluated whether a technology based on artificial neural networks (ANN) could estimate the static compliance (C(RS)) of the respiratory system, even in the absence of an end-inspiratory pause, during continuous mechanical ventilation. A porcine model of acute lung injury was used to provide recordings of different respiratory mechanics conditions. Each recording consisted of 10 or more consecutive breaths in volume-controlled mechanical ventilation, followed by a breath having an end-inspiratory pause used to calculate C(RS) according to the interrupter technique (IT). The volume-pressure loop of the breath immediately preceding the one with pause was given to the ANN for the training, together with the C(RS) separately calculated by the IT. The prospective phase consisted of giving only the loops to the trained ANN and comparing the results yielded by it to the compliance separately calculated by the investigators. Determination of measurement agreement between ANN and IT methods showed an error of -0.67 +/- 1.52 mL/cm H(2)O (bias +/- SD). We could conclude that ANN, during volume-controlled mechanical ventilation, can extract C(RS) without needing to stop inspiratory flow. IMPLICATIONS We studied the application of artificial neural networks (ANN) to the estimation of respiratory compliance during mechanical ventilation. The study was performed on an animal model of acute lung injury, testing the performance of ANN in both healthy and diseased conditions of the lung.
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Affiliation(s)
- Gaetano Perchiazzi
- *Department of Clinical Physiology, Uppsala University Hospital, Sweden; and †Department of Emergency and Transplantation, Bari University Hospital, Italy
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Eberhard A, Carry PY, Perdrix JP, Fargnoli JM, Biot L, Baconnier PF. A program based on a 'selective' least-squares method for respiratory mechanics monitoring in ventilated patients. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2003; 71:39-61. [PMID: 12725964 DOI: 10.1016/s0169-2607(02)00030-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper proposes a program for continuous estimation of respiratory mechanics parameters in ventilated patients. This program can be used with any ventilator providing airway pressure and flow signals without additional equipment. Overall breathing resistance, dynamic elastance (E) and positive end expiratory pressure (P(0)) are periodically estimated by multiple linear regression on selected parts of breathing cycles. Experimental validation together with justification of the selection procedure are based on signals obtained while ventilating a lung mechanical analogue with various intensive care ventilators. Clinical validity has been tested on 12 ventilated patients. The quality of estimation has been assessed by mean square difference between measured and reconstituted pressure (MSE), coefficient of determination (R(2)) and the condition number (a confidence index), and by comparison of E and P(0) with corresponding static values. The high R(2) and the low MSE obtained on most clinical cycles indicate that selected parts of cycles obey closely the model underlying parameter estimation. Agreement between static and dynamic parameters demonstrates the clinical validity of our program.
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Affiliation(s)
- André Eberhard
- Laboratoire de Modélisation et Calcul, Institut IMAG, 51 rue des Mathématiques, BP 53, 38041 Grenoble Cedex 9, France
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Vassiliou MP, Amygdalou A, Psarakis CJ, Dalavanga Y, Vassiliou PM, Mandragos KE, Constantopoulos SH, Behrakis PK. Volume and flow dependence of respiratory mechanics in mechanically ventilated COPD patients. Respir Physiol Neurobiol 2003; 135:87-96. [PMID: 12706068 DOI: 10.1016/s1569-9048(03)00064-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Volume and flow dependencies of respiratory mechanics are examined in 10 COPD patients under mechanical ventilation (MV) at 3 levels of externally applied PEEP (PEEPe). Airways pressure (Paw), flow (V') and volume (V) data are analyzed according to (1) the linear and (2) a non-linear model, accounting for volume dependence of elastance and for flow and volume dependence of resistance. The models' fitness to data is assessed by the regression errors. Non-linear modelling fits significantly better to data, while the difference of fitness decreases with PEEPe. Linear mechanics are not significantly different between the 3 levels of PEEPe. A positive volume dependence of elastance observed at 0, decreases at 5 and increases again at 10 hPa of PEEPe. A seriously negative volume dependence of resistance at 0 turned to positive with PEEPe. These dependencies of respiratory mechanics during COPD under MV, show that the present non-linear respiratory mechanical monitoring may help for better and less risky adjustment of PEEPe.
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Affiliation(s)
- Miltos P Vassiliou
- The Pneumonology Department, Medical School, University of Ioannina, Ioannina, Greece.
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Edibam C, Rutten AJ, Collins DV, Bersten AD. Effect of inspiratory flow pattern and inspiratory to expiratory ratio on nonlinear elastic behavior in patients with acute lung injury. Am J Respir Crit Care Med 2003; 167:702-7. [PMID: 12598212 DOI: 10.1164/rccm.2012110] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Ventilatory modes employing different inspiratory flow patterns and inspiratory to expiratory ratios may alter lung strain in acute lung injury patients. To determine whether variations in lung strain existed between pressure-controlled, volume-controlled, and pressure-controlled inverse ratio modes of ventilation, we randomly applied each for 30 minutes in 18 acute lung injury patients, keeping tidal volume, respiratory rate, fractional inspired oxygen, and total positive end-expiratory pressure constant. After each mode, a multiple linear regression analysis of dynamic airway pressure and airflow was performed with a volume-dependent single compartment model of the equation of motion, and an index of nonlinear elastic behavior was calculated. In five additional patients, concurrent dynamic computerized axial tomography scanning at juxtadiaphragmatic and subcarinal levels was added. Although static mechanics, oxygenation, and hemodynamics were no different between pressure-controlled, volume-controlled, and pressure-controlled inverse ratio ventilation, we found significant differences in nonlinear behavior. This was least with pressure-controlled followed by volume-controlled ventilation, and pressure-controlled inverse ratio ventilation had the greatest nonlinear elastic behavior. Dynamic computerized axial tomography analysis revealed more overinflated units in the left subcarinal slice with pressure-controlled inverse ratio ventilation. Ventilator flow pattern and inspiratory to expiratory ratio independently influence lung strain in acute lung injury; however, further studies are needed to determine the biologic significance.
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Affiliation(s)
- Cyrus Edibam
- Department of Critical Care Medicine, Flinders Medical Centre, Bedford Park, South Australia
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Wagers S, Lundblad L, Moriya HT, Bates JHT, Irvin CG. Nonlinearity of respiratory mechanics during bronchoconstriction in mice with airway inflammation. J Appl Physiol (1985) 2002; 92:1802-7. [PMID: 11960927 DOI: 10.1152/japplphysiol.00883.2001] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Respiratory system resistance (R) and elastance (E) are commonly estimated by fitting the linear equation of motion P = EV + RV + P0 (Eq. 1) to measurements of respiratory pressure (P), lung volume (V), and flow (V). However, the respiratory system is unlikely to behave linearly under many circumstances. We determined the importance of respiratory system nonlinearities in two groups of mechanically ventilated Balb/c mice [controls and mice with allergically inflamed airways (ova/ova)], by assessing the impact of the addition of nonlinear terms (E2V2 and R2V(V)) on the goodness of model fit seen with Eq. 1. Significant improvement in fit (51.85 +/- 4.19%) was only seen in the ova/ova mice during bronchoconstriction when the E2V2 alone was added. An improvement was also observed with addition of the E2V2 term in mice with both low and high lung volumes ventilated at baseline, suggesting a volume-dependent nonlinearity of E. We speculate that airway closure in the constricted ova/ova mice accentuated the volume-dependent nonlinearity by decreasing lung volume and overdistending the remaining lung.
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Affiliation(s)
- Scott Wagers
- Vermont Lung Center, Department of Medicine, University of Vermont, Burlington 05405, USA.
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Younes M, Webster K, Kun J, Roberts D, Masiowski B. A method for measuring passive elastance during proportional assist ventilation. Am J Respir Crit Care Med 2001; 164:50-60. [PMID: 11435238 DOI: 10.1164/ajrccm.164.1.2010068] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
There are currently no reliable, noninvasive ways to monitor respiratory elastance (E) during assisted ventilation. We describe a method that is suited for proportional assist ventilation (PAV). In this mode, the end of the ventilator's inflation phase occurs during the declining phase of inspiratory effort (Pmus). If the opening of the exhalation valve is delayed, airway pressure (Paw) should initially rise as Pmus continues its decline. When Pmus declines to zero, a Paw plateau should appear. Paw at this point should reflect passive recoil at the prevailing volume. A cohort of 74 ventilator-dependent patients, ventilated in the PAV mode, were studied. Brief end-inspiratory occlusions were applied at random intervals. The magnitude of early change in Paw during the occlusion was inversely related to level of assist (r = 0.7, p < 0.00001). At high assist (> 75%), Paw was nearly flat or declined slightly, indicating minimal residual Pmus at the onset of occlusion. At lower assist levels, Paw increased exponentially in most patients with an average time constant of 0.21 +/- 0.06 s. Extraneous events that may corrupt the measurement (e.g., behavioral responses) were extremely rare (< 0.5%) in the first 0.25 s. From these findings, we concluded that Paw measured 0.25 s from occlusion onset (P0.25) includes little inspiratory Pmus and is free of extraneous events. E, estimated from P0.25 during PAV (EPAV), agreed well (r = 0.92) with passive E measured during controlled ventilation (ECMV); the average difference (EPAV - ECMV) was (+/- SD) -0.3 +/- 4.9 cm H2O x L(-1), corresponding to 0.9 +/- 16.4% of average E. We conclude that Paw measured at 0.25 s from the onset of end-inspiratory occlusion in the PAV mode provides a reliable estimate of passive elastic recoil.
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Affiliation(s)
- M Younes
- Sections of Respiratory and Critical Care Medicine, Department of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
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Franz AR, Mack C, Reichart J, Pohlandt F, Hummler HD. Preserved spontaneous breathing improves cardiac output during partial liquid ventilation. Am J Respir Crit Care Med 2001; 164:36-42. [PMID: 11435236 DOI: 10.1164/ajrccm.164.1.2006164] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The aim of this study was to examine whether preserved spontaneous breathing (SB) supported by proportional-assist ventilation (PAV) would improve cardiac output (CO) during partial liquid ventilation (PLV) in rabbits with and without lung disease if compared with time-cycled, volume-controlled ventilation (CV) combined with muscle paralysis (MP). PLV was initiated in 17 healthy rabbits and 17 surfactant-depleted rabbits using 12 to 15 ml/kg of perfluorodecaline. Both ventilatory modes, SB+PAV and CV+MP, were applied in random sequence using a crossover design. CO was measured by thermodilution. CO was significantly higher during SB+PAV than during CV+MP: 136 +/- 21 ml/kg x min (mean +/- SD) versus 120 +/- 30 ml/kg x min (p = 0.004) in healthy rabbits, and 147 +/- 19 ml/kg x min versus 111 +/- 13 ml/kg x min (p < 0.0001) in surfactant-depleted rabbits, resulting in an improved oxygen delivery. This difference was mainly caused by a larger stroke volume during SB+PAV, whereas there was little change in heart rate. In surfactant-depleted rabbits, SB+PAV resulted in improved arterial blood pressure and arterial and mixed venous pH and in a higher PaO2 at the same level of PEEP and mean airway pressure. We conclude that during PLV, CO is higher during SB+PAV than during CV+MP, resulting in an improved oxygen delivery. In surfactant-depleted rabbits, improved CO, oxygen delivery, and arterial blood pressure resulted in higher pH, possibly reflecting improved tissue perfusion and oxygenation.
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Affiliation(s)
- A R Franz
- Department of Pediatrics, Division of Neonatology and Pediatric Critical Care, University of Ulm, Ulm, Germany.
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Muramatsu K, Yukitake K, Nakamura M, Matsumoto I, Motohiro Y. Monitoring of nonlinear respiratory elastance using a multiple linear regression analysis. Eur Respir J 2001; 17:1158-66. [PMID: 11491159 DOI: 10.1183/09031936.01.00017801] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The elastic pressure/volume (P/V) curve obtained by the multiple linear regression (MLR) technique using a new model, was compared with the quasi-static P/V points obtained by the rapid airway occlusion technique. Seven infants were studied during mechanical ventilation using a pressure controlled mode. The resistive pressure was subtracted from airway opening pressure, thus determining the elastance related pressure, which was then plotted against the volume to make an MLR-elastance curve. Quasi-static P/V curves of the rapid occlusion technique were constructed by plotting the different inspiratory and expiratory volumes against the corresponding values of the quasi-static airway pressure. The calculated MLR-elastance curves closely fit the experimental quasi-static P/V points obtained by the occlusion technique. There were, however, some discrepancies due to the viscoelastic behaviour of the respiratory system. Although slightly altered by these discrepancies, the multiple linear regression-elastance curves did fit the observed quasi-static pressure/volume characteristics for use in clinical practice. The multiple linear regression technique may prove to be clinically useful by continuous monitoring of respiratory system mechanics during mechanical ventilation.
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Affiliation(s)
- K Muramatsu
- Dept of Pediatrics, Fukuoka Tokushukai Medical Center, Kasuga City, Japan
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Kessler V, Guttmann J, Newth CJ. Dynamic respiratory system mechanics in infants during pressure and volume controlled ventilation. Eur Respir J 2001; 17:115-21. [PMID: 11307740 DOI: 10.1183/09031936.01.17101150] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Dynamic respiratory system mechanics can be determined using multiple linear regression (MLR) analysis. There is no need for a particular ventilator setting or for a special ventilatory manoeuvre. The purpose of this study was to investigate whether or not different ventilator modes and the flow-dependent resistance of the endotracheal tube (ETT) influence the determination of resistance and compliance by MLR. Ten paediatric patients who were on controlled mechanical ventilation for various disorders were investigated. The ventilator modes were changed between pressure control (PC) and volume control (VC). Flow and airway pressure were measured and tracheal pressure was continuously calculated. Each mode was applied for 3 min, and 10 consecutive breaths at the end of each period were analysed. Respiratory mechanics were determined by MLR based on either airway pressure, thus including the resistance of the ETT, or tracheal pressure. Resistance was found to be slightly higher in PC than in VC. There was no effect on determination of compliance between the different modes. Elimination of the flow-dependent resistance of the ETT preserved the differences between the modes. The authors conclude that using multiple linear regression compliance is not affected by the actual ventilator mode, whereas resistance is.
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Affiliation(s)
- V Kessler
- Dept of Anesthesiology and Critical Care Medicine, University of Freiburg, Germany
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Abstract
Ventilating patients with acute respiratory failure according to standardized recommendations can lead to varying volume-pressure (V-P) relationships and overdistension. Young children may be more susceptible than adults to overdistension, and individual evaluation of the effects of ventilator settings is therefore required. Three studies have applied indices for the detection of overdistension to dynamic V-P curves in ventilated children. Two of those studies compared these indices to those obtained using a reference technique ([quasi]-static V-P curves), and suggested that the c coefficient of a second order polynomial equation (SOPE) and the ratio of the volume-dependent elastance to total dynamic elastance (%E2) were suitable indices for estimating overdistension.
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Affiliation(s)
- V Nève
- Service de Réanimation Pédiatrique, Centre Hospitalier et Universitaire de Lille, Lille, France.
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Mols G, Hermle G, Schubert J, Miekisch W, Benzing A, Lichtwarck-Aschoff M, Geiger K, Walmrath D, Guttmann J. Volume-dependent compliance and ventilation-perfusion mismatch in surfactant-depleted isolated rabbit lungs. Crit Care Med 2001; 29:144-51. [PMID: 11176175 DOI: 10.1097/00003246-200101000-00029] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Volume-dependent alterations of lung compliance are usually studied over a very large volume range. However, the course of compliance within the comparably small tidal volume (intratidal compliance-volume curve) may also provide relevant information about the impact of mechanical ventilation on pulmonary gas exchange. Consequently, we determined the association of the distribution of ventilation and perfusion with the intratidal compliance-volume curve after modification of positive end-expiratory pressure (PEEP). DESIGN Repeated measurements in randomized order. SETTING An animal laboratory. SUBJECTS Isolated perfused rabbit lungs (n = 14). INTERVENTIONS Surfactant was removed by bronchoalveolar lavage. The lungs were ventilated thereafter with a constant tidal volume (10 mL/kg body weight). Five levels of PEEP (0-4 cm H2O) were applied in random order for 20 mins each. MEASUREMENTS AND MAIN RESULTS The intratidal compliance-volume curve was determined with the slice method for each PEEP level. Concurrently, pulmonary gas exchange was assessed by the multiple inert gas elimination technique. At a PEEP of 0-1 cm H2O, the intratidal compliance-volume curve was formed a bow with downward concavity. At a PEEP of 2 cm H2O, concavity was minimal or compliance was almost constant, whereas higher PEEP levels (3-4 cm H2O) resulted in a decrease of compliance within tidal inflation. Pulmonary gas exchange did not differ between PEEP levels of of 0, 1, and 2 cm H2O. Pulmonary shunt was lowest and perfusion of alveoli with a normal ventilation-perfusion was highest at a PEEP of 3-4 cm H2O. Deadspace ventilation did not change significantly but tended to increase with PEEP. CONCLUSIONS An increase of compliance at the very beginning of tidal inflation was associated with impaired pulmonary gas exchange, indicating insufficient alveolar recruitment by the PEEP level. Consequently, the lowest PEEP level preventing alveolar atelectasis could be detected by analyzing the course of compliance within tidal volume without the need for total lung inflation.
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Affiliation(s)
- G Mols
- Department of Anesthesiology and Critical Care Medicine, University of Freiburg, Germany
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Kessler V, Newth CJ, Guttmann J. Analysis of nonlinear volume-dependent respiratory system mechanics in pediatric patients. Pediatr Crit Care Med 2000; 1:111-8. [PMID: 12813260 DOI: 10.1097/00130478-200010000-00004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Analysis of dynamic respiratory system mechanics is generally based on a resistance-compliance model in which nonlinearities of the respiratory mechanics indices are not considered. The recently developed SLICE method analyzing consecutive volume slices of the tidal volume was used for determination of non-linear volume-dependent respiratory system mechanics. Volume-dependent compliance C(Slice) and resistance R(Slice) were compared with C(MLR) and R(MLR) obtained by standard multiple linear regression analysis (MLR). DESIGN Prospective observational study. SETTING Pediatric intensive care unit in a university hospital. PATIENTS Fifteen pediatric patients, aged 24 days to 9.6 yrs, weighing 3-67.5 kg. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS With respect to their pulmonary status, the patients were grouped into three clinical groups: patients with no lung diseases, patients with restrictive lung diseases, and patients with obstructive lung diseases. All patients were mechanically ventilated via a cuffed endotracheal tube in the pressure-controlled mode. Flow and airway pressure were measured at the proximal end of the tube and tracheal pressure was continuously calculated. Respiratory mechanics were determined either with the SLICE method or, as reference, by using standard MLR. In most patients, the pressure-volume relationship was nonlinear, particularly in patients with restrictive and obstructive lung diseases. In the presence of considerable nonlinearity, the volume-dependent respiratory mechanics indices obtained by the SLICE method showed better agreement between recalculated and original pressure-volume loops compared with the MLR results. Furthermore, signs of overdistension of the patient's lung became obvious when using the SLICE method, whereas they were undetected by MLR. CONCLUSIONS The SLICE method is well suited for the analysis of nonlinear volume-dependent respiratory system mechanics in pediatric patients. The SLICE method may be used as a first step toward an adaptation of ventilator settings with respect to the actual mechanical status of the patient's respiratory system, and, to prevent pulmonary overdistension.
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Affiliation(s)
- V Kessler
- Section of Experimental Anesthesiology, Department of Anesthesiology and Critical Care Medicine, University of Freiburg, Germany
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Schulze-Neick I, Penny DJ, Derrick GP, Dhillon R, Rigby ML, Kelleher A, Bush A, Redington AN. Pulmonary vascular-bronchial interactions: acute reduction in pulmonary blood flow alters lung mechanics. Heart 2000; 84:284-9. [PMID: 10956291 PMCID: PMC1760956 DOI: 10.1136/heart.84.3.284] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Postoperative pulmonary hypertension in children after congenital heart surgery is a risk factor for death and is associated with severe acute changes in both pulmonary vascular resistance and lung mechanics. OBJECTIVE To examine the impact of changes in pulmonary blood flow on lung mechanics in preoperative children with congenital heart disease, in order to assess the cause-effect relation of pulmonary vascular-bronchial interactions. DESIGN Prospective, cross sectional study. SETTING Cardiac catheterisation laboratory, general anaesthesia with mechanical ventilation. INTERVENTIONS Variation of pulmonary blood flow (Qp) by either balloon occlusion of an atrial septal defect before interventional closure, or by complete occlusion of the pulmonary artery during balloon pulmonary valvuloplasty for pulmonary valve stenosis. MAIN OUTCOME MEASURES Ventilatory tidal volume (Vt), dynamic respiratory system compliance (Cdyn), respiratory system resistance (Rrs). RESULTS 28 occlusions were examined in nine patients with atrial septal defect (median age 9.5 years) and 22 in eight patients with pulmonary stenosis (median age 1.2 years). Normalisation of Qp during balloon occlusion of atrial septal defect caused no significant change in airway pressures and Rrs, but there was a small decrease in Vt (mean (SD): 9.61 (0.85) to 9.52 (0.97) ml/kg; p < 0.05) and Cdyn (0.64 (0.11) to 0.59 (0.10) ml/cm H(2)O*kg; p < 0.01). These changes were more pronounced when there was complete cessation of Qp during balloon valvuloplasty in pulmonary stenosis, with a fall in Vt (9.71 (2.95) to 9.32 (2.84) ml/kg; p < 0.05) and Cdyn (0.72 (0.29) to 0.64 (0.26) ml/cm H(2)O*kg; p < 0.001), and there was also an increase in Rrs (25.1 (1. 7) to 28.8 (1.6) cm H(2)O/litre*s; p < 0.01). All these changes exceeded the variability of the baseline measurements more than threefold. CONCLUSIONS Acute changes in pulmonary blood flow are associated with simultaneous changes in lung mechanics. While these changes are small they may represent a valid model to explain the pathophysiological impact of spontaneous changes in pulmonary blood flow in clinically more critical situations in children with congenital heart disease.
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Affiliation(s)
- I Schulze-Neick
- Cardiothoracic Unit, Great Ormond Street Hospital for Children, Great Ormond Street, London WC1 3JN, UK
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Willet KE, Jobe AH, Ikegami M, Newnham J, Sly PD. Pulmonary interstitial emphysema 24 hours after antenatal betamethasone treatment in preterm sheep. Am J Respir Crit Care Med 2000; 162:1087-94. [PMID: 10988135 DOI: 10.1164/ajrccm.162.3.9906103] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
During a series of studies investigating the maturational response to antenatal glucocorticoids, we observed that 70% of lambs delivered at 128 d gestation (term = 150 d), 24 h after a single injection of 0.5 mg/kg betamethasone or betamethasone + L-thyroxine (15 microgram/kg), developed pulmonary interstitial emphysema (PIE), compared with less than 5% of control animals or animals delivered 48 h or 7 d after hormone treatment. This study examined whether the lungs of animals that developed PIE were functionally or structurally different from those that did not. Lambs were mechanically ventilated for 40 min after cesarean section delivery. Hormone-treated animals with PIE were ventilated at similar peak inspiratory pressure (PIP) to control animals, whereas those without PIE were able to be ventilated at significantly lower PIP. Volume-dependent elastance (E2V), which provides an index of overdistension during mechanical ventilation, was lowest in PIE animals. Alveolar architecture was distorted in almost all ventilated animals, the most severe distortion occurring in PIE animals. There was no evidence of excessive alveolar wall thinning in PIE animals, although parenchymal collagen was 30% lower, and elastin 120% higher than in control animals. PIE was associated with structural differences, but not with overventilation.
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Affiliation(s)
- K E Willet
- Division of Clinical Sciences, TVW Telethon Institute for Child Health Research, Perth, Australia.
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Nève V, de la Roque ED, Leclerc F, Leteurtre S, Dorkenoo A, Sadik A, Cremer R, Logier R. Ventilator-induced overdistension in children: dynamic versus low-flow inflation volume-pressure curves. Am J Respir Crit Care Med 2000; 162:139-47. [PMID: 10903233 DOI: 10.1164/ajrccm.162.1.9906091] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We applied to 20 paralyzed ventilated children (0.15 to 14.3 yr, six with acute respiratory distress syndrome [ARDS]) the low-flow inflation (LFI) technique providing quasi-static volume-pressure (V-P) curves and compared the assessment of overdistension (OD) on dynamic and LFI (reference) inspiratory V-P curves. Dynamic curves were obtained at the airway opening during regular constant flow ventilation (Servo 300). Then LFI curves were obtained. Two analyses were performed: First, the nonlinear coefficient c of a second order polynomial equation (SOPE) fitted to dynamic data obtained during constant flow was compared with the c of SOPE fitted to LFI curve (within tidal volume [VT]). Second, the dynamic C20/C (ratio of compliance of the last 20% of the curve (C20) to total compliance [C]) was compared with the determination of the upper inflection point (UIP) on the LFI curve. OD was defined as a negative value of c, a C20/C < 0.80, an UIP included within the VT range for that child during regular ventilation. Using LFI V-P curves as reference, SOPE offered a better detection of OD than dynamic C20/C or the determination of the UIP by graphical means. Indeed the first analysis showed a substantial agreement (kappa 0.75) between dynamic c and LFI c detection of OD whereas the second analysis showed a poor agreement (kappa 0.22) between C20/ C and LFI detection of the UIP. In conclusion, quasi-static V-P curves can easily be obtained in children with the LFI technique. SOPE offers a good detection of OD on dynamic and LFI V-P curves but the C20/C index seems to be an inadequate measure of OD.
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Affiliation(s)
- V Nève
- Service de Réanimation Pédiatrique, Centre Hospitalier et Universitaire de Lille, Lille, France
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Volta CA, Verri M, Righini ER, Ragazzi R, Pavoni V, Alvisi R, Gritti G. Respiratory mechanics during and after anaesthesia for major vascular surgery. Anaesthesia 1999; 54:1041-7. [PMID: 10540092 DOI: 10.1046/j.1365-2044.1999.01068.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To evaluate the effects of major vascular surgery on respiratory mechanics, 11 patients undergoing general anaesthesia for abdominal aortic surgery were studied. Before aortic cross-clamping, chest wall elastance and resistance both increased (by 126% and 58%, respectively) when surgical retractors were placed. After aortic cross-clamping, lung elastance increased by 29%, accompanied by a decrease in cardiac index (22%) and an increase in pulmonary (17%) and systemic (15%) vascular resistance. After aortic unclamping, lung elastance decreased, although it remained higher than baseline values (by 12%). All cardiovascular variables returned to the values obtained before aortic cross-clamping.
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Affiliation(s)
- C A Volta
- Department of Biomedical Science and Advanced Therapy, Section of Anaesthesia and Intensive Care, S. Anna Hospital, University of Ferrara, Italy
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Abstract
The complete equation of motion for a single compartment model (SCM) includes an inertance term to describe pressure changes in phase with acceleration, as well as terms for resistance and elastance. Inertance has traditionally been excluded from the model when measuring respiratory mechanics at conventional ventilatory frequencies in mature respiratory systems. However, this omission has been questioned recently for measurements of respiratory mechanics in intubated infants where higher ventilation frequencies and smaller tracheal tubes are the norm. We investigated 1) the significance of inertance in an immature respiratory system during mechanical ventilation, and 2) the effect of omitting it from the model on estimates of respiratory mechanics. Six anesthetised, paralysed and mechanically ventilated puppies (2.6-3.9 kg) were studied. A SCM, including an inertance term was fitted to measurements of flow and airway opening (P(AO)) or transpulmonary (P(TP)) pressure using multiple linear regression to estimate respiratory system and lung resistance (R(RS), R(L)), elastance (E(RS), E(L)) and inertance (I(RS), I(L)) respectively, at various ventilation frequencies (0.2-2 Hz). Data obtained at each ventilation frequency were also fitted with a similar model without the inertance term. Inertance contributed significantly to the model at frequencies greater than approximately 0.3-0.5 Hz (20-30 breaths per minute), with I(RS) dominated by the lung. The importance of including the inertance term in the model increased as ventilation frequency increased. Exclusion of inertance from the model led to underestimation of E(RS) and E(L), but no errors in estimates of R(RS) or R(L). The errors increased with ventilation frequency to approximately 10-20% for E(RS) and approximately 10-40% for E(L) at 2 Hz. While inertance contributed significantly to the SCM at ventilation frequencies typically required to maintain normal gas exchange in puppies, the errors from excluding this term were small: <3% for E(RS) and <9% for E(L).
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Affiliation(s)
- C J Lanteri
- Institute for Child Health Research, Perth, Western Australia
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Bersten AD, Davidson K, Nicholas TE, Doyle IR. Respiratory mechanics and surfactant in the acute respiratory distress syndrome. Clin Exp Pharmacol Physiol 1998; 25:955-63. [PMID: 9807672 DOI: 10.1111/j.1440-1681.1998.tb02352.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Although abnormalities in pulmonary surfactant were initially implicated in the pathogenesis of the acute respiratory distress syndrome (ARDS) 30 years ago, most subsequent research has focused on mediators of the parenchymal acute lung injury (ALI) and the associated increase in alveolocapillary permeability. 2. Surfactant is essential for normal breathing and the severity of ALI correlates with surfactant dysfunction and abnormalities in surfactant composition; however, no relationship has been shown with respiratory system compliance. In neonates and most animal models, respiratory system compliance will directly reflect the elastic properties of the lung. However, the greater vertical height of the chest wall in adults, in combination with the increase in lung density due to ALI, results in dependent collapse of alveoli. Because simple, global measurement of compliance is strongly influenced by the volume of aerated lung, alternative measures of respiratory mechanics may reflect surfactant dysfunction. 3. Using a dynamic, volume-dependent model of respiratory mechanics to indirectly reflect this heterogeneous inflation, we have found direct relationships with surfactant composition in patients with ARDS. A failure of surfactant to increase surface tension in large alveoli may also explain why lung overdistension occurs at relatively low pressures. Furthermore, surfactant dysfunction will exaggerate heterogeneous lung inflation, augmenting regional overinflation, and is essential for ALI secondary to repetitive opening and closing of alveoli during tidal ventilation. 4. Ventilation-induced ALI has also been shown to result in massive increases in pro-inflammatory cytokines within the lung. Because ALI itself fails to compartmentalize cytokines, with spillover into the systemic circulation resulting in distant organ dysfunction, surfactant dysfunction may have widespread implications.
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Affiliation(s)
- A D Bersten
- Department of Critical Care Medicine, Flinders University, Australia.
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50
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Nikischin W, Gerhardt T, Everett R, Bancalari E. A new method to analyze lung compliance when pressure-volume relationship is nonlinear. Am J Respir Crit Care Med 1998; 158:1052-60. [PMID: 9769260 DOI: 10.1164/ajrccm.158.4.9801011] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Changes in dynamic lung compliance during inspiration and expiration cannot be modeled accurately with conventional algorithms. We developed a simple method to analyze pressure-volume (P/V) relationships under condition of nonlinearity (APVNL) and tested it in a lung model with known resistance and nonlinear P/V relationship. In addition, pulmonary mechanics in 22 infants, 11 of them with nonlinear P/V relationships, were analyzed with the new method. The findings were compared with those obtained by a recently introduced algorithm, multiple linear regression analysis (MLR) of the equation of motion. The APVNL method described the changing compliance (C) of the lung model accurately, whereas the MLR method underestimated C especially in the first half of the breath. In infants the MLR method gave highly variable, often nonphysiological C values in the beginning of a breath. In contrast, the coefficient of variability of measurements obtained by the APVNL method was significantly smaller (p < 0.02), and the indices of model-fit showed better agreement between calculated and observed pressure than for the MLR method (p < 0.02). We conclude that the APVNL method accurately describes nonlinear P/V relationships present during spontaneous breathing or mechanical ventilation. The method may be helpful in identifying and preventing pulmonary overdistention.
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Affiliation(s)
- W Nikischin
- Division of Neonatology, Department of Pediatrics, University of Miami School of Medicine, Miami, Florida, USA
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