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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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Soares JHN, Raff GW, Fineman JR, Datar SA. Respiratory mechanics and gas exchange in an ovine model of congenital heart disease with increased pulmonary blood flow and pressure. Front Physiol 2023; 14:1188824. [PMID: 37362431 PMCID: PMC10288580 DOI: 10.3389/fphys.2023.1188824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 05/30/2023] [Indexed: 06/28/2023] Open
Abstract
In a model of congenital heart disease (CHD), we evaluated if chronically increased pulmonary blood flow and pressure were associated with altered respiratory mechanics and gas exchange. Respiratory mechanics and gas exchange were evaluated in 6 shunt, 7 SHAM, and 7 control age-matched lambs. Lambs were anesthetized and mechanically ventilated for 15 min with tidal volume of 10 mL/kg, positive end-expiratory pressure of 5 cmH2O, and inspired oxygen fraction of 0.21. Respiratory system, lung and chest wall compliances (Crs, CL and Ccw, respectively) and resistances (Rrs, RL and Rcw, respectively), and the profile of the elastic pressure-volume curve (%E2) were evaluated. Arterial blood gases and volumetric capnography variables were collected. Comparisons between groups were performed by one-way ANOVA followed by Tukey-Kramer test for normally distributed data and with Kruskal-Wallis test followed by Steel-Dwass test for non-normally distributed data. Average Crs and CL in shunt lambs were 30% and 58% lower than in control, and 56% and 68% lower than in SHAM lambs, respectively. Ccw was 52% and 47% higher and Rcw was 53% and 40% lower in shunt lambs compared to controls and SHAMs, respectively. No difference in %E2 was identified between groups. No difference in respiratory mechanics was observed between control and SHAM lambs. In shunt lambs, Rcw, Crs and CL were decreased and Ccw was increased when compared to control and SHAM lambs. Pulmonary gas exchange did not seem to be impaired in shunt lambs when compared to controls and SHAMs.
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Affiliation(s)
- Joao Henrique N. Soares
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Gary W. Raff
- Department of Surgery, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Jeffrey R. Fineman
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
- Department of Pediatrics, School of Medicine, University of California, San Francisco, San Francisco, CA, United States
| | - Sanjeev A. Datar
- Department of Pediatrics, School of Medicine, University of California, San Francisco, San Francisco, CA, United States
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Cruz AF, Herrmann J, Carvalho CRR, Kaczka DW. A comparison of endotracheal tube compensation techniques for the measurement of respiratory mechanical impedance at low frequencies. J Clin Monit Comput 2022; 36:1461-1477. [PMID: 34910285 PMCID: PMC9198108 DOI: 10.1007/s10877-021-00788-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 12/01/2021] [Indexed: 11/29/2022]
Abstract
Measurement of respiratory impedance ([Formula: see text]) in intubated patients requires accurate compensation for pressure losses across the endotracheal tube (ETT). In this study, we compared time-domain (TD), frequency-domain (FD) and combined time-/frequency-domain (FT) methods for ETT compensation. We measured total impedance ([Formula: see text]) of a test lung in series with three different ETT sizes, as well as in three intubated porcine subjects. Pressure measurement at the distal end of the ETT was used to determine the true [Formula: see text]. For TD compensation, pressure distal to the ETT was obtained based on its resistive and inertial properties, and the corresponding [Formula: see text] was estimated. For FD compensation, impedance of the isolated ETT was obtained from oscillatory flow and pressure waveforms, and then subtracted from [Formula: see text]. For TF compensation, the nonlinear resistive properties of the ETT were subtracted from the proximal pressure measurement, from which the linear resistive and inertial ETT properties were removed in the frequency-domain to obtain [Formula: see text]. The relative root mean square error between the actual and estimated [Formula: see text] ([Formula: see text]) showed that TD compensation yielded the least accurate estimates of [Formula: see text] for the in vitro experiments, with small deviations observed at higher frequencies. The FD and TF compensations yielded estimates of [Formula: see text] with similar accuracies. For the porcine subjects, no significant differences were observed in [Formula: see text] across compensation methods. FD and TF compensation of the ETT may allow for accurate oscillometric estimates of [Formula: see text] in intubated subjects, while avoiding the difficulties associated with direct tracheal pressure measurement.
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Affiliation(s)
- Andrea F Cruz
- Laboratorio de Pneumologia LIM-09, Disciplina de Pneumologia, Heart Institute (Incor), Hospital das Clinicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, São Paulo, Brazil
- Department of Anesthesia, University of Iowa, Iowa City, IA, USA
| | - Jacob Herrmann
- Department of Anesthesia, University of Iowa, Iowa City, IA, USA
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Carlos R R Carvalho
- Laboratorio de Pneumologia LIM-09, Disciplina de Pneumologia, Heart Institute (Incor), Hospital das Clinicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - David W Kaczka
- Department of Anesthesia, University of Iowa, Iowa City, IA, USA.
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA.
- Department of Radiology, University of Iowa, Iowa City, IA, USA.
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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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Morton SE, Knopp JL, Chase JG, Docherty P, Howe SL, Möller K, Shaw GM, Tawhai M. Optimising mechanical ventilation through model-based methods and automation. ANNUAL REVIEWS IN CONTROL 2019; 48:369-382. [PMID: 36911536 PMCID: PMC9985488 DOI: 10.1016/j.arcontrol.2019.05.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/09/2019] [Accepted: 05/01/2019] [Indexed: 06/11/2023]
Abstract
Mechanical ventilation (MV) is a core life-support therapy for patients suffering from respiratory failure or acute respiratory distress syndrome (ARDS). Respiratory failure is a secondary outcome of a range of injuries and diseases, and results in almost half of all intensive care unit (ICU) patients receiving some form of MV. Funding the increasing demand for ICU is a major issue and MV, in particular, can double the cost per day due to significant patient variability, over-sedation, and the large amount of clinician time required for patient management. Reducing cost in this area requires both a decrease in the average duration of MV by improving care, and a reduction in clinical workload. Both could be achieved by safely automating all or part of MV care via model-based dynamic systems modelling and control methods are ideally suited to address these problems. This paper presents common lung models, and provides a vision for a more automated future and explores predictive capacity of some current models. This vision includes the use of model-based methods to gain real-time insight to patient condition, improve safety through the forward prediction of outcomes to changes in MV, and develop virtual patients for in-silico design and testing of clinical protocols. Finally, the use of dynamic systems models and system identification to guide therapy for improved personalised control of oxygenation and MV therapy in the ICU will be considered. Such methods are a major part of the future of medicine, which includes greater personalisation and predictive capacity to both optimise care and reduce costs. This review thus presents the state of the art in how dynamic systems and control methods can be applied to transform this core area of ICU medicine.
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Affiliation(s)
- Sophie E Morton
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - Jennifer L Knopp
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - J Geoffrey Chase
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - Paul Docherty
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - Sarah L Howe
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - Knut Möller
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Geoffrey M Shaw
- Department of Intensive Care, Christchurch Hospital, Christchurch, New Zealand
| | - Merryn Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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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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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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Rodrigues GG, Freitas US, Bounoiare D, Aguirre LA, Letellier C. Leakage estimation using Kalman filtering in noninvasive mechanical ventilation. IEEE Trans Biomed Eng 2012; 60:1234-40. [PMID: 23221796 DOI: 10.1109/tbme.2012.2230630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Noninvasive mechanical ventilation is today often used to assist patient with chronic respiratory failure. One of the main reasons evoked to explain asynchrony events, discomfort, unwillingness to be treated, etc., is the occurrence of nonintentional leaks in the ventilation circuit, which are difficult to account for because they are not measured. This paper describes a solution to the problem of variable leakage estimation based on a Kalman filter driven by airflow and the pressure signals, both of which are available in the ventilation circuit. The filter was validated by showing that based on the attained leakage estimates, practically all the untriggered cycles can be explained.
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Affiliation(s)
- G G Rodrigues
- Centro Federal de Educação Tecnológica de Minas Gerais, Belo Horizonte 30510-000, MG, Brazil
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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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Zhao Z, Guttmann J, Möller K. Adaptive SLICE method: an enhanced method to determine nonlinear dynamic respiratory system mechanics. Physiol Meas 2011; 33:51-64. [PMID: 22155927 DOI: 10.1088/0967-3334/33/1/51] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The objective of this paper is to introduce and evaluate the adaptive SLICE method (ASM) for continuous determination of intratidal nonlinear dynamic compliance and resistance. The tidal volume is subdivided into a series of volume intervals called slices. For each slice, one compliance and one resistance are calculated by applying a least-squares-fit method. The volume window (width) covered by each slice is determined based on the confidence interval of the parameter estimation. The method was compared to the original SLICE method and evaluated using simulation and animal data. The ASM was also challenged with separate analysis of dynamic compliance during inspiration. If the signal-to-noise ratio (SNR) in the respiratory data decreased from +∞ to 10 dB, the relative errors of compliance increased from 0.1% to 22% for the ASM and from 0.2% to 227% for the SLICE method. Fewer differences were found in resistance. When the SNR was larger than 40 dB, the ASM delivered over 40 parameter estimates (42.2 ± 1.3). When analyzing the compliance during inspiration separately, the estimates calculated with the ASM were more stable. The adaptive determination of slice bounds results in consistent and reliable parameter values. Online analysis of nonlinear respiratory mechanics will profit from such an adaptive selection of interval size.
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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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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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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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Lozano-Zahonero S, Gottlieb D, Haberthür C, Guttmann J, Möller K. Automated mechanical ventilation: adapting decision making to different disease states. Med Biol Eng Comput 2010; 49:349-58. [PMID: 21069471 DOI: 10.1007/s11517-010-0712-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 10/27/2010] [Indexed: 10/18/2022]
Abstract
The purpose of the present study is to introduce a novel methodology for adapting and upgrading decision-making strategies concerning mechanical ventilation with respect to different disease states into our fuzzy-based expert system, AUTOPILOT-BT. The special features are: (1) Extraction of clinical knowledge in analogy to the daily routine. (2) An automated process to obtain the required information and to create fuzzy sets. (3) The controller employs the derived fuzzy rules to achieve the desired ventilation status. For demonstration this study focuses exclusively on the control of arterial CO(2) partial pressure (p(a)CO(2)). Clinical knowledge from 61 anesthesiologists was acquired using a questionnaire from which different disease-specific fuzzy sets were generated to control p(a)CO(2). For both, patients with healthy lung and with acute respiratory distress syndrome (ARDS) the fuzzy sets show different shapes. The fuzzy set "normal", i.e., "target p(a)CO(2) area", ranges from 35 to 39 mmHg for healthy lungs and from 39 to 43 mmHg for ARDS lungs. With the new fuzzy sets our AUTOPILOT-BT reaches the target p(a)CO(2) within maximal three consecutive changes of ventilator settings. Thus, clinical knowledge can be extended, updated, and the resulting mechanical ventilation therapies can be individually adapted, analyzed, and evaluated.
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Affiliation(s)
- S Lozano-Zahonero
- Department of Biomedical Engineering, Furtwangen University, Villingen-Schwenningen Campus, Jakob Kienzle Straße 17, Villingen-Schwenningen, 78054, Germany.
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The augmented RIC model of the human respiratory system. Med Biol Eng Comput 2009; 47:395-404. [PMID: 19184154 DOI: 10.1007/s11517-009-0443-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Accepted: 01/12/2009] [Indexed: 10/21/2022]
Abstract
This paper describes the augmented RIC model of respiratory impedance and analyzes its parameter values estimated--by a modified Newton method with least squares criterion--from impulse oscillometry data. The data were from asthmatic children, tested pre- and post-bronchodilator, and from healthy adults and a second group of adults with COPD. Our analyses show that the augmented RIC model was 13.7-66.6% more accurate than the extended RIC model at fitting these data, while its parameter estimates were within previously reported ranges, unlike the Mead 1969, DuBois and Mead models, which typically yielded compliance estimates exceeding 200 l/kPa. Additionally, the augmented RIC model's C(p) parameter, representing peripheral airway compliance, is a statistically significant discriminator between unconstricted and constricted conditions (with p < 0.001) occurring in asthma and COPD. This corresponds well with current medical understanding, so the augmented RIC model is potentially useful for detection and treatment of airflow obstruction.
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