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Cronin JN, Crockett DC, Perchiazzi G, Farmery AD, Camporota L, Formenti F. Intra-tidal PaO 2 oscillations associated with mechanical ventilation: a pilot study to identify discrete morphologies in a porcine model. Intensive Care Med Exp 2023; 11:60. [PMID: 37672140 PMCID: PMC10482813 DOI: 10.1186/s40635-023-00544-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 08/28/2023] [Indexed: 09/07/2023] Open
Abstract
BACKGROUND Within-breath oscillations in arterial oxygen tension (PaO2) can be detected using fast responding intra-arterial oxygen sensors in animal models. These PaO2 signals, which rise in inspiration and fall in expiration, may represent cyclical recruitment/derecruitment and, therefore, a potential clinical monitor to allow titration of ventilator settings in lung injury. However, in hypovolaemia models, these oscillations have the potential to become inverted, such that they decline, rather than rise, in inspiration. This inversion suggests multiple aetiologies may underlie these oscillations. A correct interpretation of the various PaO2 oscillation morphologies is essential to translate this signal into a monitoring tool for clinical practice. We present a pilot study to demonstrate the feasibility of a new analysis method to identify these morphologies. METHODS Seven domestic pigs (average weight 31.1 kg) were studied under general anaesthesia with muscle relaxation and mechanical ventilation. Three underwent saline-lavage lung injury and four were uninjured. Variations in PEEP, tidal volume and presence/absence of lung injury were used to induce different morphologies of PaO2 oscillation. Functional principal component analysis and k-means clustering were employed to separate PaO2 oscillations into distinct morphologies, and the cardiorespiratory physiology associated with these PaO2 morphologies was compared. RESULTS PaO2 oscillations from 73 ventilatory conditions were included. Five functional principal components were sufficient to explain ≥ 95% of the variance of the recorded PaO2 signals. From these, five unique morphologies of PaO2 oscillation were identified, ranging from those which increased in inspiration and decreased in expiration, through to those which decreased in inspiration and increased in expiration. This progression was associated with the estimates of the first functional principal component (P < 0.001, R2 = 0.88). Intermediate morphologies demonstrated waveforms with two peaks and troughs per breath. The progression towards inverted oscillations was associated with increased pulse pressure variation (P = 0.03). CONCLUSIONS Functional principal component analysis and k-means clustering are appropriate to identify unique morphologies of PaO2 waveform associated with distinct cardiorespiratory physiology. We demonstrated novel intermediate morphologies of PaO2 waveform, which may represent a development of zone 2 physiologies within the lung. Future studies of PaO2 oscillations and modelling should aim to understand the aetiologies of these morphologies.
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Affiliation(s)
- John N Cronin
- Department of Anaesthesia and Perioperative Medicine, St. Thomas' Hospital, Guy's and St. Thomas' NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK.
- Faculty of Life Sciences and Medicine, King's College London, London, UK.
| | - Douglas C Crockett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Gaetano Perchiazzi
- Hedenstierna Laboratory, Department of Surgical Sciences, University of Uppsala, Uppsala, Sweden
| | - Andrew D Farmery
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Luigi Camporota
- Faculty of Life Sciences and Medicine, King's College London, London, UK
- Department of Intensive Care, Guy's and St. Thomas' NHS Foundation Trust, London, UK
| | - Federico Formenti
- Faculty of Life Sciences and Medicine, King's College London, London, UK
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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2
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Hummer EV, Soares JHN, Crockett DC, Aguiar AJA, Tran MC, Cronin JN, Brosnan RJ, Braun C, Formenti F. Continuous measurement of arterial oxygenation in mechanically ventilated horses. Equine Vet J 2021; 54:1144-1152. [PMID: 34797580 DOI: 10.1111/evj.13542] [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: 08/16/2021] [Revised: 11/01/2021] [Accepted: 11/11/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND The possibility of accurately and continuously measuring arterial oxygen partial pressure (PaO2 ) in horses may facilitate the management of hypoxaemia during general anaesthesia. OBJECTIVES The aim of this study was to evaluate the ability of a novel fibreoptic sensor to measure PaO2 (PaO2Sensor ) continuously and in real time in horses undergoing ventilatory manoeuvres during general anaesthesia. STUDY DESIGN In vivo experimental study. METHODS Six adult healthy horses were anaesthetised and mechanically ventilated in dorsal recumbency. A fibreoptic sensor was placed in one of the facial arteries through a catheter to continuously measure and record PaO2Sensor . After an alveolar recruitment manoeuvre, a decremental positive end-expiratory pressure (PEEP) titration using 20-minute steps of 5 cm H2 O from 20 to 0 cm H2 O was performed. An arterial blood sample was collected at 15 minutes of ventilation at each PEEP level for PaO2 measurement using an automated blood gas machine (PaO2Ref ). The agreement between PaO2Sensor and PaO2Ref was assessed by Pearson's correlation, Bland-Altman plot and four-quadrant plot analysis. In the last minute of ventilation at each PEEP level, a slow tidal inflation/deflation manoeuvre was performed. RESULTS The mean relative bias between PaO2Sensor and PaO2Ref was 4% with limits of agreement between -17% and 29%. The correlation coefficient between PaO2Sensor and PaO2Ref was 0.98 (P < .001). The PaO2Sensor and PaO2Ref concordance rate for changes was 95%. Measurements of PaO2Sensor during the slow inflation/deflation manoeuvre at PEEP 15 and 10 cm H2 O were not possible because of significant noise on the PaO2 signal generated by a small blood clot. MAIN LIMITATIONS Small sample size. CONCLUSION The tested fibreoptic probe was able to accurately and continuously measure PaO2Sensor in anaesthetised horses undergoing ventilatory manoeuvres. A heparinised system in the catheter used by the fibreoptic sensor should be used to avoid blood clots and artefacts in the PaO2 measurements.
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Affiliation(s)
- Emma V Hummer
- William Pritchard Veterinary Medical Teaching Hospital, University of California Davis, Davis, California, USA
| | - Joao H N Soares
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, California, USA
| | | | - Antonio J A Aguiar
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, California, USA.,Departamento de Cirurgia e Anestesiologia Veterinária, Faculdade de Medicina Veterinária e Zootecnia, UNESP - Univ. Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Minh C Tran
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK.,Department of Engineering Science, University of Oxford, Oxford, UK
| | - John N Cronin
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK.,Department of Anaesthetics, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Robert J Brosnan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, California, USA
| | - Christina Braun
- Anaesthesiology and Perioperative Intensive Care, Vetmeduni Vienna, Vienna, Austria
| | - Federico Formenti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK.,Centre for Human and Applied Physiological Sciences, King's College London, London, UK
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3
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Gallifant J, Cronin JN, Formenti F. Quantification of lobar gas exchange: a proof-of-concept study in pigs. Br J Anaesth 2021; 127:e55-e58. [PMID: 34116804 DOI: 10.1016/j.bja.2021.04.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/13/2021] [Accepted: 04/16/2021] [Indexed: 11/17/2022] Open
Affiliation(s)
- Jack Gallifant
- Centre for Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, King's College London, London, UK
| | - John N Cronin
- Centre for Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, King's College London, London, UK; Department of Anaesthesia, Guy's and St Thomas' NHS Foundation Trust, London, UK.
| | - Federico Formenti
- Centre for Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, King's College London, London, UK; Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK; Department of Biomechanics, University of Nebraska Omaha, Omaha, NE, USA.
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4
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Tran MC, Crockett DC, Cronin JN, Borges JB, Hedenstierna G, Larsson A, Farmery AD, Formenti F. Bedside monitoring of lung volume available for gas exchange. Intensive Care Med Exp 2021; 9:3. [PMID: 33496887 PMCID: PMC7835652 DOI: 10.1186/s40635-020-00364-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/02/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Bedside measurement of lung volume may provide guidance in the personalised setting of respiratory support, especially in patients with the acute respiratory distress syndrome at risk of ventilator-induced lung injury. We propose here a novel operator-independent technique, enabled by a fibre optic oxygen sensor, to quantify the lung volume available for gas exchange. We hypothesised that the continuous measurement of arterial partial pressure of oxygen (PaO2) decline during a breath-holding manoeuvre could be used to estimate lung volume in a single-compartment physiological model of the respiratory system. METHODS Thirteen pigs with a saline lavage lung injury model and six control pigs were studied under general anaesthesia during mechanical ventilation. Lung volumes were measured by simultaneous PaO2 rate of decline (VPaO2) and whole-lung computed tomography scan (VCT) during apnoea at different positive end-expiratory and end-inspiratory pressures. RESULTS A total of 146 volume measurements was completed (range 134 to 1869 mL). A linear correlation between VCT and VPaO2 was found both in control (slope = 0.9, R2 = 0.88) and in saline-lavaged pigs (slope = 0.64, R2 = 0.70). The bias from Bland-Altman analysis for the agreement between the VCT and VPaO2 was - 84 mL (limits of agreement ± 301 mL) in control and + 2 mL (LoA ± 406 mL) in saline-lavaged pigs. The concordance for changes in lung volume, quantified with polar plot analysis, was - 4º (LoA ± 19°) in control and - 9° (LoA ± 33°) in saline-lavaged pigs. CONCLUSION Bedside measurement of PaO2 rate of decline during apnoea is a potential approach for estimation of lung volume changes associated with different levels of airway pressure.
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Affiliation(s)
- Minh C Tran
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK.
- Department of Engineering Science, University of Oxford, Oxford, UK.
| | | | - John N Cronin
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK
- Department of Anaesthetics, Guy's and St. Thomas' NHS Foundation Trust, London, UK
| | - João Batista Borges
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK
| | - Göran Hedenstierna
- Hedenstierna Laboratory, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Anders Larsson
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Andrew D Farmery
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - Federico Formenti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK.
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK.
- Department of Biomechanics, University of Nebraska, Omaha, NE, USA.
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5
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Synthesis and properties of fluorinated cyclometalated Ir(III) complexes. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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6
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Nieman GF, Gatto LA, Andrews P, Satalin J, Camporota L, Daxon B, Blair SJ, Al-Khalisy H, Madden M, Kollisch-Singule M, Aiash H, Habashi NM. Prevention and treatment of acute lung injury with time-controlled adaptive ventilation: physiologically informed modification of airway pressure release ventilation. Ann Intensive Care 2020; 10:3. [PMID: 31907704 PMCID: PMC6944723 DOI: 10.1186/s13613-019-0619-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 12/23/2019] [Indexed: 12/16/2022] Open
Abstract
Mortality in acute respiratory distress syndrome (ARDS) remains unacceptably high at approximately 39%. One of the only treatments is supportive: mechanical ventilation. However, improperly set mechanical ventilation can further increase the risk of death in patients with ARDS. Recent studies suggest that ventilation-induced lung injury (VILI) is caused by exaggerated regional lung strain, particularly in areas of alveolar instability subject to tidal recruitment/derecruitment and stress-multiplication. Thus, it is reasonable to expect that if a ventilation strategy can maintain stable lung inflation and homogeneity, regional dynamic strain would be reduced and VILI attenuated. A time-controlled adaptive ventilation (TCAV) method was developed to minimize dynamic alveolar strain by adjusting the delivered breath according to the mechanical characteristics of the lung. The goal of this review is to describe how the TCAV method impacts pathophysiology and protects lungs with, or at high risk of, acute lung injury. We present work from our group and others that identifies novel mechanisms of VILI in the alveolar microenvironment and demonstrates that the TCAV method can reduce VILI in translational animal ARDS models and mortality in surgical/trauma patients. Our TCAV method utilizes the airway pressure release ventilation (APRV) mode and is based on opening and collapsing time constants, which reflect the viscoelastic properties of the terminal airspaces. Time-controlled adaptive ventilation uses inspiratory and expiratory time to (1) gradually “nudge” alveoli and alveolar ducts open with an extended inspiratory duration and (2) prevent alveolar collapse using a brief (sub-second) expiratory duration that does not allow time for alveolar collapse. The new paradigm in TCAV is configuring each breath guided by the previous one, which achieves real-time titration of ventilator settings and minimizes instability induced tissue damage. This novel methodology changes the current approach to mechanical ventilation, from arbitrary to personalized and adaptive. The outcome of this approach is an open and stable lung with reduced regional strain and greater lung protection.
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Affiliation(s)
- Gary F Nieman
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Louis A Gatto
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Penny Andrews
- Multi-trauma Critical Care, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, 22 South Greene Street, Baltimore, MD, USA
| | - Joshua Satalin
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA.
| | - Luigi Camporota
- Department of Critical Care, Guy's and St, Thomas' NHS Foundation Trust, Westminster Bridge Rd, London, SE1 7EH, UK
| | - Benjamin Daxon
- Dept of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 1st St SW, Rochester, MN, 55905, USA
| | - Sarah J Blair
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Hassan Al-Khalisy
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Maria Madden
- Multi-trauma Critical Care, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, 22 South Greene Street, Baltimore, MD, USA
| | | | - Hani Aiash
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA.,Department of Clinical Perfusion, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Nader M Habashi
- Multi-trauma Critical Care, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, 22 South Greene Street, Baltimore, MD, USA
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7
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Formenti F, Farmery AD. Intravascular oxygen sensors with novel applications for bedside respiratory monitoring. Anaesthesia 2018; 72 Suppl 1:95-104. [PMID: 28044329 PMCID: PMC5396266 DOI: 10.1111/anae.13745] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2016] [Indexed: 11/26/2022]
Abstract
Measurement allows us to quantify various parameters and variables in natural systems. In addition, by measuring the effect by which a perturbation of one part of the system influences the system as a whole, insights into the functional mechanisms of the system can be inferred. Clinical monitoring has a different role to that of scientific measurement. Monitoring describes measurements whose prime purpose is not to give insights into underlying mechanisms, but to provide information to ‘warn’ of imminent events. What is often more important is the description of trends in measured variables. In this article, we give some examples ‐ focussed around oxygen sensors ‐ of how new sensors can make important measurements and might in the future contribute to improved clinical management.
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Affiliation(s)
- F Formenti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK.,Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - A D Farmery
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
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8
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Crockett DC, Cronin JN, Bommakanti N, Chen R, Hahn CEW, Hedenstierna G, Larsson A, Farmery AD, Formenti F. Tidal changes in PaO 2 and their relationship to cyclical lung recruitment/derecruitment in a porcine lung injury model. Br J Anaesth 2018; 122:277-285. [PMID: 30686314 PMCID: PMC6354046 DOI: 10.1016/j.bja.2018.09.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 08/21/2018] [Accepted: 09/10/2018] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Tidal recruitment/derecruitment (R/D) of collapsed regions in lung injury has been presumed to cause respiratory oscillations in the partial pressure of arterial oxygen (PaO2). These phenomena have not yet been studied simultaneously. We examined the relationship between R/D and PaO2 oscillations by contemporaneous measurement of lung-density changes and PaO2. METHODS Five anaesthetised pigs were studied after surfactant depletion via a saline-lavage model of R/D. The animals were ventilated with a mean fraction of inspired O2 (FiO2) of 0.7 and a tidal volume of 10 ml kg-1. Protocolised changes in pressure- and volume-controlled modes, inspiratory:expiratory ratio (I:E), and three types of breath-hold manoeuvres were undertaken. Lung collapse and PaO2 were recorded using dynamic computed tomography (dCT) and a rapid PaO2 sensor. RESULTS During tidal ventilation, the expiratory lung collapse increased when I:E <1 [mean (standard deviation) lung collapse=15.7 (8.7)%; P<0.05], but the amplitude of respiratory PaO2 oscillations [2.2 (0.8) kPa] did not change during the respiratory cycle. The expected relationship between respiratory PaO2 oscillation amplitude and R/D was therefore not clear. Lung collapse increased during breath-hold manoeuvres at end-expiration and end-inspiration (14% vs 0.9-2.1%; P<0.0001). The mean change in PaO2 from beginning to end of breath-hold manoeuvres was significantly different with each type of breath-hold manoeuvre (P<0.0001). CONCLUSIONS This study in a porcine model of collapse-prone lungs did not demonstrate the expected association between PaO2 oscillation amplitude and the degree of recruitment/derecruitment. The results suggest that changes in pulmonary ventilation are not the sole determinant of changes in PaO2 during mechanical ventilation in lung injury.
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Affiliation(s)
- D C Crockett
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK.
| | - J N Cronin
- Centre for Human and Applied Physiological Sciences, King's College, London, UK
| | - N Bommakanti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - R Chen
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - C E W Hahn
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - G Hedenstierna
- Hedenstierna Laboratory, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - A Larsson
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - A D Farmery
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - F Formenti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK; Centre for Human and Applied Physiological Sciences, King's College, London, UK; Department of Biomechanics, University of Nebraska Omaha, Omaha, NE, USA.
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9
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Preemptive Mechanical Ventilation Based on Dynamic Physiology in the Alveolar Microenvironment: Novel Considerations of Time-Dependent Properties of the Respiratory System. J Trauma Acute Care Surg 2018; 85:1081-1091. [PMID: 30124627 DOI: 10.1097/ta.0000000000002050] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The acute respiratory distress syndrome (ARDS) remains a serious clinical problem with the current treatment being supportive in the form of mechanical ventilation. However, mechanical ventilation can be a double-edged sword; if set properly, it can significantly reduce ARDS associated mortality but if set improperly it can have unintended consequences causing a secondary ventilator induced lung injury (VILI). The hallmark of ARDS pathology is a heterogeneous lung injury, which predisposes the lung to a secondary VILI. The current standard of care approach is to wait until ARDS is well established and then apply a low tidal volume (LVt) strategy to avoid over-distending the remaining normal lung. However, even with the use of LVt strategy, the mortality of ARDS remains unacceptably high at ~40%. In this review, we analyze the lung pathophysiology associated with ARDS that renders the lung highly vulnerable to a secondary VILI. The current standard of care LVt strategy is critiqued as well as new strategies used in combination with LVt to protect the lung. Using the current understanding of alveolar mechanics (i.e. the dynamic change in alveolar size and shape with tidal ventilation) we provide a rationale for why the current protective ventilation strategies have not further reduced ARDS mortality. New strategies of protective ventilation based on dynamic physiology in the micro-environment (i.e. alveoli and alveolar ducts) are discussed. Current evidence suggests that alveolar inflation and deflation is viscoelastic in nature, with a fast and slow phase in both alveolar recruitment and collapse. Using this knowledge, a ventilation strategy with a prolonged time at inspiration would recruit alveoli and a brief release time at expiration would prevent alveolar collapse, converting heterogeneous to homogeneous lung inflation significantly reducing ARDS incidence and mortality.
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10
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Davenport JJ, Hickey M, Phillips JP, Kyriacou PA. Dual pO 2/pCO 2 fibre optic sensing film. Analyst 2018; 142:1711-1719. [PMID: 28401218 DOI: 10.1039/c7an00173h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A fibre optic multi-sensor has been developed for biomedical sensing applications using a tip coating solution sensitive to both oxygen and carbon dioxide. An oxygen sensitive phosphorescence quenching complex based on platinum octaethylporphyrin (PtOEP) was combined with a carbon dioxide sensitive phosphorescence compound based on 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS). When excited by blue light (470 nm), the resultant coating had two fluorescent peaks at 515 nm (green) and 645 nm (red) which responded to partial pressure of CO2 and O2 respectively. The sensor was tested in vitro and shown to be able to measure CO2 and O2 simultaneously and in real time, with calibration constants of 0.0384 kPa-1 and 0.309 kPa-1 respectively. The O2 sensitive peak received some overlap from the 515 nm peak (0.38% of peak intensity) as well as some cross-sensitivity (maximum, 5.1 kPa pCO2 gave a measurement equivalent to 0.43 kPa of O2, a ratio of 0.08 : 1). However, these effects can be subtracted from measurements and no significant cross-sensitivity or overlap was seen in CO2 measurements from O2. This novel compound presents great potential for use in medical sensors and we expect it to be important to a wide range of future applications.
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Affiliation(s)
- John J Davenport
- Research Centre for Biomedical Engineering, University of London, Northampton Square, London, EC1V 0HB, UK.
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11
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Formenti F, Bommakanti N, Chen R, Cronin JN, McPeak H, Holopherne-Doran D, Hedenstierna G, Hahn CEW, Larsson A, Farmery AD. Respiratory oscillations in alveolar oxygen tension measured in arterial blood. Sci Rep 2017; 7:7499. [PMID: 28878215 PMCID: PMC5587703 DOI: 10.1038/s41598-017-06975-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 06/20/2017] [Indexed: 01/02/2023] Open
Abstract
Arterial oxygen partial pressure can increase during inspiration and decrease during expiration in the presence of a variable shunt fraction, such as with cyclical atelectasis, but it is generally presumed to remain constant within a respiratory cycle in the healthy lung. We measured arterial oxygen partial pressure continuously with a fast intra-vascular sensor in the carotid artery of anaesthetized, mechanically ventilated pigs, without lung injury. Here we demonstrate that arterial oxygen partial pressure shows respiratory oscillations in the uninjured pig lung, in the absence of cyclical atelectasis (as determined with dynamic computed tomography), with oscillation amplitudes that exceeded 50 mmHg, depending on the conditions of mechanical ventilation. These arterial oxygen partial pressure respiratory oscillations can be modelled from a single alveolar compartment and a constant oxygen uptake, without the requirement for an increased shunt fraction during expiration. Our results are likely to contribute to the interpretation of arterial oxygen respiratory oscillations observed during mechanical ventilation in the acute respiratory distress syndrome.
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Affiliation(s)
- Federico Formenti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom. .,Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom.
| | - Nikhil Bommakanti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | - Rongsheng Chen
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | - John N Cronin
- Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Hanne McPeak
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | | | | | - Clive E W Hahn
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | - Anders Larsson
- Department of Surgical Sciences, University of Uppsala, Uppsala, Sweden
| | - Andrew D Farmery
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
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12
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Cyclic PaO 2 oscillations assessed in the renal microcirculation: correlation with tidal volume in a porcine model of lung lavage. BMC Anesthesiol 2017; 17:92. [PMID: 28693425 PMCID: PMC5504855 DOI: 10.1186/s12871-017-0382-7] [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: 12/30/2016] [Accepted: 06/30/2017] [Indexed: 01/08/2023] Open
Abstract
Background Oscillations of the arterial partial pressure of oxygen induced by varying shunt fractions occur during cyclic alveolar recruitment within the injured lung. Recently, these were proposed as a pathomechanism that may be relevant for remote organ injury following acute respiratory distress syndrome. This study examines the transmission of oxygen oscillations to the renal tissue and their tidal volume dependency. Methods Lung injury was induced by repetitive bronchoalveolar lavage in eight anaesthetized pigs. Cyclic alveolar recruitment was provoked by high tidal volume ventilation. Oscillations of the arterial partial pressure of oxygen were measured in real-time in the macrocirculation by multi-frequency phase fluorimetry and in the renal microcirculation by combined white-light spectrometry and laser-Doppler flowmetry during tidal volume down-titration. Results Significant respiratory-dependent oxygen oscillations were detected in the macrocirculation and transmitted to the renal microcirculation in a substantial extent. The amplitudes of these oscillations significantly correlate to the applied tidal volume and are minimized during down-titration. Conclusions In a porcine model oscillations of the arterial partial pressure of oxygen are induced by cyclic alveolar recruitment and transmitted to the renal microcirculation in a tidal volume-dependent fashion. They might play a role in organ crosstalk and remote organ damage following lung injury.
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Li S, Han Y, Lei H, Zeng Y, Cui Z, Zeng Q, Zhu D, Lian R, Zhang J, Chen Z, Chen J. In vitro biomimetic platforms featuring a perfusion system and 3D spheroid culture promote the construction of tissue-engineered corneal endothelial layers. Sci Rep 2017; 7:777. [PMID: 28396609 PMCID: PMC5429708 DOI: 10.1038/s41598-017-00914-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/16/2017] [Indexed: 11/08/2022] Open
Abstract
Corneal endothelial cells (CECs) are very important for the maintenance of corneal transparency. However, in vitro, CECs display limited proliferation and loss of phenotype via endothelial to mesenchymal transformation (EMT) and cellular senescence. In this study, we demonstrate that continuous supplementary nutrition using a perfusion culture bioreactor and three-dimensional (3D) spheroid culture can be used to improve CEC expansion in culture and to construct a tissue-engineered CEC layer. Compared with static culture, perfusion-derived CECs exhibited an increased proliferative ability as well as formed close cell-cell contact junctions and numerous surface microvilli. We also demonstrated that the CEC spheroid culture significantly down-regulated gene expression of the proliferation marker Ki67 and EMT-related markers Vimentin and α-SMA, whereas the gene expression level of the CEC marker ATP1A1 was significantly up-regulated. Furthermore, use of the perfusion system in conjunction with a spheroid culture on decellularized corneal scaffolds and collagen sheets promoted the generation of CEC monolayers as well as neo-synthesized ECM formation. This study also confirmed that a CEC spheroid culture on a curved collagen sheet with controlled physiological intraocular pressure could generate a CEC monolayer. Thus, our results show that the use of a perfusion system and 3D spheroid culture can promote CEC expansion and the construction of tissue-engineered corneal endothelial layers in vitro.
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Affiliation(s)
- Shanyi Li
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, 510632, P.R. China
| | - Yuting Han
- The Department of Ophthalmology, the First Clinical Medical College, Jinan University, Guangzhou, 510632, P.R. China
| | - Hao Lei
- Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou, 510632, P.R. China
| | - Yingxin Zeng
- Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou, 510632, P.R. China
- Department of Applied Physics, South China Agricultural University, Guangzhou, 510632, P.R. China
| | - Zekai Cui
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, 510632, P.R. China
| | - Qiaolang Zeng
- The Department of Ophthalmology, the First Clinical Medical College, Jinan University, Guangzhou, 510632, P.R. China
| | - Deliang Zhu
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, 510632, P.R. China
| | - Ruiling Lian
- The Department of Ophthalmology, the First Clinical Medical College, Jinan University, Guangzhou, 510632, P.R. China
| | - Jun Zhang
- Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou, 510632, P.R. China
| | - Zhe Chen
- Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou, 510632, P.R. China.
| | - Jiansu Chen
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, 510632, P.R. China.
- Institute of Ophthalmology, Medical College, Jinan University, Jinan University, Guangzhou, 510632, P.R. China.
- The Department of Ophthalmology, the First Clinical Medical College, Jinan University, Guangzhou, 510632, P.R. China.
- Aier Eye Institute, #198 Furong Middle Road, Changsha, 410015, P.R. China.
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14
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Davenport JJ, Hickey M, Phillips JP, Kyriacou PA. Fiber-optic fluorescence-quenching oxygen partial pressure sensor using platinum octaethylporphyrin. APPLIED OPTICS 2016; 55:5603-5609. [PMID: 27463913 DOI: 10.1364/ao.55.005603] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The development and bench testing of a fiber-optic oxygen sensor is described. The sensor is designed for measurement of tissue oxygen levels in the mucosa of the digestive tract. The materials and construction are optimized for insertion through the mouth for measurement in the lower esophagus. An oxygen-sensitive fluorescence-quenching film was applied as a solution of platinum octaethylporphyrin (PtOEP) poly(ethyl methacrylate) (PEMA) and dichloromethane and dip coated onto the distal tip of the fiber. The sensor was tested by comparing relative fluorescence when immersed in liquid water at 37°C, at a range of partial pressures (0-101 kPa). Maximum relative fluorescence at most oxygen concentrations was seen when the PtOEP concentration was 0.1 g.L-1, four layers of coating solution were applied, and a fiber core radius of 600 μm was selected, giving a Stern-Volmer constant of 0.129 kPa-1. The performance of the sensor is suitable for many in vivo applications, particularly mucosal measurements. It has sufficient sensitivity, is sterilizable, and is sufficiently flexible and robust for insertion via the mouth without damage to the probe or risk of harm to the patient.
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15
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Wu J, Stefaniak J, Hafner C, Schramel JP, Kaun C, Wojta J, Ullrich R, Tretter VE, Markstaller K, Klein KU. Intermittent Hypoxia Causes Inflammation and Injury to Human Adult Cardiac Myocytes. Anesth Analg 2016; 122:373-80. [PMID: 26505576 DOI: 10.1213/ane.0000000000001048] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Intermittent hypoxia may occur in a number of clinical scenarios, including interruption of myocardial blood flow or breathing disorders such as obstructive sleep apnea. Although intermittent hypoxia has been linked to cardiovascular and cerebrovascular disease, the effect of intermittent hypoxia on the human heart is not fully understood. Therefore, in the present study, we compared the cellular responses of cultured human adult cardiac myocytes (HACMs) exposed to intermittent hypoxia and different conditions of continuous hypoxia and normoxia. METHODS HACMs were exposed to intermittent hypoxia (0%-21% O2), constant mild hypoxia (10% O2), constant severe hypoxia (0% O2), or constant normoxia (21% O2), using a novel cell culture bioreactor with gas-permeable membranes. Cell proliferation, lactate dehydrogenase release, vascular endothelial growth factor release, and cytokine (interleukin [IL] and macrophage migration inhibitory factor) release were assessed at baseline and after 8, 24, and 72 hours of exposure. A signal transduction pathway finder array was performed to determine the changes in gene expression. RESULTS In comparison with constant normoxia and constant mild hypoxia, intermittent hypoxia induced earlier and greater inflammatory response and extent of cell injury as evidenced by lower cell numbers and higher lactate dehydrogenase, vascular endothelial growth factor, and proinflammatory cytokine (IL-1β, IL-6, IL-8, and macrophage migration inhibitory factor) release. Constant severe hypoxia showed more detrimental effects on HACMs at later time points. Pathway analysis demonstrated that intermittent hypoxia primarily altered gene expression in oxidative stress, Wnt, Notch, and hypoxia pathways. CONCLUSIONS Intermittent and constant severe hypoxia, but not constant mild hypoxia or normoxia, induced inflammation and cell injury in HACMs. Cell injury occurred earliest and was greatest after intermittent hypoxia exposure. Our in vitro findings suggest that intermittent hypoxia exposure may produce rapid and substantial damage to the human heart.
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Affiliation(s)
- Jing Wu
- From the *Department of Anesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria; †Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; ‡Unit of Anesthesiology and Perioperative Intensive Care, University of Veterinary Medicine, Vienna, Austria; §Department of Internal Medicine II and ‖Core Facilities, Medical University of Vienna, Vienna, Austria; and ¶Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
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16
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Chen R, Formenti F, McPeak H, Obeid AN, Hahn C, Farmery A. Experimental investigation of the effect of polymer matrices on polymer fibre optic oxygen sensors and their time response characteristics using a vacuum testing chamber and a liquid flow apparatus. SENSORS AND ACTUATORS. B, CHEMICAL 2016; 222:531-535. [PMID: 26726286 PMCID: PMC4643756 DOI: 10.1016/j.snb.2015.08.095] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 08/19/2015] [Accepted: 08/22/2015] [Indexed: 06/05/2023]
Abstract
Very fast sensors that are able to track rapid changes in oxygen partial pressure (PO2) in the gas and liquid phases are increasingly required in scientific research - particularly in the life sciences. Recent interest in monitoring very fast changes in the PO2 of arterial blood in some respiratory failure conditions is one such example. Previous attempts to design fast intravascular electrochemical oxygen sensors for use in physiology and medicine have failed to meet the criteria that are now required in modern investigations. However, miniature photonic devices are capable of meeting this need. In this article, we present an inexpensive polymer type fibre-optic, oxygen sensor that is two orders of magnitude faster than conventional electrochemical oxygen sensors. It is constructed with biologically inert polymer materials and is both sufficiently small and robust for direct insertion in to a human artery. The sensors were tested and evaluated in both a gas testing chamber and in a flowing liquid test system. The results showed a very fast T90 response time, typically circa 20 ms when tested in the gas phase, and circa 100 ms in flowing liquid.
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Affiliation(s)
- Rongsheng Chen
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Federico Formenti
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Hanne McPeak
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Andrew N. Obeid
- Oxford Optronix Ltd, 19-21, Central 127, Olympic Avenue, Milton Park, Oxford OX14 4SA, UK
| | - Clive Hahn
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Andrew Farmery
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
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17
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Formenti F. Conclusions From Inverse Ratio Ventilation Studied at a Respiratory Rate of 6 Breaths/Minute. Crit Care Med 2015; 43:e323-4. [PMID: 26181130 PMCID: PMC4539574 DOI: 10.1097/ccm.0000000000001062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Federico Formenti
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
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18
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Andrews PL, Sadowitz B, Kollisch-Singule M, Satalin J, Roy S, Snyder K, Gatto LA, Nieman GF, Habashi NM. Alveolar instability (atelectrauma) is not identified by arterial oxygenation predisposing the development of an occult ventilator-induced lung injury. Intensive Care Med Exp 2015. [PMID: 26215818 PMCID: PMC4480795 DOI: 10.1186/s40635-015-0054-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Improperly set mechanical ventilation (MV) with normal lungs can advance lung injury and increase the incidence of acute respiratory distress syndrome (ARDS). A key mechanism of ventilator-induced lung injury (VILI) is an alteration in alveolar mechanics including alveolar instability or recruitment/derecruitment (R/D). We hypothesize that R/D cannot be identified by PaO2 (masking occult VILI), and if protective ventilation is not applied, ARDS incidence will increase. METHODS Sprague-Dawley rats (n = 8) were anesthetized, surgically instrumented, and placed on MV. A thoracotomy was performed and an in vivo microscope attached to the pleural surface of the lung with baseline dynamic changes in alveolar size during MV recorded. Alveolar instability was induced by intra-tracheal instillation of Tween and alveolar R/D identified as a marked change in alveolar size from inspiration to expiration with increases in positive end-expiratory pressure (PEEP) levels. RESULTS Despite maintaining a clinically acceptable PaO2 (55-80 mmHg), the alveoli remained unstable with significant R/D at low PEEP levels. Although PaO2 consistently increased with an increase in PEEP, R/D did not plateau until PEEP was >9 cmH2O. CONCLUSIONS PaO2 remained clinically acceptable while alveolar instability persisted at all levels of PEEP (especially PEEP <9 cmH2O). Therefore, PaO2 levels cannot be used reliably to guide protective MV strategies or infer that VILI is not occurring. Using PaO2 to set a PEEP level necessary to stabilize the alveoli could underestimate the potential for VILI. These findings highlight the need for more accurate marker(s) of alveolar stability to guide protective MV necessary to prevent VILI.
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Affiliation(s)
- Penny L Andrews
- Department of Critical Care, R Adams Cowley Shock Trauma Center, Baltimore, MD, USA,
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19
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Ovadia-Blechman Z, Meilin A, Rabin N, Eldar M, Castel D. Noninvasive monitoring of peripheral microcirculatory hemodynamics under varying degrees of hypoxia. Respir Physiol Neurobiol 2015; 216:23-7. [PMID: 26006296 DOI: 10.1016/j.resp.2015.05.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 04/21/2015] [Accepted: 05/18/2015] [Indexed: 10/23/2022]
Abstract
The effect of hypoxia on skin blood flow was examined in anesthetized rabbits during induction of various levels of hypoxia. Peripheral perfusion and oxygenation were monitoring using a combined system (LPT) composed of a laser Doppler flowmeter (LDF), a photoplatysmograph (PPG), and a transcutaneous oxygen tension monitor (tc-PO2). Central blood parameters (PaO2, HCO3(-), SaO2, pH, and lactate) were measured concomitantly throughout the experiment. A continuous decline was found in both peripheral and central values, depending on the severity of the hypoxia. The results clearly indicate that monitoring peripheral indices with the LPT system enables monitoring changes of vital blood parameters during hypoxia. The system has clinical potential for sensitive and noninvasive monitoring of vital variables during medical procedures in clinics, as well as for homecare for patients with respiratory diseases. Minimizing the system may be useful in various conditions of exposure to low oxygen levels, such as during mountain climbing.
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Affiliation(s)
- Zehava Ovadia-Blechman
- Department of Medical Engineering, Afeka Tel Aviv Academic College of Engineering, Tel Aviv, Israel.
| | - Aviram Meilin
- Department of Medical Engineering, Afeka Tel Aviv Academic College of Engineering, Tel Aviv, Israel
| | - Neta Rabin
- Department of Exact Sciences, Afeka Tel Aviv Academic College of Engineering, Tel Aviv, Israel
| | - Michael Eldar
- Neufeld Cardiac Research Institute, Tel Aviv University, Sheba Medical Center, Tel-Hashomer, Israel
| | - David Castel
- Neufeld Cardiac Research Institute, Tel Aviv University, Sheba Medical Center, Tel-Hashomer, Israel
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20
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Formenti F, Chen R, McPeak H, Murison PJ, Matejovic M, Hahn CEW, Farmery AD. Intra-breath arterial oxygen oscillations detected by a fast oxygen sensor in an animal model of acute respiratory distress syndrome. Br J Anaesth 2015; 114:683-8. [PMID: 25631471 PMCID: PMC4364062 DOI: 10.1093/bja/aeu407] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background There is considerable interest in oxygen partial pressure (Po2) monitoring in physiology, and in tracking Po2 changes dynamically when it varies rapidly. For example, arterial Po2 (PaO2) can vary within the respiratory cycle in cyclical atelectasis (CA), where PaO2 is thought to increase and decrease during inspiration and expiration, respectively. A sensor that detects these PaO2 oscillations could become a useful diagnostic tool of CA during acute respiratory distress syndrome (ARDS). Methods We developed a fibreoptic Po2 sensor (<200 µm diameter), suitable for human use, that has a fast response time, and can measure Po2 continuously in blood. By altering the inspired fraction of oxygen (FIO2) from 21 to 100% in four healthy animal models, we determined the linearity of the sensor's signal over a wide range of PaO2 values in vivo. We also hypothesized that the sensor could measure rapid intra-breath PaO2 oscillations in a large animal model of ARDS. Results In the healthy animal models, PaO2 responses to changes in FIO2 were in agreement with conventional intermittent blood-gas analysis (n=39) for a wide range of PaO2 values, from 10 to 73 kPa. In the animal lavage model of CA, the sensor detected PaO2 oscillations, also at clinically relevant PaO2 levels close to 9 kPa. Conclusions We conclude that these fibreoptic PaO2 sensors have the potential to become a diagnostic tool for CA in ARDS.
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Affiliation(s)
- F Formenti
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - R Chen
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - H McPeak
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - P J Murison
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - M Matejovic
- Biomedical Centre, Charles University in Prague, Faculty of Medicine in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic First Medical Department, Charles University in Prague, Faculty of Medicine in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic
| | - C E W Hahn
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - A D Farmery
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
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21
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Formenti F, Farmery AD, Hahn CEW. Response to Baumgardner et al. Respir Physiol Neurobiol 2014; 196:38. [PMID: 24583206 DOI: 10.1016/j.resp.2014.01.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 01/12/2014] [Indexed: 10/25/2022]
Affiliation(s)
- Federico Formenti
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.
| | - Andrew D Farmery
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Clive E W Hahn
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
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22
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Large changes in PaO2 oscillation amplitude with respiratory rate are not measurement artifact. Respir Physiol Neurobiol 2014; 195:59. [PMID: 24456732 DOI: 10.1016/j.resp.2014.01.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 01/12/2014] [Indexed: 11/21/2022]
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