1
|
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.
Collapse
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
| |
Collapse
|
2
|
Kadwa AR, Grace JF, Zeiler GE. Sources of error in acid-base analysis from a blood gas analyser result: a narrative review. J S Afr Vet Assoc 2022; 93:89-98. [DOI: 10.36303/jsava.163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Affiliation(s)
- AR Kadwa
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria,
South Africa
- Section of Anaesthesia and Critical Care, Valley Farm Animal Hospital,
South Africa
| | - JF Grace
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria,
South Africa
- Section of Anaesthesia and Critical Care, Valley Farm Animal Hospital,
South Africa
| | - GE Zeiler
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria,
South Africa
- Section of Anaesthesia and Critical Care, Valley Farm Animal Hospital,
South Africa
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
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.
Collapse
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
| | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
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]
|
7
|
Cyclic recruitment of atelectasis – Are there implications for our clinical practice? TRENDS IN ANAESTHESIA AND CRITICAL CARE 2013. [DOI: 10.1016/j.tacc.2013.02.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
8
|
Eatwell K, Mancinelli E, Hedley J, Benato L, Shaw DJ, Self I, Meredith A. Use of arterial blood gas analysis as a superior method for evaluating respiratory function in pet rabbits (Oryctolagus cuniculus). Vet Rec 2013; 173:166. [PMID: 23845942 DOI: 10.1136/vr.101218] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
A retrospective study compared invasive (arterial blood gas analysis) and non-invasive (capnography and pulse oximetry) methods of monitoring respiratory function in conscious rabbits. Arterial samples from 50 healthy dwarf lop rabbits, presenting for routine surgical neutering, were analysed on a point-of-care blood gas analysis machine. Reference intervals were obtained for pH (7.35-7.54), PaCO2 (mm Hg) (25.29-40.37), PaO2 (mm Hg) (50.3-98.2), base excess (mmol/l) (6.7-6.5), HCO3 (mmol/l) (17.96-29.41), TCO2 (mmol/l) (18.9-30.5). SaO2 (per cent) (88.8-98.0), Na (mmol/l) (137.6-145.2), K (mmol/l) (3.28-4.87), iCal (mmol/l) (1.64-1.94), glucose (mmol/l) (6.23-10.53), haematocrit (per cent) (23.3-40.2) and haemoglobin (mg/dl) (7.91-13.63). Pulse oximetry (SPO2) and capnography (ETCO2) readings were taken concurrently. There was no statistically significant relationship between SPO2 and SaO2 with a mean difference between SPO2 and SaO2 of 8.22 per cent. There was a statistically significant relationship between ETCO2 vs PaCO2, but a wide range of ETCO2 values were observed for a given PaCO2. The mean difference between these was 16.16 mm Hg. The study has provided reference intervals for arterial blood gas analysis in rabbits and demonstrated that capnography and pulse oximetry readings should not be relied upon in conscious rabbits as a guide to ventilation and oxygenation.
Collapse
Affiliation(s)
- K Eatwell
- From the Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Hospital for Small Animals, Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG, Scotland
| | | | | | | | | | | | | |
Collapse
|
9
|
Klein K, Boehme S, Hartmann E, Szczyrba M, Heylen L, Liu T, David M, Werner C, Markstaller K, Engelhard K. Transmission of arterial oxygen partial pressure oscillations to the cerebral microcirculation in a porcine model of acute lung injury caused by cyclic recruitment and derecruitment. Br J Anaesth 2013; 110:266-73. [DOI: 10.1093/bja/aes376] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
10
|
Bodenstein M, Bierschock S, Boehme S, Wang H, Vogt A, Kwiecien R, David M, Markstaller K. Influence of fluid and volume state on PaO2oscillations in mechanically ventilated pigs. Exp Lung Res 2013; 39:80-90. [DOI: 10.3109/01902148.2012.758192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
11
|
Hartmann EK, Boehme S, Bentley A, Duenges B, Klein KU, Elsaesser A, Baumgardner JE, David M, Markstaller K. Influence of respiratory rate and end-expiratory pressure variation on cyclic alveolar recruitment in an experimental lung injury model. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2012; 16:R8. [PMID: 22248044 PMCID: PMC3396238 DOI: 10.1186/cc11147] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/04/2011] [Accepted: 01/16/2012] [Indexed: 01/11/2023]
Abstract
Introduction Cyclic alveolar recruitment/derecruitment (R/D) is an important mechanism of ventilator-associated lung injury. In experimental models this process can be measured with high temporal resolution by detection of respiratory-dependent oscillations of the paO2 (ΔpaO2). A previous study showed that end-expiratory collapse can be prevented by an increased respiratory rate in saline-lavaged rabbits. The current study compares the effects of increased positive end-expiratory pressure (PEEP) versus an individually titrated respiratory rate (RRind) on intra-tidal amplitude of Δ paO2 and on average paO2 in saline-lavaged pigs. Methods Acute lung injury was induced by bronchoalveolar lavage in 16 anaesthetized pigs. R/D was induced and measured by a fast-responding intra-aortic probe measuring paO2. Ventilatory interventions (RRind (n = 8) versus extrinsic PEEP (n = 8)) were applied for 30 minutes to reduce Δ paO2. Haemodynamics, spirometry and Δ paO2 were monitored and the Ventilation/Perfusion distributions were assessed by multiple inert gas elimination. The main endpoints average and Δ paO2 following the interventions were analysed by Mann-Whitney-U-Test and Bonferroni's correction. The secondary parameters were tested in an explorative manner. Results Both interventions reduced Δ paO2. In the RRind group, ΔpaO2 was significantly smaller (P < 0.001). The average paO2 continuously decreased following RRind and was significantly higher in the PEEP group (P < 0.001). A sustained difference of the ventilation/perfusion distribution and shunt fractions confirms these findings. The RRind application required less vasopressor administration. Conclusions Different recruitment kinetics were found compared to previous small animal models and these differences were primarily determined by kinetics of end-expiratory collapse. In this porcine model, respiratory rate and increased PEEP were both effective in reducing the amplitude of paO2 oscillations. In contrast to a recent study in a small animal model, however, increased respiratory rate did not maintain end-expiratory recruitment and ultimately resulted in reduced average paO2 and increased shunt fraction.
Collapse
Affiliation(s)
- Erik K Hartmann
- Department of Anaesthesiology, Medical Center of the Johannes Gutenberg-University, Mainz 55131, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Assessing gas exchange in acute lung injury/acute respiratory distress syndrome: diagnostic techniques and prognostic relevance. Curr Opin Crit Care 2011; 17:18-23. [PMID: 21157313 DOI: 10.1097/mcc.0b013e32834272d8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW To provide the most recent insights on the assessment of gas exchange in acute lung injury. RECENT FINDINGS Central venous blood may be used as a surrogate of arterial blood to assess carbon dioxide tension and acid-base status. In contrast arterial oxygenation cannot be estimated with confidence from venous blood. However, the use of venous blood associated with pulse oximetry may provide the SvO2 which is useful for monitoring and targeting the resuscitation therapy. Impaired CO2 clearance and increased dead space have been confirmed as useful prognostic indices of structural lung damage and mortality in acute respiratory failure. A simplified technique based on multiple inert gas technique has been described to assess ventilation-perfusion mismatch while a new analysis of pulse oximetry has been suggested to detect lung opening and closing. Finally, new insight has been provided on the relationship between lung anatomy, as detected by computed tomography, oxygenation and CO2 clearance. SUMMARY Although oxygenation assessment is of primary importance during respiratory lung injury, dead space and CO2 retention are more strictly associated with outcome. The association of central venous blood analysis and pulse oximetry may provide more information than arterial blood alone.
Collapse
|
13
|
Shi C, Boehme S, Hartmann EK, Markstaller K. Novel technologies to detect atelectotrauma in the injured lung. Exp Lung Res 2010; 37:18-25. [PMID: 20860539 DOI: 10.3109/01902148.2010.501402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cyclical recruitment and derecruitment of lung parenchyma (R/D) remains a serious problem in ALI/ARDS patients, defined as atelectotrauma. Detection of cyclical R/D to titrate the optimal respiratory settings is of high clinical importance. Image-based technologies that are capable of detecting changes of lung ventilation within a respiratory cycle include dynamic computed tomography (dCT), synchrotron radiation computed tomography (SRCT), and electrical impedance tomography (EIT). Time-dependent intra-arterial oxygen tension monitoring represents an alternative approach to detect cyclical R/D, as cyclical R/D can result in oscillations of PaO₂ within a respiratory cycle. Continuous, ultrafast, on-line in vivo measurement of PaO₂ can be provided by an indwelling PaO₂ probe. In addition, monitoring of fast changes in SaO₂ by pulse oximetry technology at the bedside could also be used to detect those fast changes in oxygenation.
Collapse
Affiliation(s)
- Chang Shi
- Department of Anesthesiology, Medical Center of the Johannes-Gutenberg-University, Mainz, Germany.
| | | | | | | |
Collapse
|
14
|
Bodenstein M, Wang H, Boehme S, Baumgardner JE, Duenges B, Vogt A, David M, Markstaller K. Observation of ventilation-induced Spo(2) oscillations in pigs: first step to noninvasive detection of cyclic recruitment of atelectasis? Exp Lung Res 2010; 36:270-6. [PMID: 20497021 DOI: 10.3109/01902140903575971] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
High arterial partial oxygen pressure (Pao(2)) oscillations within the respiratory cycle were described recently in experimental acute lung injury. This phenomenon has been related to cyclic recruitment of atelectasis and varying pulmonary shunt fractions. Noninvasive detection of Spo(2) (oxygen saturation measured by pulse oximetry) as an indicator of cyclic collapse of atelectasis, instead of recording Pao(2) oscillations, could be of clinical interest in critical care. Spo(2) oscillations were recorded continuously in three different cases of lung damage to demonstrate the technical feasibility of this approach. To deduce Pao(2) from Spo(2), a mathematical model of the hemoglobin dissociation curve including left and right shifts was derived from the literature and adapted to the dynamic changes of oxygenation. Calculated Pao(2) amplitudes (derived from Spo(2) measurements) were compared to simultaneously measured fast changes of Pao(2), using a current standard method (fluorescence quenching of ruthenium). Peripheral hemoglobin saturation was capable to capture changes of Spo(2) within each respiratory cycle. For the first time, Spo(2) oscillations due to cyclic recruitment of atelectasis within a respiratory cycle were determined by photoplethysmography, a technology that can be readily applied noninvasively in clinical routine. A mathematic model to calculate the respective Pao(2) changes was developed and its applicability tested.
Collapse
Affiliation(s)
- Marc Bodenstein
- Department of Anaesthesiology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Hua YM, Lien SH, Liu TY, Lee CM, Yuh YS. A decremental PEEP trial for determining open-lung PEEP in a rabbit model of acute lung injury. Pediatr Pulmonol 2008; 43:371-80. [PMID: 18293413 DOI: 10.1002/ppul.20780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A positive end-expiratory pressure (PEEP) above the lower inflection point (LIP) of the pressure-volume curve has been thought necessary to maintain recruited lung volume in acute lung injury (ALI). We used a strategy to identify the level of open-lung PEEP (OLP) by detecting the maximum tidal compliance during a decremental PEEP trial (DPT). We performed a randomized controlled study to compare the effect of the OLP to PEEP above LIP and zero PEEP on pulmonary mechanics, gas exchange, hemodynamic change, and lung injury in 26 rabbits with ALI. After recruitment maneuver, the lavage-injured rabbits received DPTs to identify the OLP. Animals were randomized to receive volume controlled ventilation with either: (a) PEEP = 0 cm H2O (ZEEP); (b) PEEP = 2 cm H2O above OLP (OLP + 2); or (c) PEEP = 2 cm H2O above LIP (LIP + 2). Peak inspiratory pressure and mean airway pressure were recorded and arterial blood gases were analyzed every 30 min. Mean blood pressure and heart rate were monitored continuously. Lung injury severity was assessed by lung wet/dry weight ratio. Animals in OLP + 2 group had less lung injury as well as relatively better compliance, more stable pH, and less hypercapnia compared to the LIP + 2 and ZEEP groups. We concluded that setting PEEP according to the OLP identified by DPTs is an effective method to attenuate lung injury. This strategy could be used as an indicator for optimal PEEP. The approach is simple and noninvasive and may be of clinical interest.
Collapse
Affiliation(s)
- Yi-Ming Hua
- Department of Pediatrics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | | | | | | | | |
Collapse
|
16
|
Otto CM, Markstaller K, Kajikawa O, Karmrodt J, Syring RS, Pfeiffer B, Good VP, Frevert CW, Baumgardner JE. Spatial and temporal heterogeneity of ventilator-associated lung injury after surfactant depletion. J Appl Physiol (1985) 2008; 104:1485-94. [PMID: 18323462 DOI: 10.1152/japplphysiol.01089.2007] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Volutrauma and atelectrauma have been proposed as mechanisms of ventilator-associated lung injury, but few studies have compared their relative importance in mediating lung injury. The objective of our study was to compare the injury produced by stretch (volutrauma) vs. cyclical recruitment (atelectrauma) after surfactant depletion. In saline-lavaged rabbits, we used high tidal volume, low respiratory rate, and low positive end-expiratory pressure to produce stretch injury in nondependent lung regions and cyclical recruitment in dependent lung regions. Tidal changes in shunt fraction were assessed by measuring arterial Po(2) oscillations. After ventilating for times ranging from 0 to 6 h, lungs were excised, sectioned gravitationally, and assessed for regional injury by evaluation of edema formation, chemokine expression, upregulation of inflammatory enzyme activity, and alveolar neutrophil accumulation. Edema formation, lung tissue interleukin-8 expression, and alveolar neutrophil accumulation progressed more rapidly in dependent lung regions, whereas macrophage chemotactic protein-1 expression progressed more rapidly in nondependent lung regions. Temporal and regional heterogeneity of lung injury were substantial. In this surfactant depletion model of acute lung injury, cyclical recruitment produced more injury than stretch.
Collapse
Affiliation(s)
- Cynthia M Otto
- Departmrnt of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
|
18
|
Musch G, Bellani G, Vidal Melo MF, Harris RS, Winkler T, Schroeder T, Venegas JG. Relation between shunt, aeration, and perfusion in experimental acute lung injury. Am J Respir Crit Care Med 2007; 177:292-300. [PMID: 17932380 DOI: 10.1164/rccm.200703-484oc] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE In a pulmonary process characterized by spatially heterogeneous loss of aeration, the impairment of gas exchange is expected to depend on the regional distribution of perfusion relative to that of aeration. OBJECTIVES To investigate how regional aeration, shunt, and perfusion are interrelated at different levels of end-expiratory pressure and how their interplay relates to global shunt fraction in acute lung injury. METHODS Regional shunt and perfusion were assessed by imaging with positron emission tomography the pulmonary kinetics of [(13)N]nitrogen infused in saline solution in five sheep after lung lavage. The lung field was divided in six horizontal regions. MEASUREMENTS AND MAIN RESULTS Each animal showed an inverse relation between regional shunt (Fs) and gas (Fg) fractions: Fs = -m . Fg + Fs(0). This relation was similar among animals (m = 1.25 +/- 0.14, Fs(0) = 0.75 +/- 0.15) and invariant with end-expiratory pressure, despite lack of correlation between global shunt and gas fractions and large interanimal variability in global shunt fraction. When this relation was used to estimate global shunt fraction as a perfusion-weighted average of the estimates of regional shunt fraction derived from regional gas fraction, 72% of the interanimal variability in global shunt fraction could be explained. CONCLUSIONS Despite large interanimal variability in global shunt fraction, there was a consistent inverse relation between regional shunt and gas fractions, independent of end-expiratory pressure. Most of the interanimal variability in global shunt fraction could be explained by the combined effect of this relation and the distribution of perfusion on regional shunt, rather than by differences in global aeration.
Collapse
Affiliation(s)
- Guido Musch
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
| | | | | | | | | | | | | |
Collapse
|
19
|
Pavone L, Albert S, DiRocco J, Gatto L, Nieman G. Alveolar instability caused by mechanical ventilation initially damages the nondependent normal lung. Crit Care 2007; 11:R104. [PMID: 17877789 PMCID: PMC2556747 DOI: 10.1186/cc6122] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 09/06/2007] [Accepted: 09/18/2007] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Septic shock is often associated with acute respiratory distress syndrome, a serious clinical problem exacerbated by improper mechanical ventilation. Ventilator-induced lung injury (VILI) can exacerbate the lung injury caused by acute respiratory distress syndrome, significantly increasing the morbidity and mortality. In this study, we asked the following questions: what is the effect of the lung position (dependent lung versus nondependent lung) on the rate at which VILI occurs in the normal lung? Will positive end-expiratory pressure (PEEP) slow the progression of lung injury in either the dependent lung or the nondependent lung? MATERIALS AND METHODS Sprague-Dawley rats (n = 19) were placed on mechanical ventilation, and the subpleural alveolar mechanics were measured with an in vivo microscope. Animals were placed in the lateral decubitus position, left lung up to measure nondependent alveolar mechanics and left lung down to film dependent alveolar mechanics. Animals were ventilated with a high peak inspiratory pressure of 45 cmH2O and either a low PEEP of 3 cmH2O or a high PEEP of 10 cmH2O for 90 minutes. Animals were separated into four groups based on the lung position and the amount of PEEP: Group I, dependent + low PEEP (n = 5); Group II, nondependent + low PEEP (n = 4); Group III, dependent + high PEEP (n = 5); and Group IV, nondependent + high PEEP (n = 5). Hemodynamic and lung function parameters were recorded concomitant with the filming of alveolar mechanics. Histological assessment was performed at necropsy to determine the presence of lung edema. RESULTS VILI occurred earliest (60 min) in Group II. Alveolar instability eventually developed in Groups I and II at 75 minutes. Alveoli in both the high PEEP groups were stable for the entire experiment. There were no significant differences in arterial PO2 or in the degree of edema measured histologically among experimental groups. CONCLUSION This open-chest animal model demonstrates that the position of the normal lung (dependent or nondependent) plays a role on the rate of VILI.
Collapse
Affiliation(s)
- Lucio Pavone
- Upstate Medical University, Department of Surgery, 750 E Adams Street, Syracuse, NY 13210 USA
| | - Scott Albert
- Upstate Medical University, Department of Surgery, 750 E Adams Street, Syracuse, NY 13210 USA
| | - Joseph DiRocco
- Upstate Medical University, Department of Surgery, 750 E Adams Street, Syracuse, NY 13210 USA
| | - Louis Gatto
- Department of Biology, Cortland College, P.O. Box 2000 Cortland, NY 13045 USA
| | - Gary Nieman
- Upstate Medical University, Department of Surgery, 750 E Adams Street, Syracuse, NY 13210 USA
| |
Collapse
|
20
|
Syring RS, Otto CM, Spivack RE, Markstaller K, Baumgardner JE. Maintenance of end-expiratory recruitment with increased respiratory rate after saline-lavage lung injury. J Appl Physiol (1985) 2006; 102:331-9. [PMID: 16959915 DOI: 10.1152/japplphysiol.00002.2006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cyclical recruitment of atelectasis with each breath is thought to contribute to ventilator-associated lung injury. Extrinsic positive end-expiratory pressure (PEEPe) can maintain alveolar recruitment at end exhalation, but PEEPe depresses cardiac output and increases overdistension. Short exhalation times can also maintain end-expiratory recruitment, but if the mechanism of this recruitment is generation of intrinsic PEEP (PEEPi), there would be little advantage compared with PEEPe. In seven New Zealand White rabbits, we compared recruitment from increased respiratory rate (RR) to recruitment from increased PEEPe after saline lavage. Rabbits were ventilated in pressure control mode with a fraction of inspired O(2) (Fi(O(2))) of 1.0, inspiratory-to-expiratory ratio of 2:1, and plateau pressure of 28 cmH(2)O, and either 1) high RR (24) and low PEEPe (3.5) or 2) low RR (7) and high PEEPe (14). We assessed cyclical lung recruitment with a fast arterial Po(2) probe, and we assessed average recruitment with blood gas data. We measured PEEPi, cardiac output, and mixed venous saturation at each ventilator setting. Recruitment achieved by increased RR and short exhalation time was nearly equivalent to recruitment achieved by increased PEEPe. The short exhalation time at increased RR, however, did not generate PEEPi. Cardiac output was increased on average 13% in the high RR group compared with the high PEEPe group (P < 0.001), and mixed venous saturation was consistently greater in the high RR group (P < 0.001). Prevention of end-expiratory derecruitment without increased end-expiratory pressure suggests that another mechanism, distinct from intrinsic PEEP, plays a role in the dynamic behavior of atelectasis.
Collapse
Affiliation(s)
- Rebecca S Syring
- Department of Clinical Studies, Section of Critical Care, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | | | | |
Collapse
|