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Impact of Recruitment on Static and Dynamic Lung Strain in Acute Respiratory Distress Syndrome. Anesthesiology 2016; 124:443-52. [PMID: 26569171 DOI: 10.1097/aln.0000000000000946] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Lung strain, defined as the ratio between end-inspiratory volume and functional residual capacity, is a marker of the mechanical load during ventilation. However, changes in lung volumes in response to pressures may occur in injured lungs and modify strain values. The objective of this study was to clarify the role of recruitment in strain measurements. METHODS Six oleic acid-injured pigs were ventilated at positive end-expiratory pressure (PEEP) 0 and 10 cm H2O before and after a recruitment maneuver (PEEP = 20 cm H2O). Lung volumes were measured by helium dilution and inductance plethysmography. In addition, six patients with moderate-to-severe acute respiratory distress syndrome were ventilated with three strategies (peak inspiratory pressure/PEEP: 20/8, 32/8, and 32/20 cm H2O). Lung volumes were measured in computed tomography slices acquired at end-expiration and end-inspiration. From both series, recruited volume and lung strain (total, dynamic, and static) were computed. RESULTS In the animal model, recruitment caused a significant decrease in dynamic strain (from [mean ± SD] 0.4 ± 0.12 to 0.25 ± 0.07, P < 0.01), while increasing the static component. In patients, total strain remained constant for the three ventilatory settings (0.35 ± 0.1, 0.37 ± 0.11, and 0.32 ± 0.1, respectively). Increases in tidal volume had no significant effects. Increasing PEEP constantly decreased dynamic strain (0.35 ± 0.1, 0.32 ± 0.1, and 0.04+0.03, P < 0.05) and increased static strain (0, 0.06 ± 0.06, and 0.28 ± 0.11, P < 0.05). The changes in dynamic and total strain among patients were correlated to the amount of recruited volume. An analysis restricted to the changes in normally aerated lung yielded similar results. CONCLUSION Recruitment causes a shift from dynamic to static strain in early acute respiratory distress syndrome.
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López-Aguilar J, Lucangelo U, Albaiceta GM, Nahum A, Murias G, Cañizares R, Oliva JC, Romero PV, Blanch L. Effects on lung stress of position and different doses of perfluorocarbon in a model of ARDS. Respir Physiol Neurobiol 2015; 210:30-7. [PMID: 25662756 DOI: 10.1016/j.resp.2015.01.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 01/22/2015] [Accepted: 01/30/2015] [Indexed: 01/09/2023]
Abstract
We determined whether the combination of low dose partial liquid ventilation (PLV) with perfluorocarbons (PFC) and prone positioning improved lung function while inducing minimal stress. Eighteen pigs with acute lung injury were assigned to conventional mechanical ventilation (CMV) or PLV (5 or 10 ml/kg of PFC). Positive end-expiratory pressure (PEEP) trials in supine and prone positions were performed. Data were analyzed by a multivariate polynomial regression model. The interplay between PLV and position depended on the PEEP level. In supine PLV dampened the stress induced by increased PEEP during the trial. The PFC dose of 5 ml/kg was more effective than the dose 10 ml/kg. This effect was not observed in prone. Oxygenation was significantly higher in prone than in supine position mainly at lower levels of PEEP. In conclusion, MV settings should take both gas exchange and stress/strain into account. When protective CMV fails, rescue strategies combining prone positioning and PLV with optimal PEEP should improve gas exchange with minimal stress.
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Affiliation(s)
- Josefina López-Aguilar
- Fundació Parc Taulí, Corporació Sanitària Parc Taulí, Sabadell, Spain; Institut de Investigació i Innovació Parc Taulí, Universitat Autònoma de Barcelona, Campus d' Excelència Internacional, Bellaterra, Spain; Critical Care Center, Hospital de Sabadell, Corporació Sanitària Parc Taulí, Sabadell, Spain; CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
| | - Umberto Lucangelo
- Department of Perioperative Medicine, Intensive Care and Emergency, Cattinara Hospital, Trieste University, Trieste, Italy
| | - Guillermo M Albaiceta
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain; Dpto. Biologia Funcional, Universidad de Oviedo, Instituto Universitario de Oncologia del Principado de Asturias, Oviedo, Spain; Intensive Care Unit, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Avi Nahum
- Pulmonary and Critical Care Department, St. Paul-Ramsey Medical Center, University of Minnesota, St. Paul, MN, USA
| | - Gastón Murias
- Clínica Bazterrica y Clínica Santa Isabel, Buenos Aires, Argentina
| | | | - Joan Carles Oliva
- Fundació Parc Taulí, Corporació Sanitària Parc Taulí, Sabadell, Spain; Institut de Investigació i Innovació Parc Taulí, Universitat Autònoma de Barcelona, Campus d' Excelència Internacional, Bellaterra, Spain
| | - Pablo V Romero
- Laboratory of Experimental Pneumology, IDIBELL, L'Hospitalet, Spain
| | - Lluís Blanch
- Fundació Parc Taulí, Corporació Sanitària Parc Taulí, Sabadell, Spain; Institut de Investigació i Innovació Parc Taulí, Universitat Autònoma de Barcelona, Campus d' Excelència Internacional, Bellaterra, Spain; Critical Care Center, Hospital de Sabadell, Corporació Sanitària Parc Taulí, Sabadell, Spain; CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
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Monitoring Lung Volumes During Mechanical Ventilation. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7193716 DOI: 10.1007/978-3-642-01219-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Respiratory inductive plethysmography (RIP) is a non-invasive method of measuring change in lung volume which is well-established as a monitor of tidal ventilation and thus respiratory patterns in sleep medicine. As RIP is leak independent, can measure end-expiratory lung volume as well as tidal volume and is applicable to both the ventilated and spontaneously breathing patient, there has been a recent interest in its use as a bedside tool in the intensive care unit.
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The Clinical Utilisation of Respiratory Elastance Software (CURE Soft): a bedside software for real-time respiratory mechanics monitoring and mechanical ventilation management. Biomed Eng Online 2014; 13:140. [PMID: 25270094 PMCID: PMC4192763 DOI: 10.1186/1475-925x-13-140] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/20/2014] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Real-time patient respiratory mechanics estimation can be used to guide mechanical ventilation settings, particularly, positive end-expiratory pressure (PEEP). This work presents a software, Clinical Utilisation of Respiratory Elastance (CURE Soft), using a time-varying respiratory elastance model to offer this ability to aid in mechanical ventilation treatment. IMPLEMENTATION CURE Soft is a desktop application developed in JAVA. It has two modes of operation, 1) Online real-time monitoring decision support and, 2) Offline for user education purposes, auditing, or reviewing patient care. The CURE Soft has been tested in mechanically ventilated patients with respiratory failure. The clinical protocol, software testing and use of the data were approved by the New Zealand Southern Regional Ethics Committee. RESULTS AND DISCUSSION Using CURE Soft, patient's respiratory mechanics response to treatment and clinical protocol were monitored. Results showed that the patient's respiratory elastance (Stiffness) changed with the use of muscle relaxants, and responded differently to ventilator settings. This information can be used to guide mechanical ventilation therapy and titrate optimal ventilator PEEP. CONCLUSION CURE Soft enables real-time calculation of model-based respiratory mechanics for mechanically ventilated patients. Results showed that the system is able to provide detailed, previously unavailable information on patient-specific respiratory mechanics and response to therapy in real-time. The additional insight available to clinicians provides the potential for improved decision-making, and thus improved patient care and outcomes.
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Positive end expiratory pressure in patients with acute respiratory distress syndrome – The past, present and future. Biomed Signal Process Control 2012. [DOI: 10.1016/j.bspc.2011.03.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Correger E, Murias G, Chacon E, Estruga A, Sales B, Lopez-Aguilar J, Montanya J, Lucangelo U, Garcia-Esquirol O, Villagra A, Villar J, Kacmarek RM, Burgueño MJ, Blanch L. [Interpretation of ventilator curves in patients with acute respiratory failure]. Med Intensiva 2011; 36:294-306. [PMID: 22014424 DOI: 10.1016/j.medin.2011.08.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 08/08/2011] [Accepted: 08/30/2011] [Indexed: 11/17/2022]
Abstract
Mechanical ventilation is a therapeutic intervention involving the temporary replacement of ventilatory function with the purpose of improving symptoms in patients with acute respiratory failure. Technological advances have facilitated the development of sophisticated ventilators for viewing and recording the respiratory waveforms, which are a valuable source of information for the clinician. The correct interpretation of these curves is crucial for the correct diagnosis and early detection of anomalies, and for understanding physiological aspects related to mechanical ventilation and patient-ventilator interaction. The present study offers a guide for the interpretation of the airway pressure and flow and volume curves of the ventilator, through the analysis of different clinical scenarios.
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Affiliation(s)
- E Correger
- Grupo de Trabajo en Fisiopatología Pulmonar Experimental, Cátedra de Fisiología, FCM, UNLP, Hospital El Cruce y Fundación Favaloro, Buenos Aires, Argentina
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[The basics on mechanical ventilation support in acute respiratory distress syndrome]. Med Intensiva 2010; 34:418-27. [PMID: 20097448 DOI: 10.1016/j.medin.2009.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 10/14/2009] [Accepted: 10/21/2009] [Indexed: 01/05/2023]
Abstract
Acute Respiratory Distress Syndrome (ARDS) is understood as an inflammation-induced disruption of the alveolar endothelial-epithelial barrier that results in increased permeability and surfactant dysfunction followed by alveolar flooding and collapse. ARDS management relies on mechanical ventilation. The current challenge is to determine the optimal ventilatory strategies that minimize ventilator-induced lung injury (VILI) while providing a reasonable gas exchange. The data support that a tidal volume between 6-8 ml/kg of predicted body weight providing a plateau pressure < 30 cmH₂O should be used. High positive end expiratory pressure (PEEP) has not reduced mortality, nevertheless secondary endpoints are improved. The rationale used for high PEEP argues that it prevents cyclic opening and closing of airspaces, probably the major culprit of development of VILI. Chest computed tomography has contributed to our understanding of anatomic-functional distribution patterns in ARDS. Electric impedance tomography is a technique that is radiation-free, but still under development, that allows dynamic monitoring of ventilation distribution at bedside.
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Markhorst DG, Van Gestel JP, Van Genderingen HR, Haitsma JJ, Lachmann B, Van Vught AJ. Respiratory inductive plethysmography accuracy at varying PEEP levels and degrees of acute lung injury. J Med Eng Technol 2009; 30:166-75. [PMID: 16772220 DOI: 10.1080/03091900500529826] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND AND OBJECTIVE This study was performed to assess the accuracy of respiratory inductive plethysmographic (RIP) estimated lung volume changes at varying positive end-expiratory pressures (PEEP) during different degrees of acute respiratory failure. METHODS Measurements of inspiratory tidal volume were validated in eight piglets during constant volume ventilation at incremental and decremental PEEP levels and with increasing severity of pulmonary injury. RIP accuracy was assessed with calibration from the healthy state, from the disease state as the measurement error was assessed, and at various PEEP levels. RESULTS Best results (bias 3%, precision 7%) were obtained in healthy animals. RIP accuracy decreased with progressing degrees of acute respiratory failure and was PEEP dependent, unless RIP was calibrated again. When calibration was performed in the disease state as the measurement error was assessed, bias was reduced but precision did not improve (bias -2%, precision 9%). CONCLUSIONS RIP accuracy is within the accuracy range found in monitoring devices currently in clinical use. Most reliable results with RIP are obtained when measurements are preceded by calibration in pulmonary conditions that are comparable to the measurement period. When RIP calibration is not possible, fixed weighting of the RIP signals with species and subject size adequate factors is an alternative. Measurement errors should be taken into account with interpretation of small volume changes.
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Affiliation(s)
- D G Markhorst
- Pediatric Intensive Care Unit, University Medical Center Utrecht, Utrecht, The Netherlands.
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Piacentini E, Wysocki M, Blanch L. A new automated method versus continuous positive airway pressure method for measuring pressure-volume curves in patients with acute lung injury. Intensive Care Med 2008; 35:565-70. [PMID: 18853137 DOI: 10.1007/s00134-008-1322-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 09/20/2008] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To compare pressure-volume (P-V) curves obtained with the Galileo ventilator with those obtained with the CPAP method in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). DESIGN Prospective, observational study. SETTING General critical care center. PATIENTS AND PARTICIPANTS Patients with ALI/ARDS and receiving mechanical ventilation. INTERVENTIONS Pressure-volume curves were obtained in random order with the CPAP technique and with the software PV Tool-2 (Galileo ventilator). MEASUREMENTS AND RESULTS In ten consecutive patients, airway pressure was measured by a pressure transducer and changes in lung volume were measured by respiratory inductive plethysmography. P-V curves were fitted to a sigmoidal equation with a mean R (2) of 0.994 +/- 0.003. Intraclass correlation coefficients were all >0.75 (P < 0.001 at all pressure levels). Lower (LIP) and upper inflection (UIP), and deflation maximum curvature (PMC) points calculated from the fitted variables showed a good correlation between methods with intraclass correlation coefficients of 0.98 (0.92, 0.99), 0.92 (0.69, 0.98), and 0.97 (0.86, 0.98), respectively (P < 0.001 in all cases). Bias and limits of agreement for LIP (0.51 +/- 0.95 cmH(2)O; -1.36 to 2.38 cmH(2)O), UIP (0.53 +/- 1.52 cmH(2)O; -2.44 to 3.50 cmH(2)O), and PMC (-0.62 +/- 0.89 cmH(2)O; -2.35 to 1.12 cmH(2)O) obtained with the two methods in the same patient were clinically acceptable. No adverse effects were observed. CONCLUSION The PV Tool-2 built into the Galileo ventilator is equivalent to the CPAP method for tracing static P-V curves of the respiratory system in critically ill patients receiving mechanical ventilation.
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Affiliation(s)
- Enrique Piacentini
- Doctorando UAB, Intensive Care Unit, Hospital Mútua de Terrassa, Terrassa, Spain
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Blanch L, López-Aguilar J, Villagrá A. Bedside evaluation of pressure-volume curves in patients with acute respiratory distress syndrome. Curr Opin Crit Care 2008; 13:332-7. [PMID: 17468567 DOI: 10.1097/mcc.0b013e32811e14f2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW To describe the physiologic and diagnostic utility of static pressure-volume curves of the respiratory system at the bedside in patients with acute lung injury or acute respiratory distress syndrome. RECENT FINDINGS The pressure-volume curve of the respiratory system is a useful tool for the measurement of respiratory system mechanics in patients with acute lung injury or acute respiratory distress syndrome. The pressure-volume curve has a sigmoid shape, with lower and upper points on the inspiratory limb and a point of maximum curvature on the expiratory limb. Visual and mathematical pressure-volume curve analysis may be useful for understanding individual lung mechanics and for selecting ventilator settings. Among the different techniques for acquiring pressure-volume curves at the bedside, the constant slow flow method is the simplest to perform, the most clinically reliable and has the fewest limitations. SUMMARY Measurement of pressure-volume curves at the bedside in critically ill patients with acute lung injury or acute respiratory distress syndrome should be considered a useful respiratory monitoring tool to assess physiologic lung status and to adjust ventilator settings, when appropriate, to minimize superimposed lung injury associated with mechanical ventilators.
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Affiliation(s)
- Lluis Blanch
- Critical Care Center, Hospital de Sabadell, Institut Universitari Fundació Parc Taulí, Universitat Autónoma de Barcelona, Sabadell, Spain.
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Albaiceta GM, Blanch L, Lucangelo U. Static pressure–volume curves of the respiratory system: were they just a passing fad? Curr Opin Crit Care 2008; 14:80-6. [DOI: 10.1097/mcc.0b013e3282f2b8f4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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LaFollette R, Hojnowski K, Norton J, DiRocco J, Carney D, Nieman G. Using pressure-volume curves to set proper PEEP in acute lung injury. Nurs Crit Care 2007; 12:231-41. [PMID: 17883616 DOI: 10.1111/j.1478-5153.2007.00224.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The evolution of respiratory care on patients with acute respiratory distress syndrome (ARDS) has been focused on preventing the deleterious effects of mechanical ventilation, termed ventilator-induced lung injury (VILI). Currently, reduced tidal volume is the standard of ventilatory care for patients with ARDS. The current focus, however, has shifted to the proper setting of positive end-expiratory pressure (PEEP). The whole lung pressure-volume (P/V) curve has been used to individualize setting proper PEEP in patients with ARDS, although the physiologic interpretation of the curve remains under debate. The purpose of this review is to present the pros and cons of using P/V curves to set PEEP in patients with ARDS. A systematic analysis of recent and relevant literature was conducted. It has been hypothesized that proper PEEP can be determined by identifying P/V curve inflection points. Acquiring a dynamic curve presents the key to the curve's bedside application. The lower inflection point of the inflation limb has been shown to be the point of massive alveolar recruitment and therefore an option for setting PEEP. However, it is becoming widely accepted that the upper inflection point (UIP) of the deflation limb of the P/V curve represents the point of optimal PEEP. New methods used to identify optimal PEEP, including tomography and active compliance measurements, are currently being investigated. In conclusion, we believe that the most promising method for determining proper PEEP settings is use of the UIP of the deflation limb. However, tomography and dynamic compliance may offer superior bedside availability.
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Albaiceta GM, Garcia E, Taboada F. Comparative study of four sigmoid models of pressure-volume curve in acute lung injury. Biomed Eng Online 2007; 6:7. [PMID: 17300715 PMCID: PMC1802870 DOI: 10.1186/1475-925x-6-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Accepted: 02/14/2007] [Indexed: 11/25/2022] Open
Abstract
Background The pressure-volume curve of the respiratory system is a tool to monitor and set mechanical ventilation in acute lung injury. Mathematical models of the static pressure-volume curve of the respiratory system have been proposed to overcome the inter- and intra-observer variability derived from eye-fitting. However, different models have not been compared. Methods The goodness-of-fit and the values of derived parameters (upper asymptote, maximum compliance and points of maximum curvature) in four sigmoid models were compared, using pressure-volume data from 30 mechanically ventilated patients during the early phase of acute lung injury. Results All models showed an excellent goodness-of-fit (R2 always above 0.92). There were significant differences between the models in the parameters derived from the inspiratory limb, but not in those derived from the expiratory limb of the curve. The within-case standard deviations of the pressures at the points of maximum curvature ranged from 2.33 to 6.08 cmH2O. Conclusion There are substantial variabilities in relevant parameters obtained from the four different models of the static pressure-volume curve of the respiratory system.
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Affiliation(s)
- Guillermo M Albaiceta
- Intensive Care Unit, Hospital Universitario Central de Asturias, Oviedo, Spain
- Department of Functional Biology, University of Oviedo, Oviedo, Spain
| | - Esteban Garcia
- Intensive Care Unit, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Francisco Taboada
- Intensive Care Unit, Hospital Universitario Central de Asturias, Oviedo, Spain
- Department of Medicine, University of Oviedo, Oviedo, Spain
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Zhao Y, Rees SE, Kjaergaard S, Smith BW, Larsson A, Andreassen S. An automated method for measuring static pressure–volume curves of the respiratory system and its application in healthy lungs and after lung damage by oleic acid infusion. Physiol Meas 2007; 28:235-47. [PMID: 17322589 DOI: 10.1088/0967-3334/28/3/001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Elastic pressure/volume (PV) curves of the respiratory system have attracted increasing interest, because they may be helpful to optimize ventilator settings in patients undergoing mechanical ventilation. Clinically applicable methods need to be fast, use routinely available equipment, draw the inspiratory and expiratory PV curve limbs, separate the resistive and viscoelastic properties of the respiratory system from the elastic properties, and provide reproducible measurements. This paper presents a computer-controlled method for rapid measurements of static PV curves using a long inflation-deflation with pauses, and its evaluation in six pigs before and after lung damage caused by oleic acid. The method is fast, i.e. 20.5 +/- 1.9 s (mean +/- SD) in healthy lungs and 17.7 +/- 4.1 s in diseased lungs, this including inspiratory and expiratory pauses of 1.1 s duration. In addition the only equipment used was a clinical ventilator and a PC. For healthy and damaged lungs expiratory PV curve limbs were very reproducible and were at higher volume than the inspiratory limbs, indicating hysteresis. For damaged lungs inspiratory PV limbs were reproducible. For healthy lungs the inspiratory limbs were reproducible but only after the first inflation-deflation. It is possible that during the first inflation alveoli are recruited which are not derecruited on deflation, shifting the inspiratory limb of the PV curve. The paused long inflation-deflation technique provides a quick, automated measurement of static PV curves on both inspiratory and expiratory limbs using routinely available equipment in the intensive care unit.
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Affiliation(s)
- Y Zhao
- Center for Model-Based Medical Decision Support, Institute for Health Science and Technology, Aalborg University, Niels Jernes Vej 14, 4-311, Aalborg East, Denmark
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López-Aguilar J, Piacentini E, Villagrá A, Murias G, Pascotto S, Saenz-Valiente A, Fernández-Segoviano P, Hotchkiss JR, Blanch L. Contributions of vascular flow and pulmonary capillary pressure to ventilator-induced lung injury. Crit Care Med 2006; 34:1106-12. [PMID: 16484897 DOI: 10.1097/01.ccm.0000205757.66971.da] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the influence of vascular flow on ventilator-induced lung injury independent of vascular pressures. DESIGN Laboratory study. SETTING Hospital laboratory. SUBJECTS Thirty-two New Zealand White rabbits. INTERVENTIONS Thirty-two isolated perfused rabbit lungs were allocated into four groups: low flow/low pulmonary capillary pressure; high flow/high pulmonary capillary pressure; low flow/high pulmonary capillary pressure, and high flow/low pulmonary capillary pressure. All lungs were ventilated with peak airway pressure 30 cm H2O and positive end-expiratory pressure 5 cm H2O for 30 mins. MEASUREMENTS AND MAIN RESULTS Outcome measures included frequency of gross structural failure (pulmonary rupture), pulmonary hemorrhage, edema formation, changes in lung compliance, pulmonary vascular resistance, and pulmonary ultrafiltration coefficient. Lungs exposed to high pulmonary vascular flow ruptured more frequently, displayed more hemorrhage, developed more edema, suffered larger decreases in compliance, and had larger increases in vascular resistance than lungs exposed to low vascular flows (p < .05 for each pairwise comparison between groups). CONCLUSIONS These findings suggest that high pulmonary vascular flows might exacerbate ventilator-induced lung injury independent of their effects on pulmonary vascular pressures.
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Affiliation(s)
- Josefina López-Aguilar
- Critical Care Center, Hospital de Sabadell, Institut Universitari Parc Taulí, Universitat Autónoma de Barcelona, Esfera UAB, Spain
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Tingay DG, Mills JF, Morley CJ, Pellicano A, Dargaville PA. The Deflation Limb of the Pressure–Volume Relationship in Infants during High-Frequency Ventilation. Am J Respir Crit Care Med 2006; 173:414-20. [PMID: 16322649 DOI: 10.1164/rccm.200502-299oc] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE The importance of applying high-frequency oscillatory ventilation with a high lung volume strategy in infants is well established. Currently, a lack of reliable methods for assessing lung volume limits clinicians' ability to achieve the optimum volume range. OBJECTIVES To map the pressure-volume relationship of the lung during high-frequency oscillatory ventilation in infants, to determine at what point ventilation is being applied clinically, and to describe the relationship between airway pressure, lung volume, and oxygenation. METHODS In 12 infants, a partial inflation limb and the deflation limb of the pressure-volume relationship were mapped using a quasi-static lung volume optimization maneuver. This involved stepwise airway pressure increments to total lung capacity, followed by decrements until the closing pressure of the lung was identified. MEASUREMENTS AND MAIN RESULTS Lung volume and oxygen saturation were recorded at each airway pressure. Lung volume was measured using respiratory inductive plethysmography. A distinct deflation limb could be mapped in each infant. Overall, oxygenation and lung volume were improved by applying ventilation on the deflation limb. Maximal lung volume and oxygenation occurred on the deflation limb at a mean airway pressure of 3 and 5 cm H(2)O below the airway pressure approximating total lung capacity, respectively. CONCLUSIONS Using current ventilation strategies, all infants were being ventilated near the inflation limb. It is possible to delineate the deflation limb in infants receiving high-frequency oscillatory ventilation; in doing so, greater lung volume and oxygenation can be achieved, often at lower airway pressures.
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Affiliation(s)
- David G Tingay
- Department of Neonatology, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052, Australia.
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Gattinoni L, Eleonora C, Caironi P. Monitoring of pulmonary mechanics in acute respiratory distress syndrome to titrate therapy. Curr Opin Crit Care 2005; 11:252-8. [PMID: 15928475 DOI: 10.1097/01.ccx.0000160773.43122.35] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW This paper reviews recent findings regarding the respiratory mechanics during acute respiratory distress syndrome as a tool for tailoring its ventilatory management. RECENT FINDINGS The pressure-volume curve has been used for many years as a descriptor of the respiratory mechanics in patients affected by acute respiratory distress syndrome. The use of the sigmoidal equation introduced by Venegas for the analysis of the pressure-volume curve seems to be the most rigorous mathematical approach to assessing lung mechanics. Increasing attention has been focused on the deflation limb for titration of positive end-expiratory pressure. Based on physiologic reasoning, a novel parameter, the stress index, has been proposed for tailoring a safe mechanical ventilation, although its clinical impact has still to be proved. Evidence has confirmed that a variety of underlying pathologies may lead to acute respiratory distress syndrome, making unrealistic any attempt to unify the ventilatory approach. Although extensively proposed to tailor mechanical ventilation during acute respiratory distress syndrome, there is no evidence that the pressure-volume curve may be useful in setting a lung-protective strategy in the presence of different potentials for recruitment. SUMMARY The Venegas approach should be the standard analysis of pressure-volume curves. In any patient, the potential for recruitment should be assessed, as a basis for tailoring the most effective mechanical ventilation. Further studies are needed to clarify the potential use of the pressure-volume curve to guide a lung-protective ventilatory strategy.
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Affiliation(s)
- Luciano Gattinoni
- Istituto di Anestesia e Rianimazione, Ospedale Maggiore di Milano-IRCCS, Università degli Studi di Milano, Milano, Italy.
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López-Aguilar J, Villagrá A, Bernabé F, Murias G, Piacentini E, Real J, Fernández-Segoviano P, Romero PV, Hotchkiss JR, Blanch L. Massive brain injury enhances lung damage in an isolated lung model of ventilator-induced lung injury. Crit Care Med 2005; 33:1077-83. [PMID: 15891339 DOI: 10.1097/01.ccm.0000162913.72479.f7] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVE To assess the influence of massive brain injury on pulmonary susceptibility to injury attending subsequent mechanical or ischemia/reperfusion stress. DESIGN Prospective experimental study. SETTING Animal research laboratory. SUBJECTS Twenty-four anesthetized New Zealand White rabbits randomized to control (n = 12) or induced brain injury (n = 12) group. INTERVENTIONS After randomization, brain injury was induced by inflation of an intracranial balloon-tipped catheter, and animals were ventilated with a tidal volume of 10 mL/kg and zero end-expiratory pressure for 120 mins. Following heart-lung block extraction, isolated and perfused lungs were subjected to injurious ventilation with peak airway pressure 30 cm H2O and positive end-expiratory pressure 5 cm H2O for 30 mins. MEASUREMENTS AND MAIN RESULTS No difference was observed between groups in gas exchange, lung mechanics, or hemodynamics during the 2-hr in vivo period following induction of brain injury. However, after 30 mins of ex vivo injurious mechanical ventilation, lungs from the brain injury group showed greater change in ultrafiltration coefficient, weight gain, and alveolar hemorrhage (all p < .05). CONCLUSIONS Massive brain injury might increase lung vulnerability to subsequent injurious mechanical or ischemia-reperfusion insults, thereby increasing the risk of clinical posttransplant graft failure.
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Affiliation(s)
- Josefina López-Aguilar
- Hospital de Sabadell, Institut Universitari Parc Taulí, Universitat Autònoma de Barcelona, Spain
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Sáenz-Valiente A, Piacentini E, Villagra García A, López-Aguilar J, Murias G, Hotchkiss J, Blanch Torra L. Papel de la microcirculación en el desarrollo de la lesión pulmonar aguda inducida por la ventilación mecánica. Med Intensiva 2005. [DOI: 10.1016/s0210-5691(05)74232-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Henzler D, Mahnken A, Dembinski R, Waskowiak B, Rossaint R, Kuhlen R. Repeated generation of the pulmonary pressure-volume curve may lead to derecruitment in experimental lung injury. Intensive Care Med 2004; 31:302-10. [PMID: 15592813 DOI: 10.1007/s00134-004-2512-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2003] [Accepted: 11/02/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Measurements from the pulmonary pressure-volume (PV) curve have been proposed to adjust ventilator settings. We investigated the effects of repeated construction of an inflation PV curve implemented in a standard ventilator on recruitment or derecruitment in acutely injured lungs. DESIGN AND SETTING Prospective experimental animal study in eight anesthetized and mechanically ventilated pigs. INTERVENTIONS Acute lung injury was induced by lung lavage and animals were ventilated in volume controlled mode with PEEP 10 cmH(2)O. The PV curve was constructed five times repeatedly by constant pressure rise, after which ventilation with the preset PEEP was resumed immediately. Studies of hemodynamics, lung mechanics, blood gases and computed tomography were carried out before and after maneuvers. MEASUREMENTS AND RESULTS Derecruitment was assessed as an increase in nonaerated lung volume (V(NON)), and V(PEEP) was the end-expiratory volume difference between PEEP and ZEEP. There was a significant decrease in PaO(2) from 90.4+/-33.3 to 70.9+/-36.3 mmHg and a rise in venous admixture from 47.8+/-12.7 to 59.1+/-16.6%. V(PEEP) was reduced from 244 to 202 ml. A corresponding decrease in normally aerated lung volume was observed, while regression analysis revealed increase in V(NON) depending on the amount of preexisting atelectasis. CONCLUSIONS Repeated generation of the PV curve with a readily available tool resulted in worsened oxygenation. Derecruitment of the lungs occurred with loss of PEEP at the start of the maneuver, which could not be recovered by a maximum inflation pressure of 40 cmH(2)O. Repeated use of the investigated tool should be cautioned, and users should consider measures to preserve aerated lung volumes.
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Affiliation(s)
- Dietrich Henzler
- Department of Anesthesiology, Aachen University Hospital, Pauwelsstrasse 30, 52074 Aachen, Germany.
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Albaiceta GM, Taboada F, Parra D, Luyando LH, Calvo J, Menendez R, Otero J. Tomographic Study of the Inflection Points of the Pressure–Volume Curve in Acute Lung Injury. Am J Respir Crit Care Med 2004; 170:1066-72. [PMID: 15317670 DOI: 10.1164/rccm.200312-1644oc] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The inflection points of the pressure-volume curve have been used for setting mechanical ventilation in patients with acute lung injury. However, the lung status at these points has never been specifically addressed. In 12 patients with early lung injury we traced both limbs of the pressure-volume curve by means of a stepwise change in airway pressure, and a computed tomography (CT) scan slice was obtained for every pressure level. Although aeration (increase in normally aerated lung) and recruitment (decrease in nonaerated lung) were parallel and continuous along the pressure axis during inflation, loss of aeration and derecruitment were only significant at pressures below the point of maximum curvature on the deflation limb of the pressure-volume curve. This point was related to a higher amount of normally aerated tissue and a lower amount of nonaerated tissue when compared with the lower inflection point on both limbs of the curve. Aeration at the inflection points was similar in lung injury from pulmonary or extrapulmonary origin. There were no significant changes in hyperinflated lung tissue. These results support the use of the deflation limb of the pressure-volume curve for positive end-expiratory pressure setting in patients with acute lung injury.
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Affiliation(s)
- Guillermo M Albaiceta
- Department of Intensive Medicine, Hospital Universitario Central de Asturias, Oveido, Spain.
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Markhorst DG, van Genderingen HR. Accuracy of Respiratory Inductive Plethysmography in Estimating Lung Volume Changes. Crit Care Med 2004; 32:1241-2; author reply 1242. [PMID: 15190992 DOI: 10.1097/01.ccm.0000124858.73354.ec] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
PURPOSE OF REVIEW To review the changes in mechanical ventilation technology over the past year and identify areas that provide a benefit. RECENT FINDINGS The literature demonstrates a continued effort to improve patient ventilator synchrony though the development of new triggering and cycling methods. These techniques include using new signals and using closed loop techniques to respond to changes in patient breathing pattern. New modes of ventilation continue to be introduced, often without proof of efficacy. Fortunately, clinicians have developed alterations to new modes that improve utility and they continue to study these techniques clinically to determine appropriate use. Monitoring the patient remains an important area of investigation, with a flurry of activity surrounding pressure volume curves of the respiratory system. Finally, new ventilators have been introduced that combine high-end performance with small size and weight, while providing an on-board source of air. SUMMARY Mechanical ventilation is ubiquitous to intensive care. Advances in ventilator technology are rapid, and clinicians must keep abreast of changes in ventilator performance and application.
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Affiliation(s)
- Richard Branson
- Department of Surgery, Division of Trauma & Critical Care, University of Cincinnati, Cincinnati, Ohio, USA.
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