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Almeida MR, Horta JGÁ, de Matos NA, de Souza ABF, Castro TDF, Cândido LDS, Andrade MC, Cangussú SD, Costa GDP, Talvani A, Bezerra FS. The effects of different ventilatory modes in female adult rats submitted to mechanical ventilation. Respir Physiol Neurobiol 2020; 284:103583. [PMID: 33202295 DOI: 10.1016/j.resp.2020.103583] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 10/30/2020] [Accepted: 11/11/2020] [Indexed: 12/15/2022]
Abstract
This study aimed to analyze the effects of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) modes in female Wistar rats. 18 Wistar female adult rats were divided into three groups: control (CG), pressure-controlled ventilation (PCVG), and volume-controlled ventilation (VCVG). PCVG and VCVG were submitted to MV for one hour with a tidal volume (TV) of 8 mL/Kg, respiratory rate of 80 breaths/min, and positive end-expiratory pressure of 0 cmH2O. At the end of the experiment, all animals were euthanized. The neutrophils and lymphocytes influx to lung were higher in VCVG and PCVG compared to CG. The activities of superoxide dismutase, catalase and myeloperoxidase were higher in PCVG compared to CG. There was an increase in lipid peroxidation and protein oxidation in PCVG compared to CG. The levels of CCL3 and CCL5 were higher in PCVG compared to CG. In conclusions, the PCV mode promoted structural changes in the lung parenchyma, redox imbalance and inflammation in healthy adult female rats submitted to MV.
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Affiliation(s)
- Matheus Rocha Almeida
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - Jacques Gabriel Álvares Horta
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil; Department of Clinical Medicine/Pediatrics, School of Medicine, Federal University of Ouro Preto (UFOP), Ouro Preto, MG, Brazil
| | - Natália Alves de Matos
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - Ana Beatriz Farias de Souza
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - Thalles de Freitas Castro
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - Leandro da Silva Cândido
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - Mônica Campos Andrade
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - Sílvia Dantas Cangussú
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - Guilherme de Paula Costa
- Laboratory of Immunobiology of Inflammation (LABIIN), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - André Talvani
- Laboratory of Immunobiology of Inflammation (LABIIN), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil
| | - Frank Silva Bezerra
- Laboratory of Experimental Pathophysiology (LAFEx), Department of Biological Sciences (DECBI), Institute of Exact and Biological Sciences (ICEB), Federal University of Ouro Preto (UFOP), Brazil.
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The effects of pressure- versus volume-controlled ventilation on ventilator work of breathing. Biomed Eng Online 2020; 19:72. [PMID: 32933529 PMCID: PMC7491025 DOI: 10.1186/s12938-020-00815-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 09/04/2020] [Indexed: 12/03/2022] Open
Abstract
Background Measurement of work of breathing (WOB) during mechanical ventilation is essential to assess the status and progress of intensive care patients. Increasing ventilator WOB is known as a risk factor for ventilator-induced lung injury (VILI). In addition, the minimization of WOB is crucial to facilitate the weaning process. Several studies have assessed the effects of varying inspiratory flow waveforms on the patient’s WOB during assisted ventilation, but there are few studies on the different effect of inspiratory flow waveforms on ventilator WOB during controlled ventilation. Methods In this paper, we analyze the ventilator WOB, termed mechanical work (MW) for three common inspiratory flow waveforms both in normal subjects and COPD patients. We use Rohrer’s equation for the resistance of the endotracheal tube (ETT) and lung airways. The resistance of pulmonary and chest wall tissue are also considered. Then, the resistive MW required to overcome each component of the respiratory resistance is computed for square and sinusoidal waveforms in volume-controlled ventilation (VCV), and decelerating waveform of flow in pressure-controlled ventilation (PCV). Results The results indicate that under the constant I:E ratio, a square flow profile best minimizes the MW both in normal subjects and COPD patients. Furthermore, the large I:E ratio may be used to lower MW. The comparison of results shows that ETT and lung airways have the main contribution to resistive MW in normals and COPDs, respectively. Conclusion These findings support that for lowering the MW especially in patients with obstructive lung diseases, flow with square waveforms in VCV, are more favorable than decelerating waveform of flow in PCV. Our analysis suggests the square profile is the best choice from the viewpoint of less MW.
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Pressure-regulated volume control vs. volume control ventilation in healthy and injured rabbit lung. Eur J Anaesthesiol 2016; 33:767-75. [DOI: 10.1097/eja.0000000000000485] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Jiang J, Li B, Kang N, Wu A, Yue Y. Pressure-Controlled Versus Volume-Controlled Ventilation for Surgical Patients: A Systematic Review and Meta-analysis. J Cardiothorac Vasc Anesth 2015; 30:501-14. [PMID: 26395394 DOI: 10.1053/j.jvca.2015.05.199] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Jia Jiang
- Department of Anesthesiology, Beijing Chaoyang Hospital of Capital Medical University, Beijing, China
| | - Bo Li
- Department of Internal Medicine, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Na Kang
- Department of Anesthesiology, Beijing Chaoyang Hospital of Capital Medical University, Beijing, China
| | - Anshi Wu
- Department of Anesthesiology, Beijing Chaoyang Hospital of Capital Medical University, Beijing, China
| | - Yun Yue
- Department of Anesthesiology, Beijing Chaoyang Hospital of Capital Medical University, Beijing, China.
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Ferrando C, García M, Gutierrez A, Carbonell JA, Aguilar G, Soro M, Belda FJ. Effects of different flow patterns and end-inspiratory pause on oxygenation and ventilation in newborn piglets: an experimental study. BMC Anesthesiol 2014; 14:96. [PMID: 25368544 PMCID: PMC4216830 DOI: 10.1186/1471-2253-14-96] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 10/17/2014] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Historically, the elective ventilatory flow pattern for neonates has been decelerating flow (DF). Decelerating flow waveform has been suggested to improve gas exchange in the neonate when compared with square flow (SF) waveform by improving the ventilation perfusion. However, the superiority of DF compared with SF has not yet been demonstrated during ventilation in small infants. The aim of this study was to compare SF vs. DF, with or without end-inspiratory pause (EIP), in terms of oxygenation and ventilation in an experimental model of newborn piglets. METHODS The lungs of 12 newborn Landrace/LargeWhite crossbred piglets were ventilated with SF, DF, SF-EIP and DF-EIP. Tidal volume (VT), inspiratory to expiratory ratio (I/E), respiratory rate (RR), and FiO2 were keep constant during the study. In order to assure an open lung during the study while preventing alveolar collapse, a positive end-expiratory pressure (PEEP) of 6 cmH2O was applied after a single recruitment maneuver. Gas exchange, lung mechanics and hemodynamics were measured. RESULTS The inspiratory flow waveform had no effect on arterial oxygenation pressure (PaO2) (276 vs. 278 mmHg, p = 0.77), alveolar dead space to alveolar tidal volume (VDalv/VTalv) (0.21 vs. 0.19 ml, p = 0.33), mean airway pressure (Pawm) (13.1 vs. 14.0 cmH2O, p = 0.69) and compliance (Crs) (3.5 vs. 3.5 ml cmH2O(-1), p = 0.73) when comparing SF and DF. A short EIP (10%) did not produce changes in the results. CONCLUSION The present study showed that there are no differences between SF, DF, SF-EIP and DF-EIP in oxygenation, ventilation, lung mechanics, or hemodynamics in this experimental model of newborn piglets with healthy lungs.
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Affiliation(s)
- Carlos Ferrando
- Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain
| | - Marisa García
- Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain
| | - Andrea Gutierrez
- Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain
| | - Jose A Carbonell
- Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain
| | - Gerardo Aguilar
- Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain
| | - Marina Soro
- Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain
| | - Francisco J Belda
- Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain
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Dembinski R, Bensberg R, Marx G, Rossaint R, Quintel M, Vohmann C, Kuhlen R. Semi-fluorinated alkanes as carriers for drug targeting in acute respiratory failure. Exp Lung Res 2011; 36:499-507. [PMID: 20939753 DOI: 10.3109/01902141003721457] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Partial liquid ventilation (PLV) with perfluorocarbons may cause pulmonary recruitment in acute lung injury (ALI). Semi-fluorinated alkanes (SFAs) provide biochemical properties similar to perfluorocarbons. Additionally, SFAs are characterized by increased lipophilicity. Therefore, SFA-PLV may be considered for deposition of certain therapeutic drugs into atelectatic lung areas. In this experimental study SFA-PLV was evaluated to demonstrate feasibility, pulmonary recruitment, and efficacy of drug deposition. Feasibility of SFA-PLV was determined in pigs with and without experimental ALI. Animals were randomized to PLV with SFAs up to a cumulative amount of 30 mL x kg⁻¹ or to conventional mechanical ventilation. Pulmonary recruitment effects were determined by analyzing ventilation-perfusion distributions. Efficacy of intrapulmonary drug deposition was evaluated in further experiments by measuring drug serum concentrations in the course of PLV with SFA-dissolved α-tocopherol and ibuprofen. Increasing SFA doses caused progressive reduction of intrapulmonary shunt in animals with ALI, indicating pulmonary recruitment. PLV with SFA-dissolved α-tocopherol had no effect on serum levels of α-tocopherol, whereas PLV with SFA-dissolved ibuprofen caused a rapid increase of serum levels of ibuprofen. The authors conclude that SFA-PLV is feasible and causes pulmonary recruitment in ALI. Effectiveness of drug deposition in the lung obviously depends on the partitioning drugs out of the SFA phase into blood.
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Affiliation(s)
- Rolf Dembinski
- Department of Intensive Care Medicine, RWTH University Hospital Aachen, Germany.
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Dembinski R, Hochhausen N, Terbeck S, Bickenbach J, Stadermann F, Rossaint R, Kuhlen R. Effectiveness of nitric oxide during spontaneous breathing in experimental lung injury. Exp Lung Res 2010; 36:159-66. [DOI: 10.3109/01902140903225416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Duenges B, Vogt A, Bodenstein M, Wang H, Böhme S, Röhrig B, Baumgardner JE, Markstaller K. A comparison of micropore membrane inlet mass spectrometry-derived pulmonary shunt measurement with Riley shunt in a porcine model. Anesth Analg 2009; 109:1831-5. [PMID: 19923510 DOI: 10.1213/ane.0b013e3181bbc401] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The multiple inert gas elimination technique was developed to measure shunt and the ratio of alveolar ventilation to simultaneous alveolar capillary blood flow in any part of the lung (V(A)'/Q') distributions. Micropore membrane inlet mass spectrometry (MMIMS), instead of gas chromatography, has been introduced for inert gas measurement and shunt determination in a rabbit lung model. However, agreement with a frequently used and accepted method for quantifying deficits in arterial oxygenation has not been established. We compared MMIMS-derived shunt (M-S) as a fraction of total cardiac output (CO) with Riley shunt (R-S) derived from the R-S formula in a porcine lung injury model. METHODS To allow a broad variance of atelectasis and therefore shunt fraction, 8 sham animals did not receive lavage, and 8 animals were treated by lung lavages with 30 mL/kg warmed lactated Ringer's solution as follows: 2 animals were lavaged once, 5 animals twice, and 1 animal 3 times. Variables were recorded at baseline and twice after induction of lung injury (T1 and T2). Retention data of sulfur hexafluoride, krypton, desflurane, enflurane, diethyl ether, and acetone were analyzed by MMIMS, and M-S was derived using a known algorithm for the multiple inert gas elimination technique. Standard formulas were used for the calculation of R-S. RESULTS Forty-four pairs of M-S and R-S were recorded. M-S ranged from 0.1% to 35.4% and R-S from 3.7% to 62.1%. M-S showed a correlation with R-S described by linear regression: M-S = -4.26 + 0.59 x R-S (r(2) = 0.83). M-S was on average lower than R-S (mean = -15.0% CO, sd = 6.5% CO, and median = -15.1), with lower and upper limits of agreement of -28.0% and -2.0%, respectively. The lower and upper limits of the 95% confidence intervals were -17.0 and -13.1 (P < 0.001, Student's t-test). CONCLUSIONS Shunt derived from MMIMS inert gas retention data correlated well with R-S during breathing of oxygen. Shunt as derived by MMIMS was generally less than R-S.
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Affiliation(s)
- Bastian Duenges
- Department of Anesthesiology, Johannes Gutenberg- University, Mainz, Germany
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Henzler D, Hochhausen N, Dembinski R, Orfao S, Rossaint R, Kuhlen R. Parameters derived from the pulmonary pressure volume curve, but not the pressure time curve, indicate recruitment in experimental lung injury. Anesth Analg 2007; 105:1072-8, table of contents. [PMID: 17898390 DOI: 10.1213/01.ane.0000278733.94863.09] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND In acute lung injury, ventilation avoiding tidal hyperinflation and tidal recruitment has been proposed to prevent ventilator-associated lung injury. Information about dynamic recruitment may be obtained from the characteristics of pressure-volume (PV) curves or the profile of pressure-time (Paw-t) curves. METHODS Six anesthetized pigs with lung lavage-induced acute lung injury were ventilated with lung-protective settings. We measured the effects of a standard recruitment maneuver on hysteresis area and ratio obtained from the PV curve and on the stress index obtained from the Paw-t curve and correlated this with aerated and nonaerated lung volumes as measured by multislice computed tomography. RESULTS Hysteresis area and ratio correlated with aerated lung volume (r = 0.886). The recruitment maneuver resulted in an increase in aerated (+12%) and a decrease (-18%) in nonaerated lung. Hysteresis area correlated with alveolar recruitment, represented by an increase in aerated lung (r = 0.886) and a decrease in nonaerated lung (r = -0.829) during tidal ventilation. The stress index was always >1 and indicated tidal hyperinflation only. Values did not change after the recruitment maneuver and did not correlate with any other lung volume. CONCLUSIONS Parameters derived from the PV curve may help in characterizing the lung aeration of the lung and in indicating recruitment. In the presence of lung-protective ventilator settings, the stress index derived from the Paw-t curve was not able to indicate recruitment.
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Affiliation(s)
- Dietrich Henzler
- Department of Anesthesiology, University Hospital, RWTH Aachen, Aachen, Germany.
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Pumpless extracorporeal lung assist for protective mechanical ventilation in experimental lung injury*. Crit Care Med 2007; 35:2359-66. [DOI: 10.1097/01.ccm.0000281857.87354.a5] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Unzueta MC, Casas JI, Moral MV. Pressure-controlled versus volume-controlled ventilation during one-lung ventilation for thoracic surgery. Anesth Analg 2007; 104:1029-33, tables of contents. [PMID: 17456648 DOI: 10.1213/01.ane.0000260313.63893.2f] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Pressure-controlled ventilation (PCV) has been suggested as a tool to improve oxygenation during one-lung ventilation (OLV) for patients undergoing thoracic surgery. In this study we investigated whether PCV results in improved arterial oxygenation compared with volume-controlled ventilation (VCV) during OLV. METHODS Fifty-eight patients with good preoperative pulmonary function scheduled for thoracic surgery were prospectively randomized into two groups. Those in group A underwent OLV initially with VCV for 30 min followed by PCV for a similar period of time. Those in group B underwent OLV initially with PCV for 30 min followed by VCV for a similar duration. Airway pressures and arterial blood gases were obtained during OLV at the end of each ventilatory mode. RESULTS There were no differences during OLV in arterial oxygenation between VCV (Pao2, 206.1 +/- 62.4 mm Hg) and PCV (Pao2, 202.1 +/- 56.4 mm Hg; P = 0.534). Peak airway pressure was lower with PCV than with VCV (24.43 +/- 3.42 cm H2O vs. 34.16 +/- 5.21 cm H2O; P < 0.001). CONCLUSIONS The use of PCV during OLV does not lead to improved oxygenation during OLV compared with VCV for patients with good preoperative pulmonary function, but PCV did lead to lower peak airway pressures. Further study is needed for patients with severe obstructive or restrictive pulmonary disease.
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Affiliation(s)
- M Carmen Unzueta
- Department of Anesthesiology, Hospital de Sant Pau, Barcelona, Spain.
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Abstract
As mechanical ventilators become increasingly sophisticated, clinicians are faced with a variety of ventilatory modes that use volume, pressure, and time in combination to achieve the overall goal of assisted ventilation. Although much has been written about the advantages and disadvantages of these increasingly complex modalities, currently there is no convincing evidence of the superiority of one mode of ventilation over another. Pressure control ventilation may offer particular advantages in certain circumstances in which variable flow rates are preferred or when pressure and volume limitation is required. The goal of this article is to provide clinicians with a fundamental understanding of the dependent and independent variables active in pressure control ventilation and describe features of the mode that may contribute to improved gas exchange and patient-ventilator synchronization.
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Affiliation(s)
- Dane Nichols
- Division of Pulmonary & Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Mailcode UHN-67, Portland, OR 97239, USA.
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Fujita Y, Maeda Y, Fujino Y, Uchiyama A, Mashimo T, Nishimura M. Effect of peak inspiratory flow on gas exchange, pulmonary mechanics, and lung histology in rabbits with injured lungs. J Anesth 2006; 20:96-101. [PMID: 16633765 DOI: 10.1007/s00540-005-0374-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Accepted: 12/01/2005] [Indexed: 11/25/2022]
Abstract
PURPOSE The aim of this study was to evaluate, using a rabbit model, the little-known effect of different levels of peak inspiratory flow on acutely injured lungs. METHODS Fourteen male rabbits (body weight, 2,711 +/- 146 g) were anesthetized and their lungs were injured by alveolar overstretch with mechanical ventilation until Pa(O(2)) was reduced below 300 mmHg. Injured animals were randomly assigned to: the P group-to receive pressure-regulated volume-control ventilation (PRVCV; n = 7); and the V group-to receive volume-control ventilation (VCV; n = 7). Other ventilator settings were: fraction of inspired oxygen (FI(O(2)), 1.0; tidal volume, 20 ml x kg(-1); positive end-expiratory pressure (PEEP) 5 cmH(2)O; and respiratory rate, 20 min(-1). The animals were thus ventilated for 4 h. Throughout the protocol, ventilatory parameters and blood gas were measured every 30 min. After the protocol, the lung wet-to-dry ratio and histological lung injury score were evaluated in the excised lungs. RESULTS Throughout the protocol, peak inspiratory flow and mean inspiratory flow values in the P group were significantly higher than those in the V group (26.7 +/- 5.0 l x min(-1) vs 1.2 +/- 0.2 l x min(-1), and 4.3 +/- 0.3 l x min(-1) vs 1.1 +/- 0.1 l x min(-1); P < 0.05). The wet-to-dry ratio in the P group was also significantly higher than that in the V group (7.7 +/- 0.9 vs 6.3 +/- 0.5; P < 0.05). More animals in the P group than in the V group had end-of-protocol Pa(O(2))/FI(O(2)) ratios below 200 mmHg (43% vs 0%; P = 0.06). CONCLUSION In rabbits with injured lungs, high peak inspiratory flow with high tidal volume (V(T)) reduces the Pa(O(2))/FI(O(2)) ratio and increases the lung wet-to-dry ratio.
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Affiliation(s)
- Yasuki Fujita
- Intensive Care Unit, Osaka University Hospital, 2-15 Yamadaoka, Suita 565-0871, Japan
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Gattinoni L, Caironi P, Carlesso E. How to ventilate patients with acute lung injury and acute respiratory distress syndrome. Curr Opin Crit Care 2005; 11:69-76. [PMID: 15659948 DOI: 10.1097/00075198-200502000-00011] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW The purpose of this paper is to review the mechanisms of ventilator-induced lung injury as a basis for providing the less damaging mechanical ventilation in patients with acute respiratory failure. RECENT FINDINGS In normal lungs, high tidal volume causes an immediate gene upregulation and downregulation. Although the importance of alveolar inflammatory reaction is well known, recent findings suggest the potential role of airway distension in causing ventilator-induced lung injury. The initial activation has been shown to occur in the airways, accounting for the damages induced by high peak flow. The healthier lung regions are more exposed to the injury, since they may be subjected to strain. Challenge with endotoxin enhances in a synergistic manner the pulmonary inflammation induced by mechanical ventilation. However, mechanical strain and endotoxin seem to trigger lung inflammation through two different pathways. Despite convincing experimental and clinical evidences of lung injury, the clinical implementation of low tidal volume ventilation is still limited and has not yet become part of standard clinical practice. Setting positive end-expiratory pressure remains an open problem because the ALVEOLI study did not provide any exhaustive answers, likely because of methodologic problems and, unphysiologic design. SUMMARY Gentle lung ventilation must be standard practice. Because stress and strain are the triggers of ventilator-induced lung injury, their clinical equivalents should be measured (transpulmonary pressure and the ratio between tidal volume and end-expiratory lung volume). For a rational application of positive end-expiratory pressure, the potential for recruitment in any single patient should be estimated.
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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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Roth H, Luecke T, Deventer B, Joachim A, Herrmann P, Quintel M. Pulmonary gas distribution during ventilation with different inspiratory flow patterns in experimental lung injury -- a computed tomography study. Acta Anaesthesiol Scand 2004; 48:851-61. [PMID: 15242429 DOI: 10.1111/j.1399-6576.2004.00430.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND There is still controversy about the optimal inspiratory flow pattern for ventilation of patients with acute lung injury. The aim of this study was to compare the effects of pressure-controlled ventilation (PCV) with a decelerating inspiratory flow with volume-controlled ventilation (VCV) with constant inspiratory flow on pulmonary gas distribution (PGD) in experimentally induced ARDS. METHODS Sixteen adult sheep were randomized to be ventilated with PCV or VCV after surfactant depletion by repeated bronchoalveolar lavage. Positive end-expiratory pressure (PEEP) was increased in a stepwise manner from zero end-expiratory pressure (ZEEP) to 7, 14 and 21 cm H(2)O in hourly intervals. Respiratory rate, inspiration-to-expiration ratio and tidal volume were kept constant. Central hemodynamics, gas exchange and airway pressures were measured. Electron beam computed tomographic (EBCT) scans of the entire lungs were performed at baseline (preinjury) and each level of end-expiratory pressure during an inspiratory and expiratory hold maneuver. The lungs were three-dimensionally reconstructed and volumetric assessments were made separating the lungs into four subvolumes classified as overinflated, normally aerated, poorly aerated and nonaerated. RESULTS Pressure-controlled ventilation led to a decrease in peak airway pressure and an increase in mean airway pressure. No differences between groups were found regarding plateau pressures, hemodynamics and gas exchange. Recruitment, defined as a decrease in expiratory lung volume classified as nonaerated, was similar in both groups and predominantly associated with PEEP. Overinflated lung volumes were increased with PCV. CONCLUSIONS In this model of acute lung injury, ventilation with decelerating inspiratory flow had no beneficial effects on PGD when compared with ventilation with constant inspiratory flow, while the increase in overinflated lung volumes may raise concerns regarding potential ventilator-associated lung injury.
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Affiliation(s)
- H Roth
- Department of Anesthesiology and Critical Care, University Hospital of Mannheim, Faculty of Clinical Medicine, University of Heidelberg, Heidelberg, Germany
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Abstract
Mechanical ventilation is the second most frequently performed therapeutic intervention after treatment for cardiac arrhythmias in intensive care units today. Countless lives have been saved with its use despite being associated with a greater than 30% in-hospital mortality rate. As life expectancies increase and people with chronic illnesses survive longer, artificial support with mechanical ventilation is also expected to rise. In one survey, over half of senior internal medicine residents reported their training on mechanical ventilation as inadequate, whereas the majority of critical care nurses reported having received no formal education on its use. Technological advances resulting in the availability of sleeker ventilators with graphic waveform displays and new modes of ventilation have challenged the bedside clinicians to incorporate this new data along with evidenced-based research into their daily practice. A review of current thoughts on mechanical ventilation and weaning is presented.
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Affiliation(s)
- Denise Fenstermacher
- Medical Intensive Care Unit, University of Illinois Medical Center at Chicago, Chicago, IL 60612, USA.
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