1
|
Cruces P, Moreno D, Reveco S, Ramirez Y, Díaz F. Plateau Pressure and Driving Pressure in Volume- and Pressure-Controlled Ventilation: Comparison of Frictional and Viscoelastic Resistive Components in Pediatric Acute Respiratory Distress Syndrome. Pediatr Crit Care Med 2023; 24:750-759. [PMID: 37260322 DOI: 10.1097/pcc.0000000000003291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
OBJECTIVES To examine frictional, viscoelastic, and elastic resistive components, as well threshold pressures, during volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) in pediatric patients with acute respiratory distress syndrome (ARDS). DESIGN Prospective cohort study. SETTING Seven-bed PICU, Hospital El Carmen de Maipú, Chile. PATIENTS Eighteen mechanically ventilated patients less than or equal to 15 years old undergoing neuromuscular blockade as part of management for ARDS. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS All patients were in VCV mode during measurement of pulmonary mechanics, including: the first pressure drop (P1) upon reaching zero flow during the inspiratory hold, peak inspiratory pressure (PIP), plateau pressure (P PLAT ), and total positive end-expiratory pressure (tPEEP). We calculated the components of the working pressure, as defined by the following: frictional resistive = PIP-P1; viscoelastic resistive = P1-P PLAT ; purely elastic = driving pressure (ΔP) = P PLAT -tPEEP; and threshold = intrinsic PEEP. The procedures and calculations were repeated on PCV, keeping the same tidal volume and inspiratory time. Measurements in VCV were considered the gold standard. We performed Spearman correlation and Bland-Altman analysis. The median (interquartile range [IQR]) for patient age was 5 months (2-17 mo). Tidal volume was 5.7 mL/kg (5.3-6.1 mL/kg), PIP cm H 2 O 26 (23-27 cm H 2 O), P1 23 cm H 2 O (21-26 cm H 2 O), P PLAT 19 cm H 2 O (17-22 cm H 2 O), tPEEP 9 cm H 2 O (8-9 cm H 2 O), and ΔP 11 cm H 2 O (9-13 cm H 2 O) in VCV mode at baseline. There was a robust correlation (rho > 0.8) and agreement between frictional resistive, elastic, and threshold components of working pressure in both modes but not for the viscoelastic resistive component. The purely frictional resistive component was negligible. Median peak inspiratory flow with decelerating-flow was 21 (IQR, 15-26) and squared-shaped flow was 7 L/min (IQR, 6-10 L/min) ( p < 0.001). CONCLUSIONS P PLAT , ΔP, and tPEEP can guide clinical decisions independent of the ventilatory mode. The modest purely frictional resistive component emphasizes the relevance of maintaining the same safety limits, regardless of the selected ventilatory mode. Therefore, peak inspiratory flow should be studied as a mechanism of ventilator-induced lung injury in pediatric ARDS.
Collapse
Affiliation(s)
- Pablo Cruces
- Departamento de Pediatría, Unidad de Paciente Crítico Pediátrico, Hospital El Carmen de Maipú, Santiago, Chile
- Centro de Investigación de Medicina Veterinaria, Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
- Red Colaborativa Pediátrica de Latinoamérica (LARed Network), Montevideo, Uruguay
- Unidad de Investigación y Epidemiología Clínica, Escuela de Medicina, Universidad Finis Terrae, Santiago, Chile
| | - Diego Moreno
- Departamento de Pediatría, Unidad de Paciente Crítico Pediátrico, Hospital El Carmen de Maipú, Santiago, Chile
| | - Sonia Reveco
- Departamento de Pediatría, Unidad de Paciente Crítico Pediátrico, Hospital El Carmen de Maipú, Santiago, Chile
| | - Yenny Ramirez
- Departamento de Pediatría, Unidad de Paciente Crítico Pediátrico, Hospital El Carmen de Maipú, Santiago, Chile
| | - Franco Díaz
- Departamento de Pediatría, Unidad de Paciente Crítico Pediátrico, Hospital El Carmen de Maipú, Santiago, Chile
- Red Colaborativa Pediátrica de Latinoamérica (LARed Network), Montevideo, Uruguay
- Unidad de Investigación y Epidemiología Clínica, Escuela de Medicina, Universidad Finis Terrae, Santiago, Chile
| |
Collapse
|
2
|
Chiumello D, Meli A, Pozzi T, Lucenteforte M, Simili P, Sterchele E, Coppola S. Different Inspiratory Flow Waveform during Volume-Controlled Ventilation in ARDS Patients. J Clin Med 2021; 10:jcm10204756. [PMID: 34682881 PMCID: PMC8540057 DOI: 10.3390/jcm10204756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/30/2021] [Accepted: 10/12/2021] [Indexed: 11/16/2022] Open
Abstract
The most used types of mechanical ventilation are volume- and pressure-controlled ventilation, respectively characterized by a square and a decelerating flow waveform. Nowadays, the clinical utility of different inspiratory flow waveforms remains unclear. The aim of this study was to assess the effects of four different inspiratory flow waveforms in ARDS patients. Twenty-eight ARDS patients (PaO2/FiO2 182 ± 40 and PEEP 11.3 ± 2.5 cmH2O) were ventilated in volume-controlled ventilation with four inspiratory flow waveforms: square (SQ), decelerating (DE), sinusoidal (SIN), and trunk descending (TDE). After 30 min in each condition, partitioned respiratory mechanics and gas exchange were collected. The inspiratory peak flow was higher in the DE waveform compared to the other three waveforms, and in SIN compared to the SQ and TDE waveforms, respectively. The mean inspiratory flow was higher in the DE and SIN waveforms compared with TDE and SQ. The inspiratory peak pressure was higher in the SIN and SQ compared to the TDE waveform. Partitioned elastance was similar in the four groups; mechanical power was lower in the TDE waveform, while PaCO2 in DE. No major effect on oxygenation was found. The explored flow waveforms did not provide relevant changes in oxygenation and respiratory mechanics.
Collapse
Affiliation(s)
- Davide Chiumello
- Department of Anesthesia and Intensive Care, ASST Santi Paolo e Carlo, San Paolo University Hospital, Via Di Rudini 9, 20142 Milan, Italy;
- Department of Health Sciences, University of Milan, 20142 Milan, Italy; (T.P.); (M.L.); (P.S.); (E.S.)
- Coordinated Research Center on Respiratory Failure, University of Milan, 20142 Milan, Italy
- Correspondence:
| | - Andrea Meli
- Department of Anesthesia, Intensive Care and Emergency, Fondazione IRCCS Ca’ Granda Hospital Maggiore Policlinico, Via F. Sforza 35, 20122 Milan, Italy;
| | - Tommaso Pozzi
- Department of Health Sciences, University of Milan, 20142 Milan, Italy; (T.P.); (M.L.); (P.S.); (E.S.)
| | - Manuela Lucenteforte
- Department of Health Sciences, University of Milan, 20142 Milan, Italy; (T.P.); (M.L.); (P.S.); (E.S.)
| | - Paolo Simili
- Department of Health Sciences, University of Milan, 20142 Milan, Italy; (T.P.); (M.L.); (P.S.); (E.S.)
| | - Elda Sterchele
- Department of Health Sciences, University of Milan, 20142 Milan, Italy; (T.P.); (M.L.); (P.S.); (E.S.)
| | - Silvia Coppola
- Department of Anesthesia and Intensive Care, ASST Santi Paolo e Carlo, San Paolo University Hospital, Via Di Rudini 9, 20142 Milan, Italy;
| |
Collapse
|
3
|
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.
Collapse
|
4
|
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]
|
5
|
Ferrando C, Belda FJ. The Effects of Flow Waveform on Oxygenation in Pediatric Patients. Anesth Analg 2015; 121:1111. [PMID: 26378708 DOI: 10.1213/ane.0000000000000821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Carlos Ferrando
- Anesthesiology and Critical Care Department, Hospital Clinico Universitario of Valencia, Valencia, Spain Anesthesiology and Critical Care Department, Hospital Clinico Universitario of Valencia, Valencia, Spain; and, Department of Surgery, University of Valencia, Valencia, Spain,
| | | |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Respiratory mechanics in COPD patients who failed non-invasive ventilation: Role of intrinsic PEEP. Respir Physiol Neurobiol 2012; 184:35-40. [DOI: 10.1016/j.resp.2012.07.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/26/2012] [Accepted: 07/13/2012] [Indexed: 11/23/2022]
|
8
|
Perchiazzi G, Rylander C, Vena A, Derosa S, Polieri D, Fiore T, Giuliani R, Hedenstierna G. Lung regional stress and strain as a function of posture and ventilatory mode. J Appl Physiol (1985) 2011; 110:1374-83. [DOI: 10.1152/japplphysiol.00439.2010] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During positive-pressure ventilation parenchymal deformation can be assessed as strain (volume increase above functional residual capacity) in response to stress (transpulmonary pressure). The aim of this study was to explore the relationship between stress and strain on the regional level using computed tomography in anesthetized healthy pigs in two postures and two patterns of breathing. Airway opening and esophageal pressures were used to calculate stress; change of gas content as assessed from computed tomography was used to calculate strain. Static stress-strain curves and dynamic strain-time curves were constructed, the latter during the inspiratory phase of volume and pressure-controlled ventilation, both in supine and prone position. The lung was divided into nondependent, intermediate, dependent, and central regions: their curves were modeled by exponential regression and examined for statistically significant differences. In all the examined regions, there were strong but different exponential relations between stress and strain. During mechanical ventilation, the end-inspiratory strain was higher in the dependent than in the nondependent regions. No differences between volume- and pressure-controlled ventilation were found. However, during volume control ventilation, prone positioning decreased the end-inspiratory strain of dependent regions and increased it in nondependent regions, resulting in reduced strain gradient. Strain is inhomogeneously distributed within the healthy lung. Prone positioning attenuates differences between dependent and nondependent regions. The regional effects of ventilatory mode and body positioning should be further explored in patients with acute lung injury.
Collapse
Affiliation(s)
- Gaetano Perchiazzi
- Emergency and Organ Transplant, Bari University, Bari, Italy
- Medical Sciences–Clinical Physiology, Uppsala University, Uppsala, Sweden
| | - Christian Rylander
- Anaesthesia and Intensive Care Medicine, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Antonio Vena
- Intensive Care Unit, SS Annunziata Hospital, Taranto, Italy; and
| | - Savino Derosa
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Debora Polieri
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Tommaso Fiore
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Rocco Giuliani
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Göran Hedenstierna
- Medical Sciences–Clinical Physiology, Uppsala University, Uppsala, Sweden
| |
Collapse
|
9
|
Antonaglia V, Lucangelo U, Ristagno G, Tantillo S, Ferluga M, Torelli L, Zin WA. Gas distribution in a two-compartment model during volume or pressure ventilation: role of elastic elements. Respir Physiol Neurobiol 2010; 171:225-31. [PMID: 20338267 DOI: 10.1016/j.resp.2010.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 03/12/2010] [Accepted: 03/16/2010] [Indexed: 11/18/2022]
Abstract
The results of the studies on pulmonary gas distribution during constant-flow controlled-volume inflation (VCV) and inspiratory constant pressure inflation (PCV) in experimental studies are conflicting. In a mathematical model, with the characteristics of two lung compartments including tissue viscoelastic properties, pulmonary gas distribution was tested by simulating PCV and VCV at same inflation volumes. The compartmental distributions of the tidal volume were compared during CMV and PCV in different configurations obtained by changing the elastic and viscoelastic properties in each compartment, but maintaining the same total values of respiratory mechanics measured in patients. In all instances PCV resulted in a slightly higher air-trapping than in VCV mode. Heterogeneous elastic properties diverted most of the tidal volume towards the less compromised compartment. However, both ventilatory modes provided similar compartmental gas distribution, but during VCV compartmental peak pressures were higher in the sicker compartment respect to PCV. The use of PCV could grant a less remarkable pressure variability able to reduce the potential ventilator-associated lung injury. Moreover, the parameters measured during an end-inspiratory pause could not pinpoint unique characteristics for each configuration.
Collapse
Affiliation(s)
- Vittorio Antonaglia
- Department of Anesthesia and Intensive Care, Laboratory of Respiratory Biomechanics, University of Trieste, Cattinara Hospital, Strada di Fiume 447, I-34139 Trieste, Italy.
| | | | | | | | | | | | | |
Collapse
|
10
|
Carvalho ARS, Jandre FC, Pino AV, Bozza FA, Salluh J, Rodrigues R, Ascoli FO, Giannella-Neto A. Positive end-expiratory pressure at minimal respiratory elastance represents the best compromise between mechanical stress and lung aeration in oleic acid induced lung injury. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2008; 11:R86. [PMID: 17688701 PMCID: PMC2206498 DOI: 10.1186/cc6093] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 04/03/2007] [Accepted: 08/09/2007] [Indexed: 11/10/2022]
Abstract
INTRODUCTION Protective ventilatory strategies have been applied to prevent ventilator-induced lung injury in patients with acute lung injury (ALI). However, adjustment of positive end-expiratory pressure (PEEP) to avoid alveolar de-recruitment and hyperinflation remains difficult. An alternative is to set the PEEP based on minimizing respiratory system elastance (Ers) by titrating PEEP. In the present study we evaluate the distribution of lung aeration (assessed using computed tomography scanning) and the behaviour of Ers in a porcine model of ALI, during a descending PEEP titration manoeuvre with a protective low tidal volume. METHODS PEEP titration (from 26 to 0 cmH2O, with a tidal volume of 6 to 7 ml/kg) was performed, following a recruitment manoeuvre. At each PEEP, helical computed tomography scans of juxta-diaphragmatic parts of the lower lobes were obtained during end-expiratory and end-inspiratory pauses in six piglets with ALI induced by oleic acid. The distribution of the lung compartments (hyperinflated, normally aerated, poorly aerated and non-aerated areas) was determined and the Ers was estimated on a breath-by-breath basis from the equation of motion of the respiratory system using the least-squares method. RESULTS Progressive reduction in PEEP from 26 cmH2O to the PEEP at which the minimum Ers was observed improved poorly aerated areas, with a proportional reduction in hyperinflated areas. Also, the distribution of normally aerated areas remained steady over this interval, with no changes in non-aerated areas. The PEEP at which minimal Ers occurred corresponded to the greatest amount of normally aerated areas, with lesser hyperinflated, and poorly and non-aerated areas. Levels of PEEP below that at which minimal Ers was observed increased poorly and non-aerated areas, with concomitant reductions in normally inflated and hyperinflated areas. CONCLUSION The PEEP at which minimal Ers occurred, obtained by descending PEEP titration with a protective low tidal volume, corresponded to the greatest amount of normally aerated areas, with lesser collapsed and hyperinflated areas. The institution of high levels of PEEP reduced poorly aerated areas but enlarged hyperinflated ones. Reduction in PEEP consistently enhanced poorly or non-aerated areas as well as tidal re-aeration. Hence, monitoring respiratory mechanics during a PEEP titration procedure may be a useful adjunct to optimize lung aeration.
Collapse
Affiliation(s)
- Alysson Roncally S Carvalho
- Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Av. Horácio Macedo, CT Bloco H-327, 2030, 21941-914, Rio de Janeiro, Brazil
| | - Frederico C Jandre
- Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Av. Horácio Macedo, CT Bloco H-327, 2030, 21941-914, Rio de Janeiro, Brazil
| | - Alexandre V Pino
- Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Av. Horácio Macedo, CT Bloco H-327, 2030, 21941-914, Rio de Janeiro, Brazil
| | - Fernando A Bozza
- Fundação Oswaldo Cruz, Instituto de Pesquisa Clinica Evandro Chagas e Laboratório de Imunofarmacologia, IOC, Av Brasil, 4365, Manguinhos, 21045-900 Rio de Janeiro, Brazil
| | - Jorge Salluh
- National Institute of Cancer-1, ICU, Praça Cruz Vermelha, 20230-130 Rio de Janeiro, Brazil
| | - Rosana Rodrigues
- Radiodiagnostic Service, Clementino Fraga Filho Hospital, Federal University of Rio de Janeiro, R Professor Rodolpho Paulo Rocco, 255, 21-941-913 Rio de Janeiro, Brazil
| | - Fabio O Ascoli
- Fundação Oswaldo Cruz, Instituto de Pesquisa Clinica Evandro Chagas e Laboratório de Imunofarmacologia, IOC, Av Brasil, 4365, Manguinhos, 21045-900 Rio de Janeiro, Brazil
| | | |
Collapse
|
11
|
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.
Collapse
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.
| | | |
Collapse
|
12
|
Luecke T, Herrmann P, Kraincuk P, Pelosi P. Computed tomography scan assessment of lung volume and recruitment during high-frequency oscillatory ventilation. Crit Care Med 2005; 33:S155-62. [PMID: 15753722 DOI: 10.1097/01.ccm.0000155916.47455.df] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE This review describes how computed tomography has increased our understanding of the pathophysiology of acute respiratory distress syndrome. It summarizes current knowledge about lung volume changes and alveolar recruitment during high-frequency oscillatory ventilation (HFOV) assessed by computed tomography (CT), outlines potential problems when comparing HFOV with conventional ventilation (CV) as a result of the different pressure-time profiles, and describes future research directions. DATA SOURCE CT allows accurate assessment of total lung volumes and differentiation between overinflated, normally aerated, poorly aerated, and nonaerated lung regions. It allows for classification of different patterns of consolidation and may be predictive for the potential for recruitment. DATA SUMMARY Experimental data suggest that HFOV at mean airway pressures (mPaw) set according to a static PV curve leads to effective lung recruitment but results in overall lung volumes that are considerably higher than those predicted from the PV relationship. In saline-lavaged sheep, similar changes in total lung volumes and subvolumes were observed during HFOV and CV. One single study specifically assessed lung volume recruitment during HFOV as compared with CV in eight patients with acute respiratory distress syndrome from pneumonia or sepsis. After 48 hrs on HFOV, total ventilated lung volume was significantly increased, whereas only a minor increase in overinflated lung volume was observed. These changes correlated with a significant improvement in gas exchange. CONCLUSION CT is a valuable tool to quantify recruitment and overinflation during HFOV. Additional studies are needed to better characterize the specific effects of HFOV on lung volume and morphology.
Collapse
Affiliation(s)
- Thomas Luecke
- Department of Anesthesiology, University Hospital of Mannheim, Faculty of Clinical Medicine Mannheim, University of Heidelberg, Germany
| | | | | | | |
Collapse
|