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Affiliation(s)
- L Gattinoni
- Department of Anesthesiology, Medical University of Göttingen, Robert Koch Straße 40, 37075, Göttingen, Germany. .,Department of Pulmonary and Critical Care Medicine, University of Minnesota and Regions Hospital, St. Paul, MN, USA.
| | - J J Marini
- Department of Anesthesiology, Medical University of Göttingen, Robert Koch Straße 40, 37075, Göttingen, Germany.,Department of Pulmonary and Critical Care Medicine, University of Minnesota and Regions Hospital, St. Paul, MN, USA
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Giosa L, Busana M, Pasticci I, Bonifazi M, Macrì MM, Romitti F, Vassalli F, Chiumello D, Quintel M, Marini JJ, Gattinoni L. Mechanical power at a glance: a simple surrogate for volume-controlled ventilation. Intensive Care Med Exp 2019; 7:61. [PMID: 31773328 PMCID: PMC6879677 DOI: 10.1186/s40635-019-0276-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 10/16/2019] [Indexed: 11/24/2022] Open
Abstract
Background Mechanical power is a summary variable including all the components which can possibly cause VILI (pressures, volume, flow, respiratory rate). Since the complexity of its mathematical computation is one of the major factors that delay its clinical use, we propose here a simple and easy to remember equation to estimate mechanical power under volume-controlled ventilation:
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\begin{document}$$ \mathrm{Mechanical}\ \mathrm{Power}=\frac{\mathrm{VE}\times \left(\mathrm{Peak}\ \mathrm{Pressure}+\mathrm{PEEP}+F/6\right)}{20} $$\end{document}Mechanical Power=VE×Peak Pressure+PEEP+F/620![]() where the mechanical power is expressed in Joules/minute, the minute ventilation (VE) in liters/minute, the inspiratory flow (F) in liters/minute, and peak pressure and positive end-expiratory pressure (PEEP) in centimeter of water. All the components of this equation are continuously displayed by any ventilator under volume-controlled ventilation without the need for clinician intervention. To test the accuracy of this new equation, we compared it with the reference formula of mechanical power that we proposed for volume-controlled ventilation in the past. The comparisons were made in a cohort of mechanically ventilated pigs (485 observations) and in a cohort of ICU patients (265 observations). Results Both in pigs and in ICU patients, the correlation between our equation and the reference one was close to the identity. Indeed, the R2 ranged from 0.97 to 0.99 and the Bland-Altman showed small biases (ranging from + 0.35 to − 0.53 J/min) and proportional errors (ranging from + 0.02 to − 0.05). Conclusions Our new equation of mechanical power for volume-controlled ventilation represents a simple and accurate alternative to the more complex ones available to date. This equation does not need any clinical intervention on the ventilator (such as an inspiratory hold) and could be easily implemented in the software of any ventilator in volume-controlled mode. This would allow the clinician to have an estimation of mechanical power at a simple glance and thus increase the clinical consciousness of this variable which is still far from being used at the bedside. Our equation carries the same limitations of all other formulas of mechanical power, the most important of which, as far as it concerns VILI prevention, are the lack of normalization and its application to the whole respiratory system (including the chest wall) and not only to the lung parenchyma.
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Affiliation(s)
- Lorenzo Giosa
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Mattia Busana
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Iacopo Pasticci
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Matteo Bonifazi
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Matteo Maria Macrì
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Federica Romitti
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Francesco Vassalli
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Davide Chiumello
- SC Anestesia e Rianimazione, Ospedale San Paolo - Polo Universitario, ASST Santi Paolo e Carlo, Milan, Italy.,Dipartimento di Scienze Biomediche per la Salute, Centro Ricerca Coordinato di Insufficienza Respiratoria, Università degli Studi di Milano, Milan, Italy
| | - Michael Quintel
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - J J Marini
- University of Minnesota and Regions Hospital, Minneapolis/St. Paul, MN, USA
| | - Luciano Gattinoni
- Departement of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany.
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Formenti P, Umbrello M, Graf J, Adams AB, Dries DJ, Marini JJ. Reliability of transpulmonary pressure-time curve profile to identify tidal recruitment/hyperinflation in experimental unilateral pleural effusion. J Clin Monit Comput 2016; 31:783-791. [PMID: 27438965 DOI: 10.1007/s10877-016-9908-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 07/14/2016] [Indexed: 10/21/2022]
Abstract
The stress index (SI) is a parameter that characterizes the shape of the airway pressure-time profile (P/t). It indicates the slope progression of the curve, reflecting both lung and chest wall properties. The presence of pleural effusion alters the mechanical properties of the respiratory system decreasing transpulmonary pressure (Ptp). We investigated whether the SI computed using Ptp tracing would provide reliable insight into tidal recruitment/overdistention during the tidal cycle in the presence of unilateral effusion. Unilateral pleural effusion was simulated in anesthetized, mechanically ventilated pigs. Respiratory system mechanics and thoracic computed tomography (CT) were studied to assess P/t curve shape and changes in global lung aeration. SI derived from airway pressure (Paw) was compared with that calculated by Ptp under the same conditions. These results were themselves compared with quantitative CT analysis as a gold standard for tidal recruitment/hyperinflation. Despite marked changes in tidal recruitment, mean values of SI computed either from Paw or Ptp were remarkably insensitive to variations of PEEP or condition. After the instillation of effusion, SI indicates a preponderant over-distension effect, not detected by CT. After the increment in PEEP level, the extent of CT-determined tidal recruitment suggest a huge recruitment effect of PEEP as reflected by lung compliance. Both SI in this case were unaffected. We showed that the ability of SI to predict tidal recruitment and overdistension was significantly reduced in a model of altered chest wall-lung relationship, even if the parameter was computed from the Ptp curve profile.
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Affiliation(s)
- P Formenti
- Pulmonary Research Laboratory, Regions Hospital, St Paul, MN, USA. .,Dipartimento di Anestesiologia e Terapia Intensiva, Azienda Opsedaliera San Paolo - Polo Universitario, Univeristà degli Studi di Milano, Via A. Di Rudinì, 8, 20142, Milan, Italy.
| | - M Umbrello
- Dipartimento di Anestesiologia e Terapia Intensiva, Azienda Opsedaliera San Paolo - Polo Universitario, Univeristà degli Studi di Milano, Via A. Di Rudinì, 8, 20142, Milan, Italy
| | - J Graf
- Pulmonary Research Laboratory, Regions Hospital, St Paul, MN, USA.,Departamento de Paciente Critico, Clinica Alemana de Santiago, Facultad de Medicina Clinica Alemana, Universidad del Desarrollo, Vitacura, Santiago, Chile
| | - A B Adams
- Pulmonary Research Laboratory, Regions Hospital, St Paul, MN, USA
| | - D J Dries
- Department of Surgical Services, HealthPartners Medical Group, University of Minnesota, Minneapolis/St. Paul, MN, USA
| | - J J Marini
- Pulmonary Research Laboratory, Regions Hospital, St Paul, MN, USA
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Vieillard-Baron A, Matthay M, Teboul JL, Bein T, Schultz M, Magder S, Marini JJ. Experts' opinion on management of hemodynamics in ARDS patients: focus on the effects of mechanical ventilation. Intensive Care Med 2016; 42:739-749. [PMID: 27038480 DOI: 10.1007/s00134-016-4326-3] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 03/11/2016] [Indexed: 02/06/2023]
Abstract
RATIONALE Acute respiratory distress syndrome (ARDS) is frequently associated with hemodynamic instability which appears as the main factor associated with mortality. Shock is driven by pulmonary hypertension, deleterious effects of mechanical ventilation (MV) on right ventricular (RV) function, and associated-sepsis. Hemodynamic effects of ventilation are due to changes in pleural pressure (Ppl) and changes in transpulmonary pressure (TP). TP affects RV afterload, whereas changes in Ppl affect venous return. Tidal forces and positive end-expiratory pressure (PEEP) increase pulmonary vascular resistance (PVR) in direct proportion to their effects on mean airway pressure (mPaw). The acutely injured lung has a reduced capacity to accommodate flowing blood and increases of blood flow accentuate fluid filtration. The dynamics of vascular pressure may contribute to ventilator-induced injury (VILI). In order to optimize perfusion, improve gas exchange, and minimize VILI risk, monitoring hemodynamics is important. RESULTS During passive ventilation pulse pressure variations are a predictor of fluid responsiveness when conditions to ensure its validity are observed, but may also reflect afterload effects of MV. Central venous pressure can be helpful to monitor the response of RV function to treatment. Echocardiography is suitable to visualize the RV and to detect acute cor pulmonale (ACP), which occurs in 20-25 % of cases. Inserting a pulmonary artery catheter may be useful to measure/calculate pulmonary artery pressure, pulmonary and systemic vascular resistance, and cardiac output. These last two indexes may be misleading, however, in cases of West zones 2 or 1 and tricuspid regurgitation associated with RV dilatation. Transpulmonary thermodilution may be useful to evaluate extravascular lung water and the pulmonary vascular permeability index. To ensure adequate intravascular volume is the first goal of hemodynamic support in patients with shock. The benefit and risk balance of fluid expansion has to be carefully evaluated since it may improve systemic perfusion but also may decrease ventilator-free days, increase pulmonary edema, and promote RV failure. ACP can be prevented or treated by applying RV protective MV (low driving pressure, limited hypercapnia, PEEP adapted to lung recruitability) and by prone positioning. In cases of shock that do not respond to intravascular fluid administration, norepinephrine infusion and vasodilators inhalation may improve RV function. Extracorporeal membrane oxygenation (ECMO) has the potential to be the cause of, as well as a remedy for, hemodynamic problems. Continuous thermodilution-based and pulse contour analysis-based cardiac output monitoring are not recommended in patients treated with ECMO, since the results are frequently inaccurate. Extracorporeal CO2 removal, which could have the capability to reduce hypercapnia/acidosis-induced ACP, cannot currently be recommended because of the lack of sufficient data.
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Affiliation(s)
- A Vieillard-Baron
- Intensive Care Unit, Section Thorax-Vascular Disease-Abdomen-Metabolism, Service de Réanimation, Assistance Publique-Hôpitaux de Paris, University Hospital Ambroise Paré, 9, avenue Charles de Gaulle, 92100, Boulogne-Billancourt, France. .,University of Versailles Saint-Quentin en Yvelines, Faculty of Medicine Paris Ile-de-France Ouest, 78280, Saint-Quentin en Yvelines, France. .,INSERM U-1018, CESP, Team 5 (EpReC, Renal and Cardiovascular Epidemiology), UVSQ, 94807, Villejuif, France.
| | - M Matthay
- Departments of Medicine and Anesthesia and the Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - J L Teboul
- Assistance Publique-Hôpitaux de Paris, Hôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, service de réanimation médicale, Le Kremlin-Bicêtre, France.,Université Paris-Sud, Faculté de médecine Paris-Sud, Inserm UMR S_999, Le Kremlin-Bicêtre, France
| | - T Bein
- Department of Anesthesia, Operative Intensive Care, University Hospital Regensburg, 93042, Regensburg, Germany
| | - M Schultz
- Laboratory of Experimental Intensive Care and Anesthesiology, Department of Intensive Care, Academic Medical Center, Amsterdam, The Netherlands
| | - S Magder
- Department of Critical Care, McGill University Health Centre (Glen Site Campus), Montreal, Canada
| | - J J Marini
- Departments of Pulmonary and Critical Care Medicine, University of Minnesota and Regions Hospital, Minneapolis/St. Paul, MN, USA
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Gattinoni L, Marini JJ. Prone positioning and neuromuscular blocking agents are part of standard care in severe ARDS patients: we are not sure. Intensive Care Med 2015; 41:2201-3. [PMID: 26399892 DOI: 10.1007/s00134-015-4040-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 08/23/2015] [Indexed: 10/23/2022]
Affiliation(s)
- L Gattinoni
- Dipartimento di Anestesia, Rianimazione ed Emergenza Urgenza, Fondazione IRCCS Ca' Granda-Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy. .,Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milan, Italy.
| | - J J Marini
- University of Minnesota, Minneapolis/St. Paul, Minnesota, USA
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Graf J, Formenti P, Marini JJ. Consequences of Pleural Effusions for Respiratory Mechanics in Ventilated Patients. Intensive Care Med 2010. [DOI: 10.1007/978-1-4419-5562-3_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Crooke PS, Kongkul K, Lenbury Y, Adams AB, Carter CS, Marini JJ, Hotchkiss JR. Mathematical models for pressure controlled ventilation of oleic acid-injured pigs. Math Med Biol 2005; 22:99-112. [PMID: 15716301 DOI: 10.1093/imammb/dqh023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
One-compartment, mathematical models for pressure controlled ventilation, incorporating volume dependent compliances, linear and nonlinear resistances, are constructed and compared with data obtained from healthy and (oleic acid) lung-injured pigs. Experimental data are used to find parameters in the mathematical models and were collected in two forms. Firstly, the P(e)-V curves for healthy and lung injured pigs were constructed; these data are used to compute compliance functions for each animal. Secondly, dynamic data from pressure controlled ventilation for a variety of applied pressures are used to estimate resistance parameters in the models. The models were then compared against the collected dynamic data. The best mathematical models are ones with compliance functions of the form C(V) = a + bV where a and b are constants obtained from the P(e)-V curves and the resistive pressures during inspiration change from a linear relation P(r) = RQ to a nonlinear relation P(r) = RQ(epsilon) where Q is the flow into the one-compartment lung and epsilon is a positive number. The form of the resistance terms in the mathematical models indicate the possible presence of gas-liquid foams in the experimental data.
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Affiliation(s)
- P S Crooke
- Biomathematics Study Group, Department of Mathematics, Vanderbilt University, Nashville, TN 37240, USA.
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Marini JJ. Microvasculature in ventilator-induced lung injury: target or cause? Minerva Anestesiol 2004; 70:167-73. [PMID: 15173691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Clinicians managing acute lung injury must reconcile the competing objectives of ensuring adequate oxygen delivery and minimizing the adverse effects of ventilatory support. Judging from our experimental work, microvascular stresses appear to be a potent cofactor in the development of pulmonary edema as well as in the expression of lung damage resulting from an injurious pattern of ventilation. When the lung is ventilated with high pressure, raising pre-capillary pressure or reducing post capillary pressure are both undesirable. Raising ventilation frequency may also have cost. Such observations imply that reducing the demands for blood flow and ventilation are important considerations in formulating a lung protective approach to mechanical ventilation of ARDS.
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Affiliation(s)
- J J Marini
- University of Minnesota, St Paul, MN 55101, USA
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Marini JJ. How to recruit the injured lung. Minerva Anestesiol 2003; 69:193-200. [PMID: 12766707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Alveolar recruitment represents a challenging issue in ALI/ARDS patients. Multiple techniques have been compared: intermittent sighs, sustained application of high pressure in single or multiple episodes, use of progressive higher PEEP and lower tidal volumes (VT), with a fixed upper limit, and increase of PEEP, without modifying VT. Encouraging results emerge also from the use of prone position, that allows a better distribution of transalveolar forces, thus reducing ventilator induced lung injury. Moreover the use of spontaneous breathing, such as Bi-PAP mode, enhances re-expansion of dorsal lung regions and intriguing, but still uncertain results derive from biological variability of ventilatory pattern. Finally, a pressure-volume (P-V) curve of respiratory system can be employed to set appropriate PEEP level, to prevent collapse of new recruited alveoli. To monitor alveolar recruitment we can use P-V curves, continuous intra-arterial gas analysis, electrical impedence tomography. It is worth noting that different recruiting techniques are characterised by different efficacy and adverse hemodynamic effects. In conclusion, The "Open lung" approach should not be applied to every patient; it should be reserved to restore lung volume if deterioration occurs, by means of adequate PEEP level and lowest acceptable FiO(2).
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Affiliation(s)
- J J Marini
- Professor of Medicine, University of Minnesota, Minneapolis, MN 55101, USA
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Han JN, Liu YP, Ma S, Zhu YJ, Sui SH, Chen XJ, Luo DM, Adams AB, Marini JJ. Effects of decreasing the frequency of ventilator circuit changes to every 7 days on the rate of ventilator-associated pneumonia in a Beijing hospital. Respir Care 2001; 46:891-6. [PMID: 11513760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
INTRODUCTION We investigated whether decreasing ventilator circuit changes from every 2 days to every 7 days would impact ventilator-associated pneumonia rates at our institution. METHODS All mechanically ventilated patients at Peking Union Medical College Hospital were studied over a 21 month period. From March 1998 to February 1999, ventilator circuits were changed every 2 days, and from June through December 1999, ventilator circuits were changed every 7 days. Nosocomial pneumonia was identified using the criteria of the Centers for Disease Control. RESULTS In the 2-day-change group, there were 2,277 ventilator-patient days and 38 patients developed pneumonia, resulting in a pneumonia rate of 16.7 cases per 1,000 ventilator days. The 7-day-change group accumulated 972 ventilator days and 8 patients contracted pneumonia, resulting in a pneumonia rate of 8.2 cases per 1,000 ventilator days. The pneumonia rate was significantly lower in the 7-day-change group (p = 0.007). To standardize for seasonal variability, we compared results from the same seasonal time frames (June to December 1998 for the 2-day-change group, and June to December 1999 for the 7-day-change group), and obtained similar findings: during those periods, pneumonia rates were 24.2 cases per 1,000 ventilator days for the 2-day-change group and 8.9 cases per 1,000 ventilator days for the 7-day-change group (p = 0.001). CONCLUSIONS A circuit change interval of 7 days had a lower risk of ventilator-associated pneumonia than a 2-day change interval. Therefore, ventilator circuits can be safely changed every 7 days in our setting.
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Affiliation(s)
- J N Han
- Respiratory Care Center, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
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Hotchkiss JR, Blanch L, Naveira A, Adams AB, Carter C, Olson DA, Leo PH, Marini JJ. Relative roles of vascular and airspace pressures in ventilator-induced lung injury. Crit Care Med 2001; 29:1593-8. [PMID: 11505134 DOI: 10.1097/00003246-200108000-00016] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To determine whether elevations in pulmonary vascular pressure induced by mechanical ventilation are more injurious than elevations of pulmonary vascular pressure of similar magnitude occurring in the absence of mechanical ventilation. DESIGN Prospective comparative laboratory investigation. SETTING University research laboratory. SUBJECTS Male New Zealand white rabbits. INTERVENTIONS Three groups of isolated, perfused rabbit lungs were exposed to cyclic elevation of pulmonary artery pressures arising from either intermittent positive pressure mechanical ventilation or from pulsatile perfusion of lungs held motionless by continuous positive airway pressure. Peak, mean, and nadir pulmonary artery pressures and mean airway pressure were matched between groups (35, 27.4 +/- 0.74, and 20.8 +/- 1.5 mm Hg, and 17.7 +/- 0.22 cm H2O, respectively). MEASUREMENTS AND MAIN RESULTS Lungs exposed to elevated pulmonary artery pressures attributable to intermittent positive pressure mechanical ventilation formed more edema (6.8 +/- 1.3 vs. 1.1 +/- 0.9 g/g of lung), displayed more perivascular (61 +/- 26 vs. 15 +/- 13 vessels) and alveolar hemorrhage (76 +/- 11% vs. 26 +/- 18% of alveoli), and underwent larger fractional declines in static compliance (88 +/- 4.4% vs. 48 +/- 25.1% decline) than lungs exposed to similar peak and mean pulmonary artery pressures in the absence of tidal positive pressure ventilation. CONCLUSIONS Isolated phasic elevations of pulmonary artery pressure may cause less damage than those occurring during intermittent positive pressure mechanical ventilation, suggesting that cyclic changes in perivascular pressure surrounding extra-alveolar vessels may be important in the genesis of ventilator-induced lung injury.
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Affiliation(s)
- J R Hotchkiss
- Department of Pulmonary and Critical Care Medicine, Regions Hospital, University of Minnesota, St. Paul, MN, USA
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Crotti S, Mascheroni D, Caironi P, Pelosi P, Ronzoni G, Mondino M, Marini JJ, Gattinoni L. Recruitment and derecruitment during acute respiratory failure: a clinical study. Am J Respir Crit Care Med 2001; 164:131-40. [PMID: 11435251 DOI: 10.1164/ajrccm.164.1.2007011] [Citation(s) in RCA: 362] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In a model of acute lung injury, we showed that positive end-expiratory pressure (PEEP) and tidal volume (VT) are interactive variables that determine the extent of lung recruitment, that recruitment occurs across the entire range of total lung capacity, and that superimposed pressure is a key determinant of lung collapse. Aiming to verify if the same rules apply in a clinical setting, we randomly ventilated five ALI/ARDS patients with 10, 15, 20, 30, 35, and 45 cm H2O plateau pressure and 5, 10, 15, and 20 cm H2O of PEEP. For each PEEP-VT condition, we obtained computed tomography at end inspiration and end expiration. We found that recruitment occurred along the entire volume-pressure curve, independent of lower and upper inflection points, and that estimated threshold opening pressures were normally distributed (mode = 20 cm H2O). Recruitment occurred progressively from nondependent to dependent lung regions. Overstretching was not associated with hyperinflation. Derecruitment did not parallel deflation, and estimated threshold closing pressures were normally distributed (mode = 5 cm H2O). End-inspiratory and end-expiratory collapse were correlated, suggesting a plateau-PEEP interaction. When superimposed gravitational pressure exceeded PEEP, end-expiratory collapse increased. We concluded that the rules governing recruitment and derecruitment equally apply in an oleic acid model and in human ALI/ARDS.
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Affiliation(s)
- S Crotti
- Istituto di Anestesia e Rianimazione, Università degli Studi di Milano, Ospedale Maggiore Policlinico-IRCCS, Milan, Italy
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Pelosi P, Goldner M, McKibben A, Adams A, Eccher G, Caironi P, Losappio S, Gattinoni L, Marini JJ. Recruitment and derecruitment during acute respiratory failure: an experimental study. Am J Respir Crit Care Med 2001; 164:122-30. [PMID: 11435250 DOI: 10.1164/ajrccm.164.1.2007010] [Citation(s) in RCA: 322] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We aimed to elucidate the relationships between pleural (Ppl), esophageal (Pes), and superimposed gravitational pressures in acute lung injury, and to understand the mechanisms of recruitment and derecruitment. In six dogs with oleic acid respiratory failure, we measured Pes and Ppl in the uppermost, middle, and most dependent lung regions. Each dog was studied at positive end-expiratory pressure (PEEP) of 5 and 15 cm H2O and three levels of tidal volume (VT; low, medium, and high). For each PEEP-VT combination, we obtained a computed tomographic (CT) scan at end-inspiration and end-expiration. The variations of Ppl and Pes pressures were correlated (r = 0.86 +/- 0.07, p < 0.0001), as was the vertical gradient of transpulmonary (PL) and superimposed pressure (r = 0.92, p < 0.0001). Recruitment proceeded continuously along the entire volume-pressure curve. Estimated threshold opening pressures were normally distributed (mode = 20 to 25 cm H2O). The amount of end-expiratory collapse at the same PEEP and PL was significantly lower when ventilation was performed at high VT. End-inspiratory and end-expiratory collapse were highly correlated (r = 0.86, p < 0.0001), suggesting that as more tissue is recruited at end-inspiration, more remains recruited at end-expiration. When superimposed pressure exceeded applied airway pressure (Paw), collapse significantly increased.
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Affiliation(s)
- P Pelosi
- Istituto di Anestesia e Rianimazione, Università degli Studi di Milano, Ospedale Maggiore Policlinico-IRCCS, Milan, Italy
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Adams AB, Cakar N, Marini JJ. Static and dynamic pressure-volume curves reflect different aspects of respiratory system mechanics in experimental acute respiratory distress syndrome. Respir Care 2001; 46:686-93. [PMID: 11455939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
INTRODUCTION A lower inflection point, an upper inflection (or deflection) point, and respiratory system compliance can be estimated from an inspiratory static pressure-volume (SPV) curve of the respiratory system. Such data are often used to guide selection of positive end-expiratory pressure (PEEP)/tidal volume combinations. Dynamic pressure-volume (DPV) curves obtained during tidal ventilation are effortlessly displayed on modern mechanical ventilator monitors and bear a theoretical but unproven relationship to the more labor-intensive SPV curves. OBJECTIVE Attempting to relate the SPV and DPV curves, we assessed both curves under a range of conditions in a canine oleic acid lung injury model. METHODS Five mongrel dogs were anesthetized, paralyzed, and monitored to assure a stable preparation. Acute lung injury was induced by infusing oleic acid. SPV curves were constructed by the super-syringe method. DPV curves were constructed for a range of PEEP and inspiratory constant flow settings while ventilating at a frequency of 15 breaths/min and tidal volume of 350 mL. Functional residual capacity at PEEP = 0 cm H2O was measured by helium dilution. The change in lung volume by PEEP at 8, 16, and 24 cm H2O was measured by respiratory inductance plethysmography. RESULTS The slope of the second portion of the DPV curve did not parallel the corresponding slope of the SPV curve. The mean lower inflection point of the SPV curve was 13.2 cm H2O, whereas the lower inflection point of the DPV curve was related to the prevailing flow and PEEP settings. The absolute lung volume during the DPV recordings exceeded (p < 0.05) that anticipated from the SPV curves by (values are mean +/- SEM) 267 +/- 86 mL, 425 +/- 129 mL, and 494 +/- 129 mL at end expiration for PEEP = 8, 16, and 24 cm H2O, respectively. CONCLUSIONS The contours of the SPV curve are not reflected by those of the DPV curve in this model of acute lung injury. Therefore, this study indicates that DPV curve should not be used to guide the selection of PEEP/tidal volume combinations. Furthermore, an increase in end-expiratory lung volume occurs during tidal ventilation that is not reflected by the classical SPV curve, suggesting a stable component of lung volume recruitment attributable to tidal ventilation, independent of PEEP.
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Affiliation(s)
- A B Adams
- Pulmonary Research Laboratory, Regions Hospital, St Paul, Minnesota 55101-2595, USA.
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Abstract
Acute noninvasive ventilation is generally applied via face mask, with modified pressure support used as the initial mode to assist ventilation. Although an adequate seal can usually be obtained, leaks frequently develop between the mask and the patient's face. This leakage presents a theoretical problem, since the inspiratory phase of pressure support terminates when flow falls to a predetermined fraction of peak inspiratory flow. To explore the issue of mask leakage and machine performance, we used a mathematical model to investigate the dynamic behavior of pressure-supported noninvasive ventilation, and confirmed the predicted behavior through use of a test lung. Our mathematical and laboratory analyses indicate that even when subject effort is unvarying, pressure-support ventilation applied in the presence of an inspiratory leak proximal to the airway opening can be accompanied by marked variations in duration of the inspiratory phase and in autoPEEP. The unstable behavior was observed in the simplest plausible mathematical models, and occurred at impedance values and ventilator settings that are clinically realistic.
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Affiliation(s)
- J R Hotchkiss
- Section of Pulmonary and Critical Care, Regions Hospital and University of Minnesota, St. Paul, Minnesota 55101, USA.
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Abstract
Despite recent advances in understanding, the management of acute respiratory distress syndrome (ARDS) remains a challenging clinical problem. Optimization of gas exchange and preventing the iatrogenic propagation of lung injury are cornerstones of its clinical management. A number of novel approaches and adjuncts to mechanical ventilation have been described over the past decade to help achieve these goals, and some have been widely implemented with varying degrees of success. This chapter will review the rationale and evidence supporting the use of such adjunctive strategies.
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Affiliation(s)
- J P Kress
- Department of Medicine, Section of Pulmonary and Critical Care, University of Chicago, Chicago, Illinois 60637, USA.
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Marini JJ, Amato MB. Lung recruitment during ARDS. Minerva Anestesiol 2000; 66:314-9. [PMID: 10965708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- J J Marini
- Department of Pulmonary and Critical Care Medicine, University of Minnesota-Regions Hospital, USA
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Kloot TE, Blanch L, Melynne Youngblood A, Weinert C, Adams AB, Marini JJ, Shapiro RS, Nahum A. Recruitment maneuvers in three experimental models of acute lung injury. Effect on lung volume and gas exchange. Am J Respir Crit Care Med 2000; 161:1485-94. [PMID: 10806143 DOI: 10.1164/ajrccm.161.5.9809014] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Recruitment maneuvers (RM), consisting of sustained inflations at high airway pressures, have been advocated as an adjunct to mechanical ventilation in acute respiratory distress syndrome (ARDS). We studied the effect of baseline ventilatory strategy and RM on end-expiratory lung volume (EELV) and oxygenation in 18 dogs, using three models of acute lung injury (ALI; n = 6 in each group): saline lavage (LAV), oleic acid injury (OAI), and intratracheal instillation of Escherichia coli (pneumonia; PNM). All three models exhibited similar degrees of lung injury. The PNM model was less responsive to positive end-expiratory pressure (PEEP) than was the LAV or OAI model. Only the LAV model showed an oxygenation response to increasing tidal volume (VT). After RM, there were transient increases in Pa(O(2)) and EELV when ventilating with PEEP = 10 cm H(2)O. At PEEP = 20 cm H(2)O the lungs were probably fully recruited, since the plateau airway pressures were relatively high ( approximately 45 cm H(2)O) and the oxygenation was similar to preinjury values, thus making the system unresponsive to RM. Sustained improvement in oxygenation after RM was seen in the LAV model when ventilating with PEEP = 10 cm H(2)O and VT = 15 ml/kg. Changes in EELV correlated with changes in Pa(O(2)) only in the OAI model with PEEP = 10 cm H(2)O. We conclude that responses to PEEP, VT, and RM differ among these models of ALI. RM may have a role in some patients with ARDS who are ventilated with low PEEP and low VT.
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Affiliation(s)
- T E Kloot
- Department of Pulmonary and Critical Care Medicine, University of Minnesota, Regions Hospital, St. Paul, Minnesota, USA
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Abstract
BACKGROUND We previously demonstrated a markedly dependent distribution of ventilator-induced lung injury in oleic acid-injured supine animals ventilated with large tidal volumes and positive end-expiratory pressure > or =10 cm H2O. Because pleural pressure distributes more uniformly in the prone position, we hypothesized that the extent of injury induced by purely mechanical forces applied to the lungs of normal animals might improve and that the distribution of injury might be altered with prone positioning. OBJECTIVE To compare the extent and distribution of histologic changes and edema resulting from identical patterns of high end-inspiratory/low end-expiratory airway pressures in both supine and prone normal dogs. DESIGN/SETTING We ventilated 10 normal dogs (5 prone, 5 supine) for 6 hrs with identical ventilatory patterns (a tidal volume that generated a peak transpulmonary pressure of 35 cm H2O when implemented in the supine position before randomization, positive end-expiratory pressure = 3 cm H2O). Ventilator-induced lung injury was assessed by gravimetric analysis and histologic grading. MEASUREMENTS AND MAIN RESULTS Wet weight/dry weight ratios (WW/DW) and histologic scores were greater in the supine than the prone group (8.8+/-2.8 vs. 6.1+/-0.7; p = .01 and 1.4+/-0.3 vs. 1+/-0.3; p = .037, respectively). In the supine group, WW/DW and histologic scores were significantly greater in dependent than nondependent regions (9.4+/-1.9 vs. 6.7+/-0.9; p = .01 and 2.0+/-0.4 vs. 0.9+/-0.4; p = .043, respectively). In the prone group, WW/DW also was greater in dependent regions (6.7+/-1.1 vs. 5.8+/-0.5; p = .054), but no significant differences were found in histologic scores between dependent and nondependent regions (p = .42). CONCLUSION In this model of lung injury induced solely by mechanical forces, the prone position resulted in a less severe and more homogeneous distribution of ventilator-induced lung injury. These results parallel those previously obtained in oleic acid-preinjured animals ventilated with higher positive end-expiratory pressure.
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Affiliation(s)
- A Broccard
- Department of Pulmonary and Critical Care Medicine, University of Minnesota, Regions Hospital, St. Paul, USA
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Janz TG, Madan R, Marini JJ, Summer WR, Meduri GU, Smith RM, Epler GR, Schnader J. Clinical conference on management dilemmas: progressive infiltrates and respiratory failure. Chest 2000; 117:562-72. [PMID: 10669704 DOI: 10.1378/chest.117.2.562] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- T G Janz
- Department of Medicine, Wright State University School of Medicine, and Department of Medicine, Dayton VA Medical Center, Dayton, OH 45428, USA
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Hotchkiss JR, Blanch L, Murias G, Adams AB, Olson DA, Wangensteen OD, Leo PH, Marini JJ. Effects of decreased respiratory frequency on ventilator-induced lung injury. Am J Respir Crit Care Med 2000; 161:463-8. [PMID: 10673186 DOI: 10.1164/ajrccm.161.2.9811008] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To determine if decreased respiratory frequency (ventilatory rate) improves indices of lung damage, 17 sets of isolated, perfused rabbit lungs were ventilated with a peak static airway pressure of 30 cm H(2)O. All lungs were randomized to one of three frequency/peak pulmonary artery pressure combinations: F20P35 (n = 6): ventilatory frequency, 20 breaths/min, and peak pulmonary artery pressure, 35 mm Hg; F3P35 (n = 6), ventilatory frequency, 3 breaths/min, and peak pulmonary artery pressure of 35 mm Hg; or F20P20 (n = 5), ventilatory frequency, 20 breaths/min, and peak pulmonary artery pressure, 20 mm Hg. Mean airway pressure and tidal volume were matched between groups. Mean pulmonary artery pressure and vascular flow were matched between groups F20P35 and F3P35. The F20P35 group showed at least a 4.5-fold greater mean weight gain and a 3-fold greater mean incidence of perivascular hemorrhage than did the comparison groups, all p </= 0.05. F20P35 lungs also displayed more alveolar hemorrhage than did F20P20 lungs (p </= 0.05). We conclude that decreasing respiratory frequency can improve these indices of lung damage, and that limitation of peak pulmonary artery pressure and flow may diminish lung damage for a given ventilatory pattern.
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Affiliation(s)
- J R Hotchkiss
- Servei de Medicina Intensiva, Hospital de Sabadell, Corporacio Hospitalaria del Parc Tauli, Sabadell, Spain
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Bottino N, Eccher G, Pelosi P, McKibben A, Adams A, Goldner M, Marini JJ, Gattinoni L. Influence of different PEEP levels and tidal volumes on the regional nonaerated tissue: experimental study. Crit Care 2000. [PMCID: PMC3333047 DOI: 10.1186/cc843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- N Bottino
- 1st. Anestesia e Rianimazione, Osp. Maggiore Policlinico-IRCCS, via F. Sforza, 35, 20122, Milano, Italy
| | - G Eccher
- 1st. Anestesia e Rianimazione, Osp. Maggiore Policlinico-IRCCS, via F. Sforza, 35, 20122, Milano, Italy
| | - P Pelosi
- Dip. Scienze Cliniche e Biologiche, Univ. dell'Insubria, Varese, Italy
| | - A McKibben
- University of Minnesota, St Paul, MN, USA
| | - A Adams
- University of Minnesota, St Paul, MN, USA
| | - M Goldner
- University of Minnesota, St Paul, MN, USA
| | - JJ Marini
- University of Minnesota, St Paul, MN, USA
| | - L Gattinoni
- 1st. Anestesia e Rianimazione, Osp. Maggiore Policlinico-IRCCS, via F. Sforza, 35, 20122, Milano, Italy
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Bottino N, Eccher G, Pelosi P, McKibben A, Adams A, Goldner M, Marini JJ, Gattinoni L. Relationship between superimposed pressure and pleural pressure gradient in an experimental model of ARDS. Crit Care 2000. [PMCID: PMC3333039 DOI: 10.1186/cc835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Broccard AF, Hotchkiss JR, Suzuki S, Olson D, Marini JJ. Effects of mean airway pressure and tidal excursion on lung injury induced by mechanical ventilation in an isolated perfused rabbit lung model. Crit Care Med 1999; 27:1533-41. [PMID: 10470761 DOI: 10.1097/00003246-199908000-00022] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To study the relative contributions of mean airway pressure (mPaw) and tidal excursion (V(T)) to ventilator-induced lung injury under constant perfusion conditions. DESIGN Prospective, randomized study. SETTING Experimental animal laboratory. SUBJECTS Fifteen sets of isolated rabbit lungs. INTERVENTIONS Rabbit lungs were perfused (constant flow, 500 mL/min; capillary pressure, 10 mm Hg) and randomized to be ventilated at identical peak transpulmonary pressure (pressure control ventilation [30 cm H2O and frequency of 20/min]) with three different ventilatory patterns that differed from each other by either mPaw or V(T): group A (low mPaw [13.4+/-0.2 cm H2O]/large V(T) [55+/-8 mL], n = 5); group B (high mPaw [21.2+/-0.2 cm H2O]/small V(T) [18+/-1 mL], n = 5); and group C (high mPaw [21.8+/-0.5 cm H2O]/large V(T) [53+/-5 mL], n = 5). MEASUREMENTS AND MAIN RESULTS Continuous weight gain (edema formation), change in ultrafiltration coefficient (deltaKf, vascular permeability index), and histology (lung hemorrhage) were examined. In group A, deltaKf (0.08+/-0.08 g/min/cm H2O/100 g) was less than in group B (0.28+/-0.19 g/min/cm H2O/100 g) or group C (0.41+/-0.29 g/min/cm H2O/100 g) (p = .05). Group A experienced significantly less hemorrhage (histologic score, 5.4+/-2.2) than groups B (10.3+/-2.1) and C (11.1+/-3.0) (p < .05). A similar trend was observed for weight gain. In contrast to tidal excursion, mPaw was found to be a significant factor for lung hemorrhage and increased Kf (two-way analysis of variance; p < .05). Weight gain (r2 = .54, p = .04) and lung hemorrhage (r2 = .65, p = .01) correlated with the mean pulmonary artery pressure changes that resulted from the implementation of the ventilatory strategies. The difference between the changes in mPaw and mean pulmonary artery pressure linearly predicted deltaKf (p = .005 and .05, respectively, r2 = 0.73). CONCLUSIONS Under these experimental conditions, mPaw contributes more than tidal excursion to lung hemorrhage and permeability alterations induced by mechanical ventilation.
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Affiliation(s)
- A F Broccard
- Division of Pulmonary and Critical Care Medicine, University of Minnesota, Minneapolis, USA.
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Marini JJ. A lung-protective approach to ventilating ARDS. Respir Care Clin N Am 1998; 4:633-63, viii. [PMID: 9881397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A convincing and internally consistent body of literature now suggests that the traditional high tidal volume, normoxic, normacapnic ventilation paradigm may retard healing of the acutely injured lung. A growing number of practitioners are now shifting first priority from optimizing gas exchange, oxygen delivery, or respiratory system compliance to ensuring adequate lung protection. This article reviews the basis for concern about traditional ventilatory support in ARDS and develops an approach based on current evidence and newer options for management.
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Affiliation(s)
- J J Marini
- Department of Medicine, University of Minnesota, USA.
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Crooke PS, Head JD, Marini JJ, Hotchkiss JR. Patient-ventilator interaction: a general model for nonpassive mechanical ventilation. IMA J Math Appl Med Biol 1998; 15:321-37. [PMID: 9951713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
A general mathematical model for the dynamic behaviour of a single-compartment respiratory system in response to an arbitrary applied inspiratory airway pressure and arbitrary respiratory muscle activity is investigated. The model is used to compute explicit expressions for ventilation and pressure variables of clinical interest for clinician-selected and impedance-determined inputs. The outcome variables include tidal volume, end-expiratory pressure, minute ventilation, mean alveolar pressure, average pleural pressure, as well as the work performed by the ventilator and the respiratory muscles. It is also demonstrated that under suitable conditions, there is a flow reversal that can occur during inspiration.
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Affiliation(s)
- P S Crooke
- Department of Mathematics, Vanderbilt University, Nashville, TN 37240, USA.
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Abstract
Noninvasive ventilation (NIV) is the provision of ventilatory support to a spontaneously breathing patient without endotracheal intubation. In this review, we detail concerns related to endotracheal intubation and summarize the physiologic effects and clinical application of NIV. We then address the use of NIV in 5 conditions of particular interest to the practitioner of emergency medicine: exacerbated chronic obstructive lung disease, severe asthma, patients who are not candidates for endotracheal intubation, pneumonia, and pulmonary edema.
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Affiliation(s)
- J R Hotchkiss
- Department of Pulmonary and Critical Care Medicine, Regions Hospital, St. Paul, MN, USA
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Affiliation(s)
- J J Marini
- Department of Pulmonary and Critical Care, St. Paul Ramsey Medical Center, MN 55101, USA.
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Broccard AF, Hotchkiss JR, Kuwayama N, Olson DA, Jamal S, Wangensteen DO, Marini JJ. Consequences of vascular flow on lung injury induced by mechanical ventilation. Am J Respir Crit Care Med 1998; 157:1935-42. [PMID: 9620930 DOI: 10.1164/ajrccm.157.6.9612006] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To investigate whether the magnitude of blood flow contributes to ventilator-induced lung injury, 14 sets of isolated rabbit lungs were randomized for perfusion at either 300 (Group A: n = 7) or 900 ml/ min (Group B: n = 7) while ventilated with 30 cm H2O peak static pressure. Control lungs (Group C: n = 7) were ventilated with lower peak static pressure (15 cm H2O) and perfused at 500 ml/min. Weight gain, changes in the ultrafiltration coefficient (DeltaKf) and lung static compliance (CL), and extent of hemorrhage (scored by histology) were compared. Group B had a larger decrease in CL (-13 +/- 11%) than Groups A (2 +/- 6%) and C (5 +/- 5%) (p < 0.05). Group B had more hemorrhage and gained more weight (16.2 +/- 9.5 g) than Groups A (8.7 +/- 3.4 g) and C (1.6 +/- 1.0 g) (p < 0.05 for each pairwise comparison between groups). Finally, Kf (g . min-1 . cm H2O-1 . 100 g-1) increased the most in Group B (DeltaKf = 0.26 +/- 0. 20 versus 0.17 +/- 0.10 in Group A and 0.05 +/- 0.04 in Group C; p < 0.05 for B versus C). We conclude that the intensity of lung perfusion contributes to ventilator- induced lung injury in this model.
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Affiliation(s)
- A F Broccard
- Division of Pulmonary and Critical Care Medicine, University of Minnesota, Minneapolis/St. Paul, MN, USA
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Artigas A, Bernard GR, Carlet J, Dreyfuss D, Gattinoni L, Hudson L, Lamy M, Marini JJ, Matthay MA, Pinsky MR, Spragg R, Suter PM. The American-European Consensus Conference on ARDS, part 2: Ventilatory, pharmacologic, supportive therapy, study design strategies, and issues related to recovery and remodeling. Acute respiratory distress syndrome. Am J Respir Crit Care Med 1998; 157:1332-47. [PMID: 9563759 DOI: 10.1164/ajrccm.157.4.ats2-98] [Citation(s) in RCA: 240] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last 10 years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathologic features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.
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Artigas A, Bernard GR, Carlet J, Dreyfuss D, Gattinoni L, Hudson L, Lamy M, Marini JJ, Matthay MA, Pinsky MR, Spragg R, Suter PM. The American-European Consensus Conference on ARDS, part 2. Ventilatory, pharmacologic, supportive therapy, study design strategies and issues related to recovery and remodeling. Intensive Care Med 1998; 24:378-98. [PMID: 9609420 DOI: 10.1007/s001340050585] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last ten years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathological features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.
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Nahum A, Hoyt J, Schmitz L, Moody J, Shapiro R, Marini JJ. Effect of mechanical ventilation strategy on dissemination of intratracheally instilled Escherichia coli in dogs. Crit Care Med 1997; 25:1733-43. [PMID: 9377891 DOI: 10.1097/00003246-199710000-00026] [Citation(s) in RCA: 186] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To test the effect of different mechanical ventilation strategies on dissemination of intratracheally instilled Escherichia coli in dogs and to determine the extent and distribution of lung damage. DESIGN Prospective, randomized study. SETTING Experimental animal laboratory. SUBJECTS Eighteen anesthetized and paralyzed dogs. INTERVENTIONS We studied the effect of three ventilatory strategies based on two variables: transpulmonary pressure and positive end-expiratory pressure (PEEP). Group 1 animals (n = 6) were ventilated with a PEEP of 3 cm H2O and a tidal volume of 15 mL/kg, which generated an end-inspiratory transpulmonary pressure of < or = 15 cm H2O. In group 2(n = 6), tidal volume was adjusted to generate a transpulmonary pressure of 35 cm H2O and PEEP was set to 3 cm H2O. In group 3(n = 6), tidal volume was also adjusted to yield a transpulmonary pressure of 35 cm H2O but PEEP was set to 10 cm H2O. In each group, we instilled approximately 10(8) colony-forming units of E. coli into the trachea of the dogs and ventilated them with the chosen tidal volume and PEEP for 6 hrs afterward. MEASUREMENTS AND MAIN RESULTS We measured the pressure-volume relationship (pressure-volume curve) of the respiratory system before and 6 hrs after bacterial instillation. We obtained blood cultures before and 0.5, 1,2,3,4,5, and 6 hrs after bacterial instillation. After 6 hrs, the lungs were removed for histologic (histologic score) and gravimetric (wet-to-dry weight ratio, WW/DW) analysis. During the experiment 0, 5, and 1 dogs developed positive blood cultures in groups 1, 2, and 3, respectively. The number of dogs that developed bacteremia in group 2 was significantly greater than in the other two groups (p < .05). In group 1, pressure-volume curves demonstrated a lower inflection point which was greater than the end-inspiratory transpulmonary pressure suggesting that low transpulmonary pressure/low PEEP strategy ventilated aerated regions without expanding atelectatic areas. In group 2, pressure-volume curves demonstrated both a lower inflection point and an upper deflection point which were spanned by the tidal volume, suggesting that high transpulmonary pressure/low PEEP strategy might have caused both overdistention and cyclic closure and reopening. In group 3, pressure-volume curves demonstrated only a upper deflection point which was less than the maximal alveolar tidal pressure. At the end of the experimental protocol, group 2 manifested the most lung injury as assessed by gravimetric and histologic indices of lung injury. WW/DW of group 2(13.1 +/- 1.0 (SD); p < .05) was greater than groups 1 and 3(7.5 +/- 1.2 and 8.6 +/- 1.0, respectively). Similarly, the overall weighted histologic injury score for group 2 (1.19 +/- 0.26; p < .02) was greater than for groups 1 and 3 (0.82 +/- 0.20 and 0.88 +/- 0.22, respectively). For groups 2 and 3, the overall weighted histologic injury scores of the dependent regions were greater than the nondependent regions (p < .004). CONCLUSIONS We conclude that the ventilatory strategy most likely to overdistend the lungs while allowing repetitive opening and closure of alveoli (group 2) facilitated bacterial translocation from the alveoli to the bloodstream and increased lung injury, as determined by histologic and gravimetric analysis. PEEP ameliorated these effects, despite lung overdistention, but increased histologic and gravimetric indices of lung injury in dependent as compared with the nondependent regions.
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Affiliation(s)
- A Nahum
- Department of Pulmonary and Critical Care Medicine, University of Minnesota, St. Paul-Ramsey Medical Center, USA
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Broccard AF, Shapiro RS, Schmitz LL, Ravenscraft SA, Marini JJ. Influence of prone position on the extent and distribution of lung injury in a high tidal volume oleic acid model of acute respiratory distress syndrome. Crit Care Med 1997; 25:16-27. [PMID: 8989171 DOI: 10.1097/00003246-199701000-00007] [Citation(s) in RCA: 152] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To evaluate the influence of body position on the extent and distribution of experimental lung damage in an oleic acid canine model of acute respiratory distress syndrome, using mechanical ventilation with high tidal volumes and positive end-expiratory pressure (PEEP). DESIGN Prospective, randomized study. SETTING Experimental animal laboratory. SUBJECTS Twelve anesthetized and paralyzed dogs. INTERVENTIONS Ninety minutes after lung injury was induced by injection of oleic acid, 12 animals were randomized to be ventilated for 4 hrs, in either the supine (supine group, n = 6) or prone (prone group, n = 6) positions, using the same ventilatory pattern (F10(2) 0.6, PEEP > or = 10 cm H2O, and a tidal volume that generated a peak transpulmonary pressure of 35 cm H2O when implemented in the supine position). Regardless of randomization to position, the tidal volumes, F10(2), and PEEP were kept constant and the pulmonary artery occlusion pressure was maintained between 4 and 6 mm Hg for the duration of the study. MEASUREMENTS AND MAIN RESULTS At the end of the protocol, the lungs were excised for gravimetric determination (wet/dry weight ratio) and histologic examination (histologic score). Changes over time in the static pressure-volume curve of the lungs (obtained in the supine position) were also used as end-point variables. At baseline, hemodynamic and respiratory variables did not differ between groups. Just before randomization to position (90 mins after oleic acid injection), both groups presented similar lung static pressure-volume curves. Pulmonary artery occlusion pressure (4.3 +/- 1.9 vs. 4.8 +/- 1.3 mm Hg [supine vs. prone group]), cardiac output (4.1 +/- 0.4 vs. 5.2 +/- 1.3 L/min [supine vs. prone group]), and venous admixture (36.7 +/- 20.7% vs. 28.3 +/- 19.4% [supine vs. prone group]) were also not significantly (p > .05) different when measured in the supine position. At the end of the experiment, lung gravimetric data in the two experimental groups were not statistically different, suggesting a similar extent of edema. Histologic abnormalities, however, were less in the prone group than in the supine group (p < .01), due primarily to marked differences in extent and severity in the dependent regions of the lungs. Static lung compliance improved over time in the prone group (34 +/- 9 to 46 +/- 19 mL/cm H2O)(p = .02), but not in the supine group (34 +/- 6 to 36 +/- 6 mL/cm H2O). CONCLUSIONS After oleic acid-induced lung injury, animals ventilated with high tidal volume and PEEP undergo less extensive histologic change in the prone position than in the supine position. The prone position alters the distribution of histologic abnormalities.
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Affiliation(s)
- A F Broccard
- Department of Pulmonary and Critical Care Medicine, University of Minnesota, St. Paul-Ramsey Medical Center 55191-2595, USA
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Hotchkiss JR, Crooke PS, Marini JJ. Theoretical interactions between ventilator settings and proximal deadspace ventilation during tracheal gas insufflation. Intensive Care Med 1996; 22:1112-9. [PMID: 8923080 DOI: 10.1007/bf01699238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To investigate the theoretical interactions between ventilator settings, tracheal gas insufflation (TGI), and alveolar ventilation. DESIGN We derived differential equations governing compartmental volume changes in a one-compartment model of TGI-assisted ventilation and equations governing gas dilution in the airway proximal to the TGI catheter and the additional CO2 clearing ventilation arising from this dilution. This additional ventilation was called proximal ventilation. Validation was conducted in a mechanical lung analog. Model predictions for proximal ventilation were then generated over wide ranges of frequency, duty cycle, and tidal volume. RESULTS Significant interactions were identified between ventilator settings and proximal ventilation. The persistence of end-expiratory flow from the lung decreased proximal dilution by fresh gas and thereby reduced TGI-aided proximal ventilation. Changes in end-expiratory lung flow resulting from alterations in ventilator settings were correlated inversely with proximal ventilation. CONCLUSIONS During TGI with constant catheter flow, ventilator settings that promote end-expiratory flow of gas from the lung diminish proximal ventilation. When frequency increases, the decrease in dilution efficiency of the individual breath is partially offset by the increase in cycle number, an effect which is magnified by any concomitant decrease in inspired tidal volume. Prolongation of the duty cycle tends to decrease proximal ventilation. Increases in expiratory resistance, including those arising from the external ventilator circuit or the endotracheal tube, also impair proximal ventilation.
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Affiliation(s)
- J R Hotchkiss
- University of Minnesota, St. Paul Ramsey Medical Center, St. Paul 55101, USA
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Abstract
With few modifications, a high tidal volume, normoxic, normocapnic ventilation paradigm developed as the standard approach to supporting most critically ill patients. Large tidal volumes, high end-tidal (plateau) alveolar pressures, and low levels of positive end-expiratory pressure are still common in many ICUs during ventilation of acute respiratory distress syndrome (ARDS). A body of scientific literature now suggests that this traditional approach may retard healing of the injured lung. A relatively small but growing number of practitioners are shifting their first priority from optimizing oxygen exchange, oxygen delivery, or respiratory system compliance to ensuring adequate lung protection. This article reviews the basis for concern about traditional ventilatory support in ARDS and develops an approach based on current evidence and newer options for management.
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Affiliation(s)
- J J Marini
- Department of Pulmonary and Critical Care Medicine, St. Paul-Ramsey Medical Center, Minnesota, USA
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Hoyt JD, Marini JJ, Nahum A. Effect of tracheal gas insufflation on demand valve triggering and total work during continuous positive airway pressure ventilation. Chest 1996; 110:775-83. [PMID: 8797426 DOI: 10.1378/chest.110.3.775] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Tracheal gas insufflation (TGI) improves CO2 clearance and may reduce work of breathing by lowering the required minute ventilation (VE). However, TGI might also impair the ability to trigger the ventilator, because to lower external circuit pressures, inspiratory effort must outstrip catheter flow rate (Vc) and overcome the dynamic hyperinflation caused by TGI. We studied these effects using a two-chamber lung model of the respiratory muscles (RM) and lungs (L). The RM-chamber was ventilated using a sinusoidal flow pattern with a tidal volume (VT) of 0.5 L at various peak inspiratory flow rates (Vpk) to simulate differences in effort intensity. The L-chamber was connected to a 60-L/min continuous flow circuit with a 10 cm H2O positive end-expiratory pressure valve and to 3 different ventilatory demand valve circuits, each set at continuous positive airway pressure (CPAP) of 10 cm H2O. We used continuous TGI at 0, 2.5, 5, 10, and 15 L/min. The work of triggering (W-trig) increased with increasing Vc and decreased with increasing Vpk. The L-ventilator failed to trigger when Vc was 15 L/min and Vpk was 20 L/min. At a fixed VE, the effect of TGI on total mechanical inspiratory work (W-tot) was relatively small and varied among the different CPAP systems used. We conclude that weak patients may fail to open the demand valve of the CPAP system during TGI at high catheter flow rates. The net effect of TGI on the effort made by ventilated patients would depend not only on the interactions between TGI and the ventilator, but also on the efficiency of TGI in decreasing dead-space and lowering the VE requirement.
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Affiliation(s)
- J D Hoyt
- University of Minnesota, Department of Pulmonary and Critical Care Medicine, St. Paul-Ramsey Medical Center, St. Paul, USA
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Nahum A, Ravenscraft SA, Adams AB, Marini JJ. Distal effects of tracheal gas insufflation: changes with catheter position and oleic acid lung injury. J Appl Physiol (1985) 1996; 81:1121-7. [PMID: 8889743 DOI: 10.1152/jappl.1996.81.3.1121] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We separated distal (turbulence-related) and proximal (dead space washout-related) effects of tracheal gas insufflation (TGI) by comparing the effects of straight and inverted catheters. We reasoned that the inverted catheter was unlikely to remove CO2 from conducting airways distal to its orifice. In six normal dogs during TGI at 10 l/min, advancing the catheters from 10 to 1 cm above the main carina decreased dead space volume by 29 +/- 12 and 12 +/- 6 ml (P < 0.04) with the straight and inverted catheters, respectively. By comparison, the tracheal volume between 10 and 1 cm above the carina was 15 +/- 2 ml. In another set of dogs (n = 5), we examined the distal effects of TGI before and after oleic acid-induced lung injury. During TGI at 10 l/min before and after oleic acid injury, the differences in arterial PCO2 between the straight and inverted catheters were 5 +/- and 9 +/- 6 Torr (P < 0.18), respectively. Our data suggest that distal effects of TGI become more pronounced as the catheter tip is positioned closer to the main carina. The distal effects of TGI were not diminished after oleic acid injury when minute ventilation was maintained constant.
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Affiliation(s)
- A Nahum
- Pulmonary and Critical Care Department, University of Minnesota, St. Paul-Ramsey Medical Center 55101, USA
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Ravenscraft SA, Shapiro RS, Nahum A, Burke WC, Adams AB, Nakos G, Marini JJ. Tracheal gas insufflation: catheter effectiveness determined by expiratory flush volume. Am J Respir Crit Care Med 1996; 153:1817-24. [PMID: 8665040 DOI: 10.1164/ajrccm.153.6.8665040] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Used adjunctively during mechanical ventilation, tracheal gas insufflation (TGI) improves CO2 elimination, principally by decreasing effective anatomic dead space. Continuing lung deflation at end- expiration raises the end-expiratory C02 concentration within the proximal airway, and could theoretically reduce the efficiency of a given catheter flow. To test this possibility, we designed a series of experiments that examined the influence of TGI delivery patterns on the efficiency of CO2 elimination. Using a gating device, catheter flow was delivered selectively during desired portions of expiration. Paralyzed, ventilated dogs were studied at short and extended inspiratory time fractions (TI/TT) with inspiratory tidal volume and ventilator frequency held constant. The expiratory flush volume, not the pattern of gas delivery, determined the observed decline in PaCO2, provided that the end-expiratory period was included in the catheter flush period. Despite continuing end-expiratory lung deflation (extended TI/TT), catheter effectiveness remained the same at matched expiratory flush volumes. To determine if enhanced distal mixing at the higher catheter flows required during the extended TI/TT (to match expiratory flush volume) masked a decrease in efficiency, we repeated the experiment with a tip-inverted catheter. We again found that matched catheter delivered expiratory volumes were similarly effective. With or without ongoing lung deflation, the volume of gas flushed during the expiratory period determined the effectiveness of TGI, provided that inspired minute ventilation remains unchanged and end-expiration is included in the catheter flush period.
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Affiliation(s)
- S A Ravenscraft
- Department of Pulmonary and Critical Care Medicine, University of Minnesota, St. Paul-Ramsey Medical Center, St. Paul 55101-2595, USA
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Affiliation(s)
- J J Marini
- University of Minnesota, Pulmonary Critical Care, St. Paul-Ramsey Medical Center, St. Paul, MN, USA
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Nahum A, Ravenscraft SA, Adams AB, Marini JJ. Inspiratory tidal volume sparing effects of tracheal gas insufflation in dogs with oleic acid-induced lung injury. J Crit Care 1995; 10:115-21. [PMID: 7496448 DOI: 10.1016/0883-9441(95)90002-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
PURPOSE Tracheal gas insufflation (TGI) improves the efficiency of conventional mechanical ventilation (CMV) by reducing the series dead space of the airways. Consequently, application of TGI as an adjunct to CMV may permit reducing tidal volume (VT) while limiting CO2 retention. We tested the extent to which panexpiratory TGI allows reduction of VT while maintaining PaCO2 constant in an oleic acid-induced lung injury model. METHODS We studied six anesthetized, paralyzed, and mechanically ventilated dogs. Oleic acid injury was induced by injecting 0.09 mL/kg of oleic acid into the right atrium. After stabilization of lung injury the VT-sparing effect of TGI was tested by progressively increasing catheter flow rate (Vc) from 2 to 5, 10, and 15 L/min while decreasing VT by an amount that maintained PaCO2 constant (approximately 47 mm Hg) with respect to baseline (Vc = 0 L/min). RESULTS Tidal volume was decreased from a baseline value of 0.360 +/- 0.030 L to 0.238 +/- 0.054 L at Vc of 15 L/min. The reduction in VT was associated with a decrement in peak and end-inspiratory plateau airway opening pressure from 32 +/- 3 to 28 +/- 6 cm H2O and from 25 +/- 2 to 21 +/- 3 cm H2O, respectively. Total physiological dead space fraction decreased from a baseline value of 0.60 +/- 0.08 to 0.31 +/- 0.20 during TGI at 15 L/min. TGI did not affect cardiac output, PaO2, or pulmonary venous admixture. CONCLUSION We conclude that TGI can be a useful adjunct to CMV during acute lung injury to limit VT while avoiding CO2 retention.
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Affiliation(s)
- A Nahum
- Department of Pulmonary and Critical Care, St Paul-Ramsey Medical Center, University of Minnesota 55101-2595, USA
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