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Georgopoulos D, Bolaki M, Stamatopoulou V, Akoumianaki E. Respiratory drive: a journey from health to disease. J Intensive Care 2024; 12:15. [PMID: 38650047 DOI: 10.1186/s40560-024-00731-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Abstract
Respiratory drive is defined as the intensity of respiratory centers output during the breath and is primarily affected by cortical and chemical feedback mechanisms. During the involuntary act of breathing, chemical feedback, primarily mediated through CO2, is the main determinant of respiratory drive. Respiratory drive travels through neural pathways to respiratory muscles, which execute the breathing process and generate inspiratory flow (inspiratory flow-generation pathway). In a healthy state, inspiratory flow-generation pathway is intact, and thus respiratory drive is satisfied by the rate of volume increase, expressed by mean inspiratory flow, which in turn determines tidal volume. In this review, we will explain the pathophysiology of altered respiratory drive by analyzing the respiratory centers response to arterial partial pressure of CO2 (PaCO2) changes. Both high and low respiratory drive have been associated with several adverse effects in critically ill patients. Hence, it is crucial to understand what alters the respiratory drive. Changes in respiratory drive can be explained by simultaneously considering the (1) ventilatory demands, as dictated by respiratory centers activity to CO2 (brain curve); (2) actual ventilatory response to CO2 (ventilation curve); and (3) metabolic hyperbola. During critical illness, multiple mechanisms affect the brain and ventilation curves, as well as metabolic hyperbola, leading to considerable alterations in respiratory drive. In critically ill patients the inspiratory flow-generation pathway is invariably compromised at various levels. Consequently, mean inspiratory flow and tidal volume do not correspond to respiratory drive, and at a given PaCO2, the actual ventilation is less than ventilatory demands, creating a dissociation between brain and ventilation curves. Since the metabolic hyperbola is one of the two variables that determine PaCO2 (the other being the ventilation curve), its upward or downward movements increase or decrease respiratory drive, respectively. Mechanical ventilation indirectly influences respiratory drive by modifying PaCO2 levels through alterations in various parameters of the ventilation curve and metabolic hyperbola. Understanding the diverse factors that modulate respiratory drive at the bedside could enhance clinical assessment and the management of both the patient and the ventilator.
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Affiliation(s)
| | - Maria Bolaki
- Department of Intensive Care Medicine, University Hospital of Heraklion, Heraklion, Crete, Greece
| | - Vaia Stamatopoulou
- Department of Pulmonary Medicine, University Hospital of Heraklion, Heraklion , Crete, Greece
| | - Evangelia Akoumianaki
- Medical School, University of Crete, Heraklion, Crete, Greece
- Department of Intensive Care Medicine, University Hospital of Heraklion, Heraklion, Crete, Greece
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How to ventilate obstructive and asthmatic patients. Intensive Care Med 2020; 46:2436-2449. [PMID: 33169215 PMCID: PMC7652057 DOI: 10.1007/s00134-020-06291-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 10/12/2020] [Indexed: 11/11/2022]
Abstract
Exacerbations are part of the natural history of chronic obstructive pulmonary disease and asthma. Severe exacerbations can cause acute respiratory failure, which may ultimately require mechanical ventilation. This review summarizes practical ventilator strategies for the management of patients with obstructive airway disease. Such strategies include non-invasive mechanical ventilation to prevent intubation, invasive mechanical ventilation, from the time of intubation to weaning, and strategies intended to prevent post-extubation acute respiratory failure. The role of tracheostomy, the long-term prognosis, and potential future adjunctive strategies are also discussed. Finally, the physiological background that underlies these strategies is detailed.
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Damiani LF, Bruhn A, Retamal J, Bugedo G. Patient-ventilator dyssynchronies: Are they all the same? A clinical classification to guide actions. J Crit Care 2020; 60:50-57. [PMID: 32739760 DOI: 10.1016/j.jcrc.2020.07.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 07/06/2020] [Accepted: 07/13/2020] [Indexed: 11/18/2022]
Abstract
Patient ventilatory dyssynchrony (PVD) is a mismatch between the respiratory drive of the patient and ventilatory assistance. It is a complex event seen in almost all ventilated patients and at any ventilator mode, with uncertain significance and prognosis. Due to its different pathophysiological mechanisms, there is still not consensual classification to guide us in selecting the best treatment. In the present review we aimed to summarize some clinical data on PVD, and to propose a clinical classification based on the type of PVD, from potentially innocuous to clearly harmful PVD, which could help clinicians in the decision-making process from adjusting ventilator settings to deeply sedate or paralyze the patient. Clearly, further studies are needed addressing risk factors, physiologic mechanisms and direct consequences of PVD in order to help clinicians to design effective and proven strategies at the bedside.
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Affiliation(s)
- L Felipe Damiani
- Departamento Ciencias de la Salud, Carrera de Kinesiología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Chile; Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Chile.
| | - Alejandro Bruhn
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Chile
| | - Jaime Retamal
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Chile
| | - Guillermo Bugedo
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Chile
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Natalini G, Tuzzo D, Rosano A, Testa M, Grazioli M, Pennestrì V, Amodeo G, Berruto F, Fiorillo M, Peratoner A, Tinnirello A, Filippini M, Marsilia PF, Minelli C, Bernardini A. Effect of external PEEP in patients under controlled mechanical ventilation with an auto-PEEP of 5 cmH2O or higher. Ann Intensive Care 2016; 6:53. [PMID: 27306887 PMCID: PMC4909663 DOI: 10.1186/s13613-016-0158-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 06/05/2016] [Indexed: 12/16/2022] Open
Abstract
Background In some patients with auto-positive end-expiratory pressure (auto-PEEP), application of PEEP lower than auto-PEEP maintains a constant total PEEP, therefore reducing the inspiratory threshold load without detrimental cardiovascular or respiratory effects. We refer to these patients as “complete PEEP-absorbers.” Conversely, adverse effects of PEEP application could occur in patients with auto-PEEP when the total PEEP rises as a consequence. From a pathophysiological perspective, all subjects with flow limitation are expected to be “complete PEEP-absorbers,” whereas PEEP should increase total PEEP in all other patients. This study aimed to empirically assess the extent to which flow limitation alone explains a “complete PEEP-absorber” behavior (i.e., absence of further hyperinflation with PEEP), and to identify other factors associated with it. Methods One hundred patients with auto-PEEP of at least 5 cmH2O at zero end-expiratory pressure (ZEEP) during controlled mechanical ventilation were enrolled. Total PEEP (i.e., end-expiratory plateau pressure) was measured both at ZEEP and after applied PEEP equal to 80 % of auto-PEEP measured at ZEEP. All measurements were repeated three times, and the average value was used for analysis. Results Forty-seven percent of the patients suffered from chronic pulmonary disease and 52 % from acute pulmonary disease; 61 % showed flow limitation at ZEEP, assessed by manual compression of the abdomen. The mean total PEEP was 7 ± 2 cmH2O at ZEEP and 9 ± 2 cmH2O after the application of PEEP (p < 0.001). Thirty-three percent of the patients were “complete PEEP-absorbers.” Multiple logistic regression was used to predict the behavior of “complete PEEP-absorber.” The best model included a respiratory rate lower than 20 breaths/min and the presence of flow limitation. The predictive ability of the model was excellent, with an overoptimism-corrected area under the receiver operating characteristics curve of 0.89 (95 % CI 0.80–0.97). Conclusions Expiratory flow limitation was associated with both high and complete “PEEP-absorber” behavior, but setting a relatively high respiratory rate on the ventilator can prevent from observing complete “PEEP-absorption.” Therefore, the effect of PEEP application in patients with auto-PEEP can be accurately predicted at the bedside by measuring the respiratory rate and observing the flow-volume loop during manual compression of the abdomen.
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Affiliation(s)
- Giuseppe Natalini
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy.
| | - Daniele Tuzzo
- Department of Anesthesia and Intensive Care, Spedali Civili Hospital, Brescia, Italy
| | - Antonio Rosano
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Marco Testa
- Department of Anesthesia and Intensive Care, SS. Annunziata Hospital, Savigliano, Italy
| | - Michele Grazioli
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
| | - Vincenzo Pennestrì
- Department of Anesthesia and Intensive Care, Misericordia Hospital, Grosseto, Italy
| | - Guido Amodeo
- Department of Anesthesia and Intensive Care, San Giovanni Bosco Hospital, Naples, Italy
| | - Francesco Berruto
- Department of Anesthesia and Intensive Care, Agnelli Hospital, Pinerolo, Italy
| | - Marialinda Fiorillo
- Department of Anesthesia and Intensive Care, Santa Maria degli Angeli Hospital, Pordenone, Italy
| | - Alberto Peratoner
- Department of Anesthesia and Intensive Care, Cattinara Hospital, Trieste, Italy
| | - Andrea Tinnirello
- Department of Anesthesia and Intensive Care, Mellino Mellini Hospital, Chiari, Italy
| | - Matteo Filippini
- Department of Anesthesia, Critical Care Medicine and Emergency, University of Brescia at Spedali Civili, Brescia, Italy
| | - Paolo F Marsilia
- Department of Anesthesia and Intensive Care, Cardarelli Hospital, Naples, Italy
| | - Cosetta Minelli
- Respiratory Epidemiology, Occupational Medicine and Public Health, Imperial College, London, UK
| | - Achille Bernardini
- Department of Anesthesia and Intensive Care, Fondazione Poliambulanza Hospital, Brescia, Italy
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Bihari S, Bersten AD. Chronic heart failure modifies the response to positive end-expiratory pressure in patients with chronic obstructive pulmonary disease. J Crit Care 2012; 27:639-46. [DOI: 10.1016/j.jcrc.2012.03.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 03/15/2012] [Accepted: 03/18/2012] [Indexed: 11/24/2022]
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Holanda MA, Fortaleza SC, Alves-de-Almeida M, Winkeler GF, Reis RC, Felix JH, Lima JW, Pereira ED. Continuous Positive Airway Pressure Effects on Regional Lung Aeration in Patients With COPD. Chest 2010; 138:305-14. [DOI: 10.1378/chest.09-2850] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Jezler S, Holanda MA, José A, Franca S. [Mechanical ventilation in decompensated chronic obstructive pulmonary disease (COPD)]. J Bras Pneumol 2008; 33 Suppl 2S:S111-8. [PMID: 18026669 DOI: 10.1590/s1806-37132007000800006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Guerin C, Fassier T, Bayle F, Lemasson S, Richard JC. Inhaled bronchodilator administration during mechanical ventilation: how to optimize it, and for which clinical benefit? J Aerosol Med Pulm Drug Deliv 2008; 21:85-96. [PMID: 18518835 DOI: 10.1089/jamp.2007.0630] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bronchodilators are frequently used in ICU patients, and are the most common medications administered by inhalation during mechanical ventilation. The amount of bronchodilator that deposits at its site of action depends on the amount of drug, inhaled mass, deposited mass, and particle size distribution. Mechanical ventilation challenges both inhaled mass and lung deposition by specific features, such as a ventilatory circuit, an endotracheal tube, and ventilator settings. Comprehensive in vitro studies have shown that an endotracheal tube is not as significant a barrier for the drug to travel as anticipated. Key variables of drug deposition are attachments of the inhalation device in the inspiratory line 10 to 30 cm to the endotracheal tube, use of chamber with metered-dose inhaler, dry air, high tidal volume, low respiratory frequency, and low inspiratory flow, which can increase the drug deposition. In vivo studies showed that a reduction by roughly 15% of the respiratory resistance was achieved with inhaled bronchodilators during invasive mechanical ventilation. The role of ventilatory settings is not as clear in vivo, and primary factors for optimal delivery and physiologic effects were medication dose and device location. Nebulizers and pressurized metered-dose inhalers can equally achieve physiologic end points. The effects of bronchodilators should be carefully evaluated, which can easily be done with the interrupter technique. With the non-invasive ventilation, the data regarding drug delivery and physiologic effects are still limited. With the bilevel ventilators the inhalation device should be located between the leak port and face mask. Further studies should investigate the effects of inhaled bronchodilators on patient outcome and methods to optimize delivery of inhaled bronchodilators during non-invasive ventilation.
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SOARES SM, OLIVEIRA RA, FRANCA SA, REZENDE SM, DRAGOSAVAC D, KACMAREK RM, CARVALHO CR. Continuous positive airway pressure increases inspiratory capacity of COPD patients. Respirology 2008; 13:387-93. [DOI: 10.1111/j.1440-1843.2008.01263.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
Mechanical ventilatory support allows patients who have CAO to gain time for pharmacologic treatment to work and to avoid and/or recover from respiratory muscle fatigue. The cornerstone to avoiding associated morbidity with mechanical ventilation in these patients is to prevent dynamic hyperinflation of the lung by limiting minute ventilation and maximizing time for expiration and by inducing synchronization between the patient and mechanical ventilator. When mechanical ventilation is necessary, NPPV should be considered first, whenever possible, in these patients. Patients who have CAO requiring mechanical ventilatory support have an increased risk of death following such an event. Therefore, careful followup is needed after hospital discharge.
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Affiliation(s)
- Younsuck Koh
- Division of Pulmonary and Critical Care Medicine, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap Dong Songpa-Ku, Seoul 138-736, Korea.
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12
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Georgopoulos D, Prinianakis G, Kondili E. Bedside waveforms interpretation as a tool to identify patient-ventilator asynchronies. Intensive Care Med 2005; 32:34-47. [PMID: 16283171 DOI: 10.1007/s00134-005-2828-5] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Accepted: 09/08/2005] [Indexed: 11/30/2022]
Abstract
OBJECTIVE During assisted modes of ventilatory support the ventilatory output is the final expression of the interaction between the ventilator and the patient's controller of breathing. This interaction may lead to patient-ventilator asynchrony, preventing the ventilator from achieving its goals, and may cause patient harm. Flow, volume, and airway pressure signals are significantly affected by patient-ventilator interaction and may serve as a tool to guide the physician to take the appropriate action to improve the synchrony between patient and ventilator. This review discusses the basic waveforms during assisted mechanical ventilation and how their interpretation may influence the management of ventilated patients. The discussion is limited on waveform eye interpretation of the signals without using any intervention which may interrupt the process of mechanical ventilation. DISCUSSION Flow, volume, and airway pressure may be used to (a) identify the mode of ventilator assistance, triggering delay, ineffective efforts, and autotriggering, (b) estimate qualitatively patient's respiratory efforts, and (c) recognize delayed and premature opening of exhalation valve. These signals may also serve as a tool for gross estimation of respiratory system mechanics and monitor the effects of disease progression and various therapeutic interventions. CONCLUSIONS Flow, volume, and airway pressure waveforms are valuable real-time tools in identifying various aspects of patient-ventilator interaction.
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Affiliation(s)
- Dimitris Georgopoulos
- Intensive Care Medicine Department, University Hospital of Heraklion, University of Crete, Heraklion, Crete, Greece.
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Carrera M, Sala E, Cosío BG, Agustí AGN. [Hospital treatment of chronic obstructive pulmonary disease exacerbations: an evidence-based review]. Arch Bronconeumol 2005; 41:220-9. [PMID: 15826532 DOI: 10.1016/s1579-2129(06)60427-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- M Carrera
- Servicio de Neumología, Hospital Universitario Son Dureta, Palma de Mallorca, Baleares, España
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Glérant JC, Leleu O, Rose D, Mayeux I, Jounieaux V. Oxygen consumption and PEEPe in ventilated COPD patients. Respir Physiol Neurobiol 2005; 146:117-24. [PMID: 15766900 DOI: 10.1016/j.resp.2004.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2004] [Indexed: 10/26/2022]
Abstract
The intrinsic positive-end-expiratory pressure (PEEPi) increases the inspiratory load, the cost of breathing and thus oxygen consumption (V(O2)). It has been shown that applying an extrinsic positive-end-expiratory pressure (PEEPe) reduces the inspiratory threshold load but the optimal PEEPe level is still in debate. We hypothesize that the best level of PEEPe could induce a decrease in V(O2) by reducing the V(O2) demands from PEEPi. Nine mechanically ventilated COPD patients were included. The level of PEEPe was determined in accordance with the static PEEPi. V(O2) was measured using an automatic gas analyser during synchronized intermittent mandatory ventilation (SIMV): without PEEPe, with a PEEPe equal to 50% of static PEEPi and with a PEEPe equal to 100% of static PEEPi. Static PEEPi appeared to be significantly correlated with the degree of airflow obstruction (FEV1) (P<0.05). Applying a PEEPe equal to static PEEPi resulted in a significant decrease in V(O2) (P<0.05) whereas the change in V(O2) proved to be unpredictable for a PEEPe level of 50% of static PEEPi. In conclusion, V(O2) decreases progressively when increasing PEEPe up to a level equal to 100% of static PEEPi. Thus, in mechanically ventilated COPD patients with a FEV1 < or = 1000 ml, applying a PEEPe of 5 cmH2O should be recommended.
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Affiliation(s)
- J-Ch Glérant
- Respiratory Department and Intensive Care Unit, 80054 Amiens Cedex 1, France
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Carrera M, Sala E, Cosío B, Agustí A. Tratamiento hospitalario de los episodios de agudización de la EPOC. Una revisión basada en la evidencia. Arch Bronconeumol 2005. [DOI: 10.1157/13073172] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Stark-Leyva KN, Beck KC, Johnson BD. Influence of expiratory loading and hyperinflation on cardiac output during exercise. J Appl Physiol (1985) 2004; 96:1920-7. [PMID: 14729724 DOI: 10.1152/japplphysiol.00756.2003] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Patients with obstructive lung disease are exposed to expiratory loads (ELs) and dynamic hyperinflation as a consequence of expiratory flow limitation. To understand how these alterations in lung mechanics might affect cardiac function, we examined the influence of a 10-cmH2O EL, alone and in combination with voluntary hyperinflation (ELH), on pulmonary pressures [esophageal (Pes) and gastric (Pg)] and cardiac output (CO) in seven healthy subjects. CO was determined by using an acetylene method at rest and at 40 and 70% of peak work. At rest and during exercise, EL resulted in an increase in Pes and Pg (7-18 cmH2O; P < 0.05) and a decrease in CO (from 5.3 ± 1.8 to 4.5 ± 1.4, 12.2 ± 2.2 to 11.2 ± 2.2, and 16.3 ± 3.3 to 15.2 ± 3.2 l/min for rest, 40% peak work, and 70% peak work, respectively; P < 0.05), which remained depressed after an additional 2 min of EL. With ELH, CO increased at rest and both exercise loads (relative to EL only) but remained below control values. The changes in CO were due to a reduction in stroke volume with a tendency for stroke volume to fall further with prolonged EL. There was a negative correlation between CO and the increase in expiratory Pes and Pg with EL ( R = -0.58 and -0.60; P < 0.01), whereas the rise in CO with subsequent hyperinflation was related to a more negative Pes ( R = 0.72; P < 0.01). In conclusion, EL leads to a reduction in CO, which appears to be primarily related to increases in expiratory abdominal and intrathoracic pressure, whereas ELH resulted in an improved CO, suggesting that lung inflation has little impact on cardiac function.
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Affiliation(s)
- Kristy N Stark-Leyva
- Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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Kondili E, Alexopoulou C, Prinianakis G, Xirouchaki N, Georgopoulos D. Pattern of lung emptying and expiratory resistance in mechanically ventilated patients with chronic obstructive pulmonary disease. Intensive Care Med 2004; 30:1311-8. [PMID: 15054570 DOI: 10.1007/s00134-004-2255-z] [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] [Received: 09/10/2003] [Accepted: 02/17/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVES To study the pattern of lung emptying and expiratory resistance in mechanically ventilated patients with chronic obstructive pulmonary disease (COPD). DESIGN A prospective physiological study. SETTING A 12-bed Intensive Care Unit. PATIENTS Ten patients with acute exacerbation of COPD. INTERVENTIONS At three levels of positive end-expiratory pressure (PEEP, 0, 5 and 10 cm H(2)O) tracheal (Ptr) and airway pressures, flow (V') and volume (V) were continuously recorded during volume control ventilation and airway occlusions at different time of expiration. MEASUREMENTS AND RESULTS V-V' curves during passive expiration were obtained, expired volume was divided into five equal volume slices and the time constant (tau) and dynamic deflation compliance (Crs(dyn)) of each slice was calculated by regression analysis of V-V' and post-occlusion V-Ptr relationships, respectively. In each volume slice the existence or not of flow limitation was examined by comparing V-V' curves with and without decreasing Ptr. For a given slice total expiratory resistance was calculated as tau/Crs(dyn), whereas expiratory resistance (Rrs) and time constant (tau(rs)) of the respiratory system were subsequently estimated taken into consideration the presence of flow limitation. At zero PEEP, tau(rs) increased significantly toward the end of expiration due to an increase in Rrs. PEEP significantly decreased Rrs at the end of expiration and resulted in a faster and relatively constant rate of lung emptying. CONCLUSIONS Patients with COPD exhibit a decrease in the rate of lung emptying toward the end of expiration due to an increase in Rrs. PEEP decreases Rrs, resulting in a faster and uniform rate of lung emptying.
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Affiliation(s)
- Eumorfia Kondili
- Department of Intensive Care Medicine, University Hospital of Heraklion, University of Crete, 711 10 Heraklion, Crete, Greece
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Jolliet P, Watremez C, Roeseler J, Ngengiyumva JC, de Kock M, Clerbaux T, Tassaux D, Reynaert M, Detry B, Liistro G. Comparative effects of helium-oxygen and external positive end-expiratory pressure on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in mechanically ventilated patients with chronic obstructive pulmonary disease. Intensive Care Med 2003; 29:1442-50. [PMID: 12851764 DOI: 10.1007/s00134-003-1864-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2002] [Accepted: 05/18/2003] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To compare the effects of He/O(2) and external PEEP (PEEPe) on intrinsic PEEP (PEEPi), respiratory mechanics, gas exchange, and ventilation/perfusion (V(A)/Q) in mechanically ventilated COPD patients. DESIGN AND SETTING Prospective, interventional study in the intensive care unit of a university hospital. INTERVENTIONS Ten intubated, sedated, paralyzed, mechanically ventilated COPD patients studied in the following conditions: (a) baseline settings made by clinician in charge, air/O(2), ZEEP; (b) He/O(2), ZEEP; (c) air/O(2), ZEEP; (d) air/O(2), PEEPe 80% of PEEPi. Measurements at each condition included V(A)/Q by the multiple inert gas elimination technique (MIGET). RESULTS PEEPi and trapped gas volume were comparably reduced by He/O(2) (4.2+/-4 vs. 7.7+/-4 cmH(2)O and 98+/-82 vs. 217+/-124 ml, respectively) and PEEPe (4.4+/-1.3 vs. 7.8+/-3.6 cmH(2)O and 120+/-107 vs. 216+/-115 ml, respectively). He/O(2) reduced inspiratory and expiratory respiratory system resistance (15.5+/-4.4 vs. 20.7+/-6.9 and 19+/-9 vs. 28.8+/-15 cmH(2)O l(-1)s(-1), respectively) and plateau pressure (13+/-4 vs. 17+/-6 cmH(2)O). PEEPe increased airway pressures, including total PEEP, and elastance. PaO(2)/FIO(2) was slightly reduced by He/O(2) (225+/-83 vs. 245+/-82) without significant V(A)/Q change. CONCLUSIONS He/O(2) and PEEPe comparably reduced PEEPi and trapped gas volume. However, He/O(2) decreased airway resistance and intrathoracic pressures, at a small cost in arterial oxygenation. He/O(2) could offer an attractive option in COPD patients with PEEPi/dynamic hyperinflation.
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Affiliation(s)
- Philippe Jolliet
- Medical Intensive Care Division, University Hospital, 1211 Geneva 14, Switzerland.
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Vassiliou MP, Amygdalou A, Psarakis CJ, Dalavanga Y, Vassiliou PM, Mandragos KE, Constantopoulos SH, Behrakis PK. Volume and flow dependence of respiratory mechanics in mechanically ventilated COPD patients. Respir Physiol Neurobiol 2003; 135:87-96. [PMID: 12706068 DOI: 10.1016/s1569-9048(03)00064-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Volume and flow dependencies of respiratory mechanics are examined in 10 COPD patients under mechanical ventilation (MV) at 3 levels of externally applied PEEP (PEEPe). Airways pressure (Paw), flow (V') and volume (V) data are analyzed according to (1) the linear and (2) a non-linear model, accounting for volume dependence of elastance and for flow and volume dependence of resistance. The models' fitness to data is assessed by the regression errors. Non-linear modelling fits significantly better to data, while the difference of fitness decreases with PEEPe. Linear mechanics are not significantly different between the 3 levels of PEEPe. A positive volume dependence of elastance observed at 0, decreases at 5 and increases again at 10 hPa of PEEPe. A seriously negative volume dependence of resistance at 0 turned to positive with PEEPe. These dependencies of respiratory mechanics during COPD under MV, show that the present non-linear respiratory mechanical monitoring may help for better and less risky adjustment of PEEPe.
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Affiliation(s)
- Miltos P Vassiliou
- The Pneumonology Department, Medical School, University of Ioannina, Ioannina, Greece.
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O'Donoghue FJ, Catcheside PG, Jordan AS, Bersten AD, McEvoy RD. Effect of CPAP on intrinsic PEEP, inspiratory effort, and lung volume in severe stable COPD. Thorax 2002; 57:533-9. [PMID: 12037230 PMCID: PMC1746360 DOI: 10.1136/thorax.57.6.533] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Intrinsic positive end expiratory pressure (PEEPi) constitutes an inspiratory threshold load on the respiratory muscles, increasing work of breathing. The role of continuous positive airway pressure (CPAP) in alleviating PEEPi in patients with severe stable chronic obstructive pulmonary disease is uncertain. This study examined the effect of CPAP on the inspiratory threshold load, muscle effort, and lung volume in this patient group. METHODS Nine patients were studied at baseline and with CPAP increasing in increments of 1 cm H(2)O to a maximum of 10 cm H(2)O. Breathing pattern and minute ventilation (I), dynamic PEEPi, expiratory muscle activity, diaphragmatic (PTPdi/min) and oesophageal (PTPoes/min) pressure-time product per minute, integrated diaphragmatic (EMGdi) and intercostal EMG (EMGic) and end expiratory lung volume (EELV) were measured. RESULTS Expiratory muscle activity was present at baseline in one subject. In the remaining eight, PEEPi was reduced from a mean (SE) of 2.9 (0.6) cm H(2)O to 0.9 (0.1) cm H(2)O (p<0.05). In two subjects expiratory muscle activity contributed to PEEPi at higher pressures. There were no changes in respiratory pattern but I increased from 9.2 (0.6) l/min to 10.7 (1.1) l/min (p<0.05). EMGdi remained stable while EMGic increased significantly. PTPoes/min decreased, although this did not reach statistical significance. PTPdi/min decreased significantly from 242.1 (32.1) cm H(2)O.s/min to 112.9 (21.7) cm H(2)O.s/min). EELV increased by 1.1 (0.3) l (p<0.01). CONCLUSION High levels of CPAP reduce PEEPi and indices of muscle effort in patients with severe stable COPD, but only at the expense of substantial increases in lung volume.
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Affiliation(s)
- F J O'Donoghue
- Sleep Disorders Unit, Repatriation General Hospital, Daw Park, South Australia 5041. Fergal.O'
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21
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Affiliation(s)
- Y Koh
- Division of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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22
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Guérin C, Fournier G, Milic-Emili J. Effects of PEEP on inspiratory resistance in mechanically ventilated COPD patients. Eur Respir J 2001; 18:491-8. [PMID: 11589346 DOI: 10.1183/09031936.01.00072001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This study aimed to investigate the effect of increased lung volume with positive end-expiratory pressure (PEEP) on respiratory resistance in patients with chronic obstructive pulmonary disease (COPD). Ten patients with COPD were mechanically ventilated for acute respiratory failure. PEEP was set at 0, 5, 10 and 15 cm H2O. Using the rapid airway occlusion technique, the total inspiratory resistance of the respiratory system was partitioned into interrupter (Rint,rs) and additional effective (deltaRrs) resistances. At each level of PEEP, at constant inflation flow, the inflation volume (deltaV) was varied from 0.2-1 L, and, at constant deltaV, the inflation flow was varied from 0.2-1.2 L x s(-1). The changes in end-expiratory lung volume (deltaEELV) induced by PEEP were also measured. The difference between the EELV and the relaxation volume of the respiratory system (deltaFRC) increased significantly with PEEP of 10 and 15 cm H2O as compared to a PEEP of 0, the increase being associated with a significant reduction of Rint,rs. By contrast, deltaRrs was independent of deltaFRC. At constant deltaV, Rint,rs fitted Rohrer's equation (Rint,rs = K1 + K2 x flow). While K2 significantly declined with AFRC, K1 did not change. At all levels of PEEP, deltaRrs was not influenced by deltaFRC. With increasing lung volume induced by positive end-expiratory pressure, the inspiratory airway resistance decreased, whereas the viscoelastic behaviour of the respiratory system, as reflected by additional effective resistance, did not change.
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Affiliation(s)
- C Guérin
- Medical Intensive Care Unit, Lyon Sud Hospital and Claude Bernard Lyon I University, France
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23
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Abstract
Exacerbations of COPD are a leading indication for MV in the intensive care unit. A thorough understanding of the pathophysiology of AVF in COPD is critical for physicians caring for these patients. In particular, physicians should understand DHI and use the ventilator and ancillary techniques to minimize its impact. Noninvasive positive-pressure ventilation should be considered strongly in relatively stable patients with an adequate mental status and manageable secretions. Once AVF resolves, patients should be removed from the ventilator as soon as is safe to do so to minimize the adverse effects of prolonged MV. An organized approach to weaning and identifying patients capable of independent breathing is crucial. Most patients with COPD and AVF benefit from MV and generally return to or approach their premorbid functional status. A significant subset, however, will not benefit from, or choose not to undergo, MV. Deciding upon appropriate therapeutic options for these patients relies heavily on effective communication between physician and patient. Comprehensive discussions before the development of AVF can assist decision-making after respiratory failure develops.
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Affiliation(s)
- J M Sethi
- Department of Medicine, Section of Pulmonary and Critical Care, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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24
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Wrigge H, Putensen C. What is the "best PEEP" in chronic obstructive pulmonary disease? Intensive Care Med 2000; 26:1167-9. [PMID: 11089736 DOI: 10.1007/s001340000620] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Tassaux D, Jolliet P, Roeseler J, Chevrolet JC. Effects of helium-oxygen on intrinsic positive end-expiratory pressure in intubated and mechanically ventilated patients with severe chronic obstructive pulmonary disease. Crit Care Med 2000; 28:2721-8. [PMID: 10966241 DOI: 10.1097/00003246-200008000-00006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To test the hypothesis that replacing 70:30 nitrogen: oxygen (Air-O2) with 70:30 helium:oxygen (He-O2) can decrease dynamic hyperinflation ("intrinsic" positive end-expiratory pressure) in mechanically ventilated patients with chronic obstructive pulmonary disease (COPD), and to document the consequences of such an effect on arterial blood gases and hemodynamics. DESIGN Prospective, interventional study. SETTING Medical intensive care unit, university tertiary care center. PATIENTS Twenty-three intubated, sedated, paralyzed, and mechanically ventilated patients with COPD enrolled within 36 hrs after intubation. INTERVENTIONS Measurements were taken at the following time points, all with the same ventilator settings: a) baseline; b) after 45 mins with He-O2; c) 45 mins after return to Air-O2. The results were then compared to those obtained in a test lung model using the same ventilator settings. MAIN RESULTS (MEAN + SD): Trapped lung volume and intrinsic positive end-expiratory pressure decreased during He-O2 ventilation (215+/-125 mL vs. 99+/-15 mL and 9+/-2.5 cm H2O vs. 5+/-2.7 cm H2O, respectively; p < .05). Likewise, peak and mean airway pressures declined with He-O2 (30+/-5 cm H2O vs. 25+/-6 cm H2O and 8+/-2 cm H2O vs. 7+/-2 cm H2O, respectively; p < .05). These parameters all rose to their baseline values on return to Air-O2 (p < .05 vs. values during He-O2). These results were in accordance with those obtained in the test lung model. There was no modification of arterial blood gases, heart rate, or mean systemic arterial blood pressure. In 12/23 patients, a pulmonary artery catheter was in place, allowing hemodynamic measurements and venous admixture calculations. Switching to He-O2 and back to Air-O2 had no effect on pulmonary artery pressures, right and left ventricular filling pressures, cardiac output, pulmonary and systemic vascular resistance, or venous admixture. CONCLUSION In mechanically ventilated COPD patients with intrinsic positive end-expiratory pressure, the use of He-O2 can markedly reduce trapped lung volume, intrinsic positive end-expiratory pressure, and peak and mean airway pressures. No effect was noted on hemodynamics or arterial blood gases. He-O2 might prove beneficial in this setting to reduce the risk of barotrauma, as well as to improve hemodynamics and gas exchange in patients with very high levels of intrinsic positive end-expiratory pressure.
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Affiliation(s)
- D Tassaux
- Medical Intensive Care Division, University Hospital, Geneva, Switzerland
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26
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Georgopoulos D, Mouloudi E, Kondili E, Klimathianaki M. Bronchodilator delivery with metered-dose inhaler during mechanical ventilation. Crit Care 2000; 4:227-34. [PMID: 11094505 PMCID: PMC150040 DOI: 10.1186/cc698] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2000] [Accepted: 06/16/2000] [Indexed: 11/29/2022] Open
Abstract
The delivery of bronchodilators with metered-dose inhaler (MDI) in mechanically ventilated patients has attracted considerable interest in recent years. This is because the use of the MDI has several advantages over the nebulizer, such as reduced cost, ease of administration, less personnel time, reliability of dosing and a lower risk of contamination. A spacer device is fundamental in order to demonstrate the efficacy of the bronchodilatory therapy delivered by MDI. Provided that the technique of administration is appropriate, MDIs are as effective as nebulizers, despite a significantly lower dose of bronchodilator given by the MDI.
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Jain S, Hanania NA, Guntupalli KK. Ventilation of patients with asthma and obstructive lung disease. Crit Care Clin 1998; 14:685-705. [PMID: 9891633 DOI: 10.1016/s0749-0704(05)70026-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Mechanical ventilation in a patient with obstructive airway disease may be a lifesaving measure; however, it may also be associated with significant morbidity and mortality. It is important for a physician to be familiar with the potential complications of mechanical ventilation in this group of patients and to know how to avoid them by carefully applying safe ventilator strategies. The cornerstone of such strategies is to minimize minute ventilation, maximize time for expiration, and avoid hyperinflation of the lung. Several bedside parameters (iPEEP, VEI, Pplat) that reflect presence of gas trapping and potential hyperinflation may be measured. In addition to mechanical ventilation, management should include inhaled bronchodilators and systemic corticosteroid therapies. In the event controlled hypoventilation is necessary, sedation with or without the use of muscle relaxants may be required. Unconventional therapies such as the use of Heliox, magnesium sulfate, ketamine, and inhalational anesthetics may be attempted in severe cases that do not respond to conventional management. With appropriate use of ventilator strategies, a reduction in the mortality and morbidity of patients with obstructive airway disease requiring mechanical ventilation has recently been noted.
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Affiliation(s)
- S Jain
- Baylor College of Medicine, Houston, Texas, USA
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28
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Gladwin MT, Pierson DJ. Mechanical ventilation of the patient with severe chronic obstructive pulmonary disease. Intensive Care Med 1998; 24:898-910. [PMID: 9803325 DOI: 10.1007/s001340050688] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M T Gladwin
- Department of Critical Care Medicine, NIH, Bethesda, MD 20892, USA
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Uhlig T, Kondo T, Sly PD. Measurements of PEEP-induced changes in lung volume: evaluation of a laser monitor. Chest 1997; 112:107-12. [PMID: 9228364 DOI: 10.1378/chest.112.1.107] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
STUDY OBJECTIVE To evaluate a newly developed laser monitor in the measurement of positive end-expiratory pressure (PEEP)-induced changes in end-expiratory lung volume (EELV) in spontaneously breathing subjects. DESIGN An open comparison between two different methods to assess breathing parameters. SETTING A respiratory research unit. PARTICIPANTS Six spontaneously breathing, healthy volunteers. INTERVENTIONS Stepwise increases of PEEP from 0 to 0.8 to 1.6 kPa during spontaneous breathing; repeated validation of the laser monitor in each subject. MEASUREMENTS AND RESULTS Pressure and flow were recorded at the airway opening. Abdominal wall displacement (AWD) measured by the laser sensor was recorded simultaneously. The time lag between the volume and the laser signals during baseline was 0.068+/-0.052 s and during maximal PEEP, 0.108+/-0.093 s. There was no baseline drift in either the PEEP or the AWD signals. Mean EELV decreased by 290 mL to 1,157 mL after the PEEP valve was removed. Within each individual, the ratio between EELV and AWD showed only small variations. Measurements of tidal volume (VT) and AWD showed good agreement at all PEEP levels. Mean VT decreased in all but one subject during PEEP. With the increase in PEEP, the end-expiratory abdominal baseline increased linearly over a large range of end-expiratory pressures with a flattening of the curve at high PEEP levels in all subjects. CONCLUSIONS The laser monitor is sufficiently accurate for measuring PEEP-induced changes in EELV during spontaneous breathing in healthy adult subjects. Monitors incorporating multiple laser sensors may have considerable clinical promise.
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Affiliation(s)
- T Uhlig
- Division of Clinical Sciences, TVW Telethon Institute for Child Health Research, West Perth, Australia
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MacIntyre NR, Cheng KC, McConnell R. Applied PEEP during pressure support reduces the inspiratory threshold load of intrinsic PEEP. Chest 1997; 111:188-93. [PMID: 8996015 DOI: 10.1378/chest.111.1.188] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
OBJECTIVES Mechanical ventilation in patients with obstructive airway disease (OAD) is associated with the development of dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEPi). One of the effects of this form of PEEPi is to act as an inspiratory threshold load that can produce ineffective breath triggering, dyspnea, and muscle fatigue. Recently it has been shown that applying PEEP in the ventilator circuit can reduce this imposed triggering load. We wished to investigate this further by studying patients with OAD being weaned with pressure support (PS) ventilation. Our first objective was to determine the prevalence and magnitude of this form of PEEPi in OAD patients who were clinically judged to be capable of triggering mechanical ventilatory breaths. Our second objective was to attempt to reduce the triggering load by applying circuit PEEP and then observe the response of patient-ventilator interactions during the patient-triggered, pressure-limited PS breath. DESIGN Thirteen random patients with OAD who were receiving PS ventilation were studied by measuring airway pressures, airway gas flow, baseline esophageal pressure, esophageal pressure time products (PTP), and esophageal pressure changes before ventilator gas delivery began (delta Pes taken to represent PEEPi). Measurements were made at baseline and after stepwise increases in circuit PEEP up to the PEEPi. RESULTS We found measurable PEEPi in all patients (average +/- SD of 9.54 +/- 4.3 cm H2O) and it was > 10 cm H2O in seven patients. As would be predicted, we observed progressive reductions in PEEPi as applied PEEP was given. We also observed that the component of patient effort (PTP) related to overcoming PEEPi also decreased, but the PTP related to tidal volume (VT) did not. The VT associated with the set PS thus did not change with application of PEEP, nor did the breathing frequency. CONCLUSION PEEPi is common in OAD patients receiving mechanical ventilatory support. The imposed triggering load from PEEPi can be offset to large extent by circuit PEEP approaching the baseline PEEPi. Although total patient effort substantially falls with applied PEEP, the patient effort that combine with PS to effect VT does not.
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Affiliation(s)
- N R MacIntyre
- Duke University Medical Center, Durham, NC 27710, USA
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31
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Abstract
This article reviews selected topics relevant to the use of mechanical ventilation in patients with severe airflow obstruction. Areas discussed include the bedside assessment of respiratory system mechanics, the ventilatory determinants of dynamic pulmonary hyperinflation, the role of controlled hypoventilation with permissive hypercapnia, and the delivery of bronchodilators during mechanical ventilation.
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Affiliation(s)
- J W Leatherman
- Division of Pulmonary and Critical Care Medicine, University of Minnesota Medical School, Minneapolis, USA
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32
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Georgopoulos D, Mitrouska I, Markopoulou K, Patakas D, Anthonisen NR. Effects of breathing patterns on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation. Intensive Care Med 1995; 21:880-6. [PMID: 8636519 DOI: 10.1007/bf01712328] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To examine the circulatory and respiratory effects of breathing pattern in patients with chronic obstructive pulmonary disease (COPD) and dynamic hyperinflation (DH) during controlled mechanical ventilation. DESIGN Prospective, controlled, randomized, non-blinded study. SETTING Respiratory intensive care unit of a university hospital. PATIENTS Nine patients with acute respiratory failure and DH due to acute exacerbations of COPD. INTERVENTIONS Keeping tidal volume and total breath duration (TTOT) constant, patients were ventilated at six different values of expiratory time (TE). TE changes were randomly induced by alterations of constant inspiratory flow (VI) and/or end-inspiratory pause (EIP). Patients were studied at three levels of VI(0.93 +/- 0.08, 0.72 +/- 0.06 and 0.55 +/- 0.04 l/s, mean +/- SE), with and without EIP (10% of TTOT). MEASUREMENTS AND RESULTS Lung volumes, airflows, airways pressures, oxygenation indices and dead space were measured. Alveolar pressure and airway resistance (Rmin), as well as the additional resistance (delta R) due to viscoelastic pressure dissipation and time-constant inequalities, were estimated by rapid airway occlusion during inflation. In seven out of nine patients, right-heart catheterization was performed and hemodynamic parameters were obtained at each value of TE. A significant decrease of intrinsic positive end-expiratory pressure (PEEPi), end-inspiratory static and mean (mPaw) airway pressures, end-expiratory lung volume above passive FRC (Vtrap), delta R and venous admixture and a significant increase of peak airway pressure, Rmin, stroke volume index and mixed venous PO2 (PvO2) were observed when VI increased. At each VI, the addition of EIP significantly decreased iso-volume expiratory flows and PvO2 and increased Vtrap and mPaw. CONCLUSIONS We conclude that in mechanically ventilated patients with COPD, the pattern of lung inflation and TE alteration have a significant impact on respiratory system mechanics, gas exchange and hemodynamics. Addition of EIP in patients with COPD may be detrimental.
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Affiliation(s)
- D Georgopoulos
- Respiratory Failure Unit, G. Papanicolaou Hospital, University of Thessaloniki, Exohi, Greece
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Rossi A, Polese G, Brandi G, Conti G. Intrinsic positive end-expiratory pressure (PEEPi). Intensive Care Med 1995; 21:522-36. [PMID: 7560497 DOI: 10.1007/bf01706208] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- A Rossi
- Divisione di Pneumologia, Ospedale Maggiore di Borgo Trento, Verona, Italy
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