Patient-ventilator asynchrony during assisted mechanical ventilation
TL;DR: One-fourth of patients exhibit a high incidence of asynchrony during assisted ventilation, which is associated with a prolonged duration of mechanical ventilation and with excessive levels of ventilatory support.
Abstract: Objective
The incidence, pathophysiology, and consequences of patient-ventilator asynchrony are poorly known. We assessed the incidence of patient-ventilator asynchrony during assisted mechanical ventilation and we identified associated factors.
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McMaster University1, Copenhagen University Hospital2, King Saud bin Abdulaziz University for Health Sciences3, Albert Einstein College of Medicine4, University of Toronto5, Brown University6, Rhode Island Hospital7, Oklahoma State University Center for Health Sciences8, Utrecht University9, NewYork–Presbyterian Hospital10, Peking Union Medical College Hospital11, Sunnybrook Health Sciences Centre12, Humanitas University13, University of Ulsan14, National Institutes of Health15, Imperial College London16, United Arab Emirates University17, Population Health Research Institute18, St George’s University Hospitals NHS Foundation Trust19, Emory University Hospital20, University at Buffalo21, Baylor College of Medicine22, University of Milano-Bicocca23, King Abdulaziz Medical City24, King Saud Medical City25, The George Institute for Global Health26, Royal North Shore Hospital27, University of Virginia28, University of Washington29
TL;DR: The Surviving Sepsis Campaign CO VID-19 panel issued several recommendations to help support healthcare workers caring for critically ill ICU patients with COVID-19, and will provide new recommendations in further releases of these guidelines.
Abstract: The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a rapidly spreading illness, Coronavirus Disease 2019 (COVID-19), affecting thousands of people around the world. Urgent guidance for clinicians caring for the sickest of these patients is needed.
We formed a panel of 36 experts from 12 countries. All panel members completed the World Health Organization conflict of interest disclosure form. The panel proposed 53 questions that are relevant to the management of COVID-19 in the ICU. We searched the literature for direct and indirect evidence on the management of COVID-19 in critically ill patients in the ICU. We identified relevant and recent systematic reviews on most questions relating to supportive care. We assessed the certainty in the evidence using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach, then generated recommendations based on the balance between benefit and harm, resource and cost implications, equity, and feasibility. Recommendations were either strong or weak, or in the form of best practice recommendations.
The Surviving Sepsis Campaign COVID-19 panel issued 54 statements, of which 4 are best practice statements, 9 are strong recommendations, and 35 are weak recommendations. No recommendation was provided for 6 questions. The topics were: (1) infection control, (2) laboratory diagnosis and specimens, (3) hemodynamic support, (4) ventilatory support, and (5) COVID-19 therapy.
The Surviving Sepsis Campaign COVID-19 panel issued several recommendations to help support healthcare workers caring for critically ill ICU patients with COVID-19. When available, we will provide new recommendations in further releases of these guidelines.
1,762 citations
Cites background from "Patient-ventilator asynchrony durin..."
...Strict adherence to target Vt in spontaneously breathing patients with ARDS is a challenge; patient-ventilator dyssynchrony is not uncommon [101]....
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McMaster University1, Copenhagen University Hospital2, King Saud bin Abdulaziz University for Health Sciences3, Albert Einstein College of Medicine4, University of Toronto5, Brown University6, Utrecht University7, NewYork–Presbyterian Hospital8, Peking Union Medical College Hospital9, Sunnybrook Health Sciences Centre10, University of Ulsan11, National Institutes of Health12, Imperial College London13, United Arab Emirates University14, Humanitas University15, St George’s University Hospitals NHS Foundation Trust16, Emory University Hospital17, University at Buffalo18, Baylor College of Medicine19, University of Milano-Bicocca20, King Abdulaziz Medical City21, King Saud Medical City22, The George Institute for Global Health23, University of Virginia24, University of Washington25
TL;DR: A panel of 36 experts from 12 countries issued several recommendations to help support healthcare workers caring for critically ill ICU patients with COVID-19, and assessed the certainty in the evidence using the Grading of Recommendations, Assessment, Development and Evaluation approach.
Abstract: BACKGROUND: The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a rapidly spreading illness, Coronavirus Disease 2019 (COVID-19), affecting thousands of people around the world. Urgent guidance for clinicians caring for the sickest of these patients is needed. METHODS: We formed a panel of 36 experts from 12 countries. All panel members completed the World Health Organization conflict of interest disclosure form. The panel proposed 53 questions that are relevant to the management of COVID-19 in the ICU. We searched the literature for direct and indirect evidence on the management of COVID-19 in critically ill patients in the ICU. We identified relevant and recent systematic reviews on most questions relating to supportive care. We assessed the certainty in the evidence using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach, then generated recommendations based on the balance between benefit and harm, resource and cost implications, equity, and feasibility. Recommendations were either strong or weak, or in the form of best practice recommendations. RESULTS: The Surviving Sepsis Campaign COVID-19 panel issued 54 statements, of which four are best practice statements, nine are strong recommendations, and 35 are weak recommendations. No recommendation was provided for six questions. The topics were: 1) infection control, 2) laboratory diagnosis and specimens, 3) hemodynamic support, 4) ventilatory support, and 5) COVID-19 therapy. CONCLUSION: The Surviving Sepsis Campaign COVID-19 panel issued several recommendations to help support healthcare workers caring for critically ill ICU patients with COVID-19. When available, we will provide new evidence in further releases of these guidelines.
832 citations
Cites background from "Patient-ventilator asynchrony durin..."
...Strict adherence to target Vt in spontaneously breathing patients with ARDS is a challenge; patient-ventilator dyssynchrony is not uncommon (101)....
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TL;DR: For three aspects of ARDS management (driving pressure, early spontaneous ventilation, and extracorporeal carbon dioxide removal), the experts concluded that no sound recommendation was possible given current knowledge.
Abstract: Fifteen recommendations and a therapeutic algorithm regarding the management of acute respiratory distress syndrome (ARDS) at the early phase in adults are proposed. The Grade of Recommendation Assessment, Development and Evaluation (GRADE) methodology has been followed. Four recommendations (low tidal volume, plateau pressure limitation, no oscillatory ventilation, and prone position) had a high level of proof (GRADE 1 + or 1 −); four (high positive end-expiratory pressure [PEEP] in moderate and severe ARDS, muscle relaxants, recruitment maneuvers, and venovenous extracorporeal membrane oxygenation [ECMO]) a low level of proof (GRADE 2 + or 2 −); seven (surveillance, tidal volume for non ARDS mechanically ventilated patients, tidal volume limitation in the presence of low plateau pressure, PEEP > 5 cmH2O, high PEEP in the absence of deleterious effect, pressure mode allowing spontaneous ventilation after the acute phase, and nitric oxide) corresponded to a level of proof that did not allow use of the GRADE classification and were expert opinions. Lastly, for three aspects of ARDS management (driving pressure, early spontaneous ventilation, and extracorporeal carbon dioxide removal), the experts concluded that no sound recommendation was possible given current knowledge. The recommendations and the therapeutic algorithm were approved by the experts with strong agreement.
445 citations
Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico1, University of Milan2, Loyola University Chicago3, Harvard University4, University of Genoa5, University of Bari6, University of Lyon7, University of Turin8, University of Bologna9, Autonomous University of Barcelona10, University of Toronto11
TL;DR: The time is now right to apply the knowledge obtained with Pes to improve the management of critically ill and ventilator-dependent patients, as Pes measurements have enhanced the understanding of the pathophysiology of acute lung injury, patient-ventilator interaction, and weaning failure.
Abstract: This report summarizes current physiological and technical knowledge on esophageal pressure (Pes) measurements in patients receiving mechanical ventilation. The respiratory changes in Pes are representative of changes in pleural pressure. The difference between airway pressure (Paw) and Pes is a valid estimate of transpulmonary pressure. Pes helps determine what fraction of Paw is applied to overcome lung and chest wall elastance. Pes is usually measured via a catheter with an air-filled thin-walled latex balloon inserted nasally or orally. To validate Pes measurement, a dynamic occlusion test measures the ratio of change in Pes to change in Paw during inspiratory efforts against a closed airway. A ratio close to unity indicates that the system provides a valid measurement. Provided transpulmonary pressure is the lung-distending pressure, and that chest wall elastance may vary among individuals, a physiologically based ventilator strategy should take the transpulmonary pressure into account. For monitoring purposes, clinicians rely mostly on Paw and flow waveforms. However, these measurements may mask profound patient-ventilator asynchrony and do not allow respiratory muscle effort assessment. Pes also permits the measurement of transmural vascular pressures during both passive and active breathing. Pes measurements have enhanced our understanding of the pathophysiology of acute lung injury, patient-ventilator interaction, and weaning failure. The use of Pes for positive end-expiratory pressure titration may help improve oxygenation and compliance. Pes measurements make it feasible to individualize the level of muscle effort during mechanical ventilation and weaning. The time is now right to apply the knowledge obtained with Pes to improve the management of critically ill and ventilator-dependent patients.
428 citations
TL;DR: After prolonged controlled mechanical ventilation, neurally adjusted ventilator assist improves diaphragm efficiency whereas pressure support ventilation does not.
Abstract: Prolonged controlled mechanical ventilation depresses diaphragmatic efficiency. Assisted modes of ventilation should improve it. We assessed the impact of pressure support ventilation versus neurally adjusted ventilator assist on diaphragmatic efficiency. Patients previously ventilated with controlled mechanical ventilation for 72 hours or more were randomized to be ventilated for 48 hours with pressure support ventilation (n =12) or neurally adjusted ventilatory assist (n = 13). Neuro-ventilatory efficiency (tidal volume/diaphragmatic electrical activity) and neuro-mechanical efficiency (pressure generated against the occluded airways/diaphragmatic electrical activity) were measured during three spontaneous breathing trials (0, 24 and 48 hours). Breathing pattern, diaphragmatic electrical activity and pressure time product of the diaphragm were assessed every 4 hours. In patients randomized to neurally adjusted ventilator assist, neuro-ventilatory efficiency increased from 27 ± 19 ml/μV at baseline to 62 ± 30 ml/μV at 48 hours (p <0.0001) and neuro-mechanical efficiency increased from 1 ± 0.6 to 2.6 ± 1.1 cmH2O/μV (p = 0.033). In patients randomized to pressure support ventilation, these did not change. Electrical activity of the diaphragm, neural inspiratory time, pressure time product of the diaphragm and variability of the breathing pattern were significantly higher in patients ventilated with neurally adjusted ventilatory assist. The asynchrony index was 9.48 [6.38– 21.73] in patients ventilated with pressure support ventilation and 5.39 [3.78– 8.36] in patients ventilated with neurally adjusted ventilatory assist (p = 0.04). After prolonged controlled mechanical ventilation, neurally adjusted ventilator assist improves diaphragm efficiency whereas pressure support ventilation does not. ClinicalTrials.gov study registration: NCT0247317
, 06/11/2015.
358 citations
Cites methods or result from "Patient-ventilator asynchrony durin..."
...These results are important in view of recent reports showing the correlation of the AI with clinically meaningful outcome parameters [13, 14]....
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...According to Thille and coworkers, the asynchronies were classified into six types: a) ineffective triggering (missed effort); b) ineffective inspiratory triggering; c) double-triggering; d) auto-triggering; e) prolonged cycle; f ) short cycle [13]....
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References
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TL;DR: The ESICM developed a so-called sepsis-related organ failure assessment (SOFA) score to describe quantitatively and as objectively as possible the degree of organ dysfunction/failure over time in groups of patients or even in individual patients.
Abstract: Multiple organ failure (MOF) is a major cause of morbidity and mortali ty in the critically ill patient. Emerging in the 1970s, the concept of MOF was linked to modern developments in intensive care medicine [1]. Although an uncontrolled infection can lead to MOF [2], such a phenomenon is not always found. A number of mediators and the persistence of tissue hypoxia have been incriminated in the development of MOF [3]. The gut has been cited as a possible \"moto r \" of MOF [4]. Nevertheless, our knowledge regarding the pathophysiology of MOF remains limited. Furthermore, the development of new therapeutic interventions aiming at a reduction of the incidence and severity of organ failure calls for a better definition of the severity of organ dysfunction/failure to quantify the severity of illness. Accordingly, it is important to set some simple but objective criteria to define the degree of organ dysfunction/failure. The evolution of our knowledge of organ dysfunction/failure led us to establish several principles: 1. Organ dysfunction/failure is a process rather than an event. Hence, it should be seen as a continuum and should not be described simply as \"present\" or \"absent~' Hence, the assessment should be based on a scale. 2. The time factor is fundamental for several reasons: (a) Development and similarly resolution of organ failure may take some time. Patients dying early may not have time to develop organ dysfunction/failure. (b) The time course of organ dysfunction/failure can be mult imodal during a complex clinical course, what is sometimes referred to as a \"multiple-hit\" scenario. (c) Time evaluation allows a greater understanding of the disease process as a natural process or under the influence of therapeutic interventions. The collection of data on a daily basis seems adequate. 3. The evaluation of organ dysfunction/failure should be based on a limited number of simple but objective variables that are easily and routinely measured in every institution. The collection of this information should not impose any intervention beyond what is routinely performed in every ICU. The variables used should as much as possible be independent of therapy, since therapeutic management may vary from one institution to another and even from one patient to another (Table 1). Until recently, none of the existing systems describing organ failure met these criteria, since they were based on categorial definitions or described organ failure as present or absent [5-7] . The ESICM organized a consensus meeting in Paris in October 1994 to create a so-called sepsis-related organ failure assessment (SOFA) score, to describe quantitatively and as objectively as possible the degree of organ dysfunction/failure over time in groups of patients or even in individual patients (Fig. 1). There are two major applications of such a SOFA score: 1. To improve our Understanding of the natural history of organ dysfunction/failure and the interrelation between the failure of the various organs.
8,538 citations
TL;DR: The SAPS II, based on a large international sample of patients, provides an estimate of the risk of death without having to specify a primary diagnosis, and is a starting point for future evaluation of the efficiency of intensive care units.
Abstract: Objective. —To develop and validate a new Simplified Acute Physiology Score, the SAPS II, from a large sample of surgical and medical patients, and to provide a method to convert the score to a probability of hospital mortality. Design and Setting. —The SAPS II and the probability of hospital mortality were developed and validated using data from consecutive admissions to 137 adult medical and/or surgical intensive care units in 12 countries. Patients. —The 13 152 patients were randomly divided into developmental (65%) and validation (35%) samples. Patients younger than 18 years, burn patients, coronary care patients, and cardiac surgery patients were excluded. Outcome Measure. —Vital status at hospital discharge. Results. —The SAPS II includes only 17 variables: 12 physiology variables, age, type of admission (scheduled surgical, unscheduled surgical, or medical), and three underlying disease variables (acquired immunodeficiency syndrome, metastatic cancer, and hematologic malignancy). Goodness-of-fit tests indicated that the model performed well in the developmental sample and validated well in an independent sample of patients (P=.883 andP=.104 in the developmental and validation samples, respectively). The area under the receiver operating characteristic curve was 0.88 in the developmental sample and 0.86 in the validation sample. Conclusion. —The SAPS II, based on a large international sample of patients, provides an estimate of the risk of death without having to specify a primary diagnosis. This is a starting point for future evaluation of the efficiency of intensive care units. (JAMA. 1993;270:2957-2963)
5,836 citations
TL;DR: Pressure support ventilation can assist spontaneous breathing and avoid diaphragmatic fatigue in patients demonstrating difficulties in weaning from the ventilator and clinical monitoring of sternocleidomastoid muscle activity allows the required level of pressure support to be determined to prevent fatigue.
Abstract: Persistent inability to tolerate discontinuation from mechanical ventilation is frequently encountered in patients recovering from acute respiratory failure. We studied the ability of inspiratory pressure support, a new mode of ventilatory assistance, to promote a nonfatiguing respiratory muscle activity in eight patients unsuccessful at weaning from mechanical ventilation. During spontaneous breathing, seven of the eight patients demonstrated electromyographic signs of incipient diaphragmatic fatigue. During ventilation with pressure support at increasing levels, the work of breathing gradually decreased (p less than 0.02) as well as the oxygen consumption of the respiratory muscles (p less than 0.01), and electrical signs suggestive of diaphragmatic fatigue were no longer present. In addition, intrinsic positive end-expiratory pressure was progressively reduced. For each patient an optimal level of pressure support was found (as much as 20 cm H2O), identified as the lowest level maintaining diaphragmatic activity without fatigue. Above this level, diaphragmatic activity was further reduced and untoward effects such as hyperinflation and apnea occurred. When electrical diaphragmatic fatigue occurred, the activity of the sternocleidomastoid muscle was markedly increased, whereas it was minimal when the optimal level was reached. We conclude that in patients demonstrating difficulties in weaning from the ventilator: (1) pressure support ventilation can assist spontaneous breathing and avoid diaphragmatic fatigue (pressure support allows adjustment of the work of each breath to provide an optimal muscle load); (2) clinical monitoring of sternocleidomastoid muscle activity allows the required level of pressure support to be determined to prevent fatigue.
517 citations
Additional excerpts
...a sufficient level of ventilatory support [3]....
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TL;DR: This Critical Care Perspective defines the phenomenon, henceforth referred to as ventilatorinduced diaphragmatic dysfunction (VIDD), as a loss of diaphRAGmatic force-generating capacity that is specifically related to the use of mechanical ventilation.
Abstract: Mechanical ventilation is a life-saving form of supportive therapy for respiratory failure. In addition to support of gas exchange, other potential benefits of mechanical ventilation include reversal of respiratory muscle fatigue, prevention of muscle fiber injury during sepsis, and restoration of blood flow to vital organs in shock states by preventing a “respiratory steal” phenomenon by intensely working respiratory muscles (1–3). However, mechanical ventilation is clearly a two-edged sword. It is also associated with major complications such as infection, barotrauma, cardiovascular compromise, tracheal injuries, oxygen toxicity, and ventilator-induced lung injury (4). In addition to the above well known complications of ventilatory support, a rapidly accumulating body of evidence suggests that mechanical ventilation, with its attendant diaphragm muscle inactivity and unloading, is an important cause of diaphragmatic dysfunction. For the purposes of this Critical Care Perspective, we define this phenomenon, henceforth referred to as ventilatorinduced diaphragmatic dysfunction (VIDD), as a loss of diaphragmatic force-generating capacity that is specifically related to the use of mechanical ventilation. The objectives of this Critical Care Perspective are as follows: (1) to review the existing evidence for VIDD, (2) to summarize the cellular changes in the diaphragm associated with the VIDD phenomenon, (3) to interpret these new findings in light of known effects of other forms of skeletal muscle disuse, and (4) to suggest future areas of research as well as potential therapeutic avenues.
492 citations
TL;DR: Low levels of PEEP may improve lung mechanics and reduce the effort required of mechanically ventilated patients with severe airflow obstruction, without substantially increasing the hazards of hyperinflation.
Abstract: Positive end-expiratory pressure (PEEP) has generally been withheld from the treatment of patients with chronic airflow obstruction (CAO), in view of the risk of hyperinflation and lack of documented benefit. We studied 10 mechanically ventilated patients with exacerbated CAO and air trapping to determine the impact of PEEP on lung mechanics, alveolar pressure, and the work of breathing. PEEP levels of 5 and 10 cmH2O were applied to patients whose end-expiratory alveolar pressures were documented to be positive when breathing against ambient pressure (the auto-PEEP effect). All patients were studied under two conditions: every breath machine assisted (AMV) and every breath machine controlled (paralyzed, CMV). PEEP improved expiratory resistance without substantially increasing peak static pressure. Inspiratory resistance remained unchanged. The difference between the end-expiratory values of alveolar and central airway pressure narrowed as PEEP increased. Adding PEEP improved the effective triggering sensitivity of the ventilator, diminished ventilatory drive, and reduced the mechanical work of breathing during the machine-assisted ventilatory cycle. Our results indicate that low levels of PEEP may improve lung mechanics and reduce the effort required of mechanically ventilated patients with severe airflow obstruction, without substantially increasing the hazards of hyperinflation.
427 citations