Background： Electrical impedance tomography （EIT） is a real-time bedside monitoring tool, which can reflect dynamic regional lung ventilation. The aim of the present study was to monitor regional gas distribution i...Background： Electrical impedance tomography （EIT） is a real-time bedside monitoring tool, which can reflect dynamic regional lung ventilation. The aim of the present study was to monitor regional gas distribution in patients with acute respiratory distress syndrome （ARDS） during positive-end-expiratory pressure （PEEP） titration using EIT. Methods： Eighteen ARDS patients under mechanical ventilation in Department of Critical Care Medicine of Peking Union Medical College Hospital from January to April in 2014 were included in this prospective observational study. After recruitment maneuvers （RMs）, decremental PEEP titration was performed from 20 cmH20 to 5 cmH20 in steps of 3 cmH20 every 5-10 min. Regional over-distension and recruitment were monitored with EIT. Results： After RMs, patient with arterial blood oxygen partial pressure （PaO2） ＋ carbon dioxide partial pressure （PaCO2） 〉400 mmHg with 100% of fractional inspired oxygen concentration were defined as RM responders. Thirteen ARDS patients was diagnosed as responders whose PaO2 ＋ PaCO2, were higher than nonresponders （419 ± 44 mmHg vs. 170 ±73 mmHg, P 〈 0.0001）. In responders, PEEP mainly increased-recruited pixels in dependent regions and over-distended pixels in nondependent regions. PEEP alleviated global inhomogeneity of tidal volume and end-expiratory lung volume. PEEP levels without significant alveolar derecruitment and over-distension were identified individually. Conclusions： After RMs, PEEP titration significantly affected regional gas distribution in lung, which could be monitored with EIT. EIT has the potential to optimize PEEP titration.展开更多
Objective:Tto investigate the effects of positive end-expiratory pressure(PEEP)ventilation on central venous pressure(CVP)and intraoperative blood loss in patients undergoing laparoscopic hepatectomy.Methods:46 cases ...Objective:Tto investigate the effects of positive end-expiratory pressure(PEEP)ventilation on central venous pressure(CVP)and intraoperative blood loss in patients undergoing laparoscopic hepatectomy.Methods:46 cases of patients undergoing laparoscopic hepatectomy,25 cases of male,female 21 cases,ASAⅠ~Ⅲlevel,were randomly divided into two groups.In group A tidal volume was set to 6 ml/kg(Predicted Body Weight,PBW)and PEEP was set to 0 cmH2O.The tidal volume of group B was set as group A,PEEP was set to 8 cmH2O.CVP,MAP,and Ppeak were recorded in the supine position after intubation(T0),supine position after pneumoperitoneal(T1),anti-trendelenberg position after pneumoperitoneal(T2),supine position after surgery(T3),and Ddyn was calculated.The amount of nitroglycerin and the amount of blood loss were recorded.Results:Compared with group A,the CVP of group B was significantly increased at T1 and T2(P<0.05).Compared to T2 with T1 in group A and group B,CVP was decreased significantly(P<0.05).At T3,Cdyn in group B was significantly higher than that in group A(P<0.05).The amount of nitroglycerin in group B was significantly higher than that in group A(P<0.05).There was no significant difference in intraoperative fluid rehydration and blood loss between the two groups(P>0.05).Conclusion:PEEP with 8cmH2O can improve Ddyn in patients undergoing laparoscopic hepatectomy,but increased CVP.It requires more use of controlled low central venous pressure techniques to reduce intraoperative blood loss.展开更多
The novel coronavirus,which was declared a pandemic by the World Health Organization in early 2020 has brought with itself major morbidity and mortality.It has increased hospital occupancy,heralded economic turmoil,an...The novel coronavirus,which was declared a pandemic by the World Health Organization in early 2020 has brought with itself major morbidity and mortality.It has increased hospital occupancy,heralded economic turmoil,and the rapid transmission and community spread have added to the burden of the virus.Most of the patients are admitted to the intensive care unit(ICU)for acute hypoxic respiratory failure often secondary to acute respiratory distress syndrome(ARDS).Based on the limited data available,there have been different opinions about the respiratory mechanics of the ARDS caused by coronavirus disease 2019(COVID-19).Our article provides an insight into COVID-19 pathophysiology and how it differs from typical ARDS.Based on these differences,our article explains the different approach to ventilation in COVID-19 ARDS compared to typical ARDS.We critically analyze the role of positive end-expiratory pressure(PEEP)and proning in the ICU patients.Through the limited data and clinical experience are available,we believe that early proning in COVID-19 patients improves oxygenation and optimal PEEP should be titrated based on individual lung compliance.展开更多
Driving pressure(ΔP)is a core therapeutic component of mechanical ventilation(MV).Varying levels ofΔP have been employed during MV depending on the type of underlying pathology and severity of injury.However,ΔP lev...Driving pressure(ΔP)is a core therapeutic component of mechanical ventilation(MV).Varying levels ofΔP have been employed during MV depending on the type of underlying pathology and severity of injury.However,ΔP levels have also been shown to closely impact hard endpoints such as mortality.Considering this,conducting an in-depth review ofΔP as a unique,outcome-impacting therapeutic modality is extremely important.There is a need to understand the subtleties involved in making sureΔP levels are optimized to enhance outcomes and minimize harm.We performed this narrative review to further explore the various uses ofΔP,the different parameters that can affect its use,and how outcomes vary in different patient populations at different pressure levels.To better utilizeΔP in MV-requiring patients,additional large-scale clinical studies are needed.展开更多
Background Patients with acute brain injury(ABI)are a peculiar population because ABI does not only affect the brain but also other organs such as the lungs,as theorized in brain–lung crosstalk models.ABI patients of...Background Patients with acute brain injury(ABI)are a peculiar population because ABI does not only affect the brain but also other organs such as the lungs,as theorized in brain–lung crosstalk models.ABI patients often require mechanical ventilation(MV)to avoid the complications of impaired respiratory function that can follow ABI;MV should be settled with meticulousness owing to its effects on the intracranial compartment,especially regarding positive end-expiratory pressure(PEEP).This scoping review aimed to(1)describe the physiological basis and mechanisms related to the effects of PEEP in ABI;(2)examine how clinical research is conducted on this topic;(3)identify methods for setting PEEP in ABI;and(4)investigate the impact of the application of PEEP in ABI on the outcome.Methods The five-stage paradigm devised by Peters et al.and expanded by Arksey and O'Malley,Levac et al.,and the Joanna Briggs Institute was used for methodology.We also adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)extension criteria.Inclusion criteria:we compiled all scientific data from peer-reviewed journals and studies that discussed the application of PEEP and its impact on intracranial pressure,cerebral perfusion pressure,and brain oxygenation in adult patients with ABI.Exclusion criteria:studies that only examined a pediatric patient group(those under the age of 18),experiments conducted solely on animals;studies without intracranial pressure and/or cerebral perfusion pressure determinations,and studies with incomplete information.Two authors searched and screened for inclusion in papers published up to July 2023 using the PubMed-indexed online database.Data were presented in narrative and tubular form.Results The initial search yielded 330 references on the application of PEEP in ABI,of which 36 met our inclusion criteria.PEEP has recognized beneficial effects on gas exchange,but it produces hemodynamic changes that should be predicted to avoid undesired consequences on cerebral blood flow and intracranial pressure.Moreover,the elastic properties of the lungs influence the transmission of the forces applied by MV over the brain so they should be taken into consideration.Currently,there are no specific tools that can predict the effect of PEEP on the brain,but there is an established need for a comprehensive monitoring approach for these patients,acknowledging the etiology of ABI and the measurable variables to personalize MV.Conclusion PEEP can be safely used in patients with ABI to improve gas exchange keeping in mind its potentially harmful effects,which can be predicted with adequate monitoring supported by bedside non-invasive neuromonitoring tools.展开更多
Background It is still controversial as to the implementation of higher positive end-expiratory pressure （PEEP） in patients with acute respiratory distress syndrome （ARDS）. This study was conducted to compare the ...Background It is still controversial as to the implementation of higher positive end-expiratory pressure （PEEP） in patients with acute respiratory distress syndrome （ARDS）. This study was conducted to compare the lower and higher PEEP in patients with ARDS ventilated with low tidal volume, to investigate the relationship between the recruited lung volume by higher PEEP and relevant independent variables and to provide a bedside estimate of the percentage of potentially recruitable lung by higher PEEP. Methods Twenty-four patients with ARDS were studied. A lung recruiting maneuver was performed, then each patient was ventilated with PEEP of 8 cmH20 for 4 hours and subsequently with PEEP of 16 cmH20 for 4 hours. At the end of each PEEP level period, gas exchange, hemodynamic data, lung mechanics, stress index ＂b＂ of the dynamic pressure-time curve, intrinsic PEEP and recruited volume by PEEP were measured. Results Fourteen patients were recruiters whose alveolar recruited volumes induced by PEEP 16 cmH20 were （425_＋65） ml and 10 patients were non-recruiters. Compared with the PEEP 8 cmH20 period, after the application of the PEEP 16 cmH20, the PaO2/FiO2 ratio and static lung compliance both remained unchanged in non-recruiters, whereas they increased significantly in recruiters. Changes in PaO2/FiO2 and static lung compliance after PEEP increase were independently associated with the alveolar recruitment. Analyzing the relationship between recruiting maneuver （RM）-induced change in end-expiratory lung volume and the alveolar recruitment induced by PEEP, we found a notable correlation. Conclusions The results of this study indicated that the potential for alveolar recruitment might vary among the ARDS population and the higher PEEP levels should be limited to recruiters. Improving in PaO2/FiO2, static lung compliance after PEEP increase and the shape of the pressure-time curve could be helpful for PEEP application.展开更多
Background High positive end-expiratory pressure （PEEP） and low tidal volume （VT） ventilation is thought to be a protective ventilation strategy. It is hypothesized that the stabilization of collapsible alveoli du...Background High positive end-expiratory pressure （PEEP） and low tidal volume （VT） ventilation is thought to be a protective ventilation strategy. It is hypothesized that the stabilization of collapsible alveoli during expiration contributes to lung protection. However, this hypothesis came from analysis of indirect indices like the analysis of the pressure-volume curve of the lung. The purpose of this study was to investigate isolated healthy and injured rat lungs by means of alveolar microscopy, in which combination of PEEP and VT is beneficial with respect to alveolar stability （I-E%）. Methods Alveolar stability was investigated in isolated, non-perfused mechanically ventilated rat lungs. Injured lungs were compared with normal lungs. For both groups three PEEP settings （5, 10, 20 cmH20） were combined with three VT settings （6, 10, 15 ml/kg） resulting in nine PEEP-VT combinations per group. Analysis was performed by alveolar microscopy. Results In normal lungs alveolar stability persisted in all PEEP-VT combinations （I-E% （3.2±11.0）%）. There was no significant difference using different settings （P 〉0.01）. In contrast, alveoli in injured lungs were extremely instable at PEEP levels of 5 cmH20 （mean I-E% 100%） and 10 cmH2O （mean I-E% （30.7±16.8）%）; only at a PEEP of 20 cmH20 were alveoli stabilized （mean I-E% of （0.2±9.3）%）. Conclusions In isolated healthy lungs alveolar stability is almost unaffected by different settings of PEEP and VT. In isolated injured lungs only a high PEEP level of 20 cmH2O resulted in stabilized alveoli whereas lower PEEP levels are associated with alveolar instability.展开更多
Background This study aimed to investigate the influence of positive end-expiratory pressure(PEEP)on the right ventricle(RV)of mechanical ventilation-assisted patients through echocardiography.Methods Seventy-six pati...Background This study aimed to investigate the influence of positive end-expiratory pressure(PEEP)on the right ventricle(RV)of mechanical ventilation-assisted patients through echocardiography.Methods Seventy-six patients assisted with mechanical ventilation were enrolled in this study.Positive end-expiratory pressure was upregulated by 4 cm H_(2)O to treat acute respiratory distress syndrome,wherein echocardiography was performed before and after this process.Hemodynamic data were also recorded.All variables were compared before and after PEEP upregulation.The effect of PEEP was also evaluated in patients with and without decreased static lung compliance(SLC).Results Positive end-expiratory pressure upregulation significantly affected the RV function.Remarkable differences were observed in the following:Tei index(P=0.027),pulmonary artery pressure(P=0.039),tricuspid annular plane systolic excursion(P=0.014),early wave/atrial wave(P=0.002),diaphragm excursion(P<0.001),inferior vena cava collapsing index(P<0.001),and SLC(P<0.001).There were no significant changes in heart rate,respiratory rate,central venous pressure,mean arterial pressure,and base excess(P>0.05).Furthermore,the cardiac output of the RV was not significantly affected.In patients with decreased SLC(n=41),there were more significant changes in diaphragm excursion(P<0.001),inferior vena cava collapse index(P=0.025),pulmonary artery pressure(P<0.001),and tricuspid annular plane systolic excursion(P=0.007)than in those without decreased SLC(n=35).Conclusion Positive end-expiratory pressure upregulation significantly affected the RV function of critically ill patients with acute respiratory distress syndrome,especially in those with decreased SLC.展开更多
Objective To compare the trigger delay and work of trigger between neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) in acute exacerbation of chronic obstructive pulmonary disease(AECO...Objective To compare the trigger delay and work of trigger between neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) in acute exacerbation of chronic obstructive pulmonary disease(AECOPD) patients with intrinsic positive end-expiratory pressure (PEEP) during mechanical ventilation.展开更多
Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasi...Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasible intervention that can be performed at the bedside in patients with ARDS. RMs are characterized by the application of airway pressure to increase transpulmonary pressure transiently. Once non-aerated lung units are reopened, improvements are observed in respiratory system mechanics, alveolar reaeration on computed tomography, and improvements in gas exchange(functional recruitment). However, the reopening process could lead to vascular compression, which can be associated with overinflation, and gas exchange may not improve as expected(anatomical recruitment). The purpose of this review was to discuss the effects of different RM strategies- sustained inflation, intermittent sighs, and stepwise increases of positive end-expiratory pressure(PEEP) and/or airway inspiratory pressure- on the following parameters: hemodynamics, oxygenation, barotrauma episodes, and lung recruitability through physiological variables and imaging techniques. RMs and PEEP titration are interdependent events for the success of ventilatory management. PEEP should be adjusted on the basis of respiratory system mechanics and oxygenation. Recent systematic reviews and meta-analyses suggest that RMs are associated with lower mortality in patients with ARDS. However, the optimal RM method(i.e., that providing the best balance of benefit and harm) and the effects of RMs on clinical outcome are still under discussion, and further evidence is needed.展开更多
Expiratory flow limitation(EFL), that is the inability of expiratory flow to increase in spite of an increase of the driving pressure, is a common and unrecognized occurrence during mechanical ventilation in a variety...Expiratory flow limitation(EFL), that is the inability of expiratory flow to increase in spite of an increase of the driving pressure, is a common and unrecognized occurrence during mechanical ventilation in a variety of intensive care unit conditions. Recent evidence suggests that the presence of EFL is associated with an increase in mortality, at least in acute respiratory distress syndrome(ARDS) patients, and in pulmonary complications in patients undergoing surgery. EFL is a major cause of intrinsic positive end-expiratory pressure(PEEPi), which in ARDS patients is heterogeneously distributed, with a consequent increase of ventilation/perfusion mismatch and reduction of arterial oxygenation. Airway collapse is frequently concomitant to the presence of EFL.When airways close and reopen during tidal ventilation, abnormally high stresses are generated that can damage the bronchiolar epithelium and uncouple small airways from the alveolar septa, possibly generating the small airways abnormalities detected at autopsy in ARDS. Finally, the high stresses and airway distortion generated downstream the choke points may contribute to parenchymal injury, but this possibility is still unproven. PEEP application can abolish EFL, decrease PEEPi heterogeneity, and limit recruitment/derecruitment.Whether increasing PEEP up to EFL disappearance is a useful criterion for PEEP titration can only be determined by future studies.展开更多
Several clinical and experimental studies have shown that lung injury occurs shortly after brain damage. The responsible mechanisms involve neurogenic pulmonary edema, inflammation, the harmful action of neurotransmit...Several clinical and experimental studies have shown that lung injury occurs shortly after brain damage. The responsible mechanisms involve neurogenic pulmonary edema, inflammation, the harmful action of neurotransmitters, or autonomic system dysfunction. Mechanical ventilation, an essential component of life support in brain-damaged patients(BD), may be an additional traumatic factor to the already injured or susceptible to injury lungs of these patients thus worsening lung injury, in case that non lung protective ventilator settings are applied. Measurement of respiratory mechanics in BD patients, as well as assessment of their evolution during mechanical ventilation, may lead to preclinical lung injury detection early enough, allowing thus the selection of the appropriate ventilator settings to avoid ventilatorinduced lung injury. The aim of this review is to explore the mechanical properties of the respiratory system in BD patients along with the underlying mechanisms, and to translate the evidence of animal and clinical studies into therapeutic implications regarding the mechanical ventilation of these critically ill patients.展开更多
The SRS TM Endoscopic Stapling System(Medigus,Tel Aviv,Israel) is a new tool capable of creating a totally endoscopic fundoplication,combined with an endoscope,endoscopic ultrasound and a surgical stapler.SRS TM endos...The SRS TM Endoscopic Stapling System(Medigus,Tel Aviv,Israel) is a new tool capable of creating a totally endoscopic fundoplication,combined with an endoscope,endoscopic ultrasound and a surgical stapler.SRS TM endoscopic stapling for gastro-esophageal reflux disease is a minimally invasive,outpatient procedure,which requires general anesthesia with positive-pressure ventilation.Keeping the patient on positive endexpiratory pressure(PEEP) may minimize the pressure gradient between the esophagus and the mediastinum,as well as help to prevent air from leaking around the screws and causing pneumomediastinum.In addition,in patients with hiatal hernia,higher PEEP levels may be required to increase intra-thoracic pressure and to force the stomach to slide into the abdomen for ease of endoscopy.We advise smoother emergence from anesthesia,taking precautions for retching,postoperative nausea and vomiting(PONV),while coughing and gagging during extubation and PONV may affect the success of the procedure.Total intravenous anesthesia with propofol and remifentanil seems to be a good choice for these reasons.展开更多
文摘Background： Electrical impedance tomography （EIT） is a real-time bedside monitoring tool, which can reflect dynamic regional lung ventilation. The aim of the present study was to monitor regional gas distribution in patients with acute respiratory distress syndrome （ARDS） during positive-end-expiratory pressure （PEEP） titration using EIT. Methods： Eighteen ARDS patients under mechanical ventilation in Department of Critical Care Medicine of Peking Union Medical College Hospital from January to April in 2014 were included in this prospective observational study. After recruitment maneuvers （RMs）, decremental PEEP titration was performed from 20 cmH20 to 5 cmH20 in steps of 3 cmH20 every 5-10 min. Regional over-distension and recruitment were monitored with EIT. Results： After RMs, patient with arterial blood oxygen partial pressure （PaO2） ＋ carbon dioxide partial pressure （PaCO2） 〉400 mmHg with 100% of fractional inspired oxygen concentration were defined as RM responders. Thirteen ARDS patients was diagnosed as responders whose PaO2 ＋ PaCO2, were higher than nonresponders （419 ± 44 mmHg vs. 170 ±73 mmHg, P 〈 0.0001）. In responders, PEEP mainly increased-recruited pixels in dependent regions and over-distended pixels in nondependent regions. PEEP alleviated global inhomogeneity of tidal volume and end-expiratory lung volume. PEEP levels without significant alveolar derecruitment and over-distension were identified individually. Conclusions： After RMs, PEEP titration significantly affected regional gas distribution in lung, which could be monitored with EIT. EIT has the potential to optimize PEEP titration.
基金Young Medical Professionals of Jiangsu Commission of Health(No.QNRC2016586).
文摘Objective:Tto investigate the effects of positive end-expiratory pressure(PEEP)ventilation on central venous pressure(CVP)and intraoperative blood loss in patients undergoing laparoscopic hepatectomy.Methods:46 cases of patients undergoing laparoscopic hepatectomy,25 cases of male,female 21 cases,ASAⅠ~Ⅲlevel,were randomly divided into two groups.In group A tidal volume was set to 6 ml/kg(Predicted Body Weight,PBW)and PEEP was set to 0 cmH2O.The tidal volume of group B was set as group A,PEEP was set to 8 cmH2O.CVP,MAP,and Ppeak were recorded in the supine position after intubation(T0),supine position after pneumoperitoneal(T1),anti-trendelenberg position after pneumoperitoneal(T2),supine position after surgery(T3),and Ddyn was calculated.The amount of nitroglycerin and the amount of blood loss were recorded.Results:Compared with group A,the CVP of group B was significantly increased at T1 and T2(P<0.05).Compared to T2 with T1 in group A and group B,CVP was decreased significantly(P<0.05).At T3,Cdyn in group B was significantly higher than that in group A(P<0.05).The amount of nitroglycerin in group B was significantly higher than that in group A(P<0.05).There was no significant difference in intraoperative fluid rehydration and blood loss between the two groups(P>0.05).Conclusion:PEEP with 8cmH2O can improve Ddyn in patients undergoing laparoscopic hepatectomy,but increased CVP.It requires more use of controlled low central venous pressure techniques to reduce intraoperative blood loss.
文摘The novel coronavirus,which was declared a pandemic by the World Health Organization in early 2020 has brought with itself major morbidity and mortality.It has increased hospital occupancy,heralded economic turmoil,and the rapid transmission and community spread have added to the burden of the virus.Most of the patients are admitted to the intensive care unit(ICU)for acute hypoxic respiratory failure often secondary to acute respiratory distress syndrome(ARDS).Based on the limited data available,there have been different opinions about the respiratory mechanics of the ARDS caused by coronavirus disease 2019(COVID-19).Our article provides an insight into COVID-19 pathophysiology and how it differs from typical ARDS.Based on these differences,our article explains the different approach to ventilation in COVID-19 ARDS compared to typical ARDS.We critically analyze the role of positive end-expiratory pressure(PEEP)and proning in the ICU patients.Through the limited data and clinical experience are available,we believe that early proning in COVID-19 patients improves oxygenation and optimal PEEP should be titrated based on individual lung compliance.
文摘Driving pressure(ΔP)is a core therapeutic component of mechanical ventilation(MV).Varying levels ofΔP have been employed during MV depending on the type of underlying pathology and severity of injury.However,ΔP levels have also been shown to closely impact hard endpoints such as mortality.Considering this,conducting an in-depth review ofΔP as a unique,outcome-impacting therapeutic modality is extremely important.There is a need to understand the subtleties involved in making sureΔP levels are optimized to enhance outcomes and minimize harm.We performed this narrative review to further explore the various uses ofΔP,the different parameters that can affect its use,and how outcomes vary in different patient populations at different pressure levels.To better utilizeΔP in MV-requiring patients,additional large-scale clinical studies are needed.
文摘Background Patients with acute brain injury(ABI)are a peculiar population because ABI does not only affect the brain but also other organs such as the lungs,as theorized in brain–lung crosstalk models.ABI patients often require mechanical ventilation(MV)to avoid the complications of impaired respiratory function that can follow ABI;MV should be settled with meticulousness owing to its effects on the intracranial compartment,especially regarding positive end-expiratory pressure(PEEP).This scoping review aimed to(1)describe the physiological basis and mechanisms related to the effects of PEEP in ABI;(2)examine how clinical research is conducted on this topic;(3)identify methods for setting PEEP in ABI;and(4)investigate the impact of the application of PEEP in ABI on the outcome.Methods The five-stage paradigm devised by Peters et al.and expanded by Arksey and O'Malley,Levac et al.,and the Joanna Briggs Institute was used for methodology.We also adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)extension criteria.Inclusion criteria:we compiled all scientific data from peer-reviewed journals and studies that discussed the application of PEEP and its impact on intracranial pressure,cerebral perfusion pressure,and brain oxygenation in adult patients with ABI.Exclusion criteria:studies that only examined a pediatric patient group(those under the age of 18),experiments conducted solely on animals;studies without intracranial pressure and/or cerebral perfusion pressure determinations,and studies with incomplete information.Two authors searched and screened for inclusion in papers published up to July 2023 using the PubMed-indexed online database.Data were presented in narrative and tubular form.Results The initial search yielded 330 references on the application of PEEP in ABI,of which 36 met our inclusion criteria.PEEP has recognized beneficial effects on gas exchange,but it produces hemodynamic changes that should be predicted to avoid undesired consequences on cerebral blood flow and intracranial pressure.Moreover,the elastic properties of the lungs influence the transmission of the forces applied by MV over the brain so they should be taken into consideration.Currently,there are no specific tools that can predict the effect of PEEP on the brain,but there is an established need for a comprehensive monitoring approach for these patients,acknowledging the etiology of ABI and the measurable variables to personalize MV.Conclusion PEEP can be safely used in patients with ABI to improve gas exchange keeping in mind its potentially harmful effects,which can be predicted with adequate monitoring supported by bedside non-invasive neuromonitoring tools.
文摘Background It is still controversial as to the implementation of higher positive end-expiratory pressure （PEEP） in patients with acute respiratory distress syndrome （ARDS）. This study was conducted to compare the lower and higher PEEP in patients with ARDS ventilated with low tidal volume, to investigate the relationship between the recruited lung volume by higher PEEP and relevant independent variables and to provide a bedside estimate of the percentage of potentially recruitable lung by higher PEEP. Methods Twenty-four patients with ARDS were studied. A lung recruiting maneuver was performed, then each patient was ventilated with PEEP of 8 cmH20 for 4 hours and subsequently with PEEP of 16 cmH20 for 4 hours. At the end of each PEEP level period, gas exchange, hemodynamic data, lung mechanics, stress index ＂b＂ of the dynamic pressure-time curve, intrinsic PEEP and recruited volume by PEEP were measured. Results Fourteen patients were recruiters whose alveolar recruited volumes induced by PEEP 16 cmH20 were （425_＋65） ml and 10 patients were non-recruiters. Compared with the PEEP 8 cmH20 period, after the application of the PEEP 16 cmH20, the PaO2/FiO2 ratio and static lung compliance both remained unchanged in non-recruiters, whereas they increased significantly in recruiters. Changes in PaO2/FiO2 and static lung compliance after PEEP increase were independently associated with the alveolar recruitment. Analyzing the relationship between recruiting maneuver （RM）-induced change in end-expiratory lung volume and the alveolar recruitment induced by PEEP, we found a notable correlation. Conclusions The results of this study indicated that the potential for alveolar recruitment might vary among the ARDS population and the higher PEEP levels should be limited to recruiters. Improving in PaO2/FiO2, static lung compliance after PEEP increase and the shape of the pressure-time curve could be helpful for PEEP application.
文摘Background High positive end-expiratory pressure （PEEP） and low tidal volume （VT） ventilation is thought to be a protective ventilation strategy. It is hypothesized that the stabilization of collapsible alveoli during expiration contributes to lung protection. However, this hypothesis came from analysis of indirect indices like the analysis of the pressure-volume curve of the lung. The purpose of this study was to investigate isolated healthy and injured rat lungs by means of alveolar microscopy, in which combination of PEEP and VT is beneficial with respect to alveolar stability （I-E%）. Methods Alveolar stability was investigated in isolated, non-perfused mechanically ventilated rat lungs. Injured lungs were compared with normal lungs. For both groups three PEEP settings （5, 10, 20 cmH20） were combined with three VT settings （6, 10, 15 ml/kg） resulting in nine PEEP-VT combinations per group. Analysis was performed by alveolar microscopy. Results In normal lungs alveolar stability persisted in all PEEP-VT combinations （I-E% （3.2±11.0）%）. There was no significant difference using different settings （P 〉0.01）. In contrast, alveoli in injured lungs were extremely instable at PEEP levels of 5 cmH20 （mean I-E% 100%） and 10 cmH2O （mean I-E% （30.7±16.8）%）; only at a PEEP of 20 cmH20 were alveoli stabilized （mean I-E% of （0.2±9.3）%）. Conclusions In isolated healthy lungs alveolar stability is almost unaffected by different settings of PEEP and VT. In isolated injured lungs only a high PEEP level of 20 cmH2O resulted in stabilized alveoli whereas lower PEEP levels are associated with alveolar instability.
文摘Background This study aimed to investigate the influence of positive end-expiratory pressure(PEEP)on the right ventricle(RV)of mechanical ventilation-assisted patients through echocardiography.Methods Seventy-six patients assisted with mechanical ventilation were enrolled in this study.Positive end-expiratory pressure was upregulated by 4 cm H_(2)O to treat acute respiratory distress syndrome,wherein echocardiography was performed before and after this process.Hemodynamic data were also recorded.All variables were compared before and after PEEP upregulation.The effect of PEEP was also evaluated in patients with and without decreased static lung compliance(SLC).Results Positive end-expiratory pressure upregulation significantly affected the RV function.Remarkable differences were observed in the following:Tei index(P=0.027),pulmonary artery pressure(P=0.039),tricuspid annular plane systolic excursion(P=0.014),early wave/atrial wave(P=0.002),diaphragm excursion(P<0.001),inferior vena cava collapsing index(P<0.001),and SLC(P<0.001).There were no significant changes in heart rate,respiratory rate,central venous pressure,mean arterial pressure,and base excess(P>0.05).Furthermore,the cardiac output of the RV was not significantly affected.In patients with decreased SLC(n=41),there were more significant changes in diaphragm excursion(P<0.001),inferior vena cava collapse index(P=0.025),pulmonary artery pressure(P<0.001),and tricuspid annular plane systolic excursion(P=0.007)than in those without decreased SLC(n=35).Conclusion Positive end-expiratory pressure upregulation significantly affected the RV function of critically ill patients with acute respiratory distress syndrome,especially in those with decreased SLC.
文摘Objective To compare the trigger delay and work of trigger between neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) in acute exacerbation of chronic obstructive pulmonary disease(AECOPD) patients with intrinsic positive end-expiratory pressure (PEEP) during mechanical ventilation.
基金Supported by Brazilian Council for Scientific and Technological Development(CNPq),Carlos Chagas Filho Rio de Janeiro State Research Foundation(FAPERJ),Department of Science and Technology(DECIT)/Brazilian Ministry of HealthCoordination for the Improvement of Higher Level Personnel(CAPES)
文摘Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasible intervention that can be performed at the bedside in patients with ARDS. RMs are characterized by the application of airway pressure to increase transpulmonary pressure transiently. Once non-aerated lung units are reopened, improvements are observed in respiratory system mechanics, alveolar reaeration on computed tomography, and improvements in gas exchange(functional recruitment). However, the reopening process could lead to vascular compression, which can be associated with overinflation, and gas exchange may not improve as expected(anatomical recruitment). The purpose of this review was to discuss the effects of different RM strategies- sustained inflation, intermittent sighs, and stepwise increases of positive end-expiratory pressure(PEEP) and/or airway inspiratory pressure- on the following parameters: hemodynamics, oxygenation, barotrauma episodes, and lung recruitability through physiological variables and imaging techniques. RMs and PEEP titration are interdependent events for the success of ventilatory management. PEEP should be adjusted on the basis of respiratory system mechanics and oxygenation. Recent systematic reviews and meta-analyses suggest that RMs are associated with lower mortality in patients with ARDS. However, the optimal RM method(i.e., that providing the best balance of benefit and harm) and the effects of RMs on clinical outcome are still under discussion, and further evidence is needed.
文摘Expiratory flow limitation(EFL), that is the inability of expiratory flow to increase in spite of an increase of the driving pressure, is a common and unrecognized occurrence during mechanical ventilation in a variety of intensive care unit conditions. Recent evidence suggests that the presence of EFL is associated with an increase in mortality, at least in acute respiratory distress syndrome(ARDS) patients, and in pulmonary complications in patients undergoing surgery. EFL is a major cause of intrinsic positive end-expiratory pressure(PEEPi), which in ARDS patients is heterogeneously distributed, with a consequent increase of ventilation/perfusion mismatch and reduction of arterial oxygenation. Airway collapse is frequently concomitant to the presence of EFL.When airways close and reopen during tidal ventilation, abnormally high stresses are generated that can damage the bronchiolar epithelium and uncouple small airways from the alveolar septa, possibly generating the small airways abnormalities detected at autopsy in ARDS. Finally, the high stresses and airway distortion generated downstream the choke points may contribute to parenchymal injury, but this possibility is still unproven. PEEP application can abolish EFL, decrease PEEPi heterogeneity, and limit recruitment/derecruitment.Whether increasing PEEP up to EFL disappearance is a useful criterion for PEEP titration can only be determined by future studies.
文摘Several clinical and experimental studies have shown that lung injury occurs shortly after brain damage. The responsible mechanisms involve neurogenic pulmonary edema, inflammation, the harmful action of neurotransmitters, or autonomic system dysfunction. Mechanical ventilation, an essential component of life support in brain-damaged patients(BD), may be an additional traumatic factor to the already injured or susceptible to injury lungs of these patients thus worsening lung injury, in case that non lung protective ventilator settings are applied. Measurement of respiratory mechanics in BD patients, as well as assessment of their evolution during mechanical ventilation, may lead to preclinical lung injury detection early enough, allowing thus the selection of the appropriate ventilator settings to avoid ventilatorinduced lung injury. The aim of this review is to explore the mechanical properties of the respiratory system in BD patients along with the underlying mechanisms, and to translate the evidence of animal and clinical studies into therapeutic implications regarding the mechanical ventilation of these critically ill patients.
文摘The SRS TM Endoscopic Stapling System(Medigus,Tel Aviv,Israel) is a new tool capable of creating a totally endoscopic fundoplication,combined with an endoscope,endoscopic ultrasound and a surgical stapler.SRS TM endoscopic stapling for gastro-esophageal reflux disease is a minimally invasive,outpatient procedure,which requires general anesthesia with positive-pressure ventilation.Keeping the patient on positive endexpiratory pressure(PEEP) may minimize the pressure gradient between the esophagus and the mediastinum,as well as help to prevent air from leaking around the screws and causing pneumomediastinum.In addition,in patients with hiatal hernia,higher PEEP levels may be required to increase intra-thoracic pressure and to force the stomach to slide into the abdomen for ease of endoscopy.We advise smoother emergence from anesthesia,taking precautions for retching,postoperative nausea and vomiting(PONV),while coughing and gagging during extubation and PONV may affect the success of the procedure.Total intravenous anesthesia with propofol and remifentanil seems to be a good choice for these reasons.
