Complications of acute respiratory failure

Comparative evaluation of three total full-face masks for delivering Non-Invasive Positive Pressure Ventilation (NPPV): a bench study

Historically, the oro-nasal mask has been the preferred interface to deliver Non-Invasive Positive Pressure Ventilation (NPPV) in critically ill patients. To overcome the problems related to air leaks and discomfort, Total Full-face masks have been designed. No study has comparatively evaluated the performance of the total Full-face masks available.The aim of this bench study was to evaluate the influence of three largely diffuse models of total Full -face masks on patient-ventilator synchrony and performance during pressure support ventilation. NPPV was applied to a mannequin, connected to an active test lung through three largely diffuse Full-face masks: Dimar Full-face mask (DFFM), Performax Full-face mask (RFFM) and Pulmodyne Full-face mask (PFFM).The performance analysis showed that the ΔPtrigger was significantly lower with PFFM (p < 0.05) at 20 breaths/min (RRsim) at both pressure support (iPS) levels applied, while, at RRsim 30, DFFM had the longest ΔPtrigger compared to the other 2 total full face masks (p < 0.05). At all ventilator settings, the PTP200 was significantly shorter with DFFM than with the other two total full-face masks (p < 0.05). In terms of PTP500 ideal index (%), we did not observe significant differences between the interfaces tested.The PFFM demonstrated the best performance and synchrony at low respiratory rates, but when the respiratory rate increased, no difference between all tested total full-face masks was reported.

The success of non-invasive mechanical ventilation in lung cancer patients with respiratory failure

INTRODUCTION AND AIM

Despite the improvement in survival among patients with lung cancer as a result of the development of novel treatment options, acute respiratory failure (ARF), which may occur because of the disease itself, comorbidities or complications in treatment may be life threatening. The most commonly utilised treatment option in cancer patients with ARF is invasive mechanical ventilation (IMV). The prognosis of lung cancer patients admitted to the intensive care unit is poor. The use of non-invasive mechanical ventilation (NIMV) in the setting of ARF not only supports the respiratory muscles and facilitates alveolar ventilation and airway patency, but also reduces the risk of serious complications of IMV, such as ventilator-associated pneumonia. NIMV treatment in the event of respiratory failure has been associated with a high rate of mortality in recently diagnosed or progressive lung cancer with organ failure. However, studies in this regard are limited, and the role of NIMV has yet to be investigated in patients in hospital wards. Accordingly, the present study investigates retrospectively the success of NIMV among patients with lung cancer (including all stages and histopathological types) in a hospital ward setting and the influential factors.

MATERIAL AND METHOD

The data of 42 patients with lung cancer and respiratory failure who were admitted to the palliative care service and received NIMV between 2014 and 2018 were reviewed retrospectively. Demographic features, comorbidities, respiratory failure types, rate of withdrawal from NIMV, frequencies of tracheostomy and intubation, bacteriologic examination of the airway samples, rate of discharge from hospital and any history of NIMV/USOT use at home were recorded. NIMV success was defined as the discharge of the patient from the hospital, with or without a respiratory support device. The primary end-point of the study was NIMV success, while the secondary end-point was NIMV success with respect to the underlying diagnosis and respiratory failure type.

RESULTS

A total of 42 patients (38 males and 4 females) were included in the study, with a mean age of 67.4 ± 9.5 years. The rate of discharge from hospital was 71% across the entire study population, among which, 13 (31%) were discharged with USOT and 16 (38.1%) with NIMV. Among the 12 patients under palliative supportive treatment, 8 were discharged from the hospital. The success rates of NIMV in the respiratory failure aetiological subgroups were: 66% (12 patients) in the pneumonia subgroup and 71.4% (15 patients) in the COPD subgroup. The difference between these subgroups was not significant (P = .841). The success rate of NIMV in the hypercapnic and hypoxaemic respiratory failure subgroups was 72.7% (24 patients) and 66.6% (6 patients), respectively. There were no significant differences between the type of respiratory failure subgroups (P = .667). The success rate of NIMV was similar in patients with a positive airway sample microbiology (71.4%, n = 14) and those with no growth identified in the culture (70.3%, n = 28) (P = .834).

CONCLUSION

In lung cancer patients with no contraindication, NIMV can be used to reduce or postpone the need for ICU admission, independent of disease stage, cellular type and underlying cause.

Dexamethasone and transdehydroandrosterone significantly reduce pulmonary epithelial cell injuries associated with mechanical ventilation

Many patients who suffer from pulmonary diseases cannot inflate their lungs normally, as they need mechanical ventilation (MV) to assist them. The stress associated with MV can damage the delicate epithelium in small airways and alveoli, which can cause complications resulting in ventilation-induced lung injuries (VILIs) in many cases, especially in patients with acute respiratory distress syndrome (ARDS). Therefore, efforts were directed to develop safe modes for MV. In our work, we propose a different approach to decrease injuries of epithelial cells (EpCs) upon MV. We alter EpCs' cytoskeletal structure to increase their survival rate during airway reopening conditions associated with MV. We tested two anti-inflammatory drugs dexamethasone (DEX) and transdehydroandrosterone (DHEA) to alter the cytoskeleton. Cultured rat L2 alveolar EpCs were exposed to airway reopening conditions using a parallel-plate perfusion chamber. Cells were exposed to a single bubble propagation to simulate stresses associated with mechanical ventilation in both control and study groups. Cellular injury and cytoskeleton reorganization were assessed via fluorescence microscopy, whereas cell topography was studied via atomic force microscopy (AFM). Our results indicate that culturing cells in media, DEX solution, or DHEA solution did not lead to cell death (static cultures). Bubble flows caused significant cell injury. Preexposure to DEX or DHEA decreased cell death significantly. The AFM verified alteration of cell mechanics due to actin fiber depolymerization. These results suggest potential beneficial effects of DEX and DHEA for ARDS treatment for patients with COVID-19. They are also critical for VILIs and applicable to future clinical studies.NEW & NOTEWORTHY Preexposure of cultured cells to either dexamethasone or transdehydroandrosterone significantly decreases cellular injuries associated with mechanical ventilation due to their ability to alter the cell mechanics. This is an alternative protective method against VILIs instead of common methods that rely on modification of mechanical ventilator modes.

The predictive value of brain natriuretic peptide or N-terminal pro-brain natriuretic peptide for weaning outcome in mechanical ventilation patients: Evidence from SROC

OBJECTIVE

Mechanical ventilation is an important treatment for critically ill patients. Physicians generally perform a spontaneous breathing trial (SBT) to determine whether the patients can be weaned from mechanical ventilation, but almost 17% of the patients who pass the SBT still require respiratory support. Cardiac dysfunction is an important cause of weaning failure. The use of brain natriuretic peptide or N-terminal pro-BNP is a simple method to assess cardiac function. We performed a systematic review of investigations of brain natriuretic peptide or N-terminal pro-BNP as predictors of weaning from mechanical ventilation.

DATA SOURCES

PubMed (1950 to December 2020), Cochrane, and Embase (1974 to December 2020), and some Chinese databases for additional articles (China Biology Medicine (CBM), China Science and Technology Journal Database (CSTJ), and Wanfang Data and China National Knowledge Infrastructure (CNKI)).

STUDY SELECTION

We systematically searched observation studies investigating the predictive value of brain natriuretic peptide or N-terminal pro-brain natriuretic peptide in weaning outcome of patients with mechanical ventilation.

DATA EXTRACTION

Two independent reviewers extracted data. The differences are resolved through consultation.

DATA SYNTHESIS

We included 18 articles with 1416 patients and extracted six index tests with pooled sensitivity and specificity for each index test. For the BNP change rate predicting weaning success, the pooled sensitivity was 89% (83%-94%) and the pooled specificity was 82% (72%-89%) with the highest pooled AUC of 0.9511.

CONCLUSIONS

The brain natriuretic peptide change rate is a reliable predictor of weaning outcome from mechanical ventilation.

Protocolised non-invasive compared with invasive weaning from mechanical ventilation for adults in intensive care: the Breathe RCT

BACKGROUND

Invasive mechanical ventilation (IMV) is a life-saving intervention. Following resolution of the condition that necessitated IMV, a spontaneous breathing trial (SBT) is used to determine patient readiness for IMV discontinuation. In patients who fail one or more SBTs, there is uncertainty as to the optimum management strategy.

OBJECTIVE

To evaluate the clinical effectiveness and cost-effectiveness of using non-invasive ventilation (NIV) as an intermediate step in the protocolised weaning of patients from IMV.

DESIGN

Pragmatic, open-label, parallel-group randomised controlled trial, with cost-effectiveness analysis.

SETTING

A total of 51 critical care units across the UK.

PARTICIPANTS

Adult intensive care patients who had received IMV for at least 48 hours, who were categorised as ready to wean from ventilation, and who failed a SBT.

INTERVENTIONS

Control group (invasive weaning): patients continued to receive IMV with daily SBTs. A weaning protocol was used to wean pressure support based on the patient's condition. Intervention group (non-invasive weaning): patients were extubated to NIV. A weaning protocol was used to wean inspiratory positive airway pressure, based on the patient's condition.

MAIN OUTCOME MEASURES

The primary outcome measure was time to liberation from ventilation. Secondary outcome measures included mortality, duration of IMV, proportion of patients receiving antibiotics for a presumed respiratory infection and health-related quality of life.

RESULTS

A total of 364 patients (invasive weaning, n = 182; non-invasive weaning, n = 182) were randomised. Groups were well matched at baseline. There was no difference between the invasive weaning and non-invasive weaning groups in median time to liberation from ventilation {invasive weaning 108 hours [interquartile range (IQR) 57-351 hours] vs. non-invasive weaning 104.3 hours [IQR 34.5-297 hours]; hazard ratio 1.1, 95% confidence interval [CI] 0.89 to 1.39; p = 0.352}. There was also no difference in mortality between groups at any time point. Patients in the non-invasive weaning group had fewer IMV days [invasive weaning 4 days (IQR 2-11 days) vs. non-invasive weaning 1 day (IQR 0-7 days); adjusted mean difference -3.1 days, 95% CI -5.75 to -0.51 days]. In addition, fewer non-invasive weaning patients required antibiotics for a respiratory infection [odds ratio (OR) 0.60, 95% CI 0.41 to 1.00; p = 0.048]. A higher proportion of non-invasive weaning patients required reintubation than those in the invasive weaning group (OR 2.00, 95% CI 1.27 to 3.24). The within-trial economic evaluation showed that NIV was associated with a lower net cost and a higher net effect, and was dominant in health economic terms. The probability that NIV was cost-effective was estimated at 0.58 at a cost-effectiveness threshold of £20,000 per quality-adjusted life-year.

CONCLUSIONS

A protocolised non-invasive weaning strategy did not reduce time to liberation from ventilation. However, patients who underwent non-invasive weaning had fewer days requiring IMV and required fewer antibiotics for respiratory infections.

FUTURE WORK

In patients who fail a SBT, which factors predict an adverse outcome (reintubation, tracheostomy, death) if extubated and weaned using NIV?

TRIAL REGISTRATION

Current Controlled Trials ISRCTN15635197.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 48. See the NIHR Journals Library website for further project information.

Effects of noninvasive ventilation in amyotrophic lateral sclerosis: The complication of bulbar impairment

Amyotrophic lateral sclerosis is a neurodegenerative illness that causes gradual loss of muscle function. Patients eventually develop bulbar impairment, requiring extensive respiratory support. Noninvasive ventilation (NIV) has gained attention as an easily accessible method with promising benefits. We conducted this systematic review to outline the therapeutic effects of NIV, add to previous publications discussing this topic by providing updates on newly completed and ongoing studies, and identify limitations that must be addressed in future trials. A search of PubMed and Cochran for relevant primary studies yielded 26 publications. Studies indicate NIV use is associated with improvements in quality of life, regardless of the severity of bulbar impairment. However, NIV’s benefits on survival were limited to patients with less bulbar impairment. In addition, our review found several limitations that undermine the efforts to establish a definitive treatment regimen. Future studies will need to address these problems in order to provide patients with better respiratory care.

Frequency of Screening and SBT Technique Trial - North American Weaning Collaboration (FAST-NAWC): a protocol for a multicenter, factorial randomized trial

RATIONALE

In critically ill patients receiving invasive mechanical ventilation (MV), research supports the use of daily screening to identify patients who are ready to undergo a spontaneous breathing trial (SBT) followed by conduct of an SBT. However, once daily (OD) screening is poorly aligned with the continuous care provided in most intensive care units (ICUs) and the best SBT technique for clinicians to use remains controversial.

OBJECTIVES

To identify the optimal screening frequency and SBT technique to wean critically ill adults in the ICU.

METHODS

We aim to conduct a multicenter, factorial design randomized controlled trial with concealed allocation, comparing the effect of both screening frequency (once versus at least twice daily [ALTD]) and SBT technique (Pressure Support [PS] + Positive End-Expiratory Pressure [PEEP] vs T-piece) on the time to successful extubation (primary outcome) in 760 critically ill adults who are invasively ventilated for at least 24 h in 20 North American ICUs. In the OD arm, respiratory therapists (RTs) will screen study patients between 06:00 and 08:00 h. In the ALTD arm, patients will be screened at least twice daily between 06:00 and 08:00 h and between 13:00 and 15:00 h with additional screens permitted at the clinician's discretion. When the SBT screen is passed, an SBT will be conducted using the assigned technique (PS + PEEP or T-piece). We will follow patients until successful extubation, death, ICU discharge, or until day 60 after randomization. We will contact patients or their surrogates six months after randomization to assess health-related quality of life and functional status.

RELEVANCE

The around-the-clock availability of RTs in North American ICUs presents an important opportunity to identify the optimal SBT screening frequency and SBT technique to minimize patients' exposure to invasive ventilation and ventilator-related complications.

TRIAL REGISTRATION

Clinical Trials.gov, NCT02399267 . Registered on Nov 21, 2016 first registered.

Variation in the practice of discontinuing mechanical ventilation in critically ill adults: study protocol for an international prospective observational study

INTRODUCTION

Research supports the use of specific strategies to discontinue mechanical ventilation (MV) in critically ill patients. Little is known about how clinicians actually wean and discontinue MV in practice or the association between different discontinuation strategies and outcomes. The primary objective of this study is to describe international practices in the use of (1) daily screening for readiness to discontinue MV, (2) modes of MV used before initial discontinuation attempts, (3) weaning and spontaneous breathing trial (SBT) protocols, (4) SBT techniques and (5) sedation and mobilisation practices to facilitate weaning and discontinuation. The secondary objectives are to identify patient characteristics and time-dependent factors associated with use of selected strategies, investigate associations between SBT outcome (failure vs success) and outcomes, explore differences between patients who undergo an SBT early versus later in their intensive care unit (ICU) stay, and investigate the associations between different SBT techniques and humidification strategies on outcomes.

METHODS AND ANALYSIS

We will conduct an international, prospective, observational study of MV discontinuation practices among critically ill adults who receive invasive MV for at least 24 hours at approximately 150 ICUs in six geographic regions (Canada, USA, UK, Europe, India and Australia/New Zealand). Research personnel at participating ICUs will collect demographic data, data to characterise the initial strategy or event that facilitated discontinuation of MV (direct extubation, direct tracheostomy, initial successful SBT, initial failed SBT or death before any attempt could be made), clinical outcomes and site information. We aim to collect data on at least 10 non-death discontinuation events in each ICU (at least 1500 non-death discontinuation events).

ETHICS AND DISSEMINATION

This study received Research Ethics Approval from St. Michael's Hospital (11-024) Research ethics approval will be sought from all participating sites. The results will be disseminated through publications in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03955874.

Factors Affecting Cost of Patients with Severe Community-Acquired Pneumonia in Intensive Care Unit

OBJECTIVES

The aim of this study is to investigate the factors affecting cost in patients with severe community-acquired pneumonia (CAP) who were admitted to the intensive care unit (ICU).

MATERIALS AND METHODS

This retrospective cohort study was conducted between January 2013 and December 2016. A total of 291 sequential patients with severe CAP were included in the study. Patients' demographic and clinical data; the need for invasive mechanical ventilation or non-invasive mechanical ventilation; intensive care severity (ICU) scores, including Acute Physiology and Chronic Health Evaluation (APACHE II), Sepsis-related Organ Failure Assessment, Quick SOFA, pneumonia severity index (PSI); and Confusion, Urea, Respiratory Rate, and Blood Pressure-65 (CURB-65) scores were obtained from medical records and recorded for all cases.

RESULTS

The mean age of 291 patients was 68.4±16.8 years, and 61% were female. The median length of ICU stay was 7 days. Forty-six percent of patients had chronic obstructive pulmonary disease (COPD), and 42% had hypertension. The mean cost of each hospitalization was US$ 2722 (TL 5578). The highest cost was found in the group of patients aged 50-59 years, and the lowest cost was found in the patients aged <50 years. A statistically significant relationship was found between ICU severity scores and health cost. The cost of patients in PSI class V, APACHE II (>20 points), and CURB-65 score were higher. The presence of COPD, atrial fibrillation, congestive heart failure, hypoalbuminemia, mental state deterioration, in-hospital mortality, severe sepsis, septic shock, mechanical ventilation requirement, and haloperidol and vasopressor usage were associated with higher cost, while the use of florokinolon was associated with lower cost.

CONCLUSION

The presence of certain comorbidities and high disease severity in patients with severe CAP hospitalized in ICU increase the cost of inpatient treatment. The need for mechanical ventilation during treatment and the presence of sepsis/septic shock are additional factors that increase the cost.

Non-invasive ventilation in cardiogenic pulmonary edema

Cardiogenic pulmonary edema (CPE) is among the most common causes of acute respiratory failure (ARF) in the acute care setting and often requires ventilatory assistance. In patients with ARF due to CPE, use of non-invasive positive airway pressure can decrease the systemic venous return and the left ventricular (LV) afterload, thus reducing LV filling pressure and limiting pulmonary edema. In these patients, either non-invasive ventilation (NIV) or continuous positive airway pressure (CPAP) can improve vital signs and physiological parameters, decreasing the need for endotracheal intubation (ETI) and hospital mortality when compared to conventional oxygen therapy. Results on the use of NIV or CPAP in patients with CPE prior to hospitalization are not homogeneous among studies, hampering any conclusive recommendation regarding their role in the pre-hospital setting.

Prognostic factors of noninvasive mechanical ventilation in lung cancer patients with acute respiratory failure

Introduction

Few studies have reported outcomes of lung cancer patients with acute respiratory failure (RF) using noninvasive positive pressure ventilation (NIPPV). The aim of this study was to investigate the prognostic factors in these patients.

Materials and methods

This retrospective observational study included all hospitalized lung cancer patients who received NIPPV for acute RF. It was conducted at a tertiary medical center in Taiwan from 2005 to 2010. The primary outcome was all cause mortality at 28 days after the initiation of NIPPV. Secondary outcomes included all-cause in-hospital mortality, weaning from NIPPV, intubation rate, tracheostomy rate, duration of NIPPV, hospital stay and intensive care unit stay.

Results

The all-cause mortality rate at day 28 of the enrolled 58 patients was 39.66%. The 90-day and 1-year mortality rates were 63.79% and 86.21%, respectively. NIPPV as the first line therapy for RF had higher 28-day mortality rate than it used for post-extubation RF (57.6% versus 16.0%, p<0.05). Independent predictors of mortality at 28 days were progressive disease or newly diagnosed lung cancer (OR 14.02 95% CI 1.03–191.59, p = 0.048), combined with other organ failure (OR 18.07 95% CI 1.87–172.7, p = 0.012), and NIPPV as the first line therapy for RF (OR 35.37 95% CI 3.30–378.68, p = 0.003).

Conclusion

Lung cancer patients using NIPPV with progressive or newly diagnosed cancer disease, combined with other organ failure, or NIPPV as the first line therapy for respiratory failure have a poor outcome.

Predictive factors of in-hospital mortality in ventilated intensive care unit: A prospective cohort study

Although it is clear that ventilated intensive care unit (ICU) patients have worse outcomes than those who are not, information about the risk factors of in-hospital mortality remains important for medical groups to target interventions for these patients.The purpose of this study was to identify predictive factors of in-hospital mortality in ventilated ICU patients with an admission diagnosis of acute respiratory failure.We conducted a prospective cohort study in 3 medical ICUs in a 3600-bed university hospital. Consecutive patients with acute respiratory failure who received mechanical ventilation (MV) for at least 96 hours without evidence of pre-existing neuromuscular diseases were followed until discharge. Upon inclusion, the following parameters were collected or evaluated: demographics, clinical history (admission body mass index [BMI], etiology of acute respiratory failure, comorbidity, Charlson comorbidity index, laboratory data), Acute Physiology and Chronic Health Evaluation (APACHE) II, and right and left quadriceps femoris muscle force. The days of MV before extubation, ICU length of stay, survival status at discharge, and hospital length of stay were recorded from the hospital discharge summary. The primary endpoint was in-hospital mortality.In all, 113 patients (65.49% males) were recruited with a mean age of 69.78 years and mean APACHE II score of 22.63. The mean ICU length of stay was 14.88 ± 9.79 days. Overall in-hospital mortality was 25.66% (29 out of 113 patients). Multivariate analysis showed that the essential factors associated with increased in-hospital mortality were lower BMI (P = .013), and lower scores on the right or left quadriceps femoris muscle force (P = .002 and .010, respectively).Our study suggests that lower BMI and lower scores on lower limb muscle force may be associated with increased in-hospital mortality in ventilated ICU patients.

Can high-flow nasal cannula reduce the rate of reintubation in adult patients after extubation? A meta-analysis

BACKGROUND

The effects of high flow nasal cannula (HFNC) on adult patients after extubation remain controversial. We aimed to further determine the effectiveness of HFNC in comparison to noninvasive positive pressure ventilation (NIPPV) and conventional oxygen therapy (COT).

METHODS

The Pubmed, Embase, Medline, Cochrane Central Register of Controlled Trails (CENTRAL) as well as the Information Sciences Institute (ISI) Web of Science were searched for all the controlled study comparing HFNC with NIPPV and COT in adult patients after extubation. The primary outcome was rate of reintubation and the secondary outcomes were intensive care unit (ICU) mortality and length of ICU stay (ICU LOS).

RESULTS

Eight trials with a total of 2936 patients were pooled in our final studies. No significant heterogeneity was found in outcome measures. Compared with COT, HFNC was associated with lower rate of reintubation (Z = 2.97, P = 0.003), and the same result was found in the comparison between HFNC and NIPPV (Z = 0.87, P = 0.38). As for the ICU mortality and ICU LOS, we did not find any advantage of HFNC over COT or NIPPV.

CONCLUSIONS

In patients after extubation, HFNC is a reliable alternative of NIPPV to reduce rate of reintubation compared with COT.

Controversies in Weaning from Mechanical Ventilation

Invasive mechanical ventilation can successfully support the patient with acute respiratory failure, but it is associated with considerable risks. Numerous complications of invasive mechanical ventilation have been identified, and these may contribute to increased mortality. Therefore after clinical improvement has occurred, considerable emphasis is placed on expeditiously freeing the patient from the ventilator. This process of getting a patient off mechanical ventilation has been variably termed weaning, liberation, or discontinuation (terms which may be used interchangeably), and can be further divided into “readiness testing” and “progressive withdrawal.” Over the last decade, new developments in our understanding of the process of weaning have provided investigators with the tools to address a number of key questions: How should readiness for weaning (and trials of spontaneous breathing) be determined? What is the role of weaning parameters in deciding when to initiate the weaning process? What is the best mode for conducting a spontaneous breathing trial and how should the patient be monitored? What are the mechanisms for weaning (and spontaneous breathing trial) failure? What is the best technique to facilitate progressive withdrawal? What other factors can facilitate liberation from mechanical ventilation? What are the risks of extubation failure and how can extubation outcome best be predicted? What is the role for protocols in facilitating weaning from mechanical ventilation?.

Noninvasive Ventilation

Noninvasive ventilation (NIV) has assumed a prominent role in the treatment of patients with both hypoxemic and hypercapnic acute respiratory failure (ARF). The main theoretic advantages of NIV include avoiding side effects and complications associated with endotracheal intubation, improving patient comfort, and preserving airway defense mechanisms. Factors that affect the success of NIV in patients with ARF are clinicians' expertise, selection of patient, choice of interface, selection of ventilator setting, proper monitoring, and patient motivation. Advances in the understanding of the physiologic aspects of using NIV through different interfaces and ventilator modalities have improved patient-machine interaction, thus enhancing favorable NIV outcome.

CT and Chest Radiography in the Evaluation of Adult Respiratory Distress Syndrome

CT is seldom employed in adult respiratory distress syndrome (ARDS), mostly due to problems in transporting and monitoring these severely ill patients. We reviewed the findings of 74 ARDS patients who underwent chest CT. Lung opacities were bilateral in almost all patients and dependent in most cases (86%). The opacities were patchy (42%), homogeneous (23%), ground glass (8%) or mixed (27%). Opacities prevailed in basal regions (68%) compared to hilar and apical ones. Air bronchograms were frequently seen in areas of consolidation (89%). In contrast with previous reports, pleural effusion was a frequent finding (50%) that did not worsen prognosis. Often loculated pneumothorax (32%) was mostly anteromedial. Ineffective position of thoracostomy tubes was detected at CT in 13/20 patients. Pulmonary air cysts (30%>), always multiple and mostly bilateral, were associated with a higher mortality (55%) than that of the whole study group (35%). Compared to chest radiographs, CT often yielded additional information (66%), with direct influence on patient treatment in 22% of cases.

Multiple System Organ Failure in the Adult Respiratory Distress Syndrome

Recently completed studies suggest that patients with the adult respiratory distress syndrome (ARDS) manifest early evidence of multiple-site endothelial injury. Ex trapulmonary disease is usually the cause of death in these patients. Furthermore, prognosis in individual cases of ARDS is strongly influenced by specific organ failures (e.g., hepatic and renal failure). The mechanisms by which ARDS and extrapulmonary organ system fail ure interact, however, are poorly delineated. We ad dress three aspects of the multisystemic nature of ARDS. First, we analyze evidence that suggests ARDS is a mul tisystem disorder fron the outset, involving panendothe lial injury mediated by cellular interactions and humoral substances that act similarly at many vascular target sites. Second, we discuss the role of three extrapulmo nary organs in the modulation of ARDS: the liver, the gastrointestinal mucosa, and the kidneys. Third, we ad dress the unifying hypothesis that uncontrolled ongoing inflammation, which is often but not always caused by infection, is the essential link between ARDS and its progression to multiple system organ failure.

Use of noninvasive ventilation at the pulmonary infection control window for acute respiratory failure in AECOPD patients: A systematic review and meta-analysis based on GRADE approach

The aim of the study was to comprehensively examine the efficacy and safety of noninvasive ventilation used at the pulmonary infection control (PIC) window for acute respiratory failure (ARF) in patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD).Seven electronic databases and relevant resources were searched to identify randomized controlled trials (RCTs) comparing patients using noninvasive ventilation at PIC window with those continuing receiving invasive ventilation. Retrieved citations were screened, risk of bias was assessed, and data were extracted by 2 independent review authors. Overall effect sizes were synthesized by using meta-analyses. Quality of evidence was rated by using Grading of Recommendations, Assessment, Development and Evaluation approach.A total of 17 trials involving 959 participants were included for this review. Compared with continuous invasive ventilation, noninvasive ventilation used at PIC window significantly reduced mortality, ventilator-associated pneumonia, weaning failures, reintubations, duration of invasive ventilation, total duration of mechanical ventilation, length of stay (LOS) in intensive care unit, and LOS in hospital as well as hospital costs. Of these, mortality significantly decreased (risk ratio = 0.27, 95% confidence interval: 0.17-0.42, P < 0.001) without significant heterogeneity (I = 0%, P = 0.99). Quality of evidence regarding the 9 outcomes across the included studies was rated from moderate to low.Use of noninvasive ventilation at PIC window showed beneficial effects across identified trials for ARF in AECOPD patients. Considering the absence of high quality of available evidence and the uncertainty of long-term effect of this intervention, a weak recommendation for clinical practice was generated, and further well-designed and adequately powered RCTs are required to validate this conclusion.

The optimum timing to wean invasive ventilation for patients with AECOPD or COPD with pulmonary infection

COPD is characterized by a progressive decline in lung function and mental and physical comorbidities. It is a significant burden worldwide due to its growing prevalence, comorbidities, and mortality. Complication by bronchial-pulmonary infection causes 50%-90% of acute exacerbations of COPD (AECOPD), which may lead to the aggregation of COPD symptoms and the development of acute respiratory failure. Non-invasive or invasive ventilation (IV) is usually implemented to treat acute respiratory failure. However, ventilatory support (mainly IV) should be discarded as soon as possible to prevent the onset of time-dependent complications. To withdraw IV, an optimum timing has to be selected based on weaning assessment and spontaneous breathing trial or replacement of IV by non-IV at pulmonary infection control window. The former method is more suitable for patients with AECOPD without significant bronchial-pulmonary infection while the latter method is more suitable for patients with AECOPD with acute significant bronchial-pulmonary infection.

Noninvasive positive pressure ventilation for acute respiratory failure following upper abdominal surgery

BACKGROUND

Each year, more than four million abdominal surgeries are performed in the US and over 250,000 in England. Acute respiratory failure, a common complication that can affect 30% to 50% of people after upper abdominal surgery, can lead to significant morbidity and mortality. Noninvasive ventilation has been associated with lower rates of tracheal intubation in adults with acute respiratory failure, thus reducing the incidence of complications and mortality. This review compared the effectiveness and safety of noninvasive positive pressure ventilation (NPPV) versus standard oxygen therapy in the treatment of acute respiratory failure after upper abdominal surgery.

OBJECTIVES

To assess the effectiveness and safety of noninvasive positive pressure ventilation (NPPV), that is, continuous positive airway pressure (CPAP) or bilevel NPPV, in reducing mortality and the rate of tracheal intubation in adults with acute respiratory failure after upper abdominal surgery, compared to standard therapy (oxygen therapy), and to assess changes in arterial blood gas levels, hospital and intensive care unit (ICU) length of stay, gastric insufflation, and anastomotic leakage.

SEARCH METHODS

The date of the last search was 12 May 2015. We searched the following databases: the Cochrane Handbook for Systematic Reviews of Interventions (CENTRAL) (2015, Issue 5), MEDLINE (Ovid SP, 1966 to May 2015), EMBASE (Ovid SP, 1974 to May 2015); the physiotherapy evidence database (PEDro) (1999 to May 2015); the Cumulative Index to Nursing and Allied Health Literature (CINAHL, EBSCOhost, 1982 to May 2015), and LILACS (BIREME, 1986 to May 2015). We reviewed reference lists of included studies and contacted experts. We also searched grey literature sources. We checked databases of ongoing trials such as www.controlled-trials.com/ and www.trialscentral.org/. We did not apply language restrictions.

SELECTION CRITERIA

We selected randomized or quasi-randomized controlled trials involving adults with acute respiratory failure after upper abdominal surgery who were treated with CPAP or bilevel NPPV with, or without, drug therapy as standard medical care, compared to adults treated with oxygen therapy with, or without, standard medical care.

DATA COLLECTION AND ANALYSIS

Two authors independently selected and abstracted data from eligible studies using a standardized form. We evaluated study quality by assessing allocation concealment; random sequence generation; incomplete outcome data; blinding of participants, personnel, and outcome assessors; selective reporting; and adherence to the intention-to-treat (ITT) principle.

MAIN RESULTS

We included two trials involving 269 participants. The participants were mostly men (67%); the mean age was 65 years. The trials were conducted in China and Italy (one was a multicentre trial). Both trials included adults with acute respiratory failure after upper abdominal surgery. We judged both trials at high risk of bias. Compared to oxygen therapy, CPAP or bilevel NPPV may reduce the rate of tracheal intubation (risk ratio (RR) 0.25; 95% confidence interval (CI) 0.08 to 0.83; low quality evidence) with a number needed to treat for an additional beneficial outcome of 11. There was very low quality evidence that the intervention may also reduce ICU length of stay (mean difference (MD) -1.84 days; 95% CI -3.53 to -0.15). We found no differences for mortality (low quality evidence) and hospital length of stay. There was insufficient evidence to be certain that CPAP or NPPV had an effect on anastomotic leakage, pneumonia-related complications, and sepsis or infections. Findings from one trial of 60 participants suggested that bilevel NPPV, compared to oxygen therapy, may improve blood gas levels and blood pH one hour after the intervention (partial pressure of arterial oxygen (PaO2): MD 22.5 mm Hg; 95% CI 17.19 to 27.81; pH: MD 0.06; 95% CI 0.01 to 0.11; partial pressure of arterial carbon dioxide (PCO2) levels (MD -9.8 mm Hg; 95% CI -14.07 to -5.53). The trials included in this systematic review did not present data on the following outcomes that we intended to assess: gastric insufflation, fistulae, pneumothorax, bleeding, skin breakdown, eye irritation, sinus congestion, oronasal drying, and patient-ventilator asynchrony.

AUTHORS' CONCLUSIONS

The findings of this review indicate that CPAP or bilevel NPPV is an effective and safe intervention for the treatment of adults with acute respiratory failure after upper abdominal surgery. However, based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, the quality of the evidence was low or very low. More good quality studies are needed to confirm these findings.

Safety and efficacy of bronchoalveolar lavage using a laryngeal mask airway in cases of acute hypoxaemic respiratory failure with diffuse lung infiltrates

Objective Fibre-optic bronchoscopy with bronchoalveolar lavage (FOB-BAL) is an important tool for diagnosing and selecting treatment for acutely hypoxaemic patients with diffuse lung infiltrates. However, FOB-BAL carries a risk of significant hypoxaemia and subsequent tracheal intubation during and after the procedure. The application of FOB-BAL using a laryngeal mask airway (LMA) in combination with continuous positive airway pressure (CPAP) may minimize the incidence of hypoxaemia; however, the safety and efficacy of this procedure have not been investigated. Methods A retrospective chart review was performed from April to September 2013. Data regarding the recovered volume of BAL fluid, incidence of tracheal intubation within eight hours after the completion of FOB-BAL, respiratory and haemodynamic parameters and treatment modifications were collected for the evaluation. Results Ten trials of FOB-BAL using an LMA and CPAP were performed in nine patients with severe acute hypoxaemia associated with diffuse lung infiltrates. The BAL fluid recovery rate was 56%, and the procedure was completed without subsequent complications. In addition, the percutaneous arterial oxygen saturation decreased to 95.7%±3.8%, although it was never lower than 90.0% during the procedure, and no patients required intubation. Furthermore, the arterial blood pressure significantly but transiently decreased due to sedation, and the procedure yielded diagnostic information in all nine patients. Conclusion FOB-BAL using LMA and CPAP appears to be safe and effective in patients who develop severe acute hypoxaemia.

Automated weaning and SBT systems versus non-automated weaning strategies for weaning time in invasively ventilated critically ill adults

BACKGROUND

Automated systems use closed-loop control to enable ventilators to perform basic and advanced functions while supporting respiration. SmartCare™ is a unique automated weaning system that measures selected respiratory variables, adapts ventilator output to individual patient needs by operationalizing predetermined algorithms and automatically conducts spontaneous breathing trials (SBTs) when predetermined thresholds are met.

OBJECTIVES

The primary objective of this review was to compare weaning time (time from randomization to extubation as defined by study authors) between invasively ventilated critically ill adults weaned by automated weaning and SBT systems versus non-automated weaning strategies.As secondary objectives, we ascertained differences between effects of alternative weaning strategies on clinical outcomes (time to successful extubation, time to first SBT and first successful SBT, mortality, ventilator-associated pneumonia, total duration of ventilation, lengths of intensive care unit (ICU) and hospital stay, use of non-invasive ventilation (NIV), adverse events and clinician acceptance).The third objective of our review was to use subgroup analyses to explore variations in weaning time, length of ICU stay, mortality, ventilator-associated pneumonia, use of NIV and reintubation according to (1) the type of clinician primarily involved in implementing the automated weaning and SBT strategy, (2) the ICU (as a reflection of the population involved) and (3) the non-automated (control) weaning strategy utilized.We conducted a sensitivity analysis to evaluate variations in weaning time based on (4) the methodological quality (low or unclear versus high risk of bias) of the included studies.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 5; MEDLINE (1966 to 31 May 2013); EMBASE (1988 to 31 May 2013); the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 31 May 2013), Evidence-Based Medicine Reviews and Ovid HealthSTAR (1999 to 31 May 2013), as well as conference proceedings and trial registration websites; we also contacted study authors and content experts to identify potentially eligible trials.

SELECTION CRITERIA

Randomized and quasi-randomized trials comparing automated weaning and SBT systems versus non-automated weaning strategies in intubated adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and abstracted data according to prespecified criteria. Sensitivity and subgroup analyses were planned to assess the impact on selected outcomes of the following: (1) the type of clinician primarily involved in implementing automated weaning and SBT systems, (2) the ICU (as a reflection of the population involved) and (3) the non-automated (control) weaning strategy utilized.

MAIN RESULTS

We pooled summary estimates from 10 trials evaluating SmartCare™ involving 654 participants. Overall, eight trials were judged to be at low or unclear risk of bias, and two trials were judged to be at high risk of bias. Compared with non-automated strategies, SmartCare™ decreased weaning time (mean difference (MD) -2.68 days, 95% confidence interval (CI) -3.99 to -1.37; P value < 0.0001, seven trials, 495 participants, moderate-quality evidence), time to successful extubation (MD -0.99 days, 95% CI -1.89 to -0.09; P value 0.03, seven trials, 516 participants, low-quality evidence), length of ICU stay (MD -5.70 days, 95% CI -10.54 to -0.85; P value 0.02, six trials, 499 participants, moderate-quality evidence) and proportions of participants receiving ventilation for longer than seven and 21 days (risk ratio (RR) 0.44, 95% CI 0.23 to 0.85; P value 0.01 and RR 0.39, 95% CI 0.18 to 0.86; P value 0.02). SmartCare™ reduced the total duration of ventilation (MD -1.68 days, 95% CI -3.33 to -0.03; P value 0.05, seven trials, 521 participants, low-quality evidence) and the number of participants receiving ventilation for longer than 14 days (RR 0.61, 95% CI 0.37 to 1.00; P value 0.05); however the estimated effects were imprecise. SmartCare™ had no effect on time to first successful SBT, mortality or adverse events, specifically reintubation. Subgroup analysis suggested that trials with protocolized (versus non-protocolized) control weaning strategies reported significantly shorter ICU stays. Sensitivity analysis excluded two trials with high risk of bias and supported a trend toward significant reductions in weaning time favouring SmartCare™.

AUTHORS' CONCLUSIONS

Compared with non-automated weaning strategies, weaning with SmartCare™ significantly decreased weaning time, time to successful extubation, ICU stay and proportions of patients receiving ventilation for longer than seven days and 21 days. It also showed a favourable trend toward fewer patients receiving ventilation for longer than 14 days; however the estimated effect was imprecise. Summary estimates from our review suggest that these benefits may be achieved without increasing the risk of adverse events, especially reintubation; however, the quality of the evidence ranged from low to moderate, and evidence was derived from 10 small randomized controlled trials.

Pressure support versus T-tube for weaning from mechanical ventilation in adults

BACKGROUND

Mechanical ventilation is important in caring for patients with critical illness. Clinical complications, increased mortality, and high costs of health care are associated with prolonged ventilatory support or premature discontinuation of mechanical ventilation. Weaning refers to the process of gradually or abruptly withdrawing mechanical ventilation. The weaning process begins after partial or complete resolution of the underlying pathophysiology precipitating respiratory failure and ends with weaning success (successful extubation in intubated patients or permanent withdrawal of ventilatory support in tracheostomized patients).

OBJECTIVES

To evaluate the effectiveness and safety of two strategies, a T-tube and pressure support ventilation, for weaning adult patients with respiratory failure that required invasive mechanical ventilation for at least 24 hours, measuring weaning success and other clinically important outcomes.

SEARCH METHODS

We searched the following electronic databases: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 6); MEDLINE (via PubMed) (1966 to June 2012); EMBASE (January 1980 to June 2012); LILACS (1986 to June 2012); CINAHL (1982 to June 2012); SciELO (from 1997 to August 2012); thesis repository of CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) (http://capesdw.capes.gov.br/capesdw/) (August 2012); and Current Controlled Trials (August 2012).We reran the search in December 2013. We will deal with any studies of interest when we update the review.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared a T-tube with pressure support (PS) for the conduct of spontaneous breathing trials and as methods of gradual weaning of adult patients with respiratory failure of various aetiologies who received invasive mechanical ventilation for at least 24 hours.

DATA COLLECTION AND ANALYSIS

Two authors extracted data and assessed the methodological quality of the included studies. Meta-analyses using the random-effects model were conducted for nine outcomes. Relative risk (RR) and mean difference (MD) or standardized mean difference (SMD) were used to estimate the treatment effect, with 95% confidence intervals (CI).

MAIN RESULTS

We included nine RCTs with 1208 patients; 622 patients were randomized to a PS spontaneous breathing trial (SBT) and 586 to a T-tube SBT. The studies were classified into three categories of weaning: simple, difficult, and prolonged. Four studies placed patients in two categories of weaning. Pressure support ventilation (PSV) and a T-tube were used directly as SBTs in four studies (844 patients, 69.9% of the sample). In 186 patients (15.4%) both interventions were used along with gradual weaning from mechanical ventilation; the PS was gradually decreased, twice a day, until it was minimal and periods with a T-tube were gradually increased to two and eight hours for patients with difficult and prolonged weaning. In two studies (14.7% of patients) the PS was lowered to 2 to 4 cm H2O and 3 to 5 cm H2O based on ventilatory parameters until the minimal PS levels were reached. PS was then compared to the trial with the T-tube (TT).We identified 33 different reported outcomes in the included studies; we took 14 of them into consideration and performed meta-analyses on nine. With regard to the sequence of allocation generation, allocation concealment, selective reporting and attrition bias, no study presented a high risk of bias. We found no clear evidence of a difference between PS and TT for weaning success (RR 1.07, 95% CI 0.97 to 1.17, 9 studies, low quality of evidence), intensive care unit (ICU) mortality (RR 0.81, 95% CI 0.53 to 1.23, 5 studies, low quality of evidence), reintubation (RR 0.92, 95% CI 0.66 to 1.26, 7 studies, low quality evidence), ICU and long-term weaning unit (LWU) length of stay (MD -7.08 days, 95% CI -16.26 to 2.1, 2 studies, low quality of evidence) and pneumonia (RR 0.67, 95% CI 0.08 to 5.85, 2 studies, low quality of evidence). PS was significantly superior to the TT for successful SBTs (RR 1.09, 95% CI 1.02 to 1.17, 4 studies, moderate quality of evidence). Four studies reported on weaning duration, however we were unable to combined the study data because of differences in how the studies presented their data. One study was at high risk of other bias and four studies were at high risk for detection bias. Three studies reported that the weaning duration was shorter with PS, and in one study the duration was shorter in patients with a TT.

AUTHORS' CONCLUSIONS

To date, we have found evidence of generally low quality from studies comparing pressure support ventilation (PSV) and with a T-tube. The effects on weaning success, ICU mortality, reintubation, ICU and LWU length of stay, and pneumonia were imprecise. However, PSV was more effective than a T-tube for successful spontaneous breathing trials (SBTs) among patients with simple weaning. Based on the findings of single trials, three studies presented a shorter weaning duration in the group undergoing PS SBT, however a fourth study found a shorter weaning duration with a T-tube.

Non-invasive mechanical ventilation and mortality in elderly immunocompromised patients hospitalized with pneumonia: a retrospective cohort study

Background

Mortality after pneumonia in immunocompromised patients is higher than for immunocompetent patients. The use of non-invasive mechanical ventilation for patients with severe pneumonia may provide beneficial outcomes while circumventing potential complications associated with invasive mechanical ventilation. The aim of our study was to determine if the use of non-invasive mechanical ventilation in elderly immunocompromised patients with pneumonia is associated with higher all-cause mortality.

Methods

In this retrospective cohort study, data were obtained from the Department of Veterans Affairs administrative databases. We included veterans age ≥65 years who were immunocompromised and hospitalized due to pneumonia. Multilevel logistic regression analysis was used to determine the relationship between the use of invasive versus non-invasive mechanical ventilation and 30-day and 90-day mortality.

Results

Of 1,946 patients in our cohort, 717 received non-invasive mechanical ventilation and 1,229 received invasive mechanical ventilation. There was no significant association between all-cause 30-day mortality and non-invasive versus invasive mechanical ventilation in our adjusted model (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.66-1.10). However, those patients who received non-invasive mechanical ventilation had decreased 90-day mortality (OR 0.66, 95% CI 0.52-0.84). Additionally, receipt of guideline-concordant antibiotics in our immunocompromised cohort was significantly associated with decreased odds of 30-day mortality (OR 0.31, 95% CI 0.24-0.39) and 90-day mortality (OR 0.41, 95% CI 0.31-0.53).

Conclusions

Our findings suggest that physicians should consider the use of non-invasive mechanical ventilation, when appropriate, for elderly immunocompromised patients hospitalized with pneumonia.

Noninvasive ventilation as a weaning strategy for mechanical ventilation in adults with respiratory failure: a Cochrane systematic review

BACKGROUND

Noninvasive ventilation has been studied as a means of reducing complications among patients being weaned from invasive mechanical ventilation. We sought to summarize evidence comparing noninvasive and invasive weaning and their effects on mortality.

METHODS

We identified relevant randomized and quasirandomized trials through searches of databases, conference proceedings and grey literature. We included trials comparing extubation and immediate application of noninvasive ventilation with continued invasive weaning in adults on mechanical ventilation. Two reviewers each independently screened citations, assessed trial quality and abstracted data. Our primary outcome was mortality.

RESULTS

We identified 16 trials involving 994 participants, most of whom had chronic obstructive pulmonary disease (COPD). Compared with invasive weaning, noninvasive weaning significantly reduced mortality (risk ratio [RR] 0.53, 95% confidence interval [CI] 0.36 to 0.80), weaning failures (RR 0.63, 95% CI 0.42 to 0.96), ventilator-associated pneumonia (RR 0.25, 95% CI 0.15 to 0.43), length of stay in the intensive care unit (mean difference [MD] -5.59 d, 95% CI -7.90 to -3.28) and in hospital (MD -6.04 d, 95% CI -9.22 to -2.87), and total duration of mechanical ventilation (MD -5.64 d, 95% CI -9.50 to -1.77). Noninvasive weaning had no significant effect on the duration of ventilation related to weaning, but significantly reduced rates of tracheostomy (RR 0.19, 95% CI 0.08 to 0.47) and reintubation (RR 0.65, 95% CI 0.44 to 0.97). Mortality benefits were significantly greater in trials enrolling patients with COPD than in trials enrolling mixed patient populations (RR 0.36 [95% CI 0.24 to 0.56] v. RR 0.81 [95% CI 0.47 to 1.40]).

INTERPRETATION

Noninvasive weaning reduces rates of death and pneumonia without increasing the risk of weaning failure or reintubation. In subgroup analyses, mortality benefits were significantly greater in patients with COPD.

Noninvasive positive-pressure ventilation as a weaning strategy for intubated adults with respiratory failure

BACKGROUND

Noninvasive positive-pressure ventilation (NPPV) provides ventilatory support without the need for an invasive airway. Interest has emerged in using NPPV to facilitate earlier removal of an endotracheal tube and to decrease complications associated with prolonged intubation.

OBJECTIVES

We evaluated studies in which invasively ventilated adults with respiratory failure of any cause (chronic obstructive pulmonary disease (COPD), non-COPD, postoperative, nonoperative) were weaned by means of early extubation followed by immediate application of NPPV or continued IPPV weaning. The primary objective was to determine whether the noninvasive positive-pressure ventilation (NPPV) strategy reduced all-cause mortality compared with invasive positive-pressure ventilation (IPPV) weaning. Secondary objectives were to ascertain differences between strategies in proportions of weaning failure and ventilator-associated pneumonia (VAP), intensive care unit (ICU) and hospital length of stay (LOS), total duration of mechanical ventilation, duration of mechanical support related to weaning, duration of endotracheal mechanical ventilation (ETMV), frequency of adverse events (related to weaning) and overall quality of life. We planned sensitivity and subgroup analyses to assess (1) the influence on mortality and VAP of excluding quasi-randomized trials, and (2) effects on mortality and weaning failure associated with different causes of respiratory failure (COPD vs. mixed populations).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 5, 2013), MEDLINE (January 1966 to May 2013), EMBASE (January 1980 to May 2013), proceedings from four conferences, trial registration websites and personal files; we contacted authors to identify trials comparing NPPV versus conventional IPPV weaning.

SELECTION CRITERIA

Randomized and quasi-randomized trials comparing early extubation with immediate application of NPPV versus IPPV weaning in intubated adults with respiratory failure.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and abstracted data according to prespecified criteria. Sensitivity and subgroup analyses assessed (1) the impact of excluding quasi-randomized trials, and (2) the effects on selected outcomes noted with different causes of respiratory failure.

MAIN RESULTS

We identified 16 trials, predominantly of moderate to good quality, involving 994 participants, most with chronic obstructive pulmonary disease (COPD). Compared with IPPV weaning, NPPV weaning significantly decreased mortality. The benefits for mortality were significantly greater in trials enrolling exclusively participants with COPD (risk ratio (RR) 0.36, 95% confidence interval (CI) 0.24 to 0.56) versus mixed populations (RR 0.81, 95% CI 0.47 to 1.40). NPPV significantly reduced weaning failure (RR 0.63, 95% CI 0.42 to 0.96) and ventilator-associated pneumonia (RR 0.25, 95% CI 0.15 to 0.43); shortened length of stay in an intensive care unit (mean difference (MD) -5.59 days, 95% CI -7.90 to -3.28) and in hospital (MD -6.04 days, 95% CI -9.22 to -2.87); and decreased the total duration of ventilation (MD -5.64 days, 95% CI -9.50 to -1.77) and the duration of endotracheal mechanical ventilation (MD - 7.44 days, 95% CI -10.34 to -4.55) amidst significant heterogeneity. Noninvasive weaning also significantly reduced tracheostomy (RR 0.19, 95% CI 0.08 to 0.47) and reintubation (RR 0.65, 95% CI 0.44 to 0.97) rates. Noninvasive weaning had no effect on the duration of ventilation related to weaning. Exclusion of a single quasi-randomized trial did not alter these results. Subgroup analyses suggest that the benefits for mortality were significantly greater in trials enrolling exclusively participants with COPD versus mixed populations.

AUTHORS' CONCLUSIONS

Summary estimates from 16 trials of moderate to good quality that included predominantly participants with COPD suggest that a weaning strategy that includes NPPV may reduce rates of mortality and ventilator-associated pneumonia without increasing the risk of weaning failure or reintubation.

Neuroanesthesia and Intensive Care A meta-analysis of noninvasive weaning to facilitate liberation from mechanical ventilation

PURPOSE

To summarize the evidence comparing noninvasive positive pressure ventilation (NPPV) and invasive positive pressure ventilation (IPPV) weaning on mortality, ventilator associated pneumonia and the total duration of mechanical ventilation among invasively ventilated adults with respiratory failure.

SOURCE

Meta-analysis of randomized and quasi-randomized studies comparing early extubation with immediate application of NPPV to IPPV weaning. We selected randomized studies that 1) included adults, with respiratory failure, invasively ventilated for at least 24 hr; 2) compared extubation with immediate application of NPPV to weaning using IPPV; and 3) reported at least one clinically important outcome.

PRINCIPAL FINDINGS

We searched MEDLINE (1966 to 2003), EMBASE (1980 to 2003) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2003) for randomized controlled trials comparing NPPV and IPPV weaning. Additional data sources included personal files, conference proceedings and author contact. Two reviewers independently assessed trial quality and abstracted data. Five studies enrolling 171 patients demonstrated that compared to IPPV, noninvasive weaning decreased mortality (relative risk, 0.41 [95% confidence interval [CI] 0.22-0.76]), ventilator associated pneumonia (relative risk, 0.28 [95% CI 0.09-0.85]) and the total duration of mechanical ventilation (weighted mean difference, -7.33 days [95% CI -11.45 to -3.22 days]).

CONCLUSIONS

In the absence of a large randomized controlled trial, this meta-analysis demonstrated a consistent positive effect of noninvasive weaning on mortality. Notwithstanding, the use of NPPV to facilitate weaning, in mechanically ventilated patients, with predominantly chronic obstructive pulmonary disease, is associated with promising, but insufficient, evidence of net clinical benefit at present.

Wean earlier and automatically with new technology (the WEAN study). A multicenter, pilot randomized controlled trial

RATIONALE

Automated weaning has not been compared with a paper-based weaning protocol in North America.

OBJECTIVES

We conducted a pilot randomized trial comparing automated weaning with protocolized weaning in critically ill adults to evaluate clinician compliance and acceptance of the weaning and sedation protocols, recruitment, and impact on outcomes.

METHODS

From August 2007 to October 2009, we enrolled critically ill adults requiring more than 24 hours of mechanical ventilation and at least partial reversal of the condition precipitating respiratory failure at nine Canadian intensive care units. We randomized patients who tolerated at least 30 minutes of pressure support and either failed or were not yet ready to undergo a spontaneous breathing trial to automated or protocolized weaning. Both groups used pressure support, included spontaneous breathing trials, used a common positive end-expiratory pressure-FI(O(2)) chart, sedation protocol, and criteria for extubation, reintubation, and noninvasive ventilation.

MEASUREMENTS AND MAIN RESULTS

We recruited 92 patients (49 automated, 43 protocolized) over 26 months. Adherence to assigned weaning protocols and extreme sedation scale scores fell within prespecified thresholds. Combined physician-respiratory therapist and nurse acceptance scores of the study weaning and sedation protocols, respectively, were not significantly different. Automated weaning patients had significantly shorter median times to first successful spontaneous breathing trial (1.0 vs. 4.0 d; P < 0.0001), extubation (3.0 vs. 4.0 d; P = 0.02), and successful extubation (4.0 vs. 5.0 d; P = 0.01), and underwent fewer tracheostomies and episodes of protracted ventilation.

CONCLUSIONS

Compared with a standardized protocol, automated weaning was associated with promising outcomes that warrant further investigation. Minor protocol modifications may increase compliance, facilitate recruitment, and enhance feasibility. Clinical trial registered with www.controlled-trials.com (ISRCTN43760151).

Noninvasive ventilation: practical advice

PURPOSE OF REVIEW

This critical review discusses the key points that would be of practical help for the clinician who applies noninvasive ventilation (NIV) for treatment of patients with acute respiratory failure (ARF).

RECENT FINDINGS

In recent years, the growing role of NIV in the acute care setting has led to the development of technical innovations to overcome the problems related to gas leakage and dead space. A considerable amount of research has been conducted to improve the quality of the devices as well as optimize ventilation modes used to administer NIV. As a result, also mechanical ventilators have been implemented with modalities aimed at delivering NIV.

SUMMARY

The success of NIV in patients with ARF depends on several factors, including the skills of the clinician, selection of patient, choice of interface, selection of ventilation mode and ventilator setting, monitoring, and the motivation of the patient. Recent advances in the understanding of the physiological aspects of using NIV through different interfaces and ventilator settings have led to improve patient-machine interaction, enhancing favorable NIV outcome.

Interobserver agreement rate of the spontaneous breathing trial

PURPOSE

During the mechanical ventilation weaning process, the spontaneous breathing trial (SBT) is the confirmatory test of patients' capability to breathe unassisted. However, the SBT interobserver agreement rate (its reliability) is unknown, and our objective was to evaluate it.

MATERIALS AND METHODS

This is a prospective, multicentric and observational study. Patients were included when the SBT criteria were fulfilled. Two physicians and 2 respiratory therapists (RTs) rated each SBT. The SBT interobserver agreement was measured using κ statistic and also the percentage of agreement with its 95% credible interval (CrI) calculated by a Bayesian inference.

RESULTS

Ninety-three distinct physicians and 91 distinct RTs rated 130 SBTs. The κ coefficient was 0.46 for physicians and 0.57 for RT, indicating a moderate interobserver agreement rate. The percentage of agreement was 87.7% between physicians (95% CrI, 81.0%-92.3%) and 86.2% between RT (95% CrI, 79.2%-91.1%). The physicians' and RT' percentage of agreement were not statistically different (P = .71).

CONCLUSIONS

The SBT interobserver agreement rate is only moderate for physicians and RT. The percentage of agreement between 2 different SBT observers is 79.2% to 92.3%. Therefore, a relevant percentage of patients will have different extubation decisions depending on the SBT observer.

Non-invasive ventilation in immunosuppressed patients with pneumonia and extrapulmonary sepsis

PURPOSE

International guidelines recommend the use of noninvasive ventilation in immunocompromised patients with acute respiratory failure (ARF). We analyzed failure rates and risk factors for NIV failure in immunocompromised patients.

METHODS

We retrospectively analyzed 120 immunodeficient patients treated with NIV in our medical ICU from 2005 to 2011. We compared the clinical course and NIV failure rates. Furthermore, we compared patients with secondary respiratory failure due to those with Systemic Inflammatory Response Syndrome (SIRS) of other than pulmonary origin to those with primary pulmonary infiltrations.

RESULTS

Regression analyses revealed high APACHE II score (p < 0.01), need for catecholamines (p < 0.05) and low paO(2)/FIO(2) ratio (p < 0.05) as risk factors for NIV failure. Regarding the underlying diseases, we could not find differences in NIV duration (p = 0.07) and outcome (p = 0.44). 59.2% suffered from ARF due to lung infiltrations whereas 40.8% had secondary ARF caused by sepsis of extrapulmonary origin. Patients with lung infiltrations had a longer stay on ICU (16.3 vs 13.2 days; p = 0.047) and showed a trend toward longer NIV duration (87 ± 102 h vs 65.6 ± 97.8 h; p = 0.056). The SIRS patients compared to pneumonia patients showed a trend toward higher serum creatinine (1.63 mg/dL to 1.51 mg/dL; p = 0.059), a higher rate of renal failure (p < 0.01), higher APACHE II score (30.6-25.7, p < 0.01) and more frequently needed catecholamines (p < 0.01). NIV failure rate (overall 55%) was not different.

CONCLUSIONS

Almost 50% of the immunocompromised patients treated with NIV did not require intubation independent of the etiology of ARF. High APACHE II scores and severity of oxygenation failure were associated with NIV failure.

Mechanobiology in lung epithelial cells: measurements, perturbations, and responses

Epithelial cells of the lung are located at the interface between the environment and the organism and serve many important functions including barrier protection, fluid balance, clearance of particulate, initiation of immune responses, mucus and surfactant production, and repair following injury. Because of the complex structure of the lung and its cyclic deformation during the respiratory cycle, epithelial cells are exposed to continuously varying levels of mechanical stresses. While normal lung function is maintained under these conditions, changes in mechanical stresses can have profound effects on the function of epithelial cells and therefore the function of the organ. In this review, we will describe the types of stresses and strains in the lungs, how these are transmitted, and how these may vary in human disease or animal models. Many approaches have been developed to better understand how cells sense and respond to mechanical stresses, and we will discuss these approaches and how they have been used to study lung epithelial cells in culture. Understanding how cells sense and respond to changes in mechanical stresses will contribute to our understanding of the role of lung epithelial cells during normal function and development and how their function may change in diseases such as acute lung injury, asthma, emphysema, and fibrosis.

A clinical assessment of the Mucus Shaver: a device to keep the endotracheal tube free from secretions

OBJECTIVE

: We evaluated a new device designed to clean the endotracheal tube in mechanically ventilated patients, the Mucus Shaver.

DESIGN

: Prospective, randomized trial.

SETTING

: University hospital intensive care unit.

PATIENTS

: We enrolled 24 patients expected to remain ventilated for >72 hrs.

INTERVENTIONS

: The Mucus Shaver is a concentric inflatable catheter for the removal of mucus and secretions from the interior surface of the endotracheal tube. The Mucus Shaver is advanced to the distal endotracheal tube tip, inflated, and subsequently withdrawn over a period of 3-5 secs. Patients were prospectively randomized within 2 hrs of intubation to receive standard endotracheal tube suctioning treatment or standard suctioning plus Mucus Shaver use until extubation.

MEASUREMENTS AND MAIN RESULTS

: During the study period, demographic data, recent medical history, adverse events, and staff evaluation of the Mucus Shaver were recorded. At extubation, each endotracheal tube was removed, cultured, and analyzed by scanning electron microscopy. Twelve patients were assigned to the study group and 12 were assigned to the control group. No adverse events related to the use of the Mucus Shaver were observed. At extubation, only one endotracheal tube from the Mucus Shaver group was colonized, whereas in the control group ten endotracheal tubes were colonized (8% vs. 83%; p < .001). Scanning electron microscopy showed little secretions on the endotracheal tubes from the study group, whereas thick bacterial deposits were present on all the endotracheal tubes from the control group (p < .001 by Fisher exact test, using a maximum biofilm thickness of 30 μm as cut-off). The nursing staff was satisfied by the overall safety, feasibility, and efficacy of the Mucus Shaver.

CONCLUSIONS

: The Mucus Shaver is a safe, feasible, and efficient device for endotracheal tube cleaning in the clinical setting. The Mucus Shaver is helpful in preventing endotracheal tube colonization by potentially harmful microorganisms.

Immune Enteral Nutrition Can Improve Outcomes in Medical-Surgical Patients with ARDS: A Prospective Randomized Controlled Trial

Objective

To determine if early continuous enteral feeding of a diet containing eicosapentaenoic acid (EPA), gamma-linolenic acid (GLA), docosahexaenoic acid, and antioxidants in surgical-medical patients with ARDS improves Lung Injury Score (LIS), gas exchange, Multiple Organ Dysfunction (MOD) Score, ICU length of stay, and days on mechanical ventilation.

Methods

Prospective randomized 2-center double-blind controlled trial of 17 ARDS patients whom continuously tube-fed the experimental diet (n=9) or an isonitrogenous, isocaloric standard diet (n=8) at a minimum caloric delivery of 90% of basal energy expenditure.

Results

In the experimental group, there was a decrease in lung injury score (p < 0.003) and lower ventilation variables (p < 0.001). Patients in the experimental group had a statistically significant decrease in 28-day MOD score (p < 0.05). The length of ICU stay was significantly decreased in the experimental group (12.8 vs. 17.5 days; p = 0.01). The study was underpowered to detect any survival benefits between the two groups.

Conclusion

An EPA and GLA supplemented diet contributes to improved gas exchange in addition to decrease LIS, MOD scores and length of ICU stay in patients with ARDS. An EPA+GLA-enriched enteral diet may be an effective tool in the medical management of ARDS.

Evaluation of consulting and critiquing decision support systems: effect on adherence to a lower tidal volume mechanical ventilation strategy

PURPOSE

Our hypothesis was that both styles are effective to decrease tidal volume (V(T)) but that critiquing comprises the most effective strategy. The purpose of this study is to test this hypothesis by measuring the effect of an active computerized decision support system, in 2 communication styles, consulting and critiquing, on adherence to V(T) recommendations.

MATERIALS AND METHODS

We developed and implemented an active computerized decision support system (CDSS) working in a consulting style that always shows the preferred V(T) and in a critiquing style that shows the preferred V(T) only if V(T) is above the desired threshold. A prospective, off-on-off-on study evaluated the system's performance in a mixed medical-surgical intensive care unit of a university hospital.

RESULTS

Four thousand seven hundred sixty-four patient-day mechanical ventilation from 757 patients were analyzed. The percentage of ventilation time in excess of 6 and 8 mL/kg predicted body weight decreased significantly after intervening with the consulting style (12% reduction and P < .001; 22% reduction and P < .001) and again increased after stopping the CDSS (11% increase and P < .001; 29% increase and P < .001). With the critiquing CDSS, the percentage of ventilation time in excess of 6 and 8 mL/kg predicted body weight again decreased significantly (6% reduction and P < .001; 15% reduction and P < .001).

CONCLUSIONS

The use of a CDSS in both communication styles improved the use of lower V(T)s for ventilated patients. When decision support was not sustained, adherence to low V(T) fell back to its original value. Interestingly, the consulting style had a slightly larger effect. This may stem from the high frequency of showing reminders in this style and the relatively simple underlying guideline where its display implies the associated action of lowering V(T). The consulting style, however, was more interruptive for clinicians, calling upon the need to strike a balance between effect and intrusiveness.

Predicting the success of non-invasive ventilation in preventing intubation and re-intubation in the paediatric intensive care unit

PURPOSE

To determine whether physiological parameters and underlying condition can be used to predict which patients can be managed successfully on non-invasive ventilation (NIV).

METHODS

Review of case notes and computerised data of every paediatric intensive care unit (PICU) admission over 7 years where NIV was commenced. Data immediately prior to commencing NIV and 2 h after its establishment was collected. Univariable and multivariable statistical analysis was performed to compare variables.

RESULTS

Eighty-three patients commenced NIV attempting to avoid intubation and 64% succeeded. Those who failed required a higher FiO2 (0.56 vs. 0.47, p = 0.038), had higher respiratory rates (53.3 vs. 40.3 breaths/min, p = 0.012) and lower pH (7.26 vs. 7.34, p = 0.032) before NIV and higher FiO2 after NIV commenced (0.54 vs. 0.43, p = 0.009). Those with a respiratory diagnosis were more likely to be successful. Patients with oncologic disease, particularly if septic, were less likely to avoid intubation using NIV. Multivariable models showed that after adjustment for mode of NIV and underlying diagnosis, respiratory rate before NIV was an independent predictor of success [adjusted odds ratio (OR) 0.95 (0.91, 0.99), p = 0.01]. Eighty patients were extubated to NIV but 15 required re-intubation. Those re-intubated had a higher systolic blood pressure (104 vs. 77.9 mmHg, p = 0.001) and diastolic blood pressure (64.5 vs. 54.1 mmHg, p = 0.0037) after extubation. Multivariable models showed that systolic blood pressure 2 h after extubation was independently associated with outcome [adjusted OR 0.96 (0.93, 0.99), p = 0.007].

CONCLUSIONS

Parameters relating to respiratory and cardiovascular status can determine which patients will successfully avoid intubation or re-intubation when placed on NIV. Underlying disease and reason for admission should be considered when predicting the outcome of NIV.

Ventilator-induced lung injury: historical perspectives and clinical implications

Mechanical ventilation can produce lung physiological and morphological alterations termed ventilator-induced lung injury (VILI). Early experimental studies demonstrated that the main determinant of VILI is lung end-inspiratory volume. The clinical relevance of these experimental findings received resounding confirmation with the results of the acute respiratory distress syndrome (ARDS) Network study, which showed a 22% reduction in mortality in patients with the acute respiratory distress syndrome through a simple reduction in tidal volume. In contrast, the clinical relevance of low lung volume injury remains debated and the application of high positive end-expiratory pressure levels can contribute to lung overdistension and thus be deleterious. The significance of inflammatory alterations observed during VILI is debated and has not translated into clinical application. This review examines seminal experimental studies that led to our current understanding of VILI and contributed to the current recommendations in the respiratory support of ARDS patients.

[Does noninvasive ventilation avoid intubation of the critical patient?]

In recent years we have witnessed an increased use of noninvasive ventilation (NIV) in our intensive care units (ICUs). Its use is intended mainly in cases of acute respiratory failure (ARF), in order to improve arterial oxygenation, increase alveolar ventilation, decrease work of breathing and avoid intubation. For this reason, we designed a study that has aimed to quantify the number of patients who have benefited from NIV during their admission, to know the type of NIV used in these patients and to determine whether the use of NIV has avoided tracheal intubation. We performed a retrospective, observational and descriptive study in two polyvalent ICUs of a tertiary hospital, with 80 patients with NIV during admission. 65% men and 35% women. Mean age: ±61 years (47-75). Average stay: ±10 days (2-18). NIV mode used was double positive pressure with Nellcor Puritan Bennett® 840. A total of 46% of patients treated with NIV required intubation, thus extending their stay in the ICU by ±6 days. Most patients treated with NIV had a history of chronic obstructive pulmonary disease (COPD) and / or were carriers of VNI with continuous positive pressure (CPAP) at home. Following this analysis, we concluded that treatment with NIV did not prevent tracheal intubation in a considerable number of patients (37) diagnosed with ARF and the NIV was effective in patients with a history of COPD and / or CPAP at home.

Noninvasive positive pressure ventilation as a weaning strategy for intubated adults with respiratory failure

BACKGROUND

Noninvasive positive pressure ventilation (NPPV) provides ventilatory support without the need for an invasive airway approach. Interest has emerged in using NPPV to facilitate earlier removal of an endotracheal tube and decrease complications associated with prolonged intubation.

OBJECTIVES

To summarize the evidence comparing NPPV and invasive positive pressure ventilation (IPPV) weaning on clinical outcomes in intubated adults with respiratory failure.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2008), MEDLINE (January 1966 to April 2008), EMBASE (January 1980 to April 2008), proceedings from four conferences, and personal files; and contacted authors to identify randomized controlled trials comparing NPPV and IPPV weaning.

SELECTION CRITERIA

Randomized and quasi-randomized studies comparing early extubation with immediate application of NPPV to IPPV weaning in intubated adults with respiratory failure.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and abstracted data according to prespecified criteria. Sensitivity and subgroup analyses were planned to assess the impact of (i) excluding quasi-randomized trials, and (ii) the etiology of respiratory failure on selected outcomes.

MAIN RESULTS

We identified 12 trials of moderate to good quality that involved 530 participants with predominantly chronic obstructive pulmonary disease (COPD). Compared to the IPPV strategy, NPPV significantly decreased mortality (relative risk (RR) 0.55, 95% confidence Interval (CI) 0.38 to 0.79), ventilator associated pneumonia (RR 0.29, 95% CI 0.19 to 0.45), length of stay in an intensive care unit (weighted mean difference (WMD) -6.27 days, 95% CI -8.77 to -3.78) and hospital (WMD -7.19 days, 95% CI -10.80 to -3.58), total duration of ventilation (WVD) -5.64 days (95% CI -9.50 to -1.77) and duration of endotracheal mechanical ventilation (WMD - 7.81 days, 95% CI -11.31 to -4.31). Noninvasive weaning had no effect on weaning failures or the duration of ventilation related to weaning. Excluding a single quasi-randomized trial maintained the significant reduction in mortality and ventilator associated pneumonia. Subgroup analyses suggested that the benefits on mortality and weaning failures were nonsignificantly greater in trials enrolling exclusively COPD patients versus mixed populations.

AUTHORS' CONCLUSIONS

Summary estimates from 12 small studies of moderate to good quality that included predominantly COPD patients demonstrated a consistent, positive effect on mortality and ventilator associated pneumonia. The net clinical benefits associated with noninvasive weaning remain to be fully elucidated.

Diagnostic accuracy of the rapid shallow breathing index to predict a successful spontaneous breathing trial outcome in mechanically ventilated patients with chronic obstructive pulmonary disease

OBJECTIVE

To evaluate the diagnostic accuracy of 2 threshold values (105 breaths per minute [bpm]/L and 130 bpm/L) of the rapid shallow breathing index (RSBI) to predict a successful weaning trial outcome in a homogenous group of patients with chronic obstructive pulmonary disease (COPD).

METHODS

A consecutive population of patients with COPD who were intubated for hypercapnic respiratory failure during a 2-year period were studied prospectively. RSBI was measured by 2 investigators at minute 5 of the T-piece trial, whereas 2 other physicians evaluated the 30 minute T-piece trial as successful or unsuccessful, according to clinical criteria.

RESULTS

Of 64 patients with COPD (53 male, 11 female) who constituted the study population, 42 patients (35 male, 7 female; aged 70 ± 9.2 years) completed the spontaneous breathing trial (SBT) and remained clinically stable (group 1). The remaining 22 patients (18 male, 4 female; aged 71.9 ± 4.7 years) had to return to ventilatory support by the end of the SBT because of clinical deterioration (group 2). The 2 threshold values that were evaluated had low specificity (38.1% for < 105 bpm/L and 66.7% for < 130 bpm/L), low sensitivity (63.6% for < 105 bpm/L and 54.5% for < 130 bpm/L), and low diagnostic accuracy (46.8% for < 105 bpm/L and 65.6% for < 130 bpm/L) in predicting a successful T-piece trial outcome.

CONCLUSION

RSBI measured early during an SBT cannot accurately predict the successful outcome of a T-piece trial in a homogenous population of patients with COPD.