Comparative Effectiveness of Noninvasive and Invasive Ventilation in Critically Ill Patients With Acute Exacerbation of Chronic Obstructive Pulmonary Disease

[Non-invasive Mechanical Ventilation in Acute Respiratory Failure. Clinical Practice Guidelines - on behalf of the German Society of Pneumology and Ventilatory Medicine]

The guideline update outlines the advantages as well as the limitations of NIV in the treatment of acute respiratory failure in daily clinical practice and in different indications.Non-invasive ventilation (NIV) has a high value in therapy of hypercapnic acute respiratory failure, as it significantly reduces the length of ICU stay and hospitalization as well as mortality.Patients with cardiopulmonary edema and acute respiratory failure should be treated with continuous positive airway pressure (CPAP) and oxygen in addition to necessary cardiological interventions. This should be done already prehospital and in the emergency department.In case of other forms of acute hypoxaemic respiratory failure with only mild or moderately disturbed gas exchange (PaO2/FiO2 > 150 mmHg) there is no significant advantage or disadvantage compared to high flow nasal oxygen (HFNO). In severe forms of ARDS NIV is associated with high rates of treatment failure and mortality, especially in cases with NIV-failure and delayed intubation.NIV should be used for preoxygenation before intubation. In patients at risk, NIV is recommended to reduce extubation failure. In the weaning process from invasive ventilation NIV essentially reduces the risk of reintubation in hypercapnic patients. NIV is regarded useful within palliative care for reduction of dyspnea and improving quality of life, but here in concurrence to HFNO, which is regarded as more comfortable. Meanwhile NIV is also recommended in prehospital setting, especially in hypercapnic respiratory failure and pulmonary edema.With appropriate monitoring in an intensive care unit NIV can also be successfully applied in pediatric patients with acute respiratory insufficiency.

Impact of AKI on metabolic compensation for respiratory acidosis in ICU patients with AECOPD

PURPOSE

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) can result in severe respiratory acidosis. Metabolic compensation is primarily achieved by renal retention of bicarbonate. The extent to which acute kidney injury (AKI) impairs the kidney's capacity to compensate for respiratory acidosis remains unclear.

MATERIALS AND METHODS

This retrospective analysis covers clinical data between January 2009 and December 2021 for 498 ICU patients with AECOPD and need for respiratory support.

RESULTS

278 patients (55.8%) presented with or developed AKI. Patients with AKI exhibited higher 30-day-mortality rates (14.5% vs. 4.5% p = 0.001), longer duration of mechanical ventilation (median 90 h vs. 14 h; p = 0.001) and more severe hypercapnic acidosis (pH 7.23 vs. 7.28; pCO2 68.5 mmHg vs. 61.8 mmHg). Patients with higher AKI stages exhibited lower HCO3-/pCO2 ratios and did not reach expected HCO3- levels. In a mixed model analysis with random intercept per patient we analyzed the association of pCO2 (independent) and HCO3- (dependent variable). Lower estimates for averaged change in HCO3- were observed in patients with more severe AKI.

CONCLUSION

AKI leads to poor outcomes and compromises metabolic compensation of respiratory acidosis in ICU patients with AECOPD. While buffering agents may aid compensation for severe AKI, their use should be approached with caution.

A risk prediction model for efficient intubation in the emergency department: A 4-year single-center retrospective analysis

Objective

To analyze the risk factors associated with intubated critically ill patients in the emergency department (ED) and develop a prediction model by machine learning algorithms.

Methods

This study was conducted in an academic tertiary hospital in Hangzhou, China. Critically ill patients admitted to the ED were retrospectively analyzed from May 2018 to July 2022. The demographic characteristics, distribution of organ dysfunction, parameters for different organs' examination, and status of mechanical ventilation were recorded. These patients were assigned to the intubation and non-intubation groups according to ventilation support. We used the eXtreme Gradient Boosting (XGBoost) algorithm to develop the prediction model and compared it with other algorithms, such as logistic regression, artificial neural network, and random forest. SHapley Additive exPlanations was used to analyze the risk factors of intubated critically ill patients in the ED.

Results

Of 14,589 critically ill patients, 10,212 comprised the training group and 4377 comprised the test group; 2289 intubated patients were obtained from the electronic medical records. The mean age, mean scores of vital signs, parameters of different organs, and blood oxygen examination results differed significantly between the two groups (p < 0.05). The white blood cell count, international normalized ratio, respiratory rate, and pH are the top four risk factors for intubation in critically ill patients. Based on the risk factors in different predictive models, the XGBoost model showed the highest area under the receiver operating characteristic curve (0.84) for predicting ED intubation.

Conclusions

For critically ill patients in the ED, the proposed model can predict potential intubation based on the risk factors in the clinically predictive model.

Reinforcement Learning Model for Managing Noninvasive Ventilation Switching Policy

Noninvasive ventilation (NIV) has been recognized as a first-line treatment for respiratory failure in patients with chronic obstructive pulmonary disease (COPD) and hypercapnia respiratory failure, which can reduce mortality and burden of intubation. However, during the long-term NIV process, failure to respond to NIV may cause overtreatment or delayed intubation, which is associated with increased mortality or costs. Optimal strategies for switching regime in the course of NIV treatment remain to be explored.For the goal of reducing 28-day mortality of the patients undergoing NIV, Double Dueling Deep Q Network (D3QN) of offline-reinforcement learning algorithm was adopted to develop an optimal regime model for making treatment decisions of discontinuing ventilation, continuing NIV, or intubation. The model was trained and tested using the data from Multi-Parameter Intelligent Monitoring in Intensive Care III (MIMIC-III) and evaluated by the practical strategies. Furthermore, the applicability of the model in majority disease subgroups (Catalogued by International Classification of Diseases, ICD) was investigated. Compared with physician's strategies, the proposed model achieved a higher expected return score (4.25 vs. 2.68) and its recommended treatments reduced the expected mortality from 27.82% to 25.44% in all NIV cases. In particular, for these patients finally received intubation in practice, if the model also supported the regime, it would warn of switching to intubation 13.36 hours earlier than clinicians (8.64 vs. 22 hours after the NIV treatment), granting a 21.7% reduction in estimated mortality. In addition, the model was applicable across various disease groups with distinguished achievement in dealing with respiratory disorders. The proposed model is promising to dynamically provide personalized optimal NIV switching regime for patients undergoing NIV with the potential of improving treatment outcomes.

Acute Hypercapnic Respiratory Failure in COPD

COPD is a progressive inflammatory process affecting both the airways and alveolar structures of the lungs. Exacerbations of COPD are episodes of acute worsening of this inflammatory process, often triggered by infections. The most severe exacerbations are characterized by substantial air trapping and inspiratory muscle overload, which leads to hypercapnic respiratory failure. Pharmacologic therapies focus on intense bronchodilator administration (usually by aerosol), corticosteroids, and antibiotics. Respiratory life support technologies are often needed for severe exacerbations and range from carefully titrated supplemental O2 administration to positive-pressure ventilation (both invasive and noninvasive). Future life support strategies will likely involve extracorporeal life support technologies.

Pilot testing the impact of an aerobic exercise plus rehabilitation training on respiratory function in older adults with COPD

Chronic obstructive pulmonary disease (COPD) is a chronic intractable lung disease. To investigate the therapeutic effect, older adult patients were subjected to aerobic exercise and respiratory rehabilitation (diaphragmatic breathing) for six months. At the end of six-month intervention, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), 6-minute walking distance (6 MWD), and patient activation measure scores increased; St. George's respiratory questionnaire scores and disease impact score decreased; and PaCO₂ and PaO₂ were significantly improved in both groups, particularly in the experimental group. In addition, FEV1, FEV1/FVC, 6 MWD, blood gas levels, quality of life, and self-care ability in the experimental group were significantly improved compared with those in the control group, and the improvements were significantly greater in male, younger, and less diseased patients. Our study demonstrated that aerobic exercise combined with diaphragmatic breathing significantly improves respiratory function and quality of life in older adult patients.

Management of Acute Exacerbations of Chronic Obstructive Pulmonary Disease in the ICU: An Observational Study From the OUTCOMEREA Database, 1997-2018

OBJECTIVES

Our aim was to describe changes in the management of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) by ICUs and patient outcomes.

DESIGN

We extracted data from the OutcomeRea database concerning patients admitted for AECOPD between 1997 and 2018. We analyzed trends in the use of ventilatory support, corticosteroid therapy, antibiotic therapy, and patient survival.

SETTING

ICUs at 32 French sites.

PATIENTS

One thousand eight hundred sixteen patients in the database had a diagnosis of AECOPD.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Over time, there was a reduction in the prescription of corticosteroids and antibiotics. In a time-series analysis, these changes in practice were not linked with ICU mortality. The proportion of patients treated with invasive mechanical ventilation (IMV) also gradually declined (from 51% between 1997 and 2002 to 35% between 2013 and 2018) with an association between decrease in IMV use and reduction in ICU mortality in a time series analysis. Rates of noninvasive ventilation (NIV) failure decreased with an increase in NIV use to support weaning from IMV. There was a reduction in the median ICU length of stay (from 8 d in 1997-2002 to 4 d in 2013-2018) and in the median total duration of hospitalization (from 23 d in 1997-2002 to 14 d in 2013-2018). We observed an improvement in prognosis, with decreases in overall hospital mortality (from 24% between 1997 and 2002 to 15% between 2013 and 2018), ICU mortality (from 14% between 1997 and 2002 to 10% between 2013 and 2018), and 90-day mortality (from 41% between 1997 and 2002 to 22% between 2013 and 2018).

CONCLUSIONS

The length of stay and mortality of patients with AECOPD admitted to ICUs has decreased over the last 20 years, with a wider use of NIV and a reduction in antibiotic and corticosteroid prescriptions.

Timing of Treatment Outcomes and Risk Factors for Failure of BPAP in Patients Hospitalized for COPD Exacerbation

BACKGROUND

Patients hospitalized for COPD exacerbation have an increased risk of mortality, particularly among those who fail bi-level positive airway pressure (BPAP) for hypercapnic respiratory failure subsequently requiring invasive mechanical ventilation. Therefore, we sought to investigate the treatment course of BPAP and factors associated with BPAP treatment failure.

METHODS

We performed a retrospective cohort study using real-world evidence to investigate subjects with COPD who were treated with BPAP during a hospitalization for COPD exacerbation. Treatment outcomes were defined within 7 d from BPAP initiation as either failure, persistent, or success. Failure was defined as death or progression to invasive ventilation. Persistent was defined as receiving BPAP during hospital day 7. Success was defined as liberation from BPAP prior to hospital day 7 and not meeting criteria for failure. Unadjusted multinomial logistic regression models were used to examine the association between BPAP treatment outcomes and 17 recipient characteristics.

RESULTS

Among the 427 clinical encounters, 78% were successful, 10% were persistent, and 12% experienced failure. The median time to failure and success was 8 h and 16 h, respectively. Increasing age, body mass index (BMI), bicarbonate level, and creatinine level were significantly associated with either BPAP treatment failure, persistent treatment, or both.

CONCLUSIONS

The first 8 h following initiation of BPAP is a critical time period where patients are at high risk for life-threatening decompensation. Careful consideration should be given to increasing age, BMI, bicarbonate level, and creatinine level as these factors were associated with BPAP treatment failure or persistent treatment.

High-flow nasal cannula versus non-invasive ventilation for acute hypercapnic respiratory failure in adults: a systematic review and meta-analysis of randomized trials

Background

Non-invasive ventilation (NIV) with bi-level positive pressure ventilation is a first-line intervention for selected patients with acute hypercapnic respiratory failure. Compared to conventional oxygen therapy, NIV may reduce endotracheal intubation, death, and intensive care unit length of stay (LOS), but its use is often limited by patient tolerance and treatment failure. High-flow nasal cannula (HFNC) is a potential alternative treatment in this patient population and may be better tolerated.

Research question

For patients presenting with acute hypercapnic respiratory failure, is HFNC an effective alternative to NIV in reducing the need for intubation?

Methods

We searched EMBASE, MEDLINE, and the Cochrane library from database inception through to October 2021 for randomized clinical trials (RCT) of adults with acute hypercapnic respiratory failure assigned to receive HFNC or NIV. The Cochrane risk-of-bias tool for randomized trials was used to assess risk of bias. We calculated pooled relative risks (RR) for dichotomous outcomes and mean differences (MD) for continuous outcomes, with corresponding 95% confidence intervals (CI) using a random-effects model.

Results

We included eight RCTs (n = 528) in the final analysis. The use of HFNC compared to NIV did not reduce the risk of our primary outcome of mortality (RR 0.86, 95% CI 0.48–1.56, low certainty), or our secondary outcomes including endotracheal intubation (RR 0.80, 95% CI 0.46–1.39, low certainty), or hospital LOS (MD − 0.82 days, 95% CI − 1.83–0.20, high certainty). There was no difference in change in partial pressure of carbon dioxide between groups (MD − 1.87 mmHg, 95% CI − 5.34–1.60, moderate certainty).

Interpretation

The current body of evidence is limited in determining whether HFNC may be either superior, inferior, or equivalent to NIV for patients with acute hypercapnic respiratory failure given imprecision and study heterogeneity. Further studies are needed to better understand the effect of HFNC on this population.

Factors and Outcomes Associated with Failed Noninvasive Positive Pressure Ventilation in Patients with Acute Respiratory Failure

Background

The decision guild for non-invasive positive pressure ventilation (NPPV) application in acute respiratory failure (ARF) patients still needs to work out.

Methods

Adult patients with acute hypoxemic or hypercapnic respiratory failure were recruited and treated with NPPV or primary invasive mechanical ventilation (IMV). Patients’ characteristic and clinical outcomes were recorded. Logistic regression models were used to estimate the adjusted odds ratio (aOR) and 95% confidence intervals for baseline characteristics and clinical outcomes. Subgroup analyses by reason behind successful NPPV were conducted to ascertain if any difference could influence the outcome.

Results

A total of 4525 ARF patients were recruited in our facility between year 2015 and 2017. After exclusion, 844 IMV patients, 66 patients with failed NPPV, and 74 patients with successful NPPV were enrolled. Statistical analysis showed APACHE II score (aOR = 0.93), time between admission and start NPPV (aOR = 0.92), and P/F ratio (aOR = 1.04) were associated with successful NPPV. When comparing with IMV patients, failed NPPV patients displayed a significantly lower APACHE II score, higher Glasgow Coma Scale, longer length of stay in hospital, longer duration of invasive ventilation, RCW/Home ventilator, and some comorbidities.

Conclusion

APACHE II score, time between admission and start NPPV, and PaO2 can be predictors for successful NPPV. The decision of NPPV application is critical as ARF patients with failed NPPV have various worse outcomes than patients receiving primary IMV.

Predictors of Respiratory Support Use in Emergency Department Patients With COVID-19-Related Respiratory Failure

BACKGROUND

Given the known downstream implications of choice of respiratory support on patient outcomes, all factors influencing these decisions, even those not limited to the patient, warrant close consideration. We examined the effect of emergency department (ED)-specific system factors, such as work load and census, on the use of noninvasive versus invasive respiratory support.

METHODS

We conducted a multi-center retrospective cohort study of all adult subjects with severe COVID-19 requiring an ICU admission from 5 EDs within a single urban health care system. Subject demographics, severity of illness, and the type of respiratory support used were obtained. Using continuous measures of ED census, boarding, and active management, we estimated ED work load for each subjects' ED stay. The subjects were categorized by type(s) of respiratory support used: low-flow oxygen, noninvasive respiratory support (eg, noninvasive ventilation [NIV] and/or high-flow nasal cannula [HFNC]), invasive mechanical ventilation, or invasive mechanical ventilation after trial of NIV/HFNC. We used multivariable logistic regression to examine system factors associated with the type of respiratory support used in the ED.

RESULTS

A total of 634 subjects were included. Of these, 431 (70.0%) were managed on low-flow oxygen alone, 108 (17.0%) on NIV/HFNC, 54 (8.5%) on invasive mechanical ventilation directly, and 41 (6.5%) on NIV/HFNC prior to invasive mechanical ventilation in the ED. Higher severity of illness and underlying lung disease increased the odds of requiring invasive mechanical ventilation compared to low-flow oxygen (odds ratio 1.05 [95% CI 1.03-1.07] and odds ratio 3.47 [95% CI 1.37-8.78], respectively). Older age decreased odds of being on invasive mechanical ventilation compared to low-flow oxygen (odds ratio 0.96 [95% CI 0.94-0.99]). As ED work load increased, the odds for subjects to be managed initially with NIV/HFNC prior to invasive mechanical ventilation increased 6-8-fold.

CONCLUSIONS

High ED work load was associated with higher odds on HFNC/NIV prior to invasive mechanical ventilation.

Is PM2.5 associated with emergency department visits for mechanical ventilation in acute exacerbation of chronic obstructive pulmonary disease?

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) can have recurrent exacerbations and acute respiratory failure (ARF) triggered by particulate matter with a diameter of ≤2.5 μm (PM_2.5). To prevent ventilator shortages, this study investigated the short-term association between PM_2.5 concentration and emergency department visits (EDVs) among patients with acute exacerbation of COPD (AECOPD) requiring mechanical ventilation (MV).

METHODS

We conducted a time-series study to predict the PM_2.5 concentration and number of ventilators needed. Daily counts of EDVs among AECOPD patients requiring ventilation from 2015 to 2019 were obtained from a hospital. Generalized linear models extending Poisson regression were used to explore the association of AECOPD with PM_2.5 after controlling for the time trend, seasonal variations, and meteorological variables.

RESULTS

Eight hundred seventy-five AECOPD patients receiving MV were recorded, of whom 734 received noninvasive ventilation and 141 received invasive ventilatory support. EDVs for AECOPD patients with ARF significantly increased by 3.5% (95% confidence interval [CI]: 2.51%-4.42%) per 10 μg m^-3 increase in PM_2.5 concentration. Among seasons, PM_2.5 concentration had the strongest effect on AECOPD patients with ARF in spring (<24.5 °C), with a 1.64% (95% CI: -0.56% to 3.83%) increase in admissions per 10 μg m^-3 increase in same-day PM_2.5 concentration. The interquartile range increase of 20 μg m^-3 between winter and spring was associated with an average EDV increase of 48.66%.

CONCLUSION

This is the first study to predict the number of ventilators required by calculating quantitative estimates of the short-term effects of PM_2.5 on EDVs for AECOPD patients with ARF. Adverse effects of PM_2.5 on AECOPD patients requiring MV are evident, especially in the spring. Establishing protective standards and reducing the PM_2.5 concentration to below various thresholds are urgently needed.

Impact of HACOR Score on Noninvasive Ventilation Failure in Non-COPD Patients with Acute-on-Chronic Respiratory Failure

Background

A rating scale that takes into account heart rate, acidosis, consciousness, oxygenation, and respiratory rate (the HACOR score) has been used to predict noninvasive ventilation (NIV) failure in patients with chronic obstructive pulmonary disease (COPD). However, the HACOR score has not been used to predict NIV failure in non-COPD patients with acute-on-chronic respiratory failure.

Methods

This study was performed in the respiratory intensive care unit of a teaching hospital. Data had been collected prospectively between June 2011 and January 2019. We enrolled non-COPD patients who received NIV due to acute-on-chronic respiratory failure, pH < 7.35, and PaCO₂ >45 mmHg. NIV failure was defined as requiring intubation or dying during NIV. The HACOR score was determined at initiation and after 1-2, 12, and 24 h of NIV. Scores can range from 0 to 27, with higher scores indicating a higher risk of NIV failure.

Results

A total of 148 patients were enrolled in the study, 52 with sleep apnea-hypopnea syndrome, 34 with chronic thoracic sequelae, 31 with bronchiectasis, 14 with chest wall deformity, 5 with obesity-hypoventilation syndrome, and 12 with other conditions. Of the patients, 19 (13%) experienced NIV failure. From initiation to 24 h of NIV, the HACOR scores of patients who experienced NIV failure were much higher than those of patients who received successful NIV. The area under the receiver operating characteristic curve was 0.69, 0.91, 0.91, and 0.94 when the HACOR score was tested at initiation and after 1-2, 12, and 24 h of NIV, respectively. To obtain the best sensitivity and specificity, the cutoff value at initiation was 7 with a sensitivity of 68% and a specificity of 61%. After 1-2 h of NIV, it was 5 with a sensitivity of 90% and a specificity of 85%. After 12 h of NIV, it was 4 with a sensitivity of 82% and a specificity of 91%. After 24 h of NIV, it was 2 with a sensitivity of 100% and a specificity of 76%.

Conclusions

The HACOR score has high sensitivity and specificity for predicting NIV failure among non-COPD patients who receive NIV due to acute-on-chronic respiratory failure with respiratory acidosis.

The predictive ability of SAPS II, APACHE II, SAPS III, and APACHE IV to assess outcome and duration of mechanical ventilation in respiratory intensive care unit

Objectives:

The objective is to determine utility of SAPS II, APACHE II, SAPS III, and APACHE IV scoring system in assessing outcome in mechanically ventilated patients in respiratory intensive care unit and to predict duration of mechanical ventilation (MV).

Materials and Methods:

A prospective observational study where 83 mechanically ventilated patients were grouped into Group 1 (n₁ = 40, NIV) and Group 2 (n₂ = 43, Invasive ventilation) was conducted. SAPS II, APACHE II, SAPS III, and APACHE IV scores based predicted mortality (PM) were collected at day 1, and day 3. Outcomes (on day 7) were grouped into negative and positive. (NIV-negative outcome = Home NIV, intubation or death; positive outcome = NIV free. Invasive group-positive outcome = Extubation; negative outcome = Death). Binary logistic regression was applied to predict duration of MV (> or < 5 days).

Results:

The data were analyzed using SPSS version 17.0 trials comparisons of PM on day 1 with SAPS II (P < 0.05) and APACHE IV (P < 0.007) were significant predictors of clinical outcomes in Group 1 where as in Group 2, none of the system could predict significantly. On day 3, Group 1 analysis revealed SAPS II (P < 0.002), SAPS III (P < 0.03), and APACHE IV (P < 0.004) based PM as significant predictors of outcome. APACHE II (P < 0.05) and APACHE IV (P < 0.02) PM were significant in Group 2. On day 3, APACHE IV could significantly predict (P < 0.05) duration of MV (>5 or < 5) while A-a gradient (P < 0.09) predicted poorly in Group 1. In Group 2, APACHE IV was a poor predictor (P < 0.09). Two full logistic regression models were also formulated for both the groups.

Conclusion:

Study concludes that day 3 severity scores are more significant predictors of outcome and duration. APACHE IV scoring system was found more effective than other systems, not only significantly differentiating outcomes of MV but also predicting duration of NIV.

In vitro characterization of PrismaLung+: a novel ECCO2R device

BACKGROUND

Invasive mechanical ventilation is lifesaving in the setting of severe acute respiratory failure but can cause ventilation-induced lung injury. Advances in extracorporeal CO₂ removal (ECCO₂R) technologies may facilitate more protective lung ventilation in acute respiratory distress syndrome, and enable earlier weaning and/or avoid invasive mechanical ventilation entirely in chronic obstructive pulmonary disease exacerbations. We evaluated the in vitro CO₂ removal capacity of the novel PrismaLung+ ECCO₂R device compared with two existing gas exchangers.

METHODS

The in vitro CO₂ removal capacity of the PrismaLung+ (surface area 0.8 m², Baxter) was compared with the PrismaLung (surface area 0.35 m², Baxter) and A.L.ONE (surface area 1.35 m², Eurosets) devices, using a closed-loop bovine blood-perfused extracorporeal circuit. The efficacy of each device was measured at varying pCO₂ inlet (p_inCO₂) levels (45, 60, and 80 mmHg) and blood flow rates (Q_B) of 200-450 mL/min; the PrismaLung+ and A.L.ONE devices were also tested at a Q_B of 600 mL/min. The amount of CO₂ removed by each device was assessed by measurement of the CO₂ infused to maintain circuit equilibrium (CO₂ infusion method) and compared with measured CO₂ concentrations in the inlet and outlet of the CO₂ removal device (blood gas analysis method).

RESULTS

The PrismaLung+ device performed similarly to the A.L.ONE device, with both devices demonstrating CO₂ removal rates ~ 50% greater than the PrismaLung device. CO₂ removal rates were 73 ± 4.0, 44 ± 2.5, and 72 ± 1.9 mL/min, for PrismaLung+, PrismaLung, and A.L.ONE, respectively, at Q_B 300 mL/min and p_inCO₂ 45 mmHg. A Bland-Altman plot demonstrated that the CO₂ infusion method was comparable to the blood gas analysis method for calculating CO₂ removal. The resistance to blood flow across the test device, as measured by pressure drop, varied as a function of blood flow rate, and was greatest for PrismaLung and lowest for the A.L.ONE device.

CONCLUSIONS

The newly developed PrismaLung+ performed more effectively than PrismaLung, with performance of CO₂ removal comparable to A.L.ONE at the flow rates tested, despite the smaller membrane surface area of PrismaLung+ versus A.L.ONE. Clinical testing of PrismaLung+ is warranted to further characterize its performance.

Update on extracorporeal carbon dioxide removal: a comprehensive review on principles, indications, efficiency, and complications

TECHNOLOGY

Extracorporeal carbon dioxide removal means the removal of carbon dioxide from the blood across a gas exchange membrane without substantially improving oxygenation. Carbon dioxide removal is possible with substantially less extracorporeal blood flow than needed for oxygenation. Techniques for extracorporeal carbon dioxide removal include (1) pumpless arterio-venous circuits, (2) low-flow venovenous circuits based on the technology of continuous renal replacement therapy, and (3) venovenous circuits based on extracorporeal membrane oxygenation technology.

INDICATIONS

Extracorporeal carbon dioxide removal has been shown to enable more protective ventilation in acute respiratory distress syndrome patients, even beyond the so-called "protective" level. Although experimental data suggest a benefit on ventilator induced lung injury, no hard clinical evidence with respect to improved outcome exists. In addition, extracorporeal carbon dioxide removal is a tool to avoid intubation and mechanical ventilation in patients with acute exacerbated chronic obstructive pulmonary disease failing non-invasive ventilation. This concept has been shown to be effective in 56-90% of patients. Extracorporeal carbon dioxide removal has also been used in ventilated patients with hypercapnic respiratory failure to correct acidosis, unload respiratory muscle burden, and facilitate weaning. In patients suffering from terminal fibrosis awaiting lung transplantation, extracorporeal carbon dioxide removal is able to correct acidosis and enable spontaneous breathing during bridging. Keeping these patients awake, ambulatory, and breathing spontaneously is associated with favorable outcome.

COMPLICATIONS

Complications of extracorporeal carbon dioxide removal are mostly associated with vascular access and deranged hemostasis leading to bleeding. Although the spectrum of complications may differ, no technology offers advantages with respect to rate and severity of complications. So called "high-extraction systems" working with higher blood flows and larger membranes may be more effective with respect to clinical goals.

Noninvasive Ventilation for Critically Ill Subjects With Acute Respiratory Failure in the Emergency Department

BACKGROUND

We aimed to investigate the association between noninvasive ventilation (NIV) initiated in the emergency department and patient outcomes for those requiring invasive mechanical ventilation so that we could understand the effect of extended NIV use (ie, > 4 h) prior to invasive mechanical ventilation on patient outcomes.

METHODS

We conducted a retrospective single-center cohort study at an academic tertiary care hospital center. All emergency department patients with acute respiratory failure requiring invasive mechanical ventilation and admission to the ICU within 48 h of initial presentation over a 24-month period were included.

RESULTS

Subject characteristics, ventilator parameters, and clinical course were captured via electronic query, respiratory billing data, and standardized chart abstraction. A total of 431 subjects with acute respiratory failure requiring invasive mechanical ventilation within 48 h of arrival were identified, of whom 115 (26.7%) were exposed to NIV prior to invasive mechanical ventilation, with a median duration of 4 h (interquartile range 1.9-9.3). Based on a multivariable model controlling for covariates, any NIV exposure prior to invasive mechanical ventilation was not associated with an increased odds of persistent organ dysfunction or death. However, in the subset of subjects exposed to NIV, extended NIV use (ie, > 4 h) prior to invasive mechanical ventilation was associated with increased odds of persistent organ dysfunction or death (odds ratio 4.11, 95% CI 1.51-11.19). Extended NIV use was also associated with increased odds of in-hospital mortality (odds ratio 4.02, 95% CI 1.51-10.74).

CONCLUSIONS

Although any exposure to NIV prior to invasive mechanical ventilation did not appear to affect morbidity and mortality, extended NIV use prior to invasive mechanical ventilation was associated with worse patient outcomes, suggesting a need for additional study to better understand the ramifications of duration of NIV use prior to failure on outcomes. Given this early timeframe for intervention, future studies should be collaborations between the emergency department and ICU.

Impact of Using a Novel Gastric Feeding Tube Adaptor on Patient's Comfort and Air Leaks During Non-invasive Mechanical Ventilation

INTRODUCTION

The presence of oral or naso-enteral probes during non-invasive mechanical ventilation (NIMV) increases the risk of leakage and patient discomfort. The objective of this study was to evaluate the effectiveness of a novel tube adapter for NIMV (TA-NIMV) in relation to leakage and comfort level.

METHODS

A non-randomized quasi-experimental design was performed in an adult intensive care unit of a highly complex hospital, in which patients were their own controls. We included adult patients who required NIV with oronasal mask and who simultaneously had oral or naso-enteric tubes. The interventions were as follows: every participant received two therapies, one with the TA-NIMV and one conventional therapy of NIMV (CT-NIMV). Comfort could be evaluated in 99 patients with a Glasgow Coma Scale of 15. The outcomes of interest was the average percentage of air leak and patient comfort during each intervention.

RESULTS

196 patients were included in the study during a 16-month period. The mean air leak percentage was 9.2% [standard deviation (SD), 7.7] during TA-NIMV and 32.5% (SD, 12.5) during CT-NIMV (p<0.001). 84.9% reported being comfortable or very comfortable during TA-VMNI. 66.7% Uncomfortable or Very uncomfortable during CT-NIMV (p<0.001).

CONCLUSION

Higher comfort levels and lower air leakage volume percentages were achieved using the TA-NIMV than those achieved by CT-NIMV.

Early prediction of noninvasive ventilation failure in COPD patients: derivation, internal validation, and external validation of a simple risk score

Background

Early identification of noninvasive ventilation (NIV) failure is a promising strategy for reducing mortality in chronic obstructive pulmonary disease (COPD) patients. However, a risk-scoring system is lacking.

Methods

To develop a scale to predict NIV failure, 500 COPD patients were enrolled in a derivation cohort. Heart rate, acidosis (assessed by pH), consciousness (assessed by Glasgow coma score), oxygenation, and respiratory rate (HACOR) were entered into the scoring system. Another two groups of 323 and 395 patients were enrolled to internally and externally validate the scale, respectively. NIV failure was defined as intubation or death during NIV.

Results

Using HACOR score collected at 1–2 h of NIV to predict NIV failure, the area under the receiver operating characteristic curves (AUC) was 0.90, 0.89, and 0.71 for the derivation, internal-validation, and external-validation cohorts, respectively. For the prediction of early NIV failure in these three cohorts, the AUC was 0.91, 0.96, and 0.83, respectively. In all patients with HACOR score > 5, the NIV failure rate was 50.2%. In these patients, early intubation (< 48 h) was associated with decreased hospital mortality (unadjusted odds ratio = 0.15, 95% confidence interval 0.05–0.39, p < 0.01).

Conclusions

HACOR scores exhibited good predictive power for NIV failure in COPD patients, particularly for the prediction of early NIV failure (< 48 h). In high-risk patients, early intubation was associated with decreased hospital mortality.

High flow nasal cannula oxygen therapy versus non-invasive ventilation for chronic obstructive pulmonary disease with acute-moderate hypercapnic respiratory failure: an observational cohort study

Background

High-flow nasal cannula (HFNC) oxygen therapy in acute hypoxic respiratory failure is becoming increasingly popular. However, evidence to support the use of HFNC in acute respiratory failure (ARF) with hypercapnia is limited.

Methods

Chronic obstructive pulmonary disease (COPD) patients with moderate hypercapnic ARF (arterial blood gas pH 7.25–7.35, PaCO₂>50 mmHg) who received HFNC or non-invasive ventilation (NIV) in the intensive care uint from April 2016 to March 2018 were analyzed retrospectively. The endpoint was treatment failure, defined as either invasive ventilation, or a switch to the other study treatment (NIV for patients in the NFNC group, and vice-versa), and 28-day mortality.

Results

Eighty-two COPD patients (39 in the HFNC group and 43 in the NIV group) were enrolled in this study. The mean age was 71.8±8.2 and 54 patients (65.9%) were male. The treatment failed in 11 out of 39 patients with HFNC (28.2%) and in 17 of 43 patients with NIV (39.5%) (P=0.268). No significant differences were found for 28-day mortality (15.4% in the HFNC group and 14% in the NIV group, P=0.824). During the first 24 hrs of treatment, the number of nursing airway care interventions in the HFNC group was significantly less than in the NIV group, while the duration of device application was significantly longer in the HFNC group (all P<0.05). Skin breakdown was significantly more common in the NIV group (20.9% vs 5.1%, P<0.05).

Conclusion

Among COPD patients with moderate hypercarbic ARF, the use of HFNC compared with NIV did not result in increased rates of treatment failure, while there were fewer nursing interventions and skin breakdown episodes reported in the HFNC group.

Acute non-invasive ventilation - getting it right on the acute medical take

Non-invasive ventilation (NIV) given to the right patient, in the right setting, in the right way and at the right time improves outcomes. However, national audits reveal poor practice in patient selection, clinical judgement, treatment initiation and availability of trained staff. NIV is indicated for persistent acute hypercapnic respiratory failure (AHRF) with acidosis after usual medical management in chronic obstructive pulmonary disease (COPD) exacerbation and even without acidosis in neuromuscular disorders or other restrictive conditions eg obesity hypoventilation or kyphoscoliosis. Having trained staff in a suitable environment with adequate equipment are keys to its success, along with close monitoring. A plan should be put in place at the time of initiating NIV about the ceiling of care, eg escalation to intubation or palliation, if the patient is not improving with NIV. Early NIV failure is most likely due to technical issues, such as inadequate pressures or mask leak, while late failure is usually the consequence of advanced disease. Any presentation with AHRF is a poor prognostic indicator and outpatient respiratory follow-up is indicated following discharge. For selected patients with COPD who remain hypercapnic 2 weeks after an exacerbation, domiciliary NIV can reduce admissions and improve survival. For patients with neuromuscular disorders or kyphoscoliosis a presentation with AHRF almost always indicates the need for domiciliary NIV.

The v-DECAF score can predict 90-day all-cause mortality in patients with COPD exacerbation requiring invasive mechanical ventilation

INTRODUCTION

The DECAF score is a simple and effective tool for predicting mortality in patients hospitalized with acute exacerbations of chronic obstructive pulmonary disease (AECOPD); however, the DECAF score has not been validated in AECOPD patients requiring invasive mechanical ventilation (IMV). We devised the ventilator (v)-DECAF score, in which "anemia" replaces "acidaemia," for use in AECOPD patients requiring IMV. The objective of this study was to compare the predictive efficacy of the v-DECAF score and the DECAF score.

METHODS

This study prospectively recruited 112 consecutive AECOPD patients requiring IMV from a single center. The clinical endpoint was 90-day all-cause mortality. Demographic and clinical data were recorded, as well as APACHE II, GCS, CURB-65, BAP-65 and DECAF scores, and the newly devised v-DECAF score. The discriminatory value of the scoring systems in predicting 90-day all-cause mortality was determined using the area under the receiver operating characteristic (AUROC) curve.

RESULTS

In multivariate logistic regression analysis, the v-DECAF score was an independent predictor of 90-day all-cause mortality (odds ratio 3.004, 95% CI 1.658-5.445, P < 0.001). The AUROC of the v-DECAF and DECAF scores were 0.852 (95% CI 0.766-0.938) and 0.777 (95%CI: 0.676-0.878), respectively. The v-DECAF score had a better predictive value for 90-day all-cause mortality compared to the DECAF score (Z = 2.338, P = 0.019).

CONCLUSION

The v-DECAF score had good discriminatory power in predicting 90-day all-cause mortality in AECOPD patients requiring IMV.

Specialist emergency care and COPD outcomes

INTRODUCTION

In exacerbation of chronic obstructive pulmonary disease (ECOPD) requiring hospitalisation greater access to respiratory specialists improves outcome, but is not consistently delivered. The UK National Confidential Enquiry into Patient Outcome and Death 2015 enquiry showed over 25% of patients receiving acute non-invasive ventilation (NIV) for ECOPD died in hospital. On 16 June 2015 the Northumbria Specialist Emergency Care Hospital (NSECH) opened, introducing 24/7 specialty consultant on-call, direct admission from the emergency department to specialty wards and 7-day consultant review. A Respiratory Support Unit opened for patients requiring NIV. Before NSECH the NIV service included mandated training and competency assessment, 24/7 single point of access, initiation of ventilation in the emergency department, a door-to-mask time target, early titration of ventilation pressures and structured weaning. Pneumonia or hypercapnic coma complicating ECOPD have never been considered contraindications to NIV. After NSECH staff-patient ratios increased, the NIV pathway was streamlined and structured daily multidisciplinary review introduced. We compared our outcomes with historical and national data.

METHODS

Patients hospitalised with ECOPD between 1 January 2013 and 31 December 2016 were identified from coding, with ventilation status and radiological consolidation confirmed from records. Age, gender, admission from nursing home, consolidation, revised Charlson Index, key comorbidities, length of stay, and inpatient and 30-day mortality were captured. Outcomes pre-NSECH and post-NSECH opening were compared and independent predictors of survival identified via logistic regression.

RESULTS

There were 6291 cases. 24/7 specialist emergency care was a strong independent predictor of lower mortality. Length of stay reduced by 1  day, but 90-day readmission rose in both ventilated and non-ventilated patients.

CONCLUSION

Provision of 24/7 respiratory specialist emergency care improved ECOPD survival and shortened length of stay for both non-ventilated and ventilated patients. The potential implications in respect to service design and provision nationally are substantial and challenging.

Predictive value of neutrophil to lymphocyte ratio in patients with acute exacerbation of chronic obstructive pulmonary disease

OBJECTIVE

This study aimed to determine the predictive value of the neutrophil to lymphocyte ratio (NLR) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

METHODS

A retrospective study was conducted from March 2012 to May 2016 in Fuxing Hospital, Capital University of Medical Science. We collected 906 cases (525 males, 381 females, mean age 81.86±9.75 years) diagnosed with AECOPD. The NLR was calculated from their white blood cell (WBC), neutrophil (NEU), and lymphocyte (LYM) counts, which were obtained at laboratory examination.

RESULT

After treatment, 698 patients with AECOPD improved. The NLR was higher at admission (6.89±6.82) than after treatment (4.19±5.11) (P = 0.000). The area under the receiver operating characteristic curve (AUC) of the NLR for predicting the 28-day mortality rate was 0.737. Using 8.130 as the critical NLR value, the sensitivity was 60.5%, and the specificity was 74.8%. The AUC of the NLR for predicting the frequency of the need for invasive mechanical ventilation was 0.732. Using 10.345 as the critical NLR value, the sensitivity was 54.3%, and the specificity was 84.8%. The AUC of WBC, NEU and LYM for predicting 28-day mortality and the need for invasive mechanical ventilation in these patients were all less than 0.7. An increased NLR was an independent risk factor for 28-day mortality (OR = 1.067, 95% CI = 1.039 to 1.095, P = 0.000), intensive care unit occupancy (OR = 1.046, 95% CI = 1.023 to 1.068, P = 0.000), and the need for invasive mechanical ventilation (OR = 1.042, 95% CI = 1.019 to 1.066, P = 0.000). Compared with those patients without comorbidities, patients with renal dysfunction or upper gastrointestinal bleeding had an increased risk of death within 28 days (OR = 3.102, 95% CI = 1.525 to 6.312; OR = 4.598, 95% CI = 1.825 to 11.583, respectively), ICU admission (OR = 2.228, 95% CI = 1.286 to 3.860; OR = 3.103, 95% CI = 1.402 to 6.866, respectively), and the need for invasive mechanical ventilation (OR = 3.572, 95% CI = 1.822 to 7.000; OR = 4.279, 95% CI = 1.823 to 10.045, respectively).

CONCLUSION

In patients with AECOPD, the accuracy of the NLR for predicting the 28-day mortality rate and frequency of the need for mechanical ventilation was significantly higher than the accuracy of WBC, NEU and LYM counts. AECOPD patients with an NLR≥8.130 had higher 28-day mortality rate, while those with an NLR ≥10.345 were more likely to need invasive mechanical ventilation.

Prolonged stay predictors in patients admitted with chronic obstructive pulmonary disease acute exacerbation

Objectives:

The study aimed to identify the factors related to prolonged stay in those patients admitted with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) to our hospital.

Methods:

We conducted a retrospective study by reviewing the medical records of all patients admitted with AECOPD to the University Hospital Complex of Santiago de Compostela in 2007 and 2008. To identify variables independently associated with length of stay, we conducted a logistic regression including those variables which proved to be significant in the univariate analysis.

Results:

Six hundred and sixty-one patients were assessed; 76.6% were male and the mean age was 74.5 years (standard deviation [SD]: 11.48). The mean stay was 11.9 days (SD: 8) and 24% of all patients required prolonged stay. Factors associated with prolonged mean stay in multivariate analysis were admission to the Intensive Care Unit (odds ratio [OR], 14.7), hospitalization by internal medicine (OR, 2.1), and use of noninvasive mechanical ventilation (OR, 1.75).

Conclusions:

Prolonged stay in AECOPD is primarily related to the unit patients are admitted to, and to the need for more intensive care.

Daily use of extracorporeal CO2 removal in a critical care unit: indications and results

Background

While outcome improvement with extracorporeal CO₂ removal (ECCO₂R) is not demonstrated, a strong pathophysiological rational supports its use in the setting of acute respiratory distress syndrome (ARDS) and COPD exacerbation. We aimed to describe our single-center experience of ECCO₂R indications and outcome.

Methods

Patients treated with ECCO₂R in our medial ICU, from March 2014 to November 2017, were retrospectively enrolled. Primary end point was evolution of ventilator settings during the two first days following ECCO₂R start.

Results

Thirty-three patients received ECCO₂R. Seventeen were managed with Hemolung®, 10 with Prismalung®, 4 with ILA®, and 2 with Cardiohelp®. Indications for ECCO₂R were mild or moderate ARDS (n = 16), COPD exacerbation (n = 11), or uncontrolled hypercapnia due to other causes (n = 6). Four patients were not intubated at the time of ECCO₂R start. Median duration of ECCO₂R treatment was 7 days [5–10]. In ARDS patients, between baseline and day 2, median tidal volume and driving pressure decreased from 5.3 [4.4–5.9] mL/kg and 10 [8–15] to 3.8 [3.3–4.1] mL/kg and 9 [8–11], respectively. Prone positioning was performed in 10 of the 16 patients, without serious adverse event. In COPD patients, between baseline and day 2, median ventilation minute and PaCO2 decreased significantly from respectively 7.6 [6.6–8.7] L/min and 9.4 [8.4–10.1] kPa to 5.8 [4.9–6.2] L/min and 6 [5.3–6.8] kPa. Four out of 11 COPD patients were extubated while on ECCO₂R. Device thrombosis occurred in 5 patients (15%). Hemolysis was documented in 16 patients (48%). One patient died of intracranial hemorrhage, while on ECCO₂R. Twenty-four patients were discharged from ICU alive. Twenty-eight day mortality was 31% in ARDS, 9% in COPD patients, and 50% in other causes of refractory hypercapnic respiratory failure.

Conclusion

ECCO₂R was useful to apply ultra-protective ventilation among ARDS patients and improved PaCO₂, pH, and minute ventilation in COPD patients.

Electronic supplementary material

The online version of this article (10.1186/s40560-018-0304-x) contains supplementary material, which is available to authorized users.

Extracorporeal carbon dioxide removal in acute exacerbations of chronic obstructive pulmonary disease

Extracorporeal carbon dioxide removal (ECCO2R) has been proposed as an adjunctive intervention to avoid worsening respiratory acidosis, thereby preventing or shortening the duration of invasive mechanical ventilation (IMV) in patients with exacerbation of chronic obstructive pulmonary disease (COPD). This review will present a comprehensive summary of the pathophysiological rationale and clinical evidence of ECCO2R in patients suffering from severe COPD exacerbations.

Variability in Tidal Volume Affects Lung and Cardiovascular Function Differentially in a Rat Model of Experimental Emphysema

In experimental elastase-induced emphysema, mechanical ventilation with variable tidal volumes (V_T) set to 30% coefficient of variation (CV) may result in more homogenous ventilation distribution, but might also impair right heart function. We hypothesized that a different CV setting could improve both lung and cardiovascular function. Therefore, we investigated the effects of different levels of V_T variability on cardiorespiratory function, lung histology, and gene expression of biomarkers associated with inflammation, fibrogenesis, epithelial cell damage, and mechanical cell stress in this emphysema model. Wistar rats (n = 35) received repeated intratracheal instillation of porcine pancreatic elastase to induce emphysema. Seven animals were not ventilated and served as controls (NV). Twenty-eight animals were anesthetized and assigned to mechanical ventilation with a V_T CV of 0% (BASELINE). After data collection, animals (n = 7/group) were randomly allocated to V_T CVs of 0% (VV₀); 15% (VV₁₅); 22.5% (VV_22.5); or 30% (VV₃₀). In all groups, mean V_T was 6 mL/kg and positive end-expiratory pressure was 3 cmH₂O. Respiratory system mechanics and cardiac function (by echocardiography) were assessed continuously for 2 h (END). Lung histology and molecular biology were measured post-mortem. VV_22.5 and VV₃₀ decreased respiratory system elastance, while VV₁₅ had no effect. VV₀, VV₁₅, and VV_22.5, but not VV₃₀, increased pulmonary acceleration time to pulmonary ejection time ratio. VV_22.5 decreased the central moment of the mean linear intercept (D2 of Lm) while increasing the homogeneity index (1/β) compared to NV (77 ± 8 μm vs. 152 ± 45 μm; 0.85 ± 0.06 vs. 0.66 ± 0.13, p < 0.05 for both). Compared to NV, VV₃₀ was associated with higher interleukin-6 expression. Cytokine-induced neutrophil chemoattractant-1 expression was higher in all groups, except VV_22.5, compared to NV. IL-1β expression was lower in VV_22.5 and VV₃₀ compared to VV₀. IL-10 expression was higher in VV_22.5 than NV. Club cell protein 16 expression was higher in VV_22.5 than VV₀. SP-D expression was higher in VV₃₀ than NV, while SP-C was higher in VV₃₀ and VV_22.5 than VV_0. In conclusion, VV_22.5 improved respiratory system elastance and homogeneity of airspace enlargement, mitigated inflammation and epithelial cell damage, while avoiding impairment of right cardiac function in experimental elastase-induced emphysema.

Evidence-based Utilization of Noninvasive Ventilation and Patient Outcomes

RATIONALE

Strong evidence supports use of noninvasive ventilation (NIV) for patients with respiratory distress from chronic obstructive pulmonary disease and heart failure (strong evidence conditions [SECs]). Despite unclear benefits of NIV for other causes of acute respiratory failure, utilization for conditions with weaker evidence is increasing, despite evidence demonstrating higher mortality for patients who suffer NIV failure (progression from NIV to invasive mechanical ventilation [IMV])) compared with being treated initially with IMV.

OBJECTIVES

To determine the association of hospital variation in evidence-based utilization of NIV with patient outcomes.

METHODS

Using the California State Inpatient Database 2011, we identified adult patients who received NIV. Patients were considered to have an SEC for NIV if they had an acute exacerbation of chronic obstructive pulmonary disease or heart failure. We used multivariable hierarchical logistic regression to determine the association between hospital rates of NIV use for SECs and patient risk of NIV failure (need for IMV after NIV).

RESULTS

Among 22,706 hospitalizations with NIV as the initial ventilatory strategy, 6,820 (30.0%) had SECs. Patients with SECs had lower risk of NIV failure than patients with weak evidence conditions (8.1 vs. 18.2%, P < 0.0001). Regardless of underlying diagnosis, patients admitted to hospitals with greater use of NIV for SECs had lower risk of NIV failure (Quartile 4 vs. Quartile 1 adjusted odds ratio = 0.62; 95% CI = 0.49-0.80). Even patients without an SEC benefited from admission to hospitals that used NIV more often for patients with SECs (Quartile 4 vs. Quartile 1 adjusted odds ratio for NIV failure = 0.68; 95% CI = 0.52-0.88).

CONCLUSIONS

Most patients who received NIV did not have conditions with strong supporting evidence for its use with wide institutional variation in patient selection for NIV. Surprisingly, we found that all patients, even those without an SEC, benefited from admission to hospitals with greater evidence-based utilization of NIV, suggesting a "hospital effect" that is synergistic with patient selection.

Hospital Noninvasive Ventilation Case Volume and Outcomes of Acute Exacerbations of Chronic Obstructive Pulmonary Disease

RATIONALE

Higher hospital case volume may produce local expertise ("practice makes perfect"), resulting in better patient outcomes. Associations between hospital noninvasive ventilation (NIV) case volume and outcomes for patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) are unclear.

OBJECTIVES

To determine associations between total hospital NIV case volume for all indications and NIV failure and hospital mortality among patients with acute exacerbations of COPD.

METHODS

Using the 2011 California State Inpatient Database and multivariable hierarchical logistic regression, we calculated hospital-level risk-adjusted rates for NIV failure (progression from NIV to invasive mechanical ventilation) and hospital mortality among patients with acute exacerbations of COPD.

MEASUREMENTS AND MAIN RESULTS

We identified 37,516 hospitalizations for acute exacerbations of COPD in 252 California hospitals in 2011. Total hospital NIV use for all indications ranged from 2 to 565 cases (median, 64; interquartile range, 96). Hospital NIV failure rates for acute exacerbations of COPD ranged from 3.7 to 31.3% (median, 8.5%; interquartile range, 4.2). At the hospital level, higher total hospital NIV case volume was weakly associated with higher hospital NIV failure rates for acute exacerbations of COPD (r = 0.13; P = 0.03). Higher hospital NIV failure rates were weakly associated with higher hospital mortality rates for acute exacerbations of COPD (r = 0.15; P = 0.02), but higher total hospital NIV case volume was not associated with hospital mortality for exacerbations of COPD (r = -0.11; P = 0.08). At the patient level, patients admitted to high-NIV versus low-NIV case-volume hospitals had greater odds of NIV failure (quartile 4 vs. quartile 1 adjusted odds ratio [aOR], 1.95; 95% confidence interval [CI], 1.12-3.40). Compared with initial treatment with invasive mechanical ventilation, NIV failure was associated with higher odds of death (aOR, 1.81; 95% CI, 1.35-2.44). However, admission to high-NIV versus low-NIV case-volume hospitals was not significantly associated with patient in-hospital mortality (quartile 4 vs. quartile 1 aOR, 0.76; 95% CI, 0.57-1.02).

CONCLUSIONS

Despite strong evidence for use of NIV in the management of acute exacerbations of COPD, we observed no significant mortality benefit and higher rates of NIV failure in high-NIV case-volume hospitals. Further investigation of patient selection and hospital factors associated with NIV failure is needed to maximize favorable patient outcomes associated with use of NIV for acute exacerbations of COPD.

[Update: acute hypercapnic respiratory failure]

BACKGROUND

Hypercapnic respiratory failure is a frequent problem in critical care and mainly affects patients with acute exacerbation of COPD (AECOPD) and acute respiratory distress syndrome (ARDS). In recent years, the usage of extracorporeal CO₂ removal (ECCO₂R) has been increasing.

OBJECTIVE

Summarizing the state of the art in the management of hypercapnic respiratory failure with special regard to the role of ECCO₂R.

METHODS

Review based on a selective literature search and the clinical and scientific experience of the authors.

RESULTS

Noninvasive ventilation (NIV) is the therapy of choice in hypercapnic respiratory failure due to AECOPD, enabling stabilization in the majority of cases and generally improving prognosis. Patients in whom NIV fails have an increased mortality. In these patients, ECCO₂R may be sufficient to avoid intubation or to shorten time on invasive ventilation; however, corresponding evidence is sparse or even missing when it comes to hard endpoints. Lung-protective ventilation according to the ARDS network is the standard therapy of ARDS. In severe ARDS, low tidal volume ventilation may result in critical hypercapnia. ECCO₂R facilitates compensation of respiratory acidosis even under "ultra-protective" ventilator settings. Yet, no positive prognostic effects could be demonstrated so far.

CONCLUSION

Optimized use of NIV and lung-protective ventilation remains standard of care in the management of hypercapnic respiratory failure. Currently, ECCO₂R has to be considered an experimental approach, which should only be provided by experienced centers or in the context of clinical trials.

Epidemiology of NIV for Acute Respiratory Failure in COPD Patients: Results from the International Surveys vs. the "Real World"

Non-invasive ventilation (NIV) has been recommended as the  first-line ventilation modality for acute respiratory failure (ARF) due to acute exacerbation of chronic obstructive pulmonary disease (AECOPD) based on strong evidence. However, everyday clinical practice may differ from findings of multiple randomized controlled trials. Physicians and respiratory therapists involved in NIV management have been queried about its utilization and effectiveness. In addition to these estimates, cohort studies and analysis of large inpatient dataset of patients with AECOPD and ARF managed with NIV have been extensively published over the last two decades. This review summarizes the perception of medical staff vs. the "real life" data about NIV use for ARF in AECOPD patients.

Noninvasive ventilation with helium-oxygen mixture in hypercapnic COPD exacerbation: aggregate meta-analysis of randomized controlled trials

When used as a driving gas during NIV in hypercapnic COPD exacerbation, a helium–oxygen (He/O₂) mixture reduces the work of breathing and gas trapping. The potential for He/O₂ to reduce the rate of NIV failure leading to intubation and invasive mechanical ventilation has been evaluated in several RCTs. The goal of this meta-analysis is to assess the effect of NIV driven by He/O₂ compared to air/O₂ on patient-centered outcomes in hypercapnic COPD exacerbation. Relevant RCTs were searched using standard procedures. The main endpoint was the rate of NIV failure. The effect size was computed by a fixed-effect model, and estimated as odds ratio (OR) with 95% confidence interval (CI). Additional endpoints were ICU mortality, NIV-related side effects, and the length and costs of ICU stay. Three RCTs fulfilled the selection criteria and enrolled a total of 772 patients (386 patients received He/O₂ and 386 received air/O₂). Pooled analysis showed no difference in the rate of NIV failure when using He/O₂ mixture compared to air/O₂: 17 vs 19.7%, respectively; OR 0.84, 95% CI 0.58–1.22; p = 0.36; I² for heterogeneity = 0%, and no publication bias. ICU mortality was also not different: OR 0.8, 95% CI 0.45–1.4; p = 0.43; I² = 5%. However, He/O₂ was associated with less NIV-related adverse events (OR 0.56, 95% CI 0.4–0.8, p = 0.001), and a shorter length of ICU stay (difference in means = −1.07 day, 95% CI −2.14 to −0.004, p = 0.049). Total hospital costs entailed by hospital stay and NIV gas were not different: difference in means = −279$, 95% CI −2052–1493, p = 0.76. Compared to air/O₂, He/O₂ does not reduce the rate of NIV failure in hypercapnic COPD exacerbation. It is, however, associated with a lower incidence of NIV-related adverse events and a shortening of ICU length of stay with no increase in hospital costs.

Trends in assisted ventilation and outcome for obstructive pulmonary disease exacerbations. A nationwide study

BACKGROUND

Non-invasive ventilation (NIV) has been used for decades in treatment of exacerbations of chronic obstructive pulmonary disease (COPD). The impact of the changing use of assisted ventilation in acute exacerbations on outcomes has not been fully elucidated and we aimed to describe these changes in the Danish population and describe their consequences for mortality.

METHODS

A register-based study was conducted of a cohort of 12,847 patients admitted for acute exacerbation of COPD (AECOPD) from 2004 through 2011, treated with invasive mechanical ventilation (IMV) or NIV for the first time. Age, sex, in-hospital mortality rates, time to death or readmission for AECOPD were established and changes over time tracked.

RESULTS

The number of admissions for AECOPD where assisted ventilation was used was 1,130 in 2004 and had increased by 145% in 2011. First time ventilations increased by 88%. This was mainly due to an increase in use of NIV accounting for 36% of the total number of assisted ventilations in 2004 and 67% in 2011. The number of IMV with or without NIV treatments remained constant. The mean age of NIV patients increased from 71.5 to 73.6 years, but remained constant at 70.0 years in IMV patients. Mortality rates both in hospital and after discharge for patients receiving NIV remained constant throughout the period. In-hospital mortality following IMV increased from 30% to 38%, but mortality after discharge remained stable.

CONCLUSION

Assisted ventilation has been increasingly used in a broader spectrum of AECOPD patients since the introduction of NIV. The changes in treatment strategies have been followed by shifts in in-hospital mortality rates following IMV.

Comparison between Variable and Conventional Volume-Controlled Ventilation on Cardiorespiratory Parameters in Experimental Emphysema

Emphysema is characterized by loss of lung tissue elasticity and destruction of structures supporting alveoli and capillaries. The impact of mechanical ventilation strategies on ventilator-induced lung injury (VILI) in emphysema is poorly defined. New ventilator strategies should be developed to minimize VILI in emphysema. The present study was divided into two protocols: (1) characterization of an elastase-induced emphysema model in rats and identification of the time point of greatest cardiorespiratory impairment, defined as a high specific lung elastance associated with large right ventricular end-diastolic area; and (2) comparison between variable (VV) and conventional volume-controlled ventilation (VCV) on lung mechanics and morphometry, biological markers, and cardiac function at that time point. In the first protocol, Wistar rats (n = 62) received saline (SAL) or porcine pancreatic elastase (ELA) intratracheally once weekly for 4 weeks, respectively. Evaluations were performed 1, 3, 5, or 8 weeks after the last intratracheal instillation of saline or elastase. After identifying the time point of greatest cardiorespiratory impairment, an additional 32 Wistar rats were randomized into the SAL and ELA groups and then ventilated with VV or VCV (n = 8/group) [tidal volume (V_T) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 3 cmH₂O, fraction of inspired oxygen (FiO₂) = 0.4] for 2 h. VV was applied on a breath-to-breath basis as a sequence of randomly generated V_T values (mean V_T = 6 mL/kg), with a 30% coefficient of variation. Non-ventilated (NV) SAL and ELA animals were used for molecular biology analysis. The time point of greatest cardiorespiratory impairment, was observed 5 weeks after the last elastase instillation. At this time point, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC)-1, amphiregulin, angiopoietin (Ang)-2, and vascular endothelial growth factor (VEGF) mRNA levels were higher in ELA compared to SAL. In ELA animals, VV reduced respiratory system elastance, alveolar collapse, and hyperinflation compared to VCV, without significant differences in gas exchange, but increased right ventricular diastolic area. Interleukin-6 mRNA expression was higher in VCV and VV than NV, while surfactant protein-D was increased in VV compared to NV. In conclusion, VV improved lung function and morphology and reduced VILI, but impaired right cardiac function in this model of elastase induced-emphysema.

Assisted ventilation in COPD - association between previous hospitalizations and mortality

BACKGROUND

In general, previous studies have shown an association between prior exacerbations and mortality in COPD, but this association has not been demonstrated in the subpopulation of patients in need of assisted ventilation. We examined whether previous hospitalizations were independently associated with mortality among patients with COPD ventilated for the first time.

PATIENTS AND METHODS

In the Danish National Patient Registry, we established a cohort of patients with COPD ventilated for the first time from 2003 to 2011 and previously medicated for obstructive airway diseases. We assessed the number of hospitalizations for COPD in the preceding year, age, sex, comorbidity, mode of ventilation, survival to discharge, and days to death beyond discharge.

RESULTS

The cohort consisted of 6,656 patients of whom 66% had not been hospitalized for COPD in the previous year, 18% once, 8% twice, and 9% thrice or more. In-hospital mortality was 45%, and of the patients alive at discharge, 11% died within a month and 39% within a year. In multivariate models, adjusted for age, sex, mode of ventilation, and comorbidity, odds ratios for in-hospital death were 1.26 (95% confidence interval [CI]: 1.11-1.44), 1.43 (95% CI: 1.19-1.72), and 1.56 (95% CI: 1.30-1.87) with one, two, and three or more hospitalizations, respectively. Hazard ratios for death after discharge from hospital were 1.32 (95% CI: 1.19-1.46), 1.76 (95% CI: 1.52-2.02), and 2.07 (95% CI: 1.80-2.38) with one, two, and three or more hospitalizations, respectively.

CONCLUSION

Preceding hospitalizations for COPD are associated with in-hospital mortality and after discharge in the subpopulation of patients with COPD with acute exacerbation treated with assisted ventilation for the first time.

Noninvasive and invasive positive pressure ventilation for acute respiratory failure in critically ill patients: a comparative cohort study

BACKGROUND

Noninvasive positive pressure ventilation (NPPV) for acute respiratory failure in the intensive care unit (ICU) is associated with a marked reduction in intubation rate, complications, hospital length of stay and mortality. Multiple studies have indicated that patients failing NPPV have worse outcomes compared with patients with successful NPPV treatment; however limited data is available on risks associated with NPPV failure resulting in (delayed) intubation and outcomes compared with initial intubation. The purpose of this study is to assess rates and predictors of NPPV failure and to compare hospital outcomes of patients with NPPV failure with those patients primarily intubated without a prior NPPV trial.

METHODS

A retrospective observational study using data from patients with acute respiratory failure admitted to the ICU in the period 2013-2014. All patients treated with NPPV were evaluated. A sample of patients who were primarily intubated was randomly selected to serve as controls for the group of patients who failed NPPV.

RESULTS

NPPV failure was recorded in 30.8% of noninvasively ventilated patients and was associated with longer ICU stay [OR, 1.16, 95% confidence interval (95% CI): 1.04-1.30] and lower survival rates (OR, 0.10, 95% CI: 0.02-0.59) compared with NPPV success. Multivariate analysis showed presence of severe sepsis at study entry, higher Simplified Acute Physiology II Score (SAPS-II) score, lower ratio of arterial oxygen tension to fraction of inspired oxygen (PF-ratio) and lower plasma glucose were predictors for NPPV failure. After controlling for potential confounders, patients with NPPV failure did not show any difference in hospital outcomes compared with patients who were primarily intubated.

CONCLUSIONS

Patients with acute respiratory failure and NPPV failure have worse outcomes compared with NPPV success patients, however not worse than initially intubated patients. An initial trial of NPPV therefore may be suitable in selected cases of patients with acute respiratory failure, since NPPV could be potentially beneficial and does not seem to result in worse outcome in case of NPPV failure compared to primary intubation. A prospective trial is warranted to confirm findings.

The role of NIV in chronic hypercapnic COPD following an acute exacerbation: the importance of patient selection?

Recently, clear benefits have been shown from long-term noninvasive ventilation (NIV) in stable chronic obstructive pulmonary disease (COPD) patients with chronic hypercapnic respiratory failure. In our opinion, these benefits are confirmed and nocturnal NIV using sufficiently high inspiratory pressures should be considered in COPD patients with chronic hypercapnic respiratory failure in stable disease, preferably combined with pulmonary rehabilitation. In contrast, clear benefits from (continuing) NIV at home after an exacerbation in patients who remain hypercapnic have not been shown. In this review we will discuss the results of five trials investigating the use of home nocturnal NIV in patients with prolonged hypercapnia after a COPD exacerbation with acute hypercapnic respiratory failure. Although some uncontrolled trials might have shown some benefits of this therapy, the largest randomized controlled trial did not show benefits in terms of hospital readmission or death. However, further studies are necessary to select the patients that optimally benefit, select the right moment to initiate home NIV, select the optimal ventilatory settings, and to choose optimal follow up programmes. Furthermore, there is insufficient knowledge about the optimal ventilatory settings in the post-exacerbation period. Finally, we are not well informed about exact reasons for readmission in patients on NIV, the course of the exacerbation and the treatment instituted. A careful follow up might probably be necessary to prevent deterioration on NIV early.