Inter-country variability over time in the mortality of mechanically ventilated patients

In-hospital mortality, comorbidities, and costs of one million mechanically ventilated patients in Germany: a nationwide observational study before, during, and after the COVID-19 pandemic

Background

Even more than hospital care in general, intensive care and mechanical ventilation capacities and its utilization in terms of rates, indications, ventilation types and outcomes vary largely among countries. We analyzed complete and nationwide data for Germany, a country with a large intensive care sector, before, during and after the COVID-19 pandemic.

Methods

Analysis of administrative claims data, provided by the German health insurance, from all hospitals for all individual patients who were mechanically ventilated between 2019 and 2022. The data included age, sex, diagnoses, length of stay, procedures (e.g., form and duration of mechanical ventilation), outcome (dead vs. alive) and costs. We included all patients who were at least 18 years old at the time of discharge from January 1st, 2019 to December 31st, 2022. Patients were grouped according to year, age group and the form of mechanical ventilation. We further analyzed subgroups of patients being resuscitated and those being COVID-19 positive (vs. negative).

Findings

During the four years, 1,003,882 patients were mechanically ventilated in 1395 hospitals. Rates per 100,000 inhabitants varied across age groups from 110 to 123 (18-59 years) to 1101-1275 (>80 years). The top main diagnoses were other forms of heart diseases, pneumonia, chronic obstructive pulmonary disease (COPD), ischemic heart diseases and cerebrovascular diseases. 43.3% (437,031/1,003,882) of all mechanically ventilated patients died in hospital with a remarkable increase in mortality with age and from 2019 to 2022 by almost 5%-points. The in-hospital mortality of ventilated COVID-19 patients was 53.7% (46,553/86,729), while it was 42.6% (390,478/917,153) in non-COVID patients. In-hospital mortality varied from 27.0% in non-invasive mechanical ventilation (NIV) only to 53.4% in invasive mechanical ventilation only cases, 59.4% with early NIV failure, 68.6% with late NIV failure, to 74.0% in patients receiving VV-ECMO and 80.0% in VA-ECMO. 17.5% of mechanically ventilated patients had been resuscitated before, of whom 78.2% (153,762/196,750) died. Total expenditure was around 6 billion Euros per year, i.e. 0.17% of the German GDP.

Interpretation

Mechanical ventilation was widely used, before, during and after the COVID-19 pandemic in Germany, reaching more than 1000 patients per 100,000 inhabitants per year in the age over 80 years. In-hospital mortality rates in this nationwide and complete cohort exceeded most of the data known by far.

Funding

This research did not receive any dedicated funding.

Severe asthma exacerbation: Changes in patient characteristics, management, and outcomes from 1997 to 2016 in 40 ICUs in the greater Paris area

Background

Despite advances in asthma treatments, severe asthma exacerbation (SAE) remains a life-threatening condition in adults, and there is a lack of data derived from adult patients admitted to intensive care units (ICUs) for SAE. The current study investigated changes in adult patient characteristics, management, and outcomes of SAE over a 20-year period in 40 ICUs in the greater Paris area.

Methods

In this retrospective observational study, admissions to 40 ICUs in the greater Paris area for SAE from January 1, 1997, to December 31, 2016 were analyzed. The primary outcome was the proportion of ICU admissions for SAE during 5-year periods. Secondary outcomes were ICU and hospital mortality, and the use of mechanical ventilation and catecholamine. Multivariate analysis was performed to assess factors associated with ICU mortality.

Results

A total of 7049 admissions for SAE were recorded. For each 5-year period, the proportion decreased over time, with SAE accounting for 2.84% of total ICU admissions (n=2841) between 1997 and 2001, 1.76% (n=1717) between 2002 and 2006, 1.05% (n=965) between 2007 and 2011, and 1.05% (n=1526) between 2012 and 2016. The median age was 46 years (interquartile range [IQR]: 32-59 years), 55.41% were female, the median Simplified Acute Physiology Score II was 20 (IQR: 13-28), and 19.76% had mechanical ventilation. The use of mechanical ventilation remained infrequent throughout the 20-year period, whereas the use of catecholamine decreased. ICU and hospital mortality rates decreased. Factors associated with ICU mortality were renal replacement therapy, catecholamine, cardiac arrest, pneumothorax, acute respiratory distress syndrome, sepsis, and invasive mechanical ventilation (IMV). Non-survivors were older, had more severe symptoms, and were more likely to have received IMV.

Conclusion

ICU admission for SAE remains uncommon, and the proportion of cases decreased over time. Despite a slight increase in symptom severity during a 20-year period, ICU and hospital mortality decreased. Patients requiring IMV had a higher mortality rate.

Mechanical ventilation in patients with idiopathic pulmonary fibrosis in Korea: a nationwide cohort study

BACKGROUND/AIMS

The prognosis of patients with idiopathic pulmonary fibrosis (IPF) and respiratory failure requiring mechanical ventilation is poor. Therefore, mechanical ventilation is not recommended. Recently, outcomes of mechanical ventilation, including those for patients with IPF, have improved. The aim of this study was to investigate changes in the use of mechanical ventilation in patients with IPF and their outcomes over time.

METHODS

This retrospective, observational cohort study used data from the National Health Insurance Service database. Patients diagnosed with IPF between January 2011 and December 2019 who were placed on mechanical ventilation were included. We analyzed changes in the use of mechanical ventilation in patients with IPF and their mortality using the Cochran- Armitage trend test.

RESULTS

Between 2011 and 2019, 1,227 patients with IPF were placed on mechanical ventilation. The annual number of patients with IPF with and without mechanical ventilation increased over time. However, the ratio was relatively stable at approximately 3.5%. The overall hospital mortality rate was 69.4%. There was no improvement in annual hospital mortality rate. The overall 30-day mortality rate was 68.7%, which did not change significantly. The overall 90-day mortality rate was 85.3%. The annual 90-day mortality rate was decreased from 90.9% in 2011 to 83.1% in 2019 (p = 0.028).

CONCLUSION

Despite improvements in intensive care and ventilator management, the prognosis of patients with IPF receiving mechanical ventilation has not improved significantly.

Maintaining moderate versus lower PEEP after cardiac surgery: a propensity-scored matched analysis

BACKGROUND

Setting positive end-expiratory pressure (PEEP) at around 5 cm H2O in the early postoperative period seems a common practice for most patients. It remains unclear if the routine application of higher levels of PEEP confers any meaningful clinical benefit for cardiac surgical patients. The aim of this study was to compare moderate versus conventional lower PEEP on patient-centered outcomes in the intensive care unit (ICU).

METHODS

This is a single-center retrospective study involving patients receiving cardiac surgery from June 2022 to May 2023. Propensity-score matching (PSM) was used to balance the baseline differences. Primary outcomes were the duration of mechanical ventilation and ICU length of stay. Secondary outcomes included PaO2/FiO2 ratio at 24 h and the need for prone positioning during ICU stay.

RESULTS

A total of 334 patients were included in the study, 102 (31%) of them received moderate PEEP (≥ 7 cm H2O) for the major time in the early postoperative period (12 h). After PSM, 79 pairs of patients were matched with balanced baseline data. The results showed that there was marginal difference in the distribution of mechanical ventilation duration (p = 0.05) and the Moderate PEEP group had a higher extubation rate at the day of T-piece trial (65 [82.3%] vs 52 [65.8%], p = 0.029). Applying moderate PEEP was also associated with better oxygenation. No differences were found regarding ICU length of stay and patients requiring prone positioning between groups.

CONCLUSION

In selective cardiac surgical patients, using moderate PEEP compared with conventional lower PEEP in the early postoperative period correlated to better oxygenation, which may have potential for earlier liberation of mechanical ventilation.

Association between mechanical power and intensive care unit mortality in Korean patients under pressure-controlled ventilation

BACKGROUND

Mechanical power (MP) has been reported to be associated with clinical outcomes. Because the original MP equation is derived from paralyzed patients under volume-controlled ventilation, its application in practice could be limited in patients receiving pressure-controlled ventilation (PCV). Recently, a simplified equation for patients under PCV was developed. We investigated the association between MP and intensive care unit (ICU) mortality.

METHODS

We conducted a retrospective analysis of Korean data from the Fourth International Study of Mechanical Ventilation. We extracted data of patients under PCV on day 1 and calculated MP using the following simplified equation: MPPCV = 0.098 ∙ respiratory rate ∙ tidal volume ∙ (ΔPinsp + positive end-expiratory pressure), where ΔPinsp is the change in airway pressure during inspiration. Patients were divided into survivors and non-survivors and then compared. Multivariable logistic regression was performed to determine association between MPPCV and ICU mortality. The interaction of MPPCV and use of neuromuscular blocking agent (NMBA) was also analyzed.

RESULTS

A total of 125 patients was eligible for final analysis, of whom 38 died in the ICU. MPPCV was higher in non-survivors (17.6 vs. 26.3 J/min, P<0.001). In logistic regression analysis, only MPPCV was significantly associated with ICU mortality (odds ratio, 1.090; 95% confidence interval, 1.029-1.155; P=0.003). There was no significant effect of the interaction between MPPCV and use of NMBA on ICU mortality (P=0.579).

CONCLUSIONS

MPPCV is associated with ICU mortality in patients mechanically ventilated with PCV mode, regardless of NMBA use.

Setting positive end-expiratory pressure in the severely obstructive patient

PURPOSE OF REVIEW

The response to positive end-expiratory pressure (PEEP) in patients with chronic obstructive pulmonary disease (COPD) requiring mechanical ventilation depends on the underlying pathophysiology. This review focuses on the pathophysiology of COPD, especially intrinsic PEEP (PEEPi) and its consequences, and the benefits of applying external PEEP during assisted ventilation when PEEPi is present.

RECENT FINDINGS

The presence of expiratory airflow limitation and increased airway resistance promotes the development of dynamic hyperinflation in patients with COPD during acute respiratory failure. Dynamic hyperinflation and the associated development of PEEPi increases work of breathing and contributes to ineffective triggering of the ventilator. In the presence of airflow limitation, application of external PEEP during patient-triggered ventilation has been shown to reduce inspiratory effort, facilitate ventilatory triggering and enhance patient-ventilator interaction. To minimize the risk of hyperinflation, it is advisable to limit the level of external PEEP during assisted ventilation after optimization of ventilator settings to about 70% of the level of PEEPi (measured during passive ventilation).

SUMMARY

In patients with COPD and dynamic hyperinflation receiving assisted mechanical ventilation, the application of low levels of external PEEP can minimize work of breathing, facilitate ventilator triggering and improve patient-ventilator interaction.

Association Between the Site of Infection and Mortality Analysis in Critically Ill Surgical Patients

Background Sepsis remains a critical global health concern, leading to a high mortality rate. Existing literature suggests a potential correlation between infection site and mortality. Mortality data from Pakistan, especially in the context of the infection site, is notably scarce. Purpose The study aimed to explore the relationship between the site of infection and clinical features in deceased septic patients in the surgical intensive care unit. Methods In this retrospective study conducted at the Aga Khan University Hospital, data from patients admitted to the surgical intensive care unit and meeting Sepsis 3 criteria over a five-year period (2016-2020) were analyzed. We analyzed the relation between the infection site and clinical characteristics using analysis of variance (ANOVA), chi-square, or Fisher's exact tests. Multivariable logistic regression models were applied using stepwise forward selection. A p-value of ≤ 0.05 was considered statistically significant. Results A total of 2472 ICU admissions were screened, out of which 170 patients were included in this study. Demographic analysis showed a predominantly male population with a mean age of 47 years. The most prevalent site of infection was the abdomen. Logistic regression analysis identified on-admission septic shock and high Acute Physiology and Chronic Health Evaluation (APACHE) II scores as significant risk factors for 48-hour mortality while colistimethate sodium usage and admission through the operating room were protective. Conclusion Our study provides a comprehensive analysis, outlining infection sites and identifying early mortality-influencing factors within our region. The distinct demographic profile, characterized by younger age, and the prevalence of abdominal infections in the Pakistani cohort contradict established medical literature. Early initiation of broad-spectrum antibiotics, coupled with prompt source control, confers a protective effect upon individuals afflicted with sepsis.

The effect of age on clinical outcomes in critically ill brain-injured patients

PURPOSE

We studied the impact of age on survival and functional recovery in brain-injured patients.

METHODS

We performed an observational cohort study of all consecutive adult patients with brain injury admitted to ICU in 8 years. To estimate the optimal cut-off point of the age associated with unfavorable outcomes (mRS 3-6), receiver operating characteristic (ROC) curve analyses were used. Multivariate logistic regression analyses were performed to identify prognostic factors for unfavorable outcomes.

RESULTS

We included 619 brain-injured patients. We identified 60 years as the cut-off point at which the probability of unfavorable outcomes increases. Patients ≥ 60 years had higher severity scores at ICU admission, longer duration of mechanical ventilation, longer ICU and hospital stays, and higher mortality. Factors identified as associated with unfavorable outcomes (mRS 3-6) were an advanced age (≥ 60 years) [Odds ratio (OR) 4.59, 95% confidence interval (CI) 2.73-7.74, p < 0.001], a low GCS score (≤ 8 points) [OR 3.72, 95% CI 1.95-7.08, p < 0.001], the development of intracranial hypertension [OR 5.52, 95% CI 2.70-11.28, p < 0.001], and intracerebral hemorrhage as the cause of neurologic disease [OR 3.87, 95% CI 2.34-6.42, p < 0.001].

CONCLUSION

Mortality and unfavorable functional outcomes in critically ill brain-injured patients were associated with older age (≥ 60 years), higher clinical severity (determined by a lower GCS score at admission and the development of intracranial hypertension), and an intracerebral hemorrhage as the cause of neurologic disease.

Adherence to protective mechanical ventilation in COVID-19 versus non-COVID-19-associated acute respiratory distress syndrome: Comparison between two prospective cohorts

OBJECTIVE

To compare adherence to protective mechanical ventilation (MV) parameters in patients with acute respiratory distress syndrome (ARDS) caused by COVID-19 with patients with ARDS from other etiologies.

DESIGN

Multiple prospective cohort study.

SETTING

Two Brazilian cohorts of ARDS patients were evaluated. One with COVID-19 patients admitted to two Brazilian intensive care units (ICUs) in 2020 and 2021 (C-ARDS, n=282), the other with ARDS-patients from other etiologies admitted to 37 Brazilian ICUs in 2016 (NC-ARDS, n=120).

PATIENTS

ARDS patients under MV.

INTERVENTIONS

None.

MAIN VARIABLES OF INTEREST

Adherence to protective MV (tidal volume ≤8mL/kg PBW; plateau pressure ≤30cmH2O; and driving pressure ≤15cmH2O), adherence to each individual component of the protective MV, and the association between protective MV and mortality.

RESULTS

Adherence to protective MV was higher in C-ARDS than in NC-ARDS patients (65.8% vs. 50.0%, p=0.005), mainly due to a higher adherence to driving pressure ≤15cmH2O (75.0% vs. 62.4%, p=0.02). Multivariable logistic regression showed that the C-ARDS cohort was independently associated with adherence to protective MV. Among the components of the protective MV, only limiting driving pressure was independently associated with lower ICU mortality.

CONCLUSIONS

Higher adherence to protective MV in patients with C-ARDS was secondary to higher adherence to limiting driving pressure. Additionally, lower driving pressure was independently associated with lower ICU mortality, which suggests that limiting exposure to driving pressure may improve survival in these patients.

Lung Ultrasound to Determine the Effect of Lower vs. Higher PEEP on Lung Aeration in Patients without ARDS-A Substudy of a Randomized Clinical Trial

BACKGROUND

Ventilation with lower positive end-expiratory pressure (PEEP) may cause loss of lung aeration in critically ill invasively ventilated patients. This study investigated whether a systematic lung ultrasound (LUS) scoring system can detect such changes in lung aeration in a study comparing lower versus higher PEEP in invasively ventilated patients without acute respiratory distress syndrome (ARDS).

METHODS

Single center substudy of a national, multicenter, randomized clinical trial comparing lower versus higher PEEP ventilation strategy. Fifty-seven patients underwent a systematic 12-region LUS examination within 12 h and between 24 to 48 h after start of invasive ventilation, according to randomization. The primary endpoint was a change in the global LUS aeration score, where a higher value indicates a greater impairment in lung aeration.

RESULTS

Thirty-three and twenty-four patients received ventilation with lower PEEP (median PEEP 1 (0-5) cm H₂O) or higher PEEP (median PEEP 8 (8-8) cm H₂O), respectively. Median global LUS aeration scores within 12 h and between 24 and 48 h were 8 (4 to 14) and 9 (4 to 12) (difference 1 (-2 to 3)) in the lower PEEP group, and 7 (2-11) and 6 (1-12) (difference 0 (-2 to 3)) in the higher PEEP group. Neither differences in changes over time nor differences in absolute scores reached statistical significance.

CONCLUSIONS

In this substudy of a randomized clinical trial comparing lower PEEP versus higher PEEP in patients without ARDS, LUS was unable to detect changes in lung aeration.

Effect of a low versus intermediate tidal volume strategy on pulmonary complications in patients at risk of acute respiratory distress syndrome-a randomized clinical trial

Introduction

There is no consensus on whether invasive ventilation should use low tidal volumes (V_T) to prevent lung complications in patients at risk of acute respiratory distress syndrome (ARDS). The purpose of this study is to determine if a low V_T strategy is more effective than an intermediate V_T strategy in preventing pulmonary complications.

Methods

A randomized clinical trial was conducted in invasively ventilated patients with a lung injury prediction score (LIPS) of >4 performed in the intensive care units of 10 hospitals in Spain and one in the United States of America (USA) from 3 November 2014 to 30 August 2016. Patients were randomized to invasive ventilation using low V_T (≤ 6 mL/kg predicted body weight, PBW) (N = 50) or intermediate V_T (> 8 mL/kg PBW) (N = 48). The primary endpoint was the development of ARDS during the first 7 days after the initiation of invasive ventilation. Secondary endpoints included the development of pneumonia and severe atelectases; the length of intensive care unit (ICU) and hospital stay; and ICU, hospital, 28- and 90-day mortality.

Results

In total, 98 patients [67.3% male], with a median age of 65.5 years [interquartile range 55-73], were enrolled until the study was prematurely stopped because of slow recruitment and loss of equipoise caused by recent study reports. On day 7, five (11.9%) patients in the low V_T group and four (9.1%) patients in the intermediate V_T group had developed ARDS (risk ratio, 1.16 [95% CI, 0.62-2.17]; p = 0.735). The incidence of pneumonia and severe atelectasis was also not different between the two groups. The use of a low V_T strategy did neither affect the length of ICU and hospital stay nor mortality rates.

Conclusions

In patients at risk for ARDS, a low V_T strategy did not result in a lower incidence of ARDS than an intermediate V_T strategy.Clinical Trial Registration: ClinicalTrials.gov, identifier NCT02070666.

Weaning Outcomes in Patients with Brain Injury

BACKGROUND

Despite the need for specific weaning strategies in neurological patients, evidence is generally insufficient or lacking. We aimed to describe the evolution over time of weaning and extubation practices in patients with acute brain injury compared with patients who are mechanically ventilated (MV) due to other reasons.

METHODS

We performed a secondary analysis of three prospective, observational, multicenter international studies conducted in 2004, 2010, and 2016 in adults who had need of invasive MV for more than 12 h. We collected data on baseline characteristics, variables related to management ventilator settings, and complications while patients were ventilated or until day 28.

RESULTS

Among the 20,929 patients enrolled, we included 12,618 (60%) who started the weaning from MV, of whom 1722 (14%) were patients with acute brain injury. In the acutely brain-injured cohort, 538 patients (31%) did not undergo planned extubation, defined as the need for a tracheostomy without an attempt of extubation, accidental extubation, and death. Among the 1184 planned extubated patients with acute brain injury, 202 required reintubation (17%). Patients with acute brain injury had a higher odds for unplanned extubation (odds ratio [OR] 1.35, confidence interval for 95% [CI 95%] 1.19-1.54; p < 0.001), a higher odds of failure after the first attempt of weaning (spontaneous breathing trial or gradual reduction of ventilatory support; OR 1.14 [CI 95% 1.01-1.30; p = 0.03]), and a higher odds for reintubation (OR 1.41 [CI 95% 1.20-1.66; p < 0.001]) than patients without brain injury. Patients with hemorrhagic stroke had the highest odds for unplanned extubation (OR 1.47 [CI 95% 1.22-1.77; p < 0.001]), of failed extubation after the first attempt of weaning (OR 1.28 [CI 95% 1.06-1.55; p = 0.009]), and for reintubation (OR 1.49 [CI 95% 1.17-1.88; p < 0.001]). In relation to weaning evolution over time in patients with acute brain injury, the risk for unplanned extubation showed a downward trend; the risk for reintubation was not associated to time; and there was a significant increase in the percentage of patients who underwent extubation after the first attempt of weaning from MV.

CONCLUSIONS

Patients with acute brain injury, compared with patients without brain injury, present higher odds of undergoing unplanned extubated after weaning was started, lower odds of being extubated after the first attempt, and a higher risk of reintubation.

Mechanical ventilation in Spain, 1998-2016: Changes in the disconnection of mechanical ventilation

PURPOSE

To evaluate changes in the disconnection of mechanical ventilation in Spain from 1998 to 2016.

DESIGN

Post-hoc analysis of four cohort studies.

AMBIT

138 Spanish ICUs.

PATIENTS

2141 patients scheduled extubated.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Demographics, reason for mechanical ventilation, complications, methods for disconnection, failure on the first attempt at disconnection, duration of weaning, reintubation, post-reintubation tracheotomy, ICU stay and mortality.

RESULTS

There was a significant increase (p < 0.001) in the use of gradual reduction of support pressure. The adjusted probability of using the gradual reduction in pressure support versus a spontaneous breathing trial has increased over time, both for the first attempt at disconnection (taking the 1998 study as a reference: odds ratio 0.99 in 2004, 0.57 in 2010 and 2.43 in 2016) and for difficult/prolonged disconnection (taking the 1998 study as a reference: odds ratio 2.29 in 2004, 1.23 in 2010 and 2.54 in 2016). The proportion of patients extubated after the first attempt at disconnection has increased over time. There is a decrease in the ventilation time dedicated to weaning (from 45% in 1998 to 36% in 2016). However, the duration in difficult/prolonged weaning has not decreased (median 3 days in all studies, p = 0.435).

CONCLUSIONS

There have been significant changes in the mode of disconnection of mechanical ventilation, with a progressive increase in the use of gradual reduction of pressure support. No relevant changes in outcomes have been observed.

Clinical characteristics, physiological features, and outcomes associated with hypercapnia in patients with acute hypoxemic respiratory failure due to COVID-19---insights from the PRoVENT-COVID study

PURPOSE

We determined the incidence of hypercapnia and associations with outcome in invasively ventilated COVID-19 patients.

METHODS

Posthoc analysis of a national, multicenter, observational study in 22 ICUs. Patients were classified as 'hypercapnic' or 'normocapnic' in the first three days of invasive ventilation. Primary endpoint was prevalence of hypercapnia. Secondary endpoints were ventilator parameters, length of stay (LOS) in ICU and hospital, and mortality in ICU, hospital, at day 28 and 90.

RESULTS

Of 824 patients, 485 (58.9%) were hypercapnic. Hypercapnic patients had a higher BMI and had COPD, severe ARDS and venous thromboembolic events more often. Hypercapnic patients were ventilated with lower tidal volumes, higher respiratory rates, higher driving pressures, and with more mechanical power of ventilation. Hypercapnic patients had comparable minute volumes but higher ventilatory ratios than normocapnic patients. In hypercapnic patients, ventilation and LOS in ICU and hospital was longer, but mortality was comparable to normocapnic patients.

CONCLUSION

Hypercapnia occurs often in invasively ventilated COVID-19 patients. Main differences between hypercapnic and normocapnic patients are severity of ARDS, occurrence of venous thromboembolic events, and a higher ventilation ratio. Hypercapnia has an association with duration of ventilation and LOS in ICU and hospital, but not with mortality.

Myocardial Function during Ventilation with Lower versus Higher Positive End-Expiratory Pressure in Patients without ARDS

The aim of this study was to investigate whether lower PEEP (positive end-expiratory pressure) had beneficial effects on myocardial function among intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) compared to higher PEEP. In this pre-planned substudy of a randomized controlled trial (RELAx), comparing lower to higher PEEP, 44 patients underwent transthoracic echocardiography. The exclusion criteria were known poor left ventricular function and severe shock requiring high dosages of norepinephrine. To create contrast, we also excluded patients who received PEEP between 2 cmH2O and 7 cmH2O in the two randomization arms of the study. The primary outcome was the right ventricular myocardial performance index (MPI), a measure of systolic and diastolic function. The secondary outcomes included systolic and diastolic function parameters. A total of 20 patients were ventilated with lower PEEP (mean ± SD, 0 ± 1 cmH2O), and 24 patients, with higher PEEP (8 ± 1 cmH2O) (mean difference, -8 cmH2O; 95% CI: -8.1 to -7.9 cmH2O; p = 0.01). The tidal volume size was low in both groups (median (IQR), 7.2 (6.3 to 8.1) versus 7.0 (5.3 to 9.1) ml/kg PBW; p = 0.97). The median right ventricular MPI was 0.32 (IQR, 0.26 to 0.39) in the lower-PEEP group versus 0.38 (0.32 to 0.41) in the higher-PEEP group; the median difference was -0.03; 95% CI: -0.11 to 0.03; p = 0.33. The other systolic and diastolic parameters were similar. In patients without ARDS ventilated with a low tidal volume, a lower PEEP had no beneficial effects on the right ventricular MPI.

The Effect of Clusters of Double Triggering and Ineffective Efforts in Critically Ill Patients

OBJECTIVES

To characterize clusters of double triggering and ineffective inspiratory efforts throughout mechanical ventilation and investigate their associations with mortality and duration of ICU stay and mechanical ventilation.

DESIGN

Registry-based, real-world study.

BACKGROUND

Asynchronies during invasive mechanical ventilation can occur as isolated events or in clusters and might be related to clinical outcomes.

SUBJECTS

Adults requiring mechanical ventilation greater than 24 hours for whom greater than or equal to 70% of ventilator waveforms were available.

INTERVENTIONS

We identified clusters of double triggering and ineffective inspiratory efforts and determined their power and duration. We used Fine-Gray's competing risk model to analyze their effects on mortality and generalized linear models to analyze their effects on duration of mechanical ventilation and ICU stay.

MEASUREMENTS AND MAIN RESULTS

We analyzed 58,625,796 breaths from 180 patients. All patients had clusters (mean/d, 8.2 [5.4-10.6]; mean power, 54.5 [29.6-111.4]; mean duration, 20.3 min [12.2-34.9 min]). Clusters were less frequent during the first 48 hours (5.5 [2.5-10] vs 7.6 [4.4-9.9] in the remaining period [p = 0.027]). Total number of clusters/d was positively associated with the probability of being discharged alive considering the total period of mechanical ventilation (p = 0.001). Power and duration were similar in the two periods. Power was associated with the probability of being discharged dead (p = 0.03), longer mechanical ventilation (p < 0.001), and longer ICU stay (p = 0.035); cluster duration was associated with longer ICU stay (p = 0.027).

CONCLUSIONS

Clusters of double triggering and ineffective inspiratory efforts are common. Although higher numbers of clusters might indicate better chances of survival, clusters with greater power and duration indicate a risk of worse clinical outcomes.

Metabolomic diferences between COVID-19 and H1N1 influenza induced ARDS

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by lung inflammation and pulmonary edema. Coronavirus disease 2019 (COVID-19) is associated with ARDS in the more severe cases. This study aimed to compare the specificity of the metabolic alterations induced by COVID-19 or Influenza A pneumonia (IAP) in ARDS.

METHODS

Eighteen patients with ARDS due to COVID-19 and twenty patients with ARDS due to IAP, admitted to the intensive care unit. ARDS was defined as in the American-European Consensus Conference. As compared with patients with COVID-19, patients with IAP were younger and received more often noradrenaline to maintain a mean arterial pressure > 65 mm Hg. Serum samples were analyzed by Nuclear Magnetic Resonance Spectroscopy. Multivariate Statistical Analyses were used to identify metabolic differences between groups. Metabolic pathway analysis was performed to identify the most relevant pathways involved in ARDS development.

RESULTS

ARDS due to COVID-19 or to IAP induces a different regulation of amino acids metabolism, lipid metabolism, glycolysis, and anaplerotic metabolism. COVID-19 causes a significant energy supply deficit that induces supplementary energy-generating pathways. In contrast, IAP patients suffer more marked inflammatory and oxidative stress responses. The classificatory model discriminated against the cause of pneumonia with a success rate of 100%.

CONCLUSIONS

Our findings support the concept that ARDS is associated with a characteristic metabolomic profile that may discriminate patients with ARDS of different etiologies, being a potential biomarker for the diagnosis, prognosis, and management of this condition.

Long-term survival of mechanically ventilated patients with severe COVID-19: an observational cohort study

Background

Information is lacking regarding long-term survival and predictive factors for mortality in patients with acute hypoxemic respiratory failure due to coronavirus disease 2019 (COVID-19) and undergoing invasive mechanical ventilation. We aimed to estimate 180-day mortality of patients with COVID-19 requiring invasive ventilation, and to develop a predictive model for long-term mortality.

Methods

Retrospective, multicentre, national cohort study between March 8 and April 30, 2020 in 16 intensive care units (ICU) in Spain. Participants were consecutive adults who received invasive mechanical ventilation for COVID-19. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection detected in positive testing of a nasopharyngeal sample and confirmed by real time reverse-transcriptase polymerase chain reaction (rt-PCR). The primary outcomes was 180-day survival after hospital admission. Secondary outcomes were length of ICU and hospital stay, and ICU and in-hospital mortality. A predictive model was developed to estimate the probability of 180-day mortality.

Results

868 patients were included (median age, 64 years [interquartile range [IQR], 56–71 years]; 72% male). Severity at ICU admission, estimated by SAPS3, was 56 points [IQR 50–63]. Prior to intubation, 26% received some type of noninvasive respiratory support. The unadjusted overall 180-day survival rates was 59% (95% CI 56–62%). The predictive factors measured during ICU stay, and associated with 180-day mortality were: age [Odds Ratio [OR] per 1-year increase 1.051, 95% CI 1.033–1.068)), SAPS3 (OR per 1-point increase 1.027, 95% CI 1.011–1.044), diabetes (OR 1.546, 95% CI 1.085–2.204), neutrophils to lymphocytes ratio (OR per 1-unit increase 1.008, 95% CI 1.001–1.016), failed attempt of noninvasive positive pressure ventilation prior to orotracheal intubation (OR 1.878 (95% CI 1.124–3.140), use of selective digestive decontamination strategy during ICU stay (OR 0.590 (95% CI 0.358–0.972) and administration of low dosage of corticosteroids (methylprednisolone 1 mg/kg) (OR 2.042 (95% CI 1.205–3.460).

Conclusion

The long-term survival of mechanically ventilated patients with severe COVID-19 reaches more than 50% and may help to provide individualized risk stratification and potential treatments.

Trial registration: ClinicalTrials.gov Identifier: NCT04379258. Registered 10 April 2020 (retrospectively registered)

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00929-y.

Driving Pressure Is a Risk Factor for ARDS in Mechanically Ventilated Subjects Without ARDS

BACKGROUND

Driving pressure (ΔP) has been described as a risk factor for mortality in patients with ARDS. However, the role of ΔP in the outcome of patients without ARDS and on mechanical ventilation has received less attention. Our objective was to evaluate the association between ΔP on the first day of mechanical ventilation with the development of ARDS.

METHODS

This was a post hoc analysis of a multicenter, prospective, observational, international study that included subjects who were on mechanical ventilation for > 12 h. Our objective was to evaluate the association between ΔP on the first day of mechanical ventilation with the development of ARDS. To assess the effect of ΔP, a logistic regression analysis was performed when adjusting for other potential risk factors. Validation of the results obtained was performed by using a bootstrap method and by repeating the same analyses at day 2.

RESULTS

A total of 1,575 subjects were included, of whom 65 (4.1%) developed ARDS. The ΔP was independently associated with ARDS (odds ratio [OR] 1.12, 95% CI 1.07-1.18 for each cm H₂O of ΔP increase, P < .001). The same results were observed at day 2 (OR 1.14, 95% CI 1.07-1.21; P < .001) and after bootstrap validation (OR 1.13, 95% CI 1.04-1.22; P < .001). When taking the prevalence of ARDS in the lowest quartile of ΔP (≤9 cm H₂O) as a reference, the subjects with ΔP > 12-15 cm H₂O and those with ΔP > 15 cm H₂O presented a higher probability of ARDS (OR 3.65, 95% CI 1.32-10.04 [P = .01] and OR 7.31, 95% CI, 2.89-18.50 [P < .001], respectively).

CONCLUSIONS

In the subjects without ARDS, a higher level of ΔP on the first day of mechanical ventilation was associated with later development of ARDS. (ClinicalTrials.gov registration NCT02731898.).

Optimal Positive End Expiratory Pressure Levels in Ventilated Patients Without Acute Respiratory Distress Syndrome: A Bayesian Network Meta-Analysis and Systematic Review of Randomized Controlled Trials

Background: To find the optimal positive end expiratory pressure (PEEP) in mechanical ventilated patients without Acute Respiratory Distress Syndrome (ARDS), we conducted a Bayesian network meta-analysis and systematic review of randomized controlled trials (RCTs) comparing different level of PEEP based on a novel classification of PEEP level: ZEEP group (PEEP = 0 cm H2O); lower PEEP group (PEEP = 1–6 cm H2O); intermediate PEEP group (PEEP = 7–10 cm H2O); higher PEEP group (PEEP > 10 cm H2O).

Result: Twenty eight eligible studies with 2,712 patients were included. There were no significant differences in the duration of mechanical ventilation between higher and intermediate PEEP (MD: 0.020, 95% CI: −0.14, 0.28), higher and lower PEEP (MD: −0.010, 95% CI: −0.23, 0.22), higher PEEP and ZEEP (MD: 0.010, 95% CI: −0.40, 0.22), intermediate and lower PEEP (MD: −0.040, 95% CI: −0.18, 0.040), intermediate PEEP and ZEEP (MD: −0.010, 95% CI: −0.42, 0.10), lower PEEP and ZEEP (MD: 0.020, 95% CI: −0.32, 0.13), respectively. Higher PEEP was associated with significantly higher PaO2/FiO2 ratio(PFR) when compared to ZEEP (MD: 73.24, 95% CI: 11.03, 130.7), and higher incidence of pneumothorax when compared to intermediate PEEP, lower PEEP and ZEEP (OR: 2.91e + 12, 95% CI: 40.3, 1.76e + 39; OR: 1.85e + 12, 95% CI: 29.2, 1.18e + 39; and OR: 1.44e + 12, 95% CI: 16.9, 8.70e + 38, respectively). There was no association between PEEP levels and other secondary outcomes.

Conclusion: We identified higher PEEP was associated with significantly higher PFR and higher incidence of pneumothorax. Nonetheless, in terms of other outcomes, no significant differences were detected among four levels of PEEP.

Systematic Review Registration: The study had registered on an international prospective register of systematic reviews, PROSPERO, on 09 April 2021, identifier: [CRD42021241745].

The association of the COVID-19 pandemic and short-term outcomes of non-COVID-19 critically ill patients: an observational cohort study in Brazilian ICUs

PURPOSE

To assess whether intensive care unit (ICU) outcomes for patients not affected by coronavirus disease 2019 (COVID-19) worsened during the COVID-19 pandemic.

METHODS

Retrospective cohort study including prospectively collected information of patients admitted to 165 ICUs in a hospital network in Brazil between 2011 and 2020. Association between admission in 2020 and worse hospital outcomes was performed using different techniques, including assessment of changes in illness severity of admitted patients, a variable life-adjusted display of mortality during 2020, a multivariate mixed regression model with admission year as both fixed effect and random slope adjusted for SAPS 3 score, an analysis of trends in performance using standardized mortality ratio (SMR) and standardized resource use (SRU), and perturbation analysis.

RESULTS

A total of 644,644 admissions were considered. After excluding readmissions and patients with COVID-19, 514,219 patients were available for analysis. Non-COVID-19 patients admitted in 2020 had slightly lower age and SAPS 3 score but a higher mortality (6.4%) when compared with previous years (2019: 5.6%; 2018: 6.1%). Variable-adjusted life display (VLAD) in 2020 increased but started to decrease as the number of COVID-19 cases increased; this trend reversed as number of COVID cases reduced but recurred on the second wave. After logistic regression, being admitted in 2020 was associated with higher mortality when compared to previous years from 2016 and 2019. Individual ICUs standardized mortality ratio also increased during 2020 (higher SMR) while resource use remained constant, suggesting worsening performance. A perturbation analysis further confirmed changes in ICU outcomes for non-COVID-19 patients.

CONCLUSION

Hospital outcomes of non-COVID-19 critically ill patients worsened during the pandemic in 2020, possibly resulting in an increased number of deaths in critically ill non-COVID patients.

Effect of different levels of PEEP on mortality in ICU patients without acute respiratory distress syndrome: systematic review and meta-analysis with trial sequential analysis

OBJECTIVE

To determine whether higher positive end- expiratory pressure (PEEP) could provide a survival advantage for patients without acute respiratory distress syndrome (ARDS) compared with lower PEEP.

METHODS

Eligible studies were identified through searches of Embase, Cochrane Library, Web of Science, Medline, and Wanfang database from inception up to 1 June 2021. Trial sequential analysis (TSA) was used in this meta-analysis.

DATA SYNTHESIS

Twenty-seven randomized controlled trials (RCTs) were identified for further evaluation. Higher and lower PEEP arms included 1330 patients and 1650 patients, respectively. A mean level of 9.6±3.4 cmH₂O was applied in the higher PEEP groups and 1.9±2.6 cmH₂O was used in the lower PEEP groups. Higher PEEP, compared with lower PEEP, was not associated with reduction of all-cause mortality (RR 1.03; 95% CI 0.91-1.18; P =0.627), and 28-day mortality (RR 1.07 ; 95% CI 0.92-1.24; P =0.365). In terms of risk of ARDS (RR 0.43; 95% CI 0.24-0.78; P =0.005), duration of intensive care unit (MD -1.04; 95%CI-1.36 to -0.73; P < 0.00001), and oxygenation (MD 40.30; 95%CI 0.94 to 79.65; P = 0.045), higher PEEP was superior to lower PEEP. Besides, the pooled analysis showed no significant differences between groups both in the duration of mechanical ventilation (MD 0.00; 95%CI-0.13 to 0.13; P = 0.996) and hospital stay (MD -0.66; 95%CI-1.94 to 0.61; P = 0.309). More importantly, lower PEEP did not increase the risk of pneumonia, atelectasis, barotrauma, hypoxemia, or hypotension among patients compared with higher PEEP. The TSA analysis showed that the results of all-cause mortality and 28-day mortality might be false-negative results.

CONCLUSIONS

Our results suggest that a lower PEEP ventilation strategy was non-inferior to a higher PEEP ventilation strategy in ICU patients without ARDS, with no increased risk of all-cause mortality and 28-day mortality. Further high-quality RCTs should be performed to confirm these findings.

Outcome of acute hypoxaemic respiratory failure: insights from the LUNG SAFE Study

BACKGROUND

Current incidence and outcome of patients with acute hypoxaemic respiratory failure requiring mechanical ventilation in the intensive care unit (ICU) are unknown, especially for patients not meeting criteria for acute respiratory distress syndrome (ARDS).

METHODS

An international, multicentre, prospective cohort study of patients presenting with hypoxaemia early in the course of mechanical ventilation, conducted during four consecutive weeks in the winter of 2014 in 459 ICUs from 50 countries (LUNG SAFE). Patients were enrolled with arterial oxygen tension/inspiratory oxygen fraction ratio ≤300 mmHg, new pulmonary infiltrates and need for mechanical ventilation with a positive end-expiratory pressure of ≥5 cmH₂O. ICU prevalence, causes of hypoxaemia, hospital survival and factors associated with hospital mortality were measured. Patients with unilateral versus bilateral opacities were compared.

FINDINGS

12 906 critically ill patients received mechanical ventilation and 34.9% with hypoxaemia and new infiltrates were enrolled, separated into ARDS (69.0%), unilateral infiltrate (22.7%) and congestive heart failure (CHF; 8.2%). The global hospital mortality was 38.6%. CHF patients had a mortality comparable to ARDS (44.1% versus 40.4%). Patients with unilateral-infiltrate had lower unadjusted mortality, but similar adjusted mortality compared to those with ARDS. The number of quadrants on chest imaging was associated with an increased risk of death. There was no difference in mortality comparing patients with unilateral-infiltrate and ARDS with only two quadrants involved.

INTERPRETATION

More than one-third of patients receiving mechanical ventilation have hypoxaemia and new infiltrates with a hospital mortality of 38.6%. Survival is dependent on the degree of pulmonary involvement whether or not ARDS criteria are reached.

Mechanical ventilation in Spain, 1998-2016: changes in the disconnection of mechanical ventilation

PURPOSE

To evaluate changes in the disconnection of mechanical ventilation in Spain from 1998 to 2016.

DESIGN

Post-hoc analysis of four cohort studies.

AMBIT

138 Spanish ICUs.

PATIENTS

2141 patients scheduled extubated.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Demographics, reason for mechanical ventilation, complications, methods for disconnection, failure on the first attempt at disconnection, duration of weaning, reintubation, post-reintubation tracheotomy, ICU stay and mortality.

RESULTS

There was a significant increase (p<0.001) in the use of gradual reduction of support pressure. The adjusted probability of using the gradual reduction in pressure support versus a spontaneous breathing trial has increased over time, both for the first attempt at disconnection (taking the 1998 study as a reference: odds ratio 0.99 in 2004, 0.57 in 2010 and 2.43 in 2016) and for difficult/prolonged disconnection (taking the 1998 study as a reference: odds ratio 2.29 in 2004, 1.23 in 2010 and 2.54 in 2016). The proportion of patients extubated after the first attempt at disconnection has increased over time. There is a decrease in the ventilation time dedicated to weaning (from 45% in 1998 to 36% in 2016). However, the duration in difficult/prolonged weaning has not decreased (median 3 days in all studies, p=0.435).

CONCLUSIONS

There have been significant changes in the mode of disconnection of mechanical ventilation, with a progressive increase in the use of gradual reduction of pressure support. No relevant changes in outcomes have been observed.

Propensity-Adjusted Comparison of Mortality of Elderly Versus Very Elderly Ventilated Patients

BACKGROUND

The growing proportion of elderly intensive care patients constitutes a public health challenge. The benefit of critical care in these patients remains unclear. We compared outcomes in elderly versus very elderly subjects receiving mechanical ventilation.

METHODS

In total, 5,557 mechanically ventilated subjects were included in our post hoc retrospective analysis, a subgroup of the VENTILA study. We divided the cohort into 2 subgroups on the basis of age: very elderly subjects (age ≥ 80 y; n = 1,430), and elderly subjects (age 65-79 y; n = 4,127). A propensity score on being very elderly was calculated. Evaluation of associations with 28-d mortality was done with logistic regression analysis.

RESULTS

Very elderly subjects were clinically sicker as expressed by higher SAPS II scores (53 ± 18 vs 50 ± 18, P < .001), and their rates of plateau pressure < 30 cm H₂O were higher, whereas other parameters did not differ. The 28-d mortality was higher in very elderly subjects (42% vs 34%, P < .001) and remained unchanged after propensity score adjustment (adjusted odds ratio 1.31 [95% CI 1.16-1.49], P < .001).

CONCLUSIONS

Age was an independent and unchangeable risk factor for death in mechanically ventilated subjects. However, survival rates of very elderly subjects were > 50%. Denial of critical care based solely on age is not justified. (ClinicalTrials.gov registration NCT02731898.).

Evolution Over Time of Ventilatory Management and Outcome of Patients With Neurologic Disease

OBJECTIVES

To describe the changes in ventilator management over time in patients with neurologic disease at ICU admission and to estimate factors associated with 28-day hospital mortality.

DESIGN

Secondary analysis of three prospective, observational, multicenter studies.

SETTING

Cohort studies conducted in 2004, 2010, and 2016.

PATIENTS

Adult patients who received mechanical ventilation for more than 12 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among the 20,929 patients enrolled, we included 4,152 (20%) mechanically ventilated patients due to different neurologic diseases. Hemorrhagic stroke and brain trauma were the most common pathologies associated with the need for mechanical ventilation. Although volume-cycled ventilation remained the preferred ventilation mode, there was a significant (p < 0.001) increment in the use of pressure support ventilation. The proportion of patients receiving a protective lung ventilation strategy was increased over time: 47% in 2004, 63% in 2010, and 65% in 2016 (p < 0.001), as well as the duration of protective ventilation strategies: 406 days per 1,000 mechanical ventilation days in 2004, 523 days per 1,000 mechanical ventilation days in 2010, and 585 days per 1,000 mechanical ventilation days in 2016 (p < 0.001). There were no differences in the length of stay in the ICU, mortality in the ICU, and mortality in hospital from 2004 to 2016. Independent risk factors for 28-day mortality were age greater than 75 years, Simplified Acute Physiology Score II greater than 50, the occurrence of organ dysfunction within first 48 hours after brain injury, and specific neurologic diseases such as hemorrhagic stroke, ischemic stroke, and brain trauma.

CONCLUSIONS

More lung-protective ventilatory strategies have been implemented over years in neurologic patients with no effect on pulmonary complications or on survival. We found several prognostic factors on mortality such as advanced age, the severity of the disease, organ dysfunctions, and the etiology of neurologic disease.

Impact of positive biphasic pressure during low and high inspiratory efforts in Pseudomonas aeruginosa-induced pneumonia

BACKGROUND

During pneumonia, normal alveolar areas coexist adjacently with consolidated areas, and high inspiratory efforts may predispose to lung damage. To date, no study has evaluated different degrees of effort during Biphasic positive airway pressure (BIVENT) on lung and diaphragm damage in experimental pneumonia, though largely used in clinical setting. We aimed to evaluate lung damage, genes associated with ventilator-induced lung injury (VILI) and diaphragmatic injury, and blood bacteria in pressure-support ventilation (PSV), BIVENT with low and high inspiratory efforts in experimental pneumonia.

MATERIAL AND METHODS

Twenty-eight male Wistar rats (mean ± SD weight, 333±78g) were submitted Pseudomonas aeruginosa-induced pneumonia. After 24-h, animals were ventilated for 1h in: 1) PSV; 2) BIVENT with low (BIVENTLow-Effort); and 3) BIVENT with high inspiratory effort (BIVENTHigh-Effort). BIVENT was set at Phigh to achieve VT = 6 ml/kg and Plow at 5 cmH2O (n = 7/group). High- and low-effort conditions were obtained through anaesthetic infusion modulation based on neuromuscular drive (P0.1). Lung mechanics, histological damage score, blood bacteria, and expression of genes related to VILI in lung tissue, and inflammation in diaphragm tissue.

RESULTS

Transpulmonary peak pressure and histological damage score were higher in BIVENTHigh-Effort compared to BIVENTLow-Effort and PSV [16.1 ± 1.9cmH2O vs 12.8 ± 1.5cmH2O and 12.5 ± 1.6cmH2O, p = 0.015, and p = 0.010; median (interquartile range) 11 (9-13) vs 7 (6-9) and 7 (6-9), p = 0.021, and p = 0.029, respectively]. BIVENTHigh-Effort increased interleukin-6 expression compared to BIVENTLow-Effort (p = 0.035) as well as expressions of cytokine-induced neutrophil chemoattractant-1, amphiregulin, and type III procollagen compared to PSV (p = 0.001, p = 0.001, p = 0.004, respectively). Tumour necrosis factor-α expression in diaphragm tissue and blood bacteria were higher in BIVENTHigh-Effort than BIVENTLow-Effort (p = 0.002, p = 0.009, respectively).

CONCLUSION

BIVENT requires careful control of inspiratory effort to avoid lung and diaphragm damage, as well as blood bacteria. P0.1 might be considered a helpful parameter to optimize inspiratory effort.

Is COPD associated with increased risk for microaspiration in intubated critically ill patients?

Background

Although COPD patients are at higher risk for aspiration when breathing spontaneously, no information is available on the risk for microaspiration in invasively ventilated COPD patients. The aim of our study was to determine the relationship between COPD and abundant microaspiration in intubated critically ill patients.

Methods

This was a retrospective analysis of prospectively collected data, provided by 3 randomized controlled trials on microaspiration in critically ill patients receiving invasive mechanical ventilation for more than 48 h. Abundant microaspiration was defined as the presence of pepsin and or alpha-amylase at significant levels in tracheal aspirates. In all study patients, pepsin and alpha-amylase were quantitatively measured in all tracheal aspirates collected during a 48-h period. COPD was defined using spirometry criteria.

Results

Among the 515 included patients, 70 (14%) had proven COPD. Pepsin and alpha-amylase were quantitatively measured in 3873 and 3764 tracheal aspirates, respectively. No significant difference was found in abundant microaspiration rate between COPD and non-COPD patients (62 of 70 patients (89%) vs 366 of 445 (82%) patients, p = 0.25). Similarly, no significant difference was found in abundant microaspiration of gastric contents (53% vs 45%, p = 0.28), oropharyngeal secretions (71% vs 71%, p = 0.99), or VAP (19% vs 22%, p = 0.65) rates between the two groups. No significant difference was found between COPD and non-COPD patients in duration of mechanical ventilation, ICU length of stay, or ICU mortality.

Conclusions

Our results suggest that COPD is not associated with increased risk for abundant microaspiration in intubated critically ill patients.

Effect of a Lower vs Higher Positive End-Expiratory Pressure Strategy on Ventilator-Free Days in ICU Patients Without ARDS: A Randomized Clinical Trial

IMPORTANCE

It is uncertain whether invasive ventilation can use lower positive end-expiratory pressure (PEEP) in critically ill patients without acute respiratory distress syndrome (ARDS).

OBJECTIVE

To determine whether a lower PEEP strategy is noninferior to a higher PEEP strategy regarding duration of mechanical ventilation at 28 days.

DESIGN, SETTING, AND PARTICIPANTS

Noninferiority randomized clinical trial conducted from October 26, 2017, through December 17, 2019, in 8 intensive care units (ICUs) in the Netherlands among 980 patients without ARDS expected not to be extubated within 24 hours after start of ventilation. Final follow-up was conducted in March 2020.

INTERVENTIONS

Participants were randomized to receive invasive ventilation using either lower PEEP, consisting of the lowest PEEP level between 0 and 5 cm H2O (n = 476), or higher PEEP, consisting of a PEEP level of 8 cm H2O (n = 493).

MAIN OUTCOMES AND MEASURES

The primary outcome was the number of ventilator-free days at day 28, with a noninferiority margin for the difference in ventilator-free days at day 28 of -10%. Secondary outcomes included ICU and hospital lengths of stay; ICU, hospital, and 28- and 90-day mortality; development of ARDS, pneumonia, pneumothorax, severe atelectasis, severe hypoxemia, or need for rescue therapies for hypoxemia; and days with use of vasopressors or sedation.

RESULTS

Among 980 patients who were randomized, 969 (99%) completed the trial (median age, 66 [interquartile range {IQR}, 56-74] years; 246 [36%] women). At day 28, 476 patients in the lower PEEP group had a median of 18 ventilator-free days (IQR, 0-27 days) and 493 patients in the higher PEEP group had a median of 17 ventilator-free days (IQR, 0-27 days) (mean ratio, 1.04; 95% CI, 0.95-∞; P = .007 for noninferiority), and the lower boundary of the 95% CI was within the noninferiority margin. Occurrence of severe hypoxemia was 20.6% vs 17.6% (risk ratio, 1.17; 95% CI, 0.90-1.51; P = .99) and need for rescue strategy was 19.7% vs 14.6% (risk ratio, 1.35; 95% CI, 1.02-1.79; adjusted P = .54) in patients in the lower and higher PEEP groups, respectively. Mortality at 28 days was 38.4% vs 42.0% (hazard ratio, 0.89; 95% CI, 0.73-1.09; P = .99) in patients in the lower and higher PEEP groups, respectively. There were no statistically significant differences in other secondary outcomes.

CONCLUSIONS AND RELEVANCE

Among patients in the ICU without ARDS who were expected not to be extubated within 24 hours, a lower PEEP strategy was noninferior to a higher PEEP strategy with regard to the number of ventilator-free days at day 28. These findings support the use of lower PEEP in patients without ARDS.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03167580.

How to ventilate obstructive and asthmatic patients

Exacerbations are part of the natural history of chronic obstructive pulmonary disease and asthma. Severe exacerbations can cause acute respiratory failure, which may ultimately require mechanical ventilation. This review summarizes practical ventilator strategies for the management of patients with obstructive airway disease. Such strategies include non-invasive mechanical ventilation to prevent intubation, invasive mechanical ventilation, from the time of intubation to weaning, and strategies intended to prevent post-extubation acute respiratory failure. The role of tracheostomy, the long-term prognosis, and potential future adjunctive strategies are also discussed. Finally, the physiological background that underlies these strategies is detailed.

Invasive Mechanical Ventilation in Chronic Obstructive Pulmonary Disease Exacerbations

Chronic obstructive pulmonary disease (COPD) continues to be an important cause of morbidity, mortality, and health care costs worldwide. Although there exist some heterogeneity between patients, the course of COPD is characterized by recurrent acute exacerbations, which are among the most common causes of medical admission to hospital. Patients with frequent exacerbations have accelerated lung function decline, worse quality of life, and greater mortality. Therefore, interest is growing in assessing the effectiveness of interventions used to treat exacerbations. The present review summarizes the current evidence regarding the use of ventilatory management to treat COPD and the implementation of novel cost-effective strategies, such as high-flow oxygenation or extracorporeal carbon dioxide removal to improve clinical outcomes and functional recovery in this disease and to reduce the associated costs.

Mechanical ventilation in Spain, 1998-2016: Epidemiology and outcomes

PURPOSE

To evaluate changes in the epidemiology of mechanical ventilation in Spain from 1998 to 2016.

DESIGN

A post hoc analysis of four cohort studies was carried out.

SETTING

A total of 138 Spanish ICUs.

PATIENTS

A sample of 4293 patients requiring invasive mechanical ventilation for more than 12h or noninvasive ventilation for more than 1h.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Demographic variables, reason for mechanical ventilation, variables related to ventilatory support (ventilation mode, tidal volume, PEEP, airway pressures), complications during mechanical ventilation, duration of mechanical ventilation, ICU stay and ICU mortality.

RESULTS

There was an increase in severity (SAPSII: 43 points in 1998 vs. 47 points in 2016), changes in the reason for mechanical ventilation (decrease in chronic obstructive pulmonary disease and acute respiratory failure secondary to trauma, and increase in neurological disease and post-cardiac arrest). There was an increase in noninvasive mechanical ventilation as the first mode of ventilatory support (p<0.001). Volume control ventilation was the most commonly used mode, with increased support pressure and pressure-regulated volume-controlled ventilation. A decrease in tidal volume was observed (9ml/kg actual b.w. in 1998 and 6.6ml/kg in 2016; p<0.001) as well as an increase in PEEP (3cmH₂O in 1998 and 6cmH₂O in 2016; p<0.001). In-ICU mortality decreased (34% in 1998 and 27% in 2016; p<0.001), without geographical variability (median OR 1.43; p=0.258).

CONCLUSIONS

A significant decrease in mortality was observed in patients ventilated in Spanish ICUs. These changes in mortality could be related to modifications in ventilation strategy to minimize ventilator-induced lung injury.