Different ventilation intensities among various categories of patients ventilated for reasons other than ARDS--A pooled analysis of 4 observational studies

PURPOSE

We investigated driving pressure (ΔP) and mechanical power (MP) and associations with clinical outcomes in critically ill patients ventilated for reasons other than ARDS.

MATERIALS AND METHODS

Individual patient data analysis of a pooled database that included patients from four observational studies of ventilation. ΔP and MP were compared among invasively ventilated non-ARDS patients with sepsis, with pneumonia, and not having sepsis or pneumonia. The primary endpoint was ΔP; secondary endpoints included MP, ICU mortality and length of stay, and duration of ventilation.

RESULTS

This analysis included 372 (11%) sepsis patients, 944 (28%) pneumonia patients, and 2040 (61%) patients ventilated for any other reason. On day 1, median ΔP was higher in sepsis (14 [11-18] cmH2O) and pneumonia patients (14 [11-18]cmH2O), as compared to patients not having sepsis or pneumonia (13 [10-16] cmH2O) (P < 0.001). Median MP was also higher in sepsis and pneumonia patients. ΔP, as opposed to MP, was associated with ICU mortality in sepsis and pneumonia patients.

CONCLUSIONS

The intensity of ventilation differed between patients with sepsis or pneumonia and patients receiving ventilation for any other reason; ΔP was associated with higher mortality in sepsis and pneumonia patients.

REGISTRATION

This post hoc analysis was not registered; the individual studies that were merged into the used database were registered at clinicaltrials.gov: NCT01268410 (ERICC), NCT02010073 (LUNG SAFE), NCT01868321 (PRoVENT), and NCT03188770 (PRoVENT-iMiC).

Safety and Feasibility of Intraoperative High PEEP Titrated to the Lowest Driving Pressure (ΔP)-Interim Analysis of DESIGNATION

Uncertainty remains about the best level of intraoperative positive end-expiratory pressure (PEEP). An ongoing RCT ('DESIGNATION') compares an 'individualized high PEEP' strategy ('iPEEP')-titrated to the lowest driving pressure (ΔP) with recruitment maneuvers (RM), with a 'standard low PEEP' strategy ('low PEEP')-using 5 cm H2O without RMs with respect to the incidence of postoperative pulmonary complications. This report is an interim analysis of safety and feasibility. From September 2018 to July 2022, we enrolled 743 patients. Data of 698 patients were available for this analysis. Hypotension occurred more often in 'iPEEP' vs. 'low PEEP' (54.7 vs. 44.1%; RR, 1.24 (95% CI 1.07 to 1.44); p < 0.01). Investigators were compliant with the study protocol 285/344 patients (82.8%) in 'iPEEP', and 345/354 patients (97.5%) in 'low PEEP' (p < 0.01). Most frequent protocol violation was missing the final RM at the end of anesthesia before extubation; PEEP titration was performed in 99.4 vs. 0%; PEEP was set correctly in 89.8 vs. 98.9%. Compared to 'low PEEP', the 'iPEEP' group was ventilated with higher PEEP (10.0 (8.0-12.0) vs. 5.0 (5.0-5.0) cm H2O; p < 0.01). Thus, in patients undergoing general anesthesia for open abdominal surgery, an individualized high PEEP ventilation strategy is associated with hypotension. The protocol is feasible and results in clear contrast in PEEP. DESIGNATION is expected to finish in late 2023.

Epidemiology, Ventilation Management and Outcomes of COPD Patients Receiving Invasive Ventilation for COVID-19-Insights from PRoVENT-COVID

Chronic obstructive pulmonary disease (COPD) is a risk factor for death in patients admitted to intensive care units (ICUs) for respiratory support. Previous reports suggested higher mortality in COPD patients with COVID-19. It is yet unknown whether patients with COPD were treated differently compared to non-COPD patients. We compared the ventilation management and outcomes of invasive ventilation for COVID-19 in COPD patients versus non-COPD patients. This was a post hoc analysis of a nation-wide, observational study in the Netherlands. COPD patients were compared to non-COPD patients with respect to key ventilation parameters. The secondary endpoints included adjunctive treatments for refractory hypoxemia, and 28-day mortality. Of a total of 1090 patients, 88 (8.1%) were classified as having COPD. The ventilation parameters were not different between COPD patients and non-COPD patients, except for FiO2, which was higher in COPD patients. Prone positioning was applied more often in COPD patients. COPD patients had higher 28-day mortality than non-COPD patients. COPD had an independent association with 28-day mortality. In this cohort of patients who received invasive ventilation for COVID-19, only FiO2 settings and the use of prone positioning were different between COPD patients and non-COPD patients. COPD patients had higher mortality than non-COPD patients.

Closed-Loop ventilation using sidestream versus mainstream capnography for automated adjustments of minute ventilation-A randomized clinical trial in cardiac surgery patients

BACKGROUND

INTELLiVENT-Adaptive Support Ventilation (ASV) is a closed-loop ventilation mode that uses capnography to adjust tidal volume (VT) and respiratory rate according to a user-set end-tidal CO2 (etCO2) target range. We compared sidestream versus mainstream capnography with this ventilation mode with respect to the quality of breathing in patients after cardiac surgery.

METHODS

Single-center, single-blinded, non-inferiority, randomized clinical trial in adult patients scheduled for elective cardiac surgery that were expected to receive at least two hours of postoperative ventilation in the ICU. Patients were randomized 1:1 to closed-loop ventilation with sidestream or mainstream capnography. Each breath was classified into a zone based on the measured VT, maximum airway pressure, etCO2 and pulse oximetry. The primary outcome was the proportion of breaths spent in a predefined 'optimal' zone of ventilation during the first three hours of postoperative ventilation, with a non-inferiority margin for the difference in the proportions set at -20%. Secondary endpoints included the proportion of breaths in predefined 'acceptable' and 'critical' zones of ventilation, and the proportion of breaths with hypoxemia.

RESULTS

Of 80 randomized subjects, 78 were included in the intention-to-treat analysis. We could not confirm the non-inferiority of closed-loop ventilation using sidestream with respect to the proportion of breaths in the 'optimal' zone (mean ratio 0.87 [0.77 to ∞]; P = 0.116 for non-inferiority). The proportion of breaths with hypoxemia was higher in the sidestream capnography group versus the mainstream capnography group.

CONCLUSIONS

We could not confirm that INTELLiVENT-ASV using sidestream capnography is non-inferior to INTELLiVENT-ASV using mainstream capnography with respect to the quality of breathing in subjects receiving postoperative ventilation after cardiac surgery.

TRIAL REGISTRATION

NCT04599491 (clinicaltrials.gov).

A closed-loop ventilation mode that targets the lowest work and force of breathing reduces the transpulmonary driving pressure in patients with moderate-to-severe ARDS

INTRODUCTION

The driving pressure (ΔP) has an independent association with outcome in patients with acute respiratory distress syndrome (ARDS). INTELLiVENT-Adaptive Support Ventilation (ASV) is a closed-loop mode of ventilation that targets the lowest work and force of breathing.

AIM

To compare transpulmonary and respiratory system ΔP between closed-loop ventilation and conventional pressure controlled ventilation in patients with moderate-to-severe ARDS.

METHODS

Single-center randomized cross-over clinical trial in patients in the early phase of ARDS. Patients were randomly assigned to start with a 4-h period of closed-loop ventilation or conventional ventilation, after which the alternate ventilation mode was selected. The primary outcome was the transpulmonary ΔP; secondary outcomes included respiratory system ΔP, and other key parameters of ventilation.

RESULTS

Thirteen patients were included, and all had fully analyzable data sets. Compared to conventional ventilation, with closed-loop ventilation the median transpulmonary ΔP with was lower (7.0 [5.0-10.0] vs. 10.0 [8.0-11.0] cmH₂O, mean difference - 2.5 [95% CI - 2.6 to - 2.1] cmH₂O; P = 0.0001). Inspiratory transpulmonary pressure and the respiratory rate were also lower. Tidal volume, however, was higher with closed-loop ventilation, but stayed below generally accepted safety cutoffs in the majority of patients.

CONCLUSIONS

In this small physiological study, when compared to conventional pressure controlled ventilation INTELLiVENT-ASV reduced the transpulmonary ΔP in patients in the early phase of moderate-to-severe ARDS. This closed-loop ventilation mode also led to a lower inspiratory transpulmonary pressure and a lower respiratory rate, thereby reducing the intensity of ventilation. Trial registration Clinicaltrials.gov, NCT03211494, July 7, 2017. https://clinicaltrials.gov/ct2/show/NCT03211494?term=airdrop&draw=2&rank=1 .

Broadening the Berlin definition of ARDS to patients receiving high-flow nasal oxygen: an observational study in patients with acute hypoxemic respiratory failure due to COVID-19

BACKGROUND

High-flow nasal oxygen (HFNO) is increasingly used in patients with acute hypoxemic respiratory failure. It is uncertain whether a broadened Berlin definition of acute respiratory distress syndrome (ARDS), in which ARDS can be diagnosed in patients who are not receiving ventilation, results in similar groups of patients receiving HFNO as in patients receiving ventilation.

METHODS

We applied a broadened definition of ARDS in a multicenter, observational study in adult critically ill patients with acute hypoxemic respiratory failure due to coronavirus disease 2019 (COVID-19), wherein the requirement for a minimal level of 5 cm H₂O PEEP with ventilation is replaced by a minimal level of airflow rate with HFNO, and compared baseline characteristics and outcomes between patients receiving HFNO and patients receiving ventilation. The primary endpoint was ICU mortality. We also compared outcomes in risk for death groups using the PaO₂/FiO₂ cutoffs as used successfully in the original definition of ARDS. Secondary endpoints were hospital mortality; mortality on days 28 and 90; need for ventilation within 7 days in patients that started with HFNO; the number of days free from HFNO or ventilation; and ICU and hospital length of stay.

RESULTS

Of 728 included patients, 229 patients started with HFNO and 499 patients with ventilation. All patients fulfilled the broadened Berlin definition of ARDS. Patients receiving HFNO had lower disease severity scores and lower PaO₂/FiO₂ than patients receiving ventilation. ICU mortality was lower in receiving HFNO (22.7 vs 35.6%; p = 0.001). Using PaO₂/FiO₂ cutoffs for mild, moderate and severe arterial hypoxemia created groups with an ICU mortality of 16.7%, 22.0%, and 23.5% (p = 0.906) versus 19.1%, 37.9% and 41.4% (p = 0.002), in patients receiving HFNO versus patients receiving ventilation, respectively.

CONCLUSIONS

Using a broadened definition of ARDS may facilitate an earlier diagnosis of ARDS in patients receiving HFNO; however, ARDS patients receiving HFNO and ARDS patients receiving ventilation have distinct baseline characteristics and mortality rates.

TRIAL REGISTRATION

The study is registered at ClinicalTrials.gov (identifier NCT04719182).

Differences in Ventilation Management and Outcomes between the Two First Waves of the COVID-19 Pandemic-A Comparison between Two Nationwide Observational Studies in The Netherlands

The aim of this analysis was to compare ventilation management and outcomes in invasively ventilated patients with acute hypoxemic respiratory failure due to coronavirus disease 2019 (COVID-19) between the first and second wave in the Netherlands. This is a post hoc analysis of two nationwide observational COVID-19 studies conducted in quick succession. The primary endpoint was ventilation management. Secondary endpoints were tracheostomy use, duration of ventilation, intensive care unit (ICU) and hospital length of stay (LOS), and mortality. We used propensity score matching to control for observed confounding factors. This analysis included 1122 patients from the first and 568 patients from the second wave. Patients in the second wave were sicker, had more comorbidities, and had worse oxygenation parameters. They were ventilated with lower positive end-expiratory pressure and higher fraction inspired oxygen, had a lower oxygen saturation, received neuromuscular blockade more often, and were less often tracheostomized. Duration of ventilation was shorter, but mortality rates were similar. After matching, the fraction of inspired oxygen was lower in the second wave. In patients with acute hypoxemic respiratory failure due to COVID-19, aspects of respiratory care and outcomes rapidly changed over the successive waves.

Optimal Dosing and Timing of High-Dose Corticosteroid Therapy in Hospitalized Patients With COVID-19: Study Protocol for a Retrospective Observational Multicenter Study (SELECT)

BACKGROUND

In hospitalized patients with COVID-19, the dosing and timing of corticosteroids vary widely. Low-dose dexamethasone therapy reduces mortality in patients requiring respiratory support, but it remains unclear how to treat patients when this therapy fails. In critically ill patients, high-dose corticosteroids are often administered as salvage late in the disease course, whereas earlier administration may be more beneficial in preventing disease progression. Previous research has revealed that increased levels of various biomarkers are associated with mortality, and whole blood transcriptome sequencing has the ability to identify host factors predisposing to critical illness in patients with COVID-19.

OBJECTIVE

Our goal is to determine the most optimal dosing and timing of corticosteroid therapy and to provide a basis for personalized corticosteroid treatment regimens to reduce morbidity and mortality in hospitalized patients with COVID-19.

METHODS

This is a retrospective, observational, multicenter study that includes adult patients who were hospitalized due to COVID-19 in the Netherlands. We will use the differences in therapeutic strategies between hospitals (per protocol high-dose corticosteroids or not) over time to determine whether high-dose corticosteroids have an effect on the following outcome measures: mechanical ventilation or high-flow nasal cannula therapy, in-hospital mortality, and 28-day survival. We will also explore biomarker profiles in serum and bronchoalveolar lavage fluid and use whole blood transcriptome analysis to determine factors that influence the relationship between high-dose corticosteroids and outcome. Existing databases that contain routinely collected electronic data during ward and intensive care admissions, as well as existing biobanks, will be used. We will apply longitudinal modeling appropriate for each data structure to answer the research questions at hand.

RESULTS

As of April 2023, data have been collected for a total of 1500 patients, with data collection anticipated to be completed by December 2023. We expect the first results to be available in early 2024.

CONCLUSIONS

This study protocol presents a strategy to investigate the effect of high-dose corticosteroids throughout the entire clinical course of hospitalized patients with COVID-19, from hospital admission to the ward or intensive care unit until hospital discharge. Moreover, our exploration of biomarker and gene expression profiles for targeted corticosteroid therapy represents a first step towards personalized COVID-19 corticosteroid treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05403359; https://clinicaltrials.gov/ct2/show/NCT05403359.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/48183.

Hyperoxia-Induced Lung Injury in Acute Respiratory Distress Syndrome: What is its Relative Impact?

Over the past decade, the interest in oxygen toxicity has led to various observational studies and randomized clinical trials in critically ill patients, assessing association with outcomes and the potential benefit of restrictive oxygenation targets. Yet to date, no consensus has been reached regarding the clinical impact of hyperoxia and hyperoxemia. In this perspective article, we explore the experimental and clinical evidence on hyperoxia-induced lung injury (HILI) and assess its relative impact in current critical care practice, specifically in patients who require oxygen therapy due to acute respiratory distress syndrome (ARDS). Here, we suggest that in current clinical practice in the setting of ARDS HILI may actually be of less importance than other ventilator-related factors.

Oxygen Consumption with High-Flow Nasal Oxygen versus Mechanical Ventilation- An International Multicenter Observational Study in COVID-19 Patients (PROXY-COVID)

The COVID-19 pandemic led to local oxygen shortages worldwide. To gain a better understanding of oxygen consumption with different respiratory supportive therapies, we conducted an international multicenter observational study to determine the precise amount of oxygen consumption with high-flow nasal oxygen (HFNO) and with mechanical ventilation. A retrospective observational study was conducted in three intensive care units (ICUs) in the Netherlands and Spain. Patients were classified as HFNO patients or ventilated patients, according to the mode of oxygen supplementation with which a patient started. The primary endpoint was actual oxygen consumption; secondary endpoints were hourly and total oxygen consumption during the first two full calendar days. Of 275 patients, 147 started with HFNO and 128 with mechanical ventilation. Actual oxygen use was 4.9-fold higher in patients who started with HFNO than in patients who started with ventilation (median 14.2 [8.4-18.4] versus 2.9 [1.8-4.1] L/minute; mean difference = 11.3 [95% CI 11.0-11.6] L/minute; P < 0.01). Hourly and total oxygen consumption were 4.8-fold (P < 0.01) and 4.8-fold (P < 0.01) higher. Actual oxygen consumption, hourly oxygen consumption, and total oxygen consumption are substantially higher in patients that start with HFNO compared with patients that start with mechanical ventilation. This information may help hospitals and ICUs predicting oxygen needs during high-demand periods and could guide decisions regarding the source of distribution of medical oxygen.

Incidence of Air Leaks in Critically Ill Patients with Acute Hypoxemic Respiratory Failure Due to COVID-19

Subcutaneous emphysema, pneumothorax and pneumomediastinum are well-known complications of invasive ventilation in patients with acute hypoxemic respiratory failure. We determined the incidences of air leaks that were visible on available chest images in a cohort of critically ill patients with acute hypoxemic respiratory failure due to coronavirus disease of 2019 (COVID-19) in a single-center cohort in the Netherlands. A total of 712 chest images from 154 patients were re-evaluated by a multidisciplinary team of independent assessors; there was a median of three (2-5) chest radiographs and a median of one (1-2) chest CT scans per patient. The incidences of subcutaneous emphysema, pneumothoraxes and pneumomediastinum present in 13 patients (8.4%) were 4.5%, 4.5%, and 3.9%. The median first day of the presence of an air leak was 18 (2-21) days after arrival in the ICU and 18 (9-22)days after the start of invasive ventilation. We conclude that the incidence of air leaks was high in this cohort of COVID-19 patients, but it was fairly comparable with what was previously reported in patients with acute hypoxemic respiratory failure in the pre-COVID-19 era.

Practice of Awake Prone Positioning in Critically Ill COVID-19 Patients-Insights from the PRoAcT-COVID Study

We describe the incidence, practice and associations with outcomes of awake prone positioning in patients with acute hypoxemic respiratory failure due to coronavirus disease 2019 (COVID-19) in a national multicenter observational cohort study performed in 16 intensive care units in the Netherlands (PRoAcT−COVID-study). Patients were categorized in two groups, based on received treatment of awake prone positioning. The primary endpoint was practice of prone positioning. Secondary endpoint was ‘treatment failure’, a composite of intubation for invasive ventilation and death before day 28. We used propensity matching to control for observed confounding factors. In 546 patients, awake prone positioning was used in 88 (16.1%) patients. Prone positioning started within median 1 (0 to 2) days after ICU admission, sessions summed up to median 12.0 (8.4−14.5) hours for median 1.0 day. In the unmatched analysis (HR, 1.80 (1.41−2.31); p < 0.001), but not in the matched analysis (HR, 1.17 (0.87−1.59); p = 0.30), treatment failure occurred more often in patients that received prone positioning. The findings of this study are that awake prone positioning was used in one in six COVID-19 patients. Prone positioning started early, and sessions lasted long but were often discontinued because of need for intubation.

Association of Time-Varying Intensity of Ventilation With Mortality in Patients With COVID-19 ARDS: Secondary Analysis of the PRoVENT-COVID Study

Background: High intensity of ventilation has an association with mortality in patients with acute respiratory failure. It is uncertain whether similar associations exist in patients with acute respiratory distress syndrome (ARDS) patients due to coronavirus disease 2019 (COVID-19). We investigated the association of exposure to different levels of driving pressure (ΔP) and mechanical power (MP) with mortality in these patients. Methods: PRoVENT-COVID is a national, retrospective observational study, performed at 22 ICUs in the Netherlands, including COVID-19 patients under invasive ventilation for ARDS. Dynamic ΔP and MP were calculated at fixed time points during the first 4 calendar days of ventilation. The primary endpoint was 28-day mortality. To assess the effects of time-varying exposure, Bayesian joint models adjusted for confounders were used. Results: Of 1,122 patients included in the PRoVENT-COVID study, 734 were eligible for this analysis. In the first 28 days, 29.2% of patients died. A significant increase in the hazard of death was found to be associated with each increment in ΔP (HR 1.04, 95% CrI 1.01-1.07) and in MP (HR 1.12, 95% CrI 1.01-1.36). In sensitivity analyses, cumulative exposure to higher levels of ΔP or MP resulted in increased risks for 28-day mortality. Conclusion: Cumulative exposure to higher intensities of ventilation in COVID-19 patients with ARDS have an association with increased risk of 28-day mortality. Limiting exposure to high ΔP or MP has the potential to improve survival in these patients. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT04346342.

Incidence and Practice of Early Prone Positioning in Invasively Ventilated COVID-19 Patients-Insights from the PRoVENT-COVID Observational Study

We describe the incidence and practice of prone positioning and determined the association of use of prone positioning with outcomes in invasively ventilated patients with acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19) in a national, multicenter observational study, performed at 22 intensive care units in the Netherlands. Patients were categorized into 4 groups, based on indication for and actual use of prone positioning. The primary outcome was 28-day mortality. Secondary endpoints were 90-day mortality, and ICU and hospital length of stay. In 734 patients, prone positioning was indicated in 60%-the incidence of prone positioning was higher in patients with an indication than in patients without an indication for prone positioning (77 vs. 48%, p = 0.001). Patients were left in the prone position for median 15.0 (10.5-21.0) hours per full calendar day-the duration was longer in patients with an indication than in patients without an indication for prone positioning (16.0 (11.0-23.0) vs. 14.0 (10.0-19.0) hours, p < 0.001). Ventilator settings and ventilation parameters were not different between the four groups, except for FiO₂ which was higher in patients having an indication for and actually receiving prone positioning. Our data showed no difference in mortality at day 28 between the 4 groups (HR no indication, no prone vs. no indication, prone vs. indication, no prone vs. indication, prone: 1.05 (0.76-1.45) vs. 0.88 (0.62-1.26) vs. 1.15 (0.80-1.54) vs. 0.96 (0.73-1.26) (p = 0.08)). Factors associated with the use of prone positioning were ARDS severity and FiO₂. The findings of this study are that prone positioning is often used in COVID-19 patients, even in patients that have no indication for this intervention. Sessions of prone positioning lasted long. Use of prone positioning may affect outcomes.

Effect of On-Demand vs Routine Nebulization of Acetylcysteine With Salbutamol on Ventilator-Free Days in Intensive Care Unit Patients Receiving Invasive Ventilation: A Randomized Clinical Trial

IMPORTANCE

It remains uncertain whether nebulization of mucolytics with bronchodilators should be applied for clinical indication or preventively in intensive care unit (ICU) patients receiving invasive ventilation.

OBJECTIVE

To determine if a strategy that uses nebulization for clinical indication (on-demand) is noninferior to one that uses preventive (routine) nebulization.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial enrolling adult patients expected to need invasive ventilation for more than 24 hours at 7 ICUs in the Netherlands.

INTERVENTIONS

On-demand nebulization of acetylcysteine or salbutamol (based on strict clinical indications, n = 471) or routine nebulization of acetylcysteine with salbutamol (every 6 hours until end of invasive ventilation, n = 473).

MAIN OUTCOMES AND MEASURES

The primary outcome was the number of ventilator-free days at day 28, with a noninferiority margin for a difference between groups of -0.5 days. Secondary outcomes included length of stay, mortality rates, occurrence of pulmonary complications, and adverse events.

RESULTS

Nine hundred twenty-two patients (34% women; median age, 66 (interquartile range [IQR], 54-75 years) were enrolled and completed follow-up. At 28 days, patients in the on-demand group had a median 21 (IQR, 0-26) ventilator-free days, and patients in the routine group had a median 20 (IQR, 0-26) ventilator-free days (1-sided 95% CI, -0.00003 to ∞). There was no significant difference in length of stay or mortality, or in the proportion of patients developing pulmonary complications, between the 2 groups. Adverse events (13.8% vs 29.3%; difference, -15.5% [95% CI, -20.7% to -10.3%]; P < .001) were more frequent with routine nebulization and mainly related to tachyarrhythmia (12.5% vs 25.9%; difference, -13.4% [95% CI, -18.4% to -8.4%]; P < .001) and agitation (0.2% vs 4.3%; difference, -4.1% [95% CI, -5.9% to -2.2%]; P < .001).

CONCLUSIONS AND RELEVANCE

Among ICU patients receiving invasive ventilation who were expected to not be extubated within 24 hours, on-demand compared with routine nebulization of acetylcysteine with salbutamol did not result in an inferior number of ventilator-free days. On-demand nebulization may be a reasonable alternative to routine nebulization.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02159196.