Effect of Low-Normal vs High-Normal Oxygenation Targets on Organ Dysfunction in Critically Ill Patients: A Randomized Clinical Trial

Oxygen therapy and noninvasive respiratory supports in acute hypoxemic respiratory failure: a narrative review

BACKGROUND

This narrative review was written by an expert panel to the members of the jury to help in the development of clinical practice guidelines on oxygen therapy.

RESULTS

According to the expert panel, acute hypoxemic respiratory failure was defined as PaO2 < 60 mm Hg or SpO2 < 90% on room air, or PaO2/FiO2 ≤ 300 mm Hg. Supplemental oxygen should be administered according to the monitoring of SpO2, with the aim at maintaining SpO2 above 92% and below 98%. Noninvasive respiratory supports are generally reserved for the most hypoxemic patients with the aim of relieving dyspnea. High-flow nasal cannula oxygen (HFNC) seems superior to conventional oxygen therapy (COT) as a means of avoiding intubation and may therefore be should probably be used as a first-line noninvasive respiratory support in patients requiring more than 6 L/min of oxygen or PaO2/FiO2 ≤ 200 mm Hg and a respiratory rate above 25 breaths/minute or clinical signs of respiratory distress, but with no benefits on mortality. Continuous positive airway pressure (CPAP) cannot currently be recommended as a first-line noninvasive respiratory support, since its beneficial effects on intubation remain uncertain. Despite older studies favoring noninvasive ventilation (NIV) over COT, recent clinical trials fail to show beneficial effects with NIV compared to HFNC. Therefore, there is no evidence to support the use of NIV or CPAP as first-line treatment if HFNC is available. Clinical trials do not support the hypothesis that noninvasive respiratory supports may lead to late intubation. The potential benefits of awake prone positioning on the risk of intubation in patients with COVID-19 cannot be extrapolated to patients with another etiology.

CONCLUSIONS

Whereas oxygen supplementation should be initiated for patients with acute hypoxemic respiratory failure defined as PaO2 below 60 mm Hg or SpO2 < 90% on room air, HFNC should be the first-line noninvasive respiratory support in patients with PaO2/FiO2 ≤ 200 mm Hg with increased respiratory rate. Further studies are needed to assess the potential benefits of CPAP, NIV through a helmet and awake prone position in patients with acute hypoxemic respiratory failure not related to COVID-19.

Effects of Oxygenation Targets on Mortality in Critically Ill Patients in Intensive Care Units: A Systematic Review and Meta-Analysis

BACKGROUND

The effects of oxygenation targets (partial pressure of arterial oxygen [Pa o2 ], arterial oxygen saturation [Sa o2 ]/peripheral oxygen saturation [Sp o2 ], or inspiratory oxygen concentration [Fi o2 ] on clinical outcomes in critically ill patients remains controversial. We reviewed the existing literature to assess the effects of lower and higher oxygenation targets on the mortality rates of critically ill intensive care unit (ICU) patients.

METHODS

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Web of Science databases were searched from their dates of inception to December 31, 2022, for randomized controlled trials (RCTs) comparing lower and higher oxygenation targets for critically ill patients ≥18 years of age undergoing mechanical ventilation, nasal cannula, oxygen mask, or high-flow oxygen therapy in the ICU. Data extraction was conducted independently, and RoB 2.0 software was used to evaluate the quality of each RCT. A random-effects model was used for the meta-analysis to calculate the relative risk (RR). We used the I 2 statistic as a measure of statistical heterogeneity. Certainty of evidence was assessed according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines.

RESULTS

We included 12 studies with a total of 7416 patients participating in RCTs. Oxygenation targets were extremely heterogeneous between studies. The meta-analysis found no differences in mortality between lower and higher oxygenation targets for critically ill ICU patients (relative risk [RR], 1.00; 95% confidence interval [CI], 0.93-1.09; moderate certainty). The incidence of serious adverse events (RR, 0.93; 95% CI, 0.85-1.00; high certainty), mechanical ventilation-free days through day 28 (mean difference [MD], -0.05; 95%CI, -1.23 to 1.13; low certainty), the number of patients requiring renal replacement therapy (RRT) (RR, 0.96; 95% CI, 0.84-1.10; low certainty), and ICU length of stay (MD, 1.05; 95% CI, -0.04 to 2.13; very low certainty) also did not differ among patients with lower or higher oxygenation targets.

CONCLUSIONS

Critically ill ICU patients ≥18 years of age managed with lower and higher oxygenation targets did not differ in terms of mortality, RRT need, mechanical ventilation-free days through day 28, or ICU length of stay. However, due to considerable heterogeneity between specific targets in individual studies, no conclusion can be drawn regarding the effect of oxygenation targets on ICU outcomes.

Pulmonary Events in ICU patients with hyperoxia: is it possible to relate arterial partial pressure of oxygen to coded diseases? A retrospective analysis

OBJECTIVE

Oxygen has been used liberally in ICUs for a long time to prevent hypoxia in ICU- patients. Current evidence suggests that paO2 >300 mmHg should be avoided, it remains uncertain whether an "optimal level" exists. We investigated how "mild" hyperoxia influences diseases and in-hospital mortality.

DESIGN

This is a retrospective study.

SETTING

112 mechanically ventilated ICU-patients were enrolled.

PATIENTS OR PARTICIPANTS

112 ventilated patients were included and categorized into two groups based on the median paO2 values measured in initial 24 h of mechanical ventilation: normoxia group (paO2 ≤ 100 mmHg, n = 43) and hyperoxia group patients (paO2 > 100 mmHg, n = 69).

INTERVENTIONS

No interventions were performed.

MAIN VARIABLES OF INTEREST

The primary outcome was the incidence of pulmonary events, the secondary outcomes included the incidence of other new organ dysfunctions and in-hospital mortality.

RESULTS

The baseline characteristics, such as age, body mass index, lactate levels, and severity of disease scores, were similar in both groups. There were no statistically significant differences in the incidence of pulmonary events, infections, and new organ dysfunctions between the groups. 27 out of 69 patients (39.1%) in the "mild" hyperoxia group and 12 out of 43 patients (27.9%) in the normoxia group died during their ICU or hospital stay (p = 0.54). The mean APACHE Score was 29.4 (SD 7.9) in the normoxia group and 30.0 (SD 6.7) in the hyperoxia group (p = 0.62).

CONCLUSIONS

We found no differences in pulmonary events, other coded diseases, and in-hospital mortality between both groups. It remains still unclear what the "best oxygen regime" is for intensive care patients.

Oxygen therapy in acute hypoxemic respiratory failure: guidelines from the SRLF-SFMU consensus conference

INTRODUCTION

Although largely used, the place of oxygen therapy and its devices in patients with acute hypoxemic respiratory failure (ARF) deserves to be clarified. The French Intensive Care Society (Société de Réanimation de Langue Française, SRLF) and the French Emergency Medicine Society (Société Française de Médecine d'Urgence, SFMU) organized a consensus conference on oxygen therapy in ARF (excluding acute cardiogenic pulmonary oedema and hypercapnic exacerbation of chronic obstructive diseases) in December 2023.

METHODS

A committee without any conflict of interest (CoI) with the subject defined 7 generic questions and drew up a list of sub questions according to the population, intervention, comparison and outcomes (PICO) model. An independent work group reviewed the literature using predefined keywords. The quality of the data was assessed using the GRADE methodology. Fifteen experts in the field from both societies proposed their own answers in a public session and answered questions from the jury (a panel of 16 critical-care and emergency medicine physicians, nurses and physiotherapists without any CoI) and the public. The jury then met alone for 48 h to write its recommendations.

RESULTS

The jury provided 22 statements answering 11 questions: in patients with ARF (1) What are the criteria for initiating oxygen therapy? (2) What are the targets of oxygen saturation? (3) What is the role of blood gas analysis? (4) When should an arterial catheter be inserted? (5) Should standard oxygen therapy, high-flow nasal cannula oxygen therapy (HFNC) or continuous positive airway pressure (CPAP) be preferred? (6) What are the indications for non-invasive ventilation (NIV)? (7) What are the indications for invasive mechanical ventilation? (8) Should awake prone position be used? (9) What is the role of physiotherapy? (10) Which criteria necessarily lead to ICU admission? (11) Which oxygenation device should be preferred for patients for whom a do-not-intubate decision has been made?

CONCLUSION

These recommendations should optimize the use of oxygen during ARF.

The physiological basis for individualized oxygenation targets in critically ill patients with circulatory shock

BACKGROUND

Circulatory shock, defined as decreased tissue perfusion, leading to inadequate oxygen delivery to meet cellular metabolic demands, remains a common condition with high morbidity and mortality. Rapid restitution and restoration of adequate tissue perfusion are the main treatment goals. To achieve this, current hemodynamic strategies focus on adjusting global physiological variables such as cardiac output (CO), hemoglobin (Hb) concentration, and arterial hemoglobin oxygen saturation (SaO2). However, it remains a challenge to identify optimal targets for these global variables that best support microcirculatory function. Weighting up the risks and benefits is especially difficult for choosing the amount of oxygen supplementation in critically ill patients. This review assesses the physiological basis for oxygen delivery to the tissue and provides an overview of the relevant literature to emphasize the importance of considering risks and benefits and support decision making at the bedside.

PHYSIOLOGICAL PREMISES

Oxygen must reach the tissue to enable oxidative phosphorylation. The human body timely detects hypoxia via different mechanisms aiming to maintain adequate tissue oxygenation. In contrast to the pulmonary circulation, where the main response to hypoxia is arteriolar vasoconstriction, the regulatory mechanisms of the systemic circulation aim to optimize oxygen availability in the tissues. This is achieved by increasing the capillary density in the microcirculation and the capillary hematocrit thereby increasing the capacity of oxygen diffusion from the red blood cells to the tissue. Hyperoxia, on the other hand, is associated with oxygen radical production, promoting cell death.

CURRENT STATE OF RESEARCH

Clinical trials in critically ill patients have primarily focused on comparing macrocirculatory endpoints and outcomes based on stroke volume and oxygenation targets. Some earlier studies have indicated potential benefits of conservative oxygenation. Recent trials show contradictory results regarding mortality, organ dysfunction, and ventilatory-free days. Empirical studies comparing various targets for SaO2, or partial pressure of oxygen indicate a U-shaped curve balancing positive and negative effects of oxygen supplementation.

CONCLUSION AND FUTURE DIRECTIONS

To optimize risk-benefit ratio of resuscitation measures in critically ill patients with circulatory shock in addition to individual targets for CO and Hb concentration, a primary aim should be to restore tissue perfusion and avoid hyperoxia. In the future, an individualized approach with microcirculatory targets will become increasingly relevant. Further studies are needed to define optimal targets.

The Comparative Impact of Liberal Versus Conservative Oxygenation in Critically Ill COVID-19 Patients: A Retrospective Study

Objectives Whether a higher or lower partial pressure of oxygen (PaO2) could impact outcomes in patients with coronavirus disease 2019 (COVID-19) remains a matter of debate. So, we planned this retrospective analysis to determine if a higher or lower partial pressure of oxygen in blood had any effect on outcomes in COVID-19 patients. Material and method The records of COVID-19 patients from the beginning of 2020 to the end of 2022 were scanned. Patients were sub-grouped into two groups based on the partial pressure of oxygen (PaO2) values on arterial blood gas (ABG), i.e., high PaO2 group, PaO2 value of 80-100 mm Hg, and low PaO2 group, PaO2 value of 60-80 mm Hg for the first 48 hours after the initiation of oxygenation and/or mechanical ventilation. The two groups were compared in terms of partial pressure of oxygen in arterial blood to the fraction of inspiratory oxygen (FiO2) concentration (P/F ratio), Sequential Organ Failure Assessment (SOFA) score at presentation and after 48 hours, and clinical outcomes, including mortality, time of mortality, extubation, acute kidney injury (AKI), and change in Glasgow Coma Scale (GCS). Results SOFA score was significantly higher in the low PaO2 group as compared to the high PaO2 group both at baseline (4.59 {1.79} versus 5.51 {1.15}; p-value: 0.005) and at 48 hours (3.06 {1.39} versus 5.11 {2.13}; p-value: 0.007). However, the change in SOFA score over 48 hours did not achieve statistical significance (-1.000 {0.97} versus 0.53 {2.34}; p-value: 0.257). Out of a total of 37 patients, 21 patients died in the high PaO2 group, while 18 patients died in the low PaO2 group. Conclusion Our study highlights that targeting either low or high arterial oxygen content while considering oxygen therapy for COVID-19 patients did not significantly alter the outcomes.

The critical care literature 2022

The number of critically ill patients that present to emergency departments across the world has risen steadily for nearly two decades. Despite a decrease in initial emergency department (ED) volumes early in the COVID-19 pandemic, the proportion of critically ill patients is now higher than pre-pandemic levels [1]. The emergency physician (EP) is often the first physician to evaluate and resuscitate a critically ill patient. In addition, EPs are frequently tasked with providing critical care long beyond the initial resuscitation. Prolonged boarding of critically ill patients in the ED is associated with increased duration of mechanical ventilation, increased intensive care unit (ICU) length of stay, increased hospital length of stay, increased medication-related adverse events, and increased in-hospital, 30-day, and 90-day mortality [2-4]. Given the continued increase in critically ill patients along with the increases in boarding critically ill patients in the ED, it is imperative for the EP to be knowledgeable about recent literature in resuscitation and critical care medicine, so that critically ill patients continue to receive evidence-based care. This review summarizes important articles published in 2022 that pertain to the resuscitation and management of select critically ill ED patients. These articles have been selected based on the authors review of key critical care, resuscitation, emergency medicine, and medicine journals and their opinion of the importance of study findings as it pertains to the care of the critically ill ED patient. Topics covered in this article include cardiac arrest, post-cardiac arrest care, rapid sequence intubation, mechanical ventilation, fluid resuscitation, and sepsis.

A new computed tomography score-based staging for melioidosis pneumonia to predict progression

Background

Melioidosis pneumonia, caused by the bacterium Burkholderia pseudomallei, is a serious infectious disease prevalent in tropical regions. Chest computed tomography (CT) has emerged as a valuable tool for assessing the severity and progression of lung involvement in melioidosis pneumonia. However, there persists a need for the quantitative assessment of CT characteristics and staging methodologies to precisely anticipate disease progression. This study aimed to quantitatively extract CT features and evaluate a CT score-based staging system in predicting the progression of melioidosis pneumonia.

Methods

This study included 97 patients with culture-confirmed melioidosis pneumonia who presented between January 2002 and December 2021. Lung segmentation and annotation of lesions (consolidation, nodules, and cavity) were used for feature extraction. The features, including the involved area, amount, and intensity, were extracted. The CT scores of the lesion features were defined by the feature importance weight and qualitative stage of melioidosis pneumonia. Gaussian process regression (GPR) was used to predict patients with severe or critical melioidosis pneumonia according to CT scores.

Results

The melioidosis pneumonia stages included acute stage (0-7 days), subacute stage (8-28 days), and chronic stage (>28 days). In the acute stage, the CT scores of all patients ranged from 2.5 to 6.5. In the subacute stage, the CT scores for the severe and mild patients were 3.0-7.0 and 2.0-5.0, respectively. In the chronic stage, the CT score of the mild patients fluctuated approximately between 2.5 and 3.5 in a linear distribution. Consolidation was the most common type of lung lesion in those with melioidosis pneumonia. Between stages I and II, the percentage of severe scans with nodules dropped from 72.22% to 47.62% (P<0.05), and the percentage of severe scans with cavities significantly increased from 16.67% to 57.14% (P<0.05). The GPR optimization function yielded area under the receiver operating characteristic curves of 0.71 for stage I, 0.92 for stage II, and 0.87 for all stages.

Conclusions

In patients with melioidosis pneumonia, it is reasonable to divide the period (the whole progression of melioidosis pneumonia) into three stages to determine the prognosis.

Effects of a lower versus a higher oxygenation target in intensive care unit patients with chronic obstructive pulmonary disease and acute hypoxaemic respiratory failure: a subgroup analysis of a randomised clinical trial

Background

Oxygen supplementation is ubiquitous in intensive care unit (ICU) patients with chronic obstructive pulmonary disease (COPD) and acute hypoxaemia, but the optimal oxygenation target has not been established.

Methods

This was a pre-planned subgroup analysis of the Handling Oxygenation Targets in the ICU (HOT-ICU) trial, which allocated patients with acute hypoxaemia to a lower oxygenation target (partial pressure of arterial oxygen [Pao2] of 8 kPa) vs a higher target (Pao2 of 12 kPa) during ICU admission, for up to 90 days; the allocation was stratified for presence or absence of COPD. Here, we report key outcomes for patients with COPD.

Results

The HOT-ICU trial enrolled 2928 patients of whom 563 had COPD; 277 were allocated to the lower and 286 to the higher oxygenation group. After allocation, the median Pao2 was 9.1 kPa (inter-quartile range 8.7-9.9) in the lower group vs 12.1 kPa (11.2-12.9) in the higher group. Data for arterial carbon dioxide (Paco2) were available for 497 patients (88%) with no between-group difference in time-weighted average; median Paco2 6.0 kPa (5.2-7.2) in the lower group vs 6.2 kPa (5.4-7.3) in the higher group. At 90 days, 122/277 patients (44%) in the lower oxygenation group had died vs 132/285 patients (46%) in the higher (relative risk 0.98; 95% confidence interval 0.82-1.17; P=0.67). No statistically significant differences were found in any secondary outcome.

Conclusions

In ICU patients with COPD and acute hypoxaemia, a lower vs a higher oxygenation target did not reduce mortality. There were no between-group differences in Paco2 or in secondary outcomes.

Clinical trial registration

NCT03174002, EudraCT number 2017-000632-34.

Hyperoxemia in invasively ventilated COVID-19 patients-Insights from the PRoVENT-COVID study

OBJECTIVE

We determined the prevalences of hyperoxemia and excessive oxygen use, and the epidemiology, ventilation characteristics and outcomes associated with hyperoxemia in invasively ventilated patients with coronavirus disease 2019 (COVID-19).

METHODS

Post hoc analysis of a national, multicentre, observational study in 22 ICUs. Patients were classified in the first two days of invasive ventilation as 'hyperoxemic' or 'normoxemic'. The co-primary endpoints were prevalence of hyperoxemia (PaO2 > 90 mmHg) and prevalence of excessive oxygen use (FiO2 ≥ 60% while PaO2 > 90 mmHg or SpO2 > 92%). Secondary endpoints included ventilator settings and ventilation parameters, duration of ventilation, length of stay (LOS) in ICU and hospital, and mortality in ICU, hospital, and at day 28 and 90. We used propensity matching to control for observed confounding factors that may influence endpoints.

RESULTS

Of 851 COVID-19 patients, 225 (26.4%) were classified as hyperoxemic. Excessive oxygen use occurred in 385 (45.2%) patients. Acute respiratory distress syndrome (ARDS) severity was lowest in hyperoxemic patients. Hyperoxemic patients were ventilated with higher positive end-expiratory pressure (PEEP), while rescue therapies for hypoxemia were applied more often in normoxemic patients. Neither in the unmatched nor in the matched analysis were there differences between hyperoxemic and normoxemic patients with regard to any of the clinical outcomes.

CONCLUSION

In this cohort of invasively ventilated COVID-19 patients, hyperoxemia occurred often and so did excessive oxygen use. The main differences between hyperoxemic and normoxemic patients were ARDS severity and use of PEEP. Clinical outcomes were not different between hyperoxemic and normoxemic patients.

Association between arterial oxygen and mortality across critically ill patients with hematologic malignancies: results from an international collaborative network

PURPOSE

Patients with hematological malignancies are at high risk for life-threatening complications. To date, little attention has been paid to the impact of hyperoxemia and excess oxygen use on mortality. The aim of this study was to investigate the association between partial pressure of arterial oxygen (PaO2) and 28-day mortality in critically ill patients with hematologic malignancies.

METHODS

Data from three international cohorts (Europe, Canada, Oceania) of patients who received respiratory support (noninvasive ventilation, high-flow nasal cannula, invasive mechanical ventilation) were obtained. We used mixed-effect Cox models to investigate the association between day one PaO2 or excess oxygen use (inspired fraction of oxygen ≥ 0.6 with PaO2 > 100 mmHg) on day-28 mortality.

RESULTS

11,249 patients were included. On day one, 5716 patients (50.8%) had normoxemia (60 ≤ PaO2 ≤ 100 mmHg), 1454 (12.9%) hypoxemia (PaO2 < 60 mmHg), and 4079 patients (36.3%) hyperoxemia (PaO2 > 100 mmHg). Excess oxygen was used in 2201 patients (20%). Crude day-28 mortality rate was 40.6%. There was a significant association between PaO2 and day-28 mortality with a U-shaped relationship (p < 0.001). Higher PaO2 levels (> 100 mmHg) were associated with day-28 mortality with a dose-effect relationship. Subgroup analyses showed an association between hyperoxemia and mortality in patients admitted with neurological disorders; however, the opposite relationship was seen across those admitted with sepsis and neutropenia. Excess oxygen use was also associated with subsequent day-28 mortality (adjusted hazard ratio (aHR) [95% confidence interval (CI)]: 1.11[1.04-1.19]). This result persisted after propensity score analysis (matched HR associated with excess oxygen:1.31 [1.20-1.1.44]).

CONCLUSION

In critically-ill patients with hematological malignancies, exposure to hyperoxemia and excess oxygen use were associated with increased mortality, with variable magnitude across subgroups. This might be a modifiable factor to improve mortality.

Conservative versus liberal oxygen therapy for intensive care unit patients: meta-analysis of randomized controlled trials

BACKGROUND

It remains unclear whether conservative oxygen therapy (COT) or liberal oxygen therapy (LOT) is more beneficial to the clinical outcomes of intensive care unit (ICU) patients. We systematically reviewed the efficacy and safety of conservative versus liberal oxygen therapy for ICU patients.

METHODS

We systematically searched PubMed, Embase, Web of Science, Scopus, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, MedRxiv, and BioRxiv for reports on randomized controlled trials (RCTs) that compared the effects of COT versus LOT on the clinical outcomes of ICU patients published in English before April 2024. The primary outcome was the mortality rate, secondary outcomes included ICU and hospital length of stay, days free from mechanical ventilation support (MVF), vasopressor-free time (VFT), and adverse events.

RESULTS

In all, 13 RCTs involving 10,632 patients were included in analyses. Meta-analysis showed COT did not reduce mortality at 30-day (risk ratio [RR] = 1.01, 95% confidence interval [CI] 0.94 to 1.09, I2 = 42%, P = 0.78), 90-day (RR = 1.01, 95% CI 0.95 to 1.08, I2 = 9%, P = 0.69), or longest follow-up (RR = 1.00, 95% CI 0.95 to 1.06, I2 = 22%, P = 0.95) compared to LOT in ICU patients. In subgroup analyses, no significant difference was observed between the two groups in terms of the different ICU, baseline P/F, and actual PaO2. In addition, COT did not affect ICU length of stay, hospital length of stay, or VFT, it only affected MVF days.

CONCLUSIONS

COT did not reduce all-cause mortality in ICU patients. Further RCTs are urgently needed to confirm the impact of COT strategy on specific populations.

Individualized Treatment Effects of Oxygen Targets in Mechanically Ventilated Critically Ill Adults

Importance

Among critically ill adults, randomized trials have not found oxygenation targets to affect outcomes overall. Whether the effects of oxygenation targets differ based on an individual's characteristics is unknown.

Objective

To determine whether an individual's characteristics modify the effect of lower vs higher peripheral oxygenation-saturation (Spo2) targets on mortality.

Design, Setting, and Participants

A machine learning model to predict the effect of treatment with a lower vs higher Spo2 target on mortality for individual patients was derived in the Pragmatic Investigation of Optimal Oxygen Targets (PILOT) trial and externally validated in the Intensive Care Unit Randomized Trial Comparing Two Approaches to Oxygen Therapy (ICU-ROX) trial. Critically ill adults received invasive mechanical ventilation in an intensive care unit (ICU) in the United States between July 2018 and August 2021 for PILOT (n = 1682) and in 21 ICUs in Australia and New Zealand between September 2015 and May 2018 for ICU-ROX (n = 965).

Exposures

Randomization to a lower vs higher Spo2 target group.

Main Outcome and Measure

28-Day mortality.

Results

In the ICU-ROX validation cohort, the predicted effect of treatment with a lower vs higher Spo2 target for individual patients ranged from a 27.2% absolute reduction to a 34.4% absolute increase in 28-day mortality. For example, patients predicted to benefit from a lower Spo2 target had a higher prevalence of acute brain injury, whereas patients predicted to benefit from a higher Spo2 target had a higher prevalence of sepsis and abnormally elevated vital signs. Patients predicted to benefit from a lower Spo2 target experienced lower mortality when randomized to the lower Spo2 group, whereas patients predicted to benefit from a higher Spo2 target experienced lower mortality when randomized to the higher Spo2 group (likelihood ratio test for effect modification P = .02). The use of a Spo2 target predicted to be best for each patient, instead of the randomized Spo2 target, would have reduced the absolute overall mortality by 6.4% (95% CI, 1.9%-10.9%).

Conclusion and relevance

Oxygenation targets that are individualized using machine learning analyses of randomized trials may reduce mortality for critically ill adults. A prospective trial evaluating the use of individualized oxygenation targets is needed.

Individualized Thresholds of Hypoxemia and Hyperoxemia and their Effect on Outcome in Acute Brain Injured Patients: A Secondary Analysis of the ENIO Study

BACKGROUND

In acute brain injury (ABI), the effects of hypoxemia as a potential cause of secondary brain damage and poor outcome are well documented, whereas the impact of hyperoxemia is unclear. The primary aim of this study was to assess the episodes of hypoxemia and hyperoxemia in patients with ABI during the intensive care unit (ICU) stay and to determine their association with in-hospital mortality. The secondary aim was to identify the optimal thresholds of arterial partial pressure of oxygen (PaO2) predicting in-hospital mortality.

METHODS

We conducted a secondary analysis of a prospective multicenter observational cohort study. Adult patients with ABI (traumatic brain injury, subarachnoid aneurysmal hemorrhage, intracranial hemorrhage, ischemic stroke) with available data on PaO2 during the ICU stay were included. Hypoxemia was defined as PaO2 < 80 mm Hg, normoxemia was defined as PaO2 between 80 and 120 mm Hg, mild/moderate hyperoxemia was defined as PaO2 between 121 and 299 mm Hg, and severe hyperoxemia was defined as PaO2 levels ≥ 300 mm Hg.

RESULTS

A total of 1,407 patients were included in this study. The mean age was 52 (±18) years, and 929 (66%) were male. Over the ICU stay, the fractions of patients in the study cohort who had at least one episode of hypoxemia, mild/moderate hyperoxemia, and severe hyperoxemia were 31.3%, 53.0%, and 1.7%, respectively. PaO2 values below 92 mm Hg and above 156 mm Hg were associated with an increased probability of in-hospital mortality. Differences were observed among subgroups of patients with ABI, with consistent effects only seen in patients without traumatic brain injury.

CONCLUSIONS

In patients with ABI, hypoxemia and mild/moderate hyperoxemia were relatively frequent. Hypoxemia and hyperoxemia during ICU stay may influence in-hospital mortality. However, the small number of oxygen values collected represents a major limitation of the study.

Comparison of mortality and outcomes of four respiratory viruses in the intensive care unit: a multicenter retrospective study

This retrospective study aimed to compare the mortality and burden of respiratory syncytial virus (RSV group), SARS-CoV-2 (COVID-19 group), non-H1N1 (Seasonal influenza group) and H1N1 influenza (H1N1 group) in adult patients admitted to intensive care unit (ICU) with respiratory failure. A total of 807 patients were included. Mortality was compared between the four following groups: RSV, COVID-19, seasonal influenza, and H1N1 groups. Patients in the RSV group had significantly more comorbidities than the other patients. At admission, patients in the COVID-19 group were significantly less severe than the others according to the simplified acute physiology score-2 (SAPS-II) and sepsis-related organ failure assessment (SOFA) scores. Using competing risk regression, COVID-19 (sHR = 1.61; 95% CI 1.10; 2.36) and H1N1 (sHR = 1.87; 95% CI 1.20; 2.93) were associated with a statistically significant higher mortality while seasonal influenza was not (sHR = 0.93; 95% CI 0.65; 1.31), when compared to RSV. Despite occurring in more severe patients, RSV and seasonal influenza group appear to be associated with a more favorable outcome than COVID-19 and H1N1 groups.

Higher versus lower oxygenation targets in adult ICU patients: A rapid practice guideline

The aim of this Intensive Care Medicine Rapid Practice Guideline (ICM-RPG) was to provide evidence-based clinical guidance about the use of higher versus lower oxygenation targets for adult patients in the intensive care unit (ICU). The guideline panel comprised 27 international panelists, including content experts, ICU clinicians, methodologists, and patient representatives. We adhered to the methodology for trustworthy clinical practice guidelines, including the use of the Grading of Recommendations Assessment, Development, and Evaluation approach to assess the certainty of evidence, and used the Evidence-to-Decision framework to generate recommendations. A recently published updated systematic review and meta-analysis constituted the evidence base. Through teleconferences and web-based discussions, the panel provided input on the balance and magnitude of the desirable and undesirable effects, the certainty of evidence, patients' values and preferences, costs and resources, equity, feasibility, acceptability, and research priorities. The updated systematic review and meta-analysis included data from 17 randomized clinical trials with 10,248 participants. There was little to no difference between the use of higher versus lower oxygenation targets for all outcomes with available data, including all-cause mortality, serious adverse events, stroke, functional outcomes, cognition, and health-related quality of life (very low certainty of evidence). The panel felt that values and preferences, costs and resources, and equity favored the use of lower oxygenation targets. The ICM-RPG panel issued one conditional recommendation against the use of higher oxygenation targets: "We suggest against the routine use of higher oxygenation targets in adult ICU patients (conditional recommendation, very low certainty of evidence). Remark: an oxygenation target of SpO2 88%-92% or PaO2 8 kPa/60 mmHg is relevant and safe for most adult ICU patients."

State of the art: Monitoring of the respiratory system during veno-venous extracorporeal membrane oxygenation

Monitoring the patient receiving veno-venous extracorporeal membrane oxygenation (VV ECMO) is challenging due to the complex physiological interplay between native and membrane lung. Understanding these interactions is essential to understand the utility and limitations of different approaches to respiratory monitoring during ECMO. We present a summary of the underlying physiology of native and membrane lung gas exchange and describe different tools for titrating and monitoring gas exchange during ECMO. However, the most important role of VV ECMO in severe respiratory failure is as a means of avoiding further ergotrauma. Although optimal respiratory management during ECMO has not been defined, over the last decade there have been advances in multimodal respiratory assessment which have the potential to guide care. We describe a combination of imaging, ventilator-derived or invasive lung mechanic assessments as a means to individualise management during ECMO.

Positive single-center randomized trials and subsequent multicenter randomized trials in critically ill patients: a systematic review

BACKGROUND

It is unclear how often survival benefits observed in single-center randomized controlled trials (sRCTs) involving critically ill patients are confirmed by subsequent multicenter randomized controlled trials (mRCTs). We aimed to perform a systemic literature review of sRCTs with a statistically significant mortality reduction and to evaluate whether subsequent mRCTs confirmed such reduction.

METHODS

We searched PubMed for sRCTs published in the New England Journal of Medicine, JAMA, or Lancet, from inception until December 31, 2016. We selected studies reporting a statistically significant mortality decrease using any intervention (drug, technique, or strategy) in adult critically ill patients. We then searched for subsequent mRCTs addressing the same research question tested by the sRCT. We compared the concordance of results between sRCTs and mRCTs when any mRCT was available. We registered this systematic review in the PROSPERO International Prospective Register of Systematic Reviews (CRD42023455362).

RESULTS

We identified 19 sRCTs reporting a significant mortality reduction in adult critically ill patients. For 16 sRCTs, we identified at least one subsequent mRCT (24 trials in total), while the interventions from three sRCTs have not yet been addressed in a subsequent mRCT. Only one out of 16 sRCTs (6%) was followed by a mRCT replicating a significant mortality reduction; 14 (88%) were followed by mRCTs with no mortality difference. The positive finding of one sRCT (6%) on intensive glycemic control was contradicted by a subsequent mRCT showing a significant mortality increase. Of the 14 sRCTs referenced at least once in international guidelines, six (43%) have since been either removed or suggested against in the most recent versions of relevant guidelines.

CONCLUSION

Mortality reduction shown by sRCTs is typically not replicated by mRCTs. The findings of sRCTs should be considered hypothesis-generating and should not contribute to guidelines.

The effect of conservative oxygen therapy on mortality in adult critically ill patients: A systematic review and meta-analysis of randomised controlled trials

Background

Oxygen is the commonest intervention provided to critically ill patients requiring mechanical ventilation. Despite this, it is unclear how much oxygen should be administered to patients in order to promote the best clinical outcomes and it has been suggested that a strategy of conservative oxygen therapy (COT) may be advantageous. We therefore sought to answer the question of whether COT versus usual or liberal oxygen therapy was beneficial to adult patients receiving mechanical ventilation on an intensive care unit (ICU) by performing a systematic review and meta-analysis.

Methods

Studies were included if they were randomised controlled trials comparing COT to liberal or usual oxygen therapy strategies in acutely ill adults (aged ⩾18 years) admitted to an ICU, and reported an outcome of interest. Studies were excluded if they were limited to a specific single disease diagnosis. The review was registered on PROSPERO (CRD42022308436). Risk of bias was assessed using a modified Cochrane Risk of Bias assessment tool. Effect estimates were pooled using a random effects model with the between study variance estimated using restricted maximum likelihood and standard errors calculated using the method of Hartung-Knapp/Sidik-Jonkman. Between study heterogeneity was quantified using the I2 statistic. The certainty in the body of evidence was assessed using GRADE criteria.

Results

Nine eligible studies with 5727 participants fulfilled all eligibility criteria. Trials varied in their definitions of COT and liberal or usual oxygen therapy. The pooled estimate of risk ratio for 90 day mortality for COT versus comparator was 0.99 (95% confidence interval 0.88-1.12, 95% prediction interval 0.82-1.21). There was low heterogeneity among studies (I2 = 22.4%). The finding that mortality was similar for patients managed with COT or usual/liberal oxygen therapy was graded as moderate certainty.

Conclusions

In critically ill adults admitted to an ICU, COT is neither beneficial nor harmful when compared to usual or liberal oxygen therapy. Trials to date have been inconsistent in defining both COT and liberal or usual oxygen therapy, which may have had an impact on the results of this meta-analysis. Future research should focus on unifying definitions and outcome measures.

Effects of Conservative Oxygen Therapy versus Conventional Oxygen Therapy on the Mortality in ICU Patients: A Meta-Analysis

Objective

To compare the effects of conservative oxygen therapy and conventional oxygen therapy on the mortality of critically ill patients in ICU.

Methods

Searching for randomized controlled clinical trials (RCT) on the effect of conservative oxygen therapy and conventional oxygen therapy on the mortality of critically ill patients in computer databases, including PubMed, Embase, Cochrane Library, CNKI, VIP, and Wanfang, with postdate before August 2022. We have two researchers evaluating the quality of the literature included and extracting data as per the inclusion and exclusion criteria and then analyzed it with RevMan 5.4 statistical software. Primary outcome included short-term mortality (28-day mortality or ICU mortality); secondary outcome included 90-day mortality, ICU length of stay, hospital length of stay, incidence of new organ dysfunction in ICU, incidence of new infection in ICU, and incidence of ICUAW.

Results

A total of 5779 subjects were included in 10 articles, including 2886 in the conservative oxygen therapy group and 2893 in the conventional oxygen therapy group. The meta-analysis showed that conservative oxygen therapy had an advantage over conventional oxygen therapy in terms of short-term mortality (P=0.03). Subgroup analysis based on different conservative oxygen targets showed that this advantage was statistically significant when the target is set above 90% (RR = 0.76, 95% CI = 0.62∼0.94, P=0.01), while there was no significant difference between conservative oxygen therapy and conventional oxygen therapy when the target is set below 90% (RR = 0.95, 95% CI = 0.79∼1.16, P=0.63). In addition, in terms of the incidence of new infections in the ICU (P=0.03) and the incidence of ICUAW (P=0.03), conservative oxygen therapy also had advantages over conventional oxygen therapy, and the difference was statistically significant. But in terms of 90-day mortality (P=0.61), ICU length of stay (P=0.96), hospital length of stay (P=0.47), and incidence of new organ dysfunction in ICU (P=0.61), there was no significant difference between conservative oxygen therapy and conventional oxygen therapy.

Conclusion

Compared with conventional oxygen therapy, conservative oxygen therapy can reduce the short-term mortality of severe patients, especially when the conservative oxygen therapy target is set above 90%. And it can also reduce the incidence of ICU new infections and ICUAW, while having no effect on 90-day mortality, ICU length of stay, and hospital length of stay.

Restrictive versus high-dose oxygenation strategy in post-arrest management following adult non-traumatic cardiac arrest: a meta-analysis

PURPOSE

Neurological damage is the main cause of death or withdrawal of care in comatose survivors of cardiac arrest (CA). Hypoxemia and hyperoxemia following CA were described as potentially harmful, but reports were inconsistent. Current guidelines lack specific oxygen targets after return of spontaneous circulation (ROSC).

OBJECTIVES

The current meta-analysis assessed the effects of restrictive compared to high-dose oxygenation strategy in survivors of CA.

METHODS

A structured literature search was performed. Randomized controlled trials (RCTs) comparing two competing oxygenation strategies in post-ROSC management after CA were eligible. The primary end point was short-term survival (≤ 90 days). The meta-analysis was prospectively registered in PROSPERO database (CRD42023444513).

RESULTS

Eight RCTs enrolling 1941 patients were eligible. Restrictive oxygenation was applied to 964 patients, high-dose regimens were used in 977 participants. Short-term survival rate was 55.7% in restrictive and 56% in high-dose oxygenation group (8 trials, RR 0.99, 95% CI 0.90 to 1.10, P = 0.90, I2 = 18%, no difference). No evidence for a difference was detected in survival to hospital discharge (5 trials, RR 0.98, 95% CI 0.79 to 1.21, P = 0.84, I2 = 32%). Episodes of hypoxemia more frequently occurred in restrictive oxygenation group (4 trials, RR 2.06, 95% CI 1.47 to 2.89, P = 0.004, I2 = 13%).

CONCLUSION

Restrictive and high-dose oxygenation strategy following CA did not result in differences in short-term or in-hospital survival. Restrictive oxygenation strategy may increase episodes of hypoxemia, even with restrictive oxygenation targets exceeding intended saturation levels, but the clinical relevance is unknown. There is still a wide gap in the evidence of optimized oxygenation in post-ROSC management and specific targets cannot be concluded from the current evidence.

Conservative versus Liberal Oxygenation Targets in Intensive Care Unit Patients (ICONIC): A Randomized Clinical Trial

Rationale: Supplemental oxygen is widely administered to ICU patients, but appropriate oxygenation targets remain unclear. Objectives: This study aimed to determine whether a low-oxygenation strategy would lower 28-day mortality compared with a high-oxygenation strategy. Methods: This randomized multicenter trial included mechanically ventilated ICU patients with an expected ventilation duration of at least 24 hours. Patients were randomized 1:1 to a low-oxygenation (PaO2, 55-80 mm Hg; or oxygen saturation as measured by pulse oximetry, 91-94%) or high-oxygenation (PaO2, 110-150 mm Hg; or oxygen saturation as measured by pulse oximetry, 96-100%) target until ICU discharge or 28 days after randomization, whichever came first. The primary outcome was 28-day mortality. The study was stopped prematurely because of the COVID-19 pandemic when 664 of the planned 1,512 patients were included. Measurements and Main Results: Between November 2018 and November 2021, a total of 664 patients were included in the trial: 335 in the low-oxygenation group and 329 in the high-oxygenation group. The median achieved PaO2 was 75 mm Hg (interquartile range, 70-84) and 115 mm Hg (interquartile range, 100-129) in the low- and high-oxygenation groups, respectively. At Day 28, 129 (38.5%) and 114 (34.7%) patients had died in the low- and high-oxygenation groups, respectively (risk ratio, 1.11; 95% confidence interval, 0.9-1.4; P = 0.30). At least one serious adverse event was reported in 12 (3.6%) and 17 (5.2%) patients in the low- and high-oxygenation groups, respectively. Conclusions: Among mechanically ventilated ICU patients with an expected mechanical ventilation duration of at least 24 hours, using a low-oxygenation strategy did not result in a reduction of 28-day mortality compared with a high-oxygenation strategy. Clinical trial registered with the National Trial Register and the International Clinical Trials Registry Platform (NTR7376).

Higher versus lower fractions of inspired oxygen or targets of arterial oxygenation for adults admitted to the intensive care unit

BACKGROUND

This is an updated review concerning 'Higher versus lower fractions of inspired oxygen or targets of arterial oxygenation for adults admitted to the intensive care unit'. Supplementary oxygen is provided to most patients in intensive care units (ICUs) to prevent global and organ hypoxia (inadequate oxygen levels). Oxygen has been administered liberally, resulting in high proportions of patients with hyperoxemia (exposure of tissues to abnormally high concentrations of oxygen). This has been associated with increased mortality and morbidity in some settings, but not in others. Thus far, only limited data have been available to inform clinical practice guidelines, and the optimum oxygenation target for ICU patients is uncertain. Because of the publication of new trial evidence, we have updated this review.

OBJECTIVES

To update the assessment of benefits and harms of higher versus lower fractions of inspired oxygen (FiO2) or targets of arterial oxygenation for adults admitted to the ICU.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Science Citation Index Expanded, BIOSIS Previews, and LILACS. We searched for ongoing or unpublished trials in clinical trial registers and scanned the reference lists and citations of included trials. Literature searches for this updated review were conducted in November 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared higher versus lower FiO2 or targets of arterial oxygenation (partial pressure of oxygen (PaO2), peripheral or arterial oxygen saturation (SpO2 or SaO2)) for adults admitted to the ICU. We included trials irrespective of publication type, publication status, and language. We excluded trials randomising participants to hypoxaemia (FiO2 below 0.21, SaO2/SpO2 below 80%, or PaO2 below 6 kPa) or to hyperbaric oxygen, and cross-over trials and quasi-randomised trials.

DATA COLLECTION AND ANALYSIS

Four review authors independently, and in pairs, screened the references identified in the literature searches and extracted the data. Our primary outcomes were all-cause mortality, the proportion of participants with one or more serious adverse events (SAEs), and quality of life. We analysed all outcomes at maximum follow-up. Only three trials reported the proportion of participants with one or more SAEs as a composite outcome. However, most trials reported on events categorised as SAEs according to the International Conference on Harmonisation Good Clinical Practice (ICH-GCP) criteria. We, therefore, conducted two analyses of the effect of higher versus lower oxygenation strategies using 1) the single SAE with the highest reported proportion in each trial, and 2) the cumulated proportion of participants with an SAE in each trial. Two trials reported on quality of life. Secondary outcomes were lung injury, myocardial infarction, stroke, and sepsis. No trial reported on lung injury as a composite outcome, but four trials reported on the occurrence of acute respiratory distress syndrome (ARDS) and five on pneumonia. We, therefore, conducted two analyses of the effect of higher versus lower oxygenation strategies using 1) the single lung injury event with the highest reported proportion in each trial, and 2) the cumulated proportion of participants with ARDS or pneumonia in each trial. We assessed the risk of systematic errors by evaluating the risk of bias in the included trials using the Risk of Bias 2 tool. We used the GRADEpro tool to assess the overall certainty of the evidence. We also evaluated the risk of publication bias for outcomes reported by 10b or more trials.

MAIN RESULTS

We included 19 RCTs (10,385 participants), of which 17 reported relevant outcomes for this review (10,248 participants). For all-cause mortality, 10 trials were judged to be at overall low risk of bias, and six at overall high risk of bias. For the reported SAEs, 10 trials were judged to be at overall low risk of bias, and seven at overall high risk of bias. Two trials reported on quality of life, of which one was judged to be at overall low risk of bias and one at high risk of bias for this outcome. Meta-analysis of all trials, regardless of risk of bias, indicated no significant difference from higher or lower oxygenation strategies at maximum follow-up with regard to mortality (risk ratio (RR) 1.01, 95% confidence interval (C)I 0.96 to 1.06; I2 = 14%; 16 trials; 9408 participants; very low-certainty evidence); occurrence of SAEs: the highest proportion of any specific SAE in each trial RR 1.01 (95% CI 0.96 to 1.06; I2 = 36%; 9466 participants; 17 trials; very low-certainty evidence), or quality of life (mean difference (MD) 0.5 points in participants assigned to higher oxygenation strategies (95% CI -2.75 to 1.75; I2 = 34%, 1649 participants; 2 trials; very low-certainty evidence)). Meta-analysis of the cumulated number of SAEs suggested benefit of a lower oxygenation strategy (RR 1.04 (95% CI 1.02 to 1.07; I2 = 74%; 9489 participants; 17 trials; very low certainty evidence)). However, trial sequential analyses, with correction for sparse data and repetitive testing, could reject a relative risk increase or reduction of 10% for mortality and the highest proportion of SAEs, and 20% for both the cumulated number of SAEs and quality of life. Given the very low-certainty of evidence, it is necessary to interpret these findings with caution. Meta-analysis of all trials indicated no statistically significant evidence of a difference between higher or lower oxygenation strategies on the occurrence of lung injuries at maximum follow-up (the highest reported proportion of lung injury RR 1.08, 95% CI 0.85 to 1.38; I2 = 0%; 2048 participants; 8 trials; very low-certainty evidence). Meta-analysis of all trials indicated harm from higher oxygenation strategies as compared with lower on the occurrence of sepsis at maximum follow-up (RR 1.85, 95% CI 1.17 to 2.93; I2 = 0%; 752 participants; 3 trials; very low-certainty evidence). Meta-analysis indicated no differences regarding the occurrences of myocardial infarction or stroke.

AUTHORS' CONCLUSIONS

In adult ICU patients, it is still not possible to draw clear conclusions about the effects of higher versus lower oxygenation strategies on all-cause mortality, SAEs, quality of life, lung injuries, myocardial infarction, stroke, and sepsis at maximum follow-up. This is due to low or very low-certainty evidence.

Effects of intraoperative inspired oxygen fraction (FiO2 0.3 vs 0.8) on patients undergoing off-pump coronary artery bypass grafting: the CARROT multicenter, cluster-randomized trial

BACKGROUND

To maintain adequate oxygenation is of utmost importance in intraoperative care. However, clinical evidence supporting specific oxygen levels in distinct surgical settings is lacking. This study aimed to compare the effects of 30% and 80% oxygen in off-pump coronary artery bypass grafting (OPCAB).

METHODS

This multicenter trial was conducted in three tertiary hospitals from August 2019 to August 2021. Patients undergoing OPCAB were cluster-randomized to receive either 30% or 80% oxygen intraoperatively, based on the month when the surgery was performed. The primary endpoint was the length of hospital stay. Intraoperative hemodynamic data were also compared.

RESULTS

A total of 414 patients were cluster-randomized. Length of hospital stay was not different in the 30% oxygen group compared to the 80% oxygen group (median, 7.0 days vs 7.0 days; the sub-distribution hazard ratio, 0.98; 95% confidence interval [CI] 0.83-1.16; P = 0.808). The incidence of postoperative acute kidney injury was significantly higher in the 30% oxygen group than in the 80% oxygen group (30.7% vs 19.4%; odds ratio, 1.94; 95% CI 1.18-3.17; P = 0.036). Intraoperative time-weighted average mixed venous oxygen saturation was significantly higher in the 80% oxygen group (74% vs 64%; P < 0.001). The 80% oxygen group also had a significantly greater intraoperative time-weighted average cerebral regional oxygen saturation than the 30% oxygen group (56% vs 52%; P = 0.002).

CONCLUSIONS

In patients undergoing OPCAB, intraoperative administration of 80% oxygen did not decrease the length of hospital stay, compared to 30% oxygen, but may reduce postoperative acute kidney injury. Moreover, compared to 30% oxygen, intraoperative use of 80% oxygen improved oxygen delivery in patients undergoing OPCAB. Trial registration ClinicalTrials.gov (NCT03945565; April 8, 2019).

Lower Versus Higher Oxygenation Targets for Critically Ill Patients: A Systematic Review

Supplemental oxygen is a standard therapeutic intervention for critically ill patients such as patients suffering from cardiac arrest, myocardial ischemia, traumatic brain injury, and stroke. However, the optimal oxygenation targets remain elusive owing to the paucity and inconsistencies in the relevant literature. A comprehensive analysis of the available scientific evidence was performed to establish the relative efficacy of the lower and higher oxygenation targets. A systematic literature search was conducted in PubMed, MEDLINE, and Scopus databases from 2010 to 2023. Further, Google Scholar was also searched. Studies evaluating the efficacy of oxygenation targets and the associated clinical outcomes were included. Studies that included participants with hyperbaric oxygen therapy, chronic respiratory diseases, or extracorporeal life support were excluded. The literature search was performed by two blinded reviewers. A total of 19 studies were included in this systemic review, including 72,176 participants. A total of 14 randomized control trials were included. A total of 12 studies investigated the efficacy of lower and higher oxygenation targets in ICU-admitted patients, and seven were assessed in patients with acute myocardial infarction and stroke. For ICU patients, the evidence was conflicting, with some studies showing the efficacy of conservative oxygen therapy while others reported no difference. Overall, nine studies concluded that lower oxygen targets are favorable. However, most studies (n=4) in stroke and myocardial infarction patients showed no difference in lower or higher oxygenation targets whereas only two supported lower oxygenation targets. Available evidence suggests that lower oxygenation targets result in either improved or equivalent clinical outcomes compared with higher oxygenation targets.

Early Plasmapheresis Among Patients With Hypertriglyceridemia-Associated Acute Pancreatitis

Importance

The incidence of hypertriglyceridemia-associated acute pancreatitis (HTG-AP) is increasing. Plasmapheresis is theoretically effective in removing triglyceride from plasma, but whether it confers clinical benefits is unclear.

Objective

To assess the association between plasmapheresis and the incidence and duration of organ failure among patients with HTG-AP.

Design, Setting, and Participants

This is an a priori analysis of data from a multicenter, prospective cohort study with patients enrolled from 28 sites across China. Patients with HTG-AP were admitted within 72 hours from the disease onset. The first patient was enrolled on November 7th, 2020, and the last on November 30th, 2021. The follow-up of the 300th patient was completed on January 30th, 2022. Data were analyzed from April to May 2022.

Exposures

Receiving plasmapheresis. The choice of triglyceride-lowering therapies was at the discretion of the treating physicians.

Main Outcomes and Measures

The primary outcome was organ failure-free days to 14 days of enrollment. Secondary outcomes included other measures for organ failure, intensive care unit (ICU) admission, duration of ICU and hospital stays, incidence of infected pancreatic necrosis, and 60-day mortality. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) analyses were used to control potential confounders.

Results

Overall, 267 patients with HTG-AP were enrolled (185 [69.3%] were male; median [IQR] age, 37 [31-43] years), among whom 211 underwent conventional medical treatment and 56 underwent plasmapheresis. PSM created 47 pairs of patients with balanced baseline characteristics. In the matched cohort, no difference was detected concerning organ failure-free days between patients undergoing plasmapheresis or not (median [IQR], 12.0 [8.0-14.0] vs 13.0 [8.0-14.0]; P = .94). Moreover, more patients in the plasmapheresis group required ICU admission (44 [93.6%] vs 24 [51.1%]; P < .001). The IPTW results conformed to the results from the PSM analysis.

Conclusions and Relevance

In this large multicenter cohort study of patients with HTG-AP, plasmapheresis was commonly used to lower plasma triglyceride. However, after adjusting for confounders, plasmapheresis was not associated with the incidence and duration of organ failure, but with increased ICU requirements.

[Oxygen therapy in intensive care]

PULSE OXIMETRY AND BLOOD GAS ANALYSES

Pulse oximetry has high sensitivity but low specificity for detecting hypoxemia. Arterial blood gas analyses are the gold standard for monitoring O2 therapy. Venous blood gas analyses should not be used in this setting. TARGET VALUES OF O2 THERAPY: The target range of acute O2 therapy for ventilated patients and nonventilated patients not at risk of hypercapnia should be between 92% and 96% for oxygen saturation (SpO2) measured by pulse oximetry. Indications for high-dose O2 therapy without a target range in critical care include carbon monoxide poisoning and patients with severe respiratory distress when SpO2 cannot be derived. Hyperoxemia, i.e., SpO2 values above 96%, has not improved survival in randomized trials of predominantly ventilated ICU patients. Under hyperoxemia in nonventilated patients at risk of hypercapnia (e.g., patients with chronic obstructive pulmonary disease), one in three patients is at risk of increasing carbon dioxide. Therefore, a target SpO2 of 88-92% should be aimed for in these patients. O2 TARGET RANGES ON EXTRACORPOREAL PROCEDURES: There are no randomized studies recommending other SpO2 target ranges for patients on extracorporeal procedures. These patients should always be monitored with arterial blood gases-in the case of peripheral VA-ECMO on the right arm and downstream of the oxygenator. HIGH-FLOW OXYGEN THERAPY FOR ACUTE HYPERCAPNIC RESPIRATORY FAILURE: High-flow oxygen therapy (HFNC) was not associated with reduced in-hospital mortality compared with conventional O2 in a meta-analysis of predominantly patients with acute hypoxemia (type I respiratory failure), although intubation rates were reduced. Also, in acute hypercapnic respiratory failure (type II), HFNC with high flow rates is not inferior to noninvasive ventilation (NIV).

Oxygenation target in acute respiratory distress syndrome

Determining oxygenation targets in acute respiratory distress syndrome (ARDS) remains a challenge. Although oxygenation targets have been used since ARDS was first described, they have not been investigated in detail. However, recent retrospective and prospective trials have evaluated the optimal oxygenation threshold in patients admitted to the general intensive care unit. In view of the lack of prospective data, clinicians continue to rely on data from the few available trials to identify the optimal oxygenation strategy. Assessment of the cost-benefit ratio of the fraction of inspired oxygen (FiO₂) to the partial pressure of oxygen in the arterial blood (PaO₂) is an additional challenge. A high FiO₂ has been found to be responsible for respiratory failure and deaths in numerous animal models. Low and high PaO₂ values have also been demonstrated to be potential risk factors in experimental and clinical situations. The findings from this literature review suggest that PaO₂ values ranging between 80 mmHg and 90 mmHg are acceptable in patients with ARDS. The costs of rescue maneuvers needed to reach these targets have been discussed. Several recent papers have highlighted the risk of disagreement between arterial oxygen saturation (SaO₂) and peripheral oxygen saturation (SpO₂) values. In order to avoid discrepancies and hidden hypoxemia, SpO₂ readings need to be compared with those of SaO₂. Higher SpO₂ values may be needed to achieve the recommended PaO₂ and SaO₂ values.

Oxygen saturation targets for adults with acute hypoxemia in low and lower-middle income countries: a scoping review with analysis of contextual factors

Knowing the target oxygen saturation (SpO2) range that results in the best outcomes for acutely hypoxemic adults is important for clinical care, training, and research in low-income and lower-middle income countries (collectively LMICs). The evidence we have for SpO2 targets emanates from high-income countries (HICs), and therefore may miss important contextual factors for LMIC settings. Furthermore, the evidence from HICs is mixed, amplifying the importance of specific circumstances. For this literature review and analysis, we considered SpO2 targets used in previous trials, international and national society guidelines, and direct trial evidence comparing outcomes using different SpO2 ranges (all from HICs). We also considered contextual factors, including emerging data on pulse oximetry performance in different skin pigmentation ranges, the risk of depleting oxygen resources in LMIC settings, the lack of access to arterial blood gases that necessitates consideration of the subpopulation of hypoxemic patients who are also hypercapnic, and the impact of altitude on median SpO2 values. This process of integrating prior study protocols, society guidelines, available evidence, and contextual factors is potentially useful for the development of other clinical guidelines for LMIC settings. We suggest that a goal SpO2 range of 90-94% is reasonable, using high-performing pulse oximeters. Answering context-specific research questions, such as an optimal SpO2 target range in LMIC contexts, is critical for advancing equity in clinical outcomes globally.

Guideline-based management of acute respiratory failure and acute respiratory distress syndrome

Acute respiratory failure (ARF) is defined by acute and progressive hypoxemia caused by various cardiorespiratory or systemic diseases in previously healthy patients. Among ARF, acute respiratory distress syndrome (ARDS) is a serious condition with bilateral lung infiltration, which develops secondary to a variety of underlying conditions, diseases, or injuries. This review summarizes the current standard of care for ARF and ARDS based on current major guidelines in this field. When administering fluid in patients with ARF, particularly ARDS, restrictive strategies need to be considered in patients without shock or multiple organ dysfunction. Regarding oxygenation targets, avoiding excessive hyperoxemia and hypoxemia is probably a reasonable choice. As a result of the rapid spread and accumulation of evidence for high-flow nasal cannula oxygenation, it is now weakly recommended for the respiratory management of ARF in general and even for initial management of ARDS. Noninvasive positive pressure ventilation is also weakly recommended for the management of certain ARF conditions and as initial management of ARDS. Low tidal volume ventilation is now weakly recommended for all patients with ARF and strongly recommended for patients with ARDS. Limiting plateau pressure and high-level PEEP are weakly recommended for moderate-to-severe ARDS. Prone position ventilation with prolonged hours is weakly to strongly recommended for moderate-to-severe ARDS. In patients with COVID-19, ventilatory management is essentially the same as for ARF and ARDS, but awake prone positioning may be considered. In addition to standard care, treatment optimization and individualization, as well as the introduction of exploratory treatment, should be considered as appropriate. As a single pathogen, such as SARS-CoV-2, exhibits a wide variety of pathologies and lung dysfunction, ventilatory management for ARF and ARDS may be better tailored according to the respiratory physiologic status of individual patients rather than the causal or underlying diseases and conditions.

Hyperoxemia after reperfusion in cardiac arrest patients: a potential dose-response association with 30-day survival

BACKGROUND

Hyperoxemia may aggravate reperfusion brain injury after cardiac arrest. The aim of this study was to study the associations between different levels of hyperoxemia in the reperfusion period after cardiac arrest and 30-day survival.

METHODS

Nationwide observational study using data from four compulsory Swedish registries. Adult in- and out-of-hospital cardiac arrest patients admitted to an ICU, requiring mechanical ventilation, between January 2010 and March 2021, were included. The partial oxygen pressure (PaO2) was collected in a standardized way at ICU admission (± one hour) according to the simplified acute physiology score 3 reflecting the time interval with oxygen treatment from return of spontaneous circulation to ICU admission. Subsequently, patients were divided into groups based on the registered PaO2 at ICU admission. Hyperoxemia was categorized into mild (13.4-20 kPa), moderate (20.1-30 kPa) severe (30.1-40 kPa) and extreme (> 40 kPa), and normoxemia as PaO2 8-13.3 kPa. Hypoxemia was defined as PaO2 < 8 kPa. Primary outcome was 30-day survival and relative risks (RR) were estimated by multivariable modified Poisson regression.

RESULTS

In total, 9735 patients were included of which 4344 (44.6%) were hyperoxemic at ICU admission. Among these, 2217 were classified as mild, 1091 as moderate, 507 as severe, and 529 as extreme hyperoxemia. Normoxemia was present in 4366 (44.8%) patients and 1025 (10.5%) had hypoxemia. Compared to the normoxemia group, the adjusted RR for 30-day survival in the whole hyperoxemia group was 0.87 (95% CI 0.82-0.91). The corresponding results for the different hyperoxemia subgroups were; mild 0.91 (95% CI 0.85-0.97), moderate 0.88 (95% CI 0.82-0.95), severe 0.79 (95% CI 0.7-0.89), and extreme 0.68 (95% CI 0.58-0.79). Adjusted 30-day survival for the hypoxemia compared to normoxemia group was 0.83 (95% CI 0.74-0.92). Similar associations were seen in both out-of-hospital and in-hospital cardiac arrests.

CONCLUSION

In this nationwide observational study comprising both in- and out-of-hospital cardiac arrest patients, hyperoxemia at ICU admission was associated with lower 30-day survival.

The rationale, design, and methods of a trial to evaluate the efficacy and safety of oxygen therapy in patients with intermediate-risk acute pulmonary embolism

BACKGROUND

In patients with intermediate-risk pulmonary embolism (PE), reversal of hypoxic vasoconstriction could constitute a target for treatment that protects the right ventricular (RV) function until endogenous fibrinolysis occurs. The Air vs oxygen for Intermediate-Risk pulmonary embolism (AIR) trial aims to assess the effect of oxygen therapy in patients with intermediate-risk acute PE who do not have hypoxemia at baseline.

METHODS AND ANALYSES

AIR is a prospective, multicenter, randomized, open-label, parallel-group, proof-of-concept trial. A total of 90 patients hospitalized with intermediate-risk PE and an oxygen saturation of 90% or higher at baseline will be randomized in a 1:1 fashion to receive supplemental oxygen or ambient air. The primary outcome is a RV/LV diameter ratio equal or less than 1.0 on echocardiography measured 48 hours after the start of treatment. Secondary efficacy outcomes are the numerical change in the ratio of the RV to the LV diameter measured 48 hours and 7 days after the start of treatment, with respect to the baseline ratio measured at randomization. Clinical adverse events will be also collected.

RESULTS

Enrollment started in July 2019 and is expected to proceed until 2022. Median age of the first 50 patients was 74 years (interquartile range, 61-81), and 50% were female.

CONCLUSIONS

This multicenter trial will provide information about the value of supplemental oxygen in patients with intermediate-risk acute PE who do not have hypoxemia at baseline. The results will contribute to research that may assist patients with intermediate-risk PE in the future.

THE ROLE OF OBESITY AND PLASMA ADIPOCYTOKINES IN IMMUNE DYSREGULATION IN SEPSIS PATIENTS

Introduction: The dysregulated immune response in sepsis is highly variable, ranging from hyperinflammation to immunoparalysis. Obesity is associated with the release of inflammatory mediators from adipose tissue, known as adipocytokines, causing a chronic inflammatory state. Perhaps counterintuitively, obesity is also associated with lower mortality in sepsis patients. We investigated the association between obesity, circulating adipocytokine concentrations, immune dysregulation, and outcome in sepsis patients. Methods In this secondary analysis of a prospective study, plasma concentrations of the adipocytokines leptin, adiponectin, and resistin were assessed in 167 patients at diagnosis of sepsis due to pneumonia, bacteremia, or acute cholangitis. Adipocytokines were compared between patients with normal weight (body mass index [BMI], 18.5-24.9 kg/m 2 ; n = 67), overweight (BMI, 25.0-29.9 kg/m 2 ; n = 56), and obesity (BMI ≥30 kg/m 2 ; n = 42), as well as between immunological endotypes: hyperinflammation (n = 40), immunoparalysis (n = 62), and unclassified (n = 55). Results: Higher circulating concentrations of leptin were observed in patients with obesity compared with patients with normal weight ( P = 0.008) and overweight ( P = 0.02), whereas adiponectin and resistin plasma concentrations were not different ( P = 0.08 and P = 0.85, respectively). Resistin concentrations were associated with immunological endotypes, with the highest levels found in hyperinflammatory patients ( P < 0.001). Furthermore, resistin concentrations were predictive for 28-day mortality (adjusted odds ratio, 1.03 per 10 ng/mL; P = 0.04). These associations were not found for leptin and adiponectin. Conclusion: Obesity and BMI-related adipocytokines are not related to the development of a hyperactive or suppressed immune response as defined by ferritin and mHLA-DR expression in sepsis patients. Although resistin is related to the immune response and an increased risk of adverse clinical outcomes, these associations are similar in patients with normal weight, overweight, and obesity. This implies that the relationship between resistin and clinical outcome is likely driven by the inflammatory response and not by obesity itself. Taken together, although there exists a strong association between inflammation and sepsis mortality, our results do not point toward a role for obesity and BMI-related adipocytokines in immune dysregulation in sepsis patients.

Therapeutic plasma exchange in patients with sepsis: Secondary analysis of a cluster-randomized controlled trial

INTRODUCTION

Sepsis is life-threatening organ dysfunction caused by infection-related inflammatory response. Therapeutic plasma exchange (TPE) can remove inflammatory mediators and benefit patients in different disease settings. However, no solid evidence showed the efficacy and safety of TPE in sepsis.

METHODS

This study was a secondary analysis of a randomized controlled trial. Critically ill patients with sepsis were divided into two groups according to whether treated with TPE. The primary outcome was the delta Sequential Organ Failure Assessment (SOFA) score from days 1 to 7. Secondary outcomes included new-onset organ failure, intensive care unit (ICU)-free and alive days to day 28, and 28-day mortality. Propensity score-matched (PSM) analysis was applied to control confounders. Analysis of covariance (ANCOVA) and logistic regression were used to assess the association between TPE and selected outcomes.

RESULTS

Among the 2772 critically ill patients enrolled in the trial, 742 patients with sepsis were selected and 22 patients received TPE were matched with 22 control patients. No significant difference was found in the delta SOFA score and 28-day mortality between TPE group and control group. The ICU-free and alive days in the TPE group were significantly shorter than the control group.

CONCLUSIONS

TPE may be not associated with improvement of organ failure and mortality in critically ill patients with sepsis and may be associated with a prolonged ICU stay.

Personalized medicine targeting different ARDS phenotypes: The future of pharmacotherapy for ARDS?

INTRODUCTION

Acute respiratory distress syndrome (ARDS) still represents a major challenge with high mortality rates and altered quality of life. Many well-designed studies have failed to improve ARDS outcomes. Heterogeneity of etiologies, mechanisms of lung damage, different lung mechanics, and different treatment approaches may explain these failures. At the era of personalized medicine, ARDS phenotyping is not only a field of research, but a bedside consideration when implementing therapy. ARDS has moved from being a simple syndrome to a more complex area of subgrouping. Intensivists must understand these phenotypes and therapies associated with a better outcome.

AREAS COVERED

After a brief sum-up of the different type of ARDS phenotypes, we will present some relevant therapy that may be impacted by phenotyping. A focus on pharmacotherapy will be realized before a section on non-pharmaceutical strategies. Eventually, we will highlight the limits of our knowledge of phenotyping and the pitfalls of personalized medicine.

EXPERT OPINION

Biological and morphological ARDS phenotypes are now well studied. The future of ARDS therapy will go through phenotyping that allows a personalized medication for each patient. However, a better assessment of these phenotypes is required, and clinical trials should be conducted with an ad-hoc phenotyping before randomization.

The danger of hyperoxia on the rat kidneys: is tadalafil a real shield?

PURPOSE

Continuous oxygen therapy to compensate for decreased oxygen saturation in the blood is a life-saving treatment used in case lung involvement. Excess oxygen delivery was reported to be a common situation, in which about 50% of the patients showed hyperoxemia and 4% in severe hyperoxemia. In this work, we investigated the effects of hyperoxia on the rat kidneys and whether tadalafil has an effect to reduce this damage.

MATERIALS AND METHODS

Three groups of 8 male rats each weighing 300-350 g were formed. The groups were divided into the control group, hyperoxia group, and hyperoxia and tadalafil administered group for 10 days. At the end of the 10th day, blood and kidney samples were taken for biochemical analysis (SOD and NO levels) and histopathological examination.

RESULTS

While our findings showed that SOD levels were significantly different among the control and experimental groups and within the experimental groups, no statistical difference was found in terms of NO levels among the groups (Table 1). While the glomerular and tubular injury was higher in the Hyperoxia group and the Hyperoxia + Tadalafil group than in the control group (p < 0.001), as a result of the rate of severe glomerular and tubular injury in the hyperoxia group, was 62.5% and 43.8% and in the group given tadalafil was 43.8% and 31.3%, respectively (Table 2).

CONCLUSIONS

Exposure to hyperoxia condition causes renal glomerular and tubular damage, and tadalafil does not show a protective effect on this damage according to this study's dose and exposure time.

Higher versus lower oxygenation strategies in the general intensive care unit population: A systematic review, meta-analysis and meta-regression of randomized controlled trials

PURPOSE

Oxygen therapy is vital in adult intensive care unit (ICU) patients, but it is indistinct whether higher or lower oxygen targets are favorable. Our aim was to update the findings of randomized controlled trials (RTCs) comparing higher and lower oxygen strategies.

MATERIALS AND METHODS

MEDLINE, EMBASE, and Web of Science were searched. RCTs comparing higher (liberal, hyperoxia) and lower (conservative, normoxia) oxygen in adult mechanically ventilated ICU patients were included. The main outcome was 90-day mortality; other outcomes include serious adverse events (SAE), support free days and length of stay (LOS).

RESULTS

No significant difference was observed for 90-day mortality. A lower incidence was found for SAEs, favoring lower oxygenation (OR, 0.86; 95%CI, 0.77-0.96; I ² 13%). No differences were observed in either support free days at day 28 or ICU and hospital LOS.

CONCLUSIONS

No difference was found for 90-day mortality, support free days and ICU and hospital LOS. However, a lower incidence of SAEs was found for lower oxygenation. These findings may have clinical implications for practice guidelines, yet it remains of paramount importance to continue conducting clinical trials, comparing groups with a clinically relevant contrast and focusing on the impact of important side effects.

Lower versus higher oxygenation targets in ICU patients with haematological malignancy - insights from the HOT-ICU trial

Background

Patients admitted to an intensive care unit (ICU) with active haematological malignancy and hypoxaemic respiratory failure have a high mortality. Oxygen supplementation is essential, but limited information exists on the optimum oxygenation targets in these patients.

Methods

This subgroup analysis was specified before completion of the Handling Oxygenation Targets in the ICU (HOT-ICU) trial. The trial investigated the effects of a lower (8 kPa) vs a higher (12 kPa) arterial oxygenation target and was stratified for active haematological malignancy, chronic obstructive pulmonary disease, and site. We here report the primary outcome (90-day mortality) and selected secondary outcomes in the subgroup of patients with active haematological malignancy.

Results

The HOT-ICU trial included 168 patients with active haematological malignancy; 82 were randomly allocated to an arterial oxygenation target of 8 kPa, and 86 to 12 kPa. At 90 days, 53/81 patients (65%) in the lower-oxygenation group and 47/86 patients (55%) in the higher-oxygenation group had died: adjusted relative risk 1.22 (95% confidence interval 0.95-1.56); at 1 year, the numbers were 58/81 (72%) vs 56/86 (65%): adjusted relative risk 1.11 (95% confidence interval 0.90-1.36). No statistically significant differences were found for any secondary outcomes.

Conclusion

In ICU patients with active haematological malignancies and hypoxaemic respiratory failure, we found a high mortality at 90 days and 1 year. Our results did not preclude clinically relevant benefits or harms of a lower oxygenation target in patients with active haematological malignancy. A randomised trial may, therefore, be worthwhile for these patients.

Clinical trial registration

NCT03174002.

High arterial oxygen levels and supplemental oxygen administration in traumatic brain injury: insights from CENTER-TBI and OzENTER-TBI

PURPOSE

The effect of high arterial oxygen levels and supplemental oxygen administration on outcomes in traumatic brain injury (TBI) is debated, and data from large cohorts of TBI patients are limited. We investigated whether exposure to high blood oxygen levels and high oxygen supplementation is independently associated with outcomes in TBI patients admitted to the intensive care unit (ICU) and undergoing mechanical ventilation.

METHODS

This is a secondary analysis of two multicenter, prospective, observational, cohort studies performed in Europe and Australia. In TBI patients admitted to ICU, we describe the arterial partial pressure of oxygen (PaO₂) and the oxygen inspired fraction (FiO₂). We explored the association between high PaO₂ and FiO₂ levels within the first week with clinical outcomes. Furthermore, in the CENTER-TBI cohort, we investigate whether PaO₂ and FiO₂ levels may have differential relationships with outcome in the presence of varying levels of brain injury severity (as quantified by levels of glial fibrillary acidic protein (GFAP) in blood samples obtained within 24 h of injury).

RESULTS

The analysis included 1084 patients (11,577 measurements) in the CENTER-TBI cohort, of whom 55% had an unfavorable outcome, and 26% died at a 6-month follow-up. Median PaO₂ ranged from 93 to 166 mmHg. Exposure to higher PaO₂ and FiO₂ in the first seven days after ICU admission was independently associated with a higher mortality rate. A trend of a higher mortality rate was partially confirmed in the OzENTER-TBI cohort (n = 159). GFAP was independently associated with mortality and functional neurologic outcome at follow-up, but it did not modulate the outcome impact of high PaO₂ levels, which remained independently associated with 6-month mortality.

CONCLUSIONS

In two large prospective multicenter cohorts of critically ill patients with TBI, levels of PaO₂ and FiO₂ varied widely across centers during the first seven days after ICU admission. Exposure to high arterial blood oxygen or high supplemental oxygen was independently associated with 6-month mortality in the CENTER-TBI cohort, and the severity of brain injury did not modulate this relationship. Due to the limited sample size, the findings were not wholly validated in the external OzENTER-TBI cohort. We cannot exclude the possibility that the worse outcomes associated with higher PaO₂ were due to use of higher FiO₂ in patients with more severe injury or physiological compromise. Further, these findings may not apply to patients in whom FiO₂ and PaO₂ are titrated to brain tissue oxygen monitoring (PbtO₂) levels. However, at minimum, these findings support the need for caution with oxygen therapy in TBI, particularly since titration of supplemental oxygen is immediately applicable at the bedside.

Oxygen-Saturation Targets for Critically Ill Adults Receiving Mechanical Ventilation

BACKGROUND

Invasive mechanical ventilation in critically ill adults involves adjusting the fraction of inspired oxygen to maintain arterial oxygen saturation. The oxygen-saturation target that will optimize clinical outcomes in this patient population remains unknown.

METHODS

In a pragmatic, cluster-randomized, cluster-crossover trial conducted in the emergency department and medical intensive care unit at an academic center, we assigned adults who were receiving mechanical ventilation to a lower target for oxygen saturation as measured by pulse oximetry (Spo₂) (90%; goal range, 88 to 92%), an intermediate target (94%; goal range, 92 to 96%), or a higher target (98%; goal range, 96 to 100%). The primary outcome was the number of days alive and free of mechanical ventilation (ventilator-free days) through day 28. The secondary outcome was death by day 28, with data censored at hospital discharge.

RESULTS

A total of 2541 patients were included in the primary analysis. The median number of ventilator-free days was 20 (interquartile range, 0 to 25) in the lower-target group, 21 (interquartile range, 0 to 25) in the intermediate-target group, and 21 (interquartile range, 0 to 26) in the higher-target group (P = 0.81). In-hospital death by day 28 occurred in 281 of the 808 patients (34.8%) in the lower-target group, 292 of the 859 patients (34.0%) in the intermediate-target group, and 290 of the 874 patients (33.2%) in the higher-target group. The incidences of cardiac arrest, arrhythmia, myocardial infarction, stroke, and pneumothorax were similar in the three groups.

CONCLUSIONS

Among critically ill adults receiving invasive mechanical ventilation, the number of ventilator-free days did not differ among groups in which a lower, intermediate, or higher Spo₂ target was used. (Supported by the National Heart, Lung, and Blood Institute and others; PILOT ClinicalTrials.gov number, NCT03537937.).

Automated closed–loop FiO2 titration increases the percentage of time spent in optimal zones of oxygen saturation in pediatric patients–A randomized crossover clinical trial

Introduction

We aimed to compare automated ventilation with closed–loop control of the fraction of inspired oxygen (FiO₂) to automated ventilation with manual titrations of the FiO₂ with respect to time spent in predefined pulse oximetry (SpO₂) zones in pediatric critically ill patients.

Methods

This was a randomized crossover clinical trial comparing Adaptive Support Ventilation (ASV) 1.1 with use of a closed–loop FiO₂ system vs. ASV 1.1 with manual FiO₂ titrations. The primary endpoint was the percentage of time spent in optimal SpO₂ zones. Secondary endpoints included the percentage of time spent in acceptable, suboptimal and unacceptable SpO₂ zones, and the total number of FiO₂ changes per patient.

Results

We included 30 children with a median age of 21 (11–48) months; 12 (40%) children had pediatric ARDS. The percentage of time spent in optimal SpO₂ zones increased with use of the closed–loop FiO₂ controller vs. manual oxygen control [96.1 (93.7–98.6) vs. 78.4 (51.3–94.8); P < 0.001]. The percentage of time spent in acceptable, suboptimal and unacceptable zones decreased. Findings were similar with the use of closed-loop FiO₂ controller compared to manual titration in patients with ARDS [95.9 (81.6–98.8) vs. 78 (49.5–94.8) %; P = 0.027]. The total number of closed-loop FiO₂ changes per patient was 52 (11.8–67), vs. the number of manual changes 1 (0–2), (P < 0.001).

Conclusion

In this randomized crossover trial in pediatric critically ill patients under invasive ventilation with ASV, use of a closed–loop control of FiO₂ titration increased the percentage of time spent within in optimal SpO₂ zones, and increased the total number of FiO₂ changes per patient.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT04568642.