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.

Lower vs Higher Oxygenation Target and Days Alive Without Life Support in COVID-19: The HOT-COVID Randomized Clinical Trial.

Importance: Supplemental oxygen is ubiquitously used in patients with COVID-19 and severe hypoxemia, but a lower dose may be beneficial. Objective: To assess the effects of targeting a Pao2 of 60 mm Hg vs 90 mm Hg in patients with COVID-19 and severe hypoxemia in the intensive care unit (ICU). Design, Setting, and Participants: Multicenter randomized clinical trial including 726 adults with COVID-19 receiving at least 10 L/min of oxygen or mechanical ventilation in 11 ICUs in Europe from August 2020 to March 2023. The trial was prematurely stopped prior to outcome assessment due to slow enrollment. End of 90-day follow-up was June 1, 2023. Interventions: Patients were randomized 1:1 to a Pao2 of 60 mm Hg (lower oxygenation group; n = 365) or 90 mm Hg (higher oxygenation group; n = 361) for up to 90 days in the ICU. Main Outcomes and Measures: The primary outcome was the number of days alive without life support (mechanical ventilation, circulatory support, or kidney replacement therapy) at 90 days. Secondary outcomes included mortality, proportion of patients with serious adverse events, and number of days alive and out of hospital, all at 90 days. Results: Of 726 randomized patients, primary outcome data were available for 697 (351 in the lower oxygenation group and 346 in the higher oxygenation group). Median age was 66 years, and 495 patients (68%) were male. At 90 days, the median number of days alive without life support was 80.0 days (IQR, 9.0-89.0 days) in the lower oxygenation group and 72.0 days (IQR, 2.0-88.0 days) in the higher oxygenation group (P = .009 by van Elteren test; supplemental bootstrapped adjusted mean difference, 5.8 days [95% CI, 0.2-11.5 days]; P = .04). Mortality at 90 days was 30.2% in the lower oxygenation group and 34.7% in the higher oxygenation group (risk ratio, 0.86 [98.6% CI, 0.66-1.13]; P = .18). There were no statistically significant differences in proportion of patients with serious adverse events or in number of days alive and out of hospital. Conclusion and Relevance: In adult ICU patients with COVID-19 and severe hypoxemia, targeting a Pao2 of 60 mm Hg resulted in more days alive without life support in 90 days than targeting a Pao2 of 90 mm Hg. Trial Registration: ClinicalTrials.gov Identifier: NCT04425031.

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."

Platform trials.

Platform trials focus on the perpetual testing of many interventions in a disease or a setting. These trials have lasting organizational, administrative, data, analytic, and operational frameworks making them highly efficient. The use of adaptation often increases the probabilities of allocating participants to better interventions and obtaining conclusive results. The COVID-19 pandemic showed the potential of platform trials as a fast and valid way to improved treatments. This review gives an overview of key concepts and elements using the Intensive Care Platform Trial (INCEPT) as an example.

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.

A survey of preferences for respiratory support in the intensive care unit for patients with acute hypoxaemic respiratory failure.

BACKGROUND: When caring for mechanically ventilated adults with acute hypoxaemic respiratory failure (AHRF), clinicians are faced with an uncertain choice between ventilator modes allowing for spontaneous breaths or ventilation fully controlled by the ventilator. The preferences of clinicians managing such patients, and what motivates their choice of ventilator mode, are largely unknown. To better understand how clinicians' preferences may impact the choice of ventilatory support for patients with AHRF, we issued a survey to an international network of intensive care unit (ICU) researchers. METHODS: We distributed an online survey with 32 broadly similar and interlinked questions on how clinicians prioritise spontaneous or controlled ventilation in invasively ventilated patients with AHRF of different severity, and which factors determine their choice. RESULTS: The survey was distributed to 1337 recipients in 12 countries. Of these, 415 (31%) completed the survey either fully (52%) or partially (48%). Most respondents were identified as medical specialists (87%) or physicians in training (11%). Modes allowing for spontaneous ventilation were considered preferable in mild AHRF, with controlled ventilation considered as progressively more important in moderate and severe AHRF. Among respondents there was strong support (90%) for a randomised clinical trial comparing spontaneous with controlled ventilation in patients with moderate AHRF. CONCLUSIONS: The responses from this international survey suggest that there is clinical equipoise for the preferred ventilator mode in patients with AHRF of moderate severity. We found strong support for a randomised trial comparing modes of ventilation in patients with moderate AHRF.

Pleural effusion and thoracentesis in ICU patients: A longitudinal observational cross-sectional study.

BACKGROUND: Pleural effusion is common among patients in the intensive care unit (ICU) but reported prevalence varies. Thoracentesis may improve respiratory status, however, indications for this are unclear. We aimed to explore prevalence, development, and progression of pleural effusion, and the incidence and effects of thoracentesis in adult ICU patients. METHODS: This is a prospective observational study utilizing repeated daily ultrasonographic assessments of pleurae bilaterally, conducted in all adult patients admitted to the four ICUs of a Danish university hospital throughout a 14-day period. The primary outcome was the proportion of patients with ultrasonographically significant pleural effusion (separation between parietal and visceral pleurae >20 mm) in either pleural cavity on any ICU day. Secondary outcomes included the proportion of patients with ultrasonographically significant pleural effusion receiving thoracentesis in ICU, and the progression of pleural effusion without drainage, among others. The protocol was published before study initiation. RESULTS: In total, 81 patients were included of which 25 (31%) had or developed ultrasonographically significant pleural effusion. Thoracentesis was performed in 10 of these 25 patients (40%). Patients with ultrasonographically significant pleural effusion, which was not drained, had an overall decrease in estimated pleural effusion volume on subsequent days. CONCLUSION: Pleural effusion was common in the ICU, but less than half of all patients with ultrasonographically significant pleural effusion underwent thoracentesis. Progression of pleural effusion without thoracentesis showed reduced volumes on subsequent days.

Patient-Important Outcomes Other Than Mortality in Contemporary ICU Trials: A Scoping Review.

OBJECTIVES: Randomized clinical trials (RCTs) conducted in adult ICU patients increasingly include patient-important outcomes other than mortality. This comes with challenges regarding outcome choices/definitions, handling of deceased patients and missing data in analyses, and choices of effect measures and statistical methods due to complex distributions. This scoping review aimed to characterize how these challenges are handled in relevant contemporary RCTs. DATA SOURCES: We systematically searched 10 selected journals for RCTs conducted primarily in adult ICU patients published between 1 January 2018 and 5 May 2022 reporting at least one patient-important outcome other than mortality, including "days alive without"…-type outcomes, functional/cognitive/neurologic outcomes, health-related quality of life (HRQoL) outcomes, and ordinal/other outcomes. STUDY SELECTION: Abstracts and full-texts were assessed independently and in duplicate by two reviewers. DATA EXTRACTION: Data were extracted independently and in duplicate by two reviewers using predefined and pilot-tested extraction forms and subsequently categorized to facilitate analysis. DATA SYNTHESIS: We included 687 outcomes from 167 RCTs, with 32% of RCTs using a patient-important outcome other than mortality as a (co-)primary outcome, most frequently "days alive without"…-type outcomes. Many different functional/cognitive/neurologic (103) and HRQoL (29) outcomes were reported. Handling of deceased patients varied, with analyses frequently restricted to survivors only for functional/cognitive/neurologic (62%) and HRQoL (89%) outcomes. Follow-up was generally longer and missing data proportions higher for functional/cognitive/neurologic and HRQoL outcomes. Most outcomes were analyzed using nonparametric tests (31%), linear regression/ t tests (27%), chi-square-like tests (12%), and proportional odds logistic regression (9%), often without presentation of actual treatment effects estimates (38%). CONCLUSIONS: In this sample of RCTs, substantial variation in practice and suboptimal methodological choices were observed. This calls for increased focus on standardizing outcome choices and definitions, adequate handling of missing data and deceased patients in analyses, and use of statistical methods quantifying effect sizes.

Senicapoc treatment in COVID-19 patients with severe respiratory insufficiency-A randomized, open-label, phase II trial.

BACKGROUND: The aim of the current study was to determine if treatment with senicapoc, improves the PaO2 /FiO2 ratio in patients with COVID-19 and severe respiratory insufficiency. METHODS: Investigator-initiated, randomized, open-label, phase II trial in four intensive care units (ICU) in Denmark. We included patients aged ≥18 years and admitted to an ICU with severe respiratory insufficiency due to COVID-19. The intervention consisted of 50 mg enteral senicapoc administered as soon as possible after randomization and again after 24 h. Patients in the control group received standard care only. The primary outcome was the PaO2 /FiO2 ratio at 72 h. RESULTS: Twenty patients were randomized to senicapoc and 26 patients to standard care. Important differences existed in patient characteristics at baseline, including more patients being on non-invasive/invasive ventilation in the control group (54% vs. 35%). The median senicapoc concentration at 72 h was 62.1 ng/ml (IQR 46.7-71.2). The primary outcome, PaO2 /FiO2 ratio at 72 h, was significantly lower in the senicapoc group (mean 19.5 kPa, SD 6.6) than in the control group (mean 24.4 kPa, SD 9.2) (mean difference -5.1 kPa [95% CI -10.2, -0.04] p = .05). The 28-day mortality in the senicapoc group was 2/20 (10%) compared with 6/26 (23%) in the control group (OR 0.36 95% CI 0.06-2.07, p = .26). CONCLUSIONS: Treatment with senicapoc resulted in a significantly lower PaO2 /FiO2 ratio at 72 h with no differences for other outcomes.

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.

Interactions in clinical trials: Protocol and statistical analysis plan for an explorative study of four randomized ICU trials on use of pantoprazole, oxygenation targets, haloperidol and intravenous fluids.

BACKGROUND: Intensive care unit (ICU) patients receive numerous interventions, but knowledge about potential interactions between these interventions is limited. Co-enrolment in randomized clinical trials represents a unique opportunity to investigate any such interactions. We aim to assess interactions in four randomized clinical trials with overlap in inclusion periods and patient populations. METHODS: This protocol and statistical analysis plan describes a secondary explorative analysis of interactions in four international ICU trials on pantoprazole, oxygenations targets, haloperidol and intravenous fluids, respectively. The primary outcome will be 90-day all-cause mortality. The secondary outcome will be days alive and out of hospital in 90 days after randomization. All patients included in the intention-to-treat populations of the four trials will be included. Four co-primary analyses will be conducted, one with each of the included trials as reference using a logistic regression model adjusted for the reference trial's stratification variables and for the co-interventions with interactions terms. The primary analytical measure of interest will be the analyses' tests of interaction. A p-value below .05 will be considered statically significant. The stratification variable- and co-intervention-adjusted effect estimates will be reported with 95% confidence intervals without adjustments for multiplicity. CONCLUSION: This exploratory analysis will investigate the presence of any interactions between pantoprazole, oxygenation targets, haloperidol and amount of intravenous fluids in four international ICU trials using co-enrolment. Assessment of possible interactions represents valuable information to guide the design, statistical powering and conduct of future trials.

Oxygenation targets in ICU patients with COVID-19: A post hoc subgroup analysis of the HOT-ICU trial.

BACKGROUND: Supplemental oxygen is the key intervention for severe and critical COVID-19 patients. With the unstable supplies of oxygen in many countries, it is important to define the lowest safe dosage. METHODS: In spring 2020, 110 COVID-19 patients were enrolled as part of the Handling Oxygenation Targets in the ICU trial (HOT-ICU). Patients were allocated within 12 h of ICU admission. Oxygen therapy was titrated to a partial pressure of arterial oxygen (PaO2 ) of 8 kPa (lower oxygenation group) or a PaO2 of 12 kPa (higher oxygenation group) during ICU stay up to 90 days. We report key outcomes at 90 days for the subgroup of COVID-19 patients. RESULTS: At 90 days, 22 of 54 patients (40.7%) in the lower oxygenation group and 23 of 55 patients (41.8%) in the higher oxygenation group had died (adjusted risk ratio: 0.87; 95% confidence interval, 0.58-1.32). The percentage of days alive without life support was significantly higher in the lower oxygenation group (p = 0.03). The numbers of severe ischemic events were low with no difference between the two groups. Proning and inhaled vasodilators were used more frequently, and the positive end-expiratory pressure was higher in the higher oxygenation group. Tests for interactions with the results of the remaining HOT-ICU population were insignificant. CONCLUSIONS: Targeting a PaO2 of 8 kPa may be beneficial in ICU patients with COVID-19. These results come with uncertainty due to the low number of patients in this unplanned subgroup analysis, and insignificant tests for interaction with the main HOT-ICU trial. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov number, NCT03174002. Date of registration: June 2, 2017.

Long-term cognitive and pulmonary functions following a lower versus a higher oxygenation target in the HOT-ICU trial: protocol and statistical analysis plan.

BACKGROUND: Although supplemental oxygen can be lifesaving, liberal oxygen administration causing hyperoxaemia may be harmful. The targets for oxygenation in patients with acute hypoxaemic respiratory failure acutely admitted to the intensive care unit (ICU) are strongly debated, and consensus on which targets to recommend has not been reached. The Handling Oxygenation Targets in the ICU (HOT-ICU) trial is a multicentre, randomised, parallel-group trial of a lower oxygenation target (arterial partial pressure of oxygen [PaO2 ] = 8 kPa) versus a higher oxygenation target (PaO2  = 12 kPa) in adult ICU patients with acute hypoxaemic respiratory failure. In this study, we aim to evaluate the effects of these targets on long-term cognitive and pulmonary function in Danish patients, enrolled in the HOT-ICU trial and surviving to 1-year follow-up. We hypothesise that a lower oxygenation target throughout the ICU stay may result in cognitive impairment, whereas a higher oxygenation target may result in impaired pulmonary function. METHODS: All patients enrolled in the HOT-ICU trial at Danish sites and surviving to 1 year after randomisation are eligible to participate. The last patient is expected to be included by November 2021. A Repeatable Battery for the Assessment of Neuropsychological Status and a body plethysmography, including diffusion capacity for carbon monoxide, both pre-planned secondary long-term outcomes of the HOT-ICU trial, will be obtained. CONCLUSION: This study will provide important information on the long-term effects of a lower versus a higher oxygenation target on cognitive and pulmonary function in adult ICU patients with acute hypoxaemic respiratory failure.

Lower versus higher oxygenation targets in critically ill patients with severe hypoxaemia: secondary Bayesian analysis to explore heterogeneous treatment effects in the Handling Oxygenation Targets in the Intensive Care Unit (HOT-ICU) trial.

BACKGROUND: In the Handling Oxygenation Targets in the Intensive Care Unit (HOT-ICU) trial, a lower (8 kPa) vs a higher (12 kPa) PaO2 target did not affect mortality amongst critically ill adult patients. We used Bayesian statistics to evaluate any heterogeneity in the effect of oxygenation targets on mortality between different patient groups within the HOT-ICU trial. METHODS: We analysed 90-day all-cause mortality using adjusted Bayesian logistic regression models, and assessed heterogeneous treatment effects according to four selected baseline variables using both hierarchical models of subgroups and models with interactions on the continuous scales. Results are presented as mortality probability (%) and relative risk (RR) with 95% credibility intervals (CrI). RESULTS: All 2888 patients in the intention-to-treat cohort of the HOT-ICU trial were included. The adjusted 90-day mortality rates were 43.0% (CrI: 38.3-47.8%) and 42.3% (CrI: 37.7-47.1%) in the lower and higher oxygenation groups, respectively (RR 1.02 [CrI: 0.93-1.11]), with 36.5% probability of an RR <1.00. Analyses of heterogeneous treatment effects suggested a dose-response relationship between baseline norepinephrine dose and increased mortality with the lower oxygenation target, with 95% probability of increased mortality associated with the lower oxygenation target as norepinephrine doses increased. CONCLUSIONS: A lower oxygenation target was unlikely to affect overall mortality amongst critically ill adult patients with acute hypoxaemic respiratory failure. However, our results suggest an increasing mortality risk for patients with a lower oxygen target as the baseline norepinephrine dose increases. These findings warrant additional investigation. CLINICAL TRIAL REGISTRATION: NCT03174002.

Lower or Higher Oxygenation Targets for Acute Hypoxemic Respiratory Failure.

BACKGROUND: Patients with acute hypoxemic respiratory failure in the intensive care unit (ICU) are treated with supplemental oxygen, but the benefits and harms of different oxygenation targets are unclear. We hypothesized that using a lower target for partial pressure of arterial oxygen (Pao2) would result in lower mortality than using a higher target. METHODS: In this multicenter trial, we randomly assigned 2928 adult patients who had recently been admitted to the ICU (≤12 hours before randomization) and who were receiving at least 10 liters of oxygen per minute in an open system or had a fraction of inspired oxygen of at least 0.50 in a closed system to receive oxygen therapy targeting a Pao2 of either 60 mm Hg (lower-oxygenation group) or 90 mm Hg (higher-oxygenation group) for a maximum of 90 days. The primary outcome was death within 90 days. RESULTS: At 90 days, 618 of 1441 patients (42.9%) in the lower-oxygenation group and 613 of 1447 patients (42.4%) in the higher-oxygenation group had died (adjusted risk ratio, 1.02; 95% confidence interval, 0.94 to 1.11; P = 0.64). At 90 days, there was no significant between-group difference in the percentage of days that patients were alive without life support or in the percentage of days they were alive after hospital discharge. The percentages of patients who had new episodes of shock, myocardial ischemia, ischemic stroke, or intestinal ischemia were similar in the two groups (P = 0.24). CONCLUSIONS: Among adult patients with acute hypoxemic respiratory failure in the ICU, a lower oxygenation target did not result in lower mortality than a higher target at 90 days. (Funded by the Innovation Fund Denmark and others; HOT-ICU ClinicalTrials.gov number, NCT03174002.).

Higher vs Lower Oxygenation Strategies in Acutely Ill Adults: A Systematic Review With Meta-Analysis and Trial Sequential Analysis.

BACKGROUND: Liberal oxygen supplementation is often used in acute illness but has, in some studies, been associated with harm. RESEARCH QUESTION: The goal of this study was to assess the benefits and harms of higher vs lower oxygenation strategies in acutely ill adults. STUDY DESIGN AND METHODS: This study was an updated systematic review with meta-analysis and Trial Sequential Analysis (TSA) of randomized clinical trials. A clear differentiation (separation) was made between a higher (liberal) oxygenation and a lower (conservative) oxygenation strategy and their effects on all-cause mortality, serious adverse events, quality of life, lung injury, sepsis, and cardiovascular events at time points closest to 90 days in acutely ill adults. RESULTS: The study included 50 randomized clinical trials of 21,014 participants; 36 trials with a total of 20,166 participants contributed data to the analyses. Meta-analysis and TSAs showed no difference between higher and lower oxygenation strategies in trials at overall low risk of bias except for blinding: mortality relative risk (RR), 0.98 (95% CI, 0.89-1.09; TSA-adjusted CI, 0.86-1.12; low certainty evidence); serious adverse events RR, 0.99 (95% CI, 0.89-1.12; TSA-adjusted CI, 0.83-1.19; low certainty evidence). The corresponding summary estimates including trials with overall low and high risk of bias showed similar results. No difference was found between higher and lower oxygenation strategies in meta-analyses and TSAs regarding quality of life, lung injury, sepsis, and cardiovascular events (very low certainty evidence). INTERPRETATION: No evidence was found of beneficial or harmful effects of higher vs lower oxygenation strategies in acutely ill adults (low to very low certainty evidence). CLINICAL TRIAL REGISTRATION: PROSPERO; No.: CRD42017058011; URL: https://www.crd.york.ac.uk/prospero/.

Arterial oxygen tensions in mechanically ventilated ICU patients and mortality: a retrospective, multicentre, observational cohort study.

BACKGROUND: Supplemental oxygen therapy is commonly required for respiratory failure requiring mechanical ventilation in the ICU. However, hyperoxaemia may be injurious and may increase mortality. We evaluated the relationship amongst the degree of hyperoxaemia and changes in fraction of inspired oxygen (Fio2) in response to hyperoxaemia, as well as associations with mortality in mechanically ventilated ICU patients. METHODS: We retrospectively identified all invasively mechanically ventilated patients admitted to five ICUs, and retrieved all oxygen tension (Pao2) and Fio2 data. We assessed the time between arterial blood gas (ABG) samples, proportions of patients with hyperoxaemia, and changes in Fio2 when hyperoxaemia was present. The primary outcome was the association between Pao2 (assessed by mechanically ventilated exposure-time-divided area under the curve [AUC]) and mortality (in-ICU and post-ICU discharge) using a multistate illness-death model with transition intensities estimated by Cox proportional hazards models. RESULTS: We assessed 177 769 ABG analyses obtained from 4998 patients between January 2012 and June 2016. The median time between ABGs was 3 h (inter-quartile range: 2-4 h); the median Pao2 was 11.3 kPa (9.8-13.6 kPa), and Fio2 was 0.40 (0.35-0.50). Hyperoxaemia (Pao2 >13.7 kPa) was present in 23.9% of the ABGs, and hyperoxaemia seemed to be disregarded when Fio2 was <0.40, as >50% of these Fio2 values were not subsequently reduced. AUC Pao2 >16.0 kPa was associated with increased ICU mortality (adjusted hazard ratio: 1.75; 95% confidence interval: 1.28-2.40). CONCLUSIONS: In mechanically ventilated ICU patients, hyperoxaemia was common. Although oxygen supplementation was often reduced when hyperoxaemia was observed, several patients remained hyperoxaemic. Hyperoxaemia was associated with increased ICU mortality in these patients.

Bayesian and heterogeneity of treatment effect analyses of the HOT-ICU trial-A secondary analysis protocol.

BACKGROUND: The Handling Oxygenation Targets in the Intensive Care Unit (HOT-ICU) trial is an ongoing randomised clinical trial exploring the benefits and harms of targeting a lower (8 kPa) versus a higher (12 kPa) arterial oxygenation target in adult patients acutely admitted to the intensive care unit (ICU) with hypoxaemic respiratory failure. METHODS: This protocol describes a secondary analysis of the primary trial outcome, 90-day all-cause mortality. We will analyse the primary outcome using Bayesian methods, which allows quantification of probabilities of all effect sizes. We will explore the presence of heterogeneity of treatment effects (HTE) using Bayesian hierarchical models in subgroups based on baseline parameters: (a) severity of illness (Sequential Organ Failure Assessment (SOFA) score), (b) severity of hypoxaemic respiratory failure (partial pressure of arterial oxygen (PaO2 )/fraction of inspired oxygen (FiO2 ) ratio), (c) vasopressor requirement (highest noradrenaline dose in the 24 hours prior to randomisation), and (d) plasma lactate concentration (latest prior to randomisation). Additionally, we will perform separate assessments of the treatment effect interaction with each of the baseline parameters above on the continuous scale and present these using conditional effects plots. CONCLUSIONS: This secondary analysis will aid the interpretation of the HOT-ICU trial by evaluating probabilities of all effect sizes. In addition, we will evaluate whether HTE is present, thus, further evaluating benefits and harms of a lower versus a higher oxygenation target in adult ICU patients with acute hypoxaemic respiratory failure.

The handling oxygenation targets in the intensive care unit (HOT-ICU) trial: Detailed statistical analysis plan.

BACKGROUND: No solid evidence exists on optimal oxygenation targets in intensive care patients. The handling oxygenation targets in the intensive care unit (HOT-ICU) trial assesses the effects of a targeted arterial oxygen tension of 8 vs 12 kPa on 90-day mortality in acutely admitted adult patients with hypoxaemic respiratory failure. This article describes the detailed statistical analysis plan for the predefined outcomes and supplementary analyses in the HOT-ICU trial. METHODS: The trial will include 2928 patients to be able to detect or reject a true 20% relative risk reduction in the primary outcome of 90-day all-cause mortality with an α of 5% and a ß of 10%. Analyses of the primary and secondary outcomes will be conducted according to the intention-to-treat principle and adjusted for stratification variables. The primary outcome and dichotomous secondary outcomes will be analysed using a generalised linear model with a log-link and binomial error distribution. For the primary outcome, a 95% confidence interval (CI) not including 1.00 for the risk ratio will be considered statistically significant. Continuous secondary outcomes will be analysed using a generalised linear model or nonparametric test. CIs adjusted for the multiple secondary outcomes not including the null effect will be considered statistically significant. One planned interim analysis has been conducted. CONCLUSIONS: The HOT-ICU trial and the pre-planned statistical analyses are designed to minimise bias and produce high quality data on the effects of a lower vs a higher oxygenation target throughout ICU admission in acutely admitted adult patients with hypoxaemic respiratory failure. REGISTRATION: ClinicalTrials.gov identifier: NCT03174002, date of registration: June 2, 2017. European clinical trials database, EudraCT number 2017-000632-34.

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

BACKGROUND: The mainstay treatment for hypoxaemia is oxygen therapy, which is given to the vast majority of adults admitted to the intensive care unit (ICU). The practice of oxygen administration has been liberal, which may result in hyperoxaemia. Some studies have indicated an association between hyperoxaemia and mortality, whilst other studies have not. The ideal target for supplemental oxygen for adults admitted to the ICU is uncertain. Despite a lack of robust evidence of effectiveness, oxygen administration is widely recommended in international clinical practice guidelines. The potential benefit of supplemental oxygen must be weighed against the potentially harmful effects of hyperoxaemia. OBJECTIVES: To assess the benefits and harms of higher versus lower fraction of inspired oxygen or targets of arterial oxygenation for adults admitted to the ICU. SEARCH METHODS: We identified trials through electronic searches of CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, BIOSIS Previews, CINAHL, and LILACS. We searched for ongoing or unpublished trials in clinical trials registers. We also scanned the reference lists of included studies. We ran the searches in December 2018. SELECTION CRITERIA: We included randomized controlled trials (RCTs) that compared higher versus lower fraction of inspired oxygen or targets of arterial oxygenation for adults admitted to the ICU. We included trials irrespective of publication type, publication status, and language. We included trials with a difference between the intervention and control groups of a minimum 1 kPa in partial pressure of arterial oxygen (PaO2), minimum 10% in fraction of inspired oxygen (FiO2), or minimum 2% in arterial oxygen saturation of haemoglobin/non-invasive peripheral oxygen saturation (SaO2/SpO2). We excluded trials randomizing participants to hypoxaemia (FiO2 below 0.21, SaO2/SpO2 below 80%, and PaO2 below 6 kPa) and to hyperbaric oxygen. DATA COLLECTION AND ANALYSIS: Three review authors independently, and in pairs, screened the references retrieved in the literature searches and extracted data. Our primary outcomes were all-cause mortality, the proportion of participants with one or more serious adverse events, and quality of life. None of the trials reported the proportion of participants with one or more serious adverse events according to the International Conference on Harmonisation Good Clinical Practice (ICH-GCP) criteria. Nonetheless, most trials reported several serious adverse events. We therefore included an analysis of the effect of higher versus lower fraction of inspired oxygen, or targets using the highest reported proportion of participants with a serious adverse event in each trial. Our secondary outcomes were lung injury, acute myocardial infarction, stroke, and sepsis. None of the trials reported on lung injury as a composite outcome, however some trials reported on acute respiratory distress syndrome (ARDS) and pneumonia. We included an analysis of the effect of higher versus lower fraction of inspired oxygen or targets using the highest reported proportion of participants with ARDS or pneumonia in each trial. To assess the risk of systematic errors, we evaluated the risk of bias of the included trials. We used GRADE to assess the overall certainty of the evidence. MAIN RESULTS: We included 10 RCTs (1458 participants), seven of which reported relevant outcomes for this review (1285 participants). All included trials had an overall high risk of bias, whilst two trials had a low risk of bias for all domains except blinding of participants and personnel. Meta-analysis indicated harm from higher fraction of inspired oxygen or targets as compared with lower fraction or targets of arterial oxygenation regarding mortality at the time point closest to three months (risk ratio (RR) 1.18, 95% confidence interval (CI) 1.01 to 1.37; I2 = 0%; 4 trials; 1135 participants; very low-certainty evidence). Meta-analysis indicated harm from higher fraction of inspired oxygen or targets as compared with lower fraction or targets of arterial oxygenation regarding serious adverse events at the time point closest to three months (estimated highest proportion of specific serious adverse events in each trial RR 1.13, 95% CI 1.04 to 1.23; I2 = 0%; 1234 participants; 6 trials; very low-certainty evidence). These findings should be interpreted with caution given that they are based on very low-certainty evidence. None of the included trials reported any data on quality of life at any time point. Meta-analysis indicated no evidence of a difference between higher fraction of inspired oxygen or targets as compared with lower fraction or targets of arterial oxygenation on lung injury at the time point closest to three months (estimated highest reported proportion of lung injury RR 1.03, 95% CI 0.78 to 1.36; I2 = 0%; 1167 participants; 5 trials; very low-certainty evidence). None of the included trials reported any data on acute myocardial infarction or stroke, and only one trial reported data on the effects on sepsis. AUTHORS' CONCLUSIONS: We are very uncertain about the effects of higher versus lower fraction of inspired oxygen or targets of arterial oxygenation for adults admitted to the ICU on all-cause mortality, serious adverse events, and lung injuries at the time point closest to three months due to very low-certainty evidence. Our results indicate that oxygen supplementation with higher versus lower fractions or oxygenation targets may increase mortality. None of the trials reported the proportion of participants with one or more serious adverse events according to the ICH-GCP criteria, however we found that the trials reported an increase in the number of serious adverse events with higher fractions or oxygenation targets. The effects on quality of life, acute myocardial infarction, stroke, and sepsis are unknown due to insufficient data.