Effects of oxygen therapy on wall-motion score index in patients with ST elevation myocardial infarction-the randomized SOCCER trial

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 We searched for ongoing or unpublished trials in clinical trial registers and scanned the reference lists and citations of included trials.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.

Supplemental Oxygen and Acute Myocardial Infarction ― A Systematic Review and Meta-Analysis ―

Background: In Japan, oxygen is commonly administered during the acute phase of myocardial infarction (MI) to patients without oxygen saturation monitoring. In this study we assessed the effects of supplemental oxygen therapy, compared with ambient air, on mortality and cardiac events by synthesizing evidence from randomized controlled trials (RCTs) of patients with suspected or confirmed acute MI.

Methods and Results: PubMed was systematically searched for full-text RCTs published in English before June 21, 2020. Two reviewers independently screened the search results and appraised the risk of bias. The estimates for each outcome were pooled using a random-effects model. In all, 2,086 studies retrieved from PubMed were screened. Finally, 7,322 patients from 9 studies derived from 4 RCTs were analyzed. In-hospital mortality in the oxygen and ambient air groups was 1.8% and 1.6%, respectively (risk ratio [RR] 0.90; 95% confidence interval [CI] 0.38–2.10]); 0.8% and 0.5% of patients, respectively, experienced recurrent MI (RR 0.44; 95% CI 0.12–1.54), 1.5% and 1.6% of patients, respectively, experienced cardiac shock (RR 1.10; 95% CI 0.77–1.59]), and 2.4% and 2.0% of patients, respectively, experienced cardiac arrest (RR 0.91; 95% CI 0.43–1.94).

Conclusions: Routine supplemental oxygen administration may not be beneficial or harmful, and high-flow oxygen may be unnecessary in normoxic patients in the acute phase of MI.

IDENTIFYING THE EFFECTS OF SUPPLEMENTAL OXYGEN ADMINISTRATION ON THE HEALTH OUTCOMES OF PATIENTS PRESENTING WITH ACUTE CORONARY SYNDROME AND OXYGEN SATURATION >93% - A SYSTEMATIC REVIEW

OBJECTIVES

Oxygen was commonly used in the early management of patients presenting with Acute Coronary Syndrome (ACS) regardless of their oxygen saturation. Inappropriate administration of supplemental oxygen could potentially result in adverse patient health outcomes.

AIM

To identify the effects of supplemental oxygen administration on the health outcomes of patients presenting with ACS and oxygen saturations >93%.

METHOD

Systematic review. The CINAHL, PubMed, Cochrane and Medline databases were searched for relevant literature. Inclusion criteria included articles published from 2008-2019, adult participants, primary studies, and participants with uncomplicated ACS and have oxygen saturation >93%. Eligible studies were assessed for rigour using a critical appraisal tool.

RESULTS

Seven randomised controlled studies were included for analysis. Themes were also used to group the assessed endpoints. The three main outcomes analysed were: infarct size and cardiac function; adverse cardiac events; and mortality. Two of the seven studies found a statistically significant relationship between oxygen administration, infarct size, and adverse cardiac events. Conversely, five of the seven studies reported that supplemental oxygen did not have statistically significant benefit over room air.

CONCLUSION

This review identified that oxygen should not be administered to patients who present with ACS and have oxygen saturations >93%. This is due to the potential risk of adverse outcomes: increased infarct size, mortality, and adverse events.

IMPACT STATEMENT

Recent update of guidelines despite evidence opposing oxygen delivery in ACS means the education of nurses is imperative for safe practice.

Oxygen therapy in patients with ST elevation myocardial infarction based on the culprit vessel: results from the randomized controlled SOCCER trial

BACKGROUND

Oxygen (O₂) treatment has been a cornerstone in the treatment of patients with myocardial infarction. Recent studies, however, state that supplemental O₂ therapy may have no effect or harmful effects in these patients. The aim of this study was thus to evaluate the effect of O₂ therapy in patients with ST Elevation Myocardial Infarction (STEMI) based on the culprit vessel; Left Anterior Descending Artery (LAD) or Non-LAD.

METHODS

This was a two-center, investigator-initiated, single-blind, parallel-group, randomized controlled trial at the Skåne university hospital, Sweden. A simple computer-generated randomization was used. Patients were either randomized to standard care with O₂ therapy (10 l/min) or air until the end of the primary percutaneous coronary intervention. The patients underwent a Cardiac Magnetic Resonance Imaging (CMRI) days 2-6. The main outcome measures were Myocardium at Risk (MaR), Infarct Size (IS) and Myocardial Salvage Index (MSI) as measured by CMRI, and median high-sensitive troponin T (hs-cTnT).

RESULTS

A total of 229 patients were assessed for eligibility, and 160 of them were randomized to the oxygen or air arm. Because of primarily technical problems with the CMRI, 95 patients were included in the final analyses; 46 in the oxygen arm and 49 in the air arm. There were no significant differences between patients with LAD and Non-LAD as culprit vessel with regard to their allocation (oxygen or air) with regards to MSI, MaR, IS and hs-cTnT.

CONCLUSION

The results indicate that the location of the culprit vessel has probably no effect on the role of supplemental oxygen therapy in STEMI patients.

TRIAL REGISTRATION

Swedish Medical Products Agency (EudraCT No. 2011-001452-11) and ClinicalTrials.gov Identifier (NCT01423929).

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.

High time to omit oxygen therapy in ST elevation myocardial infarction

Supplemental oxygen (O₂) therapy in patients with chest pain has been a cornerstone in the treatment of suspected myocardial infarction (MI). Recent randomized controlled trials have, however, shown that supplemental O₂ therapy has no positive nor negative effects on cardiovascular functions, mortality, morbidity or pain in normoxic patients with suspected MI and foremost patients with ST Elevation Myocardial Infarction (STEMI). O₂ therapy in normoxic STEMI patients should therefore be omitted. More studies are needed in discussing hemodynamically unstable STEMI patients, as well as patients with non-STEMI, unstable angina and other emergency conditions.

Effects of supplemental oxygen therapy in patients with suspected acute myocardial infarction: a meta-analysis of randomised clinical trials

Background

Although oxygen therapy has been used for over a century in the management of patients with suspected acute myocardial infarction (AMI), recent studies have raised concerns around the efficacy and safety of supplemental oxygen in normoxaemic patients.

Objective

To synthesise the evidence from randomised controlled trials (RCTs) that investigated the effects of supplemental oxygen therapy compared with room air in patients with suspected or confirmed AMI.

Methods

For this aggregate data meta-analysis, multiple databases were searched from inception to 30 September 2017. RCTs with any length of follow-up and any outcome measure were included if they studied the use of supplemental O2 therapy administered by any device at normal pressure compared with room air. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, an investigator assessed all the included studies and extracted the data. Outcomes of interests included mortality, troponin levels, infarct size, pain and hypoxaemia.

Results

Eight RCTs with a total of 7998 participants (3982 and 4002 patients in O2 and air groups, respectively) were identified and pooled. In-hospital and 30-day death occurred in 135 and 149 patients, respectively. Oxygen therapy did not reduce the risk of in-hospital (OR, 1.11 (95% CI 0.69 to 1.77)) or 30-day mortality (OR, 1.09 (95% CI 0.80 to 1.50)) in patients with suspected AMI, and the results remained similar in the subgroup of patients with confirmed AMI. The infarct size (based on cardiac MRI) in a subgroup of patients was not different between groups with and without O2 therapy. O2 therapy reduced the risk of hypoxaemia (OR, 0.29 (95% CI 0.17 to 0.47)).

Conclusion

Although supplemental O2 therapy is commonly used, it was not associated with important clinical benefits. These findings from eight RCTs support departing from the usual practice of administering oxygen in normoxaemic patients.

Effect of oxygen therapy on chest pain in patients with ST elevation myocardial infarction: results from the randomized SOCCER trial

OBJECTIVE

Oxygen (O₂) have been a cornerstone in the treatment of acute myocardial infarction. Studies have been inconclusive regarding the cardiovascular and analgesic effects of oxygen in these patients. In the SOCCER trial, we compared the effects of oxygen treatment versus room air in patients with ST-elevation myocardial infarction (STEMI). There was no difference in myocardial salvage index or infarct size assessed with cardiac magnetic resonance imaging. In the present subanalysis, we wanted to evaluate the effect of O₂ on chest pain in patients with STEMI.

DESIGN

Normoxic patients with first time STEMI were randomized in the ambulance to standard care with 10 l/min O₂ or room air until the end of the percutaneous coronary intervention (PCI). The ambulance personnel noted the patients´ chest pain on a visual analog scale (VAS; 1-10) before randomization and after the transport but before the start of the PCI, and also registered the amount of morphine given.

RESULTS

160 patients were randomized to O₂ (n = 85) or room air (n = 75). The O₂ group had a higher median VAS at randomization than the air group (7.0 ± 2.3 vs 6.0 ± 2.9; p = .02) and also received a higher median total dose of morphine (5.0 mg ± 4.4 vs 4.0 mg ± 3.7; p = .02). There was no difference between the O₂ and air groups in VAS at the start of the PCI (4.0 ± 2.4 vs 3.0 ± 2.5; p = .05) or in the median VAS decrease from randomization to the start of the PCI (-2.0 ± 2.2 vs -1.0 ± 2.9; p = .18).

CONCLUSION

Taken together with previously published data, these results do not support a significant analgesic effect of oxygen in patients with STEMI. European Clinical Trials Database (EudraCT): 2011-001452-11. ClinicalTrials.gov Identifier: NCT01423929.