What's new in oxygen therapy?

Association between SpO2 and the risk of death in elderly T2DM patients with cerebral infarction: a retrospective cohort study

Objective

This study aimed to evaluate the SpO2 (transcutaneous oxygen saturation) -mortality link in elderly T2DM (diabetes mellitus type 2) patients with cerebral infarction and identify their optimal SpO2 range.

Methods

In this investigation, we employed a comprehensive approach. Initially, we screened the MIMIC-IV database, identifying elderly T2DM patients with cerebral infarction, utilizing specific ICD-9 and ICD-10 codes. We then harnessed the power of restricted cubic splines to craft a visual representation of the correlation between SpO2 and 1-year mortality. To enhance our analysis, we harnessed Cox multivariate regression, allowing us to compute adjusted hazard ratios (HR) accompanied by 95% confidence intervals (CIs). Additionally, we crafted Cumulative Mortality Curve analyses, augmenting our study by engaging in rigorous subgroup analyses, stratifying our observations based on pertinent covariates.

Results

In this study, 448 elderly T2DM patients with cerebral infarction were included. Within 1-year post-discharge, 161 patients (35.94%) succumbed. Employing Restricted Cubic Spline analysis, a statistically significant U-shaped non-linear relationship between admission ICU SpO2 levels and 1-year mortality was observed (P-value < 0.05). Further analysis indicated that both low and high SpO2 levels increased the mortality risk. Cox multivariate regression analysis, adjusting for potential confounding factors, confirmed the association of low (≤94.5%) and high SpO2 levels (96.5-98.5%) with elevated 1-year mortality risk, particularly notably high SpO2 levels (>98.5%) [HR = 2.06, 95% CI: 1.29-3.29, P-value = 0.002]. The cumulative mortality curves revealed the following SpO2 subgroups from high to low cumulative mortality at the 365th day: normal levels (94.5% < SpO2 ≤ 96.5%), low levels (SpO2 ≤ 94.5%), high levels (96.5% < SpO2 ≤ 98.5%), and notably high levels (>98.5%). Subgroup analysis demonstrated no significant interaction between SpO2 and grouping variables, including Sex, Age, Congestive heart failure, Temperature, and ICU length of stay (LOS-ICU; P-values for interaction were >0.05).

Conclusions

Striking an optimal balance is paramount, as fixating solely on lower SpO2 limits or neglecting high SpO2 levels may contribute to increased mortality rates. To mitigate mortality risk in elderly T2DM patients with cerebral infarction, we recommend maintaining SpO2 levels within the range of 94.5-96.5%.

Hyperoxia in critically ill patients with sepsis and septic shock: a systematic review

BACKGROUND

In septic patients, hyperoxia may help with its bactericidal effects, but it may cause systemic impairments. The role of hyperoxia and the appropriate oxygen target in these patients is unknown. The aim of this systematic review was to summarize the available literature.

METHODS

We conducted a systematic search screening PubMed and Cochrane Library. Studies on adult patients with sepsis or septic shock and admitted to ICU addressing the topic of hyperoxia were included and described.

RESULTS

We included 12 studies, for a total of 15.782 included patients. Five studies were randomized controlled trials (RCTs) or analyses from RCTs, three were prospective observational studies, and four were retrospective observational studies. The definition of hyperoxia was heterogeneous across the included studies. Mortality was the most frequent outcome: six studies showed an increased rate or risk of mortality with hyperoxia, three found no differences, and one a protective effect of hyperoxia. At the critical appraisal assessment stage, no major methodological flaws were detected, except for a single-center, pilot study, with a lack of adjustment for confounders and imbalance between the groups.

CONCLUSION

The optimum range of oxygen level able to minimize risks and provide benefits in patients with sepsis or septic shock seems still unknown. Clinical equipoise between hyperoxia and normoxia is uncertain as conflicting evidence exists. Further studies should aim at identifying the best range of oxygenation and its optimal duration, investigating how effects of different levels of oxygen may vary according to identified pathogens, source of infection, and prescribed antibiotics in critically ill patients with sepsis and septic shock.

A nomogram to predict prolonged stay of obesity patients with sepsis in ICU: Relevancy for predictive, personalized, preventive, and participatory healthcare strategies

Objective

In an era of increasingly expensive intensive care costs, it is essential to evaluate early whether the length of stay (LOS) in the intensive care unit (ICU) of obesity patients with sepsis will be prolonged. On the one hand, it can reduce costs; on the other hand, it can reduce nosocomial infection. Therefore, this study aimed to verify whether ICU prolonged LOS was significantly associated with poor prognosis poor in obesity patients with sepsis and develop a simple prediction model to personalize the risk of ICU prolonged LOS for obesity patients with sepsis.

Method

In total, 14,483 patients from the eICU Collaborative Research Database were randomized to the training set (3,606 patients) and validation set (1,600 patients). The potential predictors of ICU prolonged LOS among various factors were identified using logistic regression analysis. For internal and external validation, a nomogram was developed and performed.

Results

ICU prolonged LOS was defined as the third quartile of ICU LOS or more for all sepsis patients and demonstrated to be significantly associated with the mortality in ICU by logistic regression analysis. When entering the ICU, seven independent risk factors were identified: maximum white blood cell, minimum white blood cell, use of ventilation, Glasgow Coma Scale, minimum albumin, maximum respiratory rate, and minimum red blood cell distribution width. In the internal validation set, the area under the curve was 0.73, while in the external validation set, it was 0.78. The calibration curves showed that this model predicted probability due to actually observed probability. Furthermore, the decision curve analysis and clinical impact curve showed that the nomogram had a high clinical net benefit.

Conclusion

In obesity patients with sepsis, we created a novel nomogram to predict the risk of ICU prolonged LOS. This prediction model is accurate and reliable, and it can assist patients and clinicians in determining prognosis and making clinical decisions.

Hyperoxemia in postsurgical sepsis/septic shock patients is associated with reduced mortality

BACKGROUND

Despite growing interest in treatment strategies that limit oxygen exposure in ICU patients, no studies have compared conservative oxygen with standard oxygen in postsurgical patients with sepsis/septic shock, although there are indications that it may improve outcomes. It has been proven that high partial pressure of oxygen in arterial blood (PaO2) reduces the rate of surgical-wound infections and mortality in patients under major surgery. The aim of this study is to examine whether PaO2 is associated with risk of death in adult patients with sepsis/septic shock after major surgery.

METHODS

We performed a secondary analysis of a prospective observational study in 454 patients who underwent major surgery admitted into a single ICU. Patients were stratified in two groups whether they had hyperoxemia, defined as PaO2 > 100 mmHg (n = 216), or PaO2 ≤ 100 mmHg (n = 238) at the day of sepsis/septic shock onset according to SEPSIS-3 criteria maintained during 48 h. Primary end-point was 90-day mortality after diagnosis of sepsis. Secondary endpoints were ICU length of stay and time to extubation.

RESULTS

In patients with PaO2 ≤ 100 mmHg, we found prolonged mechanical ventilation (2 [8] vs. 1 [4] days, p < 0.001), higher ICU stay (8 [13] vs. 5 [9] days, p < 0.001), higher organ dysfunction as assessed by SOFA score (9 [3] vs. 7 [5], p < 0.001), higher prevalence of septic shock (200/238, 84.0% vs 145/216) 67.1%, p < 0.001), and higher 90-day mortality (37.0% [88] vs. 25.5% [55], p = 0.008). Hyperoxemia was associated with higher probability of 90-day survival in a multivariate analysis (OR 0.61, 95%CI: 0.39-0.95, p = 0.029), independent of age, chronic renal failure, procalcitonin levels, and APACHE II score > 19. These findings were confirmed when patients with severe hypoxemia at the time of study inclusion were excluded.

CONCLUSIONS

Oxygenation with a PaO2 above 100 mmHg was independently associated with lower 90-day mortality, shorter ICU stay and intubation time in critically ill postsurgical sepsis/septic shock patients. Our findings open a new venue for designing clinical trials to evaluate the boundaries of PaO2 in postsurgical patients with severe infections.

A high fraction of inspired oxygen may increase mortality in intubated trauma patients - A retrospective cohort study

BACKGROUND

Mechanical ventilation of trauma patients is common, and many will require a higher than normal fraction of inspired oxygen (FiO₂) to avoid hypoxaemia. The primary objective of this study was to assess the association between FiO₂ and all-cause, one-year mortality in intubated trauma patients.

METHODS

Adult trauma patients intubated in the initial phase post-trauma between 2015 and 2017 were retrospectively identified. Information on FiO₂ during the first 24 hours of hospitalisation and mortality was registered. For each patient the number of hours of the first 24 hours exposed to an FiO₂ ≥ 80%, ≥ 60%, and ≥ 40%, respectively, were determined and categorised into exposure durations. The associations of these FiO₂ exposures with mortality were evaluated using Cox regression adjusting for age, sex, body mass index (BMI), Injury Severity Score (ISS), prehospital Glasgow Coma Scale (GCS) score, and presence of thoracic injuries.

RESULTS

We included 218 intubated trauma patients. The median prehospital GCS score was 6 and the median ISS was 25. One-year mortality was significantly increased when patients had received an FiO₂ above 80% for 3-4 hours compared to <2 hours (hazard ratio (95% CI) 2.7 (1.3-6.0), p= 0.011). When an FiO₂ above 80% had been administered for more than 4 hours, there was a trend towards a higher mortality as well, but this was not statistically significant. There was a significant, time-dependent increase in mortality for patients who had received an FiO₂ ≥ 60%. There was no significant relationship observed between mortality and the duration of FiO₂ ≥ 40%.

CONCLUSION

A fraction of inspired oxygen above 60% for more than 2 hours during the first 24 hours of admission was associated with increased mortality in intubated trauma patients in a duration-dependent manner. However, given the limitations of this retrospective study, the findings need to be confirmed in a larger, randomized set-up.

Long-term mortality and health-related quality of life of lower versus higher oxygenation targets in ICU patients with severe hypoxaemia

PURPOSE

We assessed outcomes after 1 year of lower versus higher oxygenation targets in intensive care unit (ICU) patients with severe hypoxaemia.

METHODS

Pre-planned analyses evaluating 1-year mortality and health-related quality-of-life (HRQoL) outcomes in the previously published Handling Oxygenation Targets in the ICU trial which randomised 2928 adults with acute hypoxaemia to targets of arterial oxygen of 8 kPa or 12 kPa throughout the ICU stay up to 90 days. One-year all-cause mortality was assessed in the intention-to-treat population. HRQoL was assessed using EuroQol 5 dimensions 5 levels (EQ-5D-5L) questionnaire and EQ visual analogue scale score (EQ-VAS), and analyses were conducted in both survivors only and the intention-to-treat population with assignment of the worst scores to deceased patients.

RESULTS

We obtained 1-year vital status for 2887/2928 (98.6%), and HRQoL for 2600/2928 (88.8%) of the trial population. One year after randomisation, 707/1442 patients (49%) in the lower oxygenation group vs. 704/1445 (48.7%) in the higher oxygenation group had died (adjusted risk ratio 1.00; 95% confidence interval 0.93-1.08, p = 0.92). In total, 1189/1476 (80.4%) 1-year survivors participated in HRQoL interviews: median EQ-VAS scores were 65 (interquartile range 50-80) in the lower oxygenation group versus 67 (50-80) in the higher oxygenation group (p = 0.98). None of the five EQ-5D-5L dimensions differed between groups.

CONCLUSION

Among adult ICU patients with severe hypoxaemia, a lower oxygenation target (8 kPa) did not improve survival or HRQoL at 1 year as compared to a higher oxygenation target (12 kPa).

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.

Conservative oxygen therapy for mechanically ventilated adults with suspected hypoxic ischaemic encephalopathy

PURPOSE

Liberal use of oxygen may contribute to secondary brain injury in patients with hypoxic-ischaemic encephalopathy (HIE). However, there are limited data on the effect of different oxygen regimens on survival and neurological disability in HIE patients.

METHODS

We undertook a post-hoc analysis of the 166 patients with suspected HIE enrolled in a trial comparing conservative oxygen therapy with usual oxygen therapy in 1000 mechanically ventilated ICU patients. The primary endpoint for the current analysis was death or unfavourable neurological outcome at day 180. Key secondary outcomes were day 180 mortality, and cause-specific mortality.

RESULTS

Patients with HIE allocated to conservative oxygen spent less time in the ICU with an SpO₂ ≥ 97% (26 h [interquartile range (IQR) 13-45 vs. 35 h [IQR 19-70], absolute difference, 9 h; 95% CI - 21.4 to 3.4). A total of 43 of 78 patients (55.1%) assigned to conservative oxygen and 49 of 72 patients (68.1%) assigned to usual oxygen died or had an unfavourable neurological outcome at day 180; odds ratio 0.58; 95% CI 0.3-1.12; P = 0.1 adjusted odds ratio 0.54; 95% CI 0.23-1.26; P = 0.15. A total of 37 of 86 patients (43%) assigned to conservative oxygen and 46 of 78 (59%) assigned to usual oxygen had died by day 180; odds ratio 0.53; 95% CI 0.28-0.98; P = 0.04; adjusted odds ratio 0.56; 95% CI 0.25-1.23; P = 0.15. Cause-specific mortality was similar by treatment group.

CONCLUSIONS

Conservative oxygen therapy was not associated with a statistically significant reduction in death or unfavourable neurological outcomes at day 180. The potential for important benefit or harm from conservative oxygen therapy in HIE patients is not excluded by these data.

Advances in Normobaric Hyperoxia Brain Protection in Experimental Stroke

As we all know that stroke is still a leading cause of death and acquired disability. Etiological treatment and brain protection are equally important. This review aimed to summarize the advance of normobaric-hyperoxia (NBHO) on brain protection in the setting of experimental stroke and brain trauma. We analyzed the data from relevant studies published on PubMed Central (PMC) and EMBASE, about NBHO on brain protection in the setting of experimental ischemic and hemorrhagic strokes and brain trauma, which revealed that NBHO had important value on improving hypoxia and attenuating ischemia damage. The mechanisms of NBHO involved increasing the content of oxygen in brain tissues, restoring the function of mitochondria, enhancing the metabolism of neurons, alleviating blood-brain barrier (BBB) damage, weakening brain cell edema, reducing intracranial pressure, and improving cerebral blood flow, especially in the surrounding of injured area of the brain, to make the neurons in penumbral area alive. Compared to hyperbaric oxygen (HBO), NBHO is more safe and more easily to transform to clinical use, whereby, further studies about the safety and efficacy as well as the proper treatment protocol of NBHO on human may be still needed.

Conservative oxygen therapy for mechanically ventilated adults with sepsis: a post hoc analysis of data from the intensive care unit randomized trial comparing two approaches to oxygen therapy (ICU-ROX)

PURPOSE

Sepsis is a common reason for intensive care unit (ICU) admission and mortality in ICU patients. Despite increasing interest in treatment strategies limiting oxygen exposure in ICU patients, no trials have compared conservative vs. usual oxygen in patients with sepsis.

METHODS

We undertook a post hoc analysis of the 251 patients with sepsis enrolled in a trial that compared conservative oxygen therapy with usual oxygen therapy in 1000 mechanically ventilated ICU patients. The primary end point for the current analysis was 90-day mortality. Key secondary outcomes were cause-specific mortality, ICU and hospital length of stay, ventilator-free days, vasopressor-free days, and the proportion of patients receiving renal replacement therapy in the ICU.

RESULTS

Patients with sepsis allocated to conservative oxygen therapy spent less time in the ICU with an SpO₂ ≥ 97% (23.5 h [interquartile range (IQR) 8-70] vs. 47 h [IQR 11-93], absolute difference, 23 h; 95% CI 8-38), and more time receiving an FiO₂ of 0.21 than patients allocated to usual oxygen therapy (20.5 h [IQR 1-79] vs. 0 h [IQR 0-10], absolute difference, 20 h; 95% CI 14-26). At 90-days, 47 of 130 patients (36.2%) assigned to conservative oxygen and 35 of 120 patients (29.2%) assigned to usual oxygen had died (absolute difference, 7 percentage points; 95% CI - 4.6 to 18.6% points; P = 0.24; interaction P = 0.35 for sepsis vs. non-sepsis). There were no statistically significant differences between groups for secondary outcomes but point estimates of treatment effects consistently favored usual oxygen therapy.

CONCLUSIONS

Point estimates for the treatment effect of conservative oxygen therapy on 90-day mortality raise the possibility of clinically important harm with this intervention in patients with sepsis; however, our post hoc analysis was not powered to detect the effects suggested and our data do not exclude clinically important benefit or harm from conservative oxygen therapy in this patient group.

CLINICAL TRIALS REGISTRY

ICU-ROX Australian and New Zealand Clinical Trials Registry number ACTRN12615000957594.

Low versus high pulse oxygen saturation directed oxygen therapy in critically ill patients: a randomized controlled pilot study

Background

Data on the safety and feasibility of pulse oxygen saturation (SpO₂) directed oxygen therapy in mainland China are scarce. The aim of this pilot study was to test the feasibility of SpO₂ directed oxygen therapy and to calculate sample size base on differences in 28-day mortality rates for a large sample-sized randomized trial.

Methods

This prospective pilot study enrolled 214 adult patients with an expected intensive care unit (ICU) stay of more than 72 hours. Patients were randomized into a low SpO₂ group (SpO₂ 90-95%) or high SpO₂ group (SpO₂ 96-100%). The primary outcome was 28-day mortality.

Results

One hundred patients were included in the low SpO₂ group, and 114 patients were included in the high SpO₂ group. The demographic and baseline characteristics were not different. The time-weighted SpO₂ average was significantly lower in the low SpO₂ group than in the high SpO₂ group [mean ± standard deviation (SD), 95.7%±2.3% vs. 98.2%±1.8%, P<0.001]. Twenty-six patients (26%) in the low SpO₂ group died within 28 days after inclusion, while 37 patients (32.5%) in the high SpO₂ group died (P=0.301). The time to death within 28 days between the two groups was not different (P=0.284).

Conclusions

SpO₂ directed oxygen therapy in critically ill patients was feasible. Our pilot trial necessitates and rationalizes our large-sample multicenter trial.