Effect of Postextubation High-Flow Nasal Oxygen With Noninvasive Ventilation vs High-Flow Nasal Oxygen Alone on Reintubation Among Patients at High Risk of Extubation Failure: A Randomized Clinical Trial.

This article from the HIGH WEAN Study Group and REVA Research Network was published in JAMA during 2019.
Importance:  High-flow nasal oxygen may prevent postextubation respiratory failure in the intensive care unit (ICU). The combination of high-flow nasal oxygen with noninvasive ventilation (NIV) may be an optimal strategy of ventilation to avoid reintubation.
Objective:  To determine whether high-flow nasal oxygen with prophylactic NIV applied immediately after extubation could reduce the rate of reintubation, compared with high-flow nasal oxygen alone, in patients at high risk of extubation failure in the ICU.
Design, Setting, and Participants:  Multicenter randomized clinical trial conducted from April 2017 to January 2018 among 641 patients at high risk of extubation failure (ie, older than 65 years or with an underlying cardiac or respiratory disease) at 30 ICUs in France; follow-up was until April 2018.
Interventions: Patients were randomly assigned to high-flow nasal oxygen alone (n = 306) or high-flow nasal oxygen with NIV (n = 342) immediately after extubation.
Main Outcomes and Measures:  The primary outcome was the proportion of patients reintubated at day 7; secondary outcomes included postextubation respiratory failure at day 7, reintubation rates up until ICU discharge, and ICU mortality.
Results:  Among 648 patients who were randomized (mean [SD] age, 70 [10] years; 219 women [34%]), 641 patients completed the trial. The reintubation rate at day 7 was 11.8% (95% CI, 8.4%-15.2%) (40/339) with high-flow nasal oxygen and NIV and 18.2% (95% CI, 13.9%-22.6%) (55/302) with high-flow nasal oxygen alone (difference, -6.4% [95% CI, -12.0% to -0.9%]; P = .02). Among the 11 prespecified secondary outcomes, 6 showed no significant difference. The proportion of patients with postextubation respiratory failure at day 7 (21% vs 29%; difference, -8.7% [95% CI, -15.2% to -1.8%]; P = .01) and reintubation rates up until ICU discharge (12% vs 20%, difference -7.4% [95% CI, -13.2% to -1.8%]; P = .009) were significantly lower with high-flow nasal oxygen and NIV than with high-flow nasal oxygen alone. ICU mortality rates were not significantly different: 6% with high-flow nasal oxygen and NIV and 9% with high-flow nasal oxygen alone (difference, -2.4% [95% CI, -6.7% to 1.7%]; P = .25).
Conclusions and Relevance:  In mechanically ventilated patients at high risk of extubation failure, the use of high-flow nasal oxygen with NIV immediately after extubation significantly decreased the risk of reintubation compared with high-flow nasal oxygen alone.
The print copy of this issue JAMA is available in the Healthcare Library on D Level of Rotherham General Hospital.

Conservative Oxygen Therapy during Mechanical Ventilation in the ICU.

This publication from the ICU-ROX Investigators and the Australian and New Zealand Intensive Care Society Clinical Trials Group was published in the New England Journal of Medicine during 2019
Background:  Patients who are undergoing mechanical ventilation in the intensive care unit (ICU) often receive a high fraction of inspired oxygen (Fio2) and have a high arterial oxygen tension. The conservative use of oxygen may reduce oxygen exposure, diminish lung and systemic oxidative injury, and thereby increase the number of ventilator-free days (days alive and free from mechanical ventilation).
Methods:  We randomly assigned 1000 adult patients who were anticipated to require mechanical ventilation beyond the day after recruitment in the ICU to receive conservative or usual oxygen therapy. In the two groups, the default lower limit for oxygen saturation as measured by pulse oximetry (Spo2) was 90%. In the conservative-oxygen group, the upper limit of the Spo2 alarm was set to sound when the level reached 97%, and the Fio2 was decreased to 0.21 if the Spo2 was above the acceptable lower limit. In the usual-oxygen group, there were no specific measures limiting the Fio2 or the Spo2. The primary outcome was the number of ventilator-free days from randomization until day 28.
Results:  The number of ventilator-free days did not differ significantly between the conservative-oxygen group and the usual-oxygen group, with a median duration of 21.3 days (interquartile range, 0 to 26.3) and 22.1 days (interquartile range, 0 to 26.2), respectively, for an absolute difference of -0.3 days (95% confidence interval [CI], -2.1 to 1.6; P = 0.80). The conservative-oxygen group spent more time in the ICU with an Fio2 of 0.21 than the usual-oxygen group, with a median duration of 29 hours (interquartile range, 5 to 78) and 1 hour (interquartile range, 0 to 17), respectively (absolute difference, 28 hours; 95% CI, 22 to 34); the conservative-oxygen group spent less time with an Spo2 exceeding 96%, with a duration of 27 hours (interquartile range, 11 to 63.5) and 49 hours (interquartile range, 22 to 112), respectively (absolute difference, 22 hours; 95% CI, 14 to 30). At 180 days, mortality was 35.7% in the conservative-oxygen group and 34.5% in the usual-oxygen group, for an unadjusted odds ratio of 1.05 (95% CI, 0.81 to 1.37).
Conclusions:  In adults undergoing mechanical ventilation in the ICU, the use of conservative oxygen therapy, as compared with usual oxygen therapy, did not significantly affect the number of ventilator-free days.

The printed copy of the New England Journal of Medicine is available in the Health Care Library on D Level of Rotherham Hospital.

Effects of short-term hyperoxia on sytemic hemodynamics, oxygen transport, and microcirculation: An observational study in patients with septic shock and healthy volunteers

This research by Espinoza and others was published in Journal of Critical Care online in June 2019.
Purpose:  To characterize the microvascular effects of a brief period of hyperoxia, in patients with septic shock and in healthy volunteers.
Materials and methods:  In 20 patients with septic shock, we assessed systemic hemodynamics, sublingual microcirculation by SDF-videomicroscopy, and skin perfusion by capillary refill time (CRT), central-peripheral temperature (ΔT°), and perfusion index. Measurements were performed at baseline and after 5 min of inspired oxygen fraction of 1.00. Additionally, we studied 8 healthy volunteers, in whom hyperoxia was prolonged to 30 min.
Results:  In septic patients, hyperoxia increased mean arterial pressure and systemic vascular resistance, but cardiac output remained unchanged. The only significant change in sublingual microcirculation was a decreased heterogeneity flow index (1.03 [1.01–1.07] vs 1.01 [0.34–1.05], P = .002). Perfused vascular density (13.1 [12.0–15.0] vs 14.0 [12.2–14.8] mm/mm2, P = .21) and the other sublingual microvascular variables were unmodified. CRT and ΔT° did not change but perfusion index slightly decreased. In healthy volunteers, sublingual microcirculation and skin perfusion were stable.
Conclusions:  Short-term hyperoxia induced systemic cardiovascular changes but was not associated with noticeable derangement in sublingual microcirculation and skin perfusion. Nevertheless, longer exposures to hyperoxia might have produced different results.
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A mixed methods exploration of intensive care unit nurses’ perception of handling oxygen therapy to critically ill patients

This article was published on line in “Intensive and Critical Nursing” in January 2019 by Bunkenborg and Bundgaard.
Objectives:  Nurses handle supplementary oxygen to intensive care unit patients as part of their daily practise. To secure patients of optimal and safe care, knowledge of nurses’ perception of this practise, including influencing factors for adjusting oxygenation levels is essential. This study aimed to explore intensive care nurses’ perception of handling oxygenation and of factors that govern and influence this practise.
Research methodology/design:  A mixed methods approach was applied comprising six focus group interviews, conducted in February/March 2017, leading to construction of a questionnaire distributed to 535 ICU nurses in September 2017. Following a process of content analysis, the findings were discussed against Gittell’s framework for relational coordination.
Setting:  Intensive care units in rural, urban and university hospital settings.
Main outcome:  A deeper understanding of nurses’ perception of handling oxygenation to patients in the intensive care unit.
Findings and results:  Findings are presented through the categories Treatment Guidance, Nursing Practise, Knowledge and Competences and Inter-professional Collaboration.
Conclusion:  Nurses’ practise of handling supplementary oxygen therapy to the intensive care patient is influenced by day-by-day physician prescribed upper and lower limits for pO2 and pCO2, by nurses’ understanding of the individual clinical patient situation and by knowledge of pros and cons in relation to oxygen therapy including observational and clinical assessment expertise. Establishing working environments in the intensive care unit setting based on mutual inter- and intra-professional respect may contribute to enhance safe and high quality patient care.
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Intensive care doctors’ preferences for arterial oxygen tension levels in mechanically ventilated patients

This research by Schjørring and colleagues was published in Acta Anaesthesiologica Scandinavica in November 2018.
Background:  Oxygen is liberally administered in intensive care units (ICUs). Nevertheless, ICU doctors’ preferences for supplementing oxygen are inadequately described. The aim was to identify ICU doctors’ preferences for arterial oxygenation levels in mechanically ventilated adult ICU patients.
Methods:  In April to August 2016, an online multiple-choice 17-part-questionnaire was distributed to 1080 ICU doctors in seven Northern European countries. Repeated reminder e-mails were sent. The study ended in October 2016.
Results:  The response rate was 63%. When evaluating oxygenation 52% of respondents rated arterial oxygen tension (PaO2 ) the most important parameter; 24% a combination of PaO2 and arterial oxygen saturation (SaO2 ); and 23% preferred SaO2 . Increasing, decreasing or not changing a default fraction of inspired oxygen of 0.50 showed preferences for a PaO2 around 8 kPa in patients with chronic obstructive pulmonary disease, a PaO2 around 10 kPa in patients with healthy lungs, acute respiratory distress syndrome or sepsis, and a PaO2 around 12 kPa in patients with cardiac or cerebral ischaemia. Eighty per cent would accept a PaO2 of 8 kPa or lower and 77% would accept a PaO2 of 12 kPa or higher in a clinical trial of oxygenation targets.
Conclusion:  Intensive care unit doctors preferred PaO2 to SaO2 in monitoring oxygen treatment when peripheral oxygen saturation was not included in the question. The identification of PaO2 as the preferred target and the thorough clarification of preferences are important when ascertaining optimal oxygenation targets. In particular when designing future clinical trials of higher vs lower oxygenation targets in ICU patients.
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High-flow nasal cannula oxygen therapy alone or with non-invasive ventilation during the weaning period after extubation in ICU: the prospective randomised controlled HIGH-WEAN protocol

This article by Thille and colleagues as part of the REVA research network was published in BMJ Open in September 2018.
Introduction:  Recent practice guidelines suggest applying non-invasive ventilation (NIV) to prevent postextubation respiratory failure in patients at high risk of extubation failure in intensive care unit (ICU). However, such prophylactic NIV has been only a conditional recommendation given the low certainty of evidence. Likewise, high-flow nasal cannula (HFNC) oxygen therapy has been shown to reduce reintubation rates as compared with standard oxygen and to be as efficient as NIV in patients at high risk. Whereas HFNC may be considered as an optimal therapy during the postextubation period, HFNC associated with NIV could be an additional means of preventing postextubation respiratory failure. We are hypothesising that treatment associating NIV with HFNC between NIV sessions may be more effective than HFNC alone and may reduce the reintubation rate in patients at high risk.
Methods and Analysis:  This study is an investigator-initiated, multicentre randomised controlled trial comparing HFNC alone or with NIV sessions during the postextubation period in patients at high risk of extubation failure in the ICU. Six hundred patients will be randomised with a 1:1 ratio in two groups according to the strategy of oxygenation after extubation. The primary outcome is the reintubation rate within the 7 days following planned extubation. Secondary outcomes include the number of patients who meet the criteria for moderate/severe respiratory failure, ICU length of stay and mortality up to day 90.
Ethics and Dissemination: The study has been approved by the ethics committee and patients will be included after informed consent. The results will be submitted for publication in peer-reviewed journals.
The full text of this article is freely available via this link.

Intensive care doctors’ preferences for arterial oxygen tension levels in mechanically ventilated patients

This article by Schjorring and others was published in Acta Anaesthesioligica Scandinavica in June 2018.
Background:  Oxygen is liberally administered in intensive care units (ICUs). Nevertheless, ICU doctors’ preferences for supplementing oxygen are inadequately described. The aim was to identify ICU doctors’ preferences for arterial oxygenation levels in mechanically ventilated adult ICU patients.
Methods:  In April to August 2016, an online multiple-choice 17-part-questionnaire was distributed to 1080 ICU doctors in seven Northern European countries. Repeated reminder e-mails were sent. The study ended in October 2016.
Results:  The response rate was 63%. When evaluating oxygenation 52% of respondents rated arterial oxygen tension (PaO2 ) the most important parameter; 24% a combination of PaO2 and arterial oxygen saturation (SaO2 ); and 23% preferred SaO2 . Increasing, decreasing or not changing a default fraction of inspired oxygen of 0.50 showed preferences for a PaO2 around 8 kPa in patients with chronic obstructive pulmonary disease, a PaO2 around 10 kPa in patients with healthy lungs, acute respiratory distress syndrome or sepsis, and a PaO2 around 12 kPa in patients with cardiac or cerebral ischaemia. Eighty per cent would accept a PaO2 of 8 kPa or lower and 77% would accept a PaO2 of 12 kPa or higher in a clinical trial of oxygenation targets.
Conclusion:  Intensive care unit doctors preferred PaO2 to SaO2 in monitoring oxygen treatment when peripheral oxygen saturation was not included in the question. The identification of PaO2 as the preferred target and the thorough clarification of preferences are important when ascertaining optimal oxygenation targets. In particular when designing future clinical trials of higher vs lower oxygenation targets in ICU patients.
To access the full text of these articles via the journal’s homepage you require a personal subscription to the journal.  Some articles may be available freely without a password.  Library members can order individual articles via the Rotherham NHS Foundation Trust Library and Knowledge Service using the article requests online via this link.