BTS guideline for oxygen use in adults in healthcare and emergency settings

The effect of 50% oxygen on PtCO2 in patients with stable COPD, bronchiectasis, and neuromuscular disease or kyphoscoliosis: randomised cross-over trials

BACKGROUND

High-concentration oxygen therapy causes increased arterial partial pressure of carbon dioxide (PaCO2) in patients with COPD, asthma, pneumonia, obesity and acute lung injury. The objective of these studies was to investigate whether this physiological response to oxygen therapy occurs in stable patients with neuromuscular disease or kyphoscoliosis, and bronchiectasis.

METHODS

Three randomised cross-over trials recruited stable patients with neuromuscular disease or kyphoscoliosis (n = 20), bronchiectasis (n = 24), and COPD (n = 24). Participants were randomised to receive 50% oxygen and 21% oxygen (air), each for 30 min, in randomly assigned order. The primary outcome was transcutaneous partial pressure of carbon dioxide (PtCO2) at 30 min. The primary analysis was a mixed linear model.

RESULTS

Sixty six of the 68 participants had baseline PtCO2 values < 45 mmHg. The intervention baseline adjusted PtCO2 difference (95% CI) between oxygen and room air after 30 min was 0.2 mmHg (- 0.4 to 0.9), P = 0.40; 0.5 mmHg (- 0.2 to 1.2), P = 0.18; and 1.3 mmHg (0.7 to 1.8), P < 0.001, in the neuromuscular/kyphoscoliosis, bronchiectasis and COPD participants respectively.

CONCLUSIONS

The small increase in PtCO2 in the stable COPD patients with high-concentration oxygen therapy contrasts with the marked increases in PaCO2 seen in the setting of acute exacerbations of COPD. This suggests that the model of studying the effects of high-concentration oxygen therapy in patients with stable respiratory disease is not generalisable to the use of oxygen therapy in the acute clinical setting. Appropriate studies of high-concentration compared to titrated oxygen in acute clinical settings are needed to determine if there is a risk of oxygen-induced hypercapnia in patients with neuromuscular disease, kyphoscoliosis or bronchiectasis.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12615000970549 Registered 16/9/15, ACTRN12615000971538 Registered 16/9/15 and ACTRN12615001056583 Registered 7/10/15.

Systematic Review of Evidence-Based Guidelines for Prehospital Care

Introduction: Multiple national organizations have identified a need to incorporate more evidence-based medicine in emergency medical services (EMS) through the creation of evidence-based guidelines (EBGs). Tools like the Appraisal of Guidelines for Research and Evaluation (AGREE) II and criteria outlined by the National Academy of Medicine (NAM) have established concrete recommendations for the development of high-quality guidelines. While many guidelines have been created that address topics within EMS medicine, neither the quantity nor quality of prehospital EBGs have been previously reported. Objectives: To perform a systematic review to identify existing EBGs related to prehospital care and evaluate the quality of these guidelines using the AGREE II tool and criteria for clinical guidelines described by the NAM. Methods: We performed a systematic search of the literature in MEDLINE, EMBASE, PubMED, Trip, and guidelines.gov, through September 2018. Guideline topics were categorized based on the 2019 Core Content of EMS Medicine. Two independent reviewers screened titles for relevance and then abstracts for essential guideline features. Included guidelines were appraised with the AGREE II tool across 6 domains by 3 independent reviewers and scores averaged. Two additional reviewers determined if each guideline reported the key elements of clinical practice guidelines recommended by the NAM via consensus. Results: We identified 71 guidelines, of which 89% addressed clinical aspects of EMS medicine. Only 9 guidelines scored >75% across AGREE II domains and most (63%) scored between 50 and 75%. Domain 4 (Clarity of Presentation) had the highest (79.7%) and domain 5 (Applicability) had the lowest average score across EMS guidelines. Only 38% of EMS guidelines included a reporting of all criteria identified by the NAM for clinical practice guidelines, with elements of a systematic review of the literature most commonly missing. Conclusions: EBGs exist addressing a variety of topics in EMS medicine. This systematic review and appraisal of EMS guidelines identified a wide range in the quality of these guidelines and variable reporting of key elements of clinical guidelines. Future guideline developers should consider established methodological and reporting recommendations to improve the quality of EMS guidelines.

The Association between Supraphysiologic Arterial Oxygen Levels and Mortality in Critically Ill Patients. A Multicenter Observational Cohort Study

Rationale: There is conflicting evidence on harm related to exposure to supraphysiologic Pa_O2 (hyperoxemia) in critically ill patients.

Objectives: To examine the association between longitudinal exposure to hyperoxemia and mortality in patients admitted to ICUs in five United Kingdom university hospitals.

Methods: A retrospective cohort of ICU admissions between January 31, 2014, and December 31, 2018, from the National Institute of Health Research Critical Care Health Informatics Collaborative was studied. Multivariable logistic regression modeled death in ICU by exposure to hyperoxemia.

Measurements and Main Results: Subsets with oxygen exposure windows of 0 to 1, 0 to 3, 0 to 5, and 0 to 7 days were evaluated, capturing 19,515, 10,525, 6,360, and 4,296 patients, respectively. Hyperoxemia dose was defined as the area between the Pa_O2 time curve and a boundary of 13.3 kPa (100 mm Hg) divided by the hours of potential exposure (24, 72, 120, or 168 h). An association was found between exposure to hyperoxemia and ICU mortality for exposure windows of 0 to 1 days (odds ratio [OR], 1.15; 95% compatibility interval [CI], 0.95–1.38; P = 0.15), 0 to 3 days (OR 1.35; 95% CI, 1.04–1.74; P = 0.02), 0 to 5 days (OR, 1.5; 95% CI, 1.07–2.13; P = 0.02), and 0 to 7 days (OR, 1.74; 95% CI, 1.11–2.72; P = 0.02). However, a dose–response relationship was not observed. There was no evidence to support a differential effect between hyperoxemia and either a respiratory diagnosis or mechanical ventilation.

Conclusions: An association between hyperoxemia and mortality was observed in our large, unselected multicenter cohort. The absence of a dose–response relationship weakens causal interpretation. Further experimental research is warranted to elucidate this important question.

Non-tuberculous mycobacterial lung disease in patients with bronchiectasis: perceived risk, severity and guideline adherence in a European physician survey

BACKGROUND

Patients with bronchiectasis are at increased risk of developing non-tuberculous mycobacteria lung disease (NTM-LD), and published guidelines recommend regular testing for NTM infection in this patient population.

OBJECTIVE

This study aimed to survey physicians managing patients with bronchiectasis to understand the perceived risk of NTM to their patients, perceived disease severity and frequency of testing for NTM.

METHODS

The study comprised an online survey of hospital-based physicians in the UK, Germany, Italy, France and the Netherlands. The target group were hospital-based physicians who had managed at least 10 adult patients with bronchiectasis over the preceding 12 months.

RESULTS

In total, 280 physicians completed the survey. Most (87%) thought their patients to be at particular risk of NTM, although it was perceived as a moderate risk versus other respiratory pathogens. Most perceived NTM-LD to impact patient morbidity (84%), and 61% indicated that NTM-LD significantly impacted mortality. 68% of all respondents did not test for NTM prior to initiating macrolide monotherapy, despite guidelines recommending testing. The perceived risk of and screening for NTM varied among countries.

CONCLUSIONS

The study demonstrates that physicians understand the risk of NTM-LD and associated morbidity in patients with bronchiectasis; however, a minority do not perceive that NTM-LD significantly affects mortality. Greater awareness of the need to test for NTM infection before initiating macrolide monotherapy for bronchiectasis is essential due to potential emergence of drug-resistant NTM.

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome: insights from the LUNG SAFE study

Background

Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study.

Methods

In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO₂ > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO₂ ≥ 0.60 during hyperoxemia).

Results

Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO₂ < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO₂ use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO₂ use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO₂. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO₂ use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO₂ use, compared to 39% in a propensity-matched sample of normoxemic (PaO₂ 55–100 mmHg) patients (P = 0.47).

Conclusions

Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort.

Trial registration

LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073

Pulse oximetry saturation can predict prognosis of idiopathic pulmonary fibrosis

BACKGROUND

In Japan, the severity staging system for idiopathic pulmonary fibrosis (IPF) has been used to determine medical care subsidies. However, this system requires invasive procedures to measure arterial oxygen tension. Recently, noninvasive and simple measurements of oxygen saturation by pulse oximetry (SpO₂) have been used for severity assessments. We propose a pulse oximetry saturation (POS) staging system consisting of SpO₂ parameters to predict prognosis.

METHODS

We developed four prototype staging systems based on SpO₂ at rest and desaturation, and adopted the system with the highest C-statistic as the POS staging system. The cutoff SpO₂ values at rest were 96% and 90%, and desaturation was defined as SpO₂ < 90% at the end of the 6-min-walk test.

RESULTS

Two-hundred and nineteen IPF patients were studied and the C-statistic values of models 1, 2, 3, and 4 were 0.633, 0.643, 0.630, and 0.673, respectively. We judged model 4 to be a superior POS staging system; it defined SpO₂ ≥ 96% at rest without desaturation as stage Ⅰ; SpO₂ ≥ 96% at rest with desaturation or SpO₂ 90%-95% at rest without desaturation as stage Ⅱ; and SpO₂ 90%-95% at rest with desaturation or SpO₂ < 90% at rest as stage Ⅲ. The hazard ratios of POS stage Ⅰ, Ⅱ, and Ⅲ were 1.00, 2.25, and 4.99, respectively. The C-statistic of the POS staging system produced from 1000 bootstrap samples was similar (0.673), suggesting good internal validation.

CONCLUSION

A noninvasive and simple POS staging system defined by SpO₂ can easily predict prognosis.

The Search for Optimal Oxygen Saturation Targets in Critically Ill Patients: Observational Data From Large ICU Databases

BACKGROUND

Although low oxygen saturations are generally regarded as deleterious, recent studies in ICU patients have shown that a liberal oxygen strategy increases mortality. However, the optimal oxygen saturation target remains unclear. The goal of this study was to determine the optimal range by using real-world data.

METHODS

Replicate retrospective analyses were conducted of two electronic medical record databases: the eICU Collaborative Research Database (eICU-CRD) and the Medical Information Mart for Intensive Care III database (MIMIC). Only patients with at least 48 h of oxygen therapy were included. Nonlinear regression was used to analyze the association between median pulse oximetry-derived oxygen saturation (Spo2) and hospital mortality. We derived an optimal range of Spo2 and analyzed the association between the percentage of time within the optimal range of Spo2 and hospital mortality. All models adjusted for age, BMI, sex, and Sequential Organ Failure Assessment score. Subgroup analyses included ICU types, main diagnosis, and comorbidities.

RESULTS

The analysis identified 26,723 patients from eICU-CRD and 8,564 patients from MIMIC. The optimal range of Spo2 was 94% to 98% in both databases. The percentage of time patients were within the optimal range of Spo2 was associated with decreased hospital mortality (OR of 80% vs 40% of the measurements within the optimal range, 0.42 [95% CI, 0.40-0.43] for eICU-CRD and 0.53 [95% CI, 0.50-0.55] for MIMIC). This association was consistent across subgroup analyses.

CONCLUSIONS

The optimal range of Spo2 was 94% to 98% and should inform future trials of oxygen therapy.

Automated Home Oxygen Delivery for Patients with COPD and Respiratory Failure: A New Approach

Long-term oxygen therapy (LTOT) has become standard care for the treatment of patients with chronic obstructive pulmonary disease (COPD) and other severe hypoxemic lung diseases. The use of new portable O₂ concentrators (POC) in LTOT is being expanded. However, the issue of oxygen titration is not always properly addressed, since POCs rely on proper use by patients. The robustness of algorithms and the limited reliability of current oximetry sensors are hindering the effectiveness of new approaches to closed-loop POCs based on the feedback of blood oxygen saturation. In this study, a novel intelligent portable oxygen concentrator (iPOC) is described. The presented iPOC is capable of adjusting the O₂ flow automatically by real-time classifying the intensity of a patient’s physical activity (PA). It was designed with a group of patients with COPD and stable chronic respiratory failure. The technical pilot test showed a weighted accuracy of 91.1% in updating the O₂ flow automatically according to medical prescriptions, and a general improvement in oxygenation compared to conventional POCs. In addition, the usability achieved was high, which indicated a significant degree of user satisfaction. This iPOC may have important benefits, including improved oxygenation, increased compliance with therapy recommendations, and the promotion of PA.

Optimizing respiratory management in resource-limited settings

PURPOSE OF REVIEW

This review focuses on the emerging body of literature regarding the management of acute respiratory failure in low- and middle-income countries (LMICs). The aim is to abstract management principles that are of relevance across a variety of settings where resources are severely limited.

RECENT FINDINGS

Mechanical ventilation is an expensive intervention associated with considerable mortality and a high rate of iatrogenic complications in many LMICs. Recent case series report crude mortality rates for ventilated patients of between 36 and 72%. Measures to avert the need for invasive mechanical ventilation in LMICs are showing promise: bubble continuous positive airway pressure has been demonstrated to decrease mortality in children with acute respiratory failure and trials suggest that noninvasive ventilation can be conducted safely in settings where resources are low.

SUMMARY

The management of patients with acute respiratory failure in LMICs should focus on avoiding intubation where possible, improving the safety of mechanical ventilation and expediting weaning. Future directions should involve the development and trialing of robust and context-appropriate respiratory support technology.

Evaluation of hyperoxia-induced hypercapnia in obese patients after cardiac surgery: a randomized crossover comparison of conservative and liberal oxygen administration

PURPOSE

Recent studies on patients with stable obesity-hypoventilation syndrome have raised concerns about hyperoxia-induced hypercapnia in this population. This study aimed to evaluate whether a higher oxygen saturation target would increase arterial partial pressure of carbon dioxide (PaCO2) in obese patients after coronary artery bypass grafting surgery (CABG).

METHODS

Obese patients having CABG were recruited. With a randomized crossover design, we compared two oxygenation strategies for 30 min each, immediately after extubation: a peripheral oxygen saturation (SpO2) target of ≥ 95% achieved with manual oxygen titration (liberal) and a SpO2 target of 90% achieved with FreeO2, an automated oxygen titration device (conservative). The main outcome was end-of-period arterial PaCO2.

RESULTS

Thirty patients were included. Mean (standard deviation [SD]) body mass index (BMI) was 34 (3) kg·m-2 and mean (SD) baseline partial pressure of carbon dioxide (PCO2) was 40.7 (3.1) mmHg. Mean (SD) end-of-period PaCO2 was 42.0 (5.4) mmHg in the conservative period, compared with 42.6 (4.6) mmHg in the liberal period [mean difference - 0.6 (95% confidence interval - 2.2 to 0.9) mmHg; P = 0.4]. Adjusted analysis for age, BMI, narcotics, and preoperative PaCO2 did not substantively change the results. Fourteen patients were retainers, showing an elevation in mean (SD) PaCO2 in the liberal period of 3.3 (4.1) mmHg. Eleven patients had the opposite response, with a mean (SD) end-of-period PaCO2 decrease of 1.8 (2.2) mmHg in the liberal period. Five patients had a neutral response.

CONCLUSION

This study did not show a clinically important increase in PaCO2 associated with higher SpO2 values in this specific population of obese patients after CABG. Partial pressure of carbon dioxide increased with liberal oxygen administration in almost half of the patients, but no predictive factor was identified.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT02917668); registered 25 September, 2016.

Management of hypoxaemia in the critically ill patient

Hypoxaemia is a common presentation in critically ill patients, with the potential for severe harm if not addressed appropriately. This review provides a framework to guide the management of any hypoxaemic patient, regardless of the clinical setting. Key steps in managing such patients include ascertaining the severity of hypoxaemia, the underlying diagnosis and implementing the most appropriate treatment. Oxygen therapy can be delivered by variable or fixed rate devices, and non-invasive ventilation; if patients deteriorate they may require tracheal intubation and mechanical ventilation. Early critical care team involvement is a key part of this pathway. Specialist treatments for severe hypoxaemia can only be undertaken on an intensive care unit and this field is developing rapidly as trial results become available. It is important that each new scenario is approached in a structured manner with an open diagnostic mind and a clear escalation plan.

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.

High-flow nasal cannula versus conventional oxygen therapy in patients with dyspnea and hypoxemia before hospitalization

Introduction: Patients with dyspnea and hypoxemia are common in emergency departments. However, it is unknown whether high-flow nasal cannula (HFNC) reduces the risk of requiring more advanced ventilation support and whether HFNC relieves dyspnea better than conventional oxygen therapy (COT).Areas covered: We searched the PubMed, Cochrane Library, Ovid, and Embase databases from inception to 1 September 2019 to identify relevant-randomized controlled trials comparing the effect of HFNC with COT in emergency departments regarding the severity of dyspnea, hospitalization rate, intubation rate, and hospital mortality. We identified four studies. HFNC was associated with a lower rate of requiring more advanced ventilation. HFNC reduced the rate of dyspnea, lowered the dyspnea scale score, and decreased patients' respiratory rate significantly. However, there was insufficient evidence to show a significant effect on HFNC regarding patients' oxygenation and hospital mortality.Expert opinion: For patients with dyspnea and hypoxemia before hospitalization, the short-term effect of HFNC was undeniable. HFNC reduced the risk of requiring more advanced ventilation and relived dyspnea better than COT. HFNC might be considered as a first-line therapy even before making a clear diagnosis for dyspnea.More studies are needed to explore the effect of HFNC on oxygenation and patients' prognosis.

Effective decision-making: applying the theories to nursing practice

Many theories have been proposed for the decision-making conducted by nurses across all practices and disciplines. These theories are fundamental to consider when reflecting on our decision-making processes to inform future practice. In this article three of these theories are juxtaposed with a case study of a patient presenting with an ST-segment elevation myocardial infarction (STEMI). These theories are descriptive, normative and prescriptive, and will be used to analyse and interpret the process of decision-making within the context of patient assessment.

Oxygen therapy in the pre-hospital setting for acute exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a global leading cause of morbidity and mortality, characterised by acute deterioration in symptoms. During these exacerbations, people are prone to developing alveolar hypoventilation, which may be partly caused by the administration of high inspired oxygen concentrations.

OBJECTIVES

To determine the effect of different inspired oxygen concentrations ("high flow" compared to "controlled") in the pre-hospital setting (prior to casualty/emergency department) on outcomes for people with acute exacerbations of COPD (AECOPD).

SEARCH METHODS

The Cochrane Airways Group Specialised Register, reference lists of articles and online clinical trial databases were searched. Authors of identified randomised controlled trials (RCTs) were also contacted for details of other relevant published and unpublished studies. The most recent search was conducted on 16 September 2019.

SELECTION CRITERIA

We included RCTs comparing oxygen therapy at different concentrations or oxygen therapy versus placebo in the pre-hospital setting for treatment of AECOPD.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. The primary outcome was all-cause and respiratory-related mortality.

MAIN RESULTS

The search identified a total of 824 citations; one study was identified for inclusion and two studies are awaiting classification. The 214 participants involved in the included study were adults with AECOPD, receiving treatment by paramedics en route to hospital. The mean age of participants was 68 years. A reduction in pre/in-hospital mortality was observed in favour of the titrated oxygen group (two deaths in the titrated oxygen group compared to 11 deaths in the high-flow control arm; risk ratio (RR) 0.22, 95% confidence interval (CI) 0.05 to 0.97; 214 participants). This translates to an absolute effect of 94 per 1000 (high-flow oxygen) compared to 21 per 1000 (titrated oxygen), and a number needed to treat for an additional beneficial outcome (NNTB) of 14 (95% CI 12 to 355) with titrated oxygen therapy. Other than mortality, no other adverse events were reported in the included study. Wide confidence intervals were observed between groups for arterial blood gas (though this may be confounded by protocol infidelity in the included study for this outcome measure), treatment failure requiring invasive or non-invasive ventilation or hospital utilisation. No data were reported for quality of life, lung function or dyspnoea. Risk of bias within the included study was largely unclear, though there was high risk of bias in domains relating to performance and attrition bias. We judged the evidence to be of low certainty, according to GRADE criteria.

AUTHORS' CONCLUSIONS

The one included study found a reduction in pre/in-hospital mortality for the titrated oxygen arm compared to the high-flow control arm. However, the paucity of evidence somewhat limits the reliability of these findings and generalisability to other settings. There is a need for robust, well-designed RCTs to further investigate the effect of oxygen therapies in the pre-hospital setting for people with AECOPD.

Evaluation of a new respiratory monitoring tool "Early Warning ScoreO2" for patients admitted at the emergency department with dyspnea

BACKGROUND

Many scores derived from Early Warning Scores have been developed to detect patients at risk of poor outcome. Few of these scores incorporate the oxygen flow rate while this is a major marker in patients with respiratory complaint. We developed and evaluated a new automatable monitoring tool (Early Warning Score O₂: EWS.O₂) that incorporates cardio-respiratory parameters (Respiratory rate, Heart rate, SpO₂, and FiO₂ derived from oxygen flow rate), aiming to achieve early detection of poor outcome among patients with dyspnea.

METHODS

All patients presenting at an emergency department for dyspnea from June 2011 to June 2018 with available initial value (nurse triage) of respiratory parameters were included. Our primary endpoint was a composite criterion including the use of non-invasive ventilation, ICU admission and death. The Area under the Receiver Operating Characteristic curve (AUROC) of the SpO₂/FiO₂ index, NEWS, NEWS2, and the EWS.O₂ were compared, including in subgroup analysis by final diagnosis or oxygen supplementation.

RESULTS

Among the 1729 patients retrieved, the composite outcome was observed in 288 (16.7%). The EWS.O₂ displayed better or comparable predictive accuracy at triage (AUROC: 0.704, 95% CI 0.672-0.736) compared to NEWS (0.662, p < 0.01), NEWS2 (0.672, p = 0.02) and SpO₂/FiO₂ (0.695, p = 0.46).

CONCLUSIONS

This new ScoreO₂ is equivalent or superior to common early warning scores and index to predict poor outcome at first medical contact. This score may be automatically and continuously recorded with new closed-loop devices to titrate oxygen flow. Further prospective studies will allow to verify its accuracy at multiple time points of the patient's journey.

A multicentre prospective observational study comparing arterial blood gas values to those obtained by pulse oximeters used in adult patients attending Australian and New Zealand hospitals

Background

Pulse oximetry is widely used in the clinical setting. The purpose of this validation study was to investigate the level of agreement between oxygen saturations measured by pulse oximeter (SpO₂) and arterial blood gas (SaO₂) in a range of oximeters in clinical use in Australia and New Zealand.

Methods

Paired SpO₂ and SaO₂ measurements were collected from 400 patients in one Australian and two New Zealand hospitals. The ages of the patients ranged from 18 to 95 years. Bias and limits of agreement were estimated. Sensitivity and specificity for detecting hypoxaemia, defined as SaO₂ < 90%, were also estimated.

Results

The majority of participants were recruited from the Outpatient, Ward or High Dependency Unit setting. Bias, oximeter-measured minus arterial blood gas-measured oxygen saturation, was − 1.2%, with limits of agreement − 4.4 to 2.0%. SpO₂ was at least 4% lower than SaO₂ for 10 (2.5%) of the participants and SpO₂ was at least 4% higher than the SaO₂ in 3 (0.8%) of the participants. None of the participants with a SpO₂ ≥ 92% were hypoxaemic, defined as SaO₂ < 90%. There were no clinically significant differences in oximetry accuracy in relation to clinical characteristics or oximeter brand.

Conclusions

In the majority of the participants, pulse oximetry was an accurate method to assess SaO₂ and had good performance in detecting hypoxaemia. However, in a small proportion of participants, differences between SaO₂ and SpO₂ could have clinical relevance in terms of patient monitoring and management. A SpO₂ ≥ 92% indicates that hypoxaemia, defined as a SaO₂ < 90%, is not present.

Trial registration

Australian and New Zealand Clinical Trials Registry (ACTRN12614001257651). Date of registration: 2/12/2014.

Effect of oxygen supplement during targeted temperature management on acute lung injury in the early stage of traumatic hemorrhagic shock

Ideal concentrations of inhaled oxygen with regard to lung protection during early traumatic hemorrhagic shock (THS) remain unknown especially in the era of targeted temperature management (TTM). We speculated that a significant increase in oxygen supply in early stage of THS would magnify the protecting role of hypothermia in acute lung injury. Forty male New Zealand rabbits were randomly divided into four groups (n = 10): sham group, control group, group 1, and group 2. Except for sham group, all other animals were submitted to 30 min of uncontrolled THS and received limited fluid resuscitation for 60 min. During resuscitation, in addition to 34°C of TTM, animals in group 1 inhaled 21% oxygen while animals in group 2 inhaled 50% oxygen. Animals in control group inhaled room air and were kept normothermia. Oxidative stress, inflammation, and apoptosis parameters in the lung tissues were determined. THS induced higher expression of malondialdehyde, surfactant protein A, nuclear factor kappa B, and caspase 3 as well as lower expression of Bcl-2 mRNA and superoxide dismutase activity. Compared with inhalation of 21% oxygen, inhalation of 50% oxygen during TTM significantly improves oxidative stress, inflammation, apoptosis, and acute lung injury. Oxygen supplement during TTM therapy alleviated acute lung injury in the early stage of THS. Further studies are required to explore the ideal combination forms of TTM and oxygen supplement with the purpose of maximizing therapeutic effect while minimizing adverse effects.

Oxygen therapy versus conservative therapy in suspected uncomplicated myocardial infarction without hypoxemia: A meta-analysis of randomized controlled studies

Background:

The effect of oxygen therapy in patients with suspected uncomplicated myocardial infarction and without hypoxemia at baseline was uncertain.

Objectives:

We aimed to perform a rigorous and comprehensive meta-analysis to robustly quantify the efficacy of oxygen therapy in patients with suspected uncomplicated myocardial infarction and without hypoxemia at baseline.

Methods:

We searched EMBASE, MEDLINE, Web of Science, and the Cochrane Library from inception to August 2018. Two researchers screened studies and collected the data independently. Randomized controlled trials were included. The main outcome was mortality at the longest duration of follow-up.

Results:

Seven studies involving 7732 patients (median = 157 patients; range = 72–6629 patients; interquartile range = 136–441 patients; oxygen therapy group = 3856 patients; conservative group = 3876 patients) were included. Compared with conservative therapy, oxygen therapy did not significantly reduce mortality at the longest follow-up (risk ratio = 0.97; 95% confidence interval = 0.68 to 1.40; z = 0.15; p = 0.88), at discharge (risk ratio = 1.04; 95% confidence interval = 0.48 to 2.26; z = 0.11; p = 0.91), 30 days (risk ratio = 1.08; 95% confidence interval = 0.78 to 1.49; z = 0.44; p = 0.66), and 6 months (risk ratio = 0.93; 95% confidence interval = 0.73 to 1.17; z = 0.66; p = 0.51) in patients with suspected uncomplicated myocardial infarction and without hypoxemia at baseline. Furthermore, there was no significant difference between two groups with regard to infarct size (standard mean difference = 0.15, confidence interval = –0.13 to 0.44; z = 1.07, p = 0.28), cardiac troponin levels (standard mean difference = 0.30, confidence interval = –0.09 to 0.69; z = 1.51, p = 0.13), in hospital reinfarction (risk ratio = 1.49, confidence interval = 0.80 to 2.78; z = 1.25, p = 0.21), and new-onset atrial fibrillation (risk ratio = 0.91, confidence interval = 0.69 to 1.18; z = 0.72, p = 0.47). Multiple subgroup analysis, sensitivity analysis, and trial sequential analysis were consistent with overall findings.

Conclusion:

Compared with conservative therapy, oxygen therapy did not decrease the mortality at the longest duration of follow-up, discharge, 30 days, and 6 months in patients with suspected uncomplicated myocardial infarction and without hypoxemia at baseline. Furthermore, large-scale, multicenter studies are needed to confirm our results.

Registration:

PROSPERO, number CRD42017078807.

Implementing target range oxygen in critical care: A quality improvement pilot study

Background

Iatrogenic hyperoxaemia is common on critical care units and has been associated with increased mortality. We commenced a quality improvement pilot study to analyse the views and practice of critical care staff regarding oxygen therapy and to change practice to ensure that all patients have a prescribed target oxygen saturation range.

Methods

A baseline measurement of oxygen target range prescribing was undertaken alongside a survey of staff attitudes. We then commenced a programme of change, widely promoting an agreed oxygen target range prescribing policy. The analyses of target range prescribing and staff survey were repeated four to five months later.

Results

Thirty-three staff members completed the baseline survey, compared to 29 in the follow-up survey. There was no discernible change in staff attitudes towards oxygen target range prescribing. Fifty-four patients were included in the baseline survey and 124 patients were assessed post implementation of changes. The proportion of patients with an oxygen prescription with a target range improved from 85% to 95% (χ² = 5.17, p = 0.02) and the proportion of patients with an appropriate prescribed target saturation range increased from 85% to 91% (χ² = 1.4, p = 0.24). The improvement in target range prescribing was maintained at 96% 12 months later.

Conclusions

The introduction and promotion of a structured protocol for oxygen prescribing were associated with a sustained increase in the proportion of patients with a prescribed oxygen target range on this unit.

Breathlessness in palliative care: a practical guide

Breathlessness is a common symptom for patients with terminal illness and can be challenging to manage. Breathlessness is acknowledged to be an interaction between body and mind. There are a variety of pharmacological and non-pharmacological therapies that can be beneficial. The holistic assessment of the breathlessness patient should enable delivery of a tailored package of care focused on relief of symptoms.

Use of the ABCDE approach to assess a patient post-operatively: a case study

This article details a case study of the immediate post-operative care of an elective adult patient who presented in a postanaesthetic care unit. It outlines the systematic ABCDE (airway, breathing, circulation, disability and exposure) approach that was used to assess the patient and describes the actions that were taken to manage an airway obstruction that occurred. It also discusses the monitoring of patients required post-operatively, including capnography, peripheral oxygen saturations, blood pressure, temperature, heart rate and respiratory rate, which can assist in the identification and management of any issues and support optimal patient outcomes.

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.

The biology of pulmonary exacerbations in bronchiectasis

Bronchiectasis is a heterogeneous chronic disease. Heterogeneity characterises bronchiectasis not only in the stable state but also during exacerbations, despite evidence on clinical and biological aspects of bronchiectasis, exacerbations still remain poorly understood.Although the scientific community recognises that bacterial infection is a cornerstone in the development of bronchiectasis, there is a lack of data regarding other trigger factors for exacerbations. In addition, a huge amount of data suggest a primary role of neutrophils in the stable state and exacerbation of bronchiectasis, but the inflammatory reaction involves many other additional pathways. Cole's vicious cycle hypothesis illustrates how airway dysfunction, airway inflammation, infection and structural damage are linked. The introduction of the concept of a "vicious vortex" stresses the complexity of the relationships between the components of the cycle. In this model of disease, exacerbations work as a catalyst, accelerating the progression of disease. The roles of microbiology and inflammation need to be considered as closely linked and will need to be investigated in different ways to collect samples. Clinical and translational research is of paramount importance to achieve a better comprehension of the pathophysiology of bronchiectasis, microbiology and inflammation both in the stable state and during exacerbations.

Myocardial injury and mortality in patients with excessive oxygen administration before cardiac arrest

INTRODUCTION

Hyperoxia after cardiac arrest may be associated with higher mortality, and trials have found that excess oxygen administration in patients with myocardial infarction is associated with increased infarct size. The effect of hyperoxia before cardiac arrest is sparsely investigated. Our aim was to assess the association between excessive oxygen administration before cardiac arrest and the extent of subsequent myocardial injury.

METHODS

We performed a retrospective study including patients who had in-hospital cardiac arrest during 2014 in the Capital Region of Denmark. We excluded patients without peripheral oxygen saturation measurements within 48 hours before cardiac arrest. Patients were divided in three groups of pre-arrest oxygen exposure, based on average peripheral oxygen saturation and supplemental oxygen. Primary outcome was peak troponin concentration within 30 days. Secondary outcomes included 30-day mortality. Data were analyzed using multiple logistic regression and Wilcoxon rank sum test.

RESULTS

Of 163 patients with cardiac arrest, 28 had excessive oxygen administration (17%), 105 had normal oxygen administration (64%) and 30 had insufficient oxygen administration (18%) before cardiac arrest. Peak troponin was median 224 ng/L in the excessive oxygen administration group vs 365 ng/L in the normal oxygen administration group (P = .54); 20 of 28 (71%) in the excessive oxygen administration group died within 30 days compared to 54 of 105 (51%) in the normal oxygen administration group. (OR 1.87, 95% CI 0.56-6.19) CONCLUSIONS: Excessive oxygen administration within 48 hours before in-hospital cardiac arrest was not statistically associated with significantly higher peak troponin or mortality.

Effect of oxygen therapy on the risk of mechanical ventilation in emergency acute pulmonary edema patients

OBJECTIVE

We investigated the effects of hyperoxemia on morbidity and mortality in acute cardiogenic pulmonary edema (ACPE).

METHODS

We conducted a retrospective cohort study of patients in our emergency department (ED) with ACPE who received arterial blood gases. Patients were classified based on the first PaO2 as hypoxemic (<75 mmHg), normoxemic (75-100 mmHg) and hyperoxemic (>100 mmHg). The primary outcome was the rates of mechanical ventilation (MV). We also reported adjusted odds ratios (AOR) and their 95% confidence intervals (CI) of the primary outcome after adjusting for predictors of MV determined a priori. Secondary outcomes were median hospital length of stay (LOS) and in-hospital mortality.

RESULTS

We recruited 335 patients; 34.0% had hyperoxemia. The rates of normoxemia and hypoxemia were 27.5% and 38.5%, respectively. The rates of MV were: hypoxemic 60/129 (46.5%) vs. normoxemic 41/92 (44.6%) vs. hyperoxemic 50/114 (43.9%); P = 0.62. The AORs for MV for the hyperoxemic and hypoxemic groups (reference: normoxemic group) were 0.98 (95% CI: 0.53-1.79) and 1.38 (95% CI: 0.77-2.48), respectively. Intubation rates for the groups were: hypoxemic 15/129 (11.6%) vs. normoxemic 6/92 (6.5%) vs. hyperoxemic 12/114 (10.6%); P = 0.43. The secondary outcomes were comparable among the groups. In-hospital mortality rates were: hypoxemic 6/129 (4.7%) vs. 6/92 (6.5%) vs. 10/114 (8.8%); P = 0.42.

CONCLUSION

Our exploratory study did not report effects on mechanical ventilation, median hospital LOS and in-hospital mortality from hyperoxemia compared to hypoxemic and normoxemic ED patients with ACPE. Further studies are warranted to prove or disprove our findings.

Prognostic factors associated with long-term mortality in 1445 patients with nontuberculous mycobacterial pulmonary disease: a 15-year follow-up study

Limited data are available regarding the prognostic factors for patients with nontuberculous mycobacterial pulmonary disease (NTM-PD). We investigated the prognostic factors associated with long-term mortality in NTM-PD patients after adjusting for individual confounders, including aetiological organism and radiological form.

A total of 1445 patients with treatment-naïve NTM-PD who were newly diagnosed between July 1997 and December 2013 were included. The aetiological organisms were as follows: Mycobacterium avium (n=655), M. intracellulare (n=487), M. abscessus (n=129) and M. massiliense (n=174). The factors associated with mortality in NTM-PD patients were analysed using a multivariable Cox model after adjusting for demographic, radiological and aetiological data.

The overall 5-, 10- and 15-year cumulative mortality rates for the NTM-PD patients were 12.4%, 24.0% and 36.4%, respectively. On multivariable analysis, the following factors were significantly associated with mortality in NTM-PD patients: old age, male sex, low body mass index, chronic pulmonary aspergillosis, pulmonary or extrapulmonary malignancy, chronic heart or liver disease and erythrocyte sedimentation rate. The aetiological organism was also significantly associated with mortality: M. intracellulare had an adjusted hazard ratio (aHR) of 1.40, 95% CI 1.03–1.91; M. abscessus had an aHR of 2.19, 95% CI 1.36–3.51; and M. massiliense had an aHR of 0.99, 95% CI 0.61–1.64, compared to M. avium. Mortality was also significantly associated with the radiological form of NTM-PD for the cavitary nodular bronchiectatic form (aHR 1.70, 95% CI 1.12–2.59) and the fibrocavitary form (aHR 2.12, 95% CI 1.57–3.08), compared to the non-cavitary nodular bronchiectatic form.

Long-term mortality in patients with NTM-PD was significantly associated with the aetiological NTM organism, cavitary disease and certain demographic characteristics.

Oxygen devices and delivery systems

Oxygen use has extended from inpatient to outpatient settings for patients with chronic pulmonary diseases and complications of hypoxaemia. This article presents an overview of oxygen devices (oxygen concentrators, compressed gas cylinders and liquid oxygen) and delivery systems (high- and low-flow). The indications, advantages and disadvantages of each device and delivery system are presented, aiming to offer updated knowledge to the multidisciplinary team members managing patients with respiratory failure, and therefore allowing appropriate selection of devices and delivery systems that are tailored to the needs of each patient.

A Pervasive Healthcare System for COPD Patients

Chronic obstructive pulmonary disease (COPD) is one of the most severe public health problems worldwide. Pervasive computing technology creates a new opportunity to redesign the traditional pattern of medical system. While many pervasive healthcare systems are currently found in the literature, there is little published research on the effectiveness of these paradigms in the medical context. This paper designs and validates a rule-based ontology framework for COPD patients. Unlike conventional systems, this work presents a new vision of telemedicine and remote care solutions that will promote individual self-management and autonomy for COPD patients through an advanced decision-making technique. Rules accuracy estimates were 89% for monitoring vital signs, and environmental factors, and 87% for nutrition facts, and physical activities.

Effects of inspired oxygen concentration during emergence from general anaesthesia on postoperative lung impedance changes evaluated by electrical impedance tomography: a randomised controlled trial

We evaluated the effects of three different inspired oxygen concentrations (40%, 80%, and 100%) at anaesthesia emergence on postoperative lung volumes as measured by global impedance of electrical impedance tomography (EIT). This is a randomised, controlled, and assessor-blinded study in single-centre from May 2017 to August 2017. Seventy-one patients undergoing elective laparoscopic colorectal surgery with healthy lung condition were randomly allocated into the three groups based on the concentration of inspired oxygen applied during anaesthesia emergence: 40%-, 80%- or 100%-oxygen. End-expiratory lung impedance (EELI) with normal tidal ventilation and total lung impedance (TLI) with full respiratory effort were measured preoperatively and before discharge in the post-anaesthesia care unit by EIT, and perioperative changes (the ratio of difference between preoperative and postoperative value to preoperative value) were compared among the three groups. Postoperative lung impedances were significantly reduced compared with preoperative values in all patients (P < 0.001); however, perioperative lung impedance reduction (%) did not differ among the three oxygen groups. The mean reduction ratio in each 40%-, 80%-, and 100%-oxygen group were 37% ± 13%, 41% ± 14%, and 46% ± 14% for EELI (P = 0.125) and 40% ± 20%, 44% ± 17% and 49% ± 20% for TLI (P = 0.276), respectively. Inspired oxygen concentrations applied during anaesthesia emergence did not show a significant difference in postoperative lung volume as measured by EIT in patients undergoing laparoscopic colorectal surgery with healthy lungs.Trial registration cris.nih.go.kr (KCT0002642).

Oxygen therapy in acute resuscitation

PURPOSE OF REVIEW

Avoidance and treatment of hypoxaemia is a cornerstone of acute resuscitation and yet the optimal approach to oxygen therapy in the acute care setting is uncertain. The aim of this review is to appraise recent evidence relating to the provision of supplemental oxygen to adult patients with acute illnesses with a focus on the resuscitation phase.

RECENT FINDINGS

Recent findings generally support the notion that exposure to hyperoxaemia is associated with adverse outcomes in acutely ill adults with a range of diseases and raise the possibility that liberal provision of oxygen may cause harm. Several ongoing multicentre randomized trials aim to assess the effects of different oxygen therapy regimens on patient outcomes to provide a foundation for evidence-based recommendations regarding the use of supplemental oxygen in Intensive Care Unit patients.

SUMMARY

At present, evidence is lacking to support routine liberal oxygen administration in acutely ill patients and, in most circumstances, a reasonable approach is to titrate supplemental oxygen to achieve an arterial oxygen saturation measured by pulse oximetry (SpO2) of 92-96% with the aim of avoiding both hypoxaemia and hyperoxaemia.

Predictors of success of high-flow nasal cannula in the treatment of acute hypoxemic respiratory failure

BACKGROUND

High-flow nasal cannula (HFNC) therapy is used in the treatment of acute respiratory failure (ARF) and is both safe and effective in reversing hypoxemia. In order to minimize mortality and clinical complications associated to this practice, a series of tools must be developed to allow early detection of failure. The present study was carried out to: (i)examine the impact of respiratory rate (RR), peripheral oxygen saturation (SpO₂), ROX index (ROXI=[SpO₂/FiO₂]/RR) and oxygen inspired fraction (FiO₂) on the success of HFNC in patients with hypoxemic ARF; and (ii)analyze the length of stay and mortality in the ICU, and the need for mechanical ventilation (MV).

METHODS

A retrospective study was carried out in the medical-surgical ICU of Hospital de Montilla (Córdoba, Spain). Patients diagnosed with hypoxemic ARF and treated with HFNC from January 2016 to January 2018 were included.

RESULTS

Out of 27 patients diagnosed with ARF, 19 (70.37%) had hypoxemic ARF. Fifteen of them (78.95%) responded satisfactorily to HFNC, while four (21.05%) failed. After two hours of treatment, RR proved to be the best predictor of success (area under the ROC curve [AUROC] 0.858; 95%CI: 0.63-1.05; P=.035). For this parameter, the optimal cutoff point was 29rpm (sensitivity 75%, specificity 87%). After 8hours of treatment, FiO₂ and ROXI were reliable predictors of success (FiO₂: AUROC 0.95; 95%CI: 0.85-1.04; P=.007 and ROXI: AUROC 0.967; 95%CI: 0.886-1.047; P=.005). In the case of FiO₂ the optimal cutoff point was 0.59 (sensitivity 75%, specificity 93%), while the best cutoff point for ROXI was 5.98 (sensitivity 100%, specificity 75%). Using a Cox regression model, we found RR<29rpm after two hours of treatment, and FiO₂<0.59 and ROXI>5.98 after 8hours of treatment, to be associated with a lesser risk of MV (RR: HR 0.103; 95%CI: 0.11-0.99; P=.05; FiO₂: HR 0.053; 95%CI: 0.005-0.52; P=.012; and ROXI: HR 0.077; 95%CI: 0.008-0.755; P=.028, respectively).

CONCLUSIONS

RR after two hours of treatment, and FiO₂ and ROXI after 8hours of treatment, were the best predictors of success of HFNC. RR<29rpm, FiO₂<0.59 and ROXI>5.98 were associated with a lesser risk of MV.

Choosing an Adequate Test to Determine Fitness for Air Travel in Obese Individuals

BACKGROUND

Air travel is physically demanding and, because obesity is rising, physicians increasingly need to assess whether such patients can fly safely. Our aim was to compare the diagnostic accuracy of two routinely used exercise tests, 50-m walk test and 6-min walk test, and hypoxic challenge testing (HCT) in obese individuals. We further explored the diagnostic potential of perceived dyspnea as measured with the Borg scale because this is often recorded subsequent to walking tests.

METHODS

In this prospective study, we examined 21 obese participants (10 women, age 51 ± 15 [mean  ±  SD], BMI 36 ± 5  kg/m²). The most prevalent comorbidity was COPD (n = 11). The reference standard for in-flight hypoxia, defined as oxygen saturation below 90%, was established in an altitude chamber. Diagnostic accuracy of each index test was estimated by area under the receiver operating characteristic curve (AUC).

RESULTS

Of the 21 participants, 13 (9 with COPD) were identified with in-flight hypoxia. HCT was the only test separating the reference groups significantly with AUC 0.87 (95% CI,  0.62-0.96). Neither of the walking tests predicted noticeably above chance level: 50 m walk test had an AUC of 0.63 (0.36-0.84) and 6MWT had an AUC of 0.64 (0.35-0.86). We further observed good prognostic ability of subjective dyspnea assessment when recorded after 6MWT with an AUC of 0.80 (0.55-0.93).

CONCLUSIONS

In-flight hypoxia in obese individuals can be predicted by HCT but not by simple walking tests.

Comparison of early warning scores in patients with COPD exacerbation: DECAF and NEWS score

Background

The National Early Warning Score 2 (NEWS2) includes two oxygen saturation scales; the second adjusts target saturations to 88%–92% for those with hypercapnic respiratory failure. Using this second scale in all patients with COPD exacerbation (‘NEWS2_{All COPD}’) would simplify practice, but the impact on alert frequency and prognostic performance is unknown. Admission NEWS2 score has not been compared with DECAF (dyspnoea, eosinopenia, consolidation, acidaemia, atrial fibrillation) for inpatient mortality prediction.

Methods

NEWS, NEWS2 and NEWS2_{All COPD} and DECAF were calculated at admission in 2645 patients with COPD exacerbation attending consecutively to one of six UK hospitals, all of whom met spirometry criteria for COPD. Alert frequency and appropriateness were assessed for all NEWS iterations. Prognostic performance was compared using the area under the receiver operating characteristic (AUROC) curve. Missing data were imputed using multiple imputation.

Findings

Compared with NEWS, NEWS2 reclassified 3.1% patients as not requiring review by a senior clinician (score≥5). NEWS2_{All COPD} reduced alerts by 12.6%, or 16.1% if scoring for injudicious use of oxygen was exempted. Mortality was low in reclassified patients, with no patients dying the same day as being identified as low risk. NEWS2_{All COPD} was a better prognostic score than NEWS (AUROC 0.72 vs 0.65, p<0.001), with similar performance to NEWS2 (AUROC 0.72 vs 0.70, p=0.090). DECAF was superior to all scores (validation cohort AUROC 0.82) and offered a more clinically useful range of risk stratification (DECAF=1.2%–25.5%; NEWS2=3.5%–15.4%).

Conclusion

NEWS2_{All COPD} safely reduces the alert frequency compared with NEWS2. DECAF offers superior prognostic performance to guide clinical decision-making on admission, but does not replace repeated measures of NEWS2 during hospitalisation to detect the deteriorating patient.

Time to NIV and mortality in AECOPD hospital admissions: an observational study into real world insights from National COPD Audits

Background

Randomised control trial (RCT)-derived survival figures for acute exacerbation of chronic obstructive pulmonary disease admissions managed with non-invasive ventilation (NIV) have not been replicated in UK clinical audits. Subsequent guidelines have emphasised the need for timely NIV application.

Methods

Data from the 2008 and 2014 national chronic obstructive pulmonary disease audits was used to analyse the association between time to NIV and mortality.

Results

1032 patients received NIV in 2008, and 1612 in 2014. Overall mortality rates reduced between the audits from 24.9% in 2008 to 16.8% in 2014 but time to NIV lengthened. In 2014, 20.9% of patients received NIV within 60 min versus 24.9% in 2008 (p=0.001). The proportion of patients receiving NIV between 3 and 24 hours increased from 31.3% in 2008 to 39% in 2014 (p=0.001). Patients admitted with hypercapnic acidotic respiratory failure who received NIV within 3 hours had lower in-patient mortality than those who received NIV between 3 and 24 hours, 15.9% versus 18.4%, but this did not reach statistical significance (p=0.425), but acidotic patients receiving NIV >24 hours after admission had significantly higher mortality (28.9%, p=0.002). A second cohort admitted with hypercapnia but normal range pH, who developed later acidosis, had higher mortality (24.6%), compared with those acidotic on admission (18% p≤0.001) and an extremely high mortality when NIV was given >24 hours after admission (42.6%).

Conclusion

Survival rates for those treated with NIV has improved between the two audits but remains lower than reported in RCTs. Patients who developed acidosis after admission and received NIV later in the hospital stay have even higher mortality and deserve further study and clinical attention.

Association of Severe Hyperoxemia Events and Mortality Among Patients Admitted to a Pediatric Intensive Care Unit

Importance

A high Pao2, termed hyperoxemia, is postulated to have deleterious health outcomes. To date, the association between hyperoxemia during the ongoing management of critical illness and mortality has been incompletely evaluated in children.

Objective

To examine whether severe hyperoxemia events are associated with mortality among patients admitted to a pediatric intensive care unit (PICU).

Design, Setting, and Participants

A retrospective cohort study was conducted over a 10-year period (January 1, 2009, to December 31, 2018); all 23 719 PICU encounters at a quaternary children's hospital with a documented arterial blood gas measurement were evaluated.

Exposures

Severe hyperoxemia, defined as Pao2 level greater than or equal to 300 mm Hg (40 kPa).

Main Outcomes and Measures

The highest Pao2 values during hospitalization were dichotomized according to the definition of severe hyperoxemia and assessed for association with in-hospital mortality using logistic regression models incorporating a calibrated measure of multiple organ dysfunction, extracorporeal life support, and the total number of arterial blood gas measurements obtained during an encounter.

Results

Of 23 719 PICU encounters during the inclusion period, 6250 patients (13 422 [56.6%] boys; mean [SD] age, 7.5 [6.6] years) had at least 1 measured Pao2 value. Severe hyperoxemia was independently associated with in-hospital mortality (adjusted odds ratio [aOR], 1.78; 95% CI, 1.36-2.33; P < .001). Increasing odds of in-hospital mortality were observed with 1 (aOR, 1.47; 95% CI, 1.05-2.08; P = .03), 2 (aOR, 2.01; 95% CI, 1.27-3.18; P = .002), and 3 or more (aOR, 2.53; 95% CI, 1.62-3.94; P < .001) severely hyperoxemic Pao2 values obtained greater than or equal to 3 hours apart from one another compared with encounters without hyperoxemia. A sensitivity analysis examining the hypothetical outcomes of residual confounding indicated that an unmeasured binary confounder with an aOR of 2 would have to be present in 37% of the encounters with severe hyperoxemia and 0% of the remaining cohort to fail to reject the null hypothesis (aOR of severe hyperoxemia, 1.31; 95% CI, 0.99-1.72).

Conclusions and Relevance

Greater numbers of severe hyperoxemia events appeared to be associated with increased mortality in this large, diverse cohort of critically ill children, supporting a possible exposure-response association between severe hyperoxemia and outcome in this population. Although further prospective evaluation appears to be warranted, this study's findings suggest that guidelines for ongoing management of critically ill children should take into consideration the possible detrimental effects of severe hyperoxemia.

Handling Oxygenation Targets in the Intensive Care Unit (HOT-ICU)-Protocol for a randomised clinical trial comparing a lower vs a higher oxygenation target in adults with acute hypoxaemic respiratory failure

BACKGROUND

Acutely ill adults with hypoxaemic respiratory failure are at risk of life-threatening hypoxia, and thus oxygen is often administered liberally. Excessive oxygen use may, however, increase the number of serious adverse events, including death. Establishing the optimal oxygenation level is important as existing evidence is of low quality. We hypothesise that targeting an arterial partial pressure of oxygen (PaO₂ ) of 8 kPa is superior to targeting a PaO₂ of 12 kPa in adult intensive care unit (ICU) patients with acute hypoxaemic respiratory failure.

METHODS

The Handling Oxygenation Targets in the ICU (HOT-ICU) trial is an outcome assessment blinded, multicentre, randomised, parallel-group trial targeting PaO₂ in acutely ill adults with hypoxaemic respiratory failure within 12 hours after ICU admission. Patients are randomised 1:1 to one of the two PaO₂ targets throughout ICU stay until a maximum of 90 days. The primary outcome is 90-day mortality. Secondary outcomes are serious adverse events in the ICU, days alive without organ support and days alive out of hospital in the 90-day period; mortality, health-related quality-of-life at 1-year follow-up as well as 1-year cognitive and pulmonary function in a subgroup; and an overall health economic analysis. To detect or reject a 20% relative risk reduction, we aim to include 2928 patients. An interim analysis is planned after 90-day follow-up of 1464 patients.

CONCLUSION

The HOT-ICU trial will test the hypothesis that a lower oxygenation target reduces 90-day mortality compared with a higher oxygenation target in adult ICU patients with acute hypoxaemic respiratory failure.

Augmenting Critical Care Capacity in a Disaster

A health care facility must develop a comprehensive disaster plan that has a provision for critical care services. Mass critical care requires surge capacity: augmentation of critical care services during a disaster. Surge capacity involves staff, supplies, space, and structure. Measures to increase critical care staff include recalling essential personnel, using noncritical care staff, and emergency credentialing of volunteers. Having an adequate supply chain and a cache of critical care supplies is essential. Virtual critical care or tele-critical care can augment critical care capacity by assisting with patient monitoring, specialized consultation, and in pandemics reduces staff exposure.

M ycobacterium abscessus pulmonary disease: individual patient data meta-analysis

Treatment of Mycobacterium abscessus pulmonary disease (MAB-PD), caused by M. abscessus subsp. abscessus, M. abscessus subsp. massiliense or M. abscessus subsp. bolletii, is challenging.We conducted an individual patient data meta-analysis based on studies reporting treatment outcomes for MAB-PD to clarify treatment outcomes for MAB-PD and the impact of each drug on treatment outcomes. Treatment success was defined as culture conversion for ≥12 months while on treatment or sustained culture conversion without relapse until the end of treatment.Among 14 eligible studies, datasets from eight studies were provided and a total of 303 patients with MAB-PD were included in the analysis. The treatment success rate across all patients with MAB-PD was 45.6%. The specific treatment success rates were 33.0% for M. abscessus subsp. abscessus and 56.7% for M. abscessus subsp. massiliense For MAB-PD overall, the use of imipenem was associated with treatment success (adjusted odds ratio (aOR) 2.65, 95% CI 1.36-5.10). For patients with M. abscessus subsp. abscessus, the use of azithromycin (aOR 3.29, 95% CI 1.26-8.62), parenteral amikacin (aOR 1.44, 95% CI 1.05-1.99) or imipenem (aOR 7.96, 95% CI 1.52-41.6) was related to treatment success. For patients with M. abscessus subsp. massiliense, the choice among these drugs was not associated with treatment outcomes.Treatment outcomes for MAB-PD are unsatisfactory. The use of azithromycin, amikacin or imipenem was associated with better outcomes for patients with M. abscessus subsp. abscessus.

Non-tuberculous mycobacterial pulmonary disease

Nontuberculous mycobacterial pulmonary disease (NTM-PD) is a challenging infection which is becoming increasingly prevalent, particularly in the elderly, for reasons which are unknown. While underlying lung disease is a well-established risk factor for NTM-PD, it may also occur in apparently healthy individuals. No single common genetic or immunological defect has been identified in this group, and it is likely that multiple pathways contribute towards host susceptibility to NTM-PD which further interact with environmental and microbiological factors leading to the development of disease.The diagnosis of NTM-PD relies on the integration of clinical, radiological and microbiological results. The clinical course of NTM-PD is heterogeneous, with some patients remaining stable without the need for treatment and others developing refractory disease associated with considerable mortality and morbidity. Treatment regimens are based on the identity of the isolated species, drug sensitivity testing (for some agents) and the severity of disease. Multiple antibiotics are typically required for prolonged periods of time and treatment is frequently poorly tolerated. Surgery may be beneficial in selected cases. In some circumstances cure may not be attainable and there is a pressing need for better regimens to treat refractory and drug-resistant NTM-PD.This review summarises current knowledge on the epidemiology, aetiology and diagnosis of NTM-PD and discusses the treatment of two of the most clinically significant species, the M. avium and M. abscessus complexes, with a focus on refractory disease and novel therapies.

Oxygen alert wristbands (OxyBand) and controlled oxygen: a pilot study

Despite the introduction of Oxygen Alert Cards, guidelines and audits, oxygen therapy remains overused in NHS practice, and this may lead to iatrogenic mortality. This pilot study aimed to examine the use of Oxygen Alert Wristbands (OxyBand) designed to alert health professionals who are delivering oxygen to patients to ensure that the oxygen is administered and titrated safely to the appropriate target saturations. Patients at risk of hypercapnic acidosis were asked to wear OxyBands while presenting to paramedics and health professionals in hospitals. Inappropriate prescription of oxygen reduced significantly after the OxyBands were used. A questionnaire-based assessment showed that the clinicians involved had a good understanding of the risks of uncontrolled oxygen. Forty-two patients found the wrist band comfortable to wear, and only two did not. OxyBands may have the potential to improve patient safety over Oxygen Alert Cards.