Magnitude and time to peak oxygenation effect of prone positioning in ventilated adults with COVID-19 related acute hypoxemic respiratory failure

BACKGROUND

Prone positioning may improve oxygenation in acute hypoxemic respiratory failure and was widely adopted in COVID-19 patients. However, the magnitude and timing of its peak oxygenation effect remain uncertain with the optimum dosage unknown. Therefore, we aimed to investigate the magnitude of the peak effect of prone positioning on the PaO2 :FiO2 ratio during prone and secondly, the time to peak oxygenation.

METHODS

Multi-centre, observational study of invasively ventilated adults with acute hypoxemic respiratory failure secondary to COVID-19 treated with prone positioning. Baseline characteristics, prone positioning and patient outcome data were collected. All arterial blood gas (ABG) data during supine, prone and after return to supine position were analysed. The magnitude of peak PaO2 :FiO2 ratio effect and time to peak PaO2 :FIO2 ratio effect was measured.

RESULTS

We studied 220 patients (mean age 54 years) and 548 prone episodes. Prone positioning was applied for a mean (±SD) 3 (±2) times and 16 (±3) hours per episode. Pre-proning PaO2 :FIO2 ratio was 137 (±49) for all prone episodes. During the first episode. the mean PaO2 :FIO2 ratio increased from 125 to a peak of 196 (p < .001). Peak effect was achieved during the first episode, after 9 (±5) hours in prone position and maintained until return to supine position.

CONCLUSIONS

In ventilated adults with COVID-19 acute hypoxemic respiratory failure, peak PaO2 :FIO2 ratio effect occurred during the first prone positioning episode and after 9 h. Subsequent episodes also improved oxygenation but with diminished effect on PaO2 :FIO2 ratio. This information can help guide the number and duration of prone positioning episodes.

PRECISION-TBI: a study protocol for a vanguard prospective cohort study to enhance understanding and management of moderate to severe traumatic brain injury in Australia

INTRODUCTION

Traumatic brain injury (TBI) is a heterogeneous condition in terms of pathophysiology and clinical course. Outcomes from moderate to severe TBI (msTBI) remain poor despite concerted research efforts. The heterogeneity of clinical management represents a barrier to progress in this area. PRECISION-TBI is a prospective, observational, cohort study that will establish a clinical research network across major neurotrauma centres in Australia. This network will enable the ongoing collection of injury and clinical management data from patients with msTBI, to quantify variations in processes of care between sites. It will also pilot high-frequency data collection and analysis techniques, novel clinical interventions, and comparative effectiveness methodology.

METHODS AND ANALYSIS

PRECISION-TBI will initially enrol 300 patients with msTBI with Glasgow Coma Scale (GCS) <13 requiring intensive care unit (ICU) admission for invasive neuromonitoring from 10 Australian neurotrauma centres. Demographic data and process of care data (eg, prehospital, emergency and surgical intervention variables) will be collected. Clinical data will include prehospital and emergency department vital signs, and ICU physiological variables in the form of high frequency neuromonitoring data. ICU treatment data will also be collected for specific aspects of msTBI care. Six-month extended Glasgow Outcome Scores (GOSE) will be collected as the key outcome. Statistical analysis will focus on measures of between and within-site variation. Reports documenting performance on selected key quality indicators will be provided to participating sites.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from The Alfred Human Research Ethics Committee (Alfred Health, Melbourne, Australia). All eligible participants will be included in the study under a waiver of consent (hospital data collection) and opt-out (6 months follow-up). Brochures explaining the rationale of the study will be provided to all participants and/or an appropriate medical treatment decision-maker, who can act on the patient's behalf if they lack capacity. Study findings will be disseminated by peer-review publications.

TRIAL REGISTRATION NUMBER

NCT05855252.

Neuromuscular blockade and oxygenation changes during prone positioning in COVID-19

PURPOSE

Neuromuscular blockers (NMBs) are often used during prone positioning to facilitate mechanical ventilation in COVID-19 related ARDS. However, their impact on oxygenation is uncertain.

METHODS

Multi-centre observational study of invasively ventilated COVID-19 ARDS adults treated with prone positioning. We collected data on baseline characteristics, prone positioning, NMB use and patient outcome. We assessed arterial blood gas data during supine and prone positioning and after return to the supine position.

RESULTS

We studied 548 prone episodes in 220 patients (mean age 54 years, 61% male) of whom 164 (75%) received NMBs. Mean PaO2:FiO2 (P/F ratio) during the first prone episode with NMBs reached 208 ± 63 mmHg compared with 161 ± 66 mmHg without NMBs (Δmean = 47 ± 5 mmHg) for an absolute increase from baseline of 76 ± 56 mmHg versus 55 ± 56 mmHg (padj < 0.001). The mean P/F ratio on return to the supine position was 190 ± 63 mmHg in the NMB group versus 141 ± 64 mmHg in the non-NMB group for an absolute increase from baseline of 59 ± 58 mmHg versus 34 ± 56 mmHg (padj < 0.001).

CONCLUSION

During prone positioning, NMB is associated with increased oxygenation compared to non-NMB therapy, with a sustained effect on return to the supine position. These findings may help guide the use of NMB during prone positioning in COVID-19 ARDS.

The Impact of Sedative Choice on Intracranial and Systemic Physiology in Moderate to Severe Traumatic Brain Injury: A Scoping Review

Although sedative use is near-ubiquitous in the acute management of moderate to severe traumatic brain injury (m-sTBI), the evidence base for these agents is undefined. This review summarizes the evidence for analgosedative agent use in the intensive care unit management of m-sTBI. Clinical studies of sedative and analgosedative agents currently utilized in adult m-sTBI management (propofol, ketamine, benzodiazepines, opioids, and alpha-2 agonists) were identified and assessed for relevance and methodological quality. The primary outcome was the effect of the analgosedative agent on intracranial pressure (ICP). Secondary outcomes included intracranial hemodynamic and metabolic parameters, systemic hemodynamic parameters, measures of therapeutic intensity, and clinical outcomes. Of 594 articles identified, 61 met methodological review criteria, and 40 were included in the qualitative summary; of these, 33 were prospective studies, 18 were randomized controlled trials, and 8 were blinded. There was consistent evidence for the efficacy of sedative agents in the management of m-sTBI and raised ICP, but the overall quality of the evidence was poor, consisting of small studies (median sample size, 23.5) of variable methodological quality. Propofol and midazolam achieve the goals of sedation without notable differences in efficacy or safety, although high-dose propofol may disrupt cerebral autoregulation. Dexmedetomidine and propofol/ dexmedetomidine combination may cause clinically significant hypotension. Dexmedetomidine was effective to achieve a target sedation score. De novo opioid boluses were associated with increased ICP and reduced cerebral perfusion pressure. Ketamine bolus and infusions were not associated with increased ICP and may reduce the incidence of cortical spreading depolarization events. In conclusion, there is a paucity of high-quality evidence to inform the optimal use of analgosedative agents in the management of m-sTBI, inferring significant scope for further research.

Development of Traumatic Brain Injury Associated Intracranial Hypertension Prediction Algorithms: A Narrative Review

Traumatic intracranial hypertension (tIH) is a common and potentially lethal complication of moderate to severe traumatic brain injury (m-sTBI). It often develops with little warning and is managed reactively with the tiered application of intracranial pressure (ICP)-lowering interventions administered in response to an ICP rising above a set threshold. For over 45 years, a variety of research groups have worked toward the development of technology to allow for the preemptive management of tIH in the hope of improving patient outcomes. In 2022, the first operationalizable tIH prediction system became a reality. With such a system, ICP lowering interventions could be administered prior to the rise in ICP, thus protecting the patient from potentially damaging tIH episodes and limiting the overall ICP burden experienced. In this review, we discuss related approaches to ICP forecasting and IH prediction algorithms, which collectively provide the foundation for the successful development of an operational tIH prediction system. We also discuss operationalization and the statistical assessment of tIH algorithms. This review will be of relevance to clinicians and researchers interested in development of this technology as well as those with a general interest in the bedside application of machine learning (ML) technology.

Study protocol and statistical analysis plan for the 20% Human Albumin Solution Fluid Bolus Administration Therapy in Patients after Cardiac Surgery-ll (HAS FLAIR-II) trial

Background: Fluid bolus therapy with 20% albumin may shorten the duration of vasopressor therapy in patients after cardiac surgery. Objective: To describe the study protocol and statistical analysis plan for the 20% Human Albumin Solution Fluid Bolus Administration Therapy in Patients after Cardiac Surgery-II (HAS FLAIR-II) trial. Design, setting, participants and intervention: HAS FLAIR-II is a phase 2b, multicentre, parallel group, openlabel, randomised controlled trial that will be conducted at six Australian intensive care units. Patients requiring fluid bolus therapy after cardiac surgery will be randomly assigned in a 1:1 ratio to the intervention of fluid bolus therapy with 20% albumin or a comparator of fluid bolus therapy with a crystalloid solution. Main outcome measures: The primary outcome measure is the cumulative duration of vasopressor therapy. Secondary outcomes include vasopressor use, service utilisation, and mortality. All analyses will be conducted on an intention-to-treat basis. Results and conclusion: The study protocol and statistical analysis plan will guide the conduct and analysis of the HAS FLAIR-II trial, such that analytical and reporting biases are minimised. Trial registration: This trial has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN No. 12620000137998).

Early sedation in traumatic brain injury: a multicentre international observational study

Objectives: We aimed to investigate the use of sedation in patients with severe traumatic brain injury (TBI), focusing on the choice of sedative agent, dose, duration, and their association with clinical outcomes. Design: Multinational, multicentre, retrospective observational study. Settings: 14 trauma centres in Europe, Australia and the United Kingdom. Participants: A total of 262 adult patients with severe TBI and intracranial pressure monitoring. Main outcome measures: We described how sedative agents were used in this population. The primary outcome was 60-day mortality according to the use of different sedative agents. Secondary outcomes included intensive care unit and hospital length of stay, and the Extended Glasgow Outcome Scale at hospital discharge. Results: Propofol and midazolam were the most commonly used sedatives. Propofol was more common than midazolam as first line therapy (35.4% v 25.6% respectively). Patients treated with propofol had similar Acute Physiology and Chronic Health Evaluation (APACHE) II and International Mission for Prognosis and Analysis of Clinical Trials in Traumatic Brain Injury (IMPACT) scores to patients treated with midazolam, but lower Injury Severity Score (ISS) (median, 26 [IQR, 22-38] v 34 [IQR, 26-44]; P = 0.001). The use of propofol was more common in heavier patients, and midazolam use was strongly associated with opioid co-administration (OR, 12.9; 95% CI, 3.47-47.95; P < 0.001). Sixty-day mortality and hospital mortality were predicted by a higher IMPACT score (P < 0.001) and a higher ISS (P < 0.001), but, after adjustment, were not related to the choice of sedative agent. Conclusions: Propofol was used more often than midazolam, and large doses were common for both sedatives. The first choice was highly variable, was affected by injury severity, and was not independently associated with 60-day mortality.

Teaching the Teachers: A Flexible, Cognitive-Focused Curriculum in Point-of-Care Ultrasound Education for Hospital Medicine Faculty

OBJECTIVES

We aimed to decrease barriers to acquiring Point-of-Care Ultrasound (POCUS) knowledge among attending physicians and improve the safety of trainee POCUS use through a novel flexible and cognitive based curriculum.

METHODS

We developed three educational pathways using varied approaches to educational delivery: a novel and asynchronous cognitive curriculum to allow Educational Supervision, a hands-on pathway for Limited Practice, and a more robust pathway for Independent Practice and credentialing.

RESULTS

From November 2018 through June 2021, 102 of 116 hospitalists engaged in some portion of the curriculum. Twenty-four completed the Educational Supervision pathway, 31 completed the Limited Practice pathway, and 17 enrolled in the Independent Practice pathway with three achieving independent practice. Faculty who completed the Educational Supervision pathway had improved scores on a comprehensive POCUS knowledge assessment, 43.5% [95% Confidence Interval (CI) 38.2-48.8] versus 72.0% [95% CI 65.2-78.8], P < .001. Junior faculty were more likely to engage in the supervision pathway and senior faculty were more likely to complete an intensive course to complete the Limited Practice pathway.

CONCLUSIONS

A flexible, cognitive focused POCUS curriculum was effective in creating high levels of engagement, and a cognitive only curriculum resulted in significant improvement in hospitalists' POCUS knowledge without hands on training. Finally, we found that hospitalist engagement in the curriculum did not follow the lowest barrier to entry or time commitment and engagement varied by time in practice. Training faculty to independent practice remains a substantial challenge.

The Effect of a Liberal Approach to Glucose Control in Critically Ill Patients with Type 2 Diabetes: A multicenter, parallel-group, open-label, randomized clinical trial

Rationale Blood glucose concentrations affect outcomes in critically ill patients but the optimal target blood glucose range in those with type 2 diabetes is unknown. Objective To evaluate the effects of a 'liberal' approach to targeted blood glucose range during intensive care unit (ICU) admission. Methods This mutlicenter, parallel-group, open-label, randomized clinical trial included 419 adult patients with type 2 diabetes expected to be in the ICU on at least three consecutive days. In the intervention group intravenous insulin was commenced at a blood glucose >252 mg/dL and titrated to a target range of 180 to 252 mg/dL. In the comparator group insulin was commenced at a blood glucose >180 mg/dL and titrated to a target range of 108 to 180 mg/dL. The primary outcome was incident hypoglycemia (<72 mg/dL). Secondary outcomes included glucose metrics and clinical outcomes. Main Results At least one episode of hypoglycemia occurred in 10 of 210 (5%) patients assigned the intervention and 38 of 209 (18%) patients assigned the comparator (incident rate ratio: 0.21 (95% CI, 0.09 to 0.49); P<0.001). Those assigned the intervention had greater blood glucose concentrations (daily mean, minimum, maximum), less glucose variability and less relative hypoglycaemia (P<0.001 for all comparisons). By day 90, 62 of 210 (29.5%) in the intervention and 52 of 209 (24.9%) in the comparator group had died (absolute difference 4.6 percentage points (95%CI, -3.9 to 13.2%); P=0.29). Conclusions A liberal approach to blood glucose targets reduced incident hypoglycemia but did not improve patient-centered outcomes. Clinical trial registration available at www.anzctr.org.au, ID: ACTRN12616001135404.

The Monitoring with Advanced Sensors, Transmission and E-Resuscitation in Traumatic Brain Injury (MASTER-TBI) collaborative: bringing data science to the ICU bedside

Background: With the adoption of multimodal neuromonitoring techniques, a large amount of high resolution neurophysiological data is generated during the treatment of patients with moderate to severe traumatic brain injury (m-sTBI) that is available for further analysis. The Monitoring with Advanced Sensors, Transmission and E-Resuscitation in Traumatic Brain Injury (MASTER-TBI) collaborative was formed in 2020 to facilitate analysis of these data. Objective: The MASTER-TBI collaborative curates m-sTBI patient data for the purposes of comparative effectiveness research, machine learning algorithm development, and neuropathophysiological phenomena analysis. Design, setting and participants: The MASTER-TBI collaborative is a multicentre longitudinal cohort study which utilises a novel hybrid cloud platform and other data science-informed techniques to collect and analyse data from patients with m-sTBI in whom both intracranial pressure monitoring and ICM+ (Cambridge Enterprise, Cambridge, UK) neuromonitoring software are utilised. MASTER-TBI enrols patients with m-sTBI from three participating Australian trauma intensive care units (ICUs). Main outcome measures: Captured outcome measures available for analysis include pathophysiological events (intracranial hypertension, cerebral perfusion pressure variations etc), surgical interventions, ICU and hospital length of stay, patient discharge status, and, where available, Glasgow Outcome Score-Extended (GOS-E) at 6 months. Results and conclusion: MASTER-TBI continues to develop data science-informed systems and techniques to maximise the use of captured high resolution m-sTBI patient neuromonitoring data. The highly innovative systems provide a world-class platform which aims to enhance the search for improved m-sTBI care and outcomes. This article provides an overview of the MASTER-TBI project's developed systems and techniques as well as a rationale for the approaches taken.

Rethinking PICO in the Machine Learning Era: ML-PICO

BACKGROUND

Machine learning (ML) has captured the attention of many clinicians who may not have formal training in this area but are otherwise increasingly exposed to ML literature that may be relevant to their clinical specialties. ML papers that follow an outcomes-based research format can be assessed using clinical research appraisal frameworks such as PICO (Population, Intervention, Comparison, Outcome). However, the PICO frameworks strain when applied to ML papers that create new ML models, which are akin to diagnostic tests. There is a need for a new framework to help assess such papers.

OBJECTIVE

We propose a new framework to help clinicians systematically read and evaluate medical ML papers whose aim is to create a new ML model: ML-PICO (Machine Learning, Population, Identification, Crosscheck, Outcomes). We describe how the ML-PICO framework can be applied toward appraising literature describing ML models for health care.

CONCLUSION

The relevance of ML to practitioners of clinical medicine is steadily increasing with a growing body of literature. Therefore, it is increasingly important for clinicians to be familiar with how to assess and best utilize these tools. In this paper we have described a practical framework on how to read ML papers that create a new ML model (or diagnostic test): ML-PICO. We hope that this can be used by clinicians to better evaluate the quality and utility of ML papers.

Long-term Survival of Critically Ill Patients Stratified According to Pandemic Triage Categories: A Retrospective Cohort Study

Background

The COVID-19 pandemic has led to unprecedented demand for ICUs, with the need to triage admissions along with the development of ICU triage criteria. However, how these criteria relate to outcomes in patients already admitted to the ICU is unknown, as is the incremental ICU capacity that triage of these patients might create given existing admission practices.

Research Question

What is the short- and long-term survival of low- vs high-priority patients for ICU admission according to current pandemic triage criteria?

Study Design and Methods

This study analyzed prospectively collected registry data (2007-2018) in 23 ICUs in Victoria, Australia, with probabilistic linkage with death registries. After excluding elective surgery, admissions were stratified according to existing ICU triage protocol prioritization as low (age ≥ 85 years, or severe chronic illness, or Sequential Organ Failure Assessment [SOFA] score = 0 or ≥ 12), medium (SOFA score = 8-11) or high (SOFA score = 1-7) priority. The primary outcome was long-term survival. Secondary outcomes were in-hospital mortality, ICU length of stay (LOS) and bed-day usage.

Results

This study examined 126,687 ICU admissions. After 5 years of follow-up, 1,093 of 3,296 (33%; 95% CI, 32-34) of “low-priority” patients aged ≥ 85 years or with severe chronic illness and 86 of 332 (26%; 95% CI, 24-28) with a SOFA score ≥ 12 were still alive. Sixty-three of 290 (22%; 95% CI, 17-27) of patients in these groups followed up for 10 years were still alive. Together, low-priority patients accounted for 27% of all ICU bed-days and had lower in-hospital mortality (22%) than the high-priority patients (28%). Among nonsurvivors, low-priority admissions had shorter ICU LOS than medium- or high-priority admissions.

Interpretation

Current SOFA score or age or severe comorbidity-based ICU pandemic triage protocols exclude patients with a close to 80% hospital survival, a > 30% five-year survival, and 27% of ICU bed-day use. These findings imply the need for stronger evidence-based ICU triage protocols.

A fixed dose approach to thrombosis chemoprophylaxis may be inadequate in heavier critically ill patients

Objectives: Overweight patients are at greater risk of venous thromboembolism. We aimed to describe prescribing patterns of thrombosis chemoprophylaxis in critically ill patients weighing ≥ 100 kg and quantify the effectiveness of these regimens using the surrogate biomarker of plasma anti-Xa level. Design, setting and patients: A prospective single-centre cohort study was conducted over a 6-month period. Patients weighing ≥ 100 kg who were prescribed enoxaparin for chemoprophylaxis and expected to remain in the intensive care unit for > 48 hours were eligible. Anti-Xa levels were measured once a patient had received at least three consecutive doses of enoxaparin. Peak levels were measured 4-6 hours after the third dose and trough levels were measured before the fourth dose. Anti-Xa levels were compared with established target ranges for peak and trough anti-Xa levels (0.2-0.5 IU/mL and > 0.1 IU/mL, respectively). Results: Eighty-eight patients met the eligibility criteria, and anti-Xa levels for 42 patients were obtained. Fixed dose chemoprophylaxis approaches varied considerably, with 40 mg once daily (54/88 [61%]) and 40 mg twice daily (20/88 [23%]) being the most frequently prescribed regimens. No patient had a peak anti-Xa level > 0.5 IU/mL. When comparing 40 mg once daily versus twice daily, the once daily regimen had lower median trough levels (0.01 IU/mL [interquartile range (IQR), 0.00-0.04] v 0.09 IU/mL [IQR, 0.05-0.13]; P < 0.001) and greater proportions of patients with levels below the established range (< 0.1 IU/mL) (15/16 [95%] v 7/14 [50%]; P = 0.002) and levels that were undetectable (0.00 IU/mL) (8/16 [50%] v 1/14 [7%]; P = 0.01). Conclusions: At a single centre, thrombosis chemoprophylaxis prescribing patterns for heavier critically ill patients varied considerably. Current fixed dose approaches may be inadequate in this cohort.

Optimising a targeted test reduction intervention for patients admitted to the intensive care unit: The Targeted Intensive Care Test Ordering Cluster Trial intervention

BACKGROUND

Approaches to routine diagnostic testing in the intensive care unit include time-scheduled testing and targeted testing. Blood tests and chest radiographs requested on a routine, time-scheduled basis may reduce the risk of missing important findings. Targeted testing, considering individual patient needs, may reduce unnecessary testing, wasted clinician time, and costs. However, existing evidence of targeted testing interventions is generally of low quality, and the optimal testing approach is uncertain.

OBJECTIVES

The aim of the study was to describe the development of an intervention to reduce unnecessary diagnostic test ordering by clinicians working in intensive care, with the aim of informing the design of a pivotal clinical trial.

METHODS

The Capability, Opportunity, Motivation-Behaviour model was used as a theoretical framework for change. The intervention components were informed by systematically identifying, assessing, and classifying targeted testing interventions in behavioural terms. Feedback from intensive care clinicians and patients was sought using surveys and a consumer reference group.

RESULTS

The mean percentage of routine tests considered unnecessary by 201 intensive care clinicians was 33 (standard deviation = 16). When presented with a statement of the pros and cons for targeted versus liberal testing (n = 154), 93 (60%) consumer survey respondents preferred a more liberal approach, 33 (21%) preferred a more restrictive approach, and 28 (18%) were unsure. There were 24 behavioural interventions identified and incorporated into the final intervention. This had five major components: (i) a management committee to acquire, disseminate, and coordinate intervention-related information, (ii) a targeted testing guideline for sites, (iii) educational material for sites, (iv) site medical and nursing champions, and (v) site audit and feedback.

CONCLUSIONS

Although surveyed intensive care clinicians report substantial unnecessary routine diagnostic testing, on the basis of currently available evidence, consumers prefer a more liberal approach. This feedback, and a framework to identify behavioural interventions, has been used to inform the design of a proposed targeted testing clinical trial.

Routine Intraoperative Inhaled Milrinone and Iloprost Reduces Inotrope Use in Patients Undergoing Cardiac Surgery: A Retrospective Cohort Pilot Study

BACKGROUND

Catecholamine inotropes are frequently used after cardiopulmonary bypass (CPB) but may have undesirable effects. The aim was to identify whether the routine use of inhaled pulmonary vasodilators might reduce the requirement for inotrope drugs after cardiac surgery.

METHODS

Retrospective cohort study of sequential patients undergoing cardiac surgery at the Royal Melbourne Hospital performed by a single surgeon and anesthesia care team, within 14 months before and after routine implementation of inhaled pulmonary vasodilators, August 2017. Milrinone 4 mg and iloprost 20 µg were inhaled using a vibrating mesh nebulizer (Aerogen) before initiation of CPB and at chest closure. Other aspects of clinical management were unaltered over the time period. Two investigators blinded to each other extracted data from electronic and written medical records. The primary outcome was any use of inotropes in the perioperative period; a Fisher exact test was used to analyze any differences between the 2 groups. Demographic data, hemodynamic data, and use of inotropes and vasopressors were collected from induction of anesthesia to 36 hours postoperative in the intensive care unit (ICU). Hospital and ICU length of stay, cost, and complications were collected.

RESULTS

Any use of inotropes was significantly lower with inhaled pulmonary dilators (62.5% vs 86.8%, odds ratio [95% confidence interval {CI}], 0.253 (0.083-0.764); P = .011), including intraoperative inotrope use (37.5% vs 86.8%, odds ratio [95% CI], 0.091 (0.03-0.275); P < .001). ICU length of stay was significantly lower with inhaled pulmonary dilators (45 hours, interquartile range [IQR], 27-65 vs 50 hours, IQR, 45-74; P = .026). There were no significant differences among major postoperative complications or costs between groups.

CONCLUSIONS

Routine use of inhaled milrinone 4 mg and iloprost 20 µg before and after CPB is associated with reduced postoperative inotrope use.

Study protocol and statistical analysis plan for the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial

BACKGROUND

Contemporary glucose management of intensive care unit (ICU) patients with type 2 diabetes is based on trial data derived predominantly from patients without type 2 diabetes. This is despite the recognition that patients with type 2 diabetes may be relatively more tolerant of hyperglycaemia and more susceptible to hypoglycaemia. It is uncertain whether glucose targets should be more liberal in patients with type 2 diabetes.

OBJECTIVE

To detail the protocol, analysis and reporting plans for a randomised clinical trial - the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial - which will evaluate the risks and benefits of targeting a higher blood glucose range in patients with type 2 diabetes.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTION

A multicentre, parallel group, open label phase 2B randomised controlled clinical trial of 450 critically ill patients with type 2 diabetes. Patients will be randomised 1:1 to liberal blood glucose (target 10.0-14.0 mmol/L) or usual care (target 6.0-10.0 mmol/L).

MAIN OUTCOME MEASURES

The primary endpoint is incident hypoglycaemia (< 4.0 mmol/L) during the study intervention. Secondary endpoints include biochemical and feasibility outcomes.

RESULTS AND CONCLUSION

The study protocol and statistical analysis plan described will delineate conduct and analysis of the trial, such that analytical and reporting bias are minimised.

TRIAL REGISTRATION

This trial has been registered on the Australian New Zealand Clinical Trials Registry (ACTRN No. 12616001135404) and has been endorsed by the Australian and New Zealand Intensive Care Society Clinical Trials Group.

Study protocol and statistical analysis plan for the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial

BACKGROUND: Contemporary glucose management of intensive care unit (ICU) patients with type 2 diabetes is based on trial data derived predominantly from patients without type 2 diabetes. This is despite the recognition that patients with type 2 diabetes may be relatively more tolerant of hyperglycaemia and more susceptible to hypoglycaemia. It is uncertain whether glucose targets should be more liberal in patients with type 2 diabetes. OBJECTIVE: To detail the protocol, analysis and reporting plans for a randomised clinical trial — the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial — which will evaluate the risks and benefits of targeting a higher blood glucose range in patients with type 2 diabetes. DESIGN, SETTING, PARTICIPANTS AND INTERVENTION: A multicentre, parallel group, open label phase 2B randomised controlled clinical trial of 450 critically ill patients with type 2 diabetes. Patients will be randomised 1:1 to liberal blood glucose (target 10.0–14.0 mmol/L) or usual care (target 6.0–10.0 mmol/L). MAIN OUTCOME MEASURES: The primary endpoint is incident hypoglycaemia (< 4.0 mmol/L) during the study intervention. Secondary endpoints include biochemical and feasibility outcomes. RESULTS AND CONCLUSION: The study protocol and statistical analysis plan described will delineate conduct and analysis of the trial, such that analytical and reporting bias are minimised. TRIAL REGISTRATION: This trial has been registered on the Australian New Zealand Clinical Trials Registry (ACTRN No. 12616001135404) and has been endorsed by the Australian and New Zealand Intensive Care Society Clinical Trials Group.

Prevention of pathogen transmission during ultrasound use in the Intensive Care Unit: Recommendations from the College of Intensive Care Medicine Ultrasound Special Interest Group (USIG)

ICU ultrasonography constitutes important part of modern car patient care. Current standards and practice of infection control and prevention are inadequate. This purpose of this document is to adapt and expand the 2017 Australasian Society for Ultrasound in Medicine (ASUM) and the Australasian College for Infection Prevention Control (ACIPC) guidelines on minimum standards for reprocessing/cleaning of ultrasound transducers to the specifics of intensive care medicine and provide advice to the ICU practitioners and health care administrators. It considers the medical, administrative, financial and practical controversies surrounding implementation, and addresses emerging issues of care for patients with confirmed or suspected Corona Virus Disease 2019 (COVID-19).

COVID-US: A simplified approach to cardiopulmonary ultrasound in suspected and confirmed COVID-19 patients in surge crisis

The severe acute respiratory syndrome coronavirus 2 (COVID-19) pandemic has placed an unprecedented challenge on healthcare systems across the globe. Rapid assessment of the cardiorespiratory function to monitor disease progression and guide treatment is essential. Therefore, we have designed the COVID-US: a simplified cardiopulmonary ultrasound approach to use in suspected and confirmed COVID-19 patients, to aid front-line health workers in their decision-making in a surge crisis.

Early hypoalbuminemia is associated with 28-day mortality in severely burned patients: A retrospective cohort study

BACKGROUND

Hypoalbuminemia is a frequent condition in the first 24 h after a severe burn injury and is associated with worse outcomes.

METHODOLOGY

We investigated the relation between very early hypoalbuminemia (<6 h after admission) and clinical outcome in a retrospective cohort admitted to our unit for severe burn injuries between 2012 and 2017.

RESULTS

73 severely burned patients were included, with a delay of admission of 3 (2-4) h. In a context of early exogenous supply of albumin, admission and 4H Albuminemia (Alb4 h) were significantly lower in deceased patients (respectively, 34 (29-37) vs 27 (23-30) g/l; p = 0.009 and 27 (24-32) vs 21 (17-27) g/l; p = 0.022) whereas albuminemia ≥6 h were not. The best threshold value of Alb4 h to discriminate 28-day mortality was 23 g/l. Patients with an Alb4 h < 23 g/l had a higher 28-day mortality than patients with an Alb4 h ≥ 23 g/l (42% vs 11%; p = 0.003); adjusted OR = 4.47 (95% CI 1.15-17.36); p = 0.03.

CONCLUSION

In severely burned patients receiving early albumin supply, early hypoalbuminemia is associated with higher mortality whereas later albuminemia (≥6 h) is not. Exploration of whether early albumin infusion (8-12 h post injury) may alter clinical outcome is warranted.

"Likely overassistance" during invasive pressure support ventilation in patients in the intensive care unit: a multicentre prospective observational study

OBJECTIVE

To evaluate the prevalence of "likely overassistance" (categorised by respiratory rate [RR] ≤ 17 breaths/min or rapid shallow breathing index [RSBI] ≤ 37 breaths/min/L) during invasive pressure support ventilation (PSV), and the additional prevalence of fixed ventilator settings.

DESIGN

Multicentre prospective observational study of invasive PSV practice in six general Victorian intensive care units with blinding of staff members to data collection.

PATIENTS

At each hospital, investigators collected data between 11 am and 2 pm on all invasive PSV-treated patients on 60 sequential days, excluding weekends and public holidays, between 22 February and 30 August 2017. Each patient was included for maximum of 3 days.

MAIN RESULTS

We studied 231 patients, with a total of 379 observations episodes over the study period. There were 131 patients (56.7%) with at least one episode of RR ≤ 17 breaths/min; 146 patients (63.2%) with at least one episode of RSBI ≤ 37 breaths/min/L, and 85 patients (36.8%) with at least one episode of combined RR ≤ 17 breaths/min and RSBI ≤ 37 breaths/min/L. Moreover, the total number of observations with "likely overassistance" (RR ≤ 17 or RSBI ≤ 37 breaths/min/L) was 178 (47%) and 204 (53.8%), respectively; while for both combined criteria, it was 154 (40.6%). We also found that 10 cmH²O pressure support was delivered on 210 of the observations (55.4%) and adjusted in less than 25% of observations. Finally, less than half (179 observations) of all PSV-delivered tidal volumes (V_T) were at the recommended value of 6-8 mL/kg predicted body weight (PBW) and more than 20% (79 observations) were at ≥ 10 mL/kg PBW.

CONCLUSION

In a cohort of Victorian hospitals in Australia, during invasive PSV, "likely overassistance" was common, and the pressure support level was delivered in a standardised and unadjusted manner at 10 cmH²O, resulting in the frequent delivery of potentially injurious V_T.

Outcome and potentially modifiable risk factors for candidemia in critically ill burns patients: A matched cohort study

BACKGROUND

Patients with extensive burns are at risk of developing candidemia.

OBJECTIVES

To identify potentially modifiable risk factors and outcomes of candidemia in critically ill burns patients.

PATIENTS AND METHODS

Retrospective matched cohort study including adult burns patients. Patients who developed candidemia were matched with burns patients with Candida spp colonisation and sepsis or septic shock without candidemia in a ratio of 1:3 (same severity scores and colonisation index). Univariate and multiple regression analyses were performed.

RESULTS

Of 130 severely burned patients with Candida spp colonisation and at least one episode of sepsis or septic shock, 14 were diagnosed with candidemia. In the candidemia group, patients had a median (IQR) total burns surface area (TBSA) of 57 (38-68)%, SAPSII of 43 (36-58) and ABSI of 11 (8-13). Multiple regression analysis showed that only duration of prior antibiotic therapy was independently associated with candidemia. ICU mortality was higher in the candidemia group (71% vs 35% [P = 0.02]). The log-rank test for 28-day mortality comparing patients with candidemia treated with an empirical strategy vs a curative strategy did not reach significance (P = 0.056).

CONCLUSIONS

Burns patients having received recent antibiotherapy have a higher risk of candidemia. Antifungal strategies did not influence outcome in this series.

Opinions and practices of blood glucose control in critically ill patients with pre-existing type 2 diabetes in Australian and New Zealand intensive care units

BACKGROUND

Approximately 9000 patients with type-2 diabetes mellitus (T2DM) are admitted to an intensive care unit (ICU) in Australia and New Zealand annually. For these patients, recent exploratory data suggest that targeting a more liberal blood glucose range during ICU admission may be safe and potentially beneficial. However, the current approach to blood glucose management of patients with T2DM in Australia and New Zealand ICUs is not well described, and there is uncertainty about clinician equipoise for trials of liberal glycaemic control in these patients.

AIM

The aim is to describe self-reported blood glucose management in patients with T2DM by intensivists working in Australian and New Zealand ICUs and to establish whether equipoise exists for a trial of liberal versus standard glycaemic control in such patients.

METHOD

An online questionnaire of Australia and New Zealand intensivists conducted in July-September 2016.

RESULTS

Seventy-one intensivists responded. Forty-five (63%) used a basic nomogram to titrate insulin. Sixty-six (93%) reported that insulin was commenced at blood glucose concentrations >10 mmol/L and titrated to achieve a blood glucose concentration between 6.0 and 10.0 mmol/L. A majority of respondents (75%) indicated that there was insufficient evidence to define optimal blood glucose targets in patients with T2DM, and 59 (83%) were prepared to enrol such patients in a clinical trial to evaluate a more liberal approach.

CONCLUSION

A majority of respondents were uncertain about the optimal blood glucose target range for patients with T2DM and would enrol such patients in a comparative trial of conventional versus liberal blood glucose control.

Dependence of Present and Future European Temperature Extremes on the Location of Atmospheric Blocking

The impact of atmospheric blocking on European heat waves (HWs) and cold spells (CSs) is investigated for present and future conditions . A 50-member ensemble of the second generation Canadian Earth System Model is used to quantify the role of internal variability in the response to blocking. We find that the present blocking-extreme temperature link is well represented compared to ERA-Interim, despite a significant underestimation of blocking frequency in most ensemble members. Our results show a strong correlation of blocking with northern European HWs in summer, spring, and fall. However, we also find a strong anticorrelation between blocking and HW occurrence in southern Europe in all seasons. Blocking increases the CS frequency particularly in southern Europe in fall, winter, and spring but reduces it in summer. For the future we find that blocking will continue to play an important role in the development of both CSs and HWs in all seasons.

101 Dispelling the curse: improvement of ventilatory drive in central alveolar hypoventilation syndrome after medullary infarction

Introduction

Central alveolar hypoventilation syndrome (CAHS) is a rare complication of stroke affecting the medullary respiratory centre. CAHS is characterised by impaired ventilatory response to CO2 leading to hypoventilation, hyper-capnoea and coma. Experimental studies have linked this syndrome to areas in the dorsal and ventrolateral medulla. CAHS is associated with long-term invasive ventilatory support, high mortality and morbidity. It is unclear whether sensitivity to CO2 can improve after the initial ischaemic medullary insult.

Case

A 78 year old woman presenting with CAHS secondary to a unilateral left posterior inferior cerebellar artery infarction. MRI images confirmed that dorsal and ventrolateral medullary areas were affected. The patient was intubated initially for hyper-capnoeic respiratory failure and required a tracheostomy for ongoing respiratory support. To assess progress of respiratory recovery, we measured the patient’s ventilatory response to PaCO2 at 5, 7, and 14 days of admission. Parameters recorded included PaO2, ETCO2, PaCO2, pH, respiratory rate, and minute ventilation. During this time the patient underwent progressive periods of unsupported ventilation with close monitoring. Statistical correlation between respiratory rate and CO2 was measured by Pearson’s correlation coefficient (R). Her RR initially did not increase with PaCO2 during spontaneous ventilation (R=0.2604 p=0.077). Apnoeic episodes were frequent up to 41 episodes per 30 min of observation lasting up to 30 s. On day 7(R=0.7203 p<0.05) and up to day 14 (R=0.6295 p<0.05), there was a progressive statistically significant improvement in positive correlation between PCO2 and respiratory rate. This was associated with a reduction in apnoeic episodes possibly reflecting a recovery in ventilatory drive.

Conclusion

This is the first detailed report demonstrating spontaneous recovery in CO2 responsiveness in the setting of CAHS secondary to unilateral medullary stroke. Plasticity of structures such as the retro-trapezoid nucleus are likely to play a role in recovery of CO2 sensitivity.

References

. Harper, et al. Functional neuroanatomy and sleep-disordered breathing: implications for autonomic regulation. Anatomical record2012;295(9):1385–95.

. Mishina, et al. Efficacy of tracheostomy for central alveolar hypoventilation syndrome caused by lateral medullary infarction. Journal of Nippon Medical School2014;81(4):276–84.

Potentially modifiable respiratory variables contributing to outcome in ICU patients without ARDS: a secondary analysis of PRoVENT

BACKGROUND

The majority of critically ill patients do not suffer from acute respiratory distress syndrome (ARDS). To improve the treatment of these patients, we aimed to identify potentially modifiable factors associated with outcome of these patients.

METHODS

The PRoVENT was an international, multicenter, prospective cohort study of consecutive patients under invasive mechanical ventilatory support. A predefined secondary analysis was to examine factors associated with mortality. The primary endpoint was all-cause in-hospital mortality.

RESULTS

935 Patients were included. In-hospital mortality was 21%. Compared to patients who died, patients who survived had a lower risk of ARDS according to the 'Lung Injury Prediction Score' and received lower maximum airway pressure (P_max), driving pressure (ΔP), positive end-expiratory pressure, and FiO₂ levels. Tidal volume size was similar between the groups. Higher P_max was a potentially modifiable ventilatory variable associated with in-hospital mortality in multivariable analyses. ΔP was not independently associated with in-hospital mortality, but reliable values for ΔP were available for 343 patients only. Non-modifiable factors associated with in-hospital mortality were older age, presence of immunosuppression, higher non-pulmonary sequential organ failure assessment scores, lower pulse oximetry readings, higher heart rates, and functional dependence.

CONCLUSIONS

Higher P_max was independently associated with higher in-hospital mortality in mechanically ventilated critically ill patients under mechanical ventilatory support for reasons other than ARDS. Trial Registration ClinicalTrials.gov (NCT01868321).

Epidemiological characteristics, practice of ventilation, and clinical outcome in patients at risk of acute respiratory distress syndrome in intensive care units from 16 countries (PRoVENT): an international, multicentre, prospective study

BACKGROUND

Scant information exists about the epidemiological characteristics and outcome of patients in the intensive care unit (ICU) at risk of acute respiratory distress syndrome (ARDS) and how ventilation is managed in these individuals. We aimed to establish the epidemiological characteristics of patients at risk of ARDS, describe ventilation management in this population, and assess outcomes compared with people at no risk of ARDS.

METHODS

PRoVENT (PRactice of VENTilation in critically ill patients without ARDS at onset of ventilation) is an international, multicentre, prospective study undertaken at 119 ICUs in 16 countries worldwide. All patients aged 18 years or older who were receiving mechanical ventilation in participating ICUs during a 1-week period between January, 2014, and January, 2015, were enrolled into the study. The Lung Injury Prediction Score (LIPS) was used to stratify risk of ARDS, with a score of 4 or higher defining those at risk of ARDS. The primary outcome was the proportion of patients at risk of ARDS. Secondary outcomes included ventilatory management (including tidal volume [V_T] expressed as mL/kg predicted bodyweight [PBW], and positive end-expiratory pressure [PEEP] expressed as cm H₂O), development of pulmonary complications, and clinical outcomes. The PRoVENT study is registered at ClinicalTrials.gov, NCT01868321. The study has been completed.

FINDINGS

Of 3023 patients screened for the study, 935 individuals fulfilled the inclusion criteria. Of these critically ill patients, 282 were at risk of ARDS (30%, 95% CI 27-33), representing 0·14 cases per ICU bed over a 1-week period. V_T was similar for patients at risk and not at risk of ARDS (median 7·6 mL/kg PBW [IQR 6·7-9·1] vs 7·9 mL/kg PBW [6·8-9·1]; p=0·346). PEEP was higher in patients at risk of ARDS compared with those not at risk (median 6·0 cm H₂O [IQR 5·0-8·0] vs 5·0 cm H₂O [5·0-7·0]; p<0·0001). The prevalence of ARDS in patients at risk of ARDS was higher than in individuals not at risk of ARDS (19/260 [7%] vs 17/556 [3%]; p=0·004). Compared with individuals not at risk of ARDS, patients at risk of ARDS had higher in-hospital mortality (86/543 [16%] vs 74/232 [32%]; p<0·0001), ICU mortality (62/533 [12%] vs 66/227 [29%]; p<0·0001), and 90-day mortality (109/653 [17%] vs 88/282 [31%]; p<0·0001). V_T did not differ between patients who did and did not develop ARDS (p=0·471 for those at risk of ARDS; p=0·323 for those not at risk).

INTERPRETATION

Around a third of patients receiving mechanical ventilation in the ICU were at risk of ARDS. Pulmonary complications occur frequently in patients at risk of ARDS and their clinical outcome is worse compared with those not at risk of ARDS. There is potential for improvement in the management of patients without ARDS. Further refinements are needed for prediction of ARDS.

FUNDING

None.

Clinical outcomes of adult inpatients treated with continuous subcutaneous insulin infusion for diabetes mellitus: a systematic review

AIMS

To provide a systematic review of the current evidence concerning the diabetes-related outcomes of patients provided with continuous subcutaneous insulin infusion for treating diabetes mellitus while a hospital inpatient.

METHODS

Relevant publications were obtained from MEDLINE and EMBASE databases concerning hospital inpatients with diabetes being treated with continuous subcutaneous insulin infusion. Studies were assessed independently by two reviewers, and data on the following outcomes were extracted: inpatient mortality; clinical complications, e.g. diabetic ketoacidosis; hyperglycaemia; hypoglycaemia; length of hospital stay; mean bedside glucose level; and glucose level on discharge. Obstetric cases were examined separately to look at maternal and neonatal glycaemic outcomes.

RESULTS

A total of 11 studies met the required criteria and were analysed in detail, 5 of which were predominantly obstetric. No significant complications were reported, with no incidences of death, ketoacidosis or severe hypoglycaemia. Length of hospital stay appeared to be shorter in those patients who remained on continuous subcutaneous insulin infusion, while data on mild hyperglycaemia and hypoglycaemia were inconclusive.

CONCLUSIONS

There are limited data available to form a significant conclusion about the safety of continuous subcutaneous insulin infusion continuation in hospital; however, its use can be justified with the presence of a specialized inpatient diabetes team for advice and support and an alternative treatment regime (e.g. subcutaneous basal bolus) should be accessible if the need were to arise.

Endothelium and Regulatory Inflammatory Mechanisms During Organ Rejection

Endothelial integrity is mandatory for physiologic organ function; however, endothelium dysfunction can be caused by systemic inflammation, occurring during sepsis or organ rejection after transplantation. This article will address our current understanding of endothelial involvement in organ transplantation and rejection. Overall, more detailed studies focusing on the endothelial modulation after organ transplantation would be necessary to investigate the role of endothelium activation during organ rejection.