Critical Care - Research Publications

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    A fixed dose approach to thrombosis chemoprophylaxis may be inadequate in heavier critically ill patients
    Yi, G ; Deane, AM ; Ankrays, M ; Sharrock, L ; Anstey, J ; Abdelhamid, YA (AUSTRALASIAN MED PUBL CO LTD, 2021-03)
    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.
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    Mild Hypercapnia or Normocapnia after Out-of-Hospital Cardiac Arrest
    Eastwood, G ; Nichol, AD ; Hodgson, C ; Parke, RL ; McGuinness, S ; Nielsen, N ; Bernard, S ; Skrifvars, MB ; Stub, D ; Taccone, FS ; Archer, J ; Kutsogiannis, D ; Dankiewicz, J ; Lilja, G ; Cronberg, T ; Kirkegaard, H ; Capellier, G ; Landoni, G ; Horn, J ; Olasveengen, T ; Arabi, Y ; Chia, YW ; Markota, A ; Haenggi, M ; Wise, MP ; Grejs, AM ; Christensen, S ; Munk-Andersen, H ; Granfeldt, A ; Andersen, GO ; Qvigstad, E ; Flaa, A ; Thomas, M ; Sweet, K ; Bewley, J ; Backlund, M ; Tiainen, M ; Iten, M ; Levis, A ; Peck, L ; Walsham, J ; Deane, A ; Ghosh, A ; Annoni, F ; Chen, Y ; Knight, D ; Lesona, E ; Tlayjeh, H ; Svensek, F ; McGuigan, PJ ; Cole, J ; Pogson, D ; Hilty, MP ; During, JP ; Bailey, MJ ; Paul, E ; Ady, B ; Ainscough, K ; Hunt, A ; Monahan, S ; Trapani, T ; Fahey, C ; Bellomo, R (MASSACHUSETTS MEDICAL SOC, 2023-07-06)
    BACKGROUND: Guidelines recommend normocapnia for adults with coma who are resuscitated after out-of-hospital cardiac arrest. However, mild hypercapnia increases cerebral blood flow and may improve neurologic outcomes. METHODS: We randomly assigned adults with coma who had been resuscitated after out-of-hospital cardiac arrest of presumed cardiac or unknown cause and admitted to the intensive care unit (ICU) in a 1:1 ratio to either 24 hours of mild hypercapnia (target partial pressure of arterial carbon dioxide [Paco2], 50 to 55 mm Hg) or normocapnia (target Paco2, 35 to 45 mm Hg). The primary outcome was a favorable neurologic outcome, defined as a score of 5 (indicating lower moderate disability) or higher, as assessed with the use of the Glasgow Outcome Scale-Extended (range, 1 [death] to 8, with higher scores indicating better neurologic outcome) at 6 months. Secondary outcomes included death within 6 months. RESULTS: A total of 1700 patients from 63 ICUs in 17 countries were recruited, with 847 patients assigned to targeted mild hypercapnia and 853 to targeted normocapnia. A favorable neurologic outcome at 6 months occurred in 332 of 764 patients (43.5%) in the mild hypercapnia group and in 350 of 784 (44.6%) in the normocapnia group (relative risk, 0.98; 95% confidence interval [CI], 0.87 to 1.11; P = 0.76). Death within 6 months after randomization occurred in 393 of 816 patients (48.2%) in the mild hypercapnia group and in 382 of 832 (45.9%) in the normocapnia group (relative risk, 1.05; 95% CI, 0.94 to 1.16). The incidence of adverse events did not differ significantly between groups. CONCLUSIONS: In patients with coma who were resuscitated after out-of-hospital cardiac arrest, targeted mild hypercapnia did not lead to better neurologic outcomes at 6 months than targeted normocapnia. (Funded by the National Health and Medical Research Council of Australia and others; TAME ClinicalTrials.gov number, NCT03114033.).
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    A multicentre point prevalence study of delirium assessment and management in patients admitted to Australian and New Zealand intensive care units
    Ankravs, MJ ; Udy, AA ; Byrne, K ; Knowles, S ; Hammond, N ; Saxena, MK ; Reade, MC ; Bailey, M ; Bellomo, R ; Deane, AM (AUSTRALASIAN MED PUBL CO LTD, 2020-12)
    Objective: To characterise the assessment and management of delirium in patients admitted to intensive care units (ICUs) in Australia and New Zealand. Methods: We conducted a multicentre observational point prevalence study across 44 adult Australian and New Zealand ICUs. Data were extracted for all patients in the ICU in terms of assessment and treatment of delirium. ICU-level data were collected regarding the use of explicit protocols related to delirium. Results: We studied 627 patients, with 54% (336/627) having at least one delirium screening assessment performed. The Confusion Assessment Method for the ICU (CAM-ICU) was the most frequently used tool (88%, 296/336). Of patients assessed, 20% (68) were identified to have delirium. Eighteen per cent (111) of patients were administered a drug to manage delirium, with 41% (46) of those receiving a drug having no recorded assessment for delirium on that day. Of the drugs used to treat delirium, quetiapine was the most frequently administered. Physical restraints were applied to 8% (48/626) of patients, but only 17% (8/48) of such patients had been diagnosed with delirium. Most physically restrained patients either did not have delirium diagnosed (31%, 15/48) or had no formal assessment recorded (52%, 25/48) on that day. Conclusions: On the study day, more than 50% of patients had a delirium screening assessment performed, with 20% of screened patients deemed to have delirium. Drugs that are prescribed to treat delirium and physical restraints were frequently used in the absence of delirium or the formal assessment for its presence.
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    Study protocol and statistical analysis plan for the Liberal Glucose Control in Critically Ill Patients with Pre-existing Type 2 Diabetes (LUCID) trial
    Poole, AP ; Finnis, ME ; Anstey, J ; Bellomo, R ; Bihari, S ; Biradar, V ; Doherty, S ; Eastwood, G ; Finfer, S ; French, CJ ; Ghosh, A ; Heller, S ; Horowitz, M ; Kar, P ; Kruger, PS ; Maiden, MJ ; Martensson, J ; McArthur, CJ ; McGuinness, SP ; Secombe, PJ ; Tobin, AE ; Udy, AA ; Young, PJ ; Deane, AM (AUSTRALASIAN MED PUBL CO LTD, 2020-06)
    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.
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    Effects of Standard vs Energy-Dense Formulae on Gastric Retention, Energy Delivery, and Glycemia in Critically Ill Patients
    Chapple, L-AS ; Summers, MJ ; Weinel, LM ; Abdelhamid, YA ; Kar, P ; Hatzinikolas, S ; Calnan, D ; Bills, M ; Lange, K ; Poole, A ; O'Connor, SN ; Horowitz, M ; Jones, KL ; Deane, AM ; Chapman, MJ (WILEY, 2021-05)
    BACKGROUND: Energy-dense formulae are often provided to critically ill patients with enteral feed intolerance with the aim of increasing energy delivery, yet the effect on gastric emptying is unknown. The rate of gastric emptying of a standard compared with an energy-dense formula was quantified in critically ill patients. METHODS: Mechanically ventilated adults were randomized to receive radiolabeled intragastric infusions of 200 mL standard (1 kcal/mL) or 100 mL energy-dense (2 kcal/mL) enteral formulae on consecutive days in this noninferiority, blinded, crossover trial. The primary outcome was scintigraphic measurement of gastric retention (percentage at 120 minutes). Other measures included area under the curve (AUC) for gastric retention and intestinal energy delivery (calculated from gastric retention of formulae over time), blood glucose (peak and AUC), and intestinal glucose absorption (using 3-O-methyl-D-gluco-pyranose [3-OMG] concentrations). Comparisons were undertaken using paired mixed-effects models. Data presented are mean ± SE. RESULTS: Eighteen patients were studied (male/female, 14:4; age, 55.2 ± 5.3 years). Gastric retention at 120 minutes was greater with the energy-dense formula (standard, 17.0 ± 5.9 vs energy-dense, 32.5 ± 7.1; difference, 12.7% [90% confidence interval, 0.8%-30.1%]). Energy delivery (AUC120 , 13,038 ± 1119 vs 9763 ± 1346 kcal/120 minutes; P = 0.057), glucose control (peak glucose, 10.1 ± 0.3 vs 9.7 ± 0.3 mmol/L, P = 0.362; and glucose AUC120 8.7 ± 0.3 vs 8.5 ± 0.3 mmol/L.120 minutes, P = 0.661), and absorption (3-OMG AUC120 , 38.5 ± 4.0 vs 35.7 ± 4.0 mmol/L.120 minutes; P = .508) were not improved with the energy-dense formula. CONCLUSION: In critical illness, administration of an energy-dense formula does not reduce gastric retention, increase energy delivery to the small intestine, or improve glucose absorption or glucose control; instead, there is a signal for delayed gastric emptying.
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    Study protocol for TARGET protein: The effect of augmented administration of enteral protein to critically ill adults on clinical outcomes: A cluster randomised, cross-sectional, double cross-over, clinical trial
    Summers, MJ ; Chapple, L-AS ; Bellomo, R ; Chapman, MJ ; Ferrie, S ; Finnis, ME ; French, C ; Hurford, S ; Kakho, N ; Karahalios, A ; Maiden, MJ ; O'Connor, SN ; Peake, SL ; Presneill, JJ ; Ridley, EJ ; Tran-Duy, A ; Williams, PJ ; Young, PJ ; Zaloumis, S ; Deane, AM (ELSEVIER, 2023-09)
    BACKGROUND: It is unknown whether increasing dietary protein to 1.2-2.0 g/kg/day as recommended in international guidelines compared to current practice improves outcomes in intensive care unit (ICU) patients. The TARGET Protein trial will evaluate this. OBJECTIVE: To describe the study protocol for the TARGET Protein trial. DESIGN SETTING AND PARTICIPANTS: TARGET Protein is a cluster randomised, cross-sectional, double cross-over, pragmatic clinical trial undertaken in eight ICUs in Australia and New Zealand. Each ICU will be randomised to use one of two trial enteral formulae for three months before crossing over to the other formula, which is then repeated, with enrolment continuing at each ICU for 12 months. All patients aged ≥16 years in their index ICU admission commencing enteral nutrition will be eligible for inclusion. Eligible patients will receive the trial enteral formula to which their ICU is allocated. The two trial enteral formulae are isocaloric with a difference in protein dose: intervention 100g/1000 ml and comparator 63g/1000 ml. Staggered recruitment commenced in May 2022. MAIN OUTCOMES MEASURES: The primary outcome is days free of the index hospital and alive at day 90. Secondary outcomes include days free of the index hospital at day 90 in survivors, alive at day 90, duration of invasive ventilation, ICU and hospital length of stay, incidence of tracheostomy insertion, renal replacement therapy, and discharge destination. CONCLUSION: TARGET Protein aims to determine whether augmented enteral protein delivery reduces days free of the index hospital and alive at day 90. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ACTRN12621001484831).
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    Administration of pharmacological sleep aids prior to, during and following critical illness
    Wong, C ; Ho, J ; Ankravs, MJ ; Sharrock, L ; Kee, K ; Goldin, J ; MacIsaac, C ; Presneill, JJ ; Abdelhamid, YA ; Deane, AM (WILEY, 2022-11)
    BACKGROUND: Sleep in the intensive care unit (ICU) is frequently disturbed and this may have a detrimental effect on recovery. AIM: To determine the use of pharmacological sleep aids in critically ill patients prior to, during and after ICU admission. METHODS: We conducted a single-centre period prevalence study of all adult patients admitted to a university-associated adult medical-surgical ICU for more than two nights in a 3-month period ending September 2019. The major outcome of interest was the proportion of ICU patients who had a pharmacological sleep aid administered prior to, during and after ICU admission. Associations of selected patient variables with sleep aid prescription in the ICU were summarised both as unadjusted univariable comparisons and as adjusted effect estimates returned by a multivariable logistic regression model. RESULTS: During the study period, 370 patients met all eligibility criteria. A pharmacological sleep aid was identified prior to hospital admission in 34 (9%) patients and in 62 (17%) patients during ICU admission. Of the 340 ICU survivors, 292 remained in the same hospital. Of these, 96 (33%) received a pharmacological sleep aid at least once during their post-ICU general hospital ward stay. Pre-hospital sleep aid use, male sex, longer ICU admission and higher APACHE (Acute Physiology and Chronic Health Evaluation) III scores were associated with sleep aid prescription in the ICU. CONCLUSIONS: Pharmacological sleep aids are administered frequently in the ICU with administration increasing substantially after ICU discharge.
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    Machine learning predicts the short-term requirement for invasive ventilation among Australian critically ill COVID-19 patients
    Karri, R ; Chen, Y-PP ; Burrell, AJC ; Penny-Dimri, JC ; Broadley, T ; Trapani, T ; Deane, AM ; Udy, AA ; Plummer, MP ; Rashid, TA (PUBLIC LIBRARY SCIENCE, 2022-10-26)
    OBJECTIVE(S): To use machine learning (ML) to predict short-term requirements for invasive ventilation in patients with COVID-19 admitted to Australian intensive care units (ICUs). DESIGN: A machine learning study within a national ICU COVID-19 registry in Australia. PARTICIPANTS: Adult patients who were spontaneously breathing and admitted to participating ICUs with laboratory-confirmed COVID-19 from 20 February 2020 to 7 March 2021. Patients intubated on day one of their ICU admission were excluded. MAIN OUTCOME MEASURES: Six machine learning models predicted the requirement for invasive ventilation by day three of ICU admission from variables recorded on the first calendar day of ICU admission; (1) random forest classifier (RF), (2) decision tree classifier (DT), (3) logistic regression (LR), (4) K neighbours classifier (KNN), (5) support vector machine (SVM), and (6) gradient boosted machine (GBM). Cross-validation was used to assess the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of machine learning models. RESULTS: 300 ICU admissions collected from 53 ICUs across Australia were included. The median [IQR] age of patients was 59 [50-69] years, 109 (36%) were female and 60 (20%) required invasive ventilation on day two or three. Random forest and Gradient boosted machine were the best performing algorithms, achieving mean (SD) AUCs of 0.69 (0.06) and 0.68 (0.07), and mean sensitivities of 77 (19%) and 81 (17%), respectively. CONCLUSION: Machine learning can be used to predict subsequent ventilation in patients with COVID-19 who were spontaneously breathing and admitted to Australian ICUs.
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    Muscle Protein Synthesis after Protein Administration in Critical Illness
    Chapple, L-AS ; Kouw, IWK ; Summers, MJ ; Weinel, LM ; Gluck, S ; Raith, E ; Slobodian, P ; Soenen, S ; Deane, AM ; van Loon, LJC ; Chapman, MJ (AMER THORACIC SOC, 2022-09-15)
    Rationale: Dietary protein may attenuate the muscle atrophy experienced by patients in the ICU, yet protein handling is poorly understood. Objectives: To quantify protein digestion and amino acid absorption and fasting and postprandial myofibrillar protein synthesis during critical illness. Methods: Fifteen mechanically ventilated adults (12 male; aged 50 ± 17 yr; body mass index, 27 ± 5 kg⋅m-2) and 10 healthy control subjects (6 male; 54 ± 23 yr; body mass index, 27 ± 4 kg⋅m-2) received a primed intravenous L-[ring-2H5]-phenylalanine, L-[3,5-2H2]-tyrosine, and L-[1-13C]-leucine infusion over 9.5 hours and a duodenal bolus of intrinsically labeled (L-[1-13C]-phenylalanine and L-[1-13C]-leucine) intact milk protein (20 g protein) over 60 minutes. Arterial blood and muscle samples were taken at baseline (fasting) and for 6 hours following duodenal protein administration. Data are mean ± SD, analyzed with two-way repeated measures ANOVA and independent samples t test. Measurements and Main Results: Fasting myofibrillar protein synthesis rates did not differ between ICU patients and healthy control subjects (0.023 ± 0.013% h-1 vs. 0.034 ± 0.016% h-1; P = 0.077). After protein administration, plasma amino acid availability did not differ between groups (ICU patients, 54.2 ± 9.1%, vs. healthy control subjects, 61.8 ± 13.1%; P =  0.12), and myofibrillar protein synthesis rates increased in both groups (0.028 ± 0.010% h-1 vs. 0.043 ± 0.018% h-1; main time effect P = 0.046; P-interaction = 0.584) with lower rates in ICU patients than in healthy control subjects (main group effect P = 0.001). Incorporation of protein-derived phenylalanine into myofibrillar protein was ∼60% lower in ICU patients (0.007 ± 0.007 mol percent excess vs. 0.017 ± 0.009 mol percent excess; P = 0.007). Conclusions: The capacity for critically ill patients to use ingested protein for muscle protein synthesis is markedly blunted despite relatively normal protein digestion and amino acid absorption.