Randomization to a Liberal Versus Conservative Oxygenation Target: Redox Responses in Critically Ill Children.

RATIONALE: Optimal systemic oxygenation targets in pediatric critical illness are unknown. A U-shaped relationship exists between blood oxygen levels and PICU mortality. Redox stress or iatrogenic injury from intensive treatments are potential mechanisms of harm from hyperoxia. OBJECTIVES: To measure biomarkers of oxidative status in children admitted to PICU and randomized to conservative (oxygen-hemoglobin saturation [Sp o2 ] 88-92%) versus liberal (Sp o2 > 94%) peripheral oxygenation targets. DESIGN: Mechanistic substudy nested within the Oxygen in PICU (Oxy-PICU) pilot randomized feasibility clinical trial ( ClinicalTrials.gov : NCT03040570). SETTING: Three U.K. mixed medical and surgical PICUs in university hospitals. PATIENTS: Seventy-five eligible patients randomized to the Oxy-PICU randomized feasibility clinical trial. INTERVENTIONS: Randomization to a conservative (Sp o2 88-92%) versus liberal (Sp o2 > 94%) peripheral oxygenation target. MEASUREMENTS AND MAIN RESULTS: Blood and urine samples were collected at two timepoints: less than 24 hours and up to 72 hours from randomization in trial participants (March 2017 to July 2017). Plasma was analyzed for markers of ischemic/oxidative response, namely thiobarbituric acid-reactive substances (TBARS; lipid peroxidation marker) and ischemia-modified albumin (protein oxidation marker). Total urinary nitrate/nitrite was measured as a marker of reactive oxygen and nitrogen species (RONS). Blood hypoxia-inducible factor (HIF)-1a messenger RNA (mRNA) expression (hypoxia response gene) was measured by reverse transcription- polymerase chain reaction. Total urinary nitrate/nitrite levels were greater in the liberal compared with conservative oxygenation group at 72 hours (median difference 32.6 µmol/mmol of creatinine [95% CI 13.7-93.6]; p < 0.002, Mann-Whitney test). HIF-1a mRNA expression was increased in the conservative group compared with liberal in less than 24-hour samples (6.0-fold [95% CI 1.3-24.0]; p = 0.032). There were no significant differences in TBARS or ischemia-modified albumin. CONCLUSIONS: On comparing liberal with conservative oxygenation targets, we show, first, significant redox response (increase in urinary markers of RONS), but no changes in markers of lipid or protein oxidation. We also show what appears to be an early hypoxic response (increase in HIF-1a gene expression) in subjects exposed to conservative rather than liberal oxygenation targets.

Effect of Stress Ulcer Prophylaxis With Proton Pump Inhibitors vs Histamine-2 Receptor Blockers on In-Hospital Mortality Among ICU Patients Receiving Invasive Mechanical Ventilation: The PEPTIC Randomized Clinical Trial.

Importance: Proton pump inhibitors (PPIs) or histamine-2 receptor blockers (H2RBs) are often prescribed for patients as stress ulcer prophylaxis drugs in the intensive care unit (ICU). The comparative effect of these drugs on mortality is unknown. Objective: To compare in-hospital mortality rates using PPIs vs H2RBs for stress ulcer prophylaxis. Design, Setting, and Participants: Cluster crossover randomized clinical trial conducted at 50 ICUs in 5 countries between August 2016 and January 2019. Patients requiring invasive mechanical ventilation within 24 hours of ICU admission were followed up for 90 days at the hospital. Interventions: Two stress ulcer prophylaxis strategies were compared (preferential use with PPIs vs preferential use with H2RBs). Each ICU used each strategy sequentially for 6 months in random order; 25 ICUs were randomized to the sequence with use of PPIs and then use of H2RBs and 25 ICUs were randomized to the sequence with use of H2RBs and then use of PPIs (13 436 patients randomized by site to PPIs and 13 392 randomized by site to H2RBs). Main Outcomes and Measures: The primary outcome was all-cause mortality within 90 days during index hospitalization. Secondary outcomes were clinically important upper gastrointestinal bleeding, Clostridioides difficile infection, and ICU and hospital lengths of stay. Results: Among 26 982 patients who were randomized, 154 opted out, and 26 828 were analyzed (mean [SD] age, 58 [17.0] years; 9691 [36.1%] were women). There were 26 771 patients (99.2%) included in the mortality analysis; 2459 of 13 415 patients (18.3%) in the PPI group died at the hospital by day 90 and 2333 of 13 356 patients (17.5%) in the H2RB group died at the hospital by day 90 (risk ratio, 1.05 [95% CI, 1.00 to 1.10]; absolute risk difference, 0.93 percentage points [95% CI, -0.01 to 1.88] percentage points; P = .054). An estimated 4.1% of patients randomized by ICU site to PPIs actually received H2RBs and an estimated 20.1% of patients randomized by ICU site to H2RBs actually received PPIs. Clinically important upper gastrointestinal bleeding occurred in 1.3% of the PPI group and 1.8% of the H2RB group (risk ratio, 0.73 [95% CI, 0.57 to 0.92]; absolute risk difference, -0.51 percentage points [95% CI, -0.90 to -0.12 percentage points]; P = .009). Rates of Clostridioides difficile infection and ICU and hospital lengths of stay were not significantly different by treatment group. One adverse event (an allergic reaction) was reported in 1 patient in the PPI group. Conclusions and Relevance: Among ICU patients requiring mechanical ventilation, a strategy of stress ulcer prophylaxis with use of proton pump inhibitors vs histamine-2 receptor blockers resulted in hospital mortality rates of 18.3% vs 17.5%, respectively, a difference that did not reach the significance threshold. However, study interpretation may be limited by crossover in the use of the assigned medication. Trial Registration: anzctr.org.au Identifier: ACTRN12616000481471.

Conservative versus liberal oxygenation targets in critically ill children: the randomised multiple-centre pilot Oxy-PICU trial.

BACKGROUND: Oxygen saturation monitoring for children receiving respiratory support is standard worldwide. No randomised clinical trials have compared peripheral oxygen saturation (SpO2) targets for critically ill children. The harm of interventions to raise SpO2 to > 94% may exceed their benefits. METHODS: We undertook an open, parallel-group randomised trial of children > 38 weeks completed gestation and < 16 years of age receiving invasive or non-invasive respiratory support and supplemental oxygen who were admitted urgently to one of three paediatric intensive care units. A 'research without prior consent' approach was employed. Children were randomly assigned to a liberal oxygenation group (SpO2 targets > 94%) or a conservative oxygenation group (SpO2 = 88-92% inclusive). Outcomes were measures of feasibility: recruitment rate, protocol adherence and acceptability, between-group separation of SpO2 and safety. The Oxy-PICU trial was registered before recruitment: ClinicalTrials.gov identifier NCT03040570. RESULTS: A total of 159 children met the inclusion criteria, of whom 119 (75%) were randomised between April and July 2017, representing a rate of 10 patients per month per site. The mean time to randomisation from first contact with an intensive care team was 1.9 (SD 2.2) h. Consent to continue in the study was obtained in 107 cases (90%); the children's parents/legal representatives were supportive of the consent process. The median (interquartile range, IQR) of time-weighted individual mean SpO2 was 94.9% (92.6-97.1) in the conservative oxygenation group and 97.5% (96.2-98.4) in the liberal group [difference 2.7%, 95% confidence interval (95% CI) 1.3-4.0%, p < 0.001]. Median (IQR) time-weighted individual mean FiO2 was 0.28 (0.24-0.37) in the conservative group and 0.37 (0.30-0.42) in the liberal group (difference 0.08, 95% CI 0.03-0.13, p < 0.001). There were no significant between-group differences in length of stay, duration of organ support or mortality. Two prespecified serious adverse events (cardiac arrests) occurred, both in the liberal oxygenation group. CONCLUSION: A definitive clinical trial of peripheral oxygen saturation targets is feasible in critically ill children.

Protocol for a randomised pilot multiple centre trial of conservative versus liberal oxygenation targets in critically ill children (Oxy-PICU).

INTRODUCTION: Optimal targets for systemic oxygenation in paediatric critical illness are unknown. Observational data indicate that high levels of arterial oxygenation are associated with poor outcomes in resuscitation of the newborn and in adult critical illness. Within paediatric intensive care units (PICUs), staff prevent severe hypoxia wherever possible, but beyond this there is no consensus. Practice varies widely with age, diagnosis, treating doctor and local or national guidelines followed, though peripheral blood oxygen saturations (SpO2) of >95% are often targeted. The overall aim of this pilot study is to determine the feasibility of performing a randomised trial in critically ill children comparing current practice of liberal SpO2 targets with a more conservative target. METHODS AND ANALYSIS: Oxy-PICU is a pragmatic, open, pilot randomised controlled trial in infants and children requiring mechanical ventilation and receiving supplemental oxygen for abnormal gas exchange accepted for emergency admission to one of three participating UK PICUs. The study groups will be either a conservative SpO2 target of 88%-92% (inclusive) or a liberal SpO2 target of >94%. Infants and children who fulfil all inclusion criteria and none of the exclusion criteria will be randomised 1:1 by a secure web-based system to one of the two groups. Baseline demographics and clinical status will be recorded as well as daily measures of oxygenation and organ support. Discharge outcomes will also be recorded. In addition to observational data, blood and urine samples will be taken to identify biochemical markers of oxidative stress. Outcomes are targeted at assessing study feasibility with a primary outcome of adequate study recruitment (target: 120 participants). ETHICS AND DISSEMINATION: The trial received Health Research Authority approval on 1 June 2017 (16/SC/0617). Study findings will be disseminated in national and international conferences and peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT03040570.