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

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.

Functional outcomes at PICU discharge in hemato-oncology children at a tertiary oncology center in Hong Kong

BACKGROUND

Advancements in cancer treatment have resulted in longer survival but often at the expense of new therapy-associated morbidities. The aim of this study is to evaluate functional outcomes of hemato-oncology patients at PICU discharge, and to identify associated risk factors.

METHODS

A single-center retrospective observational study. All children (< 19 years) with a hemato-oncology diagnosis admitted to the Hong Kong Children's Hospital PICU over a 2-year period were included. Functional status upon admission and discharge were compared. Univariable and multi-variable analyses were employed to identify risk factors associated with new morbidities.

RESULTS

Out of 288 PICU admissions, there were 277 live discharges (mortality 4%), of which 52 (18.8%) developed new morbidities. Emergency admission, severity of illness at admission, organ dysfunction and support were associated with new morbidities (OR 1.08-11.96; p < 0.05). Adjusting for confounding factors, higher Pediatric Logistic Organ Dysfunction 2 score at admission was significantly associated with development of new morbidities (OR 1.34; 95% CI 1.18-1.54; p < 0.001).

CONCLUSION

Critically ill children with hemato-oncological diseases had a higher rate of developing new morbidities (18.8%) compared with the general PICU population (4-8%). This was associated with severity of illness at admission. Further work is warranted to understand the lasting effects of these new morbidities and mitigating interventions.

[Paediatric Life Support]

The European Resuscitation Council (ERC) Paediatric Life Support (PLS) guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations of the International Liaison Committee on Resuscitation (ILCOR). This section provides guidelines on the management of critically ill or injured infants, children and adolescents before, during and after respiratory/cardiac arrest.

European Resuscitation Council Guidelines 2021: Paediatric Life Support

These European Resuscitation Council Paediatric Life Support (PLS) guidelines, are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the management of critically ill infants and children, before, during and after cardiac arrest.

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.