Publications by authors named "David A Harrison"

Background: In Africa, severe pneumonia remains the major cause of paediatric hospitalisation, resulting in high requirements for oxygen therapy. Adequate supplies of oxygen are key challenges for many low-resource hospitals. The World Health Organization manual for oxygen therapy advises 2-3 days of oxygen therapy for pneumonia and recommends against early weaning, even in the absence of hypoxaemia.

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Importance: Supplemental oxygen is frequently given to patients in intensive care units (ICUs); however, there is insufficient evidence to guide its therapeutic use and to minimize the potential harm caused by administering too little or too much.

Objective: To determine whether reducing exposure to supplemental oxygen through a strategy of conservative oxygen therapy by using a peripheral oxygen saturation (Spo2) target of 90% (range, 88%-92%) reduces mortality at 90 days in mechanically ventilated adult patients receiving supplemental oxygen in the ICU.

Design, Setting, And Participants: Multicenter, pragmatic, randomized clinical trial conducted in 97 ICUs in the UK including 16 500 mechanically ventilated patients receiving supplemental oxygen.

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Purpose: International clinical practice guidelines addressing corticosteroid treatment for patients hospitalised with non-viral community-acquired pneumonia (CAP) are inconsistent.

Methods: We conducted a systematic review of randomized controlled trials (RCTs) evaluating the use of corticosteroids in hospitalised adult patients with suspected or probable CAP. We performed random effects pairwise, Bayesian, and dose-response meta-analyses using the restricted maximum likelihood (REML) heterogeneity estimator.

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Objectives: A conservative oxygenation strategy is recommended in adult and pediatric guidelines for the management of acute respiratory distress syndrome to reduce iatrogenic lung damage. In the recently reported Oxy-PICU trial, targeting peripheral oxygen saturations (Sp o2 ) between 88% and 92% was associated with a shorter duration of organ support and greater survival, compared with Sp o2 greater than 94%, in mechanically ventilated children following unplanned admission to PICU. We investigated whether this benefit was greater in those who had severely impaired oxygenation at randomization.

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Background: Peripheral oxygen saturation (SpO) above 94% is typical in children in paediatric intensive critical care units (PICUs) who are receiving invasive ventilation and supplemental oxygen. In a previous report from the Oxy-PICU trial, we showed that lower (conservative) oxygenation targets (SpO 88-92%) are beneficial, showing small but statistically significant differences in duration of organ support and large but non-significant cost reductions at 30 days. In this pre-specified analysis of the Oxy-PICU trial, we compare longer-term outcomes and cost-effectiveness of conservative versus liberal (SpO >94%) oxygenation targets in children with emergency PICU admission.

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Background: High flow nasal cannula therapy (HFNC) and continuous positive airway pressure (CPAP) are two widely used modes of non-invasive respiratory support in paediatric critical care units. The FIRST-ABC randomised controlled trials (RCTs) evaluated the clinical and cost-effectiveness of HFNC compared with CPAP in two distinct critical care populations: acutely ill children ('step-up' RCT) and extubated children ('step-down' RCT). Clinical effectiveness findings (time to liberation from all forms of respiratory support) showed that HFNC was non-inferior to CPAP in the step-up RCT, but failed to meet non-inferiority criteria in the step-down RCT.

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Article Synopsis
  • The study aimed to determine if setting a lower mean arterial blood pressure (MAP) target could reduce 90-day all-cause mortality in critically ill patients with vasodilatory shock compared to a higher MAP target.
  • Researchers performed a meta-analysis of randomized controlled trials involving 3,352 patients across several countries, using statistical models to analyze the data.
  • The results suggested that a lower MAP target might be associated with a slight reduction in mortality risk, but the evidence is uncertain, indicating that it does not rule out the possibility of potential harm from lower targets.
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Article Synopsis
  • Despite previous trials, it's still unclear how to effectively resuscitate patients with septic shock, prompting a deeper look into individual differences in treatment responses.
  • The study utilized machine learning to predict individual patient risk differences and evaluate how their characteristics affected treatment effectiveness across two large cohorts.
  • Results indicated significant variability in treatment responses; patients predicted to have the highest risks improved with early goal-directed therapy (EGDT), while those at lower risk potentially faced harm from the same treatment.
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Background: Adiposity shows opposing associations with mortality within COVID-19 versus non-COVID-19 respiratory conditions. We assessed the likely causality of adiposity for mortality among intensive care patients with COVID-19 versus non-COVID-19 by examining the consistency of associations across temporal and geographical contexts where biases vary.

Methods: We used data from 297 intensive care units (ICUs) in England, Wales, and Northern Ireland (Intensive Care National Audit and Research Centre Case Mix Programme).

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Objectives: A conservative oxygenation strategy, targeting peripheral oxygen saturations (Sp o2 ) between 88% and 92% in mechanically ventilated children in PICU, was associated with a shorter duration of organ support and greater survival compared with Sp o2 greater than 94% in our recent Oxy-PICU trial. Sp o2 monitors may overestimate arterial oxygen saturation (Sa o2 ) in patients with higher levels of skin pigmentation compared with those with less skin pigmentation. We investigated if ethnicity was associated with changes in distributions of Sp o2 and F io2 and outcome.

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Background: Severe pneumonia in African children results in poor long-term outcomes (deaths/readmissions) with undernutrition as a key risk factor. We hypothesised additional energy/protein-rich Ready-to-Use Therapeutic Foods (RUTF) would meet additional nutritional requirements and improve outcomes.

Methods: COAST-Nutrition was an open-label Phase 2 randomised controlled trial in children (aged 6 months-12 years) hospitalised with severe pneumonia (and hypoxaemia, SpO <92%) in Mbale, Soroti, Jinja, Masaka Regional Referral Hospitals, Uganda and Kilifi County Hospital, Kenya (ISRCTN10829073 (registered 6th June 2018) PACTR202106635355751 (registered 2nd June 2021)).

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Background: In the United Kingdom, around 184,000 adults are admitted to an intensive care unit (ICU) each year with over 30% receiving mechanical ventilation. Oxygen is the commonest therapeutic intervention provided to these patients but it is unclear how much oxygen should be administered for the best clinical outcomes.

Methods: The UK-ROX trial will evaluate the clinical and cost-effectiveness of conservative oxygen therapy (the minimum oxygen concentration required to maintain an oxygen saturation of 90% ± 2%) versus usual oxygen therapy in critically ill adults receiving supplemental oxygen when invasively mechanically ventilated in ICUs in England, Wales and Northern Ireland.

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Objectives: Management of hypotension is a fundamental part of pediatric critical care, with cardiovascular support in the form of fluids or vasoactive drugs offered to every hypotensive child. However, optimal blood pressure (BP) targets are unknown. The PRotocolised Evaluation of PermiSSive BP Targets Versus Usual CaRE (PRESSURE) trial aims to evaluate the clinical and cost-effectiveness of a permissive mean arterial pressure (MAP) target of greater than a fifth centile for age compared with usual care.

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Background: Healthcare-associated infections are a major cause of morbidity and mortality in critically ill children. In adults, data suggest the use of selective decontamination of the digestive tract may reduce the incidence of healthcare-associated infections. Selective decontamination of the digestive tract has not been evaluated in the paediatric intensive care unit population.

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Background: Healthcare system data (HSD) are increasingly used in clinical trials, augmenting or replacing traditional methods of collecting outcome data. This study, PRIMORANT, set out to identify, in the UK context, issues to be considered before the decision to use HSD for outcome data in a clinical trial is finalised, a methodological question prioritised by the clinical trials community.

Methods: The PRIMORANT study had three phases.

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Sepsis is a frequent cause of ICU admission and mortality. To evaluate temporal trends in the presentation and outcomes of patients admitted to the ICU with sepsis and to assess the contribution of changing case mix to outcomes. We conducted a retrospective cohort study of patients admitted to 261 ICUs in the United Kingdom during 1988-1990 and 1996-2019 with nonsurgical sepsis.

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Background: The optimal target for systemic oxygenation in critically ill children is unknown. Liberal oxygenation is widely practiced, but has been associated with harm in paediatric patients. We aimed to evaluate whether conservative oxygenation would reduce duration of organ support or incidence of death compared to standard care.

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Article Synopsis
  • The study aimed to evaluate the effectiveness of simvastatin in critically ill Covid-19 patients compared to a control group not receiving statins.
  • A total of 2684 patients were analyzed, showing a median of 11 organ support-free days in the simvastatin group versus 7 in the control group, with a high probability indicating simvastatin’s potential superiority.
  • However, the study was halted due to decreasing Covid-19 cases, and while simvastatin had some benefits, it also led to more reported serious adverse effects, such as elevated liver enzymes.
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Background: Oxygen is the commonest intervention provided to critically ill patients requiring mechanical ventilation. Despite this, it is unclear how much oxygen should be administered to patients in order to promote the best clinical outcomes and it has been suggested that a strategy of conservative oxygen therapy (COT) may be advantageous. We therefore sought to answer the question of whether COT versus usual or liberal oxygen therapy was beneficial to adult patients receiving mechanical ventilation on an intensive care unit (ICU) by performing a systematic review and meta-analysis.

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Background: Persistent critical illness is a recognisable clinical syndrome defined conceptually as when the patient's reason for being in the intensive care unit (ICU) is more related to their ongoing critical illness than their original reason for admission. Our objectives were: (1) to assess the day in ICU on which chronic factors (e.g.

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Article Synopsis
  • Overactivation of the renin-angiotensin system (RAS) could lead to worse outcomes for COVID-19 patients, prompting a study to see if ACE inhibitors or ARBs could help.
  • In a clinical trial with 721 patients, participants were randomly assigned to receive either an ACE inhibitor, an ARB, or no RAS inhibitor to evaluate their effects on patient recovery.
  • Results showed no significant improvement in organ support-free days among the treatment groups compared to the control, leading to the discontinuation of enrollment due to safety concerns.
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Aims: The incidence of in hospital cardiac arrest (IHCA) varies throughout the day. This study aimed to report the variation in incidence of IHCA, presenting rhythm and outcome based on the hour in which IHCA occurred.

Methods: We conducted a retrospective analysis of the National Cardiac Arrest Audit (NCAA) including patients who suffered an IHCA from 1st April 2011 to 31st December 2019.

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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.

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