Measuring the Metabolic Cost of Fever

Study Overview
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Brief Summary
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Fever is part of the body's immune response, often triggered by infection. Fever is commonly treated with medicines such as paracetamol, mainly because people feel unwell with fever. However fever does have a role in fighting infection: it enables the rest of the immune system to function more efficiently, and may directly stop bacteria and viruses from multiplying. In most cases however treating fever does not matter because the rest of the immune system can cope well enough to fight the infection (with or without additional treatment, like antibiotics). In critically ill patients however any advantage in the fight against infection may be crucial. In a large observational study of adult patients in the intensive care unit, patients who developed an early fever with temperature between 38.5-39.5 degrees C fared relatively better than patients who were colder. So it is possible that in critical illness fever may be beneficial. However in critical illness the body does have limited energy resources. In order to raise the body temperature energy is required. However the investigators do not know how much energy is required to generate a fever in critically ill children. This study will aim to try and measure the energy required to generate a fever in a critically ill child. The investigators will measure energy expenditure directly in children admitted to the intensive care unit by measuring the levels of oxygen and carbon dioxide they breathe in and out (a method called indirect calorimetry). This will enable the investigators to judge whether the benefits of a fever can be justified by the energy costs in the energy depleted state that is critical illness.

Official Title
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Measuring Energy Expenditure Before and After Fever in Critically Ill Children

Conditions
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Child, Critical Illness, Fever

Intervention / Treatment
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* Device: Indirect calorimetry


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: - all children on the paediatric intensive care unit at Great Ormond Street Hospital who are likely to or have developed a fever (suspected infection, following trauma, post major surgery) are over 10kg (approx 1 year of age) are invasively ventilated Exclusion Criteria: - Children who have a brain injury, where active temperature control may be instituted patients post cardiac surgery patient with or at risk of cardiac arrhythmias patients post cardiac arrest patient with refractory status epilepticus children with a greater than 5% leak around the endotracheal tube children with a fraction of inspired oxygen >0.6

Ages Eligible for Study
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Minimum Age: 0 Years
Maximum Age: 15 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Febrile critically ill children<br>Children above 10kg admitted to the paediatric intensive care unit at Great Ormond Street Hospital who are mechanically ventilated and have a high likelihood of developing a fever. Energy expenditure will be measured using indirect calorimetry at baseline, and continuously during fever, until fever subsides. | Device: Indirect calorimetry<br>* Indirect calorimetry measurement at baseline (stable state), at onset of fever and continued till fever dehiscence<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage Change in Energy Expenditure Per Degree Celsius During Fever and Defervescence | Children at risk of fever will have energy expenditure measured by indirect calorimetry at baseline, when the develop a fever, and continuously until fever dehisces. Change in energy expenditure during fever to be calculated as difference in energy expenditure at the maximum temperature minus the energy expenditure at baseline, divided by the difference in temperature. Change in energy expenditure during defervescence to be calculated as difference in energy expenditure at the maximum temperature and the lowest temperature following the fall in temperature, divided by the difference in temperature. Both will also be expressed as a % of the starting energy expenditure (i.e. from baseline for change during fever, from maximum temperature during defervescence) | 6 hours |