Unable to recruit to protocol

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.

Inclusion Criteria:

- all children on the paediatric intensive care unit at Great Ormond Street Hospital who

1. are likely to or have developed a fever (suspected infection, following trauma, post major surgery)
2. are over 10kg (approx 1 year of age)
3. are invasively ventilated

Exclusion Criteria:

- Children who

1. have a brain injury, where active temperature control may be instituted
2. patients post cardiac surgery
3. patient with or at risk of cardiac arrhythmias
4. patients post cardiac arrest
5. patient with refractory status epilepticus
6. children with a greater than 5% leak around the endotracheal tube
7. children with a fraction of inspired oxygen >0.6

Critically ill children admitted on the intensive care unit at risk of developing fever

Adverse event data was collected till discharge from the paediatric intensive care unit. Typically this was 7 days

Only one patient had a calorimetry measurement at baseline followed by a measurement during fever and two patients had measurements during fever and defervescence thereafter. The hypothesis that energy expenditure increases by 10% from baseline during fever could not be accurately tested.

Recruitment was difficult because fever in ICU occurs early in admission when patients at their least stable enough for calorimetry. When stabilised, fever becomes less likely despite prior history.