Body temperature in sepsis: a hot topic

Abstract

The core temperature of most animals varies with ambient temperature, a phenomenon called poikilothermia. However, humans, like other mammals and birds, are homeothermic, meaning that they are able to keep their central temperature at 37°C with only small fluctuations of about 0·5°C. 1 Cabanac M Temperature regulation. Annu Rev Physiol. 1965; 37: 415-439 Crossref Scopus (135) Google Scholar The hypothalamus regulates body temperature by controlling three main physiological responses: skin vasomotor tone, skeletal muscle tone and shivering, and sweating. Central temperature can be shifted outside the normal range by two mechanisms. First, hypothermia and hyperthermia might occur in response to extreme ambient temperatures, illnesses or interventions, such as general anaesthesia, or vasoactive drugs. Second, fever is characterised by a preserved thermoregulation and resetting of central temperature to 38–39°C. Among the factors that can alter the hypothalamus, pathogens, toxic substances, and cancers are the most common. In these conditions, fever is triggered by molecular patterns associated with peripheral damage. Next, the brain is notified via autonomic nervous system fibres and blood-borne soluble mediators, then the activation of enzymes in the hypothalamus contributes to the reset of central temperature to 38–39°C. 2 Dantzer R Wollman EF Molecular mechanisms of fever: the missing links. Eur Cytokine Netw. 1998; 9: 27-31 PubMed Google Scholar Fever can be seen as part of an adaptive response to infections or inflammation aiming to reorganise the priorities of the critically ill host. Thus, during sepsis, body temperature mainly results from the balance between pathogen-induced fever and drug-related downregulation of physiological responses against hypothermia. Induced hypothermia in patients with septic shock and respiratory failure (CASS): a randomised, controlled, open-label trialAmong patients with septic shock and ventilator-dependent respiratory failure, induced hypothermia does not reduce mortality. Induced hypothermia should not be used in patients with septic shock. Full-Text PDF