Spontaneous hypothermia in human sepsis is a transient, self-limiting, and nonterminal response

Abstract

Hypothermia in sepsis is generally perceived as something dysregulated and progressive although there has been no assessment on the natural course of this phenomenon in humans. This was the first study on the dynamics of hypothermia in septic patients not subjected to active rewarming, and the results were surprising. A sample of 50 subjects presenting with spontaneous hypothermia during sepsis was drawn from the 2005-2012 database of an academic hospital. Hypothermia was defined as body temperature below 36.0°C for longer than 2 h, with at least one reading of 35.5°C or less. The patients presented with 138 episodes of hypothermia, 21 at the time of the sepsis diagnosis and 117 with a later onset. However, hypothermia was uncommon in the final 12 h of life of the patients that succumbed. The majority (97.1%) of the hypothermic episodes were transient and self-limited; the median recovery time was 6 h; body temperature rarely fell below 34.0°C. Bidirectional oscillations in body temperature were evident in the course of hypothermia. Nearly half of the hypothermic episodes had onset in the absence of shock or respiratory distress, and the incidence of hypothermia was not increased during either of these conditions. Usage of antipyretic drugs, sedatives, neuroleptics, or other medications did not predict the onset of hypothermia. In conclusion, hypothermia appears to be a predominantly transient, self-limiting, and nonterminal phenomenon that is inherent to human sepsis. These characteristics resemble those of the regulated hypothermia shown to replace fever in animal models of severe systemic inflammation.

Fever Is Associated with Reduced, Hypothermia with Increased Mortality in Septic Patients: A Meta-Analysis of Clinical Trials

“…Spontaneous hypothermia represents a distinct, adaptive mechanism to systemic inflammation in experimental animals [69] and in septic patients [17]. It characteristically develops in severe cases of already progressed diseases, when—instead of actively coping with the microorganism—the organism attempts to increase survival by saving its energy resources [6, 8].…”

“…It characteristically develops in severe cases of already progressed diseases, when—instead of actively coping with the microorganism—the organism attempts to increase survival by saving its energy resources [6, 8]. A recent study by Fonseca et al [17] revealed that spontaneous hypothermia is a transient, self-limiting, and nonterminal event in human sepsis, which underlies its biological value as an adaptive mechanism in the critically ill patients.…”

“…The former characteristically occurs at the onset of an infection, representing an active fight against the pathogen, while the latter is usually associated with progressed stage or severity of the disease and it aims to secure the vital systems of the host [6, 8]. The two adaptive strategies can develop sequentially (e.g., early phase fever followed by late phase hypothermia) as the severity of the disease progresses [8], but hypothermia can be also one of the earliest developing events in animal models of endotoxin shock [16], moreover, septic patients admitted to ICU develop hypothermia more frequently in the early than in the late stages of their stay [17]. Despite the different pathological background of fever and hypothermia in systemic inflammation, both the increase and the decrease of T b are evaluated commonly as equally severe signs in the clinical praxis [15].…”

Respiratory gas exchange as a new aid to monitor acidosis in endotoxemic rats: relationship to metabolic fuel substrates and thermometabolic responses

“…), as appears to be the case for the hypothermia that develops in humans with severe sepsis (Fonseca et al. ). This thermometabolic response is usually absent in experiments performed under anesthesia, owing to the disruption of thermoregulation by anesthetics and to the use of external heating to clamp T c at ~37°C.…”

Should we assume that hypothermia is a dysfunction in sepsis?

“…Recently, though, Fonseca et al [5] published the first effort to reconcile experimental and clinical evidence on septic hypothermia. That study revealed that, similarly to animal models of endotoxemia, hypothermia in human sepsis is usually self-limiting and transient.…”