• Adolfo Shepherd posted an update 3 months ago

    These observations were made in animal experiments, but the hypothermia-induced suppression of the hyperinflammatory responses and decrease in WBC count have been confirmed in clinical reports in humans with traumatic brain injury [10,11,17]. Thus the very mechanisms that provide tissue protection could simultaneously impair the patients’ ability to fight infections. In ZL006 web addition, lowering body temperature can lead to a decrease in insulin secretion and to induction of insulin resistance [2,3]. This can lead to hyperglycaemia, which can in turn impair leucocyte function and further increase infection risks. Finally, hypothermia can cause vasoconstriction in the skin, which could increase the risk for bedsores and surgical wound infections. In summary, based on the in vitro evidence we would expect hypothermia to inhibit the mostly harmful neuroinflammatory response and ameliorate the hyperinflammatory state that occurs after acute injury, but at the price of increasing infection risk. Clinical evidence: Clinical studies reporting the infection risks associated with therapeutic cooling in different categories of patients with acute brain injury have produced divergent results; studies in patients who develop accidental hypothermia have mostly reported higher infection risks. The link between accidental hypothermia in the perioperative setting and a higher incidence of surgical wound infections was first demonstrated by Kurz and coworkers in 1996 [18], and has since been confirmed in numerous studies in various categories of surgical patients [19-26]. The most recent example is a study by Seamon and coworkers, who found that intraoperative hypothermia (below 35 ) was independently associated with surgical site infection rates after trauma laparotomy [26]. Local factors such as hypothermia-induced vasoconstriction in the skin may add to the underlying immunosuppressive effect to further increase the rate of wound infections. Recently, Laupland and colleagues reported that severe hypothermia (<32 , but not 32 to 35.9 ) was associated with significant increases in risk for infections acquired in ICU [27]. The link between hypothermia and infections is far less clear when mild hypothermia is induced under controlled circumstances. Numerous studies in patients with post-hypoxic brain injury following cardiac arrest have not reported significant increases in rates of infections, although some have reported trends in that direction [28]. Seven multicentered trials in newborn babies treated with neonatal asphyxia for 48 to 72 hours also did not report consistent increases in infection risks [28]. In contrast, clinical studies in patients with ischemic stroke and TBI have tended to find higher risks of infection, especially pneumonia, in patients treated with hypothermia. For example, Hemmen and coworkers reported a rate of pneumonia of 50 in patients with ischemic stroke treated with hypothermia and thrombolysis, compared to 10 in controls [29]. Although the overall outcome was better in hypothermia patients in spite of the high infection rate, this indicates that use of hypothermia in these patients may present significant difficulties. Some studies using hypothermia in patients with severe traumatic brain injury have also reported high infection rates [28]. There is evidence that this can be prevented by a combination of preventive measures, perhaps including use of antibiotic prophylaxis such as selective decontamination of the digestive trac.