News briefs

Brain cooling after traumatic head injury does not improve outcomes

An international team led by researchers from Monash University have found that cooling patients’ brains after traumatic head injury does not improve outcomes, compared with patients who did not undergo brain cooling. The benefits of brain cooling in the intensive care unit after a traumatic brain injury have long been contentious. The rationale is that cooling, or hypothermia, reduces brain inflammation and consequently brain damage. Many laboratory studies have supported this hypothesis, and most clinical studies and the traumatic brain injury guidelines have found benefits for patients. However, many doctors remain skeptical about cooling because most clinical studies have not been of high quality, the better studies had limitations, and hypothermia requires expensive equipment and has known complications. The Prophylactic Hypothermia Trial to Lessen Traumatic Brain Injury (POLAR) was a multicentre randomised trial that included 511 patients with traumatic brain injury in six countries — France, Switzerland, Qatar, Saudi Arabia, Australia and New Zealand — and found that the proportion of patients with favourable neurological outcomes 6 months after brain trauma was the same whether patients had undergone cooling or not (cooling, 48.8%; normal temperature, 49.1%). Favourable neurological outcome was defined as a Glasgow Outcome Scale – Extended (GOS-E) score of 5–8 (a GOS-E score of 1 indicates death, 2 indicates vegetative state, 3–4 indicates severe disability, 5–6 indicates moderate disability, and 7–8 indicates good recovery). Mortality at 6 months was 21.4% for patients with hypothermia, and 18.4% for those with a normal temperature target. Findings were similar after adjusting the analysis for the severity of the injury and for the analysis of specific patient subgroups. The POLAR trial was presented at the annual meeting of the European Society of Intensive Care Medicine and published simultaneously in JAMA.

https://jamanetwork.com/journals/jama/fullarticle/2710778

Infant gut flora gives insights into disease

Investigators have examined more than 20 000 stool samples to look at how the microbiome changes over time, and to investigate associations between the microbiome, infant development, and the potential impact of type 1 diabetes. The Environmental Determinants of Diabetes in the Young (TEDDY) study has generated one of the largest datasets on the infant microbiome to date, with samples from six clinical centres in the United States, Sweden, Germany and Finland. In the first of two articles published in Nature, the researchers sequenced genes in 12 500 stool samples collected monthly from 903 children aged 3–46 months. Microbiome composition and diversity changed over time in three distinct phases: the developmental phase (3–14 months), transitional phase (15–30 months), and stable phase (31 months onwards). During the developmental stage, breastfeeding was associated with higher levels of Bifidobacterium, whereas microbiome diversity increased after weaning as the infants consumed a greater variety of foods. Vaginal birth was associated with a temporary increase in Bacteroides numbers; higher Bacteroides levels were generally associated with increased gut diversity and maturation, regardless of birth mode. Siblings, exposure to pets, and geographic location were also factors in differences between microbiome profiles. In the second article, researchers analysed nearly 11 000 stool samples from 783 infants in the TEDDY study to characterise the early gut microbiome of children who developed type 1 diabetes. They found that the microbiomes of infants without type 1 diabetes included more genes related to fermentation and short-chain fatty acid synthesis, a finding that, in combination with previous evidence, suggests they have protective effects. The authors noted that the infants sampled (mostly non-Hispanic white infants at high risk of type 1 diabetes) may not be representative of other populations.

https://www.nature.com/articles/s41586-018-0617-x

https://www.nature.com/articles/s41586-018-0620-2