Do iatrogenic factors bias the placement of external ventricular catheters? A single institute experience and review of the literature

Placement of external ventricular drainage (EVD) catheters is the gold standard for managing acute hydrocephalus, but the range of complications varies in different studies. The objective of this present single institute study is to analyze iatrogenic factors, which may influence the EVD device placement and the patient's outcome. A total of 137 EVD placements in 120 patients at the University Hospital Zurich were analyzed retrospectively. Discriminative findings between the pre- and postoperative imaging were obtained and evaluated in detail with regards to the postoperative course, ventriculostomy-related infection, and acute neurological deterioration directly related to the EVD placement. These findings were correlated to iatrogenic factors including education level of the neurosurgeon and surgical setting. Overall EVD-related complication rate was 16.1%, including infection rate of 10.2%, catheter malplacement rate of 2.2%, and hemorrhage rate of 3.6%. Although not statistically significant, catheter-associated hemorrhages and malplacements were found mostly in primary EVD surgery, with a higher complication rate associated with junior residents as the performing surgeon. In contrast, ventriculostomy-related infection was most likely present in patients with more than one EVD placement and in patients treated by more experienced physicians. Complications related to EVD are common. The rate and character of the complication depends on the education level of the surgeon

Vulnerability analysis of the rare and endangered woodland fern Polystichum braunii

Background: Various rare and endangered temperate ferns are being threatened by their recent population decline, but there is limited understanding of the causes behind it. Aims: This study attempted to identify the possible drivers of regional population decline and extinction in the globally distributed woodland fern Polystichum braunii. Methods: A comparison was undertaken of the climatic, edaphic and phytosociological characteristics of sites with increasing, decreasing or recently extinct populations in Germany. Results: A significantly higher frequency of episodes of low relative air humidity (<60%) was found at sites with decreasing or extinct populations compared to habitats with population increases. Sites with decreasing or extinct populations were also characterised as having less summer precipitation (<500 mm year−1) and a shorter duration of snow cover (<110 days year−1) than sites with increasing populations. The latter had significantly higher moss cover (56% of the forest floor), but less cover by a tree litter layer (23%) compared to decreasing (36% and 38%) or recently extinct populations (22% and 52%). All increasing populations were located in intact Tilia – Acer ravine forests, while those suffering population decline were mostly located in Fagus-dominated forests. Conclusions: It was concluded that the probable causes of the recent decline in German P. braunii populations are reduced air humidity levels, decreasing snow duration or a shift from moss-covered to tree litter-covered forest floors due to climate warming or altered forest management