Impact of prehospital airway management on combat mortality.

INTRODUCTION: Analysis of modern military conflicts suggests that airway compromise remains the second leading cause of preventable death of combat fatalities. This study compares outcomes of combat casualties that received prehospital airway interventions, specifically bag valve mask (BVM) ventilation, cricothyrotomy, and supraglottic airway (SGA) placement. The goal is to compare the effectiveness of airway management strategies used in the military pre-hospital setting. METHODS: This retrospective chart review of 1267 US Army medical evacuation patient care records, compared outcomes of casualties that received prehospital advanced airway interventions. The patients consisted of US military injured in Operation Enduring Freedom January 2011-March 2014. Compared outcomes consisted of vent-, ICU-, and hospital-free days. RESULTS: Those with SGA placement experienced fewer vent-free days, ICU-free days, and hospital-free days compared to BVM and cricothyrotomy patients. The groups did not significantly differ in rates of 30-day survival. The odds for survival were not significantly higher for BVM versus SGA patients (OR 1.5, 95% CI 0.2-9.8), cricothyrotomy versus SGA patients (OR 3.9, 95% CI 0.6-24.9), or cricothyrotomy versus BVM patients (OR 2.7, 95% CI 0.5-13.8) in a logistic regression model adjusting for GCS. CONCLUSION: This study supports prehospital BVM ventilation as a possible alternative to cricothyrotomy as there was no difference in measured outcomes between the groups. It further cautions against SGA use in the prehospital combat setting due to higher morbidity demonstrated by fewer ventilator, hospital, and ICU free days than those receiving cricothyrotomy or BVM ventilation. There was no difference in 30-day survival between the groups.

Oxygen-induced alterations in the expression of chromatin modifying enzymes and the transcriptional regulation of imprinted genes.

Embryo culture and assisted reproductive technologies have been associated with a disproportionately high number of epigenetic abnormalities in the resulting offspring. However, the mechanisms by which these techniques influence the epigenome remain poorly defined. In this study, we evaluated the capacity of oxygen concentration to influence the transcriptional control of a selection of key enzymes regulating chromatin structure. In mouse embryonic stem cells, oxygen concentrations modulated the transcriptional regulation of the TET family of enzymes, as well as the de novo methyltransferase Dnmt3a. These transcriptional changes were associated with alterations in the control of multiple imprinted genes, including H19, Igf2, Igf2r, and Peg3. Similarly, exposure of in vitro produced bovine embryos to atmospheric oxygen concentrations was associated with disruptions in the transcriptional regulation of TET1, TET3, and DNMT3a, along with the DNA methyltransferase co-factor HELLS. In addition, exposure to high oxygen was associated with alterations in the abundance of transcripts encoding members of the Polycomb repressor complex (EED and EZH2), the histone methyltransferase SETDB1 and multiple histone demethylases (KDM1A, KDM4B, and KDM4C). These disruptions were accompanied by a reduction in embryo viability and suppression of the pluripotency genes NANOG and SOX2. These experiments demonstrate that oxygen has the capacity to modulate the transcriptional control of chromatin modifying genes involved in the establishment and maintenance of both pluripotency and genomic imprinting.