Iron diapirs entrain silicates to the core and initiate thermochemical plumes.

Segregation of the iron core from rocky silicates is a massive evolutionary event in planetary accretion, yet the process of metal segregation remains obscure, due to obstacles in simulating the extreme physical properties of liquid iron and silicates at finite length scales. We present new experimental results studying gravitational instability of an emulsified liquid gallium layer, initially at rest at the interface between two glucose solutions. Metal settling coats liquid metal drops with a film of low density material. The emulsified metal pond descends as a coherent Rayleigh-Taylor instability with a trailing fluid-filled conduit. Scaling to planetary interiors and high pressure mineral experiments indicates that molten silicates and volatiles are entrained toward the iron core and initiate buoyant thermochemical plumes that later oxidize and hydrate the upper mantle. Surface volcanism from thermochemical plumes releases oxygen and volatiles linking atmospheric growth to the Earth's mantle and core processes.

Survival among injured geriatric patients during construction of a statewide trauma system.

BACKGROUND: Patient outcomes are presumed to vary during early implementation of a trauma system because of fluctuations in processes of care. This study estimates risk-adjusted survival for injured geriatric patients during implementation of the Washington State trauma system. METHODS: A presystem (1988-1992) versus early construction phase (1993-1995) retrospective cohort analysis of hospitalized geriatric injured patients in Washington State was conducted. Hospital data were cross-linked to death certificates, providing patient follow-up. A Cox proportional hazards model assessed survival to 60 days from hospital admission. RESULTS: A total of 77,136 geriatric patients were assessed. No difference in survival was observed (before vs. after) for all geriatric injured patients. However, among severely injured patients (Injury Severity Score > 15), survival during the implementation phase increased by 5.1% compared with patients admitted during the presystem years (p = 0.03). CONCLUSION: This study demonstrates improved survival for seriously injured geriatric trauma patients during construction of the Washington State trauma system.

Weaning injured patients with prolonged pulmonary failure from mechanical ventilation in a non-intensive care unit setting.

BACKGROUND: Injured patients with pulmonary failure often require prolonged length of stay in an intensive care unit (ICU), which includes weaning from ventilatory support. In the last decade, noninvasive ventilation modes have been established as safe and effective. One method for accomplishing this mode of ventilation uses a simple bilevel ventilator. Because this ventilator has been successfully used in hospital wards, we postulated that bilevel ventilators could provide sufficient support during weaning from mechanical ventilation of injured patients in a non-ICU setting. METHODS: A retrospective review of trauma patients (August 1996-January 1999) undergoing bilevel positive pressure ventilation as the final phase of weaning was conducted. Before ward transfer with bilevel ventilation, conventionally ventilated ICU patients were changed to bilevel ventilation and were required to tolerate this mode for at least 24 hours. All patients had a tracheostomy as a secure airway. Outcomes analyzed included ICU length of stay, hospital length of stay, duration of mechanical ventilation, weaning success, complications, and survival. RESULTS: Fifty-one patients (39 men, 12 women) with a mean age of 53 received more than 24 hours of bilevel positive pressure ventilation. Mean Injury Severity Score was 29, with blunt mechanisms of injury occurring in 90%. Chest or spinal cord injuries that affected pulmonary mechanics were present in 75% of patients. Ventilator-associated pneumonia was treated in 43% of patients. Mean ICU length of stay and hospital length of stay were 21 and 34 days, respectively. Weaning was successful in 89% of patients, whereas 11% were discharged to skilled nursing facilities still receiving bilevel positive pressure ventilation. Two patients died, neither from a pulmonary nor airway complication. Of the remaining 49 patients, 12 were weaned in the ICU and 37 were transferred to the ward with bilevel ventilatory support. The average length of ward ventilation was 6.5 +/- 5.4 days (n = 37). CONCLUSIONS: Implementation of a program using bilevel ventilation to support the terminal phase of weaning seriously injured patients from mechanical ventilation was successful. After initiating this mode in the ICU, it was satisfactorily continued in standard surgical wards. Because this method enabled the withdrawal of ventilatory support in a non-ICU setting, its major advantage was reducing ICU length of stay.

Surveyed opinion of American trauma surgeons on the prevention of the abdominal compartment syndrome.

OBJECTIVE: To determine the current opinion of American trauma surgeons on the use of the open abdomen to prevent the abdominal compartment syndrome (ACS). METHODS: On a questionnaire survey of expert trauma surgeons regarding 12 clinical factors influencing fascial closure at trauma celiotomy, surgeons graded their willingness to close the fascia in various scenarios on a scale of 1 to 5. The impact of six signs of clinical deterioration on willingness to perform abdominal decompression in a patient with postceliotomy elevated intra-abdominal pressure (IAP) was also queried. Of 292 members of the American Association for the Surgery of Trauma active in abdominal trauma management, 248 members (85%) had experience with ACS one or more times in the previous year. RESULTS: Surgeons' responses to factors found at trauma celiotomy were divided into two distinct categories: factors decreasing willingness to close the fascia, and factors not changing or increasing willingness to close the fascia (p < 0.001). Factors disfavoring fascial closure were pulmonary or hemodynamic deterioration with closure, massive bowel edema, subjectively tight closure, planned reoperation, and packing. Factors not changing or favoring fascial closure were fecal contamination/peritonitis, massive transfusion, hypothermia, multiple abdominal injuries, acidosis, and coagulopathy. Five of the six signs of clinical deterioration increased surgeons' willingness to decompress a patient with elevated IAP (increased O2 requirement, decreased cardiac output, increased acidosis, increased airway pressures, and oliguria). Lowered gastric mucosal pH did not affect willingness. Seventy-one percent of surgeons indicated they would decompress elevated IAP in postceliotomy patient if one or two signs of clinical deterioration were present, but only 14% would decompress a patient for elevated IAP alone. CONCLUSION: A majority of expert American trauma surgeons have experience with ACS and would leave the abdomen open if ACS occurred. A majority would reopen a closed abdomen in cases of elevated IAP with signs of clinical deterioration. A minority would leave the abdomen open when there was only a risk of developing ACS.

Surveyed opinion of American trauma surgeons in management of colon injuries.

BACKGROUND: Primary repair or resection and anastomosis of colon wounds have been advocated in many recent studies, but the proportion of trauma surgeons accepting these recommendations is unknown. OBJECTIVE: To determine the current preferences of American trauma surgeons for colon injury management. METHODS: Four hundred forty-nine members of the American Association for the Surgery of Trauma were surveyed regarding their preferred management of eight types of colon wounds among three options: diverting colostomy (DC), primary repair (PR), or resection and anastomosis (RA). The influence of selected patient factors and surgeons' characteristics on the choice of management was also surveyed. RESULTS: Seventy-three percent of surgeons completed the survey. Ninety-eight percent chose PR for at least one type of injury. Thirty percent never selected DC. High-velocity gunshot wound was the only injury for which the majority (54%) would perform DC. More than 55% of the surgeons favored RA when the isolated colon injury was a contusion with possible devascularization, laceration greater than 50% of the diameter, or transection. Surgeons who managed five or fewer colon wounds per year chose DC more frequently (p < 0.001) and PR less frequently (p < 0.001) than surgeons who managed six or more colon wounds per year. CONCLUSION: The prevailing opinion of trauma surgeons favors primary repair or resection of colon injuries, including anastomosis of unprepared bowel. Surgeons who manage fewer colon wounds prefer colostomy more frequently.

Specifications for calculation of risk-adjusted odds of death using trauma registry data.

BACKGROUND: Logistic regression models, with coefficients developed from normative populations, can be applied to a trauma registry cohort to predict the risk-adjusted frequency of death. Quality of care is judged based on differences between predicted and observed mortality frequency. The goal of these analyses was to determine if decedents who died in the emergency department had independent variables associated with risk of death identical to those who died after hospital admission. METHODS: This case-control study is based upon decedents in a trauma registry matched to survivors. Backward stepwise linear logistic regression models contained independent variables selected to reflect patients' status before treatment. RESULTS: Beta coefficients and independent variables selected for models of expired emergency department patients were different from those of hospital death patients. CONCLUSIONS: To achieve a more precise determination of risk-adjusted mortality for injured patients at a trauma center, two separate analyses are appropriate: death in emergency department and death after hospital admission.

Shipboard medical information systems: familiarity and receptivity.

Analyses were performed on the perceived automation needs and current medical department computerization status aboard ships of the U.S. Pacific Fleet to determine if present automation status had a bearing on receptivity to further automation. Current medical department automation status consisted of microcomputers and/or the Shipboard Nontactical ADP Program (SNAP). Measures of receptivity to department automation included perceived need for automation of reports and composite scores of perceived need for 12 automated medical capabilities. Those ships with the highest present levels of automation were the most receptive to medical department computerization. Lack of familiarity with benefits to be attained through automation was proposed as responsible for observed decrements in receptivity among medical departments.