Regional characterization of Western China

Geological, geophysical, and seismic data are being assembled and organized into a knowledge base for Western China as part of the CTBT Research and Development regional characterization effort. We have begun our analysis using data from the station WMQ of the Chinese Digital Seismic Network (CDSN). Regional seismograms are being analyzed to construct travel time curves, velocity models, attenuation characteristics, and to quantify regional propagation effects such as phase blockages. Using locations from the USGS Preliminary Determination of Epicenters (PDE) we have identified Pn, Pg, Sn, and Lg phases, constructed travel time curves, and estimated apparent velocities using linear regression. Surface wave group velocities will be measured and inverted for regional structure. Preliminary noise spectra for WMQ have been obtained from the IRIS DMC. Chinese seismicity catalogs from the USGS and SSB are being used to identify and obtain seismic data (including mine seismicity) and information for lower magnitude events. We have identified the locations of nearly 500 mines in China for inclusion in the knowledge base. Future work will involve expanding the data collection and analysis efforts to a larger region using data from additional CDSN, IRIS and portable stations

Severe hepatic trauma: a multi-center experience with 1,335 liver injuries.

The experience of six regional trauma centers with severe hepatic trauma was reviewed to identify trends in management, mortality, and postoperative complications. During the 5-year period ending June 1987, 210 complex liver injuries were identified at laparotomy. There were 92 Class III, 59 Class IV, and 59 Class V injuries. Mechanism of injury was blunt in 101 (48%) patients and penetrating in 109 (52%). Shock was observed in 38%, 46%, and 85% of Class III, IV, and V patients, respectively. Emergency department thoracotomy was performed in 31 patients. There was only one (3%) survivor. Resuscitative operating room thoracotomy was performed in 34 patients with three (9%) survivors. Class III injuries were most frequently treated with hepatotomy and individual vessel ligation (41%) and deep liver suturing (25%). Class IV injuries were most often managed by resectional debridement (36%). Class V injuries required caval shunt placement in 38 (64%) patients. There were only four (10%) survivors after caval shunt placement. There were 20 (59%) survivors of 34 patients treated with packing placed as an adjunct after hepatic injury repair. There was no significant increase in the incidence of abscess formation after perihepatic packing. Routine peritoneal drainage was used in 94% of patients. Overall mortality rates for Class III, IV, and V injuries were 25%, 46%, and 80%, respectively (p less than 0.01). Death rates due to the liver injury in Class III, IV, and V patients were 7%, 30%, and 66%, respectively (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS

Nonoperative management of blunt splenic trauma: a multicenter experience.

The experience of six referral trauma centers with 832 blunt splenic injuries was reviewed to determine the indications, methods, and outcome of nonoperative management. During this 5-year period, 112 splenic injuries were intentionally managed by observation. There were 40 (36%) patients less than 16 years old and 72 adults. The diagnosis was established by computed tomography in 89 (79%) patients, nuclear scan in 23 (21%), ultrasound in four (4%), and arteriography in two (2%). There were 28 Class I, 51 Class II, 31 Class III, two Class IV, and no Class V splenic injuries. Nonoperative management was unsuccessful in one (2%) child and 12 (17%) adults (p less than 0.05). Failure was due to ongoing hemorrhage in 12 patients and delayed recognition of pancreatic injury in one patient. Of the 12 patients ultimately requiring laparotomy for control of hemorrhage, seven (58%) were successfully treated with splenic salvage techniques. Overall mortality was 3%; none of the four deaths was due to splenic or associated abdominal injury. This contemporary multicenter experience suggests that patients with Class I, II, or III splenic injuries after blunt trauma are candidates for nonoperative management if there is: 1) no hemodynamic instability after initial fluid resuscitation; 2) no serious associated abdominal organ injury; and 3) no extra-abdominal condition which precludes assessment of the abdomen. Strict adherence to these principles yielded initial nonoperative success in 98% of children and 83% of adults. Application of standard splenic salvage techniques to treat the patients with persistent hemorrhage resulted in ultimate splenic preservation in 100% of children and 93% of adults