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We measured D-dimer and plasminogen activator inhibitor-1 (PAI-1) activity in 45 trauma patients to assess their efficacy in predicting the post-traumatic hemostatic perturbations. We found the correlation between D-dimer measured by Simpli Red test and ELISA to be highly significant (p=0.0001). The D-dimer ELISA indicated that the serial changes of D-dimer after trauma were variable. However, the increases of D-dimer were associated with clinical conditions of the patient, such as trauma surgery, infections, or thrombotic complications. A significant correlation was found for D-dimer levels measured by ELISA versus the injury severity score (ISS) in all the trauma patients on day 1 (p=0.0153) and on day 2 (p=0.0495). The PAI-1 activity was increased at admission and showed a progessive decline from day 2 onward, and the correlation for the daily decline of PAI-1 was highly significant (p=0.0001). The PAI-1 activity and plasminogen activator activity showed a significant negative correlation on days 1, 2, and 3. PAI-1 activity correlated moderately with D-dimer level only on day 1 (p=0.0569). Three out of forty-five patients developed thrombotic complications: one patient who died from pulmonary embolism and two patients who developed adult respiratory distress syndrome (ARDS). In summary: 1) PAI-1 activity and D-dimer exhibited contrasting serial changes after trauma. 2) There was also a negative correlation between PAI-1 activity and PA activity. 3) A significant correlation of D-dimer with ISS confirms, as might be anticipated, that there is increased activation of the coagulation mechanism in severe injury, and suggests that D-dimer levels may prove useful to screen for patients at strong risks of thrombotic complications.

Occult pneumothorax is defined as a pneumothorax that is detected by abdominal computed tomographic (CT) scanning, but not routine supine screening chest roentgenograms. Forty trauma patients with occult pneumothorax were prospectively randomized to management with tube thoracostomy (n = 19) or observation (n = 21) without regard to the possible need for positive pressure ventilation, to test the hypothesis that tube thoracostomy is unnecessary in this entity. Eight of the 21 patients observed had progression of their pneumothoraces on positive pressure ventilation, with three developing tension pneumothorax. None of the patients with tube thoracostomy suffered major complications as a result of the procedure. Hospital and ICU lengths of stay were not increased by tube thoracostomy. Patients with occult pneumothorax who require positive pressure ventilation should undergo tube thoracostomy.

This study examined a mesh wrap technique that provides effective hepatic tamponade and clinical experience with the technique in 6 patients is reported. Technical feasibility and effectiveness were investigated in 8 miniature swine. The animals were divided into two groups: group A (n = 4), control animals; stellate liver lacerations without mesh wrap or other measures for hemostasis, and group B (n = 4); stellate liver laceration with synthetic absorbable mesh wrap applied for hepatic hemostasis. Except for mesh application, all variables were held constant for both groups. All animals in the control group died within 20 to 120 minutes (mean: 65 minutes). All animals in group B survived (p = 0.029). The livers were harvested for gross and microscopic examinations. No abscess, bile leak, or hematoma was noted. Clinically, total mesh wrapping was attempted in 6 patients with blunt exsanguinating liver injuries. The technique failed intraoperatively in two patients with juxtacaval lacerations and hepatic vein avulsion injuries. One patient with a bilobar gunshot wound died later of sepsis. In three patients with bursting injuries, the technique successfully controlled bleeding and resulted in long-term survival. In conclusion, the total hepatic mesh wrap (1) is geometrically, technically, and mechanically feasible, (2) was not associated with complications in this series, and (3) can effectively secure hemostasis following parenchymal liver injury.

The thermal-dye indicator dilution technique of measuring extravascular lung water (EVLW- TD ) correlates well with gravimetric measurement of lung water (EVLW- GR ) when no positive-end expiratory pressure (PEEP) is used in both normal and edematous lungs. PEEP is often used to raise arterial oxygen tension in acute respiratory failure. This study was designed to answer the question: Does PEEP have an effect on the accuracy of the EVLW measurement by thermal dye? Sixteen mongrel dogs were anesthetized and intubated. Arterial and PA catheters were placed. They were divided into three groups and ventilated at PEEP levels of 5, 10, or 15 cm H 2 O. Fluids were given to minimize decrease in cardiac output with institution of PEEP. They were maintained for 5 hr with measurement of vital signs made hourly and measurement of blood gases and EVLW-TD made at baseline, 1, 3, and 5 hr. After final measurements, gravimetric determination of EVLW was done. Correlation between EVLW TD and EVLW GR remained good when low levels of PEEP were used. At 5 cm H 2 O PEEP, EVLW TD was 7.5 ± 0.9 and EVLW GR was 5.4 ± .3. At 10 cm H 2 O PEEP, they were 10.0 ± 0.9 and 6.5 ± 0.3. The correlations were 0.87 and 0.97, respectively. However, at 15 cm H 2 O PEEP, EVLW TD was 11.4 ± 1.3 and EVLW GR was 7.5 ± 0.6, with a correlation of only 0.59. The correlation between the two techniques seems to break down with higher levels of PEEP in dogs with normal lungs.

INTRODUCTION Pulmonary edema, or increased lung water, adversely affects gas exchange and pulmonary compliance. Numerous safety factors exist to protect against pulmonary edema and alveolar flooding. The most important of these safety factors is thought to be the lymphatic system, which removes water and protein that filters out of the pulmonary capillaries into the interstitium of the lung [ 131. Controversy has existed with regard to how lymph is propelled through the lymphatic system and cleared from the lungs. Essentially, the question centers on whether extrinsic forces caused by movement of surrounding structures (such as muscles, arteries, heart, or lungs) propels the lymph or whether intrinsic forces (rhythmic contractions of smooth muscle in the lymph vessels) were involved. Hall et al. cannulated lymph vessels throughout the body and discovered that extrinsic forces were minor and superimposed on the major intrinsic pressure waves. This applied everywhere except in the central lymphatic system, where the pressures generated by lung expansion and contraction seemed to be the major force [4]. Respiratory movement has been felt by many to be of primary importance for pulmonary or central lymph flow [7, 11, 12, 151. However, Staub and others have felt that intrinsic forces are the most important [ 12, 141. A relatively recent ventilatory technique, high frequency ventilation (HFV), offers an opportunity to examine the importance of extrinsic respiratory tidal motion on the propulsion of lymph in the pulmonary system [2,3]. High frequency ventilation differs from conventional ventilation by using a much smaller tidal volume (often less than dead space) and higher frequencies. This technique involves minimal bulk flow of air and almost no chest wall motion. High frequency ventilation provides a way to maintain normal blood gases for extended periods of time, while maintaining a decreased or absent tidal movement. We asked the question, does marked reduction of tidal expansion and contraction of the lungs have an effect on the accumulation of EVLW in normal dogs over 48 hr?

High-frequency ventilators (HFV) use increased respiratory rates and decreased tidal volumes to achieve gas exchange similar to conventional mechanical ventilators (CMV). This reverses the relative importance of convection and diffusion to gas exchange. There are currently 3 major types of HFV. They differ from each other in how gas is delivered, how they work, and what physiological effects they have. Conclusions drawn using one type of HFV cannot necessarily be applied to the others. This review examines the different types of HFV as well as the studies that have been conducted using HFV. It stresses the role that HFV may play in the surgical intensive care unit. The one certain indication presently for HFV is in patients with a bronchopleural fistula. It may also be useful as an adjunct to endoscopy and in adult respiratory distress syndrome (ARDS). If the underlying lung disease cannot be reversed (i.e., end-stage fibrotic ARDS), HFV has little to offer.

Nonoperative management of blunt injury to the spleen in adults has been applied with increasing frequency. However, the criteria for nonoperative management are controversial. The purpose of this multi-institutional study was to determine which factors predict successful observation of blunt splenic injury in adults.A total of 1,488 adults (15 years of age) with blunt splenic injury from 27 trauma centers in 1997 were studied through the Multi-institutional Trials Committee of the Eastern Association for the Surgery of Trauma. Statistical analysis was performed with analysis of variance and extended chi2 test. Data are expressed as mean +/- SD; a value of p0.05 was considered significant.A total of 38.5 % of patients went directly to the operating room (group I); 61.5% of patients were admitted with planned nonoperative management. Of the patients admitted with planned observation, 10.8% failed and required laparotomy; 82.1% of patients with an Injury Severity Score (ISS)15 and 46.6% of patients with ISS15 were successfully observed. Frequency of immediate operation correlated with American Association for the Surgery of Trauma (AAST) grades of splenic injury: I (23.9%), II (22.4%), III (38.1%), IV (73.7%), and V (94.9%) (p0.05). Of patients initially managed nonoperatively, the failure rate increased significantly by AAST grade of splenic injury: I (4.8%), II (9.5%), III (19.6%), IV (33.3%), and V (75.0%) (p0.05). A total of 60.9% of the patients failed nonoperative management within 24 hours of admission; 8% failed 9 days or later after injury. Laparotomy was ultimately performed in 19.9% of patients with small hemoperitoneum, 49.4% of patients with moderate hemoperitoneum, and 72.6% of patients with large hemoperitoneum.In this multicenter study, 38.5% of adults with blunt splenic injury went directly to laparotomy. Ultimately, 54.8% of patients were successfully managed nonoperatively; the failure rate of planned observation was 10.8%, with 60.9% of failures occurring in the first 24 hours. Successful nonoperative management was associated with higher blood pressure and hematocrit, and less severe injury based on ISS, Glasgow Coma Scale, grade of splenic injury, and quantity of hemoperitoneum.