Laser Doppler imaging for early detection of hemorrhage.

BACKGROUND: Laser Doppler Imaging (LDI) is a noninvasive means to measure blood flow through the superficial skin capillary plexus using flux units. Our objective was to determine the ability of LDI of the skin to detect and quantify rapid, severe hemorrhage. METHODS: Five Yucatan mini-pigs (25-35 kg) underwent controlled hemorrhage of 25 mL/kg blood for 20 minutes. Median flux of a 10 cm × 10 cm area of the lower abdomen was measured at 2-minute intervals from initiation of hemorrhage to resuscitation with concurrent measurement of heart rate (HR), systolic blood pressure (SBP), and mean arterial pressure (MAP). RESULTS: Average time to a change of 5 U in flux following start of hemorrhage was 2.4 minutes. This was significantly faster than time to change in HR (19.2 minutes, p < 0.05) and showed a trend toward more rapid identification of hemorrhage relative to changes in SBP (3.2 minutes, p = 0.157) and MAP (3.6 minutes, p = 0.083). Flux changes occurred at smaller % total blood volume lost than HR (3.94% vs. 28.8%, p < 0.05) and trended toward smaller volume identification than SBP (4.88%, p = 0.180) and MAP (5.36%, p = 0.102). Average correlation (ρ) of blood volume lost to flux was -0.974; HR, 0.346; SBP, -0.978; and MAP, -0.975. A change of 5 flux units was significantly more sensitive for hemorrhage than a change of 5 beats per minute in HR or 5 mm Hg in SBP or MAP (0.596 vs. 0.169, 0.438, and 0.287 respectively, all p < 0.05). CONCLUSION: LDI is a sensitive, specific, and early means to detect and quantify severe hemorrhage.

Risk factors for traumatic injury findings on thoracic computed tomography among patients with blunt trauma having a normal chest radiograph.

HYPOTHESIS: We sought to identify risk factors that might predict acute traumatic injury findings on thoracic computed tomography (TCT) among patients having a normal initial chest radiograph (CR). DESIGN: In this retrospective analysis, Abbreviated Injury Score cutoffs were chosen to correspond with obvious physical examination findings. Multivariate logistic regression analysis was performed to identify risk factors predicting acute traumatic injury findings. SETTING: Urban level I trauma center. PATIENTS: All patients with blunt trauma having both CR and TCT between July 1, 2005, and June 30, 2007. Patients with abnormalities on their CR were excluded. MAIN OUTCOME MEASURE: Finding of any acute traumatic abnormality on TCT, despite a normal CR. RESULTS: A total of 2435 patients with blunt trauma were identified; 1744 (71.6%) had a normal initial CR, and 394 (22.6%) of these had acute traumatic findings on TCT. Multivariate logistic regression demonstrated that an abdominal Abbreviated Injury Score of 3 or higher (P = .001; odds ratio, 2.6), a pelvic or extremity Abbreviated Injury Score of 2 or higher (P < .001; odds ratio, 2.0), age older than 30 years (P = .004; odds ratio, 1.4), and male sex (P = .04; odds ratio, 1.3) were significantly associated with traumatic findings on TCT. No aortic injuries were diagnosed in patients with a normal CR. Limiting TCT to patients with 1 or more risk factors predicting acute traumatic injury findings would have resulted in reduced radiation exposure and in a cost savings of almost $250,000 over the 2-year period. Limiting TCT to this degree would not have missed any clinically significant vertebral fractures or vascular injuries. CONCLUSION: Among patients with a normal screening CR, reserving TCT for older male patients with abdominal or extremity blunt trauma seems safe and cost-effective.

Epidemiology and risk factors for hospital-acquired methicillin-resistant Staphylococcus aureus among burn patients.

Methicillin-resistant Staphylococcus aureus (MRSA) is a substantial source of morbidity among burn patients. The objectives of this study were to determine the feasibility and efficacy of surveillance cultures and isolation precautions on limiting the transmission of MRSA among burn patients and to determine risk factors for the development of hospital-acquired MRSA (HA-MRSA). All patients admitted to the burn service from January 2007 to June 2009 were screened by nasal swab culture on admission and weekly thereafter. Other sites were cultured based on clinical suspicion. Patients with MRSA were immediately placed on isolation precautions. Community-acquired MRSA (CA-MRSA) and HA-MRSA were defined as identification of the organism <72 hours from admission (CA-MRSA) or ≥72 hours after admission (HA-MRSA). Charts were retrospectively analyzed to identify risk factors for development of HA. Screening compliance was 100%. Seventy MRSA cases were identified in 752 admissions (9% incidence), including 30 cases of CA-MRSA and 40 cases of HA-MRSA. Over the 30-month study period, HA-MRSA incidence decreased according to a significant linear trend. Independent risk factors for the development of HA-MRSA on multivariate analysis included length of stay >7 days (odds ratio [OR] 12.0, 95% confidence interval [CI] 1.6-91), TBSA affected >10% (OR 6.1, CI 2.6-14.2), age >30 years (OR 4.9, CI 2.0-12.0), and inhalation injury (OR 3.5, CI 1.0-11.7). Surveillance cultures with isolation precautions are practical and effective for preventing HA-MRSA among burn patients. Older patients with prolonged hospital stays, large wounds, and inhalation injury are at greatest risk.

A multidisciplinary organ donor council and performance improvement initiative can improve donation outcomes.

The shortage of organs available for transplantation has become a national crisis. The Department of Health and Human Services established performance benchmarks for timely notification, donation after cardiac death (DCD), and conversion rates (total donors/eligible deaths) to guide organ procurement organizations and donor hospitals in their attempts to increase the number of transplantable organs. In January 2007, an organ donor council (ODC) with an ongoing performance improvement case review process was created at a Level I trauma center. A critical care devastating brain injury protocol and a DCD policy were instituted. Best performance benchmarks were evaluated before and after establishment of the ODC. At our center, the total number of referrals increased from 96 in 2006 to 139 in 2007 and 143 in 2008. Timely notification rate increased from 64 per cent in 2006 to 83 per cent in 2007 and 2008 (P < 0.01). DCD rate increased from 0 per cent in 2006 to 13 per cent in 2007 (P = 0.06) and 10 per cent in 2008 (P = 0.09). Conversion rate increased from 53 per cent in 2007 to 78 per cent in 2008 (P = 0.05) and 73 per cent in 2009 (P = 0.16). Organs transplanted per eligible death trended upward from 1.80 in 2007 to 2.54 in 2009 (P = 0.20). As a consequence, the establishment of a multidisciplinary ODC and performance improvement initiative demonstrated improved donation outcomes.

Standard prophylactic enoxaparin dosing leads to inadequate anti-Xa levels and increased deep venous thrombosis rates in critically ill trauma and surgical patients.

BACKGROUND: Deep venous thromboses (DVT) continue to cause significant morbidity in critically ill patients. Standard prophylaxis for high risk patients includes twice-daily dosing with 30 mg enoxaparin. Despite prophylaxis, DVT rates still exceed 10% to 15%. Anti-Xa levels are used to measure the activity of enoxaparin and 12-hour trough levels

Successful management of occult pneumothorax without tube thoracostomy despite positive pressure ventilation.

The objective of this study was to determine whether tube thoracostomy can be safely avoided in a subset of patients with blunt occult pneumothorax. A retrospective review was performed. Management without tube thoracostomy was attempted for 59 occult pneumothoraces and was successful in 51 (86%). Observation was successful in 16 of 20 occult pneumothoraces (80%) exposed to positive pressure ventilation within 72 hours of admission. Eight delayed tube thoracostomies were required an average of 19.7 hours post admission. Patients who failed observant management had more significant physiologic derangement on admission (revised trauma score 6.96 vs 7.66, P = 0.04), were more likely to have significant multisystem trauma (88% vs 37%, P = 0.007), but were not more likely to require positive pressure ventilation (PPV) (50% vs 31%, P = 0.31). This study demonstrates that a subset of patients with blunt occult pneumothorax requiring positive pressure ventilation may be safely managed without tube thoracostomy.

Significant correlation of trauma epidemiology with the economic conditions of a community.

HYPOTHESIS: Depressed economic conditions are associated with increased trauma and violent crime. DESIGN: Retrospective cohort study of prospectively collected data. SETTING AND INTERVENTIONS: Population and labor force data from 1992 to 2002 were obtained from the state Employment Development Department and the US Census Bureau. County data regarding the total number of trauma activations and mechanism of trauma were recorded. Crime statistics were obtained from the state Department of Justice and the Federal Bureau of Investigation. Correlation statistics were performed. Health care coverage for victims of penetrating trauma was also analyzed. MAIN OUTCOME MEASURES: Correlation between unemployment rate, trauma epidemiology, and crime indexes. RESULTS: The correlation between the percentage penetrating trauma and the unemployment rate was R = 0.92 (Orange County, California) and R = 0.95 (Los Angeles County, California) (P<.001). The unemployment rate was also tightly correlated with Federal Bureau of Investigation crime indexes in both counties and in the state (P<.001). The overall county population was positively correlated with the total number of trauma occurrences in both counties (P<.001) but was negatively correlated with the number of penetrating traumas and crime indexes (P<.001). Seventy-five percent of penetrating trauma victims had no health care coverage or had state or county aid only. CONCLUSIONS: The proportion of violent crime in a community is closely associated with the unemployment rate of that community and will vary longitudinally over time. The overall county population is less important. These data may be used for public policy initiatives regarding resource allocation to trauma centers, law enforcement planning, and programs aimed at crime prevention.

Computed tomography angiography validates duplex sonographic evaluation of carotid artery stenosis.

Controversy regarding the optimal preoperative evaluation for patients with carotid arterial stenosis remains controversial. We hypothesized that carotid artery area reduction measured by computed tomography angiography (CTA) would closely correlate with duplex scanning stenosis. This study was undertaken to evaluate the correlation between duplex, CTA, and conventional arteriography in patients undergoing consideration for carotid endarterectomy. Patients undergoing evaluation for carotid artery stenosis who received at least 2 of the diagnostic tests were included in this study (n = 108); 30 patients underwent all 3 imaging modalities. Linear regression analysis was performed to determine correlation coefficients between the 3 different study modalities. Correlation and P values were as follows: CTA area versus CTA diameter, r = 0.82, P < 0.001; CTA area versus duplex stenosis, r = 0.71, P < 0.001; duplex stenosis versus angio diameter, r = 0.68; P = 0.005; CTA diameter versus angio diameter, r = 0.61, P = 005. CTA was able to identify plaque characteristics more readily than duplex or arteriography. CTA was also able to differentiate critical stenosis from occlusion and to settle discrepancies obtained from duplex scanning. CTA is an acceptable alternative method to validate duplex scanning evaluation of carotid artery stenosis. It can accurately measure lumen stenosis, visualize plaque morphology, and is associated with fewer complications than conventional angiography.

Management of traumatic abdominal wall hernia.

Traumatic abdominal wall hernia (TAWH) can occur after blunt trauma and can be classified into low- or high-energy injuries. Low energy injuries occur after impact on a small blunt object. High-energy injuries are sustained during motor vehicle accidents or automobile versus pedestrian accidents. We present six cases of high-energy TAWH cases that were treated at our trauma center. All patients presented with varying degrees of abdominal tenderness with either abdominal skin ecchymosis or abrasions, which made physical examination difficult. CT scan confirmed the hernia in each patient. All six patients had associated injuries that required open repair. The abdominal wall defects were repaired primarily. Three patients (50%) in our series developed a postoperative wound infection or abscess. Review of the literature on low-energy TAWH shows no associated abdominal injuries. In conclusion distinction between low- and high-energy injury is imperative in the management of TAWH. Hernias following low-energy injuries can be repaired after local exploration through an incision overlying the defect. TAWHs following high-energy trauma should undergo exploratory laparotomy through a midline incision. The defect should be repaired primarily and prosthetics avoided because of the high incidence of postoperative infection.

Determinants for successful percutaneous image-guided drainage of intra-abdominal abscess.

HYPOTHESIS: Characteristics of intra-abdominal abscess can be used to predict successful outcome for percutaneous catheter drainage (PCD). METHODS: We performed a multicenter prospective study of patients who had intra-abdominal infections treated with PCD and intravenous antibiotics. Multivariate regression analysis determined predictors of successful outcome. RESULTS: The study included 96 patients (59% men; mean +/- SD age, 48 +/- 17 years; mean +/- SD Acute Physiology and Chronic Health Evaluation II score, 7.4 +/- 4.9). Postoperative abscess was present in 53% of patients. Isolated microorganisms included Bacteroides species (17%), Escherichia coli (17%), Streptococcus species (14%), Enterococcus species (10%), and fungi (11%). Single abscesses were present in 83% of patients. Computed tomographic guidance was used for drainage in 80% of patients, and ultrasound was used in 20%. The duration of abscess drainage was less than 14 days in 64%. Complete resolution of the infection with a single treatment of PCD was achieved in 67 patients (70%), and with a second attempt in 12 (12%). Thirty-three patients (34%) had PCD for the resolution of intra-abdominal sepsis prior to an elective, definitive procedure. Open drainage as a result of PCD failure was required in 15 (16%) and was more likely in patients with yeast (P<.001) or a pancreatic process (P =.02). Postoperative abscess (P =.04) was an independent predictor of successful outcome. CONCLUSIONS: Percutaneous catheter drainage of intra-abdominal infections was effective with a single treatment in 70% of patients and increased to 82% with a second attempt. A successful outcome is most likely with abscesses that are postoperative, not pancreatic, and not infected with yeast. Percutaneous catheter drainage is now a commonly used staging method for the resolution of intra-abdominal sepsis prior to corrective operation.