Michael Lekawa

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 <or=0.1 IU/mL have been associated with higher rates of DVT in orthopedic patients. We hypothesized that low Anti-Xa levels would be found in critically ill trauma and surgical patients and that low levels would be associated with higher rates of DVT. METHODS All patients on the surgical intensive care unit (ICU) service were prospectively followed. In the absence of contraindications, patients were given prophylactic enoxaparin and anti-Xa levels were drawn after the third dose. Trough levels <or=0.1 IU/mL were considered low. Screening duplex exams were obtained within 48 hours of admission and then weekly. Patients were excluded if they did not receive a duplex, if they had a prior DVT, or if they lacked correctly timed anti-Xa levels. DVT rates and demographic data were compared between patients with low and normal anti-Xa levels. RESULTS Data were complete for 54 patients. Eighty-five percent suffered trauma (Injury Severity Score of 25 +/- 12) and 74% were male. Overall, 27 patients (50%) had low anti-Xa levels. Patients with low anti-Xa levels had significantly more DVTs than those with normal levels (37% vs. 11%, p = 0.026), despite similar age, body mass index, Injury Severity Score, creatinine clearance, high risk injuries, and ICU/ventilator days. CONCLUSION Standard dosing of enoxaparin leads to low anti-Xa levels in half of surgical ICU patients. Low levels are associated with a significant increase in the risk of DVT. These data support future studies using adjusted-dose enoxaparin.

Test characteristics of focused assessment of sonography for trauma for clinically significant abdominal free fluid in pediatric blunt abdominal trauma.

OBJECTIVES Focused assessment of sonography in trauma (FAST) has been shown useful to detect clinically significant hemoperitoneum in adults, but not in children. The objectives were to determine test characteristics for clinically important intraperitoneal free fluid (FF) in pediatric blunt abdominal trauma (BAT) using computed tomography (CT) or surgery as criterion reference and, second, to determine the test characteristics of FAST to detect any amount of intraperitoneal FF as detected by CT. METHODS This was a prospective observational study of consecutive children (0-17 years) who required trauma team activation for BAT and received either CT or laparotomy between 2004 and 2007. Experienced physicians performed and interpreted FAST. Clinically important FF was defined as moderate or greater amount of intraperitoneal FF per the radiologist CT report or surgery. RESULTS The study enrolled 431 patients, excluded 74, and analyzed data on 357. For the first objective, 23 patients had significant hemoperitoneum (22 on CT and one at surgery). Twelve of the 23 had true-positive FAST (sensitivity = 52%; 95% confidence interval [CI] = 31% to 73%). FAST was true negative in 321 of 334 (specificity = 96%; 95% CI = 93% to 98%). Twelve of 25 patients with positive FAST had significant FF on CT (positive predictive value [PPV] = 48%; 95% CI = 28% to 69%). Of 332 patients with negative FAST, 321 had no significant fluid on CT (negative predictive value [NPV] = 97%; 95% CI = 94% to 98%). Positive likelihood ratio (LR) for FF was 13.4 (95% CI = 6.9 to 26.0) while the negative LR was 0.50 (95% CI = 0.32 to 0.76). Accuracy was 93% (333 of 357, 95% CI = 90% to 96%). For the second objective, test characteristics were as follows: sensitivity = 20% (95% CI = 13% to 30%), specificity = 98% (95% CI = 95% to 99%), PPV = 76% (95% CI = 54% to 90%), NPV = 78% (95% CI = 73% to 82%), positive LR = 9.0 (95% CI = 3.7 to 21.8), negative LR = 0.81 (95% CI = 0.7 to 0.9), and accuracy = 78% (277 of 357, 95% CI = 73% to 82%). CONCLUSION In this population of children with BAT, FAST has a low sensitivity for clinically important FF but has high specificity. A positive FAST suggests hemoperitoneum and abdominal injury, while a negative FAST aids little in decision-making.

Which central venous catheters have the highest rate of catheter-associated deep venous thrombosis: a prospective analysis of 2,128 catheter days in the surgical intensive care unit.

BACKGROUND Catheter-associated deep venous thromboses (CADVTs) are a common occurrence in the surgical intensive care unit (SICU), necessitating central venous catheter (CVC) removal and replacement. Previous studies evaluating risk factors for CADVT in SICU patients are limited, and most lack a true denominator of all CVC days. We sought to determine the true incidence of and risk factors for CADVT based on patient characteristics as well as CVC site, type, and duration of insertion. METHODS The following data from all SICU patients in two urban Level I trauma centers were prospectively collected from 2009 to 2012: demographics, risk factors for DVT, CVC site/type/duration, and duplex results. Sites included the subclavian (SC), internal jugular (IJ), arm (for peripherally inserted central catheter [PICC] lines), and femoral. Types included multilumen (ML), introducer/hemodialysis (I/HD), and PICC. High-risk patients received weekly screening duplex examinations and a CADVT was defined as a DVT being detected on duplex with a CVC in place or within 7 days of removal. Rates of CADVT were normalized per 1,000 CVC days, and independent predictors of CADVT were determined using logistic regression. RESULTS Data were complete for 184 patients, 354 CVCs, and 2,128 CVC days. Fifty-nine CADVTs were diagnosed in 28% of patients. Rates of CADVT were 9 per 1,000 catheter days for SC, 61 for IJ (p < 0.01 vs. SC), 27 for arm (p < 0.01), 36 for femoral (p < 0.01), 22 for ML, 57 for I/HD (p < 0.01 vs. ML), and 27 for PICC (p = 0.24). After adjusting for patient risk factors, predictors of CADVT included the IJ and arm sites (odds ratio, 6.0 and 3.0 compared with SC) and the I/HD type (odds ratio, 2.6 compared with ML, all p < 0.05). CONCLUSION The IJ and arm sites and I/HD type are associated with increased CADVT. These data may be used to determine the optimal site and type of CVC for insertion. LEVEL OF EVIDENCE Prognostic/epidemiologic study, level III.

Elevated serum pancreatic enzyme levels after hemorrhagic shock predict organ failure and death.

BACKGROUND Intraluminal pancreatic enzymes have been shown in animal models to be associated with multiple organ failure after hemorrhagic shock, independent of pancreatitis. The translocation of these enzymes into the circulation may serve as a marker of hemorrhagic shock-induced gut ischemia in critically injured trauma patients. We hypothesized that serum amylase and lipase would be significantly elevated in patients presenting in hemorrhagic shock and in those who develop organ failure. METHODS : Review of a prospective database at a level-1 trauma center from 2000 to 2005. Two thousand seven hundred eleven critically injured trauma patients without pancreatic injuries were evaluated for shock (systolic pressure <90 mm Hg in the emergency department), massive transfusion (10 units of packed red blood cells within the first 24 hours), and organ failure (standard criteria for acute pulmonary, cardiovascular, renal, and hepatic system failure were used). Serum levels >2 times the upper limit of normal for amylase (30-130 U/L) and lipase (7-60 U/L) were defined as elevated. Univariate analyses were performed with the Pearsons chi, and binary logistic regression was used to determine significant risk factors for organ failure. Results with a p value <0.05 were considered significant and are reported. RESULTS : Patients with elevated amylase (n = 481, 18%) were more likely to present in shock (16% vs. 8%), require massive transfusion (19% vs. 9%), develop organ failure (34% vs. 16%), and die (23% vs. 13%). Patients with elevated lipase (n = 288, 11%) were more likely to require massive transfusion (18% vs. 10%) and develop organ failure (43% vs. 16%). Independent predictors of organ failure were age (odds ratio [OR] = 1.016), Injury Severity Score (OR = 1.02), massive transfusion (OR = 3.1), elevated amylase (OR = 1.9), and elevated lipase (OR = 3.2). Elevated amylase was also an independent predictor of mortality (OR = 1.3). CONCLUSIONS : Serum levels of pancreatic enzymes are elevated in patients who present in shock or require a massive transfusion and are independent predictors of organ failure. Whether these elevations are caused by ischemic pancreatitis or the translocation of intraluminal enteric pancreatic enzymes is uncertain and future studies are needed. Trauma patients with elevated pancreatic enzymes in the absence of a pancreatic injury have an increased risk of morbidity and mortality.

Ability of a chest X-ray and an abdominal computed tomography scan to identify traumatic thoracic injury

OBJECTIVE Our objective was to show that a chest X-ray (CXR) and an abdominal computed tomography (CT) scan are sufficient to identify most clinically significant thoracic injuries in trauma patients, rendering the thoracic CT scan useful in only a subset of patients. METHODS A retrospective study identified thoracic injuries in 374 trauma patients evaluated with a CXR, a thoracic CT scan, and an abdominal CT scan. Injuries seen on the initial CXR versus those seen on a CT scan only (occult) were identified and assessed for clinical relevance. RESULTS An abdominal CT scan identified 65% (15/23) of occult pneumothoraces, 100% (25/25) of occult hemothoraces, 64% (18/28) of occult pulmonary contusions, and 58% (18/31) of occult rib fractures. No occult pneumothoraces seen on the thoracic CT scan alone required tube thoracostomy. CONCLUSIONS Our pilot study suggests that a CXR and an abdominal CT scan will identify most occult intrathoracic injuries. Reserving a thoracic CT scan for patients with an abnormal CXR or high-risk mechanism could safely reduce cost and radiation exposure while still diagnosing significant thoracic injuries.

Risk factors for venous thromboembolism in critically ill trauma patients who cannot receive chemical prophylaxis

BACKGROUND Standard venous thromboembolism (VTE) prevention for critically ill trauma patients includes sequential compression devices and chemical prophylaxis. When contraindications to anticoagulation are present, prophylactic inferior vena cava filters (IVCF) may be used to prevent pulmonary emboli (PE) in high-risk patients, but specific indications are lacking. We sought to identify independent predictors of VTE in critically-ill trauma patients who cannot receive chemical prophylaxis in order to identify a subset of patients who may benefit from aggressive screening and/or prophylactic IVCF placement. METHODS All trauma patients in the surgical ICU from 2008 to 2009 were prospectively followed. Patients with an ICU length of stay ≥2 days who had contraindications to prophylactic anticoagulation were included. Screening duplex exams were obtained within 48 h of admission and then weekly. CT-angiography for PE was obtained if clinically indicated. Patients were excluded if they did not receive a duplex or if they had a post-injury VTE prior to ICU admission. Data regarding VTE rates (lower extremity [LE] DVT or PE), demographics, past medical history (PMH), injuries, and surgeries were collected. Univariate and multivariable analyses were performed to identify independent predictors of VTE with a p<0.05. RESULTS 411 trauma patients with a mean age of 48 (SD 22) years and 8 (SD 9) ICU days were included. 72% were male and the mean ISS was 22 (SD 13). 30 (7.3%) patients developed VTE: 28 (6.8%) with LEDVT and 2 (0.5%) with PE. Risk factors for VTE with a p<0.2 on univariate analysis included: PMH of DVT, injury severity score (ISS), extremity fractures (Fx), and a pelvis or LE extremity Fx repair. After logistic regression, only PMH of DVT (OR=22.6) and any extremity Fx (OR=2.4) remained as independent predictors. CONCLUSION VTE occur in 7% of critically injured trauma patients who cannot receive chemical prophylaxis. Aggressive screening and/or prophylactic IVCF placement may be considered in patients with a PMH of DVT or extremity fractures when anticoagulation is prohibited.

Implementation of a cost-saving algorithm for pelvic radiographs in blunt trauma patients

BACKGROUND In a previous retrospective study, we demonstrated that pelvic radiographs (PXRs) in the evaluation of blunt trauma patients undergoing abdominal computed tomographic (CT) scanning have limited utility in the absence of hemodynamic instability and significant physical findings. The purpose of this study was to prospectively validate an algorithm defining indications for PXR in blunt trauma patients in the emergency department. METHODS We performed a prospective observational study of consecutive blunt trauma patients over 6 months at a single Level 1 trauma center. The trauma faculty agreed to implement an algorithm of obtaining PXRs in patients undergoing abdominal CT scanning only if a specific set of criteria were met: systolic blood pressure <90 mm Hg, hemoglobin <8 mg/dL, a drop in Hgb of more than 3 mg/dL while in the trauma bay, or significant physical examination findings. The algorithm could be overridden at the discretion of the attending physician. RESULTS Nine hundred ninety-five consecutive blunt trauma patients whose evaluation was to include an abdominal CT scan were included in the study. Only 54 patients (6%) received a PXR. Fifty-six indications for PXR were provided: 35 (63%) severe pelvic pain, 14 (25%) proximal fractures, 3 (5%) hip dislocations, and only 4 (7%) had unexplained hypotension. No adverse events or delays in care occurred such as hypotension in the CT scanner or a delay in contacting interventional radiology, blood transfusion, or application of a pelvic binder. The algorithm selected PXR for patients who were more likely to have a pelvic fracture (33% vs. 4.5%, p < 0.001), hip dislocation (7.4% vs. 0.1%, p < 0.001), femur fracture (22.2% vs. 2.7%, p < 0.001), and to require blood transfusion (11.1% vs. 1.9%, p < 0.001). Implementation of this algorithm resulted in a decrease in charges of >

Risk Factors for Traumatic Injury Findings on Thoracic Computed Tomography Among Patients With Blunt Trauma Having a Normal Chest Radiograph

226,000 in 6 months. CONCLUSION When objective evaluation of the abdomen is to be obtained via CT scanning, PXR in the emergency department is obsolete in the absence of hemodynamic instability and significant physical examination findings. Implementation of a selective algorithm in this patient population can result in significant cost savings without adverse patient outcomes.

Predictors of Hazardous Drinking Behavior in 1,340 Adult Trauma Patients: A Computerized Alcohol Screening and Intervention Study

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

The natural history of upper extremity deep venous thromboses in critically ill surgical and trauma patients: what is the role of anticoagulation?

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.