Michael Moncure

Utility of the shock index in predicting mortality in traumatically injured patients.

BACKGROUND Currently, specific triage criteria, such as blood pressure, respiratory status, Glasgow Coma Scale, and mechanism of injury are used to categorize trauma patients and prioritize emergency department (ED) and trauma team responses. It has been demonstrated in previous literature that an abnormal shock index (SI = heart rate [HR]/systolic blood pressure, >0.9) portends a worse outcome in critically ill patients. Our study looked to evaluate the SI calculated in the field, on arrival to the ED, and the change between field and ED values as a simple and early marker to predict mortality in traumatically injured patients. METHODS A retrospective chart review of the trauma registry of an urban level I trauma center. Analysis of 2,445 patients admitted over 5 years with records in the trauma registry of which 1,166 also had data for the field SI. An increase in SI from the field to the ED was defined as any increase in SI regardless of the level of the magnitude of change. RESULTS Twenty-two percent of patients reviewed had an ED SI >0.9, with a mortality rate of 15.9% compared with 6.3% in patients with a normal ED SI. An increase in SI between the field and ED signaled a mortality rate of 9.3% versus 5.7% for patients with decreasing or unchanged SI. Patients with an increase in SI of >or=0.3 had a mortality rate of 27.6% versus 5.8% for patients with change in SI of <0.3. CONCLUSION Trauma patients with SI >0.9 have higher mortality rates. An increase in SI from the field to the ED may predict higher mortality. The SI may be a valuable addition to other ED triage criteria currently used to activate trauma team responses.

Predictors of operative outcome in patients with human immunodeficiency virus infection and acquired immunodeficiency syndrome

BACKGROUND Plasma viral load has recently been associated with clinical outcome in patients with human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS). We hypothetized that, in addition to CD4 lymphocytes, plasma HIV-1 RNA counts are predictive of postoperative outcome. METHODS HIV-infected and AIDS patients admitted to a major teaching hospital requiring invasive or surgical procedures were retrospectively analyzed for postoperative outcome. Preoperative and postoperative immune cell counts including plasma HIV-1 RNA counts were recorded. Chi-square analysis, Fishers exact test, and multivariate regression were performed with statistical significance P </=0.05. RESULTS Fifty-five consecutive patients between 14 and 62 years of age were admitted in a 1-year period and underwent 64 diagnostic and therapeutic procedures. Fourteen (22%) postoperative infections and 18 (28%) complications other than infection, with an overall mortality of 11%, were documented. Total preoperative white blood cell count ([WBC] P <0.01), preoperative percent lymphocyte count (P <0.01), absolute postoperative CD4 lymphocyte count (P <0.01), and postoperative plasma viral load (P <0.0001) are associated with mortality. Multivariate regression indicated that postoperative percent CD4 lymphocyte count is an independent predictor of both postoperative infection and other complications (P <0.05, R = 0.848, power = 0.9911), while the decrement in percent CD4 lymphocyte count is an independent predictor of postoperative complications other than infection (P <0.05, R = 0.596, power = 0.7838). CONCLUSIONS In accordance with the medical literature for clinical outcome in HIV-infected and AIDS patients, both immune cell counts and HIV-1 RNA counts were found to associate with postoperative mortality. However, the postoperative and decrement in percent CD4 lymphocyte proved to be the independent predictors of postoperative complications.

Adenosine A2A analogue improves neurologic outcome after spinal cord trauma in the rabbit.

BACKGROUND ATL-146e, an adenosine A2A agonist, reduces paralysis after spinal cord ischemia-reperfusion. We hypothesized that systemic ATL-146e could improve neurologic outcome after blunt spinal cord trauma. METHODS Twenty rabbits survived a thoracic spinal cord impact of 30 g-cm. One group received 0.06 microg/kg/min ATL-146e for the first 3 hours after impact (A2A group), whereas a second group received saline carrier (T/C group). Neurologic outcome was measured using the Tarlov scale (0-5). Histologic sections from the A2A and T/C groups were compared for neuronal viability. RESULTS There was significant improvement in Tarlov scores of A2A animals compared with T/C animals at 12 hours (p = 0.007), with a trend toward improvement at 36 (p = 0.08) and 48 (p = 0.09) hours after injury. There was decreased neuronal attrition in A2A animals (p = 0.06). CONCLUSION Systemic ATL-146e given after spinal cord trauma results in improved neurologic outcome. Adenosine A2A agonists may hold promise as a rapidly acting alternative to steroids in the early treatment of the spinal cord injured patient.

Carboxyhemoglobin elevation in trauma victims.

BACKGROUND Products of the hemeoxygenase enzyme include carboxyhemoglobin (COH) and bilirubin, which have protective effects in stressed states. Hemeoxygenase-1 enzyme up-regulates in states of oxidative stress. We hypothesized that COH is elevated in septic trauma patients compared with nonseptic patients. METHODS A prospective study was carried out at a Level I trauma center involving all patients admitted to the trauma intensive care unit. During a 3.5-month period, 45 patients were enrolled, with 76 samples being drawn on admission and at later time points. The samples were classified as septic (Bones criteria), stressed (based on expired gas analysis), or nonstressed nonseptic. Correlations with Acute Physiology and Chronic Health Evaluation III score, white blood cell count, temperature, partial pressure of oxygen, and percentage of inspired oxygen were evaluated. RESULTS COH levels in samples drawn from patients presenting in shock (systolic blood pressure < or =90 mm Hg) were significantly higher than levels in samples from patients not in shock (systolic blood pressure >90 mm Hg) (3.27+/-1.09 vs. 2.75+/-0.64; p = 0.013). Samples from septic patients with infection were associated with significantly higher Injury Severity Scores (34.1+/-11.2 vs. 21.8+/-18.3; p< or =0.05) and a lower percentage of inspired oxygen (41.6+/-10.3 vs. 61.0+/-26.3; p< or =0.05). CONCLUSION COH was significantly elevated in samples drawn during stress, sepsis, and shock states. There was overlap between sepsis and stress COH sample values, limiting the clinical usefulness of the assays in predicting sepsis. Further studies focusing on hemeoxygenase-1 expression and the role of its by-products in the outcomes of trauma patients are warranted.

How Accurate Are Resting Energy Expenditure Prediction Equations in Obese Trauma and Burn Patients

BACKGROUND While the prevalence of obesity continues to increase in our society, outdated resting energy expenditure (REE) prediction equations may overpredict energy requirements in obese patients. Accurate feeding is essential since overfeeding has been demonstrated to adversely affect outcomes. OBJECTIVES The first objective was to compare REE calculated by prediction equations to the measured REE in obese trauma and burn patients. Our hypothesis was that an equation using fat-free mass would give a more accurate prediction. The second objective was to consider the effect of a commonly used injury factor on the predicted REE. METHODS A retrospective chart review was performed on 28 patients. REE was measured using indirect calorimetry and compared with the Harris-Benedict and Cunningham equations, and an equation using type II diabetes as a factor. Statistical analyses used were paired t test, +/-95% confidence interval, and the Bland-Altman method. RESULTS Measured average REE in trauma and burn patients was 21.37 +/- 5.26 and 21.81 +/- 3.35 kcal/kg/d, respectively. Harris-Benedict underpredicted REE in trauma and burn patients to the least extent, while the Cunningham equation underpredicted REE in both populations to the greatest extent. Using an injury factor of 1.2, Cunningham continued to underestimate REE in both populations, while the Harris-Benedict and Diabetic equations overpredicted REE in both populations. CONCLUSIONS The measured average REE is significantly less than current guidelines. This finding suggests that a hypocaloric regimen is worth considering for ICU patients. Also, if an injury factor of 1.2 is incorporated in certain equations, patients may be given too many calories.

Heme-oxygenase-1 mRNA expression affects hemorrhagic shock-induced leukocyte adherence.

BACKGROUND Hemorrhagic shock-related leukocyte adherence to endothelial cells is a key step in microvascular injury-related organ damage. Heme-oxygenase-1 (HO-1) metabolizes heme, a potent cytotoxic agent, to carbon monoxide and biliverdin. We hypothesized that changing HO-1 expression would change leukocyte adherence after hemorrhagic shock. METHODS Rats were administered hemin, zinc protoporphyrin, or vehicle 6 hours before surgery. HO-1 expression was determined by reverse-transcriptase polymerase chain reaction in various tissues. Shock was induced in urethane-anesthetized animals by decreasing mean arterial blood pressure to 40 mm Hg for 60 minutes, followed by standard resuscitation measures. Leukocyte adherence was measured by intravital microscopy in rat mesenteric venules. RESULTS Hemin, hemorrhagic shock, and the combination resulted in significantly increased HO-1 expression, whereas zinc-protoporphyrin (ZNPP) resulted in significantly decreased leukocyte adherence. After hemorrhagic shock and hemin administration, leukocyte adherence was significantly decreased 60 minutes into resuscitation (7.92 +/- 2.29 vs. 4.84 +/- 0.71 cells/100 microm, p < 0.05) and significantly increased after ZNPP plus shock (14.08 +/- 3.95, p <or= 0.01). CONCLUSION The results demonstrate that hemin increases and ZNPP decreases HO-1 mRNA expression and attenuates hemorrhagic shock-induced leukocyte adherence, whereas ZNPP decreases it. These results suggest that by changing HO-1 expression, leukocyte adherence resulting from oxidant injury may be altered.

EFFECT OF LFA-1β ANTIBODY ON LEUKOCYTE ADHERENCE IN RESPONSE TO HEMORRHAGIC SHOCK IN RATS

The activation and adherence of leukocytes to the venular endothelium are critical steps in the pathogenesis of generalized microvascular injury following hemorrhagic shock. Previous studies have shown that the integrins CD11/CD18 play a significant role in this interaction. The purpose of this study is to examine the efficacy of anti-LFA-1β, an antibody to CD11a/CD18, in attenuating leukocyte adherence before, during, and after hemorrhagic shock. Following a control period, blood was withdrawn to reduce the mean arterial pressure to 40 mm Hg for 30 min in urethane-anesthetized rats. Mesenteric venules in a transilluminated segment of the small intestines were examined to quantitate leukocyte adherence using intravital microscopy. In sham-operated rats (control), there was minimal to no leukocyte adherence throughout the experiment. Hemorrhagic shock resulted in significant leukocyte adherence during resuscitation (10.8 ± 1.7 cells/100 μm, P < 0.01) when compared to control. Anti-LFA-1β, when given before hemorrhagic shock, significantly attenuated leukocyte adherence during resuscitation (1.1 ± 0.8, P < 0.01) when compared with hemorrhagic shock alone. This protective effect of anti-LFA-1β on leukocyte adherence was even demonstrated when it was given during (1.6 ± 0.3, P < 0.01) and 10 min after hemorrhagic shock (5.8 ± 0.4, P < 0.05). These results suggest that anti-LFA-1β may be of potential therapeutic benefit against microvascular injury caused by hemorrhagic shock.

Jejunostomy Tube Feedings Should not Be Stopped in the Perioperative Patient

BACKGROUND Anesthetic standard of care is to restrict oral intake for 8 hours before elective surgery. There is no research addressing appropriate preoperative discontinuation of jejunostomy tube (J-tube) feedings. We hypothesized that patients could be fed safely, via a J-tube, until the time of surgery. METHODS Patients admitted to a Level I Trauma Center, having J-tubes and undergoing a nonabdominal operation, were prospectively evaluated. Group I patients received J-tube feedings until transport to the operating room. Group II patients had tube feedings discontinued for at least 8 hours before surgery. Data were compared using the Students t test and contingency table analysis. RESULTS There were 46 patients in group I and 36 in group II. There was no incidence of aspiration. Patient groups did not differ in age, mortality, length of stay, injury severity score, or ventilator days. Group I patients had tube feedings discontinued for fewer hours before and after surgery than group II patients (before surgery: 1.40 +/- 1.20 vs 11.61 +/- 5.01, respectively; p < .001; after surgery: 2.99 +/- 7.49 vs 7.11 +/- 9.03, respectively; p = .043); received more kilocalories/ grams of protein on the day of surgery (group I vs group II, 1676.15/89.57 +/- 1133.21/38.04 vs 791.14/57.58 +/-498.66/79.87, respectively; p = .001/p = .032) and more kilocalories/grams of protein on the first postoperative day (group I vs group II, 1580.74/92.57 +/- 600.53/37.96 vs 1152.47/63.53 +/- 733.96/39.40, respectively; p = .006/p = .001). CONCLUSIONS Patients receiving J-tubes who are undergoing nonabdominal operations may safely continue enteral nutrition at maximum protein and caloric intake until surgery.

Implementation and Enforcement of Ventilator-Associated Pneumonia Prevention Strategies in Trauma Patients

BACKGROUND We hypothesized that strict enforcement of ventilator-associated pneumonia (VAP) prevention (VAPP) strategies would decrease the incidence of VAP and improve patient outcomes. METHODS This retrospective study examined 696 consecutive ventilated patients in a Level One trauma center. Three study groups were compared: Pre-VAPP, VAPP implementation, and VAPP enforcement. Ventilator days were compared with occurrences of VAP, defined by the U.S. Centers for Disease Control and Prevention National Nosocomial Infection Surveillance criteria. Patients with and without VAP were compared to evaluate the effect of VAP on patient outcome. Fisher exact, Kruskal-Wallis, and chi-square analyses were used, and p < 0.05 was considered significant. RESULTS During the pre-VAPP protocol period, 5.2 cases of VAP occurred per 1,000 days of ventilator support. The number of cases of VAP decreased to 2.4/1,000 days (p = 0.172) and 1.2/1,000 days (p = 0.085) in the implementation and enforcement periods, respectively. However, when including all trauma patients, regardless of head Abbreviated Injury Score (AIS) score, the difference in the rate of VAP was statistically significant in the enforcement period, but not in the implementation period, compared with the pre-VAPP period (p = 0.014 and 0.062, respectively). A significant decrease was seen in the mortality rate (p = 0.024), total hospital days (p = 0.007), intensive care unit days (p = 0.002), ventilator days (p = 0.002), and hospital charges (p = 0.03) in patients without VAP compared with patients having VAP. CONCLUSIONS There was a statistically significant decrease in the occurrence of VAP with strict enforcement of a VAPP protocol, regardless of head AIS score. Although the difference in patients with a head AIS score <3 was not statistically significant, it was clinically meaningful, decreasing the already-low rate of VAP by half. Strict enforcement of VAPP protocols may be cost efficient for hospitals and prevent decreased reimbursement under the Medicare pay-for-performance strategies.

Rapid Emergency Medicine Score (REMS) in the trauma population: a retrospective study

Objective Rapid Emergency Medicine Score (REMS) is an attenuated version of the Acute Physiology and Chronic Health Evaluation (APACHE) II score and has utility in predicting mortality in non-surgical patients, but has yet to be tested among the trauma population. The objective was to evaluate REMS as a risk stratification tool for predicting in-hospital mortality in traumatically injured patients and to compare REMS accuracy in predicting mortality to existing trauma scores, including the Revised Trauma Score (RTS), Injury Severity Score (ISS) and Shock Index (SI). Design and setting Retrospective chart review of the trauma registry from an urban academic American College of Surgeons (ACS) level 1 trauma centre. Participants 3680 patients with trauma aged 14 years and older admitted to the hospital over a 4-year period. Patients transferred from other hospitals were excluded from the study as were those who suffered from burn or drowning-related injuries. Patients with vital sign documentation insufficient to calculate an REMS score were also excluded. Primary outcome measures The predictive ability of REMS was evaluated using ORs for in-hospital mortality. The discriminate power of REMS, RTS, ISS and SI was compared using the area under the receiver operating characteristic curve. Results Higher REMS was associated with increased mortality (p<0.0001). An increase of 1 point in the 26-point REMS scale was associated with an OR of 1.51 for in-hospital death (95% CI 1.45 to 1.58). REMS (area under the curve (AUC) 0.91±0.02) was found to be similar to RTS (AUC 0.89±0.04) and superior to ISS (AUC 0.87±0.01) and SI (AUC 0.55±0.31) in predicting in-hospital mortality. Conclusions In the trauma population, REMS appears to be a simple, accurate predictor of in-hospital mortality. While REMS performed similarly to RTS in predicting mortality, it did outperform other traditionally used trauma scoring systems, specifically ISS and SI.