Sherry M. Melton

The relationship of blood product ratio to mortality: survival benefit or survival bias?

BACKGROUND Recent studies show an apparent survival advantage associated with the administration of higher cumulative ratios of fresh frozen plasma (FFP) to packed red blood cells (PRBC). It remains unclear how temporal factors and survival bias may influence these results. The objective of this study was to evaluate the temporal relationship between blood product ratios and mortality in massively transfused trauma patients. METHODS Patients requiring massive transfusion (>10 units of PRBC within 24 hours of admission) between 2005 and 2007 were identified (n = 134). In-hospital mortality was compared between patients receiving high (>1:2) versus low (<1:2) FFP:PRBC ratios with a regression model, using the FFP:PRBC ratio as a fixed value at 24 hours (method I) and as a time-varying covariate (method II). RESULTS The FFP:PRBC ratio for all patients was low early and increased over time. Sixty-eight percent of total blood products were given and 54% of deaths occurred during the first 6 hours. Using method I, patients receiving a high FFP:PRBC ratio (mean, 1:1.3) by 24 hours had a 63% lower risk of death (RR, 0.37; 95% CI, 0.22-0.64) compared with those receiving a low ratio (mean, 1:3.7). However, this association was no longer statistically significant (RR, 0.84; 95% CI, 0.47-1.50) when the timing of component product transfusion was taken into account (method II). CONCLUSIONS Similar to previous studies, an association between higher FFP:PRBC ratios at 24 hours and improved survival was observed. However, after adjustment for survival bias in the analysis, the association was no longer statistically significant. Prospective trials are necessary to evaluate whether hemostatic resuscitation is clinically beneficial.

Prospective study of blunt aortic injury: helical CT is diagnostic and antihypertensive therapy reduces rupture.

OBJECTIVE There were two aims of this study. The first was to evaluate the application of helical computed tomography of the thorax (HCTT) for the diagnosis of blunt aortic injury (BAI). The second was to evaluate the efficacy of beta-blockers with or without nitroprusside in preventing aortic rupture. SUMMARY BACKGROUND DATA Aortography has been the standard for diagnosing BAI for the past 4 decades. Conventional chest CT has not proven to be of significant value. Helical CT scanning is faster and has higher resolution than conventional CT. Retrospective studies have suggested the efficacy of antihypertensives in preventing aortic rupture. METHODS A prospective study comparing HCTT to aortography in the diagnosis of BAI was performed. A protocol of beta-blockers with or without nitroprusside was also examined for efficacy in preventing rupture before aortic repair and in allowing delayed repair in patients with significant associated injuries. RESULTS Over a period of 4 years, 494 patients were studied. BAI was diagnosed in 71 patients. Sensitivity was 100% for HCTT versus 92% for aortography. Specificity was 83% for HCTT versus 99% for aortography. Accuracy was 86% for HCTT versus 97% for aortography. Positive predictive value was 50% for HCTT versus 97% for aortography. Negative predictive value was 100% for HCTT versus 97% for aortography. No patient had spontaneous rupture in this study. CONCLUSIONS HCTT is sensitive for diagnosing intimal injuries and pseudoaneurysms. Patients without direct HCTT evidence of BAI require no further evaluation. Aortography can be reserved for indeterminate HCTT scans. Early diagnosis with HCTT and presumptive treatment with the antihypertensive regimen eliminated in-hospital aortic rupture.

Utility of Gram's stain and efficacy of quantitative cultures for posttraumatic pneumonia: a prospective study.

OBJECTIVE This prospective trial examined the efficacy of using bronchoalveolar lavage (BAL) for the diagnosis of pneumonia (PN) and the utility of Grams stain (GS) for dictating empiric therapy. SUMMARY BACKGROUND DATA Posttraumatic nosocomial PN remains a significant cause of morbidity and mortality. However, its diagnosis is elusive, especially in multiply injured patients. The systemic inflammatory response syndrome of fever, leukocytosis, and a hyperdynamic state is common in trauma patients, especially patients with pulmonary contusion. Bronchoscopy with BAL with quantitative cultures of the lavage effluent may distinguish between PN and systemic inflammatory response syndrome, and GS of the lavage effluent may guide empiric therapy before quantitative culture results. METHODS Mechanically ventilated trauma patients with a clinical diagnosis of PN (fever, leukocytosis, purulent sputum, and new or changing infiltrate on chest radiograph) underwent bronchoscopy with BAL. Effluent was sent for GS and quantitative cultures. The diagnostic threshold for PN was > or =10(5) colony-forming units (CFU)/mL, and antibiotics were continued. Antibiotics were stopped for < 10(5) CFU/mL and the diagnosis of systemic inflammatory response syndrome was made. Causative organisms for PN were compared to GS. RESULTS Over a 2-year period, 232 patients underwent 443 bronchoscopies with BAL (71% men, 29% women; mean age, 41). The mean injury severity score was 30. Sixty percent of the patients had pulmonary contusion, and 59% were cigarette smokers. The overall incidence of PN was 39% and was no different regardless of the number of BALs a patient had. The false-negative rate of BAL was 7%. GS identified gram-positive organisms in 80% of patients with gram-positive PN and 40% of patients with gram-negative PN. GS identified gram-negative organisms in 52% of patients with gram-positive PN and 77% with gram-negative PN. The duration of the intensive care unit stay relative to the timing of BAL was beneficial for guiding empiric therapy. BAL in week 1 primarily identified Haemophilus influenzae and gram-positive organisms; Acinetobacter sp. and Pseudomonas sp. were more common after week 1. CONCLUSIONS Bronchoscopy with BAL is an effective method to diagnose PN and avoids prolonged, unnecessary antibiotic therapy. Empiric therapy should be adjusted to the duration of the intensive care unit stay because the causative bacteria flora changes over time. GS of BAL effluent correlates poorly with quantitative cultures and is not reliable for dictating empiric therapy.

Early Versus Delayed Feeding with an Immune-Enhancing Diet in Patients with Severe Head Injuries

BACKGROUND Although early enteral feeding clearly reduces septic morbidity after blunt and penetrating trauma, data for head-injured patients are conflicting. This study examines the effects of early vs delayed enteral feedings on outcome in patients with severe closed-head injuries with a Glasgow Coma Scale (GCS) score greater than 3 and less than 11. METHODS Thirty patients were prospectively randomized to receive an immune-enhancing diet (Impact with fiber) early (initiated < 72 hours after trauma) delivered via an endoscopically placed nasoenteric tube (Stay-Put) or late (administered after gastric ileus resolved). This formula was continued for 14 days or until the patient tolerated oral feeding. Goal rate of nutrition was 21 nonprotein cal/kg/d and 0.3 g N/kg/d. RESULTS Two patients in the early group were excluded due to inability to place the tube, and one patient in the late group died before 72 hours. Five of the remaining 27 died, 1 in the early group and 4 in the late group. There were no significant differences between the groups in length of stay, intensive care unit (ICU) days, significant infection, or GCS score. However, major infection correlated inversely with admission GCS score (R = -0.6, p < .003). Time to reach a GCS score of 14 was significantly longer in patients with significant infections compared with those without (p < .02). CONCLUSIONS No difference in length of stay or infectious complications is shown in patients with severe closed-head injury when they are given early vs delayed feeding using an immune-enhancing formula. Severity of the head injury is closely associated with significant infection.

Age-related gender differential in outcome after blunt or penetrating trauma

Although laboratory studies indicate that female rodents better tolerate the deleterious consequences of trauma and have higher survival rates than male rodents, it remains unclear whether a similar gender dimorphic pattern is evident in humans. In view of this, the association between gender and mortality in trauma patients admitted to a University Level I Trauma Center was assessed. All adult patients admitted to the University of Alabama at Birmingham Trauma Center with blunt or penetrating injury between July 1996 and March 2001 were selected for analysis. Patients were categorized by mechanism (blunt or penetrating), and odds ratios (ORs) were used to compare the risk of death among males compared with females. The ORs were stratified according to age and were adjusted for demographic, medical, and injury characteristics. Male blunt trauma patients <50 years old had a 2.5 times (95% CI 1.3–4.9) higher risk of death than females; however, for those ≥50 years old, a smaller, nonstatistically significant difference was apparent (OR 1.4, 95% CI 0.8–2.3). Conversely, for penetrating trauma, males <50 years old exhibited an increased yet nonsignificant risk of death (OR 1.8, 95% CI 0.6–5.4), whereas those ≥50 years old had a survival advantage (OR 0.1, 95% CI 0.02–0.5). Laboratory studies have demonstrated that estrogens are salutary and androgens are detrimental for survival following trauma-hemorrhage. The results of this study suggest that the physiologic pattern of premenopausal adult female sex hormones may provide a survival advantage in blunt trauma patients; however, the converse pattern prevails for the penetrating trauma patients.

Prognostic value of blood lactate, base deficit, and oxygen-derived variables in an LD50 model of penetrating trauma

OBJECTIVE To determine whether blood lactate, base deficit, or oxygen-derived hemodynamic variables correlate with morbidity and mortality rates in a clinically-relevant LD50 model of penetrating trauma. DESIGN Prospective, controlled study. SETTING University research laboratory. SUBJECTS Anesthetized, mechanically-ventilated mongrel pigs (30+/-2 kg, n = 29). INTERVENTIONS A captive bolt gun delivered a penetrating injury to the thigh, followed immediately by a 40% to 60% hemorrhage. After 1 hr, shed blood and supplemental crystalloid were administered for resuscitation. MEASUREMENTS AND MAIN RESULTS After penetrating injury, 50.7+/-0.3% hemorrhage (range 50% to 52.5%), and a 1-hr shock period, seven of 14 animals died, compared with six of six animals after 55% to 60% hemorrhage, and 0 of nine animals after < or =47.5% hemorrhage. Only two of 13 deaths occurred during fluid resuscitation. At the LD50 hemorrhage, peak lactate concentration and base deficit were 11.2+/-0.8 mM and 9.3+/-1.5 mmol/L, respectively, and minimum mixed venous oxygen saturation, systemic oxygen delivery, and systemic oxygen consumption were 33+/-5%, 380+/-83 mL/min/kg, and 177+/-35 mL/min/kg, respectively. For comparison, baseline preinjury values were 1.6+/-0.1 mM, -6.7+/-0.6 mmol/L, 71+/-3%, 2189+/-198 mL/min/kg, and 628+/-102 mL/min/kg, respectively. Of all the variables, only lactate was significantly related to blood loss before and after fluid resuscitation in the 16 survivors. However, r2 values were relatively low (.20 to .50), which indicates that only a small fraction of the hyperiactacidemia was directly related to tissue hypoperfusion. In the whole population of survivors and nonsurvivors, both lactate and base deficit (but none of the oxygen-derived variables) correlated with blood loss. CONCLUSIONS Arterial lactate is a stronger index of blood loss after penetrating trauma than base deficit or oxygen-derived hemodynamic variables. The reliability of arterial lactate depends on several factors, such as the time after injury, the proportion of survivors and nonsurvivors in the study population, and on factors other than tissue hypoxia.

Duration of red cell storage influences mortality after trauma.

BACKGROUND Although previous studies have identified an association between the transfusion of relatively older red blood cells (RBCs) (storage ≥ 14 days) and adverse outcomes, they are difficult to interpret because the majority of patients received a combination of old and fresh RBC units. To overcome this limitation, we compared in-hospital mortality among patients who received exclusively old versus fresh RBC units during the first 24 hours of hospitalization. METHODS Patients admitted to a Level I trauma center between January 2000 and May 2009 who received ≥ 1 unit of exclusively old (≥ 14 days) vs. fresh (< 14 days) RBCs during the first 24 hours of hospitalization were identified. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated for the association between mortality and RBC age, adjusted for patient age, Injury Severity Score, gender, receipt of fresh frozen plasma or platelets, RBC volume, brain injury, and injury mechanism (blunt or penetrating). RESULTS One thousand six hundred forty-seven patients met the study inclusion criteria. Among patients who were transfused 1 or 2 RBC units, no difference in mortality with respect to RBC age was identified (adjusted RR, 0.97; 95% CI, 0.72-1.32). Among patients who were transfused 3 or more RBC units, receipt of old versus fresh RBCs was associated with a significantly increased risk of mortality, with an adjusted RR of 1.57 (95% CI, 1.14-2.15). No difference was observed concerning the mean number of old versus fresh units transfused to patients who received 3 or more units (6.05 vs. 5.47, respectively; p = 0.11). CONCLUSION In trauma patients undergoing transfusion of 3 or more RBC units within 24 hour of hospital arrival, receipt of relatively older blood was associated with a significantly increased mortality risk. Reservation of relatively fresh RBC units for the acutely injured may be advisable.

Long-term survival in the elderly after trauma.

BACKGROUND In the elderly, trauma has been associated with increased, long-term, all-cause mortality. Functional limitations secondary to injury may be responsible for the reduced survival rate. The objective of this study was to test this hypothesis using data from the Longitudinal Study of Aging (LSOA). METHODS The LSOA is an extension of the 1984 National Health Interview Survey, which focused on 7,527 persons who were 70 years and older in 1984. Using data from the LSOA, a cohort of elderly patients hospitalized for injury in 1985 (N = 102) was identified from Medicare hospital discharge data. An uninjured cohort (N = 408) was also identified using the LSOA and matched by age (within 1 year) and sex. Deaths in both cohorts were identified using the National Death Index. Hazard ratios (HRs) for mortality within 6 years subsequent to injury, adjusted for demographic, health status, and functional characteristics, were calculated. RESULTS The injured cohort had a significantly reduced rate of survival compared with the uninjured cohort (HR = 1.5; 95% confidence interval [CI] 1.1-2.2), and this relationship persisted after adjusting for demographic and health characteristics (HR = 1.4; 95% CI 1.0-2.0). After additional adjustment for measures of functional decline, the association diminished (HR = 1.2; 95% CI 0.8-1.7). Functional decline remained a strong, independent factor for the risk of mortality. CONCLUSION Trauma in the elderly has both an acute and long-term influence on mortality; the latter seems to be mediated through a decline in function resulting from the injury. This study suggests that strategies to return the elderly patient to preinjury functional status are of paramount importance. Future research should explore the impact of these interventions on long-term survival.

Popliteal artery trauma. Systemic anticoagulation and intraoperative thrombolysis improves limb salvage.

OBJECTIVE This study was conducted to evaluate those factors associated with popliteal artery injury that influence amputation, with emphasis placed on those that the surgeon can control. SUMMARY BACKGROUND DATA Generally accepted factors impacting amputation after popliteal artery injury include blunt trauma, prolonged ischemic times, musculoskeletal injuries, and venous disruption. Amputation ultimately results from microvascular thrombosis and subsequent tissue necrosis, predisposed by the paucity of collaterals around the knee. METHODS Patients with popliteal artery injuries over the 10-year period ending November 1995 were identified from the trauma registry. Preoperative (demographics, mechanism and severity of injury, vascular examination, ischemic times) and operative (methods of arterial repair, venous repair-ligation, anticoagulation-thrombolytic therapy, fasciotomy) variables were studied. Severity of extremity injury was quantitated by the Mangled Extremity Severity Score (MESS). Amputations were classified as primary (no attempt at vascular repair) or secondary (after vascular repair). After univariate analysis, logistic regression analysis was performed to identify the independent risk factors for limb loss. RESULTS One hundred two patients were identified; 88 (86%) were males and 14 (14%) were females. Forty injuries resulted from blunt and 62 from penetrating trauma. There were 25 amputations (25%; 11 primary and 14 secondary). Patients with totally ischemic extremities (no palpable or Doppler pulse) more likely were to be amputated (31% vs. 13%; p < 0.04). All requiring primary amputations had severe soft tissue injury and three had posterior tibial nerve transection; the average MESS was 7.6. Logistic regression analysis identified independent factors associated with secondary amputation: blunt injury (p = 0.06), vein injury (p = 0.06), MESS (p = 0.0001), heparin-urokinase therapy (p = 0.05). There were no complications with either heparin or urokinase. CONCLUSIONS Minimizing ischemia is an important factor in maximizing limb salvage. Severity of limb injury, as measured by the MESS, is highly predictive of amputation. Intraoperative use of systemic heparin or local urokinase or both was the only directly controllable factor associated with limb salvage. The authors recommend the use of these agents to maximize limb salvage in association with repair of popliteal artery injuries.

Management of colon wounds in the setting of damage control laparotomy: a cautionary tale.

BACKGROUND Although colon wounds are commonly treated in the setting of damage control laparotomy (DCL), a paucity of data exist to guide management. The purpose of this study was to evaluate our experience with the management of colonic wounds in the context of DCL, using colonic wound outcomes after routine, single laparotomy (SL) as a benchmark. METHODS Consecutive patients during a 7-year period with full-thickness or devitalizing colon injury were identified. Early deaths (<48 hour) were excluded. Colon-related complications (abscess, suture or staple leak, and stomal ischemia) were compared between those managed in the setting of DCL versus those managed by SL, both overall and as stratified by procedure (primary repair, resection and anastomosis, and resection and colostomy). RESULTS One hundred fifty-seven patients met study criteria: 101 had undergone SL and 56 had undergone DCL. Comparison of DCL patients with SL patients was notable for a significant difference in colon-related complications (30% vs. 12%, p < 0.005) and suture/staple leak in particular (12% vs. 3%, p < 0.05). Stratification by procedure revealed a significant difference in colon-related complications among those that underwent resection and anastomosis (DCL: 39% vs. SL: 18%, p < 0.05), whereas no differences were observed in those who underwent primary repair or resection and colostomy. CONCLUSIONS Management of colonic wounds in the setting of DCL is associated with a relatively high incidence of complications. The excessive incidence of leak overall and morbidity particular to resection and anastomosis, however, give us pause. Although stoma construction is not without its own complications in the setting of DCL, it may be the safer alternative.