Evaluating the effects of hypoxic storage on platelet function and health using a novel storage system.

BACKGROUND: Thousands of units of whole blood (WB) and blood components are transfused daily to treat trauma patients. Improved methods for blood storage are critical to support trauma-related care. The Hemanext ONE® system offers a unique method for hypoxic storage of WB, with successfully demonstrated storage of clinically viable RBCs. This work evaluated the system for the storage of WB, focusing on platelet health and function. STUDY DESIGN AND METHODS: WB was collected from healthy donors and processed through the Hemanext ONE® system. Hemoglobin oxygen saturation (HbSO2) levels of WB were depleted to 10%, 20%, or 30% of total HbSO2 and then stored in PVC bags sealed in oxygen-impermeable bags (except for normoxic control) with samples collected on days 1, 7, and 14 post-processing. Flow cytometry assessed the activation and apoptosis of platelets. Clot dynamics were assessed based on aggregometry and thromboelastography assays, as well as thrombin generation using a calibrated-automated thrombogram method. RESULTS: Hypoxic storage conditions were maintained throughout the storage period. Hypoxia triggered increased lactate production, but pH changes were negligible compared to normoxic control. Storage at 10% HbSO2 had a significant impact on platelet function, resulting in increased activation and reduced clot formation and aggregation. These effects were less significant at 20% and 30% HbSO2. DISCUSSION: This study indicates that platelets are sensitive to hypoxic storage and suffer significant metabolic and functional deterioration when stored at or below 10% HbSO2.

Role of the emergency medicine physician in airway management of the trauma patient.

BACKGROUND: A Level I trauma center recently underwent a policy change wherein airway management of the trauma patient is under the auspices of Emergency Medicine (EM) rather than Anesthesiology. METHODS: We prospectively collected data on 11 months of EM intubations (EMI) since this policy change and compared them to the last year of Anesthesia-managed intubations (ANI) to answer the following questions: (1) Is intubation of trauma patients being accomplished effectively by EM? (2) Has there been a change in complication rates since the policy change? (3) How does the complication rate at our trauma center compare with other institutions? RESULTS: EM residents successfully intubated trauma patients on their first attempt 73.7% of the time compared with 77.2% ANI. The overall success rates, i.e., securing the airway within three attempts, were 97.0% (EMI) and 98.0% (ANI). The airway was successfully secured by EMI 100% of the time while a surgical airway was performed in two ANIs. CONCLUSION: EM residents and staff can safely manage the airway of trauma patients. There is no statistically significant difference in peri-intubation complications. The complication rate for EDI (33%) and ANI (38%) is higher than reported in the literature, although the populations are not entirely comparable.

Implications of the "contrast blush" finding on computed tomographic scan of the spleen in trauma.

BACKGROUND: The "contrast blush" (CB) computed tomographic (CT) scan finding has often been used clinically as an indicator for therapeutic splenic intervention (SI) (splenectomy, splenorrhaphy, or angiographic embolization). We sought to examine the prognostic significance of this finding. METHODS: The records and CT scans of 324 trauma patients from two Level I trauma centers who had blunt splenic injury and a CT scan of the abdomen within 24 hours of admission were reviewed and screened for CB. RESULTS: CB was identified in 11% of patients, and its incidence was significantly related to the grade of injury: grade I/II, 3.2%; grade III, 11.8%; and grade IV/V, 26.3% (p < 0.001). SI was also related to the grade: grade I/II, 7.7%; grade III, 37.6%; and grade IV/V, 69.7% (p < 0.001). The chance of having SI was greater in those with CB (75.0%) when compared with those without CB (25.0%) (p < 0.001; odds ratio, 9.2). A multivariate logistic regression analysis revealed that SI correlated independently with splenic grade, emergency department hypotension, and age, but did not demonstrate a correlation with CB. CONCLUSION: CB is not an absolute indication for an operative or angiographic intervention. Factors such as patient age, grade of injury, and presence of hypotension need to be considered in the clinical management of these patients.

Efficacy of thoracic computerized tomography in blunt chest trauma.

Studies suggest that thoracic computed tomography (TCT) is superior to plain chest X-ray (CXR) in the detection of blunt chest injury. This study examined whether TCT provides additional information to routine CXR findings, whether the additional information results in a management change, and whether TCT is more useful in patients with particular mechanisms of injury. Level I trauma patients were prospectively placed into two groups. Control (CTL) group patients underwent TCT as a result of either clinical chest symptoms or abnormal CXR findings. The mechanism (MECH) group contained patients who had no thoracic signs and a negative CXR but experienced severe mechanisms of injury. TCT identified injuries not seen on CXR in 66 per cent of the CTL group and 39 per cent of the MECH group. Identification of these injuries resulted in a highly significant (P < 0.001) change in clinical management in 20 per cent of the CTL group and 5 per cent of the MECH group. TCT appears to be most helpful in the acute evaluation of trauma patients when roentgenographic evidence of chest injury exists and provides additional information impacting on the care of the patient 20 per cent of the time. In patients with severe mechanisms of injury and normal CXRs TCT expeditiously identifies occult chest injuries that require treatment in 5 per cent of this population.

Neutrophil accumulation and damage to the gastric mucosa in resuscitated hemorrhagic shock is independent of inducible nitric oxide synthase.

Polymorphonuclear leukocytes (PMN) and inducible nitric oxide synthase (iNOS) appear to play important roles in the liver and in lung injury induced by hemorrhagic shock. Their precise roles in hemorrhagic shock-induced acute gastric mucosal lesions (AGML), however, are still poorly understood. In this study, we investigated the effect of neutropenia on hemorrhagic shock-induced AGML. We also examined the roles of iNOS in PMN infiltration into the mucosa and AGML during hemorrhagic shock by using L-N6-(1-iminoethyl)-lysine, a potent inhibitor of iNOS, and by reverse transcriptase polymerase chain reaction. Remarkable gastric mucosal damage occurs after hemorrhagic shock. PMN depletion caused by Vinblastine pretreatment significantly attenuates this AGML. Although low-dose L-N6-(1-iminoethyl)-lysine (50 microg/kg, iNOS inhibition) has no effect on AGML, high-dose L-N6-(1-iminoethyl)-lysine (250 microg/kg, iNOS + endothelial NOS inhibition) significantly exacerbates AGML without increasing PMN infiltration into the mucosa. The mRNA expression of iNOS in the stomach during hemorrhagic shock cannot be detected by reverse transcriptase polymerase chain reaction. We conclude that PMN play a pivotal role in hemorrhagic shock-induced AGML, iNOS does not regulate PMN infiltration into the mucosa, and endothelial NOS provides important protection against AGML during hemorrhagic shock.

Interleukin-6 production in hemorrhagic shock is accompanied by neutrophil recruitment and lung injury.

Hemorrhagic shock (HS) initiates an inflammatory cascade that includes the production of cytokines and recruitment of neutrophils (PMN) and may progress to organ failure, inducing acute respiratory distress syndrome (ARDS). To examine the hypothesis that interleukin-6 (IL-6) contributes to PMN infiltration and lung damage in HS, we examined the lungs of rats subjected to unresuscitated and resuscitated HS for the production of IL-6 and activation of Stat3. Using semiquantitative RT-PCR, we found a striking increase in IL-6 mRNA levels only in resuscitated HS, with peak levels observed 1 h after initiation of resuscitation. Increased IL-6 protein expression was localized to bronchial and alveolar cells. Electrophoretic mobility shift assay of protein extracts from shock lungs exhibited an increase in Stat3 activation with kinetics similar to IL-6 mRNA. In situ DNA binding assay determined Stat3 activation predominantly within alveoli. Intratracheal instillation of IL-6 alone into normal rats resulted in PMN infiltration into lung interstitium and alveoli, marked elevation of bronchoalveolar lavage cellularity, and increased wet-to-dry ratio. These findings indicate that IL-6 production and Stat3 activation occur early in HS and may contribute to PMN-mediated lung injury, including ARDS after HS.

A role of neutrophils in the down-regulation of IL-6 and CD14 following hemorrhagic shock.

Hemorrhagic shock (HS) followed by resuscitation has been shown to initiate a series of events, including local cytokine production and PMN accumulation. To determine whether PMN are involved in the regulation of IL-6 expression in the liver or lungs, IL-6 mRNA levels were measured in rats made neutropenic by vinblastine pretreatment prior to HS. IL-6 mRNA levels were determined at 4 or 24 h following resuscitation from shock. Vinblastine alone in normal rats or sham-treated rats had no effect at 4 or 24 h. Vinblastine pretreatment had no effect on the HS-induced increase in IL-6 mRNA at 4 h but dramatically increased levels in both liver and lung at 24 h. Peripheral PMN counts were reduced by 95% in all vinblastine-treated animals. Similar changes seen in CD14 mRNA expression indicate that these effects are not limited to IL-6. These data show that normal PMN levels are not needed for induction of IL-6 and CD14 in HS, and suggest that PMN accumulation down-regulates the expression of these genes.

Asymptomatic aortic stenosis and unexpected death in the trauma patient.

We report the cases of two young trauma patients with asymptomatic aortic stenosis who died after nonlethal blunt traumatic injuries. In both cases, their deaths were attributed to their underlying valvular disease. Awareness of the incidence of asymptomatic aortic stenosis and its potential physiologic hazard to the trauma victim may facilitate management of these difficult patients.

Postoperative respiratory insufficiency.

Respiratory insufficiency is one of the most common and most serious complications of the postoperative period. Preexisting risk factors include cardiopulmonary disease, significant smoking history, obesity and advanced age. The risk of postoperative respiratory insufficiency is increased in emergency surgical procedures (particularly those related to trauma), procedures involving the chest or upper abdomen and procedures requiring prolonged anesthesia. Postoperatively, prolonged sedation or neuromuscular blockade, cardiovascular instability, respiratory problems and immobilization are important risk factors. Common clinical causes of respiratory insufficiency are atelectasis, aspiration, pulmonary edema and pulmonary embolism. Management strategies are directed at treatment of the cause of the insufficiency and restoration of pulmonary function. All surgical patients should be carefully assessed before surgery, monitored closely during and after the procedure, and aggressively treated to prevent or correct respiratory insufficiency.

Correlation between measured energy expenditure and clinically obtained variables in trauma and sepsis patients.

BACKGROUND: Indirect calorimetry is the preferred method for determining caloric requirements of patients, but availability of the device is limited by high cost. A study was therefore conducted to determine whether clinically obtainable variables could be used to predict metabolic rate. METHODS: Patients with severe trauma or sepsis who required mechanical ventilation were measured by an open-circuit indirect calorimeter. Several clinical variables were obtained simultaneously. Measurements were repeated every 12 hours for up to 10 days. RESULTS: Twenty-six trauma and 30 sepsis patients were measured 423 times. Mean resting energy expenditure was 36 +/- 7 kcal/kg (trauma) vs 45 +/- 8 kcal/kg (sepsis) (p < .0001). The single strongest correlate with resting energy expenditure was minute ventilation (R2 = 0.61, p < .0001). Doses of dopamine, dobutamine, morphine, fentanyl, and neuromuscular blocking agents each correlated positively with resting energy expenditure. In the case of the inotropics and neuromuscular blockers, there was a probable covariance with severity of illness. A multiple regression equation was developed using minute ventilation, predicted basal energy expenditure, and the presence or absence of sepsis: resting energy expenditure = -11000 + minute ventilation (100) + basal energy expenditure (1.5) + dobutamine dose (40) + body temperature (250) + diagnosis of sepsis (300) (R2 = 0.77, p < .0001). CONCLUSION: Severe trauma and sepsis patients are hypermetabolic, but energy expenditure is predictable from clinical data. The regression equations probably apply only to severe trauma and sepsis. Other studies should be conducted to predict energy expenditure in other patient types.

Management of blunt vascular trauma to the extremities.

During a seven and one-half year period from 1984 to 1991, 106 patients admitted to a Level I trauma center had blunt vascular injury to the extremities. This subset of patients was analyzed with respect to mechanism of injury, associated injuries, method of repair, morbidity and mortality. Twenty patients sustained vascular injuries of the upper limb. Eighty percent of the patients (16 patients) underwent primary vascular repairs, 15 percent had primary amputations and 5 percent (one patient) were observed. Eighty-eight percent (14 of 16 repairs) of the vascular repairs demonstrated excellent neurologic function postoperatively. Eighty-six patients had arterial injuries of the lower extremity. Forty-eight percent (41 patients) of the injured legs were amputated, 41 percent (35 patients) underwent vascular repairs, 6 percent (five patients) underwent ligation of the primary vessel with no amputation and 24 percent (21 patients) underwent no surgical procedure. Sixty-two percent of the 37 patients (23 patients) with popliteal injuries required amputation and 57 percent (21 patients) underwent vascular repair. The overall mortality rate was 11 percent--zero percent for injuries to the upper limb and 14 percent for injuries to the lower limb.

Continuous arteriovenous hemofiltration with dialysis (CAVH-D): an alternative to hemodialysis in the mass casualty situation.

Renal failure is a common sequela of mass casualty, particularly when crush injury is involved. Traditional management of renal failure with hemodialysis equipment may be difficult or inaccessible due to lack of electricity and water supply or damage to existing equipment. Furthermore, a sudden new population of renal failure patients may overwhelm an existing dialysis program. The rapid mobilization of traditional hemodialysis equipment may be delayed due to limited supply, manufacturing delays, or inventory shortages. For these reasons, we propose the use of continuous arteriovenous hemofiltration with dialysis (CAVH-D) as an alternative renal support modality for the mass casualty situation.