Laszlo N. Kiraly

Transfusion of aged packed red blood cells results in decreased tissue oxygenation in critically injured trauma patients.

BACKGROUND Blood transfusion is a common event in the treatment of injured patients. The effect of red blood cell transfusion on tissue oxygenation is unclear. The transfusion of older blood has been shown to be detrimental in retrospective studies. This study aims to study the effect of the age of the blood transfused on the tissue oxygenation using near infrared spectroscopy. METHODS Thirty-two critically injured trauma patients for whom a blood transfusion had been ordered were recruited. Each patient had a transcutaneous probe placed on the thenar eminence. The probe was placed 1 hour before the transfusion and left in place until 4 hours after transfusion. Tissue oxygen saturation (Sto2) was recorded every 2 minutes. The Sto2 area under the curve (AUC) over time periods was calculated. A control group (n = 16), not transfused, was recruited. The transfusion group was divided into two groups by blood age. One group received blood less than 21 days old, (new blood, n = 15) and the other received blood 21 days old or greater (old blood, n = 17). The data were analyzed for significance with Kendalls W and Wilcoxons signed rank test (p < 0.05). RESULTS Baseline characteristics such were not significantly different between groups. The baseline AUC did not differ between groups. The old blood group demonstrated a significant decline in Sto2 comparing its baseline period to its transfusion period (p < 0.05). There was no similar decline in the control group or the new blood group. The posttransfusion period AUC for the old blood group was also lower versus baseline (p = 0.06). There was a moderate correlation between increasing age of blood and decrease in oxygenation (r = 0.5). CONCLUSIONS There was a decrease in peripheral tissue oxygenation in patients receiving older red blood cells. There was no oxygenation decrease in patients receiving blood less than 21 days. This indicates that factors in stored blood may influence the peripheral vasculature and oxygen delivery.

Nutrition Optimization Prior to Surgery

Optimization of metabolic state prior to major surgery leads to improved surgical outcomes. Nutrition screening protocols should be implemented in the preoperative evaluation, possibly as part of a bundle. Strategies to minimize hyperglycemia and insulin resistance by aggressive preoperative nutrition and carbohydrate loading may promote maintenance of a perioperative anabolic state, improving healing, reducing complications, and shortening the time to recovery of bowel function and hospital discharge. Short courses of preoperative immune-modulating formulas, using combinations of arginine, ω-3 fatty acids, and other nutrients, have been associated with improved surgical outcomes. These immune-modulating nutrients are key elements of metabolic pathways that promote attenuation of the metabolic response to stress and improve both wound healing and immune function. Patients with severe malnutrition and gastrointestinal dysfunction may benefit from preoperative parenteral nutrition. Continuation of feeding through the intraoperative period for severely stressed hypermetabolic patients undergoing nongastrointestinal surgery is another strategy to optimize metabolic state and reduce prolonged nutrition deficits. In this paper, we review the importance of preoperative nutrition and strategies for effective preoperative nutrition optimization.

The use of indirect calorimetry in the intensive care unit.

Purpose of reviewThis review evaluates whether improvements have occurred in the value of predictive equations for use in designing nutritional therapeutic regimens in the ICU. The report also seeks to determine whether emerging strategies for nutrition therapy in the ICU change the need for an accurate measurement of energy requirements by indirect calorimetry. Recent findingsPredictive equations remain problematic for use in the critically ill patient. Inaccuracy of predictive equations introduces error in the design of a nutritional therapy regimen. The epidemic of obesity renders the calculations of requirements by predictive equations increasingly inaccurate at extremes of BMI. Certain patient populations appear to be hypometabolic, contradicting the traditional notion that critical illness increases energy expenditure. More recent data indicates that determination of which patients benefit from nutritional therapy may be based both on assessment of nutrition risk and delivery of sufficient nutrition therapy. SummaryThe role of indirect calorimetry in the ICU should be expected to increase in the near future, as predictive equations may be too inaccurate to identify the appropriate goals of nutrition therapy.

Management of colonic injuries in the combat theater.

PURPOSE: Combat injuries are more often associated with blast, penetrating, and high-energy mechanisms than civilian trauma, generating controversy about the management of combat colonic injury. Despite implementation of mandatory colostomy in World War II, recent civilian data suggest that primary repair without diversion is safe and feasible. This study describes the modern management of battle-related colonic injuries and seeks to determine whether management strategy affects early complications. METHODS: Records from the combat theater (downrange) and tertiary referral center in Germany were retrospectively reviewed from 2005 to 2006. Patient characteristics, management strategy, treatment course, and early complications were recorded. Comparison groups by management strategy were as follows: primary repair, diversion, and damage control. RESULTS: A total of 133 (97% male) patients sustained colonic injuries from penetrating (71%), blunt (5%), and blast (23%) mechanisms. Average injury severity score was 21 and length of stay in the referral center was 7.1 days. Injury distribution was 21% ascending, 21% descending, 15% transverse, 27% sigmoid, and 25% rectum. Downrange complications for primary repair, initial ostomy, and damage control groups were 14%, 15%, and 30%, respectively. On discharge from the center, 62% of patients had undergone a diversion. The complication rate was 18% overall and was unrelated to management strategy (P = .16). Multivariate analysis did not identify independent predictors of complications. CONCLUSION: Early complications were similar by mechanism, anatomic location, severity of injury, and management strategy. More diversions were performed for rectosigmoid injury. Good surgical judgment allows for low morbidity and supports primary repair in selected cases. Damage control surgery is effective in a multinational theater of operations.

The Outcomes of Obese Patients in Critical Care

The severity and prevalence of obesity continue to rise throughout the world. A similar rise in the prevalence of obesity is seen in the population of patients admitted to the intensive care unit (ICU). In the ICU setting, nearly every aspect of care is made more difficult by obesity. This review highlights the challenges in the care of obese ICU patients. Multiple statistical reviews have suggested improved outcomes for obese ICU patients. This article critically evaluates published outcome studies and highlights potential confounders that may result in misleading results. Body mass index (BMI) has been traditionally used to stratify risk in obese populations. Other factors that may be more predictive of poor outcomes in obese populations are further discussed. Further research in these factors has the potential to guide therapy in high-risk critically ill obese populations.

Ketamine-based Total Intravenous Anesthesia Versus Isoflurane Anesthesia in a Swine Model of Hemorrhagic Shock

BACKGROUND Inhalational anesthetics can cause profound hemodynamic effects including decreases in systemic vascular resistance and cardiac inotropy. Although widely used in uncontrolled hemorrhagic shock (UHS), their consequences compared with other anesthetic regimens are not well-studied. Ketamine-based total intravenous anesthesia (TIVA) may produce less profound cardiovascular depression, and has been used during elective surgery but rarely during traumatic shock. The purpose of this study was to compare the effects of isoflurane (ISO) and TIVA regimens in a swine grade V liver injury model. We hypothesized that TIVA would result in less hypotension and dysfunctional inflammation than ISO. METHODS Twenty swine were randomized blindly to receive either 1% to 3% ISO, or intravenous ketamine, midazolam, and buprenorphine for maintenance anesthesia. Six animals acted as controls. After sedation and intubation, randomized anesthesia was initiated and monitored by an independent animal technician. Invasive lines were placed followed by celiotomy and splenectomy. Baseline mean arterial pressure (MAP) was documented and a grade V liver injury created. After 30 minutes of UHS, animals were resuscitated with 8 mL of Ringers lactate per milliliter blood loss at 165 mL/min. MAP and tissue oxygen saturation (StO2) were continuously recorded. The animals were sacrificed 120 minutes after injury and lung tissue was harvested. Serum cytokines (interleukin-6 [IL-6], IL-8, and tumor necrosis factor-alpha [TNF-alpha]) were quantified with enzyme-linked immunosorbent assay. Lung cytokine mRNA levels were quantified with real time reverse transcriptase polymerase chain reaction. RESULTS Animal weight, liver injury pattern, and blood loss were similar (p > 0.1). The ISO group had a lower MAP at baseline (p = 0.02), at injury (p = 0.004), and study completion (p = 0.001). After resuscitation, MAP decreased in the ISO group but remained stable in the TIVA group. StO2 was significantly higher in the TIVA group immediately after injury (p = 0.004), but similar between groups throughout the remainder of the study. Animals who received TIVA trended toward higher levels of lactate and lower pH throughout the study, reaching significance at 30 minutes postinjury (p = 0.037 and 0.043). Inflammatory cytokine (IL-6, IL-8, and TNF-alpha) production did not differ between groups, however TNF-alpha mRNA production was significantly lower in the TIVA group (p = 0.04). CONCLUSION Although a TIVA regimen produced less pronounced hypotension in a swine model of UHS than did ISO, end-organ perfusion with TIVA appeared to be equivalent or inferior to ISO. In circumstances of limited resources, such as those experienced by forward Army surgical teams, a ketamine-based TIVA regimen may be an option for use in UHS.

Cryopreserved red blood cells are superior to standard liquid red blood cells.

BACKGROUND Liquid preserved packed red blood cell (LPRBC) transfusions are used to treat anemia and increase end-organ perfusion. Throughout their storage duration, LPRBCs undergo biochemical and structural changes collectively known as the storage lesion. These changes adversely affect perfusion and oxygen off-loading. Cryopreserved RBCs (CPRBC) can be stored for up to 10 years and potentially minimize the associated storage lesion. We hypothesized that CPRBCs maintain a superior biochemical profile compared with LPRBCs. METHODS This was a prospective, randomized, double-blinded study. Adult trauma patients with an Injury Severity Score (ISS) greater than 4 and an anticipated 1-U to 2-U transfusion of PRBCs were eligible. Enrolled patients were randomized to receive either CPRBCs or LPRBCs. Serum proteins (haptoglobin, serum amyloid P, and C-reactive protein), proinflammatory and anti-inflammatory cytokines, d-dimer, nitric oxide, and 2,3-DPG concentrations were analyzed. Mann-Whitney U-test and Wilcoxon rank sum test were used to assess significance (p < 0.05). RESULTS Fifty-seven patients were enrolled (CPRBC, n = 22; LPRBC, n = 35). The LPRBC group’s final interleukin 8, tumor necrosis factor &agr;, and d-dimer concentrations were elevated compared with their pretransfusion values (p < 0.05). After the second transfused units, 2,3-DPG was higher in the patients receiving CPRBCs (p < 0.05); this difference persisted throughout the study. Finally, serum protein concentrations were decreased in the transfused CPRBC units compared with LPRBC (p < 0.01). CONCLUSION CPRBC transfusions have a superior biochemical profile: an absent inflammatory response, attenuated fibrinolytic state, and increased 2,3-DPG. A blood banking system using both storage techniques will offer the highest-quality products to critically injured patients virtually independent of periodic changes in donor availability and transfusion needs. LEVEL OF EVIDENCE Therapeutic study, level II.

Nutrition Delivery for Obese ICU Patients Delivery Issues, Lack of Guidelines, and Missed Opportunities

The most appropriate enteral formula for the severely obese population has yet to be determined. The obese patient in the intensive care unit (ICU) creates numerous difficulties for managing care, one being the ability to deliver appropriate and timely nutrition. Access for nutrition therapy, either enteral or parenteral, can also create a challenge. Currently, no specific guidelines are available on a national or international scale to address the issues of how and when to feed the obese patient in the ICU. A bias against feeding these patients exists, secondary to the perception that an enormous quantity of calories is stored in adipose tissue. Making a specialty enteral formula for obesity from existing commercial formulas and other modular nutrient components is not practical, secondary to difficulty with solubility issues, dilution of the formula, and safety concerns. Using todays concepts and current metabolic data, a formula could be produced that would address many of the specific metabolic derangements noted in obesity. This formula should have a high-protein, low-carbohydrate content with at least a portion of the lipid source coming from fish oil. Specific nutrients that may be beneficial in obesity include arginine, glutamine, leucine, L-carnitine, lipoic acid, S-adenosylmethionine, and betaine. Certain trace minerals such as magnesium, zinc, and selenium may also be of value in the obese population. The concept of a specific bariatric formulation for the ICU setting is theoretically sound, is scientifically based, and could be delivered to patients safely.

Cryopreserved deglycerolized blood is safe and achieves superior tissue oxygenation compared with refrigerated red blood cells: a prospective randomized pilot study.

BACKGROUND During preservation, donated liquid red blood cells (RBCs) experience multiple functional and structural changes known as the storage lesion. Increased RBC age is associated with increased infection rates, organ failure, and mortality. METHODS This prospective, randomized, double-blinded pilot study enrolled stable trauma patients who required RBC transfusion. Patients were randomly assigned to receive standard or cryopreserved RBCs. Continuous tissue oxygenation (StO2) monitoring was performed during the peritransfusion period. Hematocrit and thrombelastography before and after transfusion were evaluated. Patients were monitored for transfusion reactions and clinical outcomes. RESULTS Fifty-seven patients were randomized, and groups were well matched for demographics and Injury Severity Score (ISS). No statistically significant differences were noted in hematocrit change, thrombelastography parameters, transfusion reactions, or clinical outcomes. StO2 was found to be higher in the cryopreserved group. CONCLUSION Cryopreserved RBCs are equally safe and efficacious to refrigerated RBCs. This storage technique extends the life span of RBCs to 10 years, potentially preserving a precious resource and preventing the storage lesion. StO2 was superior in patients receiving cryopreserved RBCs. This finding has the potential to drive a paradigm shift in transfusion practices. LEVEL OF EVIDENCE Therapeutic study, level II.

Management of the crushed chest.

Thoracic injuries are very common among trauma victims. This article reviews the current literature on the management of multiple aspects of the care of the patient with severe chest injury. The mechanics of chest injury are complex and varied. Chest wall injuries are the most common and noticeable manifestation of thoracic trauma. Overall morbidity and mortality are primarily determined by associated injuries. New ventilatory strategies permit oxygenation of the severely hypoxic patient. Acute pain management modalities offer the potential of decreasing associated pulmonary complications. Surgical chest wall fixation is clearly indicated in extreme cases of pulmonary herniation and chest wall disruption. There are potential benefits of surgical fixation in other settings, although further trials are needed.