Relationship between injury severity and lactate levels in severely injured patients

Etiology and therapeutic approach to elevated lactate levels

Lactate levels are commonly evaluated in acutely ill patients. Although most often used in the context of evaluating shock, lactate levels can be elevated for many reasons. While tissue hypoperfusion may be the most common cause of elevation, many other etiologies or contributing factors exist. Clinicians need to be aware of the many potential causes of lactate level elevation as the clinical and prognostic importance of an elevated lactate level varies widely by disease state. Moreover, specific therapy may need to be tailored to the underlying cause of elevation. The present review is based on a comprehensive PubMed search between the dates of January 1, 1960, to April 30, 2013, using the search term lactate or lactic acidosis combined with known associations, such as shock, sepsis, cardiac arrest, trauma, seizure, ischemia, diabetic ketoacidosis, thiamine, malignancy, liver, toxins, overdose, and medication. We provide an overview of the pathogenesis of lactate level elevation followed by an in-depth look at the varied etiologies, including medication-related causes. The strengths and weaknesses of lactate as a diagnostic/prognostic tool and its potential use as a clinical end point of resuscitation are discussed. The review ends with some general recommendations on the management of patients with elevated lactate levels.

Prognostic value of shock index in children with septic shock

OBJECTIVES

Septic shock is frequent in children and is associated with high mortality and morbidity rates. Early recognition of severe sepsis improve outcome. Shock index (SI), ratio of heart rate (HR) and systolic blood pressure (SBP), may be a good noninvasive measure of hemodynamic instability that has been poorly studied in children. The aim of the study was to explore the usefulness of SI as an early index of prognosis for septic shock in children.

METHODS

The study was retrospective and performed in 1 pediatric intensive care unit at a university hospital. The following specific data were collected at 0, 1, 2, 4, and 6 hours after admission: HR and SBP for SI calculation and lactate concentration. Patients were divided into 2 groups according to their outcome (death/survival).

RESULTS

A total of 146 children admitted with septic shock between January 2000 and April 2010 were included. Shock index was significantly different between survivors and nonsurvivors at 0, 4, and 6 hours after admission (P = 0.02, P = 0.03, and P = 0.008, respectively). Age-adjusted SIs were different between survivors and nonsurvivors at 0 and 6 hours, with a relative risk of death at these time points of 1.85 (1.04-3.26) (P = 0.03) and 2.17 (1.18-3.96) (P = 0.01), respectively. Moreover, an abnormal SI both at admission and at 6 hours was predictive of death with relative risk of 1.36 (1.05-1.76).

CONCLUSIONS

In our population of children with septic shock, SI was a clinically relevant and easily calculated predictor of mortality. It could be a better measure of hemodynamic status than HR and SBP alone, allowing for the early recognition of severe sepsis.

Even mild hyperlactatemia is associated with increased mortality in critically ill patients

Introduction

The clinical significance of elevation of lactate levels within the reference range is not well studied. The objective of this study was to determine the best cutoff threshold for serum lactate within the reference range (0.01 to 2.00 mM) that best discriminated between survivors and nonsurvivors of critical illness and to examine the association between relative hyperlactatemia (lactate above the identified threshold) and mortality.

Methods

This was a retrospective cohort study of adult patients admitted to the medical-surgical intensive care unit (ICU) of a tertiary care academic center. Youden index was calculated to identify the best lactate cutoff threshold that discriminated between survivors and nonsurvivors. Patients with lactate above the identified threshold were defined as having relative hyperlactatemia. Multivariate logistic regression, adjusting for baseline variables, was performed to determine the relationship between the above two ranges of lactate levels and mortality. In addition, a test of interaction was performed to assess the effect of selected subgroups on the association between relative hyperlactatemia and hospital mortality.

Results

During the study period, 2,157 patients were included in the study with mean lactate of 1.3 ± 0.4 mM, age of 55.1 ± 20.3 years, and acute physiology and chronic health evaluation (APACHE) II score of 22.1 ± 8.2. Vasopressors were required in 42.4%. Lactate of 1.35 mM was found to be the best cutoff threshold for the whole cohort. Relative hyperlactatemia was associated with increased hospital mortality (adjusted odds ratio (aOR), 1.60, 95% confidence interval (CI) 1.29 to 1.98), and ICU mortality (aOR, 1.66; 95% CI, 1.26 to 2.17) compared with a lactate level of 0.01 to 1.35 mM. This association was consistent among all examined subgroups.

Conclusions

Relative hyperlactatemia (lactate of 1.36 to 2.00 mM) within the first 24 hours of ICU admission is an independent predictor of hospital and ICU mortality in critically ill patients.

Association between a geriatric trauma resuscitation protocol using venous lactate measurements and early trauma surgeon involvement and mortality risk

OBJECTIVES

To investigate whether implementing a geriatric resuscitation protocol that uses lactate-guided therapy with early trauma surgeon involvement is associated with lower mortality through the early recognition of occult hypoperfusion (OH).

DESIGN

Prospective cohort study.

SETTING

Level I trauma center.

PARTICIPANTS

All hemodynamically stable individuals with blunt trauma aged 65 and older admitted to the Level I trauma center from October 1, 2008, through December 31, 2011 (n = 1,998).

MEASUREMENTS

Mortality over time (according to quarter) was analyzed using an adjusted logarithmic regression model stratified according to the presence of OH. OH was defined as lactate of 2.5 mM or greater.

RESULTS

Overall mortality was 3.9% (n = 78). Admission venous lactate was collected in 73.5% of participants, of whom 20.5% had OH (n = 301). In participants with OH, a significant decrease in mortality was observed over time (adjusted coefficient of determination (R(2) ) = 0.66, P = .002). A smaller yet significant decrease in mortality rates in participants with normal perfusion status was also observed (adjusted R(2) = 0.55, P = .01).

CONCLUSION

Early identification and treatment of OH in elderly adults with trauma using venous lactate-guided therapy coupled with early trauma surgeon involvement was associated with significantly lower mortality. A protocol that uses lactate-guided therapy with early trauma surgeon involvement should be followed to improve the care of elderly adults with trauma.

Initial assessment of the role of CXC chemokine receptor 4 after polytrauma

CXC chemokine receptor (CXCR)-4 agonists have been shown to attenuate inflammation and organ injury in various disease models, including trauma/hemorrhage. The pathophysiological role of CXCR4 during the early response to tissue injury, however, remains unknown. Therefore, we investigated the effects of AMD3100, a drug that antagonizes binding of stromal cell-derived factor (SDF)-1α and ubiquitin to CXCR4 during the initial response to polytrauma in pigs. Fifteen minutes before polytrauma (femur fractures/lung contusion; control: sham), 350 nmol/kg AMD3100, equimolar AMD3100 and ubiquitin (350 nmol/kg each) or vehicle were administered intravenously. After a 60-min shock period, fluid resuscitation was performed for 360 min. Ubiquitin binding to peripheral blood mononuclear cells was significantly reduced after intravenous AMD3100. SDF-1α plasma levels increased transiently >10-fold with AMD3100 in all animals. In injured animals, AMD3100 increased fluid requirements to maintain hemodynamics and enhanced increases in peripheral blood granulocytes, lymphocytes and monocytes, compared with its effects in uninjured animals. Cytokine release from leukocytes in response to Toll-like receptor (TLR)-2 and TLR-4 activation was increased after in vitro AMD3100 treatment of normal whole blood and after in vivo AMD3100 administration in animals subjected to polytrauma. Coadministration of AMD3100/ubiquitin reduced lactate levels, prevented AMD3100-induced increases in fluid requirements and sensitization of the tumor necrosis factor (TNF)-α and interleukin (IL)-6 release upon TLR-2/4 activation, but did not attenuate increases in leukocyte counts and SDF-1α plasma levels. Our findings suggest that CXCR4 controls leukocyte mobilization after trauma, regulates leukocyte reactivity toward inflammatory stimuli and mediates protective effects during the early phase of trauma-induced inflammation.

Admission base deficit and lactate levels in Canadian patients with blunt trauma: are they useful markers of mortality?

BACKGROUND

Elevated base deficit (BD) and lactate levels at admission in patients with injury have been shown to be associated with increased mortality. This relationship is undefined in the Canadian experience. The goal of this study was to define the association between arterial blood gas (ABG) values at admission and mortality for Canadians with severe blunt injury.

METHODS

A retrospective review of 3,000 consecutive adult major trauma admissions (Injury Severity Score, ≥ 12) to a Canadian academic tertiary care referral center was performed. ABG values at the time of arrival were analyzed with respect to associated mortality and length of stay.

RESULTS

A total of 2,269 patients (76%) had complete data available for analysis. After exclusion of patients who sustained a penetrating injury or were admitted for minor falls (ground levels or low height), 445 had an ABG drawn within 2 hours of arrival. Patients who died displayed a higher median lactate (3.6 vs. 2.2, p < 0.0001), a worse median BD (-10 vs. -5, p < 0.0001), and a lower pH (7.23 vs. 7.31, p < 0.0001) at arrival compared with those of survivors. A statistically significant association was also observed between lactate and BD values at arrival and both mortality and length of stay (p < 0.0001).

CONCLUSION

Despite population differences, ABGs at admission in Canadian patients with blunt trauma accurately reflect mortality in a similar manner to the previously published literature. Survival curves with lactate and BD values at arrival should be available to all clinicians within their individual trauma centers for both acute care and quality assurance.

LEVEL OF EVIDENCE

Prognostic study, level III.

Damage control in severely injured trauma patients - A ten-year experience

BACKGROUND

This study reviews our 10-year institutional experience with damage control management and investigates risk factors for early mortality.

MATERIALS AND METHODS

The trauma registry of our level I trauma centre was utilized to identify all patients from 01/96 through 12/05 who underwent initial damage control procedures. Demographics, clinical and physiological parameters, and outcomes were abstracted. Patients were categorized as either early survivors (surviving the first 72 hours after admission) or early deaths.

RESULTS

During the study period, 319 patients underwent damage control management. Overall, 52 patients (16.3%) died (early deaths) and 267 patients (83.7%) survived the first 72 hours (early survivors). Early deaths showed significantly deranged serum lactate (5.81±0.55 vs. 3.46±0.13 mmol/L; P<0.001), base deficit (10.10±0.95 vs. 4.90±0.28 mmol/L; P<0.001) and pH (7.16±0.03 vs. 7.29±0.01; P<0.001) levels compared to early survivors on hospital admission. An International Normalized Ratio >1.2, base deficit >3 mmol/L, head Abbreviated Injury Scale ≥3, body temperature <35°C, serum lactate >6 mmol/L, and hemoglobin <7 g/dL proved to be independent risk factors for early mortality on hospital admission.

CONCLUSIONS

Several risk factors for early mortality such as severe head injury and the lethal triad (coagulopathy, acidosis and hypothermia) in patients undergoing damage control procedures were identified and should trigger the trauma surgeon to maintain aggressive resuscitation in the intensive care unit.

Use of serial measurements of peritoneal fluid lactate concentration to identify strangulating intestinal lesions in referred horses with signs of colic

OBJECTIVE

To determine the value of serial measurements of peritoneal fluid lactate concentration (PFL) for detecting strangulating intestinal lesions (SLs) in referred horses with signs of colic.

DESIGN

Retrospective cohort study.

ANIMALS

94 horses with signs of colic.

PROCEDURES

Medical records of horses evaluated between September 2006 and February 2010 because of signs of colic were reviewed. All included horses had ≥ 2 peritoneal fluid samples collected, including one at admission and another within 1 to 6 hours after admission. Of the 94 horses, 26 were assigned to the SL group on the basis of findings at surgery or necropsy and 68 were assigned to the nonstrangulating intestinal lesion group because their signs of colic resolved with medical management. Peritoneal fluid lactate concentration was measured by use of a handheld lactate monitor. Data were analyzed by use of univariable and multivariable logistic regression analysis.

RESULTS

PFL at admission > 4 mmol/L, an increase in PFL over time, and especially an increase in PFL over time in horses with a PFL < 4 mmol/L at admission (OR, 62; sensitivity, 95%; specificity, 77%) were significant predictors of horses with an SL.

CONCLUSIONS AND CLINICAL RELEVANCE

Serially determined PFL was a strong predictor for differentiating horses with SLs from horses with nonstrangulating intestinal lesions. Given the high OR, sensitivity, and specificity of these tests, serially determined PFL may have potential as a screening test for identifying horses with SLs. Further evaluation of the clinical value of PFL for predicting SLs in a prospective, multicenter study is warranted.

Lactate clearance in cardiogenic shock following ST elevation myocardial infarction: a pilot study

BACKGROUND

Recent studies documented that serial lactate measurements over time may be clinically more reliable than lactate absolute value for risk stratification. The aim of the present investigation was to assess the role of lactate clearance in predicting early death in cardiogenic shock (CS) following ST-elevation myocardial infarction (STEMI) submitted to primary percutaneous coronary intervention (PCI).

METHODS

51 consecutive patients with CS following STEMI were prospectively enrolled. Lactate was measured in Intensive Cardiac Care Unit (ICCU) on admission and on the twelfth hour. Logistic regression analysis was performed to identify the independent predictors for in-ICCU mortality. Receiver operating characteristic (ROC) curve was constructed in order to identify cut-off for admission lactate and for 12-h lactate clearance in relation to in-ICCU mortality. Follow-up survival rate were investigated by Kaplan-Meier curves.

RESULTS

At 12 h from admission, lactate clearance was higher in survivors (P=0.013). A higher in-ICCU mortality was observed in patients with 12 hours lactate clearance<10% (P=0.002). At follow up, patients with 12-h lactate clearance<10% showed a significantly lower survival rate.

CONCLUSIONS

In patients with CS following STEMI, 12-h lactate clearance<10% identifies a subset of patients at higher risk for death at short and long-term.

Systemic release of cytokines and heat shock proteins in porcine models of polytrauma and hemorrhage*

OBJECTIVE

To define systemic release kinetics of a panel of cytokines and heat shock proteins in porcine polytrauma/hemorrhage models and to evaluate whether they could be useful as early trauma biomarkers.

DESIGN

Prospective observational study.

SETTING

Research laboratory.

SUBJECTS

Twenty-one Yorkshire pigs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Pigs underwent polytrauma (femur fractures/lung contusion, P), hemorrhage (mean arterial pressure 25-30 mm Hg, H), polytrauma plus hemorrhage (P/H), or sham procedure (S). Plasma was obtained at baseline, in 5- to 15-min intervals during a 60-min shock period without intervention, and in 60- to 120-min intervals during fluid resuscitation for up to 300 min. Plasma was assayed for interleukin-1β, interleukin-4, interleukin-5, interleukin-6, interleukin-8, interleukin-10, interleukin-12/interleukin-23p40, interleukin-13, interleukin-17, interleukin-18, interferonγ, transforming growth factor-β, tumor necrosis factor-α, heat shock protein 40, heat shock protein 70, and heat shock protein 90 by enzyme-linked immunosorbent assay. All animals after S, P, and H survived (n = 5/group). Three of six animals after P/H died. Interleukin-10 increased during shock after P and this increase was attenuated after H. Tumor necrosis factor-α increased during the shock period after P, H, and also after S. P/H abolished the systemic interleukin-10 and tumor necrosis factor-α release and resulted in 20% to 30% increased levels of interleukin-6 during shock. As fluid resuscitation was initiated, tumor necrosis factor-α and interleukin-10 levels decreased after P, H, and P/H; heat shock protein 70 increased after P; and interleukin-6 levels remained elevated after P/H and also increased after P and S.

CONCLUSIONS

Differential regulation of the systemic cytokine release after polytrauma and/or hemorrhage, in combination with the effects of resuscitation, can explain the variability and inconsistent association of systemic cytokine/heat shock protein levels with clinical variables in trauma patients. Insults of major severity (P/H) partially suppress the systemic inflammatory response. The plasma concentrations of the measured cytokines/heat shock proteins do not reflect injury severity or physiological changes in porcine trauma models and are unlikely to be able to serve as useful trauma biomarkers in patients.

Blood lactate as a predictor for in-hospital mortality in patients admitted acutely to hospital: a systematic review

BACKGROUND

Using blood lactate monitoring for risk assessment in the critically ill patient remains controversial. Some of the discrepancy is due to uncertainty regarding the appropriate reference interval, and whether to perform a single lactate measurement as a screening method at admission to the hospital, or serial lactate measurements. Furthermore there is no consensus whether the sample should be drawn from arterial, peripheral venous, or capillary blood. The aim of this review was: 1) To examine whether blood lactate levels are predictive for in-hospital mortality in patients in the acute setting, i.e. patients assessed pre-hospitally, in the trauma centre, emergency department, or intensive care unit. 2) To examine the agreement between arterial, peripheral venous, and capillary blood lactate levels in patients in the acute setting.

METHODS

We performed a systematic search using PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and CINAHL up to April 2011. 66 articles were considered potentially relevant and evaluated in full text, of these ultimately 33 articles were selected.

RESULTS AND CONCLUSION

The literature reviewed supported blood lactate monitoring as being useful for risk assessment in patients admitted acutely to hospital, and especially the trend, achieved by serial lactate sampling, is valuable in predicting in-hospital mortality. All patients with a lactate at admission above 2.5 mM should be closely monitored for signs of deterioration, but patients with even lower lactate levels should be considered for serial lactate monitoring. The correlation between lactate levels in arterial and venous blood was found to be acceptable, and venous sampling should therefore be encouraged, as the risk and inconvenience for this procedure is minimal for the patient. The relevance of lactate guided therapy has to be supported by more studies.

Prehospital serum lactate as a predictor of outcomes in trauma patients: a retrospective observational study

BACKGROUND

Lactate is associated with morbidity and mortality; however, the value of prehospital lactate (pLA) is unknown. Our objective was to determine whether pLA improves identification of mortality and morbidity independent of vital signs.

METHODS

We measured pLA in 1,168 patients transported by rotorcraft to a Level I trauma center over 18 months. The primary outcome was in-hospital mortality; secondary outcomes were emergent surgery and multiple organ dysfunction syndrome (MODS). Covariates include age, sex, prehospital vital signs, and mental status. We created multivariable logistic regression models and tested them for interaction terms and goodness of fit. Cutoff values were established for reporting operating characteristics using shock (defined as shock index >0.8, heart rate >110, and systolic blood pressure <100), tachypnea (RR ≥30), and altered sensorium (Glasgow Coma Scale score <15).

RESULTS

In-hospital mortality was 5.6%, 7.4% required surgery and 5.7% developed MODS. Median lactate was 2.4 mmol/L. Lactate was associated with mortality (odds ratio [OR], 1.23; p < 0.0001), surgery (OR, 1.13; p < 0.001), and MODS (OR, 1.14; p < 0.0001). Inclusion of pLA into a logistic model significantly improved the area under the receiver operator curves from 0.85 to 0.89 for death (p < 0.001), 0.68 to 0.71 for surgery (p = 0.02), and 0.78 to 0.81 for MODS (p = 0.002). When a threshold lactate value of >2 mmol/L was added to a predictive model of shock, respiratory distress, or altered sensorium, it improved sensitivity from 88% to 97% for death, 64% to 86% for surgery, and 94% to 99% for MODS.

CONCLUSION

The pLA measurements improve prediction of mortality, surgery, and MODS. Lactate may improve the identification of patients who require monitoring, resources, and resuscitation.

Lactate in the acute phase of ST-elevation myocardial infarction treated with mechanical revascularization: a single-center experience

AIMS

The prognostic role (if any) of lactate for early mortality in patients with ST-elevation myocardial infarction (STEMI) submitted to primary percutaneous coronary intervention (PCI) is so far not elucidated. We therefore assessed whether lactic acid (LA) was a prognostic predictor for early mortality in 807 patients with STEMI submitted to primary PCI consecutively admitted to our intensive cardiac care unit (ICCU) from January 1, 2006, to December 31, 2009.

RESULT

Higher levels of LA were found in older patients (P = .025) and were associated with a progressive decline in estimated glomerular filtration rate (P < .001) and in ejection fraction (P < .001). The increase in LA values paralleled the progressive increase in glucose values, peak glycemia, troponin I, N-terminal pro-brain natriuretic peptide, and uric acid (P < .001, P < .001, P < .001, P = .018, and P = .006, respectively). The in-ICCU mortality rate was highest in the third LA tertile (P < .001). Lactate levels were independent predictors for in-hospital mortality only in patients with Killip classes III to IV (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.05-1.30, P = .003). In addition, age (OR, 1.11; 95% CI, 1.03-1.19, P = .006) and leukocytes (OR, 1.17; 95% CI, 1.03-1.33, P = .015) were independent predictors for in-hospital mortality when adjusted for PCI failure.

CONCLUSION

In patients with STEMI submitted to primary PCI, blood lactate is a prognostic marker for early mortality only in the subgroup with advanced Killip class. The degree of hemodynamic impairment (as indicated by Killip class), of myocardial ischemia (as inferred by troponin I), and glucose values are the main factors influencing lactate concentrations in the early phase of STEMI.

The role of serum lactate in the acute care setting

Acute care services are increasingly faced with the double burden of high patient acuity and limited resources. Early identification of patients who are sick or who have the potential to deteriorate rapidly is crucial so that these resources may be allocated to those in greatest need. Traditional measures of illness and end points of resuscitation, such as vital signs, often fail to identify occult hypoperfusion with certain disease processes associated with high morbidity and mortality. Thus, biochemical markers that may predict illness earlier are becoming more relevant. We present a review of the evidence behind use of the serum lactate level in this setting.

Sequential plasma lactate concentrations as prognostic indicators in adult equine emergencies

BACKGROUND

Sequential lactate concentration ([LAC]) measurements have prognostic value in that hospitalized humans and neonatal foals that have a delayed return to normolactatemia have greater morbidity and case fatality rate.

HYPOTHESIS

Prognosis for survival is decreased in horses with a delayed return to normal [LAC].

ANIMALS

Two hundred and fifty adult horses presented for emergency evaluation excepting horses evaluated because of only ophthalmologic conditions, superficial wounds, and septic synovitis without systemic involvement.

METHODS

Prospective observational study. [LAC] was measured at admission and then at 6, 12, 24, 48, and 72 hours after admission. The change in [LAC] over time ([LAC]deltaT) was calculated from changes in [LAC] between sampling points.

RESULTS

Median [LAC] was significantly (P < .001) higher at admission in nonsurvivors (4.10 mmol/L [range, 0.60-18.20 mmol/L]) when compared with survivors (1.30 mmol/L [range, 0.30-13.90 mmol/L]) and this difference remained at all subsequent time points. The odds ratio for nonsurvival increased from 1.29 (95% confidence interval 1.17-1.43) at admission to 49.90 (6.47-384) at 72 hours after admission for every 1 mmol/L increase in [LAC]. [LAC]deltaT was initially positive in all horses but became negative and significantly lower in nonsurvivors for the time periods between 24-72 hours (- 0.47, P = .001) and 48-72 hours (- 0.07, P = .032) when compared with survivors (0.00 at both time periods) consistent with lactate accumulation in nonsurvivors.

CONCLUSIONS AND CLINICAL IMPORTANCE

These results indicate that lactate metabolism is impaired in critically ill horses and [LAC]deltaT can be a useful prognostic indicator in horses.

Intestinal-FABP and liver-FABP: Novel markers for severe abdominal injury

OBJECTIVES

Fatty acid-binding proteins (FABPs) have relatively high tissue concentrations and low plasma concentrations and are released into the circulation following organ injury. We explored the utility of intestinal-(I)-FABP and liver-(L)-FABP for the diagnosis of abdominal injury in patients with multiple trauma.

METHODS

This prospective study included 102 trauma patients and 30 healthy volunteers. Plasma I-FABP and L-FABP levels were measured in the emergency department (ED) by enzyme-linked immunosorbent assay (ELISA). Forty-one patients suffered from serious or severe abdominal trauma (Abbreviated Injury Score [AIS] code "ai" for abdominal injury, AISai > or = 3) and nine were moderately abdominally injured (AISai < 3). Fifty-two had no abdominal injury.

RESULTS

Median I-FABP and L-FABP levels in the AISai > or = 3 group (516 pg/mL and 135 ng/mL, respectively) were significantly higher compared to the AISai < 3 group (154 pg/mL and 13 ng/mL, respectively) or those without abdominal injury (207 pg/mL and 21 ng/mL, respectively) or normal controls (108 pg/mL and 13 ng/mL, respectively). The cutoff to distinguish the ai > or = 3 is 359 pg/mL for I-FABP and 54 ng/mL for L-FABP, with 93% specificity and 75% sensitivity for I-FABP and 93% and 82% for L-FABP, respectively.

CONCLUSIONS

High I-FABP and L-FABP levels correlate with relevant severity of abdominal tissue damage in patients with multiple trauma. I-FABP and L-FABP could be useful as markers for the early detection of significant abdominal injury in acute multiple trauma and identify patients who require rapid intervention.

Diaspirin cross-linked hemoglobin infusion did not influence base deficit and lactic acid levels in two clinical trials of traumatic hemorrhagic shock patient resuscitation

BACKGROUND

Diaspirin cross-linked hemoglobin (DCLHb) has demonstrated a pressor effect that could adversely affect traumatic hemorrhagic shock patients through diminished perfusion to vital organs, causing base deficit (BD) and lactate abnormalities.

METHODS

Data from two parallel, multicenter traumatic hemorrhagic shock clinical trials from 17 US Emergency Departments and 27 European Union prehospital services using DCLHb, a hemoglobin-based resuscitation fluid.

RESULTS

In the 219 patients, the mean age was 37.3 years, 64% of the patients sustained a blunt injury, 48% received DCLHb resuscitation, and the overall 28-day mortality rate was 36.5%. BD data did not differ by treatment group (DCLHb vs. normal saline [NS]) at any time point. Study entry BD was higher in patients who died when compared with survivors in both studies (US: -14.7 vs. -9.3 and European Union: -11.1 vs. -4.1 mEq/L, p < 0.003) and at the first three time points after resuscitation. No differences in BD based on treatment group were observed in either those who survived or those who died from the hemorrhagic shock. US lactate data did not differ by treatment group (DCLHb vs. NS) at any time point. Study entry lactates were higher in US patients who ultimately died when compared with survivors (82.4 vs. 56.1 mmol/L, p < 0.003) and at all five postresuscitation time points. No lactate differences were observed between DCLHb and NS survivors or in those who died based on treatment group.

CONCLUSIONS

Although patients who died had more greatly altered perfusion than those who survived, DCLHb treatment of traumatic hemorrhagic shock patients was not associated with BD or lactate abnormalities that would indicate poor perfusion.

Hypotensive resuscitation

Hypotensive resuscitation in the trauma setting can be defined as deliberately allowing blood pressure to remain below normal until any active bleeding has been controlled. The dangers of aggressive fluid resuscitation in trauma were recognised as long ago as the First World War, in the intervening time, aggressive fluid resuscitation has become a mainstay of trauma management. More recently this trend of aggressive fluid resuscitation for trauma management seems to be reversing. Aggressive fluid resuscitation in trauma is based on animal studies from the 1950s and 1960s. These studies used models of controlled haemorrhage rather than uncontrolled haemorrhage. More recent studies using models of uncontrolled haemorrhage suggest an improved outcome with hypotensive resuscitation. Should there be a potential for uncontrolled haemorrhage a permissive hypotensive resuscitation strategy should be pursued until the haemorrhage has been controlled, but in certain types of trauma including blunt trauma and brain trauma the data is unclear as to the best fluid resuscitation strategy.

The role of pre-hospital blood gas analysis in trauma resuscitation

Background

To assess, whether arterial blood gas measurements during trauma patient's pre-hospital shock resuscitation yield useful information on haemodynamic response to fluid resuscitation by comparing haemodynamic and blood gas variables in patients undergoing two different fluid resuscitation regimens.

Methods

In a prospective randomised study of 37 trauma patients at risk for severe hypovolaemia, arterial blood gas values were analyzed at the accident site and on admission to hospital. Patients were randomised to receive either conventional fluid therapy or 300 ml of hypertonic saline. The groups were compared for demographic, injury severity, physiological and outcome variables.

Results

37 patients were included. Mean (SD) Revised Trauma Score (RTS) was 7.3427 (0.98) and Injury Severity Score (ISS) 15.1 (11.7). Seventeen (46%) patients received hypertonic fluid resuscitation and 20 (54%) received conventional fluid therapy, with no significant differences between the groups concerning demographic data or outcome. Base excess (BE) values decreased significantly more within the hypertonic saline (HS) group compared to the conventional fluid therapy group (mean BE difference -2.1 mmol/l vs. -0.5 mmol/l, p = 0.003). The pH values on admission were significantly lower within the HS group (mean 7.31 vs. 7.40, p = 0.000). Haemoglobin levels were in both groups lower on admission compared with accident site. Lactate levels on admission did not differ significantly between the groups.

Conclusion

Pre-hospital use of small-volume resuscitation led to significantly greater decrease of BE and pH values. A portable blood gas analyzer was found to be a useful tool in pre-hospital monitoring for trauma resuscitation.

Relative hyperlactatemia and hospital mortality in critically ill patients: a retrospective multi-centre study

Introduction

Higher lactate concentrations within the normal reference range (relative hyperlactatemia) are not considered clinically significant. We tested the hypothesis that relative hyperlactatemia is independently associated with an increased risk of hospital death.

Methods

This observational study examined a prospectively obtained intensive care database of 7,155 consecutive critically ill patients admitted to the Intensive Care Units (ICUs) of four Australian university hospitals. We assessed the relationship between ICU admission lactate, maximal lactate and time-weighted lactate levels and hospital outcome in all patients and also in those patients whose lactate concentrations (admission n = 3,964, maximal n = 2,511, and time-weighted n = 4,584) were under 2 mmol.L^-1 (i.e. relative hyperlactatemia).

Results

We obtained 172,723 lactate measurements. Higher admission and time-weightedlactate concentration within the reference range was independently associated with increased hospital mortality (admission odds ratio (OR) 2.1, 95% confidence interval (CI) 1.3 to 3.5, P = 0.01; time-weighted OR 3.7, 95% CI 1.9 to 7.00, P < 0.0001). This significant association was first detectable at lactate concentrations > 0.75 mmol.L^-1. Furthermore, in patients whose lactate ever exceeded 2 mmol.L^-1, higher time-weighted lactate remained strongly associated with higher hospital mortality (OR 4.8, 95% CI 1.8 to 12.4, P < 0.001).

Conclusions

In critically ill patients, relative hyperlactataemia is independently associated with increased hospital mortality. Blood lactate concentrations > 0.75 mmol.L^-1 can be used by clinicians to identify patients at higher risk of death. The current reference range for lactate in the critically ill may need to be re-assessed.

Occurrence and adverse effect on outcome of hyperlactatemia in the critically ill

INTRODUCTION

Hyperlactatemia is frequent in critically ill patients and is often used as a marker of adverse outcome. However, studies to date have focused on selected intensive care unit (ICU) populations. We sought to determine the occurrence and relation of hyperlactatemia with ICU mortality in all patients admitted to four ICUs in a large regional critical care system.

METHODS

All adults ([greater than or equal to] 18 years) admitted to ICUs in the Calgary Health Region (population 1.2 million) during 2003 to 2006 were included retrospectively. Lactate determinations were at the discretion of the attending service and hyperlactatemia was defined by a lactate level > 2 mmol/L.

RESULTS

A total of 13,932 ICU admissions occurred among 11,581 patients. The median age was 63 years (37% female), the mean APACHE II score was 25 +/- 9 (n = 13,922). At presentation (within first day of admission), 12,246 patients had at least one lactate determination and the median peak lactate was 1.8 (IQR 1.2 to 2.9) mmol/L. The cumulative incidence of at least one documented episode of hyperlactatemia was 5578/13,932 (40%); 5058 (36%) patients had hyperlactatemia at presentation, and a further 520 (4%) developed hyperlactatemia subsequently. The incidence of hyperlactatemia varied significantly by major admitting diagnostic category (P < 0.001) and was highest among neuro/trauma patients 1053/2328 (45%), followed by medical 2047/4935 (41%), other surgical 900/2274 (40%), and cardiac surgical 1578/4395 (36%). Among a cohort of 9107 first admissions with ICU stay of at least one day, both hyperlactatemia at presentation (712/3634 (20%) vs. 289/5473 (5%); P < 0.001) and its later development (101/379 (27%) vs. 188/5094 (4%); P < 0.001) were associated with significantly increased case fatality rates as compared with patients without elevated lactate. After controlling for confounding effects in multivariable logistic regression analysis, hyperlactatemia was an independent risk factor for death.

CONCLUSIONS

Hyperlactatemia is common among the critically ill and predicts risk for death.

Serum lactate and base deficit as predictors of mortality in normotensive elderly blunt trauma patients

BACKGROUND

Base deficit (BD) and lactate are used as markers of mortality, injury severity, and resource utilization in the general trauma population. No study has defined the role of these markers in the triage and management of the normotensive injured elderly patient.

METHODS

Retrospective cohort study of the trauma registry from a Level I trauma Center during the period of January 1, 2000 through December 31, 2006. Inclusion criteria were age > or = 65 years, initial systolic blood pressure > or = 90 mm Hg; blunt mechanism of trauma. Lactate was categorized as 0 to 2.4 mmol/L (normal), 2.5 to 4.0 mmol/L (moderately elevated), or > 4.0 mmol/L (severely elevated). BD was categorized as > 0 mEq/L (normal), 0 to -6 mEq/L (moderate), or < -6 mEq/L (severe). The primary outcome was inhospital mortality.

RESULTS

Mean lactate was higher in nonsurvivors compared with survivors (2.8 mm/L +/- 1.8 mm/L vs. 2.0 mm/L +/- 1.0 mm/L, p < 0.001). Normal, moderately elevated, and severely elevated lactate was associated with mortality rates of 15% (95% confidence interval [CI] 12-18.8%), 23.4% (95% CI 2-32.4%), and 39.6% (95% CI 26.5-52.8%), respectively. Compared with the normal lactate group, patients in the severely elevated lactate group had 4.2 increased odds of death. BD was more abnormal in nonsurvivors compared with survivors (-2.3 mEq/L +/- 5.2 mEq/L vs. 0.28 mEq/L +/- 1.0 mEq/L, p < 0.001). Normal, moderate, and severe BD were associated with mortality rates of 14% (95% CI 10.3-17.1%), 27% (95% CI 20.1-34.2%), and 40% (95% CI 24.9-54.1%), respectively. Compared with the normal BD group, patients in the severe group had 4.1 increased odds of death.

CONCLUSIONS

Both lactate and BD were associated with significantly increased mortality in normotensive elderly blunt trauma patients. However, because of the high baseline mortality rates in elderly trauma patients, "normal" lactate does not offer complete reassurance to the clinician.

Venous glucose and arterial lactate as biochemical predictors of mortality in clinically severely injured trauma patients--a comparison with ISS and TRISS

BACKGROUND

Early assessment of injury severity is important in trauma. Trauma scores are calculated after the fact and are useful for audit and research, but not in the emergency clinical setting. Glucose metabolism is altered in trauma, and we hypothesised that alterations in glucose and lactate levels would be an early predictor of mortality.

METHODS

Review of trauma registry data identified 1197 patients between May 2000 and September 2006 who had a trauma-team call out. Data collected included trauma scores, venous glucose (gluc), and arterial lactate (lact) on arrival. The predictive value of these variables was compared by ROC curves.

RESULTS

The mortality rate for patients with gluc >11.0mmol/L was 13.4% compared to 1.8% in those with gluc <or=11.0mmol/L (p<0.0001). Gluc had a specificity of 93.2% and a sensitivity of 37.9% for death. 13.0% of patients with lact >2.0mmol/L died, versus 2.7% with lact <or=2.0mmol/L, (p0.0003, specificity 56.8% and sensitivity 81.0%). Glucose was the better biochemical predictor of mortality compared to lactate (ROC area 0.845 and 0.716, respectively). The TRISS (trauma and injury severity score) was a very accurate predictor (ROC 0.963), whereas the ISS (injury severity score) significantly less so (ROC 0.854). There was a significant correlation between gluc, ISS, and TRISS (p 0.01), as well as lactate and ISS (p 0.01).

CONCLUSION

Glucose and lactate can predict mortality in severe trauma. The predictive value of glucose is comparable to that of ISS, and can be more easily employed in the clinical setting.

Hepatoprotection and lethality rescue by histone deacetylase inhibitor valproic acid in fatal hemorrhagic shock

BACKGROUND

Pharmacological histone deacetylase (HDAC) inhibitors, such as known anticonvulsant valproic acid (VPA), demonstrate cytoprotective effects and increase acetylation of nuclear histones, promoting transcriptional activation of deregulated genes. Therefore, we examined protective effects of VPA administration in lethal hemorrhage and analyzed the patterns of hepatic histone acetylation.

METHODS

Male Wistar Kyoto rats were pretreated with VPA (n = 10) and 2-methyl-2-pentenoic acid (2M2P), structural VPA analog with limited HDAC inhibiting activity (2M2P; n = 8), at 300 mg/kg/dose, administered subcutaneously, 24 hour and immediately before lethal, if untreated, hemorrhage was induced by removing the 60% of total blood volume. Both drugs were dissolved in normal saline (NS) and rats pretreated with corresponding volume of NS served as control group (n = 8). Time to death, the degree of histone acetylation in liver, HDAC activity and markers of cytotoxicity (alpha-glutathione S-transferase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and lactate), and apoptosis were analyzed.

RESULTS

VPA-pretreated animals demonstrated five-fold increase in survival duration. At 12 hours posthemorrhage, 70% (VPA) and 12% (2M2P) pretreated rats were alive versus 0% in NS group. Hyperacetylation of histones H2A, H3, and H4 indicated the presence of active genes and correlated with survival (VPA > 2M2P > NS). Hemorrhage-induced increases in lactate, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase were alleviated by VPA. Moreover, alpha-glutathione S-transferase release, indicative of liver damage, was completely abolished.

CONCLUSION

VPA offers considerable protection in severe hemorrhagic shock. The role of HDAC inhibition is suggested in mediating prosurvival actions of VPA.

Trauma

In terms of cost and years of potential lives lost, injury arguably remains the most important public health problem facing the United States. Care of traumatically injured patients depends on early surgical intervention and avoiding delays in the diagnosis of injuries that threaten life and limb. In the critical care phase, successful outcomes after injury depend almost solely on diligence, attention to detail, and surveillance for iatrogenic infections and complications.

Lactate in veterinary critical care: pathophysiology and management

The measurement of blood lactate in people has proven to be a useful tool in the diagnosis, monitoring, and prognosis of a wide range of clinical syndromes. Its use in small animals is increasing, and several studies have been completed that demonstrate its potential role in critical care. This article summarizes the current state of knowledge regarding the physiology and pathophysiology of lactate production and lactic acidosis; current indications and the utility of measurement in a critical care setting are described; novel applications in the evaluation of cavitary effusions are highlighted; and a guide to the therapy of lactic acidosis is presented.

Serial blood lactate concentrations in systemically ill dogs

BACKGROUND

Lactate concentration often is quantified in systemically ill dogs and interpreted based on human data. To our knowledge, there are no published clinical studies evaluating serial lactate concentrations as a prognostic indicator in ill dogs.

OBJECTIVES

Our objective was to perform a prospective study, using multivariate analysis, to determine whether serial lactate concentrations were associated with outcome in ill dogs requiring intravenous fluids.

METHODS

Eighty sick dogs had lactate concentrations evaluated, using an analyzer that measures lactate in the plasma fraction of heparinized whole blood, at 0 hours and 6 hours after initiation of treatment. Severity of illness and outcome (survivor, nonsurvivor) were determined by reviewing the patient's record 2 weeks after admission. Lactate concentrations, age, body weight, gender, and severity of illness were evaluated using multivariate analysis to determine their effects on outcome.

RESULTS

Dogs with lactate concentrations greater than the reference interval at 6 hours were 16 times (95% confidence interval = 2.32-112.71 times, P <.01) more likely not to survive compared to dogs with lactate concentrations within the reference interval. Lactate concentrations above the reference interval at 0 hours were not significantly related to outcome. However, hyperlactatemia that did not improve by > or = 50% within 6 hours was significantly associated with mortality (P = .024).

CONCLUSION

Dogs with a lactate concentration higher than the reference interval at 6 hours were more likely not to survive. These results indicate an association between lactate concentration and outcome and emphasize the importance of serial lactate concentrations in evaluating prognosis.

Occult hypoperfusion and mortality in patients with suspected infection

OBJECTIVE

To determine, in the early stages of suspected clinically significant infection, the independent relationship of the presenting venous lactate level to 28-day in-hospital mortality.

DESIGN

Prospective, observational cohort study.

SETTING

Urban, university tertiary-care hospital.

PATIENTS

One thousand two hundred and eighty seven adults admitted through the emergency department who had clinically suspected infection and a lactate measurement.

MEASUREMENTS AND RESULTS

Seventy-three [5.7% (95% CI 4.4-6.9%)] patients died in the hospital within 28 days. Lactate level was strongly associated with 28-day in-hospital mortality in univariate analysis (p<0.0001). When stratified by blood pressure, lactate remained associated with mortality (p<0.0001). Normotensive patients with a lactate level >or=4.0 mmol/l had a mortality rate of 15.0% (6.0-24%). Patients with either septic shock or lactate >or=4.0 mmol/l had a mortality rate of 28.3% (21.3-35.3%), which was significantly higher than those who had neither [mortality of 2.5% (1.6-3.4%), p<0.0001. In a model controlling for age, blood pressure, malignancy, platelet count, and blood urea nitrogen level, lactate remained strongly associated with mortality. Patients with a lactate level of 2.5-4.0 mmol/l had adjusted odds of death of 2.2 (1.1-4.2); those with lactate >or=4.0 mmol/l had 7.1 (3.6-13.9) times the odds of death. The model had good discrimination (AUC=0.87) and was well calibrated.

CONCLUSIONS

In patients admitted with clinically suspected infection, the venous lactate level predicts 28-day in-hospital mortality independent of blood pressure and adds significant prognostic information to that provided by other clinical predictors.

Hemodynamic monitoring in shock and implications for management. International Consensus Conference, Paris, France, 27-28 April 2006

OBJECTIVE

Shock is a severe syndrome resulting in multiple organ dysfunction and a high mortality rate. The goal of this consensus statement is to provide recommendations regarding the monitoring and management of the critically ill patient with shock.

METHODS

An international consensus conference was held in April 2006 to develop recommendations for hemodynamic monitoring and implications for management of patients with shock. Evidence-based recommendations were developed, after conferring with experts and reviewing the pertinent literature, by a jury of 11 persons representing five critical care societies.

DATA SYNTHESIS

A total of 17 recommendations were developed to provide guidance to intensive care physicians monitoring and caring for the patient with shock. Topics addressed were as follows: (1) What are the epidemiologic and pathophysiologic features of shock in the ICU? (2) Should we monitor preload and fluid responsiveness in shock? (3) How and when should we monitor stroke volume or cardiac output in shock? (4) What markers of the regional and micro-circulation can be monitored, and how can cellular function be assessed in shock? (5) What is the evidence for using hemodynamic monitoring to direct therapy in shock? One of the most important recommendations was that hypotension is not required to define shock, and as a result, importance is assigned to the presence of inadequate tissue perfusion on physical examination. Given the current evidence, the only bio-marker recommended for diagnosis or staging of shock is blood lactate. The jury also recommended against the routine use of (1) the pulmonary artery catheter in shock and (2) static preload measurements used alone to predict fluid responsiveness.

CONCLUSIONS

This consensus statement provides 17 different recommendations pertaining to the monitoring and caring of patients with shock. There were some important questions that could not be fully addressed using an evidence-based approach, and areas needing further research were identified.

Esophageal Doppler-guided fluid management decreases blood lactate levels in multiple-trauma patients: a randomized controlled trial

Introduction

Esophageal Doppler was confirmed as a useful non-invasive tool for management of fluid replacement in elective surgery. The aim of this study was to assess the effect of early optimization of intravascular volume using esophageal Doppler on blood lactate levels and organ dysfunction development in comparison with standard hemodynamic management in multiple-trauma patients.

Methods

This was a randomized controlled trial. Multiple-trauma patients with blood loss of more than 2,000 ml admitted to the intensive care unit (ICU) were randomly assigned to the protocol group with esophageal Doppler monitoring and to the control group. Fluid resuscitation in the Doppler group was guided for the first 12 hours of ICU stay according to the protocol based on data obtained by esophageal Doppler, whereas control patients were managed conventionally. Blood lactate levels and organ dysfunction during ICU stay were evaluated.

Results

Eighty patients were randomly assigned to Doppler and 82 patients to control treatment. The Doppler group received more intravenous colloid during the first 12 hours of ICU stay (1,667 ± 426 ml versus 682 ± 322 ml; p < 0.0001), and blood lactate levels in the Doppler group were lower after 12 and 24 hours of treatment than in the control group (2.92 ± 0.54 mmol/l versus 3.23 ± 0.54 mmol/l [p = 0.0003] and 1.99 ± 0.44 mmol/l versus 2.37 ± 0.58 mmol/l [p < 0.0001], respectively). No difference in organ dysfunction between the groups was found. Fewer patients in the Doppler group developed infectious complications (15 [18.8%] versus 28 [34.1%]; relative risk = 0.5491; 95% confidence interval = 0.3180 to 0.9482; p = 0.032). ICU stay in the Doppler group was reduced from a median of 8.5 days (interquartile range [IQR] 6 to16) to 7 days (IQR 6 to 11) (p = 0.031), and hospital stay was decreased from a median of 17.5 days (IQR 11 to 29) to 14 days (IQR 8.25 to 21) (p = 0.045). No significant difference in ICU and hospital mortalities between the groups was found.

Conclusion

Optimization of intravascular volume using esophageal Doppler in multiple-trauma patients is associated with a decrease of blood lactate levels, a lower incidence of infectious complications, and a reduced duration of ICU and hospital stays.

Is Blood Sugar the Next Lactate?

This study evaluates whether an initial blood glucose level is similarly predictive of injury severity and outcome as admission lactate in trauma patients. Between February 2004 and June 2005, we prospectively compared patients with presenting blood sugars of ≤150 mg/dL (LBS) with those with blood sugars >150 mg/dL (HBS). Fifty patients had BS above 150 mg/dL, whereas 176 patients were ≤150 mg/dL. These groups had similar demographics except for age. Injury Severity Score (ISS) of ≥15 was seen in 56.0 per cent of HBS patients versus 28.4 per cent of LBS patients (P = 0.0006). HBS patients had similar infection rates (12.0% HBS vs. 5.7% LBS, P = 0.13) but a higher mortality (30.0% HBS vs. 5.7% LBS, P < 0.0001). There was a linear relationship between ISS and BS (r2 = 0.18, P < 0.0001) and ISS and lactate (r2 = 0.17, P < 0.0001). Blood sugar trended with the lactate (r = 0.25, P = 0.0001). Hyperglycemic patients were more severely injured with higher mortality. BS correlated with lactate, and because it is easily obtainable, it may serve as a readily available predictor of injury severity and prognosis.

Reduced Heart Rate Variability: An Indicator of Cardiac Uncoupling and Diminished Physiologic Reserve in 1,425 Trauma Patients

BACKGROUND

Measurements of a patient's physiologic reserve (age, injury severity, admission lactic acidosis, transfusion requirements, and coagulopathy) reflect robustness of response to surgical insult. We have previously shown that cardiac uncoupling (reduced heart rate variability, HRV) in the first 24 hours after injury correlates with mortality and autonomic nervous system failure. We hypothesized: Deteriorating physiologic reserve correlates with reduced HRV and cardiac uncoupling.

METHODS

There were 1,425 trauma ICU patients that satisfied the inclusion criteria. Differences in mortality across categorical measurements of the domains of physiologic reserve were assessed using the chi test. The relationship of cardiac uncoupling and physiologic reserve was examined using multivariate logistic regression models for various levels of cardiac uncoupling (>0 through 28% reduced HRV in the first 24 hours).

RESULTS

Of these, 797 (55.9%) patients exhibited cardiac uncoupling. Deteriorating measures of physiologic reserve reflected increased risk of death. Measures of acidosis (admission lactate, time to lactate normalization, and lactate deterioration over the first 24 hours), coagulopathy, age, and injury severity contributed significantly to the risk of cardiac uncoupling (area under receiver operator curve, ROC=0.73). The association between deteriorating reserve and cardiac uncoupling increases with the threshold for uncoupling (ROC=0.78).

CONCLUSIONS

Reduced heart rate variability is a new biomarker reflecting the loss of command and control of the heart (cardiac uncoupling). Risk of cardiac uncoupling increases significantly as a patient's physiologic reserve deteriorates and physiologic exhaustion approaches. Cardiac uncoupling provides a noninvasive, overall measure of a patient's clinical trajectory over the first 24 hours of ICU stay.

Admission serum lactate levels do not predict mortality in the acutely injured patient

INTRODUCTION

The conventional view that admission lactate levels predict outcome in trauma patients stems from simple comparisons of mean blood levels between groups and small sample sizes. To better address this question, we performed more rigorous statistical analyses of lactate in a larger patient sample.

METHODS

We prospectively collected data on admission lactate and outcomes in 5,995 patients admitted to an urban, university-based trauma center. The ability of admission lactate to predict mortality was assessed by logistic regression, calculation of positive predictive values (PPV), and measurement of areas under receiver operating characteristic (ROC) curves.

RESULTS

Differences between survivors and nonsurvivors in means of most proposed prognosticators was again demonstrated. However, the large overlap in these variables between survivors and nonsurvivors prevented clinically useful predictions. The overall PPV of elevated lactate was only 5.4%. Even in severely injured patients (Injury Severity Score >20; mortality 23%), elevated admission lactate level was a poor predictor of outcome. ROC analyses found no useful sensitivity threshold overall or after stratification by age, sex, Glasgow Coma Scale score, revised trauma score, or mechanism of injury.

CONCLUSIONS

This large retrospective examination of admission lactate levels failed to show useful predictive accuracy for hospital death. Serum lactate levels need not be obtained routinely but can be reserved for patients who will be admitted to the intensive care unit and/or require an emergency operation.

Lactic acidosis: from sour milk to septic shock

Lactic acidosis is frequently encountered in the intensive care unit. It occurs when there is an imbalance between production and clearance of lactate. Although lactic acidosis is often associated with a high anion gap and is generally defined as a lactate level >5 mmol/L and a serum pH <7.35, the presence of hypoalbuminemia may mask the anion gap and concomitant alkalosis may raise the pH. The causes of lactic acidosis are traditionally divided into impaired tissue oxygenation (Type A) and disorders in which tissue oxygenation is maintained (Type B). Lactate level is often used as a prognostic indicator and may be predictive of a favorable outcome if it normalizes within 48 hours. The routine measurement of serum lactate, however, should not determine therapeutic interventions. Unfortunately, treatment options remain limited and should be aimed at discontinuation of any offending drugs, treatment of the underlying pathology, and maintenance of organ perfusion. The mainstay of therapy of lactic acidosis remains prevention.

Admission Hyperglycemia and Other Risk Factors as Predictors of Hospital Mortality in a Medical ICU Population

BACKGROUND

Tight glycemic control is recommended for patients in the ICU, as hyperglycemia is associated with increased morbidity and mortality.

DESIGN

Observational cohort of patients admitted to a 12-bed, inner-city, medical ICU (MICU).

SUBJECTS

A total of 1,185 of 1,506 patients from July 1, 1999, to December 31, 2002, selected based on a diagnosis other than diabetic ketoacidosis or glycemia > 280 mg/dL or < 80 mg/dL.

PURPOSES

To determine if the highest serum glucose level within 24 h after ICU admission is associated with increased hospital mortality when adjusted for confounders.

MEASUREMENTS

Age, gender, race, worst values within 24 h after ICU admission to construct the acute physiology and chronic health evaluation (APACHE) II score, and highest glucose within 24 h after ICU admission. Hospital mortality was the primary outcome. Admitting diagnosis, MICU length of stay (LOS), and hospital LOS were obtained. Glucose, albumin (n = 867), and lactic acid (n = 319) were stratified for analysis.

ANALYSIS

Univariate analysis identified factors included in the multivariate model.

RESULTS

Patients were predominantly African-American (79%) and men (56%; mean age, 49.2 years). The mean ICU admission highest glucose level was 139 +/- 43.7 mg/dL (+/- SD). MICU LOS and hospital LOS were 6.2 days and 12.9 days, respectively, and 50% of patients received mechanical ventilation. MICU and hospital mortality were 18% and 20%, respectively; standardized mortality ratio was 66%. On univariate analysis, survivors (n = 945) and nonsurvivors (n = 240) showed APACHE II score, mechanical ventilation, hypoalbuminemia, lactic acidemia, and logistic organ dysfunction system score to be hospital mortality predictors; however, the highest admission serum glucose level was not. Logistic regression estimated APACHE II score/per point (odds ratio, 1.06; 95% confidence interval, 1.02 to 1.11), mechanical ventilation (odds ratio, 3.06; 95% confidence interval, 1.34 to 6.96), severe hypoalbuminemia (< 2 g/dL) [odds ratio, 2.98; 95% confidence interval, 1.3 to 7.02], and severe lactic acidemia (> or = 8 mmol/L) [odds ratio, 7.3; 95% confidence interval, 2.14 to 24.9], but not ICU admission hyperglycemia, to be associated with hospital mortality.

CONCLUSIONS

Conventional factors of disease severity, but not highest glucose value during the first 24 h after ICU admission, predict hospital mortality in an inner-city MICU.

Ubiquitin reduces fluid shifts after traumatic brain injury

BACKGROUND

Ubiquitin has well-described intracellular properties. Recent data also suggest pleiotropic effects of extracellular ubiquitin, including induction of apoptosis, regulation of immune functions, and therapeutic potential during fluid resuscitation from severe trauma. However, the actions of exogenous ubiquitin after traumatic brain injury (TBI) are unknown.

METHODS

Series 1: Thirty-five minutes after TBI and hemorrhage, 1.5 mg ubiquitin/kg (n = 5) or albumin (n = 5) intravenous was followed by fluid resuscitation to maintain mean arterial and cerebral perfusion pressure. Series 2: Ubiquitin (n = 5) or vehicle (n = 6) was administered after TBI only. Ubiquitin was measured with enzyme-linked immunosorbent assay in serum, urine (series 1), and cerebrospinal fluid (series 2) for 300 minutes.

RESULTS

Series 1: After intravenous bolus, serum ubiquitin peaked at t = 45 minutes with a half-life of 54 minutes. Recovery in urine was 10%. With albumin versus ubiquitin, 85% more resuscitation fluid was required to stabilize systemic and cerebral hemodynamics (P < .05 for t = 150 to 300 minutes), but hematocrit was similar. With albumin there were progressive increases in intracranial pressure, peak inspiratory pressure, and decreases in oxygenation. All were significantly attenuated by ubiquitin (all P < .05 vs albumin). Series 2: Intravenous ubiquitin altered cerebrospinal fluid ubiquitin with an increased time to peak (t = 88 +/- 13 min vs 45 +/- 7 min, P < .05) and area under the concentration-time curve (82 +/- 22 vs 23 +/- 11 microg/min(1)/mL(-1), P < .05).

CONCLUSIONS

After TBI, intravenous ubiquitin crossed the blood-brain barrier and significantly reduced third spacing of fluid into the brain and lung during resuscitation.

Bench-to-bedside review: oxygen debt and its metabolic correlates as quantifiers of the severity of hemorrhagic and post-traumatic shock

Evidence is increasing that oxygen debt and its metabolic correlates are important quantifiers of the severity of hemorrhagic and post-traumatic shock and and may serve as useful guides in the treatment of these conditions. The aim of this review is to demonstrate the similarity between experimental oxygen debt in animals and human hemorrhage/post-traumatic conditions, and to examine metabolic oxygen debt correlates, namely base deficit and lactate, as indices of shock severity and adequacy of volume resuscitation. Relevant studies in the medical literature were identified using Medline and Cochrane Library searches. Findings in both experimental animals (dog/pig) and humans suggest that oxygen debt or its metabolic correlates may be more useful quantifiers of hemorrhagic shock than estimates of blood loss, volume replacement, blood pressure, or heart rate. This is evidenced by the oxygen debt/probability of death curves for the animals, and by the consistency of lethal dose (LD)_25,50 points for base deficit across all three species. Quantifying human post-traumatic shock based on base deficit and adjusting for Glasgow Coma Scale score, prothrombin time, Injury Severity Score and age is demonstrated to be superior to anatomic injury severity alone or in combination with Trauma and Injury Severity Score. The data examined in this review indicate that estimates of oxygen debt and its metabolic correlates should be included in studies of experimental shock and in the management of patients suffering from hemorrhagic shock.