Acid-base disorders as predictors of early outcomes in major trauma in a resource limited setting: An observational prospective study

Estimation of blood lactate and bicarbonate levels after stored blood transfusion to predict ICU admission in patients undergoing major head and neck surgeries: A prospective observational study

Background and Aims

Major head neck surgeries are often associated with major blood loss requiring blood transfusion. However, in spite of transfusion, patients usually suffer adverse postoperative outcomes. Biomarkers can help in identifying such events early. This observational study was conducted to compare blood lactate and bicarbonate levels as predictors of adverse postoperative outcomes.

Materials and Methods

Forty-eight adult American Society of Anesthesiologists Physical Status I-III patients met the inclusion criteria. Intraoperative blood loss was managed with stored blood transfusion as per transfusion trigger. Blood lactate and bicarbonate levels were measured preoperatively (Tbas), at the immediate postoperative period (T0), and at 8 h (T8), 16 h (T16), and 24 h (T24) postoperatively. Outcomes such as need for intensive care unit (ICU) admission, length of ICU stay, intraoperative blood transfusion, re-exploration rate, and mortality were recorded.

Results

Blood transfusions and ICU admissions were required in 19 (39.6%) and 24 (50%) patients, respectively. Lactate levels of patients requiring blood transfusion and admission to ICU rose significantly from their baseline (1.30 ± 0.41 mmol/l) to 2.80 ± 1.14 mmol/l at the immediate postoperative period, which fell to 2.06 ± 0.78 mmol/l at 24 h postoperatively, compared to other patients who did not require transfusion and ICU admission (P < 0.001). The bicarbonate value did not show any significant change from its baseline (22.68 ± 1.83 mEq/l) at all time points (P = 0.8). In addition, no significant difference was noted regarding ICU admissions (P = 0.659) or blood transfusions (P = 0.788).

Conclusions

Following major head and neck surgeries, blood lactate level is a good predictor, but bicarbonate is a poor predictor of the need for blood transfusions and ICU admission. Intraoperative blood transfusion failed to prevent rise in blood lactate level, which is taken as a surrogate marker of tissue hypoxia.

Predictors of Mortality in Ruptured Abdominal Aortic Aneurysms

Introduction The outcome of a ruptured abdominal aortic aneurysm (AAA) without any interventions is close to uniformly fatal. The Society for Vascular Surgery suggests a door-to-intervention time of less than 90 minutes in a patient with a ruptured AAA. Admission factors associated with poor outcomes in ruptured AAAs include hypotension, renal insufficiency, severe anemia, advanced age, and cardiac arrest. Patients who are particularly at high risk for open AAA repair may be candidates for endovascular repair, which may decrease mortality. This study aimed to assess the relationship between systolic blood pressure (SBP) and serum bicarbonate levels in predicting mortality in patients with ruptured AAAs. Methods This retrospective study was performed using the United States Collaborative Network of 57 academic medical centers/healthcare organizations in the TriNetX database. A total of 4,226 patients with ruptured AAAs were identified. Patients were categorized based on SBP of ≤90 mmHg, any SBP, or >90 mmHg and further stratified by bicarbonate levels. Rounded cutoffs of the bicarbonate ranges (<10, 10.01-15; 15.01-20, >20.01) were chosen for interpretative purposes. Mortality outcome was assessed within 90 days after presentation for the ruptured AAA. Results After exclusions, 4,174 patients presented with ruptured AAA between September 30, 2003, and September 30, 2023, in the database. Overall, 90-day mortality in any SPB cohort was 28%. Patients who presented with a ruptured AAA with an SBP ≤ 90 had a 46.3% mortality. Those who presented with a SBP > 90 had a 20.1% mortality. Additionally, as bicarbonate levels decreased, mortality increased within each SBP group. Conclusions Early recognition and intervention are critical for survival in patients with ruptured AAAs. Metabolic acidosis is an important marker of the severity of hemorrhage in these patients. In this large cohort study of ruptured AAAs, mortality increases significantly with hypotension and metabolic acidosis, represented by lower bicarbonate levels. Abnormalities in the serum bicarbonate may be seen before severe changes in vital signs in hemorrhaging patients. Early recognition of metabolic acidosis may lead to earlier life-saving interventions in patients with ruptured AAAs.

Bicarbonate and Serum Lab Markers as Predictors of Mortality in the Trauma Patient

Introduction

Severe trauma-induced blood loss can lead to metabolic acidosis, shock, and death. Identification of abnormalities in the bicarbonate and serum markers may be seen before frank changes in vital signs in the hemorrhaging trauma patient, allowing for earlier lifesaving interventions. In this study the author aimed to evaluate the usefulness of serum bicarbonate and other lab markers as predictors of mortality in trauma patients within 30 days after injury.

Methods

This retrospective, propensity-matched cohort study used the TriNetX database, covering approximately 92 million patients from 55 healthcare organizations in the United States, including 3.8 million trauma patients in the last two decades. Trauma patients were included if they had lab measurements available the day of the event. The analysis focused on mortality within 30 days post-trauma in comparison to measured lab markers. Cohorts were formed based on ranges of bicarbonate, lactate, and base excess levels.

Results

Before propensity score matching, a total of 1,275,363 trauma patients with same-day bicarbonate, lactate, or base excess labs were identified. A significant difference in mortality was found across various serum bicarbonate lab ranges compared to the standard range of 21-27 milliequivalents per liter (mEq/L), post-propensity score matching. The relative risk of death was 6.806 for bicarbonate ≤5 mEq/L; 8.651 for 6-10; 6.746 for 11-15; 2.822 for 16-20; and 1.015 for bicarbonate ≥28. Serum lactate also displayed significant mortality outcomes when compared to a normal level of ≤2 millimoles per liter. Base excess showed similar significant correlation at different values compared to a normal base excess of -2 to 2 mEq/L.

Conclusion

This study, approximately 100 times larger than prior studies, associated lower bicarbonate levels with increased mortality in the trauma patient. While lactate and base excess offer prognostic value, lower bicarbonate values have a higher relative risk of death. The greater predictive value of bicarbonate and accessibility during resuscitations suggests that it may be the superior prognostic marker in trauma.

The Association Between Serum Lactate Concentration, Base Deficit, and Mortality in Polytrauma Patients as a Prognostic Factor: An Observational Study

Introduction

In polytrauma patients, it is crucial to identify the severity of the injuries to ensure patient safety and survival. Polytrauma leads to hypotension and hypoperfusion, which results in an anaerobic metabolism with acidosis and a decrease in base excess. Thus, blood lactate levels above a certain threshold indicate the existence of global tissue hypoxia, which is a precursor to shock and multiple organ dysfunction syndrome (MODS). The serum lactate and base deficit (BD) levels are used in polytrauma patients as measures of damage severity and resuscitation endpoints and as a way to evaluate therapy efficacy and to predict outcomes. Thus, arterial blood gas analysis is of great value in assessing the status and prognosis of patients with polytrauma. There are few comparative studies on the predictive values of these markers in trauma patients. To determine which measure can more accurately predict the prognosis of polytrauma patients, the present study investigated the predictive values of mortality of these indicators for mortality within 48 hours of admission to the emergency room (ER) in patients with polytrauma.

Methods

This prospective study was designed for a single tertiary care center in northern India. We included 90 patients with polytrauma who were between the ages of 18 and 70 years, with the exception of pregnant women, who presented to the ER within six hours of injury with an injury severity score (ISS) >16, serum lactate level >2.0 mmol/L, and BD -4.0 mEq/L at the time of admission. If the patient's ISS was >16 at the time of ER presentation, arterial blood samples were drawn to determine the serum lactate and BD level at the time of admission and at 12, 24, and 48 hours intervals after ER admission. The primary outcome was the change in serum lactate and BD level in polytrauma. The secondary outcomes were an association of serum lactate and BD with mortality and the correlation between serum lactate with the BD and ISS with mortality of polytrauma patients. The timing of all outcome assessments was at 48 hours after each patient's ER admission.

Results

Lactate clearance from 0-12 hours (t = 2.28, p <0.05), 0-24 hours (t = 6.01, p <0.001), and 0-48 hours (t = 7.98, p <0.001) and a correction in BD from 0-24 (t = 2.68, p <0.01 ) and 0-48 hours (t = 5.46, p <0.001) were significantly higher in nonsurvivors as compared with survivors. In survivors and nonsurvivors, mean serum lactate levels (2.46 ± 1.46 versus 4.15 ± 2.99, t = 3.31, p <0.001, 95%Cl) and mean BD (-3.17 ± 2.58 versus -6.5 ± 4.91, t = 3.86, p <0.001, 95%CI) had a statistically significant difference. The serum lactate and BD levels at time of ER admission (r L0, BD0 = -0.765, p <0.01) and 48 hours after ER admission (r L48, BD 48 = -0.652, p <0.001) were highly negatively correlated.

Conclusion

In polytrauma patients, serum lactate and BD are simple, quick, and independent biochemical predictors of 48-hour mortality, and this single arterial blood test would thereby improve decision-making for resuscitation effectiveness. Prolonged lactate and BD normalization time were associated with higher mortality. Serum lactate and BD are negatively correlated. A higher ISS at admission was associated with a higher incidence of mortality in polytrauma patients.

Elevated Admission Base Deficit Is Associated with a Complex Dynamic Network of Systemic Inflammation Which Drives Clinical Trajectories in Blunt Trauma Patients

We hypothesized that elevated base deficit (BD) ≥ 4 mEq/L upon admission could be associated with an altered inflammatory response, which in turn may impact differential clinical trajectories. Using clinical and biobank data from 472 blunt trauma survivors, 154 patients were identified after excluding patients who received prehospital IV fluids or had alcohol intoxication. From this subcohort, 84 patients had a BD ≥ 4 mEq/L and 70 patients with BD < 4 mEq/L. Three samples within the first 24 h were obtained from all patients and then daily up to day 7 after injury. Twenty-two cytokines and chemokines were assayed using Luminex™ and were analyzed using two-way ANOVA and dynamic network analysis (DyNA). Multiple mediators of the innate and lymphoid immune responses in the BD ≥ 4 group were elevated differentially upon admission and up to 16 h after injury. DyNA revealed a higher, sustained degree of interconnectivity of the inflammatory response in the BD ≥ 4 patients during the initial 16 h after injury. These results suggest that elevated admission BD is associated with differential immune/inflammatory pathways, which subsequently could predispose patients to follow a complicated clinical course.

Anion gap as a prognostic tool for risk stratification in critically ill patients - a systematic review and meta-analysis

BACKGROUND

Lactate concentration is a robust predictor of mortality but in many low resource settings facilities for its analysis are not available. Anion gap (AG), calculated from clinical chemistry results, is a marker of metabolic acidosis and may be more easily obtained in such settings. In this systematic review and meta-analysis we investigated whether the AG predicts mortality in adult patients admitted to critical care settings.

METHODS

We searched Medline, Embase, Web of Science, Scopus, The Cochrane Library and regional electronic databases from inception until May 2016. Studies conducted in any clinical setting that related AG to in-hospital mortality, in-intensive care unit mortality, 31-day mortality or comparable outcome measures were eligible for inclusion. Methodological quality of included studies was assessed using the Quality in Prognostic Studies tool. Descriptive meta-analysis was performed and the I(2) test was used to quantify heterogeneity. Subgroup analysis was undertaken to identify potential sources of heterogeneity between studies.

RESULTS

Nineteen studies reporting findings in 12,497 patients were included. Overall, quality of studies was poor and most studies were rated as being at moderate or high risk of attrition bias and confounding. There was substantial diversity between studies with regards to clinical setting, age and mortality rates of patient cohorts. High statistical heterogeneity was found in the meta-analyses of area under the ROC curve (I(2) = 99 %) and mean difference (I(2) = 97 %) for the observed AG. Three studies reported good discriminatory power of the AG to predict mortality and were responsible for a large proportion of statistical heterogeneity. The remaining 16 studies reported poor to moderate ability of the AG to predict mortality. Subgroup analysis suggested that intravenous fluids affect the ability of the AG to predict mortality.

CONCLUSION

Based on the limited quality of available evidence, a single AG measurement cannot be recommended for risk stratification in critically ill patients. The probable influence of intravenous fluids on AG levels renders the AG an impractical tool in clinical practice. Future research should focus on increasing the availability of lactate monitoring in low resource settings.

PROSPERO REGISTRATION NUMBER

CRD42015015249 . Registered on 4th February 2015.