Can base excess and anion gap predict lactate level in diagnosis of septic shock?

Relationship of Admission Serum Anion Gap and Prognosis of Critically Ill Patients: A Large Multicenter Cohort Study

Background

There were controversies over the relationship between Anion gap (AG) and mortality in critically ill patients. Therefore, a large multicenter cohort study was conducted to evaluate the association of AG and mortality in large-scale intensive care units (ICUs) patients.

Methods

This retrospective cohort study included adult ICU patients enrolled from eICU Collaborative Research Database. According to initial serum AG upon ICU admission, patients were divided into three groups: AG < 8 mmol/L, 8 ≤ AG ≤ 16 mmol/L, and AG > 16 mmol/L. Logistic regression models were built to investigate the association between serum AG and ICU and hospital mortalities. Serum AG was added into Acute Physiology and Chronic Health Evaluation (APACHE) IV score and the model discrimination was assessed by the area under the curve (AUC) of receiver operating characteristic curves. The relationship between serum AG and mortalities in patients with different acid-base status and serum lactate were also evaluated. An external validation was performed with the Critical care database comprising patients with infection at Zigong Fourth People's Hospital.

Results

A total of 8520 patients entered the final cohort. There are 42 patients with serum AG < 8 mmol/L, 3238 patients with 8 ≤ AG ≤ 16 mmol/L, and 5240 patients with AG > 16 mmol/L. Serum AG > 16 mmol/L is related with increased ICU mortality (odds ratio [OR], 1.530; 95% confidence interval [CI], 1.305-1.794) and hospital mortality (OR, 1.618; 95% CI, 1.415-1.849), compared with 8 ≤ AG ≤ 16 mmol/L. Adding Serum AG to APACHE IV score could statistically improve the prediction of ICU (0.770 [0.761-0.779] to 0.774 [0.765-0.783], P = 0.001) and hospital mortalities (0.756 [0.747-0.765] to 0.761 [0.751-0.770], P = 0.012). The associations between serum AG and mortalities remain robust in patients with different acid-base statuses and serum lactate. The findings are validated in the external cohort.

Conclusions

Initial serum AG > 16 mmol/L after ICU admission is associated with increased mortality in critically ill patients.

DeepBiomarker: Identifying Important Lab Tests from Electronic Medical Records for the Prediction of Suicide-Related Events among PTSD Patients

Identifying patients with high risk of suicide is critical for suicide prevention. We examined lab tests together with medication use and diagnosis from electronic medical records (EMR) data for prediction of suicide-related events (SREs; suicidal ideations, attempts and deaths) in post-traumatic stress disorder (PTSD) patients, a population with a high risk of suicide. We developed DeepBiomarker, a deep-learning model through augmenting the data, including lab tests, and integrating contribution analysis for key factor identification. We applied DeepBiomarker to analyze EMR data of 38,807 PTSD patients from the University of Pittsburgh Medical Center. Our model predicted whether a patient would have an SRE within the following 3 months with an area under curve score of 0.930. Through contribution analysis, we identified important lab tests for suicide prediction. These identified factors imply that the regulation of the immune system, respiratory system, cardiovascular system, and gut microbiome were involved in shaping the pathophysiological pathways promoting depression and suicidal risks in PTSD patients. Our results showed that abnormal lab tests combined with medication use and diagnosis could facilitate predicting SRE risk. Moreover, this may imply beneficial effects for suicide prevention by treating comorbidities associated with these biomarkers.

Correlation of the Changing Trends of ScvO2, Serum Lactate, Standard Base Excess and Anion Gap in Patients with Severe Sepsis and Septic Shock Managed by Early Goal Directed Therapy (EGDT): A Prospective Observational Study

BACKGROUND

To observe the correlation of central venous oxygen saturation (ScvO₂), serum lactate, standard base excess (SBE), and anion gap (AG) in septic and septic shock patients resuscitated with early goal-directed therapy (EGDT).

MATERIALS AND METHODS

A review was made of 130 severe septic shock patients (15-65 years) according to the consensus conference criteria admitted in intensive care unit. Blood samples were obtained from arterial and central venous line for ScvO_2, serum lactate, SBE, and AG on admission and after achieving all aims of EGDT i.e.; mean arterial pressure >65 mmHg, central venous pressure = 8-12 mmHg, ScvO₂ >70%, and urine output >0.5 mL.kg^-1.h^-1, and on 12 and 24 h. The statistical analysis was done using SPSS for windows version 16 software. For comparison, Pearson test was used. A P < 0.05 was considered as statistically significant.

RESULTS

There were a positive correlation between ScvO₂ and SBE, a negative correlation between ScvO₂ and AG, a negative correlation between ScvO₂ and lactate, a negative correlation between SBE and AG, a negative correlation between AG and lactate, and a negative correlation between SBE and lactate. The ScvO₂ was initially low but was in an improving trend after a resuscitative period, SBE was initially low and correction of SBE was linear. AG was high in the beginning and goes on decreasing after resuscitation. Lactate level was also high initially and in decreasing trend after a resuscitative period.

CONCLUSIONS

ScvO₂ and SBE are correlated and can be used as a surrogate marker. ScvO₂ and AG are related but not absolutely codependent. ScvO₂ and lactate are correlated but they are not absolutely codependent. SBE and AG are correlated and can be used as a surrogate marker. AG and lactate are not related to each other. Hence, AG cannot be considered as a surrogate for lactate testing. SBE and lactate are related and can be used as a surrogate marker.

Significance of lactate clearance in septic shock patients with high bilirubin levels

Lactate clearance is affected by hepatic function. However, it is unclear whether the association between hepatic dysfunction and lactate clearance can act as a prognostic marker of clinical outcomes in patients with septic shock. We aimed to evaluate the association between lactate clearance and mortality in two cohorts of septic shock patient who had hepatic dysfunction based on their total serum bilirubin levels (TBIL). Lactate clearance at 24 h after the onset of septic shock was analyzed using two cohorts, sub-categorized into two groups based on TBIL: < 2 mg/dL and ≥ 2 mg/dL. In the derivation cohort, lactate clearance was lower in non-survivors than in survivors with TBIL ≥ 2 mg/dL, while there was no significant difference in lactate clearance between non-survivors and survivors with TBIL < 2 mg/dL. Multivariate logistic regression analysis revealed that increased lactate clearance was significantly associated with decreased 28-day mortality in the TBIL ≥ 2 mg/dL group (10% lactate clearance, adjusted odds ratio [OR]: 0.88, 95% confidence interval (CI): 0.80-0.97, P = 0.0075), Creatinine level ≥ 2 mg/dL group (adjusted OR: 0.88, 95% CI: 0.81-0.95, P = 0.00069) and APACHE II score ≥ 35 group (adjusted OR: 0.93, 95% CI: 0.87-0.98, P = 0.013). In the validation cohort, lactate clearance was lower in non-survivors than in survivors with TBIL ≥ 2 mg/dL, while no significant difference in lactate clearance was observed between non-survivors and survivors with TBIL < 2 mg/dL. Increased lactate clearance was significantly associated with decreased 28-day mortality in the TBIL ≥ 2 mg/dL group (10% lactate clearance, adjusted OR: 0.89, 95% CI: 0.83-0.96, P = 0.0038) and the association was just about significant in APACHE II score ≥ 35 group (adjusted OR: 0.86, 95% CI: 0.74-1.00, P = 0.051). In conclusion, increased lactate clearance in septic shock patients with hepatic dysfunction (TBIL ≥ 2 mg/dL) or high severity (APACHE II score ≥ 35) was associated with decreased 28-day mortality.

Lactate, bicarbonate and anion gap for evaluation of patients presenting with sepsis to the emergency department: A prospective cohort study

OBJECTIVE

A serum lactate level >2 mmol/L has been chosen as the preferred cut-off value for screening of patients with suspected sepsis. In patients with suspected sepsis presenting to the ED, we aimed to determine the outcomes of patients with initial lactate levels ≤2 mmoL/L, but abnormal bicarbonate or anion gaps (AGs).

METHODS

This prospective cohort study enrolled patients from an adult tertiary referral hospital who presented with suspected sepsis. The predictive value of lactate, bicarbonate and the AG for intensive care unit (ICU) admission and death at hospital discharge were evaluated using area under the receiver operating characteristic curves (AUROC).

RESULTS

There were 441 patients with suspected sepsis enrolled from February 2016 to June 2017. There were 96 (22.0%) patients who were admitted to the ICU and at hospital discharge, 42 (9.6%) patients had died. There was no statistically significant difference between the AUROCs of lactate or bicarbonate level or AG to predict ICU admission (P = 0.17). There was no statistically significant difference between the AUROCs of lactate or bicarbonate level or AG to predict mortality at hospital discharge (P = 0.44). Among the 73 patients with normal lactate levels, but abnormal bicarbonate or AG, there were seven (9.6%) deaths.

CONCLUSIONS

A normal lactate level alone should not be used to exclude life-threatening sepsis. Patients with metabolic acidosis characterised by low bicarbonate or high AG levels, but with normal lactate levels, have high rates of ICU requirement and mortality and should also be considered for early, aggressive therapy.