The Prognostic Value of Prehospital Blood Lactate Levels to Predict Early Mortality in Acute Cardiovascular Disease

Prehospital blood gas analyses in acute patients treated by a ground-based physician-manned emergency unit: a cohort study

BACKGROUND

The prehospital patients treated by ambulances and mobile emergency care units (MECU) are potentially critically ill or injured. Knowing the risks of serious outcomes in these patients is important for guiding their treatment. Some settings allow for prehospital arterial blood gas analyses. This study aimed to assess the outcomes of prehospital patients in relation to their prehospitally measured lactate, pH, and CO2 levels. The primary outcome was 7-day mortality.

METHODS

This register-based cohort study included patients with one or more prehospital blood gas analyses during their prehospital treatment by a physician-manned MECU, from January 2015 to December 2018. The blood samples were analyzed on an ABL90 Flex analyzer. Absolute values with percentages and odds ratios (OR) with 95% confidence intervals (CI) were calculated for the primary and secondary outcomes within prespecified subgroups.

RESULTS

The study included 745 patients, with an overall 7-day mortality rate of 20.0%.

LACTATE LEVEL

The 7-day mortality rates were 11.5% in patients with normal lactate levels (< 2.0 mmol/L), 14.4% with intermediate lactate levels (2.0-3.9 mmol/L), and 33.0% with high lactate levels (≥ 4.0 mmol/L). This corresponded to an OR of 1.30 (95% CI: 0.75-2.24) in the intermediate lactate group (2.0-3.9 mmol/L) and an OR of 3.77 (95% CI: 2.44-5.85) in the high lactate group (≥ 4.0 mmol/L), compared to the reference group with normal lactate.

PH LEVEL

The ORs of 7-day mortality rates were 4.82 (95% CI: 3.00-7.75) in patients with blood pH of < 7.35 and 1.33 (95% CI: 0.65-2.72) in patients with blood pH > 7.45, compared to the reference group with normal pH (7.35-7.45). CO2 LEVEL : The ORs of 7-day mortality rates were 2.54 (95% CI: 1.45-4.46) in patients with blood CO2 of < 4.3 kPa and 2.62 (95% CI: 1.70-4.03) in patients with blood CO2 > 6.0 kPa, compared to the reference group with normal CO2 (4.3-6.0 kPa).

CONCLUSIONS

This study found a strong correlation between increasing 7-day mortality rates and high blood lactate levels, low levels of pH, and abnormal CO2 blood levels, in prehospital patients undergoing prehospital blood analysis.

Prehospital acute life-threatening cardiovascular disease in elderly: an observational, prospective, multicentre, ambulance-based cohort study

OBJECTIVE

The aim was to explore the association of demographic and prehospital parameters with short-term and long-term mortality in acute life-threatening cardiovascular disease by using a hazard model, focusing on elderly individuals, by comparing patients under 75 years versus patients over 75 years of age.

DESIGN

Prospective, multicentre, observational study.

SETTING

Emergency medical services (EMS) delivery study gathering data from two back-to-back studies between 1 October 2019 and 30 November 2021. Six advanced life support (ALS), 43 basic life support and five hospitals in Spain were considered.

PARTICIPANTS

Adult patients suffering from acute life-threatening cardiovascular disease attended by the EMS.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was in-hospital mortality from any cause within the first to the 365 days following EMS attendance. The main measures included prehospital demographics, biochemical variables, prehospital ALS techniques used and syndromic suspected conditions.

RESULTS

A total of 1744 patients fulfilled the inclusion criteria. The 365-day cumulative mortality in the elderly amounted to 26.1% (229 cases) versus 11.6% (11.6%) in patients under 75 years old. Elderly patients (≥75 years) presented a twofold risk of mortality compared with patients ≤74 years. Life-threatening interventions (mechanical ventilation, cardioversion and defibrillation) were also related to a twofold increased risk of mortality. Importantly, patients suffering from acute heart failure presented a more than twofold increased risk of mortality.

CONCLUSIONS

This study revealed the prehospital variables associated with the long-term mortality of patients suffering from acute cardiovascular disease. Our results provide important insights for the development of specific codes or scores for cardiovascular diseases to facilitate the risk of mortality characterisation.

Accuracy of a point-of-care blood lactate measurement device in a prehospital setting

Point-of-care blood lactate is a promising prognostic biomarker of short-term mortality risk. Portable lactate meters need validation in the prehospital setting before widespread implementation and it is unknown whether the mode of sampling (arterial, capillary or venous) matters. This study aims to compare the StatStrip Xpress Lactate Meter's (SSX) accuracy to a validated blood gas analyser, ABL90 FLEX (ABL90), in arterial samples in the prehospital environment and to determine if lactate levels measured in venous and capillary blood samples are sufficiently accurate compared to arterial lactate levels. Patients with arterial samples drawn by the prehospital anaesthesiologist for any reason were eligible for inclusion. Simultaneously, three blood samples (arterial, capillary and venous) were analysed on SSX and arterial blood on ABL90. Measurements of agreements were evaluated by Lin's concordance correlations coefficient (CCC) and Bland-Altman Plots. One-hundred-and-eleven patients were included. SSX showed good accuracy compared to ABL90 in arterial samples with a CCC of 0.92 (95% CI 0.90-0.94). Compared to the arterial samples measured on ABL90, venous samples analysed on SSX showed higher agreement than capillary samples analysed on SSX with CCCs of 0.88 (95% CI 0.85-0.91) and 0.79 (95% CI 0.72-0.85), respectively. Bland-Altman plots showed that SSX lactate measurements in arterial, venous and capillary blood samples all had systematically negative biases compared to ABL90. We conclude that the SSX is accurate in our prehospital setting. Venous samples should be preferred over capillary samples, when arterial samples cannot be obtained.

Influence of Maternal Exercise on Glucose and Lipid Metabolism in Offspring Stem Cells: ENHANCED by Mom

CONTEXT

Recent preclinical data suggest exercise during pregnancy can improve the metabolic phenotype not only of the mother, but of the developing offspring as well. However, investigations in human offspring are lacking.

OBJECTIVE

To characterize the effect of maternal aerobic exercise on the metabolic phenotype of the offspring's mesenchymal stem cells (MSCs).

DESIGN

Randomized controlled trial.

SETTING

Clinical research facility.

PATIENTS

Healthy female adults between 18 and 35 years of age and ≤ 16 weeks' gestation.

INTERVENTION

Mothers were randomized into 1 of 2 groups: aerobic exercise (AE, n = 10) or nonexercise control (CTRL, n = 10). The AE group completed 150 minutes of weekly moderate-intensity exercise, according to American College of Sports Medicine guidelines, during pregnancy, whereas controls attended stretching sessions.

MAIN OUTCOME MEASURES

Following delivery, MSCs were isolated from the umbilical cord of the offspring and metabolic tracer and immunoblotting experiments were completed in the undifferentiated (D0) or myogenically differentiated (D21) state.

RESULTS

AE-MSCs at D0 had an elevated fold-change over basal in insulin-stimulated glycogen synthesis and reduced nonoxidized glucose metabolite (NOGM) production (P ≤ 0.05). At D21, AE-MSCs had a significant elevation in glucose partitioning toward oxidation (oxidation/NOGM ratio) compared with CTRL (P ≤ 0.05). Immunoblot analysis revealed elevated complex I expression in the AE-MSCs at D21 (P ≤ 0.05). Basal and palmitate-stimulated lipid metabolism was similar between groups at D0 and D21.

CONCLUSIONS

These data provide evidence of a programmed metabolic phenotype in human offspring with maternal AE during pregnancy.

Correlation between Emergency Medical Services Suspected COVID-19 Patients and Daily Hospitalizations

Objective: We sought to determine if Emergency Medical Services (EMS) identified Persons Under Investigation (PUI) for COVID-19 are associated with hospitalizations for COVID-19 disease for the purposes of serving as a potential early indicator of hospital surge. Methods: A retrospective analysis was conducted using data from the Maryland statewide EMS electronic medical records and daily COVID-19 hospitalizations from March 13, 2020 through July 31, 2020. All unique EMS patients who were identified as COVID-19 PUIs during the study period were included. Descriptive analysis was performed. The Box-Jenkins approach was used to evaluate the relationship between EMS transports and daily new hospitalizations. Separate Auto Regressive Integrated Moving Average (ARIMA) models were constructed to transform the data into a series of independent, identically distributed random variables. Fit was measured using the Akaike Information Criterion (AIC). The Box-Ljung white noise test was utilized to ensure there was no autocorrelation in the residuals. Results: EMS units in Maryland identified a total of 26,855 COVID-19 PUIs during the 141-day study period. The median patient age was 62 years old, and 19,111 (71.3%) were 50 years and older. 6,886 (25.6%) patients had an abnormal initial pulse oximetry (<92%). A strong degree of correlation was observed between EMS PUI transports and new hospitalizations. The correlation was strongest and significant at a 9-day lag from time of EMS PUI transports to new COVID-19 hospitalizations, with a cross correlation coefficient of 0.26 (p < .01). Conclusions: A strong correlation between EMS PUIs and COVID-19 hospitalizations was noted in this state-wide analysis. These findings demonstrate the potential value of incorporating EMS clinical information into the development of a robust syndromic surveillance system for COVID-19. This correlation has important utility in the development of predictive tools and models that seek to provide indicators of an impending surge on the healthcare system at large.

Accuracy of prehospital point-of-care lactate in early in-hospital mortality

BACKGROUND

Emergency medical services (EMS) routinely face complex scenarios where decisions should be taken with limited clinical information. The development of fast, reliable and easy to perform warning biomarkers could help in such decision-making processes. The present study aims at characterizing the validity of point-of-care lactate (pLA) during prehospital tasks for predicting in-hospital mortality within two days after the EMS assistance.

MATERIALS AND METHODS

Prospective, multicentric, ambulance-based and controlled observational study without intervention, including six advanced life support and five hospitals. The pLA levels were recorded during EMS assistance of adult patients. The validity of pLA to determine the in-hospital mortality was assessed by the area under the curve (AUC) of the receiver operating curve (ROC).

RESULTS

A total of 2997 patients were considered in the study, with a median of 69 years (IQR 54-81) and 41.4% of women. The median pLA value was 2.7 mmol/L (1.9-3.8) in survivors and 5.7 mmol/L (4.4-7.6) in nonsurvivors. The global discrimination level of pLA reached an AUC of 0.867, being 1.9 mmol/L and 4 mmol/L the cut-off point for low and high mortality. The discrimination value of pLA was not affected by sex, age or pathology.

CONCLUSIONS

Our results highlight the clinical importance of prehospital pLA to determine the in-hospital risk of mortality. The incorporation of pLA into the EMS protocols could improve the early identification of risky patients, leading to a better care of such patients.

Clinical Utility of Delta Lactate for Predicting Early In-Hospital Mortality in Adult Patients: A Prospective, Multicentric, Cohort Study

One of the challenges in the emergency department (ED) is the early identification of patients with a higher risk of clinical deterioration. The objective is to evaluate the prognostic capacity of ΔLA (correlation between prehospital lactate (pLA) and hospital lactate (hLA)) with respect to in-hospital two day mortality. We conducted a pragmatic, multicentric, prospective and blinded-endpoint study in adults who consecutively attended and were transported in advanced life support with high priority from the scene to the ED. The corresponding area under the receiver operating characteristics curve (AUROC) was obtained for each of the outcomes. In total, 1341 cases met the inclusion criteria. The median age was 71 years (interquartile range: 54–83 years), with 38.9% (521 cases) females. The total 2 day mortality included 106 patients (7.9%). The prognostic precision for the 2 day mortality of pLA and hLA was good, with an AUROC of 0.800 (95% CI: 0.74–0.85; p < 0.001) and 0.819 (95% CI: 0.76–0.86; p < 0.001), respectively. Of all patients, 31.5% (422 cases) had an ΔLA with a decrease of <10%, of which a total of 66 patients (15.6%) died. A lactate clearance ≥ 10% is associated with a lower risk of death in the ED, and this value could potentially be used as a guide to determine if a severely injured patient is improving in response to the established treatment.