Identifying high-risk undifferentiated emergency department patients with hyperlactatemia: Predictors of 30-day in-hospital mortality.

BACKGROUND: Hyperlactatemia has been recognized as a significant prognostic indicator in critically ill patients. Nonetheless, there remains a gap in understanding the specific risk factors contributing to increased mortality among undifferentiated emergency department (ED) patients presenting with elevated lactate levels. OBJECTIVES: The objective of the study is to investigate potential risk factors for 30-day in-hospital mortality in ED patients with hyperlactatemia. METHODS: All nontraumatic adult presentations to the ED who had a lactate level of ≥2.5 mmol/L were included. Comorbidities, vital signs, lactate levels, lactate clearance, lactate normalization, and final diagnosis were compared with 30-day in-hospital mortality. RESULTS: A 30-day in-hospital mortality rate of 10.4% was observed in 979 patients. The mortality rate was higher in hypotensive patients (odds ratio [OR] 4.973), in nursing home patients (OR 5.689), and bedridden patients (OR 3.879). The area under the curve for the second lactate level (0.804) was higher than the first lactate level (0.691), and lactate clearance (0.747) for in-hospital mortality. A second lactate level >3.15 mmol/l had a sensitivity of 81.3% in predicting in-hospital mortality. The OR for mortality was 6.679 in patients without lactate normalization. A higher mortality rate was observed in patients with acute renal failure (OR 4.305), septic shock (OR 4.110), and acute coronary syndrome (OR 2.303). CONCLUSIONS: A second lactate measurement more accurately predicts in-hospital mortality than lactate clearance and the first lactate level in ED patients. Nursing home patients, bed-ridden patients, hypotensive patients on initial ED presentation, patients without lactate normalization, and patients with a final diagnosis of acute renal failure, septic shock, and acute coronary syndrome had a higher mortality rate.

The 6-hour lactate clearance rate in predicting 30-day mortality in cardiogenic shock.

Background: Early evaluation of prognosis in cardiogenic shock (CS) is crucial for tailored treatment selection. Both lactate clearance and lactate levels are considered useful prognostic biomarkers in patients with CS. However, there is yet no literature comparing the 6-hour lactate clearance rate (Δ6Lac) with lactate levels measured at admission (L1) and after 6 h (L2) to predict 30-day mortality in CS. Methods: In this observational cohort study, 95 patients with CS were treated at Department of Intensive Care Unit, Yiwu Central Hospital between January 2020 and December 2022. Of these, 88 patients met the eligibility criteria. The lactate levels were measured after admission (L1) as the baseline lactate value, and were measured after 6 h (L2) following admission. The primary endpoint of the study was survival rate at 30 days. A receiver operating characteristic curve was used for data analysis. Univariate and multivariate Cox regression analyses were performed based on Δ6Lac. Kaplan-Meier (KM) survival curves were generated to compare the 30-day survival rates among L1, L2, and Δ6Lac. Results: The Δ6Lac model showed the highest area under the curve value (0.839), followed by the L2 (0.805) and L1 (0.668) models. The Δ6Lac model showed a sensitivity of 84.2% and specificity of 75.4%. The L1 and L2 models had sensitivities of 57.9% each and specificities of 89.9% and 98.6%, respectively. The cut-off values for Δ6Lac, L1, and L2 were 18.2%, 6.7 mmol/L, and 6.1 mmol/L, respectively. Univariate Cox regression analysis revealed a significant association between Δ6Lac and 30-day mortality. After adjusting for five models in multivariate Cox regression, Δ6Lac remained a significant risk factor for 30-day mortality in patients with CS. In our fifth multivariate Cox regression model, Δ6Lac remained a risk factor associated with 30-day mortality (hazard ratio [HR]=5.14, 95% confidence interval [CI]: 1.48 to 17.89, P=0.010) as well as L2 (HR=8.42, 95% CI: 1.26 to 56.22, P=0.028). The KM survival curve analysis revealed that L1 >6.7 mmol/L (HR=8.08, 95% CI: 3.23 to 20.20, P <0.001), L2 >6.1 mmol/L (HR=25.97, 95% CI: 9.76 to 69.15, P <0.001), and Δ6Lac ≤18.2% (HR=8.92, 95% CI: 2.95 to 26.95, P <0.001) were associated with a higher risk of 30-day mortality. Conclusions: Δ6Lac is a better predictor for 30-day mortality in CS than lactate levels at admission. It has a predictive value equivalent to that of lactate level at 6 h after admission, making it an important surrogate indicator for evaluating the suitability as well as poor prognosis after CS treatment. We found that a cut-off value of 18.2% for Δ6Lac provided the most accurate assessment of early prognosis in CS.

Preoperative risk factors for 90-day postoperative mortality outcome in patients with non-occlusive mesenteric ischemia.

PURPOSE: The mortality rate for non-occlusive mesenteric ischemia remains high even after patients survive the acute postoperative period with tremendous treatment efforts, including emergency surgery, which is challenging. The aim of this study was to explore the preoperative risk factors for 90-day postoperative mortality in patients with non-occlusive mesenteric ischemia. METHODS: This single-center, retrospective cohort study included patients diagnosed with non-occlusive mesenteric ischemia who underwent emergency surgery between August 2014 and January 2023. All patients were divided into survival-to-discharge and mortality outcome groups at the 90-day postoperative follow-up. Preoperative factors, including comorbidities, preoperative status of vital signs and consciousness, blood gas analysis, blood test results, and computed tomography, were compared between the two groups. RESULTS: Twenty patients were eligible, and 90-day mortality was observed in 10 patients (50%). The mortality outcome group had significantly lower HCO3- (20.9 vs. 14.6, p = 0.006) and higher lactate (4.4 vs. 9.4, p = 0.023) levels than did the survival outcome group. The median postoperative time to death was 19 [2-69] days, and five patients (50%) died after postoperative day 30, mainly because hemodialysis was discontinued because of hemodynamic instability in patients requiring hemodialysis. CONCLUSION: Low preoperative HCO3- and high lactate levels may be preoperative risk factors for 90-day postoperative mortality in patients with non-occlusive mesenteric ischemia. However, patients on hemodialysis die from discontinuing hemodialysis even after surviving the acute postoperative phase. Therefore, indications for emergency surgery in patients with risk factors for postoperative mortality should be carefully determined.

Association of Postoperative Serum Lactate Levels with Acute Kidney Injury in Mexican Patients Undergoing Cardiac Surgery.

Acute kidney injury (AKI) is a highly prevalent and a critical complication of cardiac surgery (CS). Serum lactate (sLac) levels have consistently shown an association with morbimortality after CS. We performed a cross-sectional study including 264 adult patients that had a cardiac surgery between January and December 2020. Logistic regression analysis was performed to determine factors associated with AKI development. We measured the postoperative levels of sLac for all participants immediately after CS (T0) and at 4 h (T4) after the surgical intervention. A linear regression model was used to identify the factors influencing both sLac metrics. We identified four risk predictors of AKI; one was preoperative (atrial fibrillation), one intraoperative (cardiopulmonary bypass time), and two were postoperative (length of hospital stay and postoperative sLac). T0 and T4 sLac levels were higher among CS-AKI patients than in Non-CS-AKI patients. Postoperative sLac levels were significant independent predictors of CSA-AKI, and sLac levels are influenced by length of hospital stay, the number of transfused packed red blood cells, and the use of furosemide in CS-AKI patients. These findings may facilitate the earlier identification of patients susceptible to AKI after CS.

Venoarterial Partial Pressure of Carbon Dioxide Difference: Let's Trend It!

How to cite this article: Ravisankar NR. Venoarterial Partial Pressure of Carbon Dioxide Difference: Let's Trend It! Indian J Crit Care Med 2024;28(4):323-325.

Sepsis-Induced Myocardial Dysfunction in Pediatric Septic Shock: Prevalence, Predictors, and Outcome-A Prospective Observational Study.

There is a paucity of literature on the prevalence, predictors, prognostic markers, and outcomes of sepsis-induced myocardial dysfunction (SMD) in pediatric septic shock. The objectives of our study were to estimate the prevalence of SMD in pediatric septic shock by point-of-care functional echocardiography (POCFE) and to study the association of SMD with severity of illness, organ dysfunctions, and outcomes. This prospective, observational study was conducted over a period of 1 year (from July 2018 to July 2019) in a 12-bed, tertiary pediatric intensive care unit (PICU) of an academic and referral hospital in South India. Children presenting with septic shock were enrolled in the study. POCFE was done within 6 hours of PICU admission and patients were categorized as having SMD based on POCFE findings. The prevalence of SMD (left ventricle ± right ventricle) was 32% (32/100). More than half of the children (54.5%) died in SMD group, whereas only 7.5% died in non-SMD group ( p < 0.001). SMD was associated with higher organ dysfunctions, worse patient outcomes, and was found to be an independent predictor of mortality. The median lactate levels were higher in SMD group (3.15 [2.7, 5] vs. 2 [1.3, 2.7], p < 0.001) as compared with non-SMD group. We observed significantly lower median lactate clearance at 6 hours in SMD than non-SMD (30.0% [-14.44, 44.22] vs. 59.8% [45.83, 71.43], p < 0.001). Lactate levels at 6 hours with a threshold of 2.4 mmol/L was a good predictor of SMD with sensitivity and specificity of 73 and 80%, respectively. SMD is not an uncommon entity in children with septic shock. SMD was associated with worse patient outcomes, organ dysfunction, and mortality. Serum lactate trends may predict SMD and can be used as prognosticate markers as well.

Prognostic accuracy of mean arterial pressure and serum lactate level in patients with acute myocardial infarction.

BACKGROUND: Mean arterial pressure (MAP) can be used to evaluate macro-circulatory perfusion while serum lactate concentration is a marker of tissue perfusion. It is important to note that the primary objective of initial medical interventions is to restore microcirculatory perfusion rather than focusing solely on macro-hemodynamics. AIMS: We aimed to investigate the prognostic value of the combination of MAP and serum lactate levels measured on admission to the hospital in relation to patients' 30-day survival rate in patients with acute myocardial infarction (MI). METHODS: Data from 532 consecutive patients with acute MI treated with percutaneous coronary intervention were analyzed. The study endpoint was 30-day all-cause mortality. RESULTS: We found that both MAP and lactate levels were relevant predictors of the 30-day mortality in multivariable Cox regression analysis (HR, 0.83; 95% CI, 0.71-0.97; P = 0.02 and HR, 1.16; 95% CI, 1.06-1.16; P = 0.01, respectively). There was a significant increase in the prognostic performance in relation to 30-day mortality for the combination of both MAP and lactate levels in comparison to MAP alone (P = 0.03 for comparison between areas under the curve). Conversely, the combination of MAP and lactates did not add a significant prognostic value in comparison to lactates alone (P = 0.53 for comparison between areas under the curve). CONCLUSIONS: In patients with acute MI, serum lactate level seems to have a higher prognostic value in comparison to MAP. Our data suggest that on initial assessment of patients with acute myocardial infarction, we should move toward a tissue perfusion-based approach instead of focusing on a blood pressure-oriented strategy alone.

The significance of initial lactate levels in emergency department presentations of abdominal wall hernia.

INTRODUCTION: Abdominal wall hernias are a frequent cause of abdominal pain-related emergency department visits. Our study aimed to establish the connection between lactate levels and patient outcomes in those with abdominal pain due to abdominal wall hernias. MATERIALS AND METHODS: Our research followed a retrospective, observational, and descriptive approach and two center. We included patients who visited the emergency department for abdominal pain and were confirmed to have abdominal wall hernias through ultrasound. RESULTS: We enrolled 493 patients meeting the criteria. Median age was 65 years, with 54% (n = 266) being male. Regarding outcomes, 40.5% (n = 200) were hospitalized, 27.7% (n = 137) underwent surgery, and 7.9% (n = 39) underwent bowel resection. Mortality rate during hernia-related hospital admission was 0.6% (n = 3). For hospitalized patients, there were significant differences in white blood cell count, neutrophil count and percentage, platelet count, lymphocyte count, and percentage (p < 0.05). Patients undergoing resection showed significant differences in neutrophil count, neutrophil percentage, lymphocyte count, and lymphocyte percentage (p < 0.05). Lactate levels were statistically significant in all patient groups requiring hospitalization, surgery, and resection (p < 0.05). Sensitivity and specificity of lactate test results indicated in patients undergoing bowel resection, lactate values ≥1.96 mmol/L had a specificity of 64%, sensitivity of 71%, and a negative predictive value of 96% (p < 0.05). CONCLUSION: Low lactate levels in patients presenting to the emergency department with abdominal pain caused by abdominal wall hernias have a high negative predictive value for excluding strangulation and the need for bowel resection. Therefore, we recommend the use of lactate as an additional diagnostic tool in emergency department presentations related to abdominal wall hernias.

Effect of a Mediterranean-style diet on the exercise performance and lactate elimination on adolescent athletes.

BACKGROUND/OBJECTIVES: Mediterranean diet is an environmentally friendly and healthy diet model. The diet offers many vegetables, fruits, nuts, and olive oil to consumers. In addition, it provides moderate amounts of fish and chicken, smaller quantities of dairy products, red meat, and processed meat. The Mediterranean diet has a high anti-inflammatory and antioxidant content, and it causes many physiological changes that can provide a physical performance advantage. This study examined the effects of a 15-day menu, which was planned using foods with a low acid load within the Mediterranean diet rules, on the exercise performance, lactate elimination, anthropometric measurements, and body composition. SUBJECTS/METHODS: Fifteen professional male athletes between the ages of 13 and 18, who were engaged in ski running, were included in the experimental study. Dietary intervention was applied for 15 days. The athlete performances were evaluated by applying the vertical jump test, hand grip strength, 20 meters shuttle run test, and Borg fatigue scale. After the shuttle run test (every 3 min for 30 min), blood was drawn from the finger, and the lactate elimination time was calculated. Performance and lactate measurements, body analysis, and anthropometric measurements were taken before and after dietary intervention. RESULTS: The vertical jump height and hand grip strength increased after the intervention (P < 0.05). The test duration, total distance, the number of shuttles, and maximum oxygen consumption parameters of the shuttle run test increased (P < 0.05). After the intervention, the athletes' perceived fatigue scores decreased in several stages of the shuttle run test (P < 0.05). The lactate elimination time and athlete's body composition were similar in repeated measurements (P > 0.05). In the last measurements, the upper middle arm circumference decreased while the height of the athletes increased (P < 0.05). CONCLUSIONS: These results show that the Mediterranean diet is a safe and feasible dietary approach for aerobic performance and strength increase.

Factors Predicting Early Major Adverse Events in the Intensive Care Unit After Successful Cardiac Surgery for Congenital Heart Disease in Full-Term Neonates.

OBJECTIVE: In this study, we aimed to evaluate the factors affecting major adverse event (MAE) development after full-term neonatal cardiac surgery. METHODS: This study was conducted retrospectively on newborns who underwent congenital heart surgery between June 1, 2020, and June 1, 2022. MAE was defined as the presence of at least one of the following: cardiac arrest, unplanned reoperation, emergency chest opening, admission to the advanced life support system, and death. The role of blood lactate level, vasoactive inotropic score (VIS), and cerebral near-infrared spectroscopy (NIRS) changes in predicting MAE was investigated. RESULTS: A total of 240 patients (50% male) were operated during the study period. The median age of patients was seven days (interquartile range 3-10 days). MAE was detected in 19.5% of the cases. Peak blood lactate levels >7 mmol/liter (area under the curve [AUC] 0.72, 95% confidence interval [CI] [0.62-0.82], P<0.001, sensitivity 76%, specificity 82%, positive predictive value [PPV] 88%) was an independent risk factor for MAE (odds ratio [OR] 2.7 [95% CI 1.3-6]). More than 30% change in NIRS value during the operative period (AUC 0.84, 95% CI [0.80-0.88], P<0.001, sensitivity 65%, specificity 85%, PPV 90%) was a strong predictor of MAE. VIS > 10 was an independent risk factor (AUC 0.75, 95% CI [0.70-0.84], P<0.001, sensitivity 86%, specificity 80%, PPV 84%) and strongly predicted MAE (OR 1.4 [95% CI 0.9-5]). CONCLUSION: Cerebral NIRS changes > 30%, high blood lactate levels, and VIS score within the 48 hours may help to predict the development of MAE in the postoperative period.

Diagnostic value of the serum lactate level as a predictor of bacteremia in patients with acute cholangitis.

BACKGROUND: Patients with acute cholangitis (AC) have increased mortality when associated with bacteremia. This study aimed to evaluate the predictive ability of serum lactate (Lac) for positive bacteremia in patients with acute cholangitis. METHODS: In this single-center, retrospective study, 138 consecutive patients with AC were analyzed. Their blood samples were collected and Lac was measured. RESULTS: A total of 50 patients showed grade I, 50 showed grade II, and 38 showed grade III severity according to the Tokyo Guidelines 2018. Positive bacteremia was observed in 71 patients, of which 15 showed grade I, 25 showed grade II, and 31 showed grade III severity. Logistic regression analysis showed that Lac was a significant predictor of bacteremia. The area under the curve of Lac and procalcitonin (PCT) for bacteremia were 0.737 and 0.780, respectively. The optimal cutoff values for bacteremia were 17 mg/dL and 2.8 ng/mL, with sensitivity of 69.0% and 68.3%, respectively. Sensitivity of Lac and PCT for bacteremia in grade I was 58.3% and 25.0%, respectively. Three patients died from AC, all of whom were positive for bacteremia and hyperlactatemia. CONCLUSION: Lac is useful for predicting bacteremia in patients with AC.

The role of stress hyperglycemia and hyperlactatemia in non-diabetic patients with myocardial infarction treated with percutaneous coronary intervention.

BACKGROUND: Stress hyperglycemia and lactates have been used separately as markers of a severe clinical condition and poor outcomes in patients with myocardial infarction (MI). However, the interplay between glucose and lactate metabolism in patients with MI have not been sufficiently studied. The aim in the present study was to examine the relationship of glycemia on admission (AG) and lactate levels and their impact on the outcome in non-diabetic MI patients treated with percutaneous coronary intervention (PCI). METHODS: A total of 405 consecutive, non-diabetic, MI patients were enrolled in this retrospective, observational, single-center study. Clinical characteristic including glucose and lactate levels on admission and at 30-day mortality were assessed. RESULTS: Patients with stress hyperglycemia (AG ≥ 7.8 mmol/L, n = 103) had higher GRACE score (median [interquartile range]: 143.4 (115.4-178.9) vs. 129.4 (105.7-154.5), p = 0.002) than normoglycemic patients (AG level < 7.8 mmol/L, n = 302). A positive correlation of AG with lactate level (R = 0.520, p < 0.001) was observed. The coexistence of both hyperglycemia and hyperlactatemia (lactate level ≥ 2.0 mmol/L) was associated with lower survival rate in the Kaplan-Meier estimates (p < 0.001). In multivariable analysis both hyperglycemia and hyperlactatemia were related to a higher risk of death at 30-day follow-up (hazard ratio [HR] 3.21, 95%, confidence interval [CI] 1.04-9.93; p = 0.043 and HR 7.08; 95% CI 1.44-34.93; p = 0.016, respectively) CONCLUSIONS: There is a relationship between hyperglycemia and hyperlactatemia in non-diabetic MI patients treated with PCI. The coexistence of both hyperglycemia and hyperlactatemia is associated with lower survival rate and are independent predictors of 30-day mortality in MI patients and these markers should be evaluated simultaneously.

Comparison between Capillary and Serum Lactate Levels in Predicting Short-Term Mortality of Septic Patients at the Emergency Department.

Sepsis is a time-dependent and life-threating condition related to macro- and micro-circulatory impairment leading to anaerobic metabolism and lactate increase. We assessed the prognostic accuracy of capillary lactates (CLs) vs. serum ones (SLs) on 48-h and 7-day mortality in patients with suspected sepsis. This observational, prospective, single-centre study was conducted between October 2021 and May 2022. Inclusion criteria were: (i) suspect of infection; (ii) qSOFA ≥ 2; (iii) age ≥ 18 years; (iv) signed informed consent. CLs were assessed with LactateProTM2®. 203 patients were included: 19 (9.3%) died within 48 h from admission to the Emergency Department, while 28 (13.8%) within 7 days. Patients deceased within 48 h (vs. survived) had higher CLs (19.3 vs. 5 mmol/L, p < 0.001) and SLs (6.5 vs. 1.1 mmol/L, p = 0.001). The best CLs predictive cut-off for 48-h mortality was 16.8 mmol/L (72.22% sensitivity, 94.02% specificity). Patients within 7 days had higher CLs (11.5 vs. 5 mmol/L, p = 0.020) than SLs (2.75 vs. 1.1 mmol/L, p < 0.001). The multivariate analysis confirmed CLs and SLs as independent predictors of 48-h and 7-day mortality. CLs can be a reliable tool for their inexpensiveness, rapidity and reliability in identifying septic patients at high risk of short-term mortality.

Role of cerebrospinal fluid lactate in diagnosing meningitis in critically ill patients.

BACKGROUND: Meningitis is a life-threatening clinical condition associated with high mortality and morbidity. Early diagnosis and specific treatment may improve outcomes. Lack of specific clinical signs or tests make the diagnosis challenging. AIM: To assess the efficacy of cerebrospinal fluid (CSF) lactate in diagnosing meningitis in critically ill patients. METHODS: A prospective, observational cohort study was carried out in a neuro-medical intensive care unit (ICU) over a 22 mo period. Adult patients, with suspected meningitis admitted in ICU, were serially recruited. Patients who refused consent, those with peripheral sensorineural deficit, or with any contraindication to lumber puncture were excluded. CSF cytology, bio-chemistry, lactates, culture and polymerase chain reaction based meningo-encephalitis panel were evaluated. Patients were divided in two groups based on clinical diagnosis of meningitis. The efficacy of CSF lactate in diagnosing meningitis was evaluated and compared with other tests. RESULTS: Seventy-one patients were included and 23 were diagnosed with meningitis. The mean values of CSF total leucocyte count (TLC), proteins and lactates were significantly higher in meningitis group. There was a significant correlation of CSF lactate levels with CSF cultures and meningo-encephalitis panel. CSF lactate (> 2.72 mmol/L) showed good accuracy in diagnosing meningitis with an area under the curve of 0.81 (95% confidence interval: 0.69-0.93), sensitivity of 82.6%, and specificity 72.9%. These values were comparable to those of CSF TLC and protein. Twelve patients with bacterial meningitis had significantly higher CSF lactate (8.9 ± 4.7 mmol/L) than those with non-bacterial meningitis (4.2 ± 3.8 mmol/L), P = 0.006. CONCLUSION: CSF lactate may be used to aid in our diagnosis of meningitis in ICU patients. CSF lactate (> 2.72 mmol/L) showed good accuracy, sensitivity, and specificity in diagnosing meningitis and may also help to differentiate between bacterial and non-bacterial meningitis.

Acute mesenteric ischemia: which predictive factors of delayed diagnosis at emergency unit?

PURPOSE: Acute mesenteric ischemia (AMI) is frequently diagnosed late, leading to a poor prognosis. Our aims were to identify predictive factors of delayed diagnosis and to analyze the outcomes of patients with AMI admitted in emergency units. METHODS: All the patients with AMI (2015-2020), in two Emergency units, were retrospectively included. Two groups were defined according to the time of diagnosis between the arrival at emergency unit and the CT scan: ≤ 6 h (early), > 6 h (delayed). RESULTS: 119 patients (mean age = 71 ± 7 years) were included. The patients with a delayed diagnosis (n = 33, 28%) were significantly associated with atypical presentation, including lower rates of abdominal pain (73 vs 89%, p = 0.003), abdominal tenderness (33 vs 43%, p = 0.03), and plasma lactate (4 ± 2 vs 6 ± 7 mmol/l, p = 0.03) when compared with early diagnosis. After multivariate analysis, the absence of abdominal pain was the only independent predictive factor of delayed diagnosis (Odd Ratio = 0.17; 95% CI = 0.03-0.88, p = 0.03). Patients with delayed diagnosis tended to be associated to lower rates of revascularization (9 vs 17%, p = 0.4), higher rates of major surgical morbidity (90 vs 57%, p = 0.1), longer length of stay (16 ± 23 vs 13 ± 15 days, p = 0.4) and, at the end of follow-up, higher rate of short small bowel syndrome (18 vs 7%, p = 0.095). CONCLUSION: AMI is a challenge for emergency physicians. History of patient, physical exam, biological data are not sufficient to diagnose AMI. New biomarkers, and awareness of emergency physicians should improve and accelerate the diagnosis of AMI.

Factors Predicting Early Major Adverse Events in the Intensive Care Unit After Successful Cardiac Surgery for Congenital Heart Disease in Full-Term Neonates

ABSTRACT Objective: In this study, we aimed to evaluate the factors affecting major adverse event (MAE) development after full-term neonatal cardiac surgery. Methods: This study was conducted retrospectively on newborns who underwent congenital heart surgery between June 1, 2020, and June 1, 2022. MAE was defined as the presence of at least one of the following: cardiac arrest, unplanned reoperation, emergency chest opening, admission to the advanced life support system, and death. The role of blood lactate level, vasoactive inotropic score (VIS), and cerebral near-infrared spectroscopy (NIRS) changes in predicting MAE was investigated. Results: A total of 240 patients (50% male) were operated during the study period. The median age of patients was seven days (interquartile range 3-10 days). MAE was detected in 19.5% of the cases. Peak blood lactate levels >7 mmol/liter (area under the curve [AUC] 0.72, 95% confidence interval [CI] [0.62-0.82], P<0.001, sensitivity 76%, specificity 82%, positive predictive value [PPV] 88%) was an independent risk factor for MAE (odds ratio [OR] 2.7 [95% CI 1.3-6]). More than 30% change in NIRS value during the operative period (AUC 0.84, 95% CI [0.80-0.88], P<0.001, sensitivity 65%, specificity 85%, PPV 90%) was a strong predictor of MAE. VIS > 10 was an independent risk factor (AUC 0.75, 95% CI [0.70-0.84], P<0.001, sensitivity 86%, specificity 80%, PPV 84%) and strongly predicted MAE (OR 1.4 [95% CI 0.9-5]). Conclusion: Cerebral NIRS changes > 30%, high blood lactate levels, and VIS score within the 48 hours may help to predict the development of MAE in the postoperative period.

Lactate Production can Function to Increase Human Epithelial Cell Iron Concentration.

Introduction: Under conditions of limited iron availability, plants and microbes have evolved mechanisms to acquire iron. For example, metal deficiency stimulates reprogramming of carbon metabolism, increasing activity of enzymes involved in the Krebs cycle and the glycolytic pathway. Resultant carboxylates/hydroxycarboxylates then function as ligands to complex iron and facilitate solubilization and uptake, reversing the metal deficiency. Similarly, human intestinal epithelial cells may produce lactate, a hydroxycarboxylate, during absolute and functional iron deficiency to import metal to reverse limited availability. Methods: Here we investigate (1) if lactate can increase cell metal import of epithelial cells in vitro, (2) if lactate dehydrogenase (LDH) activity in and lactate production by epithelial cells correspond to metal availability, and (3) if blood concentrations of LDH in a human cohort correlate with indices of iron homeostasis. Results: Results show that exposures of human epithelial cells, Caco-2, to both sodium lactate and ferric ammonium citrate (FAC) increase metal import relative to FAC alone. Similarly, fumaric, isocitric, malic, and succinic acid coincubation with FAC increase iron import relative to FAC alone. Increased iron import following exposures to sodium lactate and FAC elevated both ferritin and metal associated with mitochondria. LDH did not change after exposure to deferoxamine but decreased with 24 h exposure to FAC. Lactate levels revealed decreased levels with FAC incubation. Review of the National Health and Nutrition Examination Survey demonstrated significant negative relationships between LDH concentrations and serum iron in human cohorts. Conclusions: Therefore, we conclude that iron import in human epithelial cells can involve lactate, LDH activity can reflect the availability of this metal, and blood LDH concentrations can correlate with indices of iron homeostasis.

[Optimal oxygen administration-new evidence from treating COVID-19?] / Optimale Sauerstoffversorgung ­ neue Erkenntnisse aus der COVID-19-Therapie?

Oxygen is essential for energy production and thus for the survival of human cells. If oxygen delivery is disrupted due to illness, injury or changes in environmental factors, the human body is to a certain extent able to activate compensatory mechanisms to ensure adequate delivery of oxygen for the function and integrity of the cells and organ systems. If these compensatory mechanisms are exhausted or overloaded, there is a risk of functional failure of cells and organ systems. In clinical practice, it is often difficult to decide whether the body's own compensation mechanisms are still sufficient or whether more invasive therapy options and their side effects should be used to prevent organ damage. The aim of this review is to reiterate the basic physiological mechanisms of oxygen delivery to cells, to show how insufficient oxygen can be detected, and to highlight the current state of studies and guidelines on target oxygen levels. Although the coronavirus disease 2019 (COVID-19) pandemic has brought recent attention to the pathophysiology and therapeutic strategies of oxygenation disorders, little new knowledge regarding oxygen targets has emerged from this pandemic. Thus, the previously recommended oxygen target values remain unchanged.

Effect of Wearing Surgical Face Masks During Exercise: Does Intensity Matter?

Face masks are widely recommended as means of controlling the coronavirus disease outbreak. This study aimed to examine the physiological and perceptual responses of wearing surgical face masks while exercising at different intensities. Thirteen healthy young adults (mean age, 21.9 ± 1.4 years) conducted randomized crossover trials with or without a surgical face mask. In each trial, participants completed an incremental treadmill protocol, with three 6-min stages (light, moderate, and vigorous at 25, 50, and 75% maximal oxygen uptake, respectively). Physiological outcomes (heart rate, blood lactate, and oxygen saturation level), perceived exertion and discomfort feeling were assessed. No significant differences were observed in physiological outcomes with or without masks at different exercise intensities (p > 0.05). However, the rating of perceived exertion (RPE) was significantly higher when exercising vigorously (mask: 15.5 ± 1.5 vs. no-mask: 14.2 ± 2.1, p < 0.05). Participants wearing masks reported marked discomfort, such as feeling hot, humid, and breathing resistance. Although face mask-wearing during exercise may not have detrimental effects on major physiological parameters, it can increase perceived exertion level and discomfort when the exercise intensity exceeds a certain threshold. Therefore, healthcare professionals should cautiously evaluate each person's ability to exercise while wearing a mask and tailor their prescription accordingly.

Role of TRPV4 Channel in Human White Adipocytes Metabolic Activity.

BACKGROUND: Intracellular calcium (Ca2+) homeostasis plays an essential role in adipocyte metabolism and its alteration is associated with obesity and related disorders. Transient receptor potential vanilloid 4 (TRPV4) channels are an important Ca2+ pathway in adipocytes and their activity is regulated by metabolic mediators such as insulin. In this study, we evaluated the role of TRPV4 channels in metabolic activity and adipokine secretion in human white adipocytes. METHODS: Human white adipocytes were freshly cultured and the effects of the activation and inhibition of TRPV4 channels on lipolysis, glucose uptake, lactate production, and leptin and adiponectin secretion were evaluated. RESULTS: Under basal and isoproterenol-stimulated conditions, TRPV4 activation by GSK1016709A decreased lipolysis whereas HC067047, an antagonist, increased lipolysis. The activation of TRPV4 resulted in increased glucose uptake and lactate production under both basal conditions and insulin-stimulated conditions; in contrast HC067047 decreased both parameters. Leptin production was increased, and adiponectin production was diminished by TRPV4 activation and its inhibition had the opposite effect. CONCLUSION: Our results suggested that TRPV4 channels are metabolic mediators involved in proadipogenic processes and glucose metabolism in adipocyte biology. TRPV4 channels could be a potential pharmacological target to treat metabolic disorders.