Time-weighted lactate as a predictor of adverse outcome in acute heart failure.

AIMS: The role of dynamic changes in lactate concentrations on prognosis in acute heart failure has been poorly investigated. The aim of this study was to explore the predictive value of 24 h time-weighted lactate (LACTW ) in patients with acute heart failure. METHODS AND RESULTS: Ninety-six consecutive acute heart failure patients presenting to the Emergency Department of San Paolo Hospital, Naples, Italy, were prospectively enrolled. Arterial blood lactate was measured at admission and during the following 24 h at random time intervals. LACTW was obtained by the sum of the average lactate values among consecutive time points multiplied by the intervals between consecutive time points and dividing the sum by the total time (24 h). The outcome was a composite of need of admission to the intensive care unit, hospitalization duration >7 days, or intra-hospital death. Admission lactate, maximum measured lactate, and LACTW were collected. Univariate and multivariate Cox regression analysis was applied to determine the hazard ratio (HR) of developing the outcome. Forty-three patients experienced the pre-specified outcome. In sex-adjusted and age-adjusted multivariable analysis, LACTW predicted the outcome occurrence (HR: 1.51, 95% confidence interval: 1.24, 1.84, P < 0.001). Risk stratification analysis based on LACTW tertiles demonstrated a gradual increase in risk of developing the outcome (HR: 17.32, 95% confidence interval: 2.30, 130.23, P = 0.006) for the highest LACTW tertile. CONCLUSIONS: In acute heart failure patients, 24 h LACTW had a significant independent predictive value for adverse intra-hospital outcome. LACTW could be a useful index at identifying high-risk patients who may require a more aggressive treatment during hospitalization.

Lactate Arterial-Central Venous Gradient among COVID-19 Patients in ICU: A Potential Tool in the Clinical Practice.

OBJECTIVE: In physiological conditions, arterial blood lactate concentration is equal to or lower than central venous blood lactate concentration. A reversal in this rate (i.e., higher lactate concentration in central venous blood), which could reflect a derangement in the mitochondrial metabolism of lung cells induced by inflammation, has been previously reported in patients with ARDS but has been never explored in COVID-19 patients. The aim of this study was to explore if the COVID-19-induced lung cell damage was mirrored by an arterial lactatemia higher than the central venous one; then if the administration of anti-inflammatory therapy (i.e., canakinumab 300 mg subcutaneous) could normalize such abnormal lactate a-cv difference. METHODS: A prospective cohort study was conducted, started on March 25, 2020, for a duration of 10 days, enrolling 21 patients affected by severe COVID-19 pneumonia undergoing mechanical ventilation consecutively admitted to the ICU of the Rimini Hospital, Italy. Arterial and central venous blood samples were contemporarily collected to calculate the difference between arterial and central venous lactate (Delta a-cv lactate) concentrations within 24 h from tracheal intubation (T 0) and 24 hours after canakinumab administration (T 1). RESULTS: At T 0, 19 of 21 (90.5%) patients showed a pathologic Delta a-cv lactate (median 0.15 mmol/L; IQR 0.07-0.25). In the 13 patients undergoing canakinumab administration, at T 1, Delta a-cv lactate decreased in 92.3% of cases, the decrease being statistically significant (T 0: median 0.24, IQR 0.09-0.31 mmol/L; T 1: median -0.01, IQR -0.08-0.04 mmol/L; p=0.002). CONCLUSION: A reversed Delta a-cv lactate might be interpreted as one of the effects of COVID-19-related cytokine storm, which could reflect a derangement in the mitochondrial metabolism of lung cells induced by severe inflammation or other uncoupling mediators. In addition, Delta a-cv lactate decrease might also reflect the anti-inflammatory activity of canakinumab. Our preliminary findings need to be confirmed by larger outcome studies.

Lactate determination in pleural and abdominal effusions: a quick diagnostic marker of exudate-a pilot study.

Pleural or abdominal effusions are frequent findings in ICU and Internal Medicine patients. Diagnostic gold standard to distinguish between transudate and exudate is represented by "Light's Criteria," but, unfortunately, the chemical-physical examination for their calculation is not a rapid test. Pursuing an acid-base assessment of the fluid by a blood-gas analyzer, an increase of lactate beyond the normal serum range is reported in the exudative effusions. The advantages of this test are that it is a very fast bed-side test, executable directly by the physician. The aim of this study is to evaluate whether the increase in lactate in pleural and abdominal effusions might be used as a criterion for the differential diagnosis of the nature of the fluid. Sixty-nine patients with pleural or abdominal effusions and clinical indication for thoracentesis or paracentesis were enrolled. Acid-base assessment with lactate, total protein, and LDH dosage on the serum, and acid-base assessment with lactate, total protein, and LDH dosage, cytology, and bacterial culture on the fluid were performed to each patient. Fluid-blood lactate difference (ΔLacFB) and fluid-blood lactate ratio (LacFB ratio) were calculated. A statistical analysis was carried out for fluid lactate (LacF), ΔLacFB, and LacFB ratio, performing ROC curves to find the cut-off values with best sensitivity (Sn) and specificity (Sp) predicting an exudate diagnosis: LacF: cut-off value: 2.4 mmol/L; AU-ROC 0.854 95% CI 0.756-0.952; Sn 0.77; Sp 0.84. ΔLacFB: cut-off value: 0.95 mmol/L; Au-ROC 0.876 95% CI 0.785-0.966; Sn 0.80; Sp 0.92. LacFB ratio: cut-off value: 2 mmol/L; Au-ROC 0.730 95% CI 0.609-0.851; Sn 0.74; Sp 0.65. Lactate dosage by blood-gas analyzer on pleural and abdominal effusions seems to be a promising tool to predict a diagnosis of exudate.

Lung ultrasound for diagnosis of pneumonia in emergency department.

Lung ultrasound (LUS) in the emergency department (ED) has shown a significant role in the diagnostic workup of pulmonary edema, pneumothorax and pleural effusions. The aim of this study is to assess the reliability of LUS for the diagnosis of acute pneumonia compared to chest X-ray (CXR) study. The study was conducted from September 2013 to March 2015. 107 patients were admitted to the ED with a clinical appearance of pneumonia. All the patients underwent a CXR study, read by a radiologist, and an LUS, performed by a trained ED physician on duty. Among the 105 patients, 68 were given a final diagnosis of pneumonia. We found a sensitivity of 0.985 and a specificity of 0.649 for LUS, and a sensitivity of 0.735 and specificity of 0.595 for CXR. The positive predictive value for LUS was 0.838 against 0.7 for CXR. The negative predictive value of LUS was 0.960 versus 0.550 for CXR. This study has shown sensitivity, positive predictive value and negative predictive value of LUS compared to the CXR study for the diagnosis of acute pneumonia. These results suggest the use of bedside thoracic US first-line diagnostic tool in patients with suspected pneumonia.

[Central venous blood gas analysis]. / Emogasanalisi dal catetere venoso centrale: una finestra sulla perfusione.

The hemodialysis might interfere with patients hemodynamic, as the technique allows a sophisticated game with extra and intravascular fluids. As the cardiocirculatory response could sometimes be unpredictable, it is interesting to collect valuable information by reaching a deep understanding of the tissue metabolism which is mirrored by the blood gas analysis of variations in arterial and central venous blood samples. Particularly interesting are the time course variations of the central venous hemoglobin saturation (ScvO2), which are directly related to the patient with O2-demand as well as to the O2-Delivery (DO2). The ScvO2 is determined by four parameters (cardiac output, Hb concentration, arterial Hb saturation and O2 consumption): If the fluids subtraction during dialysis was about to determine an occult hypoperfusion, the ScvO2 reduction would be a timely warning sign to be considered. Moreover, while the normal veno-arterial PCO2 difference is 2-4 mmHg, whenever a mismatch between O2-demand and DO2arise, a larger v-aPCO2 difference should be observed.

Tetraparesis and failure of pacemaker capture induced by severe hyperkalemia: case report and systematic review of available literature.

BACKGROUND: In severe hyperkalemia, neurologic symptoms are described more rarely than cardiac manifestations. We report a clinical case; present a systematic review of available literature on secondary hyperkalemic paralysis (SHP); and also discuss pathogenesis, clinical effects, and therapeutic options. CASE REPORT: A 75-year-old woman presented to the emergency department complaining of tetraparesis. Her serum potassium level was 11.4 mEq/L. Electrocardiogram (ECG) showed a pacemaker (PMK)-induced rhythm, with loss of atrial capture and wide QRS complexes. After emergency treatment to restore cell membrane potential threshold and lower serum potassium, neurologic and ECG signs completely disappeared. An acute myocardial infarction subsequently occurred, possibly linked to tachycardia induced by salbutamol therapy. We reviewed 99 articles (119 patients). Mean serum potassium was 8.8 mEq/L. In most cases, ECG showed the presence of tall T waves; loss of PMK atrial capture was documented in 5 patients. In 94 patients, flaccid paralysis was described and in 25, severe muscular weakness; in 65 patients, these findings were associated with other symptoms. Concurrent renal failure was often documented. The most frequent treatments were dialysis and infusion of insulin and glucose. Eighty-seven percent of patients had complete resolution of symptoms. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Severe hyperkalemia is always a life-threatening medical emergency, as it can precipitate fatal dysrhythmias and paralysis. SHP should be considered in the differential diagnosis of neurologic signs and symptoms of uncertain etiology, especially in a subject with kidney failure or who is taking medications that may worsen renal function. The presence of a PMK does not necessarily impede hyperkalemic cardiac toxicity.

Immediate versus delayed integrated point-of-care-ultrasonography to manage acute dyspnea in the emergency department.

BACKGROUND: Dyspnea is one of the most frequent complaints in the Emergency Department. Thoracic ultrasound should help to differentiate cardiogenic from non-cardiogenic causes of dyspnea. We evaluated whether the diagnostic accuracy can be improved by adding a point-of-care-ultrasonography (POC-US) to routine exams and if an early use of this technique produces any advantage. METHODS: One hundred sixty-eight patients were enrolled and randomized in two groups: Group 1 received an immediate POC-US in addition to routine laboratory and instrumental tests; group 2 received an ultrasound scan within 1 h from the admission to the Emergency Department. The concordance between initial and final diagnosis and the percentage of wrong diagnosis in the two groups were evaluated. Mortality, days of hospitalization in Emergency Medicine department and transfers to other wards were compared. Sensitivity and specificity of the routine protocol and the one including ultrasonography for the diagnosis of the causes of dyspnea were also analyzed. RESULTS: Eighty-eight patients were randomized in group 1 and 80 in group 2. The concordance rate between initial and final diagnoses was significantly different (0.94 in group 1 vs. 0.22 in group 2, p < 0.005). The percentage of wrong initial diagnosis was 5% in group 1 and 50% in group 2 (p < 0.0001). CONCLUSIONS: Adding POC-US to routine exams improves the diagnostic accuracy of dyspnea and reduces errors in the Emergency Department.

Base excess, strong ion difference, and expected compensations: as simple as it is.

The main purpose of this article is to provide some practical insights into acid-base disorders interpretation, comparing the three most widespread diagnostic approaches. After a brief summary of the history of blood gas analysis and the shift from a purely chemical approach to more clinically useful applications, the pros and cons of the different methodologies are compared and discussed. Reviewing the most important publications in the field, the authors attempt to show that each diagnostic strategy is acceptable, although the one based on base-excess calculation perhaps seems too 'rough' to understand the mixed disorders, whereas the Stewart approach is attractive from a chemical point of view, but unsuitable for the emergency physician because of the cumbersome calculations needed. Finally, the anion gap and 'expected compensation' approach seems to be more comprehensive and feasible at the bedside.

End-tidal arterial CO2 partial pressure gradient in patients with severe hypercapnia undergoing noninvasive ventilation.

BACKGROUND: Patients with severe hypercapnia represent a particularly serious condition in an emergency department (ED), requiring immediate attention. Noninvasive ventilation (NIV) is an integral part of the treatment for acute respiratory failure. The present study aimed to validate the measurement of end-tidal CO2 (EtCO2) as a noninvasive technique to evaluate the effectiveness of NIV in acute hypercapnic respiratory failure. METHODS: Twenty consecutive patients admitted to the ED with severe dyspnea were enrolled in the study. NIV by means of bilevel positive airway pressure, was applied to the patients simultaneously with standard medical therapy and continued for 12 hours; the arterial blood gases and side-stream nasal/oral EtCO2 were measured at subsequent times: T0 (admission to the ED), T1h (after 1 hour), T6h (after 6 hours), and T12h (after 12 hours) during NIV treatment. RESULTS: The arterial CO2 partial pressure (PaCO2)-EtCO2 gradient decreased progressively, reaching at T6h and T12h values lower than baseline (P < 0.001), while arterial pH increased during the observation period (P < 0.001). A positive correlation was found between EtCO2 and PaCO2 values (r = 0.89, P < 0.001) at the end of the observation period. CONCLUSION: In our hypercapnic patients, the effectiveness of the NIV was evidenced by the progressive reduction of the PaCO2-EtCO2 gradient. The measurement of the CO2 gradient could be a reliable method in monitoring the effectiveness of NIV in acute hypercapnic respiratory failure in the ED.

Dyselectrolytemias and arrhythmias.

Critical care patients are submitted to multiple derangements of vital parameters. Even in patients with a normally performing heart, its electrical activity can be strongly influenced by dyselectrolytemias, acid-base imbalance and aggressive drug therapy. In this paper, the basic principles of the electrophysiologic properties of the heart are reviewed, and the impact of dyselectrolytemias on heart excitability are underlined. Some clinically relevant aspects are described in greater depth, with respect to life-threatening arrhythmias.

Two-hour lactate clearance predicts negative outcome in patients with cardiorespiratory insufficiency.

Objective. To evaluate 2-hour lactate clearance as a prognostic marker in acute cardiorespiratory insufficiency. Design. Prospective observational study. Setting. Emergency Department (ED) and 16-bed medical High Dependency Unit (HDU). Methods and Main Results. 95 consecutive admissions from the ED for acute cardiorespiratory insufficiency were prospectively enrolled. Arterial lactate concentration was assessed at ED arrival and 1, 2, 6, and 24 hours later. The predictive value of 2-hour lactate clearance was evaluated for negative outcomes defined as hospital mortality or need for endotracheal intubation versus positive outcomes defined as discharge or transfer to a general medical ward. Logistic regression and ROC curves found 2-hour lactate clearance >15% was a strong predictor of negative outcome (P < .0001) with a sensitivity of 86% (95%CI = 67%-95%) and a specificity of 91% (95%CI = 82%-96%), Positive predictive value was 80% (95%CI = 61%-92%), and negative predictive value was 92% (95%CI = 84%-98%). Conclusions. Systematic monitoring of lactate clearance at 2 hours can be used in to identify patients at high risk of negative outcome and perhaps to tailor more aggressive therapy. Equally important is that a 2-hour lactate clearance >15% is highly predictive of positive outcome and may reassure clinicians that the therapeutic approach is appropriate.

Inferior vena cava collapsibility to guide fluid removal in slow continuous ultrafiltration: a pilot study.

OBJECTIVE: To investigate whether ultrasound determination of the inferior vena cava diameter (IVCD) and its collapsibility index (IVCCI) could be used to optimize the fluid removal rate while avoiding hypotension during slow continuous ultrafiltration (SCUF). METHODS: Twenty-four consecutive patients [13 men and 11 women, mean age 72 +/- 5 years; New York Heart Association (NYHA) functional classes III-IV] with acute decompensated heart failure (ADHF) and diuretic resistance were admitted to our 16-bed medical ICU. Blood pressure (BP), heart rate (HR), respiratory rate (RR), blood samples for hematocrit, creatinine, sodium, potassium, and arterial BGA plus lactate were obtained at baseline and than every 2 h from the beginning of SCUF. IVCD, assessed by M-mode subcostal echocardiography during spontaneous breathing, was evaluated before SCUF, at 12 h, and just after the cessation of the procedure. The IVCCI was calculated as follows: [(IVCD(max) - IVCD(min))/IVCD(max)] x 100. RESULTS: Mean UF time was 20.3 +/- 4.6 h with a mean volume of 287.6 +/- 96.2 ml h(-1) and a total ultrafiltrate production of 5,780.8 +/- 1,994.6 ml. No significant difference in MAP, HR, RR, and IVCD before and after UF was found. IVCCI increased significantly after UF (P < 0.001). Hypotension was observed only in those patients (2/24) who reached an IVCCI >30%. In all the other patients, a significant increase in IVCCI was obtained without any hemodynamic instability. CONCLUSION: IVC ultrasound is a rapid, simple, and non-invasive means for bedside monitoring of intravascular volume during SCUF and may guide fluid removal velocity.

Hyperkalemia induced failure of pacemaker capture and sensing.

Hyperkalemia may cause cardiac pacemaker (PMK) malfunctioning due to a reduction of the electronegativity of the resting myocardial potential. Both sensing and capture mechanisms could be temporarily affected, with possible life-threatening effects. Calcium chloride may counteract almost immediately such a dangerous effect of hyperkalemia, restoring the normal pacemaker function. We describe the case of a 75-year-old woman, observed in the Emergency Department for extreme weakness, very large QRS complexes, and a pacemaker type II exit block, associated with sensing failure and "spike-on-T" phenomenon. She was managed with immediate i.v. calcium chloride, followed by insulin/glucose and sodium bicarbonate infusions; the ECG recordings show an almost immediate correction of the PMK malfunctioning and serial improvement of the intraventricular conduction. This case supports the feasibility and effectiveness of i.v. calcium administration, as expected on the basis of electrophysiological ionized calcium effect on the threshold potential.