Mildly elevated lactate levels are associated with microcirculatory flow abnormalities and increased mortality: a microSOAP post hoc analysis.

BACKGROUND: Mildly elevated lactate levels (i.e., 1-2 mmol/L) are increasingly recognized as a prognostic finding in critically ill patients. One of several possible underlying mechanisms, microcirculatory dysfunction, can be assessed at the bedside using sublingual direct in vivo microscopy. We aimed to evaluate the association between relative hyperlactatemia, microcirculatory flow, and outcome. METHODS: This study was a predefined subanalysis of a multicenter international point prevalence study on microcirculatory flow abnormalities, the Microcirculatory Shock Occurrence in Acutely ill Patients (microSOAP). Microcirculatory flow abnormalities were assessed with sidestream dark-field imaging. Abnormal microcirculatory flow was defined as a microvascular flow index (MFI) < 2.6. MFI is a semiquantitative score ranging from 0 (no flow) to 3 (continuous flow). Associations between microcirculatory flow abnormalities, single-spot lactate measurements, and outcome were analyzed. RESULTS: In 338 of 501 patients, lactate levels were available. For this substudy, all 257 patients with lactate levels ≤ 2 mmol/L (median [IQR] 1.04 [0.80-1.40] mmol/L) were included. Crude ICU mortality increased with each lactate quartile. In a multivariable analysis, a lactate level > 1.5 mmol/L was independently associated with a MFI < 2.6 (OR 2.5, 95% CI 1.1-5.7, P = 0.027). CONCLUSIONS: In a heterogeneous ICU population, a single-spot mildly elevated lactate level (even within the reference range) was independently associated with increased mortality and microvascular flow abnormalities. In vivo microscopy of the microcirculation may be helpful in discriminating between flow- and non-flow-related causes of mildly elevated lactate levels. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01179243 . Registered on August 3, 2010.

International study on microcirculatory shock occurrence in acutely ill patients.

OBJECTIVES: Microcirculatory alterations are associated with adverse outcome in subsets of critically ill patients. The prevalence and significance of microcirculatory alterations in the general ICU population are unknown. We studied the prevalence of microcirculatory alterations in a heterogeneous ICU population and its predictive value in an integrative model of macro- and microcirculatory variables. DESIGN: Multicenter observational point prevalence study. SETTING: The Microcirculatory Shock Occurrence in Acutely ill Patients study was conducted in 36 ICUs worldwide. PATIENTS: A heterogeneous ICU population consisting of 501 patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographic, hemodynamic, and laboratory data were collected in all ICU patients who were 18 years old or older. Sublingual Sidestream Dark Field imaging was performed to determine the prevalence of an abnormal capillary microvascular flow index (< 2.6) and its additional value in predicting hospital mortality. In 501 patients with a median Acute Physiology and Chronic Health Evaluation II score of 15 (10-21), a Sequential Organ Failure Assessment score of 5 (2-8), and a hospital mortality of 28.4%, 17% exhibited an abnormal capillary microvascular flow index. Tachycardia (heart rate > 90 beats/min) (odds ratio, 2.71; 95% CI, 1.67-4.39; p < 0.001), mean arterial pressure (odds ratio, 0.979; 95% CI, 0.963-0.996; p = 0.013), vasopressor use (odds ratio, 1.84; 95% CI, 1.11-3.07; p = 0.019), and lactate level more than 1.5 mEq/L (odds ratio, 2.15; 95% CI, 1.28-3.62; p = 0.004) were independent risk factors for hospital mortality, but not abnormal microvascular flow index. In reference to microvascular flow index, a significant interaction was observed with tachycardia. In patients with tachycardia, the presence of an abnormal microvascular flow index was an independent, additive predictor for in-hospital mortality (odds ratio, 3.24; 95% CI, 1.30-8.06; p = 0.011). This was not true for nontachycardic patients nor for the total group of patients. CONCLUSIONS: In a heterogeneous ICU population, an abnormal microvascular flow index was present in 17% of patients. This was not associated with mortality. However, in patients with tachycardia, an abnormal microvascular flow index was independently associated with an increased risk of hospital death.

'Sepsis-related anemia' is absent at hospital presentation; a retrospective cohort analysis.

BACKGROUND: Anemia is a common feature during sepsis that occurs due to iatrogenic blood loss, depression of serum iron levels and erythropoietin production, and a decreased lifespan of erythrocytes. However, these mechanisms are unlikely to play a role in anemia at the start of sepsis. Moreover, sequestration of fluids, renal failure and increase of intravascular space may additionally influence the change in hemoglobin concentration during intravenous fluid administration in the acute phase of sepsis. METHODS: In this retrospective study, patients who were admitted acutely to the Intensive Care Unit (ICU) were included. Patients who fulfilled the international criteria for severe sepsis or septic shock were included in the sepsis group (S-group). The remaining patients were allocated to the control group (C-group). Laboratory data from blood samples taken at first presentation to the hospital and at admission to the ICU, the amount of intravenous fluid administration and length of stay in the emergency department were collected and tested for significant differences between groups. RESULTS: The difference in hemoglobin concentration between the S-group (n = 296) and C-group (n = 320) at first presentation in hospital was not significant (8.8 ± 1.2 versus 8.9 ± 1.2 mmol/l, respectively, p = 0.07). The reduction in hemoglobin concentration from the first presentation at the emergency department to ICU admission was significantly greater in the S-group compared to the C-group (1 [0.5-1.7] versus 0.5 [0.1-1.1] mmol/l, (p < 0.001)). Spearman rho correlation coefficients between the reduction in hemoglobin concentration and the amount of intravenous fluids administered or the creatinine level in the emergency department were significant (0.3 and 0.4, respectively, p < 0.001). In a multivariate regression analysis, creatinine, the amount of fluid administration and the presence of sepsis remained independently associated. CONCLUSIONS: Prior to in-hospital intravenous fluid administration, there is no significant difference in hemoglobin concentration between acute septic patients and acutely ill controls. Within several hours after hospital admission, there is a significant reduction in hemoglobin concentration, not only associated with the amount of intravenous fluids administered and the creatinine level, but also independently with sepsis itself.

Microvascular dysfunction in the surgical patient.

PURPOSE OF REVIEW: This review aims to describe recent research on perioperative microvascular alterations, with an emphasis on direct visualization of the human microcirculation. RECENT FINDINGS: Despite systemic haemodynamic optimization, perioperative complications are still occurring. In surgery, recent studies on both direct visualization of the microcirculation and indirect quantification of organ perfusion revealed that both the surgical procedure itself and perioperative interventions like anaesthesia, cardiopulmonary bypass, vasoactive drugs and fluid therapy may influence organ perfusion at the microvascular level. As in sepsis and heart failure, these perioperative microcirculatory abnormalities were associated with prognosis. However, whether these microcirculatory alterations are culprit or bystander in the process of developing perioperative complications remains to be established. SUMMARY: Recent research has elucidated the incidence of perioperative microvascular alterations, as well as its association with prognosis. Future research should further unravel the fascinating and complex interplay between the microcirculation and perioperative interventions.

Can celecoxib affect P-glycoprotein-mediated drug efflux? A microPET study.

INTRODUCTION: P-glycoprotein (Pgp) is an efflux pump that protects vital organs like the brain from toxic substances, but which is also associated with therapy resistance. The anti-inflammatory drug celecoxib potentiates the efficacy of several cytostatic and neurotropic drugs that are known Pgp substrates. To clarify whether Pgp is involved in the sensitizing effect of celecoxib, we investigated in vivo whether celecoxib is a substrate of Pgp and whether it can affect the efflux activity of the pump. METHODS: In control rats and in rats treated with the Pgp modulator cyclosporin A (CsA), cerebral accumulation of radiolabeled [(11)C]celecoxib was investigated by ex vivo biodistribution and micro-positron emission tomography imaging. In addition, the effect of unlabeled celecoxib and CsA (positive control) on the cerebral uptake of the Pgp substrate [(11)C]verapamil was studied. RESULTS: [(11)C]Celecoxib uptake in rat brain was relatively high and homogeneously distributed. Treatment of rats with CsA only marginally increased cerebral tracer uptake, which is most likely due to reduced tracer clearance from plasma. [(11)C]Verapamil brain uptake was more than 10-fold higher after treatment with CsA. In contrast, a high dose of celecoxib increased cerebral [(11)C]verapamil uptake only twofold, which was accompanied by a similar increase in tracer concentration in plasma. CONCLUSIONS: This study shows that celecoxib is not a substrate of Pgp and does not substantially affect the Pgp-mediated efflux of [(11)C]verapamil. Therefore, celecoxib-induced augmentation of the efficacy of chemotherapeutic and neurotropic drugs must be due to another mechanism than modulation of Pgp-mediated drug efflux.

Blood urea nitrogen (BUN) independently predicts mortality in critically ill patients admitted to ICU: A multicenter study.

BACKGROUND AND PURPOSE: The Microcirculatory Shock Occurrence in Acutely Ill Patients (micro-SOAP) study investigated associations of microcirculation and mortality. Risk stratification in critically ill patients is of utmost interest. Established score such as APACHE2 (Acute Physiology And Chronic Health Evaluation 2) are relatively complex and might therefore be of limited use. Blood urea nitrogen (BUN) was described to be associated with mortality in various diseases. We therefore aimed (i) to evaluate BUN for prediction of mortality in a cohort of critically ill patients and (ii) to investigate associations of BUN with microcirculation. METHODS: 412 patients were included in our post-hoc analysis of the prospective multicenter microSOAP study. Assesment of the sublingual microcirculation (Sidestream Dark Field (SDF) imaging) and collection of laboratory values were performed on the same day in this point prevalence study. Evaluation of associations with mortality was done by logistic regression analysis. An optimal BUN cut-off was calculated by means of the Youden Index. RESULTS: Median BUN was 9.0 mmol/L. BUN was associated with in-hospital-mortality in a logistic regression analysis (HR 1.03; 95% CI 1.01-1.05; p < 0.001). Per quartile (BUN 0-5.4 mmol/L, 5.4-9.0 mmol/L, 9.0-15.9 mmol/L and above 15.9 mmol/L) in-hospital mortality increased by as much as 51% (HR 1.51; 95% CI 1.23-1.85; p < 0.001). ROC analysis was done (AUC 0.63 95% CI 0.58-0.67) and the statistically optimal cut-off calculated by means of the Youden Index: 9.7 mmol/L. This cut-off was associated with a significant 3-fold increase in mortality (HR 2.97 95% CI 1.88-4.70; p < 0.001) and remained robustly associated with adverse outcome after correction for APACHE2 (HR 2.71 95% CI 1.61-4.59; p < 0.001), renal function as expressed by creatinine (HR 2.63 95% CI 1.59-4.33; p = 0.001), as well in an integrative model (MAP<60 mmHg, tachycardia (heart rate >90/min), lactate above 1.5 mmol/L, age above 80 years; HR 2.43 95% CI 1.50-3.92; p < 0.001). Parameters of microvascular perfusion were associated neither with BUN nor mortality. CONCLUSIONS: BUN is associated with hospital mortality and a combination of BUN and clinical signs might constitute a powerful but easy-to-use tool for risk stratification in critically ill patients and help improve their outcome. BUN was not associated with parameters of microcirculation which were not associated with mortality.

Effects of ketanserin on microcirculatory alterations in septic shock: An open-label pilot study.

INTRODUCTION: Microcirculatory alterations in sepsis are associated with increased morbidity and mortality. These alterations occur despite macrohemodynamic resuscitation. Alternative pro-microcirculatory strategies, including vasodilatory drugs, have been suggested to improve capillary blood flow. Ketanserin, a serotonin receptor antagonist, is an attractive candidate because of its vasodilatory, antithrombotic, and anti-inflammatory effects. METHODS: This is an open-label pilot study on the effect of ketanserin administration on microcirculatory alterations in septic shock, defined as microvascular flow index (MFI)≤2.5 after a strict macrohemodynamic resuscitation protocol. Sidestream dark-field imaging was applied to assess the microcirculation. A stepwise incremental dose regiment was applied until an MFI>2.9, the primary end point, was reached. RESULTS: Ten patients (Acute Physiology and Chronic Health Evaluation IV scores of 115 [100-136]) were included. Baseline MFI was 1.71 (1.31-2.32) and was significantly increasing to 2.96 (2.54-3.00; P=.021) during the ketanserin infusion. The total ketanserin dose was 0.09 (0.08-0.13) mg/kg per patient in 60 (30-60) minutes. In 3 patients (30%), the ketanserin infusion was discontinued due to refractory hypotension. CONCLUSION: An improvement in microcirculatory perfusion was observed during ketanserin administration in patients with septic shock after macrohemodynamic resuscitation. This finding needs further exploration in a placebo-controlled setting.

Microcirculatory perfusion and vascular reactivity are altered in post cardiac arrest patients, irrespective of target temperature management to 33 °C vs 36 °C.

AIM: In previous reports both microcirculatory alterations and impaired vascular reactivity have been described in post cardiac arrest patients treated with mild therapeutic hypothermia. As of now it is unknown whether these alterations are related to the temperature management or to the cardiac arrest itself. Aim of the present study was to investigate the potential difference in microcirculatory alterations and vascular reactivity in comatose patients after out of hospital cardiac arrest treated with target temperature management of 33 °C (TTM33) in comparison to patients treated with 36 °C (TTM36). METHODS: Our study was designed as a predefined substudy of the open label randomized controlled TTM trial in 2 Dutch mixed ICU's. Sublingual microvascular flow index (MFI) was assessed by Side Stream Darkfield imaging and vascular reactivity at the thenar region of the hand by near infrared spectroscopy. Variables, including systemic hemodynamics were recorded at start study (T1), after 12h (T2) and after 24h (T3). RESULTS: 22 patients were included, 13 in TTM33 and 9 in TTM36. At T1 MFI between groups did not differ significantly (1.08 [0.4-1.9] versus 1.67 [0.7-2.4] respectively, p = 0.59). The difference between groups remained insignificant over time. At T1 tissue oxygenation (StO2) was significantly lower in TTM36 in comparison to TTM33: (44.6 ± 15.8 versus 58.9 ± 13.5, p = 0.03). Over time this difference between groups disappeared. However, vascular reactivity, expressed as the descending and ascending slope of StO2 after a standardized ischemic occlusion test was similar between groups. CONCLUSIONS: In this relatively small sample size study microcirculatory blood flow and vascular reactivity did not differ nor change between TTM33 and TTM36.

Study Design of the Microcirculatory Shock Occurrence in Acutely Ill Patients (microSOAP): an International Multicenter Observational Study of Sublingual Microcirculatory Alterations in Intensive Care Patients.

Objective. Sublingual microcirculatory alterations are associated with an adverse prognosis in several critical illness subgroups. Up to now, single-center studies have reported on sublingual microcirculatory alterations in ICU patient subgroups, but an extensive evaluation of the prevalence of these alterations is lacking. We present the study design of an international multicenter observational study to investigate the prevalence of microcirculatory alterations in critically ill: the Microcirculatory Shock Occurrence in Acutely ill Patients (microSOAP). Methods. 36 ICU's worldwide have participated in this study aiming for inclusion of over 500 evaluable patients. To enable communication and data collection, a website, an Open Clinica 3.0 database, and image uploading software have been designed. A one-session assessment of the sublingual microcirculation using Sidestream Dark Field imaging and data collection on patient characteristics has been performed in every ICU patient >18 years, regardless of underlying disease. Statistical analysis will provide insight in the prevalence and severity of sublingual alterations, its relation to systemic hemodynamic variables, disease, therapy, and outcome. Conclusion. This study will be the largest microcirculation study ever performed. It is expected that this study will also establish a basis for future studies related to the microcirculation in critically ill.