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.

Effects of fluids on microvascular perfusion in patients with severe sepsis.

PURPOSE: To evaluate the effects of fluid administration on microcirculatory alterations in sepsis. METHODS: With a Sidestream Dark Field device, we evaluated the effects of fluids on the sublingual microcirculation in 60 patients with severe sepsis. These patients were investigated either within 24 h (early, n = 37) or more than 48 h (late, n = 23) after a diagnosis of severe sepsis. Hemodynamic and microcirculatory measurements were obtained before and 30 min after administration of 1,000 ml Ringer's lactate (n = 29) or 400 ml 4% albumin (n = 31) solutions. RESULTS: Fluid administration increased perfused small vessel density from 3.5 (2.9-4.3) to 4.4 (3.7-4.9) n/mm (p < 0.01), through a combined increase in the proportion of perfused small vessels from 69 (62-76) to 79 (71-83) %, p < 0.01) and in small vessel density from 5.3 (4.4-5.9) to 5.6 (4.8-6.3) n/mm (p < 0.01). Importantly, microvascular perfusion increased in the early but not in the late phase of sepsis: the proportion of perfused small vessels increased from 65 (60-72) to 80 (75-84) % (p < 0.01) in the early phase and from 75 (66-80) to 74 (67-81) (p = ns) in the late phase. These microvascular effects of fluids were not related to changes in cardiac index (R(2) = 0.05, p = ns) or mean arterial pressure (R(2) = 0.04, p = ns). CONCLUSIONS: In this non-randomized trial, fluid administration improved microvascular perfusion in the early but not late phase of sepsis. This effect is independent of global hemodynamic effects and of the type of solution.

Microvascular response to red blood cell transfusion in patients with severe sepsis.

OBJECTIVES: Microvascular alterations may play a role in the development of multiple organ failure in severe sepsis. The effects of red blood cell transfusions on microvascular perfusion are not well defined. We investigated the effects of red blood cell transfusion on sublingual microvascular perfusion in patients with sepsis. DESIGN: Prospective, observational study. SETTING: A 31-bed, medical-surgical intensive care unit of a university hospital. PATIENTS: Thirty-five patients with severe sepsis requiring red blood cell transfusions. INTERVENTIONS: Transfusion of one to two units of leukocyte-reduced red blood cells. MEASUREMENTS AND MAIN RESULTS: The sublingual microcirculation was assessed with an Orthogonal Polarization Spectral device before and 1 hr after red blood cell transfusion. Red blood cell transfusions increased hemoglobin concentration from 7.1 (25th-75th percentile, 6.7-7.6) to 8.1 (7.5-8.6) g/dL (p < .01), mean arterial pressure from 75 (69-89) to 82 (75-90) mm Hg (p < .01), and oxygen delivery from 349 (278-392) to 391 (273-473) mL/min.M (p < .001). Microvascular perfusion was not significantly altered by transfusion, but there was considerable interindividual variation. The change in capillary perfusion after transfusion correlated with baseline capillary perfusion (Spearman-rho = -.49; p = .003). Capillary perfusion was significantly lower at baseline in patients who increased their capillary perfusion by >8% compared with those who did not (57 [52-64] vs. 75 [70-79]; p < .01), while hemodynamic and global oxygen transport variables were similar in the two groups. Red blood cell storage time had no influence on the microvascular response to red blood cell transfusion. CONCLUSIONS: The sublingual microcirculation is globally unaltered by red blood cell transfusion in septic patients; however, it can improve in patients with altered capillary perfusion at baseline.

Is compliance with hand disinfection in the intensive care unit related to work experience?

The performance of hand disinfection by staff in a 31-bed department of intensive care was monitored. During 32 hours of observation, 727 opportunities for hand disinfection were observed, and the compliance rate was 27.9%. The level of work experience was not correlated with hand disinfection compliance rates.

Prediction of postoperative complications after urgent laparotomy by intraperitoneal microdialysis: A pilot study.

OBJECTIVE: The aim of the present study was to investigate the role of intraperitoneal microdialysis (IPM) techniques in monitoring the evolution of postoperative critically ill patients requiring urgent laparotomy. SUMMARY BACKGROUND DATA: Postoperative intraabdominal sepsis is associated with an important degree of morbidity and mortality in acutely ill patients. Early diagnosis is critical to improve outcomes. METHODS: : The study included 25 consecutive patients admitted to the intensive care unit (ICU) after urgent laparotomy. Measurements of microdialysate fluid were performed through a microdialysis catheter, positioned intraperitoneally, during the first 5 postoperative days and lactate/pyruvate (L/P) ratios calculated. Patients were followed until hospital discharge. RESULTS: Ten patients had a complicated postoperative course, including 4 deaths (3 refractory shock, 1 mesenteric ischemia), 3 reinterventions (1 necrotic collection, 1 mesenteric ischemia, 1 biliary leak), 2 secondary peritonitis, and 1 intraabdominal collection. The IPM L/P ratio in these patients was already significantly higher during the first 24 postoperative hours compared with patients who had no complications (35 +/- 21 vs. 18 +/- 6, P < 0.01). An IPM L/P ratio above 22 on postoperative day 1 had a sensitivity of 0.64 and a specificity of 0.79 for complications. There were no significant differences between the two groups in pH, lactate, white blood cell count, or subcutaneous L/P ratio. No complication was associated with the technique. CONCLUSIONS: IPM is safe and reliable and provides valuable information after urgent laparotomy. Persistently high L/P values should raise the possibility of serious postoperative complications.

Effects of drotrecogin alfa activated on microcirculatory alterations in patients with severe sepsis.

OBJECTIVE: Microvascular alterations may play an important role in the development of sepsis-induced organ dysfunction. Drotrecogin alfa activated (DAA) improves outcome in patients with severe sepsis, but its precise mechanism of action is not entirely defined. We investigated whether DAA can influence microcirculatory alterations in patients with severe sepsis. DESIGN: Prospective, nonrandomized study. SETTING: A 31-bed, medico-surgical intensive care unit of a university hospital. PATIENTS: Forty adult patients with severe sepsis who met the EU criteria for DAA administration. INTERVENTIONS: Twenty patients received the drug (DAA) and 20 had a contraindication to DAA administration (control). MEASUREMENTS AND MAIN RESULTS: An orthogonal polarization spectral imaging technique was used to visualize the sublingual microcirculation. In all patients, measurements were obtained at baseline, 4 hrs later, and then every 24 hrs for up to 7 days. In patients receiving DAA, measurements were also obtained just before and 4 hrs after the end of DAA infusion. The two groups were well matched for severity of disease, number of failing organs, and the degree of microvascular alterations at baseline. The proportion of perfused capillaries increased in the DAA treated patients already at 4 hrs (from 64% [51-80%] to 84% [71-88%], p < .01) but not in the control group (from 67% [59-76%] to 68% [61-71%], p = not significant). Microvascular perfusion decreased transiently at the end of DAA infusion. The improvement in microvascular blood flow was associated with a more rapid resolution of hyperlactatemia. CONCLUSIONS: DAA administration rapidly improves sepsis-induced microvascular alterations, whereas its cessation is associated with a transient deterioration.

Infection control in the intensive care unit.

Nosocomial infections are common in many hospital departments, but particularly so on the intensive care unit, where they affect some 20 to 30% of patients. While early diagnosis and appropriate treatment are, of course, important, perhaps the greatest challenge is in the application of techniques to limit the development of such infections. This review will briefly discuss some of the background pathophysiology and epidemiology of nosocomial infection, and then focus on general and infection-specific preventative strategies individually and as part of broader infection-control programs with infection surveillance.