Monitoring global volume-related hemodynamic or regional variables after initial resuscitation: What is a better predictor of outcome in critically ill septic patients?

HEMORRHAGIC SHOCK ASSESSED BY TISSUE MICROCIRCULATORY MONITORING: A NARRATIVE REVIEW

ABSTRACT

Hemorrhagic shock (HS) is a common complication after traumatic injury. Early identification of HS can reduce patients' risk of death. Currently, the identification of HS relies on macrocirculation indicators such as systolic blood pressure and heart rate, which are easily affected by the body's compensatory functions. Recently, the independence of the body's overall macrocirculation from microcirculation has been demonstrated, and microcirculation indicators have been widely used in the evaluation of HS. In this study, we reviewed the progress of research in the literature on the use of microcirculation metrics to monitor shock. We analyzed the strengths and weaknesses of each metric and found that microcirculation monitoring could not only indicate changes in tissue perfusion before changes in macrocirculation occurred but also correct tissue perfusion and cell oxygenation after the macrocirculation index returned to normal following fluid resuscitation, which is conducive to the early prediction and prognosis of HS. However, microcirculation monitoring is greatly affected by individual differences and environmental factors. Therefore, the current limitations of microcirculation assessments mean that they should be incorporated as part of an overall assessment of HS patients. Future research should explore how to better combine microcirculation and macrocirculation monitoring for the early identification and prognosis of HS patients.

Can central-venous oxygen saturation be estimated from tissue oxygen saturation during a venous occlusion test?

OBJECTIVE

To test whether tissue oxygen saturation (StO2) after a venous occlusion test estimates central venous oxygen saturation (ScvO2).

METHODS

Observational study in intensive care unit patients. Tissue oxygen saturation was monitored (InSpectra Tissue Spectrometer Model 650, Hutchinson Technology Inc., MN, USA) with a multiprobe (15/25mm) in the thenar position. A venous occlusion test in volunteers was applied in the upper arm to test the tolerability and pattern of StO2 changes during the venous occlusion test. A sphygmomanometer cuff was inflated to a pressure 30mmHg above diastolic pressure until StO2 reached a plateau and deflated to 0mmHg. Tissue oxygen saturation parameters were divided into resting StO2 (r-StO2) and minimal StO2 (m-StO2) at the end of the venous occlusion test. In patients, the cuff was inflated to a pressure 30mmHg above diastolic pressure for 5 min (volunteers' time derived) or until a StO2 plateau was reached. Tissue oxygen saturation parameters were divided into r-StO2, m-StO2, and the mean time that StO2 reached ScvO2. The StO2 value at the mean time was compared to ScvO2.

RESULTS

All 9 volunteers tolerated the venous occlusion test. The time for tolerability or the StO2 plateau was 7 ± 1 minutes. We studied 22 patients. The mean time for StO2 equalized ScvO2 was 100 sec and 95 sec (15/25mm probes). The StO2 value at 100 sec ([100-StO2] 15mm: 74 ± 7%; 25mm: 74 ± 6%) was then compared with ScvO2 (75 ± 6%). The StO2 value at 100 sec correlated with ScvO2 (15 mm: R2 = 0.63, 25mm: R2 = 0.67, p < 0.01) without discrepancy (Bland Altman).

CONCLUSION

Central venous oxygen saturation can be estimated from StO2 during a venous occlusion test.

Decreased peripheral perfusion measured by perfusion index is a novel indicator for cardiovascular death in patients with type 2 diabetes and established cardiovascular disease

Cardiovascular disease (CVD) is still the major cause of mortality in patients with type 2 diabetes. Despite of recent therapies, mortality and resources spent on healthcare due to CVD is still important problem. Thus, appropriate markers are needed to predict poor outcomes. Therefore, we investigated the role of peripheral perfusion as an indicator for cardiovascular death in patients with type 2 diabetes and established CVD. This retrospective cohort study included 1080 patients with type 2 diabetes and history of CVD recruited from the outpatient clinic at Matsushita Memorial Hospital in Osaka, Japan. Peripheral perfusion is assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. The median age and PI values were 74 years (range: 67-79 years) and 2.6% (range: 1.1-4.3%), respectively. During follow-up duration, 60 patients died due to CVD. The adjusted Cox regression analysis demonstrated that the risk of developing cardiovascular death was higher in the first quartile (Hazard ratio, 6.23; 95% CI, 2.28 to 22.12) or second quartile (Hazard ratio, 3.04; 95% CI, 1.46 to 6.85) of PI than that in the highest quartile (fourth quartile) of PI. PI (per 1% decrease) was associated with the development of cardiovascular death (Hazard ratio, 1.39; 95% CI, 1.16 to 1.68). PI could be a novel indicator of cardiovascular death in patients with type 2 diabetes and established CVD.

Lactate and lactate clearance in critically burned patients: usefulness and limitations as a resuscitation guide and as a prognostic factor

OBJECTIVE

Lactate levels to guide resuscitation in critically burned patients are controversial. The purpose of our study was to determine whether absolute lactate values or lower lactate clearance predict mortality, and whether these are useful tools in the resuscitation phase.

METHODS

We conducted a prospective, unicentric, observational study of a cohort of 214 burn patients admitted in the Burn Intensive Care Unit. We collected demographic and laboratory data, complications, absolute lactate levels and lactate clearance every 8 h since admission to 72 h. In critical patients we monitored hemodynamic parameters with transpulmonary thermodilution. We used Student's t-test or nonparametric tests, mixed models and Pearson and Spearman methods, Fisher's exact and chi-squared test.

RESULTS

Of the 214 patients, 76.6% were male, mean age were 46 ± 15 years and 23.0 ± 19.5% of Total Basal Surface Area (TBSA) burned. Initial mean absolute levels of lactate were 2.02 ± 1.62 mmol/L in survivors vs. 4.05 ± 3.90 mmol/L in nonsurvivors. Initial elevated lactate levels increased mortality (p < .001), length of ICU stay, mechanical ventilation and shock. In the subgroup of burned TBSA < 20%, lowering the lactate cut-off point from 2.0 to 1.8 mmol/L improved the mortality prediction (OR:9.3). We found no relationship between lactate clearance in the first 24 h and mortality. In more severe patients (> 20% TBSA burned and initial lactate levels > 2), a good correlation was found between lactate and cardiac index; but not with intrathoracic blood volume index (ITBVI). Patients with low ITBVI preload (< 600 mL/m²) did not show significant differences in lactate clearance compared with those with ITBVI > 600.

CONCLUSIONS

Initial elevated lactate levels are a factor of poor prognosis and the cut-off point that best predicts mortality should be adjusted in the patients with TBSA burned < 20%. The global clearance of lactate in the first 24 h, unlike what occurs in other injuries, does not correlate with mortality. Monitoring lactate can ensure adequate peripheral perfusion during resuscitation with lower than normal fluid preload values.

Fluid overload in patients with septic shock and lactate clearance as a therapeutic goal: a retrospective cohort study

OBJECTIVE

To assess whether fluid overload in fluid therapy is a prognostic factor for patients with septic shock when adjusted for lactate clearance goals.

METHODS

This was a retrospective cohort study conducted at a level IV care hospital in Bogotá, Colombia. A cohort of patients with septic shock was assembled. Their characteristics and fluid balance were documented. The patients were stratified by exposure levels according to the magnitude of fluid overload by body weight after 24 hours of therapy. Mortality was determined at 30 days, and an unconditional logistic regression model was created, adjusting for confounders. The statistical significance was established at p ≤ 0.05.

RESULTS

There were 213 patients with septic shock, and 60.8% had a lactate clearance ≥ 50% after treatment. Ninety-seven (46%) patients developed fluid overload ≥ 5%, and only 30 (13%) developed overload ≥ 10%. Patients exhibiting fluid overload ≥ 5% received an average of 6227mL of crystalloids (SD ± 5838mL) in 24 hours, compared to 3978mL (SD ± 3728mL) among unexposed patients (p = 0.000). The patients who developed fluid overload were treated with mechanical ventilation (70.7% versus 50.8%) (p = 0.003), albumin (74.7% versus 55.2%) (p = 0.003) and corticosteroids (53.5% versus 35.0%) (p = 0.006) more frequently than those who did not develop fluid overload. In the multivariable analysis, cumulative fluid balance was not associated with mortality (OR 1.03; 95%CI 0.89 - 1.20).

CONCLUSIONS

Adjusting for the severity of the condition and adequate lactate clearance, cumulative fluid balance was not associated with increased mortality in this Latin American cohort of septic patients.

Decreased microcirculatory function measured by perfusion index is predictive of cardiovascular death

BACKGROUND

The importance of microcirculation for adverse outcomes in the early phase of critical illnesses has been reported. Microcirculatory function is assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. We investigated the correlation between PI and cardiovascular death to explore whether it can serve as a predictor of cardiovascular death.

METHODS AND RESULTS

This retrospective study included 2171 patients admitted to Matsushita Memorial Hospital in Osaka, Japan, for medical treatment. We measured PI for all patients. To examine the effects of PI on cardiovascular death, a Cox proportional hazard model was used. The median age and PI values were 72 years (range 63-79 years) and 2.7% (range 1.4-4.6%), respectively. During the 3927.7 person-years follow-up period, a total of 54 patients died due to cardiovascular disease. PI was positively correlated with BMI (P < 0.0001) and total cholesterol levels (P = 0.004). PI was negatively correlated with age (P < 0.0001), heart rate (P < 0.0001), and creatinine levels (P < 0.0001). Adjusted Cox regression analyses demonstrated that PI was associated with an increased hazard of cardiovascular death (hazard ratio 0.84; 95% CI; range 0.72-0.99). In addition, compared with patients with a high PI (> 3.7%), those with a low PI (≤ 2.0%) had a significantly increased risk of cardiovascular death. This low PI group had a hazard ratio of 3.49 (95% CI 1.73-7.82).

CONCLUSIONS

The PI is a valuable predictor for cardiovascular death in a clinical setting.

Resuscitation incoherence and dynamic circulation-perfusion coupling in circulatory shock

OBJECTIVE

Poor tissue perfusion/cellular hypoxia may persist despite restoration of the macrocirculation (Macro). This article reviewed the literatures of coherence between hemodynamics and tissue perfusion in circulatory shock.

DATA SOURCES

We retrieved information from the PubMed database up to January 2018 using various search terms or/and their combinations, including resuscitation, circulatory shock, septic shock, tissue perfusion, hemodynamic coherence, and microcirculation (Micro).

STUDY SELECTION

The data from peer-reviewed journals printed in English on the relationships of tissue perfusion, shock, and resuscitation were included.

RESULTS

A binary (coherence/incoherence, coupled/uncoupled, or associated/disassociated) mode is used to describe resuscitation coherence. The phenomenon of resuscitation incoherence (RI) has gained great attention. However, the RI concept requires a more practical, systematic, and comprehensive framework for use in clinical practice. Moreover, we introduce a conceptual framework of RI to evaluate the interrelationship of the Macro, Micro, and cell. The RI is divided into four types (Type 1: Macro-Micro incoherence + impaired cell; Type 2: Macro-Micro incoherence + normal cell; Type 3: Micro-Cell incoherence + normal Micro; and Type 4: both Macro-Micro and Micro-cell incoherence). Furthermore, we propose the concept of dynamic circulation-perfusion coupling to evaluate the relationship of circulation and tissue perfusion during circulatory shock.

CONCLUSIONS

The concept of RI and dynamic circulation-perfusion coupling should be considered in the management of circulatory shock. Moreover, these concepts require further studies in clinical practice.

Liver function assessment by indocyanine green plasma disappearance rate in patients with intra-abdominal hypertension after "non-hepatic" abdominal surgery

BACKGROUND AND OBJECTIVE

Liver function assessment in patients with intra-abdominal hypertension (IAH) after major abdominal surgery is complex and often confounding. Elevated intra-abdominal pressure (IAP) often occurs after major abdominal surgery, and is associated with decreased abdominal blood flow and organ dysfunction, and it could cause abdominal compartment syndrome (ACS), which is a life-threatening condition. Plasma disappearance rate (PDR) of indocyanine green (ICG) and ICG retention rate after 15 min (R15) were used to evaluate liver function and as a prognostic parameter after major abdominal surgery.

METHODS

In this prospective/observational study, 51 patients were followed in the surgical intensive care unit after major abdominal surgery (operation of the small and large intestine, stomach, pancreas, spleen, or resection of the abdominal aorta), 29 had IAH. The PDR-ICG and R15 were analyzed 24 h after surgery concurrently with IAP, APP, bilirubin, AST, ALT, prothrombin time, albumin, cardiac index, arterial lactate, oxygen delivery, MAP (mean arterial pressure), APACHE II (acute physiology and chronic health evaluation), SOFA (sequential organ failure assessment), and SAPS II (simplified acute physiology score). IAH has been defined as a peak intra-abdominal pressure (IAP) value of ≥12 mmHg, at a minimum, as two standardized measurements obtained 1-6 h apart.

RESULTS

The PDR-ICG measured 24 h after surgery was not different among groups (20.95% [SD = 10.34] vs 25.40% [SD = 7.42]), p = .094. ICG R15 was significantly higher in patients with IAH, 11.10% [SD = 13.82] vs 8.30 [SD = 11.46], p < .05, respectively. The PDR/ICG value was significantly lower in non-survivors than survivors (16.82 [SD = 10.87] vs 24.35 [SD = 8.48], p < .05).

CONCLUSIONS

The results suggest that PDR/ICG and ICG R15 are useful dynamic tests for evaluation of complex liver function and survival prediction after major abdominal surgery in patients with IAH.

Oxygen-Flow-Pressure Targets for Resuscitation in Critical Hemodynamic Therapy

Far from traditional "vital signs," the field of hemodynamic monitoring (HM) is rapidly developing. However, it is also easy to misunderstand hemodynamic therapy as merely HM and some concrete bundles or guidelines for circulation support. Here, we describe the concept of "critical hemodynamic therapy" and clarify the concepts of the "therapeutic target" and "therapeutic endpoint" in clinical practice. Three main targets (oxygen delivery, blood flow, perfusion pressure) for resuscitation are reviewed in critically ill patients according to the sepsis guidelines and hemodynamic consensus. ScvO2 at least 70% has not been recommended as a directed target for initial resuscitation, and the directed target of mean arterial pressure (MAP) still is 65 mmHg. Moreover, the individual MAP target is underlined, and using flow-dependent monitoring to guide fluid infusion is recommended. The flow-directed target for fluid infusion might be a priority, but it remains controversial in resuscitation. The interpretation of these targets is necessary for adequate resuscitation and the correction of tissue hypoxia. The incoherence phenomenon of resuscitation (macrocirculation and microcirculation, tissue perfusion, and cellular oxygen utilization) is gaining increased attention, and early identification of these incoherences might be helpful to reduce the risk of over-resuscitation.

A restrictive dose of crystalloids in patients during laparoscopic cholecystectomy is safe and cost-effective: prospective, two-arm parallel, randomized controlled trial

Purpose

There are no evidence-based guidelines for volume replacement during surgical procedures such as laparoscopic cholecystectomy. However, the administration of a restrictive volume of crystalloids could be more cost-effective and safe. This trial aimed to determine the effectiveness and safety of a restrictive regimen of crystalloids in patients during laparoscopic cholecystectomy by analyzing its cost-effectiveness and 1-year morbidity rate.

Patients and methods

In this randomized, prospective study, patients were assigned to one of three groups based on the volume of fluid administered: the restrictive group received 1 mL/kg/hr, the low liberal group received 5 mL/kg/hr, and the high liberal group received 15 mL/kg/hr of Ringer’s solution intraoperatively. There were 40 patients in each group. Each patient’s hemodynamic parameters and laboratory values (arterial blood gas and lactate levels) were measured together with their consumption of crystalloids, volatile anesthetics, and analgesics.

Results

Analysis of the hemodynamic and laboratory parameters revealed no signs of global hypoperfusion in any of the groups analyzed. There was no significant difference in the duration of surgery and anesthesia, but the consumption of crystalloids, volatile anesthetics, and opioids was significantly lower in the restrictive group, compared with the low and high liberal groups. Although there was no significant difference in the 1-year morbidity among the groups, heart failure was observed in one patient in the high liberal group in the early postoperative period.

Conclusion

Restrictive fluid therapy during laparoscopic cholecystectomy is justified, safe, and more cost-effective than other options.

Assessment of liver perfusion and function by indocyanine green in the perioperative setting and in critically ill patients

Indocyanine green (ICG) is a water-soluble dye that is bound to plasma proteins when administered intravenously and nearly completely eliminated from the blood by the liver. ICG elimination depends on hepatic blood flow, hepatocellular function and biliary excretion. ICG elimination is considered as a useful dynamic test describing liver function and perfusion in the perioperative setting, i.e., in liver surgery and transplantation, as well as in critically ill patients. ICG plasma disappearance rate (ICG-PDR) which can be measured today by transcutaneous systems at the bedside is a valuable method for dynamic assessment of liver function and perfusion, and is regarded as a valuable prognostic tool in predicting survival of critically ill patients, presenting with sepsis, ARDS or acute liver failure.

Impact of hemodynamic goal-directed resuscitation on mortality in adult critically ill patients: a systematic review and meta-analysis

The effect of hemodynamic optimization in critically ill patients has been challenged in recent years. The aim of the meta-analysis was to evaluate if a protocolized intervention based on the result of hemodynamic monitoring reduces mortality in critically ill patients. We performed a systematic review and meta-analysis according to the Cochrane Handbook for Systematic Reviews of Interventions. The study was registered in the PROSPERO database (CRD42015019539). Randomized controlled trials published in English, reporting studies on adult patients treated in an intensive care unit, emergency department or equivalent level of care were included. Interventions had to be protocolized and based on results from hemodynamic measurements, defined as cardiac output, stroke volume, stroke volume variation, oxygen delivery, and central venous-or mixed venous oxygenation. The control group had to be treated without any structured intervention based on the parameters mentioned above, however, monitoring by central venous pressure measurements was allowed. Out of 998 screened papers, thirteen met the inclusion criteria. A total of 3323 patients were enrolled in the six trials with low risk of bias (ROB). The mortality was 22.4% (374/1671 patients) in the intervention group and 22.9% (378/1652 patients) in the control group, OR 0.94 with a 95% CI of 0.73–1.22. We found no statistically significant reduction in mortality from hemodynamic optimization using hemodynamic monitoring in combination with a structured algorithm. The number of high quality trials evaluating the effect of protocolized hemodynamic management directed towards a meaningful treatment goal in critically ill patients in comparison to standard of care treatment is too low to prove or exclude a reduction in mortality.

A randomized trial comparing terlipressin and noradrenaline in patients with cirrhosis and septic shock

BACKGROUND & AIMS

The choice of vasopressor for treating cirrhosis with septic shock is unclear. While noradrenaline in general is the preferred vasopressor, terlipressin improves microcirculation in addition to vasopressor action in non-cirrhotics. We compared the efficacy and safety of noradrenaline and terlipressin in cirrhotics with septic shock.

PATIENTS AND METHODS

Cirrhotics with septic shock underwent open label randomization to receive either terlipressin (n=42) or noradrenaline (n=42) infusion at a titrated dose. The primary outcome was mean arterial pressure (MAP) >65 mm Hg at 48 h.

RESULTS

Baseline characteristics were comparable between the terlipressin and noradrenaline groups.SBP and pneumonia were major sources of sepsis. A higher proportion of patients on terlipressin were able to achieve MAP >65 mm of Hg (92.9% vs 69.1% P=.005) at 48 h. Subsequent discontinuation of vasopressor after hemodynamic stability was better with terlipressin (33.3% vs 11.9%, P<.05). Terlipressin compared to noradrenaline prevented variceal bleed (0% vs 9.5%, P=.01) and improved survival at 48 h (95.2% vs 71.4%, P=.003). Percentage lactate clearance (LC) is an independent predictor of survival [P=.0001, HR=3.9 (95% CI: 1.85-8.22)] after achieving the target MAP.Therapy related adverse effect were comparable in both the arms (40.5% vs 21.4%, P=.06), mostly minor (GradeII-88%) and reversible.

CONCLUSIONS

Terlipressin is as effective as noradrenaline as a vasopressor in cirrhotics with septic shock and can serve as a useful drug. Terlipressin additionally provides early survival benefit and reduces the risk of variceal bleed. Lactate clearance is a better predictor of outcome even after achieving target MAP, suggesting the role of microcirculation in septic shock.

Hepatic Perfusion Alterations in Septic Shock Patients: Impact of Early Goal-directed Therapy

BACKGROUND

Early goal-directed therapy (EGDT) has become an important therapeutic management in early salvage stage of septic shock. However, splenic organs possibly remained hypoperfused and hypoxic despite fluid resuscitation. This study aimed to evaluate the effect of EGDT on hepatic perfusion in septic shock patients.

METHODS

A prospective observational study was carried out in early septic shock patients who were admitted to Intensive Care Unit within 24 h after onset and who met all four elements of the EGDT criteria after treatment with the standard EGDT procedure within 6 h between December 1, 2012 and November 30, 2013. The hemodynamic data were recorded, and oxygen metabolism and hepatic functions were monitored. An indocyanine green clearance test was applied to detect the hepatic perfusion. The patients' characteristics were compared before treatment (T0), immediately after EGDT (T1), and 24 h after EGDT (T2). This study is registered at ClinicalTrials.org, NCT02060773.

RESULTS

Twenty-one patients were included in the study; however, the hepatic perfusion data were not included in the analysis for two patients; therefore, 19 patients were eligible for the study. Hemodynamics data, as monitored by pulse-indicator continuous cardiac output, were obtained from 16 patients. There were no significant differences in indocyanine green plasma disappearance rate (ICG-PDR) and 15-min retention rate (R15) at T0 (11.9 ± 5.0%/min and 20.0 ± 13.2%), T1 (11.4 ± 5.1%/min and 23.6 ± 14.9%), and T2 (11.0 ± 4.5%/min and 23.7 ± 15.3%) (all P > 0.05). Both of the alterations of ICG-PDR and R15 showed no differences at T0, T1, and T2 in the patients of different subgroups that achieved different resuscitation goal numbers when elected (P > 0.05).

CONCLUSION

There were no hepatic perfusion improvements after EGDT in the early phase of patients with septic shock.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02060773 (https://clinicaltrials.gov/ct2/show/NCT02060773).

Microcirculatory monitoring in septic patients: Where do we stand?

Microcirculatory alterations play a pivotal role in sepsis-related morbidity and mortality. However, since the microcirculation has been a "black box", current hemodynamic management of septic patients is still guided by macrocirculatory parameters. In the last decades, the development of several technologies has shed some light on microcirculatory evaluation and monitoring, and the possibility of incorporating microcirculatory variables to clinical practice no longer seems to be beyond reach. The present review provides a brief summary of the current technologies for microcirculatory evaluation, and attempts to explore the potential role and benefits of their integration to the resuscitation process in critically ill septic patients.

Lactate clearance as the predictor of outcome in pediatric septic shock

CONTEXT

Septic shock can rapidly evolve into multiple system organ failure and death. In the recent years, hyperlactatemia has been found to be a risk factor for mortality in critically ill adults.

AIMS

To evaluate the predictive value of lactate clearance and to determine the optimal cut-off value for predicting outcome in children with septic shock.

SETTINGS AND DESIGN

A prospective observational study was performed on children with septic shock admitted to pediatric Intensive Care Unit (PICU).

SUBJECTS AND METHODS

Serial lactate levels were measured at PICU admission, 24 and 48 h later. Lactate clearance, percent decrease in lactate level in 24 h, was calculated. The primary outcome measure was survival or nonsurvival at the end of hospital stay. We performed receiver operating characteristic analyses to calculate optimal cut-off values.

RESULTS

The mean lactate levels at admission were significantly higher in the nonsurvivors than survivors, 5.12 ± 3.51 versus 3.13 ± 1.71 mmol/L (P = 0.0001). The cut-off for lactate level at admission for the best prediction of mortality was determined as ≥4 mmol/L (odds ratio 5.4; 95% confidence interval [CI] =2.45-12.09). Mean lactate clearance was significantly higher in survivors than nonsurvivors (17.9 ± 39.9 vs. -23.2 ± 62.7; P < 0.0001). A lactate clearance rate of <10% at 24 h had a sensitivity and specificity of 78.7% and 72.2%, respectively and a positive predictive value of 83.1% for death. Failure to achieve a lactate clearance of more than 10% was associated with greater risk of mortality (likelihood ratio + 2.83; 95% CI = 1.82-4.41).

CONCLUSIONS

Serial lactate levels can be used to predict outcome in pediatric septic shock. A 24 h lactate clearance cut-off of <10% is a predictor of in-hospital mortality in such patients.

The handheld blood lactate analyser versus the blood gas based analyser for measurement of serum lactate and its prognostic significance in severe sepsis

BACKGROUND

This study was done to compare the accuracy of the Lactate Pro LT 1710 (Arkray Inc., Kyoto, Japan) with the Combiline Plus (Eschweiler GmbH & Co. KG Holzkoppelweg, Kiel, Germany), and also, to analyze the prognostic significance of serum lactates and Simplified Acute Physiology Score 3 (SAPS 3) in patients of severe sepsis.

METHODS

106 patients of severe sepsis admitted to the ICU were screened. The serum lactate from an arterial sample analyzed in both the machines was recorded at admission and at 48 h. These patients were then followed up to the 28th day for mortality.

RESULTS

The Lactate Pro LT 1710 handheld point of care lactate meter provides consistent results comparable to the Eschweiler Combiline blood gas analyser. Serum lactate concentration was significantly higher in nonsurvivors at the time of admission (3.30 ± 1.26) and at 48 h (4.34 ± 1.73). Lactate clearance at 48 h appears to be a better predictor of mortality than the lactate levels at 0 h and 48 h. The mean SAPS 3 at admission amongst survivors was significantly less as compared to nonsurvivors. The SAPS 3 had improved to 47.44 (±11.79) in survivors at 48 h, while in nonsurvivors it had worsened to 81.98 (±12.32) (p = 0.00); thus, a worsening SAPS 3 at 48 h had a poorer prognosis.

CONCLUSIONS

The Lactate Pro LT 1710 provides similar results to the Combiline Eschweiler blood gas analyser and is a cheaper alternative. It would prove to be a boon in peripheral hospitals in the aggressive management of critically ill patients.

Instrument to detect syncope and the onset of shock

Currently the diagnosis of hemorrhagic shock is essentially clinical, relying on the expertise of nurses and doctors. One of the first measurable physiological changes that marks the onset of hemorrhagic shock is a decrease in capillary blood flow. Diffuse correlation spectroscopy (DCS) quantifies this decrease. DCS collects and analyzes multiply scattered, coherent, near infrared light to assess relative blood flow. This work presents a preliminary study using a DCS instrument with human subjects undergoing a lower body negative pressure (LBNP) protocol. This work builds on previous successful DCS instrumentation development and we believe it represents progress toward understanding how DCS can be used in a clinical setting.

Hemodynamic monitoring in the intensive care unit: a Brazilian perspective

OBJECTIVE

In Brazil, there are no data on the preferences of intensivists regarding hemodynamic monitoring methods. The present study aimed to identify the methods used by national intensivists, the hemodynamic variables they consider important, the regional differences, the reasons for choosing a particular method, and the use of protocols and continued training.

METHODS

National intensivists were invited to answer an electronic questionnaire during three intensive care events and later, through the Associação de Medicina Intensiva Brasileira portal, between March and October 2009. Demographic data and aspects related to the respondent preferences regarding hemodynamic monitoring were researched.

RESULTS

In total, 211 professionals answered the questionnaire. Private hospitals showed higher availability of resources for hemodynamic monitoring than did public institutions. The pulmonary artery catheter was considered the most trusted by 56.9% of the respondents, followed by echocardiograms, at 22.3%. Cardiac output was considered the most important variable. Other variables also considered relevant were mixed/central venous oxygen saturation, pulmonary artery occlusion pressure, and right ventricular end-diastolic volume. Echocardiography was the most used method (64.5%), followed by pulmonary artery catheter (49.3%). Only half of respondents used treatment protocols, and 25% worked in continuing education programs in hemodynamic monitoring.

CONCLUSION

Hemodynamic monitoring has a greater availability in intensive care units of private institutions in Brazil. Echocardiography was the most used monitoring method, but the pulmonary artery catheter remains the most reliable. The implementation of treatment protocols and continuing education programs in hemodynamic monitoring in Brazil is still insufficient.

Current use and perspective of indocyanine green clearance in liver diseases

Indocyanine green (ICG) is a water-soluble anionic compound that binds to plasma proteins after intravenous administration. It is selectively taken up at the first pass by hepatocytes and excreted unchanged into the bile. With the development of ICG elimination measurement by spectrophotometry, the ICG retention test has become a safe, rapid, reproducible, inexpensive and noninvasive tool for the assessment of liver function. Clinical evidence suggests that the ICG retention test can enable the establishment of tailored management strategies by providing prognostic information. In particular, this method has been evaluated as a prognostic marker in patients with advanced cirrhosis or awaiting liver transplantation. In addition, it is used as a marker of portal hypertension in cirrhotic patients, as a prognostic factor in intensive care units and for the assessment of liver function in patients undergoing liver surgery. Since recent technology enables ICG-PDR to be measured noninvasively at the bedside, this parameter is an attractive addition to liver function and regional haemodynamic monitoring. However, the current state-of-the-art as concerns this technology remains at a low level of evidence and thorough assessment is required.

Clinical classification of tissue perfusion based on the central venous oxygen saturation and the peripheral perfusion index

Introduction

We investigated whether combining the peripheral perfusion index (PI) and central venous oxygen saturation(ScvO₂) would identify subsets of patients for assessing the tissue perfusion and predicting outcome during the resuscitation in critically ill patients.

Methods

A total of 202 patients with central venous catheters for resuscitation were enrolled in this prospective observational study. The arterial, central venous blood gas and the PI were measured simultaneously at the enrollment (T0) and 8 h (T8) after early resuscitation. Based on the distribution of the PI in healthy population, a cutoff of PI ≥1.4 was defined as a normal PI. Moreover, the critical value of PI was defined as the best cutoff value related to the mortality in the study population. The PI impairment stratification is defined as follows: a normal PI(≥1.4), mild PI impairment (critical value < PI < 1.4) and critical PI impairment (PI ≤ critical value).

Results

The PI at T8 was with the greatest AUC for prediction the 30-day mortality and PI is an independent risk factor for 30-day mortality. Moreover, a cutoff of PI < 0.6 is related to poor outcomes following resuscitation. So, based on cutoffs of ScvO₂ (70 %) and critical PI (0.6) at T8, we assigned the patients to four categories: group 1 (PI ≤ 0.6 on ScvO₂ < 70 %), group 2 (PI ≤ 0.6 on ScvO₂ ≥ 70 %), group 3 (PI > 0.6 on ScvO₂ < 70 %), and group 4 (PI > 0.6 on ScvO₂ ≥ 70 %). The combination of low ScvO₂(<70 %) and PI(≤0.6) was associated with the lowest survival rates at 30 days [log rank (Mantel–Cox) = 87.518, p < 0.0001]. The sub-group patients who had high ScvO₂(>80 %) at T8 were with low mortality and high PI. Moreover, the normal PI (≥1.4) did not show a better outcome than mild impaired PI (0.6-1.4) patients who had a normalized ScvO₂(>70 %) after resuscitation. The PI was correlated with the lactate, P(v-a)CO₂, and ScvO₂ in all the measurements (n = 404). These relationships are strengthened with abnormal PI (PI < 1.4) but not with normal PI (PI ≥ 1.4).

Conclusion

Complementing ScvO₂ assessment with PI can better identify endpoints of resuscitation and adverse outcomes. Pursuing a normalized PI (≥1.4) may not result in better outcomes for a mild impaired PI after ScvO₂ is normalized.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1057-8) contains supplementary material, which is available to authorized users.

Arginine infusion in patients with septic shock increases nitric oxide production without haemodynamic instability

Arginine deficiency in sepsis may impair nitric oxide (NO) production for local perfusion and add to the catabolic state. In contrast, excessive NO production has been related to global haemodynamic instability. Therefore, the aim of the present study was to investigate the dose-response effect of intravenous arginine supplementation in post-absorptive patients with septic shock on arginine-NO and protein metabolism and on global and regional haemodynamics. Eight critically ill patients with a diagnosis of septic shock participated in this short-term (8 h) dose-response study. L-Arginine-HCl was continuously infused [intravenously (IV)] in three stepwise-increasing doses (33, 66 and 99 μmol·kg-1·h-1). Whole-body arginine-NO and protein metabolism were measured using stable isotope techniques, and baseline values were compared with healthy controls. Global and regional haemodynamic parameters were continuously recorded during the study. Upon infusion, plasma arginine increased from 48±7 to 189±23 μmol·l-1 (means±S.D.; P<0.0001). This coincided with increased de novo arginine (P<0.0001) and increased NO production (P<0.05). Sepsis patients demonstrated elevated protein breakdown at baseline (P<0.001 compared with healthy controls), whereas protein breakdown and synthesis both decreased during arginine infusion (P<0.0001). Mean arterial and pulmonary pressure and gastric mucosal-arterial partial pressure of carbon dioxide difference (Pr-aCO2) gap did not alter during arginine infusion (P>0.05), whereas stroke volume (SV) increased (P<0.05) and arterial lactate decreased (P<0.05). In conclusion, a 4-fold increase in plasma arginine with intravenous arginine infusion in sepsis stimulates de novo arginine and NO production and reduces whole-body protein breakdown. These potential beneficial metabolic effects occurred without negative alterations in haemodynamic parameters, although improvement in regional perfusion could not be demonstrated in the eight patients with septic shock who were studied.

[Indocyanine green elimination for the evaluation of liver function: prognostic value in patients with community-acquired sepsis]

BACKGROUND

The aim of our clinical study was to correlate liver function measured by indocyanine green (ICG) elimination and clinical outcomes in patients with an early stage of community-acquired sepsis (CAS).

MATERIALS AND METHODS

A total of 341 patients (≥ 18 years) presenting with suspicion of CAS or evidence of an infection and fulfillment of ≥ 2 systemic inflammatory response syndrome (SIRS) criteria were included in the observational study"Prognosis of early sepsis 2" (Prognose der frühen Sepsis 2, ProFS 2). Patients who had been hospitalized within the last 7 days were excluded. In a subgroup of these patients (n = 72) who were transferred to an intensive or intermediate care unit according to the clinical judgment of the treating physicians, ICG elimination (plasma disappearance rate, ICG-PDR; 15 min retention rate, ICG-R15) was assessed by using a noninvasive monitoring system (LiMON, PULSION Medical Systems, Germany). ICG-PDR and -R15 were determined on the day of admission (n = 72) and after 96 h (n = 34). The primary end point of the study was defined as death within 30 days. Secondary endpoints were need for renal replacement therapy, requirement for invasive mechanical ventilation, and length of stay in an intermediate or intensive care unit.

RESULTS AND CONCLUSION

In contrast to patients with sepsis or severe sepsis, ICG elimination was found to be significantly impaired in patients with septic shock. Furthermore, a significant predictive value of ICG-PDR and -R15 on the day of admission for the need for subsequent renal replacement therapy (n = 12) was observed. In addition, reduced ICG elimination was associated with a longer stay in an intermediate or intensive care unit. However, ICG elimination on admission could not predict 30-day mortality (n = 14) or requirement of mechanical ventilation (n = 20).

Diagnostic characteristics of a clinical screening tool in combination with measuring bedside lactate level in emergency department patients with suspected sepsis

BACKGROUND

Early identification of sepsis and initiation of aggressive treatment saves lives. However, the diagnosis of sepsis may be delayed in patients without overt deterioration. Clinical screening tools and lactate levels may help identify sepsis patients at risk for adverse outcomes.

OBJECTIVES

The objective was to determine the diagnostic characteristics of a clinical screening tool in combination with measuring early bedside point-of-care (POC) lactate levels in emergency department (ED) patients with suspected sepsis.

METHODS

This was a prospective, observational study set at a suburban academic ED with an annual census of 90,000. A convenience sample of adult ED patients with suspected infection were screened with a sepsis screening tool for the presence of at least one of the following: temperature greater than 38°C or less than 36°C, heart rate greater than 90 beats/min, respiratory rate greater than 20 breaths/min, or altered mental status. Patients meeting criteria had bedside POC lactate testing following triage, which was immediately reported to the treating physician if ≥2.0 mmol/L. Demographic and clinical information, including lactate levels, ED interventions, and final diagnosis, were recorded. Outcomes included presence or absence of sepsis using the American College of Chest Physicians/Society of Critical Care Medicine consensus conference definitions and intensive care unit (ICU) admissions, use of vasopressors, and mortality. Diagnostic test characteristics were calculated using 2-by-2 tables with their 95% confidence intervals (CIs). The association between bedside lactate and ICU admissions, use of vasopressors, and mortality was determined using logistic regression.

RESULTS

A total of 258 patients were screened for sepsis. Their mean (± standard deviation [SD]) age was 64 (±19) years; 46% were female, and 82% were white. Lactate levels were 2.0 mmol/L or greater in 80 (31%) patients. Patients were confirmed to meet sepsis criteria in 208 patients (81%). The diagnostic characteristics for sepsis of the combined clinical screening tool and bedside lactates were sensitivity 34% (95% CI = 28% to 41%), specificity 82% (95% CI = 69% to 90%), positive predictive value 89% (95% CI = 80% to 94%), and negative predictive value 23% (95% CI = 17% to 30%). Bedside lactate levels were associated with sepsis severity (p < 0.001), ICU admission (odds ratio [OR] = 2.01; 95% CI = 1.53 to 2.63), and need for vasopressors (OR = 1.54; 95% CI = 1.13 to 2.12).

CONCLUSIONS

Use of a clinical screening tool in combination with early bedside POC lactates has moderate to good specificity but low sensitivity in adult ED patients with suspected sepsis. Elevated bedside lactate levels are associated with poor outcomes.

Nitroglycerin reverts clinical manifestations of poor peripheral perfusion in patients with circulatory shock

INTRODUCTION

Recent clinical studies have shown a relationship between abnormalities in peripheral perfusion and unfavorable outcome in patients with circulatory shock. Nitroglycerin is effective in restoring alterations in microcirculatory blood flow. The aim of this study was to investigate whether nitroglycerin could correct the parameters of abnormal peripheral circulation in resuscitated circulatory shock patients.

METHODS

This interventional study recruited patients who had circulatory shock and who persisted with abnormal peripheral perfusion despite normalization of global hemodynamic parameters. Nitroglycerin started at 2 mg/hour and doubled stepwise (4, 8, and 16 mg/hour) each 15 minutes until an improvement in peripheral perfusion was observed. Peripheral circulation parameters included capillary refill time (CRT), skin-temperature gradient (Tskin-diff), perfusion index (PI), and tissue oxygen saturation (StO2) during a reactive hyperemia test (RincStO2). Measurements were performed before, at the maximum dose, and after cessation of nitroglycerin infusion. Data were analyzed by using linear model for repeated measurements and are presented as mean (standard error).

RESULTS

Of the 15 patients included, four patients (27%) responded with an initial nitroglycerin dose of 2 mg/hour. In all patients, nitroglycerin infusion resulted in significant changes in CRT, Tskin-diff, and PI toward normal at the maximum dose of nitroglycerin: from 9.4 (0.6) seconds to 4.8 (0.3) seconds (P < 0.05), from 3.3 °C (0.7 °C) to 0.7 °C (0.6 °C) (P < 0.05), and from [log] -0.5% (0.2%) to 0.7% (0.1%) (P < 0.05), respectively. Similar changes in StO2 and RincStO2 were observed: from 75% (3.4%) to 84% (2.7%) (P < 0.05) and 1.9%/second (0.08%/second) to 2.8%/second (0.05%/second) (P < 0.05), respectively. The magnitude of changes in StO2 was more pronounced for StO2 of less than 75%: 11% versus 4%, respectively (P < 0.05).

CONCLUSIONS

Dose-dependent infusion of nitroglycerin reverted abnormal peripheral perfusion and poor tissue oxygenation in patients following circulatory shock resuscitation. Individual requirements of nitroglycerin dose to improve peripheral circulation vary between patients. A simple and fast physical examination of peripheral circulation at the bedside can be used to titrate nitroglycerin infusion.

Clinical monitoring of peripheral perfusion: there is more to learn

Irrespective of initiating factors, the peripheral circulation shows two general phases during the development and treatment of shock. Most published reports support earlier knowledge that the peripheral circulation is among the first to deteriorate and the last to be restored. With the advent of new and old techniques that allow us to continuously monitor peripheral perfusion, we may further shift our focus from pressure-based to flow-based resuscitation. The persisting challenge is the validation (effect on outcome parameters) of peripheral perfusion monitoring tools that can be simple and readily available worldwide.

Tissue oxygen saturation for the risk stratification of septic patients

PURPOSE

Peripheral tissue oxygen saturation (Sto2) has shown promise as an early indicator of tissue hypoperfusion and as a risk stratification tool in various forms of shock. The purpose of this study was to determine if Sto2 would predict admission to an intensive (ICU) or progressive care unit in patients with early signs of sepsis.

METHODS

In this prospective observational study, a rapid response team measured Sto2 levels in patients screening positive for sepsis. Using a logistic regression model, the value of Sto2 as a predictor for ICU admission within 72 hours of the initial assessment was determined.

RESULTS

The 31 (47%) of 66 patients who required ICU admission within 72 hours of evaluation had a significantly lower Sto2 value (median, 78% vs 81%; P = .05). All patients with Sto2 less than 70% required ICU admission. A 1-point increase in Sto2 was associated with a 7% decrease in the odds of requiring ICU admission, and the area under the curve for Sto2 was 0.64 (0.51-0.77, P = .01).

CONCLUSIONS

Low Sto2 levels in patients screening positive for sepsis are associated with an increased risk of ICU admission, but their reliability as a predictor is rather low. An Sto2 below 70% might be an interesting cutoff value for further study.

The peripheral perfusion index and transcutaneous oxygen challenge test are predictive of mortality in septic patients after resuscitation

Introduction

The peripheral perfusion index (PI) is a noninvasive numerical value of peripheral perfusion, and the transcutaneous oxygen challenge test (OCT) is defined as the degree of transcutaneous partial pressure of oxygen (PtcO₂) response to 1.0 FiO_2. The value of noninvasive monitoring peripheral perfusion to predict outcome remains to be established in septic patients after resuscitation. Moreover, the prognostic value of PI has not been investigated in septic patients.

Methods

Forty-six septic patients, who were receiving PiCCO-Plus cardiac output monitoring, were included in the study group. Twenty stable postoperative patients were studied as a control group. All the patients inspired 1.0 of FiO₂ for 10 minutes during the OCT. Global hemodynamic variables, traditional metabolic variables, PI and OCT related-variables were measured simultaneously at 24 hours after PiCCO catheter insertion. We obtained the 10min-OCT ((PtcO₂ after 10 minutes on inspired 1.0 oxygen) - (baseline PtcO₂)), and the oxygen challenge index ((10min-OCT)/(PaO₂ on inspired 1.0 oxygen - baseline PaO₂)) during the OCT.

Results

The PI was significantly correlated with baseline PtcO₂, 10min-OCT and oxygen challenge index (OCI) in all the patients. The control group had a higher baseline PtcO₂, 10min-OCT and PI than the septic shock group. In the sepsis group, the macro hemodynamic parameters and ScvO₂ showed no differences between survivors and nonsurvivors. The nonsurvivors had a significantly lower PI, 10min-OCT and OCI, and higher arterial lactate level. The PI, 10min-OCT and OCI predicted the ICU mortality with an accuracy that was similar to arterial lactate level. A PI <0.2 and a 10min-OCT <66mmHg were related to poor outcome after resuscitation.

Conclusions

The PI and OCT are predictive of mortality for septic patients after resuscitation. Further investigations are required to determine whether the correction of an impaired level of peripheral perfusion may improve the outcome of septic shock patients.

Does lactate measurement performed on admission predict clinical outcome on the intensive care unit? A concise systematic review

Background

There is a need for practical, efficient and effective prognostic markers for patients admitted to the intensive care unit (ICU) with sepsis, to identify patients at highest risk and guide and monitor treatment. Although many biomarkers and scoring systems have been advocated, none have yet achieved this elusive combination. Most ICUs already use blood lactate concentrations to monitor patients but the evidence base for this application is unclear.

Methods

A systematic review of the last five years of evidence of effectiveness of lactate measurement in prediction of outcome in ICUs was performed.

Results

It was found that there is a lack of high-quality evidence, and no specific studies of prognostic accuracy. d- or l-Lactate concentrations measured in plasma, serum, whole blood or colonic washings were raised at admission in almost all patient groups, and were higher in patient groups who had the worst outcomes (in-hospital mortality, sequential organ failure). However, there was significant overlap in individual concentrations measured in those who died within 28 days of admission, or who developed multiple organ failure, and those who did not. For serum l-lactate concentrations, no specific cut-off value capable of predicting in-hospital mortality or sequential organ failure could be recommended.

Conclusions

The evidence reviewed suggested that whole blood, plasma or serum lactate measurement could not provide specific prognostic information for individual patients. There may be a role for monitoring for normalization of serum d- or l-lactate concentrations during goal-directed therapy in the ICU but further good-quality studies are needed. Measurement of the d-lactate stereoisomer shows promise, such that further studies are warranted.

Consecutive Daily Measurements of Luminal Concentrations of Lactate in the Rectum in Septic Shock Patients

In a recent study we found no difference in the concentrations of luminal lactate in the rectum between nonsurvivors and survivors in early septic shock (<24 h). This study was initiated to investigate if there are any changes in the concentrations of luminal lactate in the rectum during the first 3 days of septic shock and possible differences between nonsurvivors and survivors. Methods. We studied 22 patients with septic shock in this observational study. Six to 24 h after the onset of septic shock the concentration of lactate in the rectal lumen was estimated by 4 h equilibrium dialysis (day 1). The rectal dialysis was repeated on day 2 and day 3. Results. The concentration of lactate in the rectal lumen did not change over the 3 days in neither nonsurvivors nor survivors. Rectal luminal and arterial lactate concentrations were not different. Conclusion. There was no change in the concentration of lactate in the rectal lumen over time in patients with septic shock. Also, there was no difference between nonsurvivors and survivors.

The relation of near-infrared spectroscopy with changes in peripheral circulation in critically ill patients

OBJECTIVE

We conducted this observational study to investigate tissue oxygen saturation during a vascular occlusion test in relationship with the condition of peripheral circulation and outcome in critically ill patients.

DESIGN

Prospective observational study.

SETTING

Multidisciplinary intensive care unit in a university hospital.

PATIENTS

Seventy-three critically ill adult patients admitted to the intensive care unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were followed every 24 hrs until day 3 after intensive care admission. Near-infrared spectroscopy was used to measure thenar tissue oxygen saturation, tissue oxygen saturation deoxygenation rate, and tissue oxygen saturation recovery rate after the vascular occlusion test. Measurements included heart rate, mean arterial pressure, forearm-to-fingertip skin-temperature gradient, and physical examination of peripheral perfusion with capillary refill time. Patients were stratified according to the condition of peripheral circulation (abnormal: forearm-to-fingertip skin-temperature gradient ≥4 and capillary refill time >4.5 secs). The outcome was defined based on the daily Sequential Organ Failure Assessment score and blood lactate levels. Upon intensive care unit admission, 35 (47.9%) patients had abnormal peripheral perfusion (forearm-to-fingertip skin-temperature gradient >4 or capillary refill time >4.5 secs). With the exception of the tissue oxygen saturation deoxygenation rate, tissue oxygen saturation baseline and tissue oxygen saturation recovery rate were statistically lower in patients who exhibited abnormal peripheral perfusion than in those with normal peripheral perfusion: 72 ± 9 vs. 81 ± 9; p = .001 and 1.9 ± 0.7 vs. 3.2 ± 0.9; p = .001, respectively. When a mixed-model analysis was performed over time for estimate (s) calculation, adjusted to the condition of disease, we did not find a significant clinical effect between vascular occlusion test-derived tissue oxygen saturation measurements (as response variables) and mean systemic hemodynamic variables (as independent variables): tissue oxygen saturation vs. heart rate: s (95% confidence interval) = 0.007 (-0.08; 0.09); tissue oxygen saturation vs. mean arterial pressure: s (95% confidence interval) = -0.02 (-0.12; 0.08); tissue oxygen saturation deoxygenation rate vs. heart rate: s (95% confidence interval) = 0.002 (-0.0004; 0.006); tissue oxygen saturation deoxygenation rate vs. mean arterial pressure: s (95% confidence interval) - 0.0007 (-0.003; 0.004); tissue oxygen saturation recovery rate vs. heart rate: s (95% confidence interval) = -0.009 (-0.02; -0.0015); tissue oxygen saturation recovery rate vs. mean arterial pressure: s (95% confidence interval) = 0.01 (0.002; 0.018). However, there was a strong association between tissue oxygen saturation baseline and tissue oxygen saturation recovery rate with abnormal peripheral perfusion: tissue oxygen saturation vs. abnormal peripheral perfusion: s (95% confidence interval) = -10.1 (-13.9; -6.2); tissue oxygen saturation recovery rate vs. abnormal peripheral perfusion: s (95% confidence interval) =-10.1 (-13.9; -6.2); tissue oxygen saturation recovery rate vs. abnormal peripheral perfusion: s (95% confidence interval) = -1.1 (-1.4; -0.81). Poor outcome was more closely related to abnormalities in peripheral perfusion than to tissue oxygen saturation-derived parameters.

CONCLUSIONS

We found that the condition of peripheral circulation in critically ill patients strongly influences tissue oxygen saturation resting values and the tissue oxygen saturation reoxygenation rate but not the tissue oxygen saturation deoxygenation rate. In addition, changes in near-infrared spectroscopy-derived variables were independent of condition of disease and were not accompanied by any major differences in systemic hemodynamic variables.

[Objectives of hemodynamic resuscitation]

Cardiovascular failure or shock, of any etiology, is characterized by ineffective perfusion of body tissues, inducing derangements in the balance between oxygen delivery and consumption. Impairment in oxygen availability on the cellular level causes a shift to anaerobic metabolism, with an increase in lactate and hydrogen ion production that leads to lactic acidosis. The degree of hyperlactatemia and metabolic acidosis will be directly correlated to the development of organ failure and poor outcome of the individuals. The amount of oxygen available at the tissues will depend fundamentally on an adequate level of perfusion pressure and oxygen delivery. The optimization of these two physiologic parameters can re-establish the balance between oxygen delivery and consumption on the cellular level, thus, restoring the metabolism to its aerobic paths. Monitoring variables such as lactate and oxygen venous saturations (either central or mixed) during the initial resuscitation of shock will be helpful to determine whether tissue hypoxia is still present or not. Recently, some new technologies have been developed in order to evaluate local perfusion and microcirculation, such as gastric tonometry, near-infrared spectroscopy and videomicroscopy. Although monitoring these regional parameters has demonstrated its prognostic value, there is a lack of evidence regarding to its usefulness during the resuscitation process. In conclusion, hemodynamic resuscitation is still based on the rapid achievement of adequate levels of perfusion pressure, and then on the modification of oxygen delivery variables, in order to restore physiologic values of ScvO(2)/SvO(2) and resolve lactic acidosis and/or hyperlactatemia.

Low tissue oxygen saturation at the end of early goal-directed therapy is associated with worse outcome in critically ill patients

Introduction

The prognostic value of continuous monitoring of tissue oxygen saturation (StO₂) during early goal-directed therapy of critically ill patients has not been investigated. We conducted this prospective study to test the hypothesis that the persistence of low StO₂ levels following intensive care admission is related to adverse outcome.

Methods

We followed 22 critically ill patients admitted with increased lactate levels (>3 mmol/l). Near-infrared spectroscopy (NIRS) was used to measure the thenar eminence StO₂ and the rate of StO₂ increase (R_incStO₂) after a vascular occlusion test. NIRS dynamic measurements were recorded at intensive care admission and each 2-hour interval during 8 hours of resuscitation. All repeated StO₂ measurements were further compared with Sequential Organ Failure Assessment (SOFA), Acute Physiology and Chronic Health Evaluation (APACHE) II and hemodynamic physiological variables: heart rate (HR), mean arterial pressure (MAP), central venous oxygen saturation (ScvO₂) and parameters of peripheral circulation (physical examination and peripheral flow index (PFI)).

Results

Twelve patients were admitted with low StO₂ levels (StO₂ <70%). The mean scores for SOFA and APACHE II scores were significantly higher in patients who persisted with low StO₂ levels (n = 10) than in those who exhibited normal StO₂ levels (n = 12) at 8 hours after the resuscitation period (P < 0.05; median (interquartile range): SOFA, 8 (7 to 11) vs. 5 (3 to 8); APACHE II, 32(24 to 33) vs. 19 (15 to 25)). There was no significant relationship between StO₂ and mean global hemodynamic variables (HR, P = 0.26; MAP, P = 0.51; ScvO₂, P = 0.11). However, there was a strong association between StO₂ with clinical abnormalities of peripheral perfusion (P = 0.004), PFI (P = 0.005) and R_incStO₂ (P = 0.002). The persistence of low StO₂ values was associated with a low percentage of lactate decrease (P < 0.05; median (interquartile range): 33% (12 to 43%) vs. 43% (30 to 54%)).

Conclusions

We found that patients who consistently exhibited low StO₂ levels following an initial resuscitation had significantly worse organ failure than did patients with normal StO₂ values, and found that StO₂ changes had no relationship with global hemodynamic variables.

Management of sepsis in patients with liver failure

PURPOSE OF REVIEW

Sepsis constitutes the most common cause of death in the ICU. Liver dysfunction is manifested among previously normal subjects with sepsis but even more so in populations with preexisting liver disease. Managing these patients is more challenging. We will review recent literature in sepsis and liver disease, and their bedside application.

RECENT FINDINGS

At the cellular-chemical level, studies showed that platelet aggregation and neutrophil activation occur before and are independent of microcirculatory changes which are apparent in all animal septic models. At the clinical level, early goal-directed therapy, euglycemia, low tidal volume ventilation, and early and appropriately dosed renal replacement therapy among others are all tools to improve sepsis survival. Acknowledgement of liver disease as an immunocompromised host, and identification and treatment of complications can positively change the outcome of sepsis in liver disease.

SUMMARY

Much has been advanced in the field of sepsis management. Understanding the pathophysiology of liver dysfunction and decompensation of a diseased liver incites questions for future research. Early goal-directed therapy, lactate clearance, glycemic control, low volume ventilation strategies, nutrition, adrenal insufficiency, renal dysfunction, hepatorenal syndrome prevention and treatment are some of the issues in the management of sepsis, with or without liver disease, that are relevant in this review.

Gastrointestinal perfusion in septic shock

Septic shock is characterised by vasodilation, myocardial depression and impaired microcirculatory blood flow, resulting in redistribution of regional blood flow. Animal and human studies have shown that gastrointestinal mucosal blood flow is impaired in septic shock. This is consistent with abnormalities found in many other microcirculatory vascular beds. Gastrointestinal mucosal microcirculatory perfusion deficits have been associated with gut injury and a decrease in gut barrier function, possibly causing augmentation of systemic inflammation and distant organ dysfunction. A range of techniques have been developed and used to quantify these gastrointestinal perfusion abnormalities. The following techniques have been used to study gastrointestinal perfusion in humans: tonometry, laser Doppler flowmetry, reflectance spectrophotometry, near-infrared spectroscopy, orthogonal polarisation spectral imaging, indocyanine green clearance, hepatic vein catheterisation and measurements of plasma D-lactate. Although these methods share the ability to predict outcome in septic shock patients, it is important to emphasise that the measurement results are not interchangeable. Different techniques measure different elements of gastrointestinal perfusion. Gastric tonometry is currently the most widely used technique because of its non-invasiveness and ease of use. Despite all the recent advances, the usefulness of gastrointestinal perfusion parameters in clinical decision-making is still limited. Treatment strategies specifically aimed at improving gastrointestinal perfuision have failed to actually correct mucosal perfusion abnormalities and hence not shown to improve important clinical endpoints. Current and future treatment strategies for septic shock should be tested for their effects on gastrointestinal perfusion; to further clarify its exact role in patient management, and to prevent therapies detrimental to gastrointestinal perfusion being implemented.

Importance of transesophageal echocardiography in the critically ill and injured patient

Echocardiography, particularly transesophageal echocardiography (TEE), is a vital diagnostic and monitoring imaging modality for the intensivist. The field of echocardiography spans different venues and pathologies, ranging from surface transthoracic echocardiography and portable hand-held echocardiography, to contrast echocardiography, stress echocardiography, and TEE, among others. Numerous investigations have proven the worth of echocardiography, especially TEE, in the critically ill and injured patient, changing lives with the identification of obvious and subtle cardiothoracic diseases. Because this powerful imaging tool is immediately available and portable, crucial delays in diagnosis are not commonplace; rather than echocardiography, TEE, specifically, should be (and is in some institutions) the standard of care and management in assisting the intensivist in diagnosis of a variety of maladies. The effect of TEE technology is quite formidable, and numerous investigations have borne this out. The therapeutic effect of TEE ranges from 10% to 69%, with the majority of investigations falling into the 60% to 65% range. The diagnostic yield of TEE is far greater, approaching 78%. This article will detail the importance of echocardiography, its efficacy, and its high-yield imaging capability, particularly when compared with other imaging modalities, even transthoracic echocardiography.

Hemodynamic monitoring in shock and implications for management. International Consensus Conference, Paris, France, 27-28 April 2006

OBJECTIVE

Shock is a severe syndrome resulting in multiple organ dysfunction and a high mortality rate. The goal of this consensus statement is to provide recommendations regarding the monitoring and management of the critically ill patient with shock.

METHODS

An international consensus conference was held in April 2006 to develop recommendations for hemodynamic monitoring and implications for management of patients with shock. Evidence-based recommendations were developed, after conferring with experts and reviewing the pertinent literature, by a jury of 11 persons representing five critical care societies.

DATA SYNTHESIS

A total of 17 recommendations were developed to provide guidance to intensive care physicians monitoring and caring for the patient with shock. Topics addressed were as follows: (1) What are the epidemiologic and pathophysiologic features of shock in the ICU? (2) Should we monitor preload and fluid responsiveness in shock? (3) How and when should we monitor stroke volume or cardiac output in shock? (4) What markers of the regional and micro-circulation can be monitored, and how can cellular function be assessed in shock? (5) What is the evidence for using hemodynamic monitoring to direct therapy in shock? One of the most important recommendations was that hypotension is not required to define shock, and as a result, importance is assigned to the presence of inadequate tissue perfusion on physical examination. Given the current evidence, the only bio-marker recommended for diagnosis or staging of shock is blood lactate. The jury also recommended against the routine use of (1) the pulmonary artery catheter in shock and (2) static preload measurements used alone to predict fluid responsiveness.

CONCLUSIONS

This consensus statement provides 17 different recommendations pertaining to the monitoring and caring of patients with shock. There were some important questions that could not be fully addressed using an evidence-based approach, and areas needing further research were identified.

Assessing liver function

PURPOSE OF REVIEW

This is a review on the techniques for assessing liver function in critically ill patients.

RECENT FINDINGS

Actually, there is no ideal real-time and bedside technique for assessing liver function in critically ill patients. Though not allowing to differentiate between liver blood flow and cell function, dynamic tests, that is indocyanine green plasma disappearance rate and lidocaine metabolism (monoethylglycinxylidide test), are superior, however, to static tests. Recently, the indocyanine green plasma disappearance rate, which nowadays can be measured reliably by a transcutaneous system in critically ill patients, was confirmed to correlate well with indocyanine green clearance. In general, the indocyanine green plasma disappearance rate is superior to bilirubin, which is still used as a marker of liver function, and comparable or even superior to complex intensive care scoring systems in terms of outcome prediction. Furthermore, indocyanine green plasma disappearance rate is more sensitive than serum enzyme tests for assessing liver dysfunction and early improvement in the indocyanine green plasma disappearance rate after onset of septic shock is associated with better outcome.

SUMMARY

Since no ideal tool is currently available, dynamic tests such as indocyanine green plasma disappearance rate and monoethylglycinxylidide test may be recommended for assessing liver function in critically ill patients. The indocyanine green plasma disappearance rate has the advantage, however, of being measurable noninvasively at the bedside and providing results within a few minutes.