The effect of increasing doses of norepinephrine on tissue oxygenation and microvascular flow in patients with septic shock*:

Relationships between blood pressure measurements and target organ damage: Data from the Korea women's chest pain registry

This study was performed to investigate the association between four BP measurements (systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP], and pulse pressure [PP]) and four TOD parameters (left ventricular mass index [LVMI], E/e', estimated glomerular filtration rate [eGFR], and obstructive coronary artery disease [CAD]). Data were obtained from a nation-wide registry, composed of 652 patients (471 women, 58.4 ± 10.5 years) with suspected CAD who underwent elective invasive coronary angiography (CAG). A total of 217 patients (33.2%) had obstructive CAD (≥50%). In multivariable analyses, E/e' was associated with SBP, MAP and PP, and CAD was associated with SBP and PP (P < 0.05 for each). All four BP measurements were not associated with LVMI and eGFR (P > 0.05 for each). In patients undergoing elective invasive CAG, SBP, and PP had stronger relationships with E/e' and CAD than DBP and MAP.

Hemodynamic support in the early phase of septic shock: a review of challenges and unanswered questions

Background

Improving sepsis support is one of the three pillars of a 2017 resolution according to the World Health Organization (WHO). Septic shock is indeed a burden issue in the intensive care units. Hemodynamic stabilization is a cornerstone element in the bundle of supportive treatments recommended in the Surviving Sepsis Campaign (SSC) consecutive biannual reports.

Main body

The “Pandera’s box” of septic shock hemodynamics is an eternal debate, however, with permanent contentious issues. Fluid resuscitation is a prerequisite intervention for sepsis rescue, but selection, modalities, dosage as well as duration are subject to discussion while too much fluid is associated with worsen outcome, vasopressors often need to be early introduced in addition, and catecholamines have long been recommended first in the management of septic shock. However, not all patients respond positively and controversy surrounding the efficacy-to-safety profile of catecholamines has come out. Preservation of the macrocirculation through a “best” mean arterial pressure target is the actual priority but is still contentious. Microcirculation recruitment is a novel goal to be achieved but is claiming more knowledge and monitoring standardization. Protection of the cardio-renal axis, which is prevalently injured during septic shock, is also an unavoidable objective. Several promising alternative or additive drug supporting avenues are emerging, trending toward catecholamine’s sparing or even “decatecholaminization.” Topics to be specifically addressed in this review are: (1) mean arterial pressure targeting, (2) fluid resuscitation, and (3) hemodynamic drug support.

Conclusion

Improving assessment and means for rescuing hemodynamics in early septic shock is still a work in progress. Indeed, the bigger the unresolved questions, the lower the quality of evidence.

Microcirculatory changes in children undergoing cardiac surgery: a prospective observational study

BACKGROUND

The effects of cardiac surgery on the microcirculation of children are unknown. The aim of this study was to assess the microcirculatory changes in children undergoing surgery for correction of congenital heart disease.

METHODS

We used a videomicroscope (Sidestream Dark Field, SDF) in a convenience sample of 24 children <five yr old. Total vascular density (TVD, vessels mm(-2)), microvascular flow index (MFI, arbitrary units), proportion of perfused small vessels (PPV, percentage), and perfused vessel density (PVD) were obtained after induction of anaesthesia (T1), at the end of the surgical procedure (T2), after intensive care unit (ICU) admission (T3), and at six h (T4) and 12h (T5) after ICU admission.

RESULTS

Microcirculatory variables did not significantly change over time. Haemodynamic parameters and microcirculatory variables were not correlated. In a subanalysis conducted for cyanotic (n=7) and acyanotic (n=17) children, repeated measures ANOVA showed a significant interaction between time and the presence of cyanosis for PPV (P=0.03), TVD (P=0.03), and PVD (P=0.03). Weak inverse correlations were found between storage time of transfused red blood cell (RBCs) and MFI at T3 (r=-0.63, P=0.01) and T4 (r=-0.53, P=0.03).

CONCLUSIONS

Microcirculatory variables have a different time-related trend in cyanotic and acyanotic children undergoing cardiac surgery. The storage time of transfused RBCs seems to negatively impact the microcirculation. Further and larger studies are warranted to prove the potential implications of this study.

Sepsis-induced acute kidney injury: A disease of the microcirculation

AKI is a common complication of sepsis and is significantly associated with mortality. Sepsis accounts for more than 50% of the cases of AKI, with a mortality rate of up to 40%. The pathogenesis of septic AKI is complex, but there is emerging evidence that, at least in the first 48 hours, the defects may be functional rather than structural in nature. For example, septic AKI is associated with an absence of histopathological changes, but with microvascular abnormalities and tubular stress. In this context, renal medullary hypoxia due to redistribution of intra-renal perfusion is emerging as a critical mediator of septic AKI. Clinically, vasopressor drugs remain the cornerstone of therapy for maintenance of blood pressure and organ perfusion. However, in septic AKI, there is insensitivity to vasopressors such as norepinephrine, leading to persistent hypotension and organ failure. Vasopressin, angiotensin II, and, paradoxically, α₂ -adrenergic receptor agonists (clonidine and dexmedetomidine) may be feasible adjunct therapies for catecholamine-resistant vasodilatory shock. In this review, we outline the recent progress made in understanding how these drugs may influence the renal microcirculation, which represents a crucial step toward developing better approaches for the circulatory management of patients with septic AKI.

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.

Shock subtypes by left ventricular ejection fraction following out-of-hospital cardiac arrest

Background

Post-resuscitation hemodynamic instability following out-of-hospital cardiac arrest (OHCA) may occur from myocardial dysfunction underlying cardiogenic shock and/or inflammation-mediated distributive shock. Distinguishing the predominant shock subtype with widely available clinical metrics may have prognostic and therapeutic value.

Methods

A two-hospital cohort was assembled of patients in shock following OHCA. Left ventricular ejection fraction (LVEF) was assessed via echocardiography or cardiac ventriculography within 1 day post arrest and used to delineate shock physiology. The study evaluated whether higher LVEF, indicating distributive-predominant shock physiology, was associated with neurocognitive outcome (primary endpoint), survival, and duration of multiple organ failures. The study also investigated whether volume resuscitation exhibited a subtype-specific association with outcome.

Results

Of 162 patients with post-resuscitation shock, 48% had normal LVEF (> 40%), consistent with distributive shock physiology. Higher LVEF was associated with less favorable neurocognitive outcome (OR 0.74, 95% CI 0.58–0.94 per 10% increase in LVEF; p = 0.01). Higher LVEF also was associated with worse survival (OR 0.81, 95% CI 0.67–0.97; p = 0.02) and fewer organ failure-free days (β = – 0.67, 95% CI – 1.28 to − 0.06; p = 0.03). Only 51% of patients received a volume challenge of at least 30 ml/kg body weight in the first 6 h post arrest, and the volume received did not differ by LVEF. Greater volume resuscitation in the first 6 h post arrest was associated with favorable neurocognitive outcome (OR 1.59, 95% CI 0.99–2.55 per liter; p = 0.03) and survival (OR 1.44, 95% CI 1.02–2.04; p = 0.02) among patients with normal LVEF but not low LVEF.

Conclusions

In post-resuscitation shock, higher LVEF—indicating distributive shock physiology—was associated with less favorable neurocognitive outcome, fewer days without organ failure, and higher mortality. Greater early volume resuscitation was associated with more favorable neurocognitive outcome and survival in patients with this shock subtype. Additional studies with repeated measures of complementary hemodynamic parameters are warranted to validate the clinical utility for subtyping post-resuscitation shock.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2078-x) contains supplementary material, which is available to authorized users.

A global perspective on vasoactive agents in shock

PURPOSE

We set out to summarize the current knowledge on vasoactive drugs and their use in the management of shock to inform physicians' practices.

METHODS

This is a narrative review by a multidisciplinary, multinational-from six continents-panel of experts including physicians, a pharmacist, trialists, and scientists.

RESULTS AND CONCLUSIONS

Vasoactive drugs are an essential part of shock management. Catecholamines are the most commonly used vasoactive agents in the intensive care unit, and among them norepinephrine is the first-line therapy in most clinical conditions. Inotropes are indicated when myocardial function is depressed and dobutamine remains the first-line therapy. Vasoactive drugs have a narrow therapeutic spectrum and expose the patients to potentially lethal complications. Thus, these agents require precise therapeutic targets, close monitoring with titration to the minimal efficacious dose and should be weaned as promptly as possible. Moreover, the use of vasoactive drugs in shock requires an individualized approach. Vasopressin and possibly angiotensin II may be useful owing to their norepinephrine-sparing effects.

Feasibility of optical coherence tomography angiography to assess changes in retinal microcirculation in ovine haemorrhagic shock

BACKGROUND

This study aimed to investigate the feasibility of optical coherence tomography angiography (OCT-A) for quantitative analysis of flow density to assess changes in retinal perfusion in an experimental model of haemorrhagic shock.

METHODS

Haemorrhagic shock was induced in five healthy, anaesthetized sheep by stepwise blood withdrawal of 3 × 10 ml∙kg- 1 body weight. OCT-A imaging of retinal perfusion was performed using an OCT device. Incident dark-field illumination microscopy videos were obtained for the evaluation of conjunctival microcirculation. Haemodynamic variables and flow density data in the OCT angiogram were analysed before and during progressive haemorrhage resulting in haemorrhagic shock as well as after fluid resuscitation with 10 ml∙kg- 1 body weight of balanced hydroxyethyl starch solution (6% HES 130/0.4). Videos of the conjunctival microcirculation were recorded at baseline, in haemorrhagic shock, and after resuscitation. Data are presented as median with interquartile range. Comparisons between time points were made using Friedman's test and the degree of correlation between two variables was expressed as Spearman's rank correlation coefficient.

RESULTS

Mean arterial pressure and cardiac index (CI) decreased and lactate concentration increased after induction of shock, and haemodynamics recovered after resuscitation. The flow density in the superficial retinal OCT angiogram decreased significantly after shock induction (baseline 44.7% (40.3; 50.5) vs haemorrhagic shock 34.5% (32.8; 40.4); P = 0.027) and recovered after fluid resuscitation (46.9% (41.7; 50.7) vs haemorrhagic shock; P = 0.027). The proportion of perfused vessels of the conjunctival microcirculation showed similar changes. The flow density measured using OCT-A correlated with the conjunctival microcirculation (perfused vessel density: Spearman's rank correlation coefficient ρ = 0.750, P = 0.001) and haemodynamic parameters (CI: ρ = 0.693, P < 0.001).

CONCLUSIONS

Retinal flow density, measured using OCT-A, significantly decreased in shock and recovered after fluid therapy in an experimental model of haemorrhagic shock. OCT-A is feasible to assess changes in retinal perfusion in haemorrhagic shock and fluid resuscitation.

Model for End-Stage Liver Disease Excluding INR (MELD-XI) score is associated with hemodynamic impairment and predicts mortality in critically ill patients

PURPOSE

We aimed (i) to evaluate Model for End-stage Liver Disease excluding INR (MELD-XI) score for prediction of mortality in a cohort of critically ill patients and (ii) to investigate associations of MELD-XI with microcirculation and (iii) to evaluate microcirculation for prediction of mortality in high-risk patients, e.g., with high MELD-XI scores.

METHODS

308 patients were included in our retrospective analysis, a subgroup of the multicenter micro-SOAP-study. Microcirculation was evaluated by Sidestream Dark Field (SDF) imaging. Evaluation of associations with mortality was done by logistic regression analysis, an optimal cut-off was calculated by means of the Youden Index. We divided the cohort in two sub-groups based on their MELD-XI score at the optimal cut-off (12 score points).

RESULTS

Patients with a MELD-XI > 12 points were of similar age (60 ± 1 years vs 62 ± 2 years; p = 0.32), but clinically sicker as mirrored by higher APACHE II scores (20 ± 1 vs 16 ± 1; p < 0.001). In the MELD-XI > 12 cohort in-hospital mortality was significantly higher compared to the MELD ≤ 12 group (48% vs 24%%; HR 2.98 95%CI 1.76-5.04; p = 0.003) and MELD-XI score was associated with mortality even after correction for relevant clinical confounders (HR 1.04 95%CI 1.01-1.07; p = 0.004) There were no associations between MELD-XI and parameters of microvascular perfusion.

CONCLUSIONS

MELD-XI is associated with in-hospital mortality and constitutes a useful tool for risk stratification in intensive care medicine. Interestingly, there were no associations between MELD-XI and microcirculation. Possibly parameters of the microcirculation present an online tool of hemodynamic assessment while MELD-XI presents an assessment of already established organ failure.

Monitoring microcirculation in critical illness

PURPOSE OF REVIEW

Critical illness includes a wide range of conditions from sepsis to high-risk surgery. All these diseases are characterized by reduced tissue oxygenation. Macrohemodynamic parameters may be corrected by fluids and/or vasoactive compounds; however, the microcirculation and its tissues may be damaged and remain hypoperfused. An evaluation of microcirculation may enable more physiologically based approaches for understanding the pathogenesis, diagnosis, and treatment of critically ill patients.

RECENT FINDINGS

Microcirculation plays a pivotal role in delivering oxygen to the cells and maintains tissue perfusion. Negative results of several studies, based on conventional hemodynamic resuscitation procedures to achieve organ perfusion and decrease morbidity and mortality following conditions of septic shock and other cardiovascular compromise, have highlighted the need to monitor microcirculation. The loss of hemodynamic coherence between the macrocirculation and microcirculation, wherein improvement of hemodynamic variables of the systemic circulation does not cause a parallel improvement of microcirculatory perfusion and oxygenation of the essential organ systems, may explain why these studies have failed.

SUMMARY

Critical illness is usually accompanied by abnormalities in microcirculation and tissue hypoxia. Direct monitoring of sublingual microcirculation using hand-held microscopy may provide a more physiological approach. Evaluating the coherence between macrocirculation and microcirculation in response to therapy seems to be essential in evaluating the efficacy of therapeutic interventions.

Vasodilators in Septic Shock Resuscitation: A Clinical Perspective

Microcirculatory abnormalities have been shown to be frequent in patients with septic shock despite "normalization" of systemic hemodynamics. Several studies have explored the impact of vasodilator therapy (prostacyclin, inhaled nitric oxide, topic acetylcholine, and nitroglycerin) on microcirculation and tissue perfusion, with contradictory findings.In this narrative review, we briefly present the pathophysiological aspects of microcirculatory dysfunction, and depict the evidence supporting the use of vasodilators and other therapeutic interventions (fluid administration, blood transfusion, vasopressors, and dobutamine) aiming to improve the microcirculatory flow in septic shock patients.

Hyperthermic intrathoracic chemotherapy after extended pleurectomy and decortication for malignant pleura mesothelioma: an observational study on outcome and microcirculatory changes

Background

In the treatment of malignant pleural mesothelioma the Hyperthermic Intra THOracic Chemotherapy (HITHOC) can improve the efficacy of pleurectomy and decortication with a local cytotoxic effect. However its biological impact in patient's hemodynamic and microcirculatory changes were rarely investigated. Aim of this study is to describe our experience with HITHOC after pleurectomy and decortication evaluating the role of sublingual video-microscopy in assessing the microcirculatory changes in the perioperative period.

Methods

This is a prospective and observational study concerning 10 consecutive patients undergoing extended P/D followed by HITHOC. These patients underwent sublingual microcirculatory monitoring, which was adopted as a routine procedure since 2012. Haemodynamic parameters were collected at eight consecutive times: the day before surgery (T1), induction of anaesthesia (T2), surgical phase before HITHOC beginning (T3), 5 and 30 minutes after HITHOC start (T4 and T5, respectively), 5 minutes from HITHOC end (T6), after the admission in ICU (T7), at discharge from the ICU (T8). Cardiac output (CO) was calculated with MostCare. Systemic vascular resistance (SVR), oxygen delivery (DO₂), and oxygen extraction rate (O₂ER) were calculated using standard formulas. Arterial blood pressure and central venous pressure (CVP) were obtained with standard arterial and venous catheters. At the same times we assessed the sublingual microcirculation with Sidestream Dark Field technique.

Results

Hemodynamic and microcirculatory data were collected in 10 patients, 8 male and 2 females (mean age 68.6±9.0, and body surface area of 1.9±0.1 m²). All patients had arterial hypertension, and one patient had diabetes. The mean arterial pressure significantly decreased at T2, with respect to T1 (P=0.05). CO, CVP, DO₂, O₂ER, and ScvO₂, did not change significantly over the time. All patients needed infusion of noradrenalin from T4 to T6. TVD significantly decreased from T1 to T3, T5, and T8. Similarly, PVD significantly decreased from T1 to T3 and T8, and MFI from T1 to T6 and T8. PPV and HI did not change over the study period. No correlation was found between hemodynamic parameters (MAP, CO, CVP, DO₂, O₂ER, ScvO₂) and microcirculatory data (TVD, PVD, PPV, MFI, HI), at any time of the study.

Conclusions

In patients who receive HITHOC the fluid load can reduce the microvascular impairment restoring the normal tissue perfusion. This process takes days but is most evident in the first 72 h. The use of colloid and blood transfusion is much more effective in restoring microcirculation and reducing tissue damaging.

Photonic monitoring of treatment during infection and sepsis: development of new detection strategies and potential clinical applications

Despite the strong decline in the infection-associated mortality since the development of the first antibiotics, infectious diseases are still a major cause of death in the world. With the rising number of antibiotic-resistant pathogens, the incidence of deaths caused by infections may increase strongly in the future. Survival rates in sepsis, which occurs when body response to infections becomes uncontrolled, are still very poor if an adequate therapy is not initiated immediately. Therefore, approaches to monitor the treatment efficacy are crucially needed to adapt therapeutic strategies according to the patient's response. An increasing number of photonic technologies are being considered for diagnostic purpose and monitoring of therapeutic response; however many of these strategies have not been introduced into clinical routine, yet. Here, we review photonic strategies to monitor response to treatment in patients with infectious disease, sepsis, and septic shock. We also include some selected approaches for the development of new drugs in animal models as well as new monitoring strategies which might be applicable to evaluate treatment response in humans in the future. Figure Label-free probing of blood properties using photonics.

Microcirculation improvement after short-term infusion of vasopressin in septic shock is dependent on noradrenaline

OBJECTIVES

To assess the impact of vasopressin on the microcirculation and to develop a predictive model to estimate the probability of microcirculatory recruitment in patients with septic shock.

METHODS

This prospective interventional study included patients with septic shock receiving noradrenaline for less than 48 hours. We infused vasopressin at 0.04 U/min for one hour. Hemodynamic measurements, including sidestream dark-field imaging, were obtained immediately before vasopressin infusion, 1 hour after vasopressin infusion and 1 hour after vasopressin withdrawal. We defined patients with more than a 10% increase in total vascular density and perfused vascular density as responders. ClinicalTrials.gov: NCT02053675.

RESULTS

Eighteen patients were included, and nine (50%) showed improved microcirculation after infusion of vasopressin. The noradrenaline dose was significantly reduced after vasopressin (p=0.001) and was higher both at baseline and during vasopressin infusion in the responders than in the non-responders. The strongest predictor for a favorable microcirculatory response was the dose of noradrenaline at baseline (OR=4.5; 95% CI: 1.2-17.0; p=0.027). For patients using a noradrenaline dose higher than 0.38 mcg/kg/min, the probability that microcirculatory perfusion would be improved with vasopressin was 53% (sensitivity 78%, specificity 77%).

CONCLUSIONS

In patients with septic shock for no longer than 48 h, administration of vasopressin is likely to result in an improvement in microcirculation when the baseline noradrenaline dose is higher than 0.38 mcg/kg/min.

Discontinuation of Vasopressin Before Norepinephrine in the Recovery Phase of Septic Shock

BACKGROUND

Guidance for the discontinuation of vasopressors in the recovery phase of septic shock is limited. Norepinephrine is more easily titrated; however, septic shock is a vasopressin deficient state, which exogenous vasopressin endeavors to resolve. Discontinuation of vasopressin before norepinephrine may result in clinically significant hypotension.

METHODS

This retrospective, cohort study compared discontinuation of norepinephrine and vasopressin in medically, critically ill patients in the recovery phase of septic shock from May 2014 to June 2016. Difference in clinically significant hypotension after norepinephrine or vasopressin discontinuation was evaluated with χ² test. Linear regression was performed, examining the effect of agent discontinuation on clinically significant hypotension. Baseline variables were examined for a bivariate relationship with clinically significant hypotension; those with P < .2 were included in the model.

RESULTS

Vasopressin was discontinued first or last in 62 and 92 patients, respectively. Sequential Organ Failure Assessment scores at 72 hours (7.9 vs 7.6, P = .679) were similar. In unadjusted analysis, when vasopressin was discontinued first, more clinically significant hypotension developed (10.9% vs 67.8%, P < .001). There was no difference in intensive care unit (174 vs 216 hours, P = .178) or hospital duration (470 vs 473 hours, P = .977). In adjusted analyses, discontinuing vasopressin first was associated with increased clinically significant hypotension (odds ratio [OR]: 13.837, 95% confidence interval [CI]: 3.403-56.250, P < .001) but not in-hospital (OR: 0.659, 95% CI: 0.204-2.137, P = .488) or 28-day mortality (OR: 0.215, 95% CI: 0.037-1.246, P = .086).

CONCLUSION

Adult patients receiving norepinephrine and vasopressin in the resolving phase of septic shock may be less likely to develop clinically significant hypotension if vasopressin is the final vasopressor discontinued.

Haemodynamic coherence in perioperative setting

Over the last decade, there has been an increased interest in the use of goal-directed therapy (GDT) in patients undergoing high-risk surgery, and various haemodynamic monitoring tools have been developed to guide perioperative care. Both the complexity of the patient and surgical procedure need to be considered when deciding whether GDT will be beneficial. Ensuring optimum tissue perfusion is paramount in the perioperative period and relies on the coherence between both macrovascular and microvascular circulations. Although global haemodynamic parameters may be optimised with the use of GDT, microvascular impairment can still persist. This review will provide an overview of both haemodynamic optimisation and microvascular assessment in the perioperative period.

Hemodynamic coherence in sepsis

Microvascular alterations are a hallmark of sepsis and play a crucial role in its pathophysiology. Such alterations are the result of overwhelming inflammation, which negatively affects all the components of the microcirculation. As the severity of microvascular alterations is associated with organ dysfunction and mortality, several strategies have been tested for improving microcirculation. Nevertheless, they are mainly based on the conventional manipulation of systemic hemodynamics to increase the total flow to the organs and tissues. Other therapeutic interventions are still being investigated. In this review, we discuss the pathophysiology of septic microcirculatory dysfunction and its implications for possible treatments.

The vulnerable microcirculation in the critically ill pediatric patient

In neonates, cardiovascular system development does not stop after the transition from intra-uterine to extra-uterine life and is not limited to the macrocirculation. The microcirculation (MC), which is essential for oxygen, nutrient, and drug delivery to tissues and cells, also develops. Developmental changes in the microcirculatory structure continue to occur during the initial weeks of life in healthy neonates. The physiologic hallmarks of neonates and developing children make them particularly vulnerable during critical illness; however, the cardiovascular monitoring possibilities are limited compared with critically ill adult patients. Therefore, the development of non-invasive methods for monitoring the MC is necessary in pediatric critical care for early identification of impending deterioration and to enable the initiation and titration of therapy to ensure cell survival. To date, the MC may be non-invasively monitored at the bedside using hand-held videomicroscopy, which provides useful information regarding the microcirculation. There is an increasing number of studies on the MC in neonates and pediatric patients; however, additional steps are necessary to transition MC monitoring from bench to bedside. The recently introduced concept of hemodynamic coherence describes the relationship between changes in the MC and macrocirculation. The loss of hemodynamic coherence may result in a depressed MC despite an improvement in the macrocirculation, which represents a condition associated with adverse outcomes. In the pediatric intensive care unit, the concept of hemodynamic coherence may function as a framework to develop microcirculatory measurements towards implementation in daily clinical practice.

Association of Microcirculation, Macrocirculation, and Severity of Illness in Septic Shock: A Prospective Observational Study to Identify Microcirculatory Targets Potentially Suitable for Guidance of Hemodynamic Therapy

PURPOSE

Clinically unapparent microcirculatory impairment is common and has a negative impact on septic shock, but specific therapy is not established so far. This prospective observational study aimed at identifying candidate parameters for microcirculatory-guided hemodynamic therapy. ClinicalTrials.gov : NCT01530932.

MATERIALS AND METHODS

Microcirculatory flow and postcapillary venous oxygen saturation were detected during vaso-occlusive testing (VOT) on days 1 (T0), 2 (T24), and 4 (T72) in 20 patients with septic shock at a surgical intensive care unit using a laser Doppler spectrophotometry system (O2C).

RESULTS

Reperfusional maximal venous capillary oxygen saturation (SvcO₂max) showed negative correlations with Simplified Acute Physiology Score II (SAPSII)/Sequential Organ Failure Assessment (SOFA) score, norepinephrine dosage, and lactate concentration and showed positive correlations with cardiac index (CI). At T24 and T72, SvcO₂max was also inversely linked to fluid balance. With respect to any predictive value, SvcO₂max and CI determined on day 1 (T0) were negatively correlated with SAPS II/SOFA on day 4 (T72). Moreover, SvcO₂max measured on day 1 or day 2 was negatively correlated with cumulated fluid balance on day 4 ( r= -.472, P < .05 and r = -.829, P < .001). By contrast, CI neither on day 1 nor on day 2 was correlated with cumulated fluid balance on day 4 ( r = -.343, P = .17 and r = -.365, P = .15).

CONCLUSION

In patients with septic shock, microcirculatory reserve as assessed by SvcO₂max following VOT was impaired and negatively correlated with severity of illness and fluid balance. In contrast to CI, SvcO₂max determined on day 1 or day 2 was significantly negatively correlated with cumulative fluid balance on day 4. Therefore, early microcirculatory measurement of SvcO₂max might be superior to CI in guidance of sepsis therapy to avoid fluid overload. This has to be addressed in future clinical studies.

Hemodynamic management of septic shock: is it time for "individualized goal-directed hemodynamic therapy" and for specifically targeting the microcirculation?

Septic shock is a life-threatening condition in both critically ill medical patients and surgical patients during the perioperative phase. In septic shock, specific alterations in global cardiovascular dynamics (i.e., the macrocirculation) and in the microcirculatory blood flow (i.e., the microcirculation) have been described. However, the presence and degree of microcirculatory failure are in part independent from systemic macrohemodynamic variables. Macrocirculatory and microcirculatory failure can independently induce organ dysfunction. We review current diagnostic and therapeutic approaches for the assessment and optimization of both the macrocirculation and the microcirculation in septic shock. There are various technologies for the determination of macrocirculatory hemodynamic variables. We discuss the data on early goal-directed therapy for the resuscitation of the macrocirculation. In addition, we describe the concept of "individualized goal-directed hemodynamic therapy." Technologies to assess the local microcirculation are also available. However, adequate resuscitation goals for the optimization of the microcirculation still need to be defined. At present, we are not ready to specifically monitor and target the microcirculation in clinical routine outside studies. In the future, concepts for an integrative approach for individualized hemodynamic management of the macrocirculation and in parallel the microcirculation might constitute a huge opportunity to define additional resuscitation end points in septic shock.

Intrarenal and urinary oxygenation during norepinephrine resuscitation in ovine septic acute kidney injury

Norepinephrine is the principal vasopressor used to restore blood pressure in sepsis, but its effects on intrarenal oxygenation are unknown. To clarify this, we examined renal cortical, medullary, and urinary oxygenation in ovine septic acute kidney injury and the response to resuscitation with norepinephrine. A renal artery flow probe and fiberoptic probes were placed in the cortex and medulla of sheep to measure tissue perfusion and oxygenation. A probe in the bladder catheter measured urinary oxygenation. Sepsis was induced in conscious sheep by infusion of Escherichia coli for 32 hours. At 24 to 30 hours of sepsis, either norepinephrine, to restore mean arterial pressure to preseptic levels or vehicle-saline was infused (8 sheep per group). Septic acute kidney injury was characterized by a reduction in blood pressure of ∼12 mm Hg, renal hyperperfusion, and oliguria. Sepsis reduced medullary perfusion (from an average of 1289 to 628 blood perfusion units), medullary oxygenation (from 32 to 16 mm Hg), and urinary oxygenation (from 36 to 24 mm Hg). Restoring blood pressure with norepinephrine further reduced medullary perfusion to an average of 331 blood perfusion units, medullary oxygenation to 8 mm Hg and urinary oxygenation to 18 mm Hg. Cortical perfusion and oxygenation were preserved. Thus, renal medullary hypoxia caused by intrarenal blood flow redistribution may contribute to the development of septic acute kidney injury, and resuscitation of blood pressure with norepinephrine exacerbates medullary hypoxia. The parallel changes in medullary and urinary oxygenation suggest that urinary oxygenation may be a useful real-time biomarker for risk of acute kidney injury.

Observational study of the effects of traumatic injury, haemorrhagic shock and resuscitation on the microcirculation: a protocol for the MICROSHOCK study

INTRODUCTION

The microcirculation is the physiological site of oxygen and substrate exchange. Its effectiveness during circulatory shock is vital for the perfusion of tissues, and has a bearing on subsequent organ function and prognosis. Microcirculatory dysfunction following traumatic haemorrhagic shock (THS) has been understudied compared with other pathologies such as sepsis. The aim of the MICROSHOCK study is to investigate changes seen in the microcirculation of patients following THS, and to assess its response to resuscitation. A greater understanding of the behaviour and mechanisms of microcirculatory dysfunction in this context may direct future avenues of goal-directed resuscitation for these patients.

METHODS AND ANALYSIS

This multicentre prospective longitudinal observational study includes patients who present as an emergency with THS. Microcirculatory parameters are recorded using sublingual incident dark field microscopy alongside measurements of global flow (oesophageal Doppler and transthoracic echocardiography). Patients are enrolled into the study as soon as feasible after they arrive in hospital, and then at subsequent daily time points. Blood samples are taken for investigation into the mechanisms of microcirculatory dysfunction. Sequential Organ Failure Assessment scores will be analysed with microcirculatory parameters to determine whether they correlate with greater fidelity than more conventional, global circulatory parameters.

ETHICS AND DISSEMINATION

Research Ethics Committee approval has been granted for this study (Reference: 14/YH/0078). Owing to the nature of THS, capacity for informed consent will be absent on patient enrolment. This will be addressed according to the Mental Health Capacity Act 2005. The physician in charge of the patient's care (nominated consultee) may consent on behalf of the patient. Consent will also be sought from a personal consultee (close relative or friend). After capacity is regained, the participant will be asked for their consent. Results will be submitted for publication in peer-reviewed journal format and presented at relevant academic meetings.

TRIAL REGISTRATION NUMBER

NCT02111109; Pre-results.

What is microcirculatory shock?

PURPOSE OF REVIEW

Microcirculatory shock is a condition defined by the presence of tissue hypoperfusion despite the normalization of systemic and regional blood flow. In this article, we discuss the characteristics of the microcirculation in septic shock, the main form of microcirculatory shock, along with its interaction with systemic hemodynamics, and the response to different therapies.

RECENT FINDINGS

In septic shock, microcirculatory abnormalities are common, and more severe in nonsurvivors. In addition, the microcirculation shows a behavior that is frequently dissociated from that of systemic hemodynamics. Therefore, microcirculatory alterations may persist despite correction of systemic hemodynamic variables. Sublingual and intestinal microcirculation might also display divergent behaviors. Moreover, microvascular alterations may improve in response to hemodynamic resuscitation, but the response might depend on the underlying microcirculatory alterations. Particularly, the response to fluids seems to be related to both its basal state and the magnitude of the increase in cardiac output.

SUMMARY

The optimal treatment of microcirculatory shock might require monitoring and therapeutic goals targeted on the microcirculation, more than in systemic variables. The clinical benefits of this approach should be demonstrated in clinical trials.

Hemodynamic coherence and the rationale for monitoring the microcirculation

This article presents a personal viewpoint of the shortcoming of conventional hemodynamic resuscitation procedures in achieving organ perfusion and tissue oxygenation following conditions of shock and cardiovascular compromise, and why it is important to monitor the microcirculation in such conditions. The article emphasizes that if resuscitation procedures are based on the correction of systemic variables, there must be coherence between the macrocirculation and microcirculation if systemic hemodynamic-driven resuscitation procedures are to be effective in correcting organ perfusion and oxygenation. However, in conditions of inflammation and infection, which often accompany states of shock, vascular regulation and compensatory mechanisms needed to sustain hemodynamic coherence are lost, and the regional circulation and microcirculation remain in shock. We identify four types of microcirculatory alterations underlying the loss of hemodynamic coherence: type 1, heterogeneous microcirculatory flow; type 2, reduced capillary density induced by hemodilution and anemia; type 3, microcirculatory flow reduction caused by vasoconstriction or tamponade; and type 4, tissue edema. These microcirculatory alterations can be observed at the bedside using direct visualization of the sublingual microcirculation with hand-held vital microscopes. Each of these alterations results in oxygen delivery limitation to the tissue cells despite the presence of normalized systemic hemodynamic variables. Based on these concepts, we propose how to optimize the volume of fluid to maximize the oxygen-carrying capacity of the microcirculation to transport oxygen to the tissues.

β1-Adrenergic Inhibition Improves Cardiac and Vascular Function in Experimental Septic Shock

OBJECTIVE

Preliminary experimental data suggest that selective β1-blockers may improve ex vivo cardiac function in animal sepsis. Currently, the effects of esmolol on in vivo cardiac function and on vascular function are unknown. The present study was designed to examine the effects of the β1-selective blocker esmolol on myocardial and vascular function in peritonitis-induced septic rats and to explore the inflammatory pathways involved in this process.

DESIGN

Randomized animal study.

SETTING

University research laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Four hours after cecal ligation and puncture, Wistar rats were randomly allocated to the following groups: control, esmolol, norepinephrine (started at 18 hr after the surgery), and esmolol (started at 4 hr after the surgery) + norepinephrine (started at 18 hr after the surgery). Assessment at 18 hours after surgery was focused on cardiac contractility and vascular ex vivo function. Cardiac and vascular protein expressions of nuclear factor κB and endothelial nitric oxide synthase/Akt/inducible nitric oxide synthase pathways were assessed by Western blotting.

MEASUREMENTS AND MAIN RESULTS

When compared with sham-operated animals, cecal ligation and puncture animals developed hypotension, cardiac depression, and vascular hyporesponsiveness to vasopressor treatment. Esmolol infusion increased cardiac contractility and restored mesenteric vasoreactivity. This effect was associated with a decrease in nuclear factor κB activation, an increase in Akt and endothelial nitric oxide synthase phosphorylation, and a decrease in inducible nitric oxide synthase expression both at the cardiac and vessel level. Esmolol infusion was also associated with an up-regulation in α1-vascular adrenoreceptors.

CONCLUSION

Adjunction of selective β1-blockade to standard septic shock management enhances intrinsic cardiac contractility and vascular responsiveness to catecholamines. These protective cardiovascular effects are likely predominantly attributed to the anti-inflammatory effect of esmolol.

A rational approach to fluid therapy in sepsis

Aggressive fluid resuscitation to achieve a central venous pressure (CVP) greater than 8 mm Hg has been promoted as the standard of care, in the management of patients with severe sepsis and septic shock. However recent clinical trials have demonstrated that this approach does not improve the outcome of patients with severe sepsis and septic shock. Pathophysiologically, sepsis is characterized by vasoplegia with loss of arterial tone, venodilation with sequestration of blood in the unstressed blood compartment and changes in ventricular function with reduced compliance and reduced preload responsiveness. These data suggest that sepsis is primarily not a volume-depleted state and recent evidence demonstrates that most septic patients are poorly responsive to fluids. Furthermore, almost all of the administered fluid is sequestered in the tissues, resulting in severe oedema in vital organs and, thereby, increasing the risk of organ dysfunction. These data suggest that a physiologic, haemodynamically guided conservative approach to fluid therapy in patients with sepsis would be prudent and would likely reduce the morbidity and improve the outcome of this disease.

Early goal-directed resuscitation of patients with septic shock: current evidence and future directions

Severe sepsis and septic shock are among the leading causes of mortality in the intensive care unit. Over a decade ago, early goal-directed therapy (EGDT) emerged as a novel approach for reducing sepsis mortality and was incorporated into guidelines published by the international Surviving Sepsis Campaign. In addition to requiring early detection of sepsis and prompt initiation of antibiotics, the EGDT protocol requires invasive patient monitoring to guide resuscitation with intravenous fluids, vasopressors, red cell transfusions, and inotropes. The effect of these measures on patient outcomes, however, remains controversial. Recently, three large randomized trials were undertaken to re-examine the effect of EGDT on morbidity and mortality: the ProCESS trial in the United States, the ARISE trial in Australia and New Zealand, and the ProMISe trial in England. These trials showed that EGDT did not significantly decrease mortality in patients with septic shock compared with usual care. In particular, whereas early administration of antibiotics appeared to increase survival, tailoring resuscitation to static measurements of central venous pressure and central venous oxygen saturation did not confer survival benefit to most patients. In the following review, we examine these findings as well as other evidence from recent randomized trials of goal-directed resuscitation. We also discuss future areas of research and emerging paradigms in sepsis trials.

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.

Current concepts on hemodynamic support and therapy in septic shock

Severe sepsis and septic shock represent a major healthcare challenge. Much of the improvement in mortality associated with septic shock is related to early recognition combined with timely fluid resuscitation and adequate antibiotics administration. The main goals of septic shock resuscitation include intravascular replenishment, maintenance of adequate perfusion pressure and oxygen delivery to tissues. To achieve those goals, fluid responsiveness evaluation and complementary interventions - i.e. vasopressors, inotropes and blood transfusion - may be necessary. This article is a literature review of the available evidence on the initial hemodynamic support of the septic shock patients presenting to the emergency room or to the intensive care unit and the main interventions available to reach those targets, focusing on fluid and vasopressor therapy, blood transfusion and inotrope administration.

Arterial blood pressure targets in septic shock: is it time to move to an individualized approach?

Xu and colleagues evaluated the impact of increasing mean arterial blood pressure levels through norepinephrine administration on systemic hemodynamics, tissue perfusion, and sublingual microcirculation of septic shock patients with chronic hypertension. The authors concluded that, although increasing arterial blood pressure improved sublingual microcirculation parameters, no concomitant improvement in systemic tissue perfusion indicators was found. Here, we discuss why resuscitation targets may need to be individualized, taking into account the patient’s baseline condition, and present directions for future research in this field.

Accessing to arteriovenous blood flow dynamics response using combined laser speckle contrast imaging and skin optical clearing

Laser speckle contrast imaging (LSCI) shows a great potential for monitoring blood flow, but the spatial resolution suffers from the scattering of tissue. Here, we demonstrate the capability of a combination method of LSCI and skin optical clearing to describe in detail the dynamic response of cutaneous vasculature to vasoactive noradrenaline injection. Moreover, the superior resolution, contrast and sensitivity make it possible to rebuild arteries-veins separation and quantitatively assess the blood flow dynamical changes in terms of flow velocity and vascular diameter at single artery or vein level.

Effects of early hemodynamic resuscitation on left ventricular performance and microcirculatory function during endotoxic shock

Background

Microcirculation and macrohemodynamics are severely compromised during septic shock. However, the relationship between these two compartments needs to be further investigated. We hypothesized that early resuscitation restores left ventricular (LV) performance and microcirculatory function but fails to prevent metabolic disorders. We studied the effects of an early resuscitation protocol (ERP) on LV pressure/volume loops-derived parameters, sublingual microcirculation, and metabolic alterations during endotoxic shock.

Methods

Twenty-five pigs were randomized into three groups: LPS group: Escherichia coli lipopolysaccharide (LPS); ERP group: LPS + ERP based on volume expansion, dobutamine, and noradrenaline infusion; Sham group. LV pressure/volume-derived parameters, systemic hemodynamics, sublingual microcirculation, and metabolic profile were assessed at baseline and after completing the resuscitation protocol.

Results

LPS significantly decreased LV end-diastolic volume, myocardial contractility, stroke work, and cardiac index (CI). Early resuscitation preserved preload, and myocardial contractility, increased CI and heart rate (p < .05). LPS severely diminished sublingual microvascular flow index (MFI), perfused vascular density (PVD), and the proportion of perfused vessels (PPV), while increased the heterogeneity flow index (HFI) (p < .05). Despite MFI was relatively preserved, MVD, PVD, and HFI were significantly impaired after resuscitation (p < .05). The macro- and microcirculatory changes were associated with increased lactic acidosis and mixed venous O₂ saturation when compared to baseline values (p < .05). The scatter plot between mean arterial pressure (MAP) and MFI showed a biphasic relationship, suggesting that the values were within the limits of microvascular autoregulation when MAP was above 71 ± 6 mm Hg (R² = 0.63).

Conclusions

Early hemodynamic resuscitation was effective to restore macrohemodynamia and myocardial contractility. Despite MAP and MFI were relatively preserved, the persistent microvascular dysfunction could explain metabolic disorders. The relationship between micro- and systemic hemodynamia and their impact on cellular function and metabolism needs to be further studied during endotoxic shock.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-015-0049-y) contains supplementary material, which is available to authorized users.

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.

A high mean arterial pressure target is associated with improved microcirculation in septic shock patients with previous hypertension: a prospective open label study

Introduction

The effect of mean arterial pressure titration to a higher level on microcirculation in septic shock patients with previous hypertension remains unknown. Our goal is to assess the effect of mean arterial pressure titration to a higher level on microcirculation in hypertensive septic shock patients.

Methods

This is a single-center, open-label study. Hypertensive patients with septic shock for less than 24 hours after adequate fluid resuscitation and requiring norepinephrine to maintain a mean arterial pressure of 65 mmHg were enrolled. Mean arterial pressure was then titrated by norepinephrine from 65 mmHg to the normal level of the patient. In addition to hemodynamic variables, sublingual microcirculation was evaluated by sidestream dark field imaging.

Results

Nineteen patients were enrolled in the study. Increasing mean arterial pressure from 65 mmHg to normal levels was associated with increased central venous pressure (from 11 ± 4 to 13 ± 4 mmHg, P = 0.002), cardiac output (from 5.4 ± 1.4 to 6.4 ± 2.1 l/minute, P = 0.001), and central venous oxygen saturation (from 81 ± 7 to 83 ± 7%, P = 0.001). There were significant increases in small perfused vessel density (from 10.96 ± 2.98 to 11.99 ± 2.55 vessels/mm², P = 0.009), proportion of small perfused vessels (from 85 ± 18 to 92 ± 14%, P = 0.002), and small microvascular flow index (from 2.45 ± 0.61 to 2.80 ± 0.68, P = 0.009) when compared with a mean arterial pressure of 65 mmHg.

Conclusions

Increasing mean arterial pressure from 65 mmHg to normal levels is associated with improved microcirculation in hypertensive septic shock patients.

Trial registration

Clinicaltrials.gov: NCT01443494; registered 28 September 2011.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0866-0) contains supplementary material, which is available to authorized users.

[Catecholamines: pro and contra]

BACKGROUND

Catecholamines with vasopressor and inotropic effects are commonly used in intensive care medicine. The aim of this review is to explain some of the physiologic actions on which a catecholamine therapy is based, but also to elucidate the risks which are associated with an uncritical and excessive use of these drugs.

SIDE EFFECTS

Emphasis is placed on the myocardial damage triggered by adrenergic overstimulation. There is considerable evidence that in conditions of severe heart failure, myocardial ischemia as well as cardiogenic and septic shock especially the use of catecholamines with predominant β-adrenergic effects (epinephrine, dobutamine, dopamine) can have a negative clinical impact. A simple cardiac risk marker might be a tachycardia.

ADMINISTRATION

Vasopressor therapy with norepinephrine, based on individually applied perfusion parameters (e.g., urine output, lactate), however, seems justified in many conditions of shock and hemodynamic instability during deep analgosedation. In terms of a cardioprotective therapy, the administration of catecholamines, however, should always be reevaluated and titrated to the minimum deemed necessary.

Optimizing mean arterial pressure in septic shock: a critical reappraisal of the literature

Guidelines recommend that a mean arterial pressure (MAP) value greater than 65 mm Hg should be the initial blood pressure target in septic shock, but what evidence is there to support this statement? We searched Pubmed and Google Scholar by using the key words 'arterial pressure', 'septic shock', and 'norepinephrine' and retrieved human studies published between 1 January 2000 and 31 July 2014. We identified seven comparative studies: two randomized clinical trials and five observational studies. The results of the literature review suggest that a MAP target of 65 mm Hg is usually sufficient in patients with septic shock. However, a MAP of around 75 to 85 mm Hg may reduce the development of acute kidney injury in patients with chronic arterial hypertension. Because of the high prevalence of chronic arterial hypertension in patients who develop septic shock, this finding is of considerable importance. Future studies should assess interactions between time, fluid volumes administered, and doses of vasopressors.

Individualized early goal-directed therapy in systemic inflammation: is full utilization of preload reserve the optimal strategy?

OBJECTIVES

In severe acute pancreatitis, the administration of fluids in the presence of positive fluid responsiveness is associated with better outcome when compared to guiding therapy on central venous pressure. We compared the effects of such consequent maximization of stroke volume index with a regime using individual values of stroke volume index assessed prior to severe acute pancreatitis induction as therapeutic hemodynamic goals.

DESIGN

Prospective, randomized animal study.

SETTING

University animal research laboratory.

SUBJECTS

Thirty domestic pigs.

INTERVENTIONS

After randomization, fluid resuscitation was started 2 hours after severe acute pancreatitis induction and continued for 6 hours according to the respective treatment algorithms. In the control group, fluid therapy was directed by maximizing stroke volume index, and in the study group, stroke volume index assessed prior to severe acute pancreatitis served as primary hemodynamic goal.

MEASUREMENTS AND MAIN RESULTS

Within the first 6 hours of severe acute pancreatitis, the study group received a total of 1,935.8 ± 540.7 mL of fluids compared with 3,462.8 ± 828.2 mL in the control group (p < 0.001). Pancreatic tissue oxygenation did not differ significantly between both groups. Vascular endothelial function, measured by flow-mediated vasodilation before and 6 hours after severe acute pancreatitis induction, revealed less impairment in the study group after treatment interval (-90.76% [study group] vs -130.89% [control group]; p = 0.046). Further, lower levels of heparan sulfate (3.41 ± 5.6 pg/mL [study group] vs 43.67 ± 46.61 pg/mL [control group]; p = 0.032) and interleukin 6 (32.18 ± 8.81 pg/mL [study group] vs 77.76 ± 56.86 pg/mL [control group]; p = 0.021) were found in the study group compared with control group. Histopathological examination of the pancreatic head and corpus at day 7 revealed less edema for the study group compared with the control group (1.82 ± 0.87 [study group] vs 2.89 ± 0.33 [control group, pancreatic head]; p = 0.03; 2.2 ± 0.92 [study group] vs 2.91 ± 0.3 [control group, pancreatic corpus]; p = 0.025).

CONCLUSIONS

Individualized optimization of intravascular fluid status during the early course of severe acute pancreatitis, compared with a treatment strategy of maximizing stroke volume by fluid loading, leads to less vascular endothelial damage, pancreatic edema, and inflammatory response.

New directions for sepsis and septic shock research

BACKGROUND

Septic shock is a frequent complication in intensive care unit that can result in multiple organ failure and death. In addition, recent data suggested that severe sepsis and septic shock represent an economic burden. Therefore, septic shock is an important public health problem.

METHOD

In this review, we will focus on the recent evidences concerning the stages of septic shock, the complex macrocirculation and microcirculation relationship, and the importance of those evidences for future resuscitation goals and therapeutic strategies during late septic shock.

RESULT

Recently, two stages of septic shock are suggested. In early stage, hypovolemia is the main contributing factor. During this stage, macrocirculatory and microcirculatory changes run parallel, and fluid resuscitation seems to be effective in restoring the hemodynamic parameters. Late stage of septic shock is characterized by complex microcirculation and macrocirculation relationship.

CONCLUSIONS

Although early goal-directed therapy is a stepwise approach in the treatment of septic shock, tissue perfusion remains an important factor that contributes to septic shock outcome. Because appropriate monitoring of tissue perfusion is a matter of debt, the ideal therapeutic strategy remains a controversial issue that needs further investigations.