Peripheral and Organ Perfusion's Role in Prognosis of Disease Severity and Mortality in Severe COVID-19 Patients: Prospective Cohort Study

Severe COVID-19 is associated with a generalized inflammatory response leading to peripheral and organ perfusion disorders. Objectives: This study aimed to evaluate the usefulness of peripheral and organ perfusion assessments in the prediction of prognosis and mortality in patients with severe COVID-19. Patients and Methods: In the first 48 h of hospitalization, peripheral perfusion (saturation, Finger Infrared Thermography-FIT; Capillary Refill Time-CRT), and the color Doppler renal cortex perfusion (RCP) were estimated in a group of 102 severe COVID-19 patients. Results: In total, 40 patients experienced deterioration and required intensification of oxygen treatment, and 24 finally died. In comparison with a stable course of the disease, patients with deterioration had initially higher WBC, CRP, AST, LDH, and CRT, but a lower oxygenation ratio and RCP. Deceased patients were older, had higher CRP, LDH, and CRT, but lower hemoglobin, oxygenation ratio, and RCP compared to survivors. In the multivariable regression analysis from perfusion parameters, only RCP and CRT were independently linked with deterioration (OR 0.002, p < 0.001; OR 1.825, p = 0.003, respectively) and death (OR 0.001, p = 0.004; OR 1.910, p = 0.003, respectively). Conclusions: Initial assessment of peripheral and organ perfusion can be helpful in identifying hospitalized severe COVID-19 patients with a higher risk of deterioration and death. Capillary Refill Time and Renal Cortical Perfusion were prognostic markers of deterioration or death. On the other hand, Finger Infrared Thermography and saturation were not statistically significant in predicting patient outcome. An RCP cut-off value below 0.127 and 0.112 [cm/s] and a Capillary Refill Time longer than 3.25 and 4.25 [s] indicate the risk of deterioration or death, respectively.

[Relationship between cardiac output, heart rate and microcirculation in patients with multiorgan dysfunction syndrome]

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is one of the main causes of death in intensive care units. There is evidence that microcirculation in sepsis and coronary shock is regulated separately from hemodynamics. This study investigates the relationship between heart rate (HR), cardiac output (CO) and microcirculation in patients with MODS.

METHODS

This is a partial analysis of the "MODIFY study" (Reducing Elevated Heart Rate in Patients With Multiple Organ Dysfunction Syndrome [MODS] by Ivabradine). During the period 05/2010-09/2011, the microcirculation of 46 patients with septic and coronary MODS was measured using the sidestream dark field technique on the day of inclusion and 96 h later. Patients were randomized into a control and ivabradine treatment group.

RESULTS

Overall, there is a relevant improvement in microcirculation over time small perfused vessels, SPV [%] on day 0, d0:56.5 ± 34.2/d4:73.2 ± 22.1 (p = 0.03); perfused vessel density, PVDsmall [1/mm2] d0:7.5 ± 5.0/d4:9.8 ± 3.4 (p = 0.04); proportion of perfused vessels, PPVsmall [%] d0:51.6 ± 31.6/d4:66.7 ± 21.8 (p = 0.04); microcirculatory flow index, MFI d0:1.7 ± 1.0/d4:2.2 ± 0.7 (p = 0.05). Administration of ivabradine shows no effect. In patients with coronary MODS, there is a relevant correlation between microcirculatory parameters and cardiac output (SPV [%]: r = 0.98, p = 0.004). Patients with coronary MODS show better microcirculation values at high heart rates (> 100 bpm), while patients with septic MODS show an opposite relationship.

CONCLUSION

The results indicate that in critically ill patients, depending on the genesis of the MODS, there are different relationships between HF or CO values, on the one hand, and the parameters of the microcirculation, on the other.

Unmasking the Impact of Oxygenator-Induced Hypocapnia on Blood Lactate in Veno-Arterial Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is often associated with disturbances in acid/base status that can be triggered by the underlying pathology or the ECMO circuit itself. Extracorporeal membrane oxygenation is known to cause hypocapnia, but the impact of reduced partial pressure of carbon dioxide (pCO 2 ) on biomarkers of tissue perfusion during veno-arterial (VA)-ECMO has not been evaluated. To study the impact of low pCO 2 on perfusion indices in VA-ECMO, we placed Sprague-Dawley rats on an established VA-ECMO circuit using either an oxygen/carbon dioxide mixture (O 2 95%, CO 2 5%) or 100% O 2 delivered through the oxygenator (n = 5 per cohort). Animals receiving 100% O 2 developed a significant VA CO 2 difference (pCO 2 gap) and rising blood lactate levels that were inversely proportional to the decrease in pCO 2 values. In contrast, pCO 2 gap and lactate levels remained similar to pre-ECMO baseline levels in animals receiving the O 2 /CO 2 mixture. More importantly, there was no significant difference in venous oxygen saturation (SvO 2 ) between the two groups, suggesting that elevated blood lactate levels observed in the rats receiving 100% O 2 were a response to oxygenator induced hypocapnia and alkaline pH rather than reduced perfusion or underlying tissue hypoxia. These findings have implications in clinical and experimental extracorporeal support contexts.

Microcirculation-driven mitochondrion dysfunction during the progression of experimental sepsis

Sepsis is accompanied by a less-known mismatch between hemodynamics and mitochondrial respiration. We aimed to characterize the relationship and time dependency of microcirculatory and mitochondrial functions in a rodent model of intraabdominal sepsis. Fecal peritonitis was induced in rats, and multi-organ failure (MOF) was evaluated 12, 16, 20, 24 or 28 h later (n = 8/group, each) using rat-specific organ failure assessment (ROFA) scores. Ileal microcirculation (proportion of perfused microvessels (PPV), microvascular flow index (MFI) and heterogeneity index (HI)) was monitored by intravital video microscopy, and mitochondrial respiration (OxPhos) and outer membrane (mtOM) damage were measured with high-resolution respirometry. MOF progression was evidenced by increased ROFA scores; microcirculatory parameters followed a parallel time course from the 16th to 28th h. Mitochondrial dysfunction commenced with a 4-h time lag with signs of mtOM damage, which correlated significantly with PPV, while no correlation was found between HI and OxPhos. High diagnostic value was demonstrated for PPV, mtOM damage and lactate levels for predicting MOF. Our findings indicate insufficient splanchnic microcirculation to be a possible predictor for MOF that develops before the start of mitochondrial dysfunction. The adequate subcellular compensatory capacity suggests the presence of mitochondrial subpopulations with differing sensitivity to septic insults.

Effects of tirofiban on large vessel occlusion stroke are modified by etiology and renal function

OBJECTIVE

Renal function can modify the outcomes of large vessel occlusion (LVO) stroke across stroke etiologies in disparate degrees. The presence of renal function deficit can also impair the pharmacokinetics of tirofiban. Hence, this study aimed to investigate the roles of renal function in determining efficacy and safety of intravenous tirofiban before endovascular treatment (EVT) for acute ischemic stroke patients with large vessel occlusion (LVO).

METHODS

This study was a post hoc exploratory analysis of the RESCUE-BT trial. The primary outcome was the proportion of patients achieving functional independence (modified Rankin scale 0-2) at 90 days, and the primary safety outcome was the rate of symptomatic intracranial hemorrhage (sICH).

RESULTS

Among 908 individuals with available serum creatinine, decreased estimated glomerular filtration rate (eGFR) status was noted more commonly in patients with cardioembolic stroke (CE), while large artery atherosclerosis (LAA) was predominant in patients with normal renal function. In LAA with normal renal function, tirofiban was associated with higher rates of functional independence at 90 days (41.67% vs 59.80%, p = 0.003). However, for LVO patients with renal dysfunction, tirofiban did not improve functional outcomes for any of the etiologies (LAA, p = 0.876; CE, p = 0.662; others, p = 0.894) and significantly increased the risk of sICH among non-LAA patients (p = 0.020). Mediation analysis showed tirofiban reduced thrombectomy passes (12.27%) and drug/placebo to recanalization time (14.25%) mediated its effects on functional independence.

CONCLUSION

This present study demonstrated the importance of evaluating renal function before administering intravenous tirofiban among patients with LVO who are planned to undergo EVT.

Research progress on microcirculatory disorders in septic shock: A narrative review

Hemodynamic coherence plays a critical role in the outcomes of septic shock. Due to the potential negative consequences of microcirculatory disorders on organ failure and clinical outcomes, the maintenance of a balance between the macrocirculation and microcirculation is a topic of significant research focus. Although physical methods and specialized imaging techniques are used in clinical practice to assess microcirculation, the use of monitoring devices is not widespread. The integration of microcirculation research tools into clinical practice poses a significant challenge for the future. Consequently, this review aims to evaluate the impact of septic shock on the microcirculation, the methods used to monitor the microcirculation and highlight the importance of microcirculation in the treatment of critically ill patients. In addition, it proposes an evaluation framework that integrates microcirculation monitoring with macrocirculatory parameters. The optimal approach should encompass dynamic, multiparametric, individualized, and continuous monitoring of both the macrocirculation and microcirculation, particularly in cases of hemodynamic separation.

Resuscitation-associated endotheliopathy (RAsE): a conceptual framework based on a systematic review and meta-analysis

INTRODUCTION

Shock-induced endotheliopathy (SHINE), defined as a profound sympathoadrenal hyperactivation in shock states leading to endothelial activation, glycocalyx damage, and eventual compromise of end-organ perfusion, was first described in 2017. The aggressive resuscitation therapies utilised in treating shock states could potentially lead to further worsening endothelial activation and end-organ dysfunction.

OBJECTIVE

This study aimed to systematically review the literature on resuscitation-associated and resuscitation-induced endotheliopathy.

METHODS

A predetermined structured search of literature published over an 11-year and 6-month period (1 January 2011 to 31 July 2023) was performed in two indexed databases (PubMed/MEDLINE and Embase) per PRISMA guidelines. Inclusion was restricted to original studies published in English (or with English translation) reporting on endothelial dysfunction in critically ill human subjects undergoing resuscitation interventions. Reviews or studies conducted in animals were excluded. Qualitative synthesis of studies meeting the inclusion criteria was performed. Studies reporting comparable biomarkers of endothelial dysfunction post-resuscitation were included in the quantitative meta-analysis.

RESULTS

Thirty-two studies met the inclusion criteria and were included in the final qualitative synthesis. Most of these studies (47%) reported on a combination of mediators released from endothelial cells and biomarkers of glycocalyx breakdown, while only 22% reported on microvascular flow changes. Only ten individual studies were included in the quantitative meta-analysis based on the comparability of the parameters assessed. Eight studies measured syndecan-1, with a heterogeneity index, I2 = 75.85% (pooled effect size, mean = 0.27; 95% CI - 0.07 to 0.60; p = 0.12). Thrombomodulin was measured in four comparable studies (I2 = 78.93%; mean = 0.41; 95% CI - 0.10 to 0.92; p = 0.12). Three studies measured E-selectin (I2 = 50.29%; mean =  - 0.15; 95% CI - 0.64 to 0.33; p = 0.53), and only two were comparable for the microvascular flow index, MFI (I2 = 0%; mean =  - 0.80; 95% CI - 1.35 to - 0.26; p < 0.01).

CONCLUSION

Resuscitation-associated endotheliopathy (RAsE) refers to worsening endothelial dysfunction resulting from acute resuscitative therapies administered in shock states. In the included studies, syndecan-1 had the highest frequency of assessment in the post-resuscitation period, and changes in concentrations showed a statistically significant effect of the resuscitation. There are inadequate data available in this area, and further research and standardisation of the ideal assessment and panel of biomarkers are urgently needed.

Intracoronary imaging guided percutaneous coronary intervention outcomes among individuals with cardiogenic shock

BACKGROUND

Limited data exist around the utility of intracoronary imaging (ICI) during percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS) and cardiogenic shock (CS), who are inherently at a high risk of stent thrombosis (ST).

METHODS

All PCI procedures for ACS patients with CS in England and Wales between 2014 and 2020 were retrospectively analysed, stratified into two groups: ICI and angiography-guided groups. Multivariable logistic regression analyses were performed to examine odds ratios (OR) of in-hospital outcomes, including major adverse cardiovascular and cerebrovascular events (MACCE; composite of all-cause mortality, acute stroke/transient ischaemic attack (TIA), and reinfarction) and major bleeding, in the ICI-guided group compared with angiography-guided PCI.

RESULTS

Of 15,738 PCI procedures, 1240(7.9%) were ICI-guided. The rate of ICI use amongst those with CS more than doubled from 2014 (5.7%) to 2020 (13.3%). The ICI-guided group were predominantly younger, males, with a higher proportion of non-ST-elevation ACS and ST. MACCE was significantly lower in the ICI-guided group compared with the angiography-guided group (crude: 29.8% vs. 38.2%, adjusted odds ratio (OR) 0.65 95% confidence interval [CI] 0.56-0.76), driven by lower all-cause mortality (28.6% vs. 37.0%, OR 0.65 95% CI 0.55-0.75). There were no differences in other secondary outcomes between groups.

CONCLUSION

ICI use among CS patients has more than doubled over 6 years but remains significantly under-utilized, with less than 1-in-6 patients in receipt of ICI-guided PCI by 2020. ICI-guided PCI is associated with prognostic benefits in CS patients and should be more frequently utilized to increase their long-term survival.

The role of the microcirculation and integrative cardiovascular physiology in the pathogenesis of ICU-acquired weakness

Skeletal muscle dysfunction after critical illness, defined as ICU-acquired weakness (ICU-AW), is a complex and multifactorial syndrome that contributes significantly to long-term morbidity and reduced quality of life for ICU survivors and caregivers. Historically, research in this field has focused on pathological changes within the muscle itself, without much consideration for their in vivo physiological environment. Skeletal muscle has the widest range of oxygen metabolism of any organ, and regulation of oxygen supply with tissue demand is a fundamental requirement for locomotion and muscle function. During exercise, this process is exquisitely controlled and coordinated by the cardiovascular, respiratory, and autonomic systems, and also within the skeletal muscle microcirculation and mitochondria as the terminal site of oxygen exchange and utilization. This review highlights the potential contribution of the microcirculation and integrative cardiovascular physiology to the pathogenesis of ICU-AW. An overview of skeletal muscle microvascular structure and function is provided, as well as our understanding of microvascular dysfunction during the acute phase of critical illness; whether microvascular dysfunction persists after ICU discharge is currently not known. Molecular mechanisms that regulate crosstalk between endothelial cells and myocytes are discussed, including the role of the microcirculation in skeletal muscle atrophy, oxidative stress, and satellite cell biology. The concept of integrated control of oxygen delivery and utilization during exercise is introduced, with evidence of physiological dysfunction throughout the oxygen delivery pathway - from mouth to mitochondria - causing reduced exercise capacity in patients with chronic disease (e.g., heart failure, COPD). We suggest that objective and perceived weakness after critical illness represents a physiological failure of oxygen supply-demand matching - both globally throughout the body and locally within skeletal muscle. Lastly, we highlight the value of standardized cardiopulmonary exercise testing protocols for evaluating fitness in ICU survivors, and the application of near-infrared spectroscopy for directly measuring skeletal muscle oxygenation, representing potential advancements in ICU-AW research and rehabilitation.

Effects of Fluids on the Sublingual Microcirculation in Sepsis

Sepsis is one of the most common and deadly syndromes faced in Intensive Care settings globally. Recent advances in bedside imaging have defined the changes in the microcirculation in sepsis. One of the most advocated interventions for sepsis is fluid therapy. Whether or not fluid bolus affects the microcirculation in sepsis has not been fully addressed in the literature. This systematic review of the evidence aims to collate studies examining the microcirculatory outcomes after a fluid bolus in patients with sepsis. We will assimilate the evidence for using handheld intra vital microscopes to guide fluid resuscitation and the effect of fluid bolus on the sublingual microcirculation in patients with sepsis and septic shock. We conducted a systematic search of Embase, CENTRAL and Medline (PubMed) using combinations of the terms "microcirculation" AND "fluid" OR "fluid resuscitation" OR "fluid bolus" AND "sepsis" OR "septic shock". We found 3376 potentially relevant studies. Fifteen studies published between 2007 and 2021 fulfilled eligibility criteria to be included in analysis. The total number of participants was 813; we included six randomized controlled trials and nine non-randomized, prospective observational studies. Ninety percent used Sidestream Dark Field microscopy to examine the microcirculation and 50% used Hydroxyethyl Starch as their resuscitation fluid. There were no clear effects of fluid on the microcirculation parameters. There was too much heterogeneity between studies and methodology to perform meta-analysis. Studies identified heterogeneity of affect in the sepsis population, which could mean that current clinical classifications were not able to identify different microcirculation characteristics. Use of microcirculation as a clinical endpoint in sepsis could help to define sepsis phenotypes. More research into the effects of different resuscitation fluids on the microcirculation is needed.

Venoarterial extracorporeal membrane oxygenation flow or dobutamine to improve microcirculation during ECMO for refractory cardiogenic shock

PURPOSE

Venoarterial extracorporeal membrane oxygenation (VA ECMO) effectively supports refractory cardiogenic shock (rCS), and sustains macro- and microcirculations. We investigated the respective impact of increasing VA ECMO flow or dobutamine dose on microcirculation in stabilized VA ECMO-treated patients with rCS.

METHODS

In this prospective interventional study, we included consecutive intubated patients, with ECMO-supported rCS and hemodynamic stability, able to tolerate stepwise incremental dobutamine doses (from 5 to 20 gamma/kg/min) or ECMO flows (progressive increase by 25% above baseline ECMO flow. Baseline was defined as the lowest VA ECMO flow and dobutamine 5 μg/kg/min (DOBU₅) to maintain mean arterial pressure (MAP) ≥ 65 mmHg. Macro- and microcirculations were evaluated after 30 min at each level.

RESULTS

Fourteen patients were included. Macro- and microcirculations were assessed 2 [2-5] days post-ECMO onset. Dobutamine-dose increments did not modify any microcirculation parameters. Only the De Backer score tended to be reduced (p = 0.08) by ECMO-flow increments whereas other microcirculation parameters were not affected. These findings did not differ between patients successfully weaned-off ECMO (n = 6) or not.

CONCLUSIONS

When macrocirculation has already been restored in patients with ECMO-supported rCS, increasing dobutamine (above 5 μg/kg/min) or ECMO flow did not further improve microcirculation.

Basic mechanisms in cardiogenic shock: part 1-definition and pathophysiology

Cardiogenic shock mortality rates remain high despite significant advances in cardiovascular medicine and the widespread uptake of mechanical circulatory support systems. Except for early invasive angiography and percutaneous coronary intervention of the infarct-related artery, the most widely used therapeutic measures are based on low-quality evidence. The grim prognosis and lack of high-quality data warrant further action. Part 1 of this two-part educational review defines cardiogenic shock and discusses current treatment strategies. In addition, we summarize current knowledge on basic mechanisms in the pathophysiology of cardiogenic shock, focusing on inflammation and microvascular disturbances, which may ultimately be translated into diagnostic or therapeutic approaches to improve the outcome of our patients.

Circular RNA UBAP2 (hsa_circ_0007367) Correlates with Microcirculatory Perfusion and Predicts Outcomes of Cardiogenic Shock Patients Undergoing Extracorporeal Membrane Oxygenation Support

BACKGROUND

Severe microcirculatory disturbance is common in patients with cardiogenic shock necessitating extracorporeal membrane oxygenation (ECMO), however, biomarkers linked to microcirculation and clinical outcome are scarce. Herein we identified a circular RNA, hsa_circ_0007367, rooted from the ubiquitin-associated protein 2 (UBAP2) gene, namely circUBAP2, and evaluated its biological function and the associations with microcirculation and the prognosis.

METHODS

Patients on ECMO with cardiogenic shock were included if qualified sublingual microcirculation parameters could be obtained and were categorized into the survivor group or non-survivor group. Macro-circulatory, microcirculatory data, cytokine levels, and relative circUBAP2 expressions were collected before, at 24 h, and at ECMO weaning off, respectively. The effects of circUBAP2 on the migration, polarization, cytokine productions, and inflammatory pathways in macrophage NR8383 cells were investigated using in vitro methods.

RESULTS

Thirty-three patients with an average age of 58.0 years were enrolled, including 19 survivors and 14 non-survivors. The survivors had higher small vessel density, perfused small vessel density (PSVD), and microvascular flow index (MFI) throughout the ECMO course than did the non-survivors. Relative expression of circUBAP2 (hsa_circ_0007367) correlated with the microcirculatory parameters and satisfactorily predicted the 30-day in-hospital mortality. A multivariable logistic model was developed, showing following four predictors: age (odds ratio [OR] 1.06, 95% confidence interval [CI] 1.00-1.12), time from shock to ECMO (OR 1.10, 95% CI 1.01-1.20), PVSD (OR 0.14, 95% CI 0.02-0.89), and the circUBAP2 expression (OR 0.25, 95% CI 0.08-0.78). In addition, circUBAP2 inhibited the migratory activity and promoted M2 polarization in macrophages, declining the productions of cytokines (tumor necrosis factor [TNF]-α, interleukin [IL]-1β, and monocyte chemotactic protein [MCP]-1) and the PI3K/Akt/mTOR pathway.

CONCLUSION

The expression of circUBAP2 correlates with microcirculatory perfusion and has the potential in predicting outcomes for on-ECMO patients with cardiogenic shock.

Microcirculation during surgery

Throughout the long history of surgery, there has been great advancement in the hemodynamic management of surgical patients. Traditionally, hemodynamic management has focused on macrocirculatory monitoring and intervention to maintain appropriate oxygen delivery. However, even after optimization of macro-hemodynamic parameters, microcirculatory dysfunction, which is related to higher postoperative complications, occurs in some patients. Although the clinical significance of microcirculatory dysfunction has been well reported, little is known about interventions to recover microcirculation and prevent microcirculatory dysfunction. This may be at least partly caused by the fact that the feasibility of monitoring tools to evaluate microcirculation is still insufficient for use in routine clinical practice. However, considering recent advancements in these research fields, with more popular use of microcirculation monitoring and more clinical trials, clinicians may better understand and manage microcirculation in surgical patients in the future. In this review, we describe currently available methods for microcirculatory evaluation. The current knowledge on the clinical relevance of microcirculatory alterations has been summarized based on previous studies in various clinical settings. In the latter part, pharmacological and clinical interventions to improve or restore microcirculation are also presented.

[The role of the microcirculation in the pathogenesis of organ dysfunction]

The microcirculation includes all blood and lymph vessels with a diameter < 100 µm. Microcirculatory dysfunction is common in critically ill patients and is closely associated with both the severity of (multi-)organ dysfunction and mortality. The nature and extent of microcirculatory dysfunction differ depending on the underlying disease and are most pronounced in patients with systemic inflammation (e. g. sepsis), specific infections (e. g. malaria, dengue) or thrombocytopenia-associated multiple organ failure. This manuscript provides an overview of the pathophysiology, monitoring and therapy of microcirculatory dysfunction in the critically ill patient.

Antithrombotic and anticoagulation therapies in cardiogenic shock: a critical review of the published literature

Cardiogenic shock (CS) is a complex multifactorial clinical syndrome, developing as a continuum, and progressing from the initial insult (underlying cause) to the subsequent occurrence of organ failure and death. There is a large phenotypic variability in CS, as a result of the diverse aetiologies, pathogenetic mechanisms, haemodynamics, and stages of severity. Although early revascularization remains the most important intervention for CS in settings of acute myocardial infarction, the administration of timely and effective antithrombotic therapy is critical to improving outcomes in these patients. In addition, other clinical settings or non-acute myocardial infarction aetiologies, associated with high thrombotic risk, may require specific regimens of short-term or long-term antithrombotic therapy. In CS, altered tissue perfusion, inflammation, and multi-organ dysfunction induce unpredictable alterations to antithrombotic drugs' pharmacokinetics and pharmacodynamics. Other interventions used in the management of CS, such as mechanical circulatory support, renal replacement therapies, or targeted temperature management, influence both thrombotic and bleeding risks and may require specific antithrombotic strategies. In order to optimize safety and efficacy of these therapies in CS, antithrombotic management should be more adapted to CS clinical scenario or specific device, with individualized antithrombotic regimens in terms of type of treatment, dose, and duration. In addition, patients with CS require a close and appropriate monitoring of antithrombotic therapies to safely balance the increased risk of bleeding and thrombosis.

Heart, kidney and left ventricular assist device: a complex trio

BACKGROUND

Heart failure (HF) is a complex syndrome affecting the whole body, kidneys included. The left ventricular assist device (LVAD) is a valid option for patients with very severe HF. Focusing on renal function, LVAD implantation could theoretically reverse the detrimental effects of HF syndrome on kidneys. However, implanting an LVAD is a high-risk surgical procedure, and LVAD patients have higher risk of bleeding, device thrombosis, strokes, renal impairment, multi-organ failure and infections. Furthermore, an LVAD has its own particular effects on the renal system.

METHODS

In this review, we provide a comprehensive overview of the complex interaction between LVAD and the kidneys from the pathophysiological and clinical perspectives. An analysis of the different effects of pulsatile-flow and continuous-flow LVAD is provided.

RESULTS

Despite their limitations, creatinine-based estimated glomerular filtration rate (eGFR) formulas help to stratify patients by their post-LVAD placement prognosis. Poor basal renal function, the onset of acute kidney injury or the need for renal replacement therapy after LVAD implantation negatively influences a patient's prognosis. LVAD can also prompt an improvement in renal function, however, with some counterintuitive effects on a patient's prognosis.

CONCLUSION

It is still hard to say whether different trends in eGFR depend on different renal conditions before LVAD placement, on a patient's better overall status or on a particular patient management strategy before and/or after the device's implantation. Steps should be taken to solve this question because finding the best candidates for LVAD implantation is of paramount importance to ensure the best outcomes.

Bedside determination of microcirculatory oxygen delivery and uptake: a prospective observational clinical study for proof of principle

Assessment of microcirculatory functional capacity is considered to be of prime importance for therapy guidance and outcome prediction in critically ill intensive care patients. Here, we show determination of skin microcirculatory oxygen delivery and consumption rates to be a feasible approach at the patient’s bedside. Real time laser-doppler flowmetry (LDF) and white light spectrophotometry (WLS) were used for assessment of thenar skin microperfusion, regional Hb and postcapillary venous oxygen saturation before and after forearm ischemia. Adapted Fick’s principle equations allowed for calculation of microcirculatory oxygen delivery and uptake. Patient groups with expected different microcirculatory status were compared [control (n = 20), sepsis-1/2 definition criteria identified SIRS (n = 10) and septic shock patients (n = 20), and the latter group further classified according to sepsis-3 definition criteria in sepsis (n = 10) and septic shock (n = 10)], respectively. In otherwise healthy controls, microcirculatory oxygen delivery and uptake approximately doubled after ischemia with maximum values (mDO2max and mVO2max) significantly lower in SIRS or septic patient groups, respectively. Scatter plots of mVO2max and mDO2max values defined a region of unphysiological low values not observed in control but in critically ill patients with the percentage of dots within this region being highest in septic shock patients. LDF and WLS combined with vasoocclusive testing reveals significant differences in microcirculatory oxygen delivery and uptake capacity between control and critically ill patients. As a clinically feasible technique for bedside determination of microcirculatory oxygen delivery and uptake, LDF and WLS combined with vasoocclusive testing holds promise for monitoring of disease progression and/or guidance of therapy at the microcirculatory level to be tested in further clinical trials.

ClinicalTrials.gov: NCT01530932.

Pathophysiology of cardiogenic shock

PURPOSE OF REVIEW

We describe the pathophysiology of cardiogenic shock (CS), from the main pathways to the inflammatory mechanisms and the proteomic features.

RECENT FINDINGS

Although the classical pathophysiological pathways underlying CS, namely reduced organ perfusion due to inadequate cardiac output and peripheral vasoconstriction, have been well-established for a long time, the role of macro-and micro-hemodynamics in the magnitude of the disease and its prognosis has been investigated extensively only over the last few years. Moreover, to complete the complex picture of CS pathophysiology, the study of cytokine cascade, inflammation, and proteomic analysis has been addressed recently.

SUMMARY

Understanding the pathophysiology of CS is important to treat it optimally.

Feasibility study of incident dark-field video microscope for measuring microcirculatory variables in the mouse dorsal skinfold chamber model

Background

Despite the importance of microcirculation in organ function, monitoring microcirculation is not a routine practice. With developments in microscopic technology, incident dark field (IDF) microscopy (Cytocam) has allowed visualization of the microcirculation. Dorsal skinfold chamber (DSC) mouse model has been used to investigate microcirculation physiology. By employing Cytocam-IDF imaging with DSC model to assess microcirculatory alteration in lipopolysaccharide (LPS)-induced endotoxemia, we attempted to validate availability of Cytocam-IDF imaging of microcirculation.

Methods

DSC was implanted in eight BALB/c mice for each group; control and sepsis. Both groups were given 72 hours to recover from surgery. The sepsis group had an additional 24-hour period of recovery post-LPS injection (4 mg/kg). Subsequently, a video of the microcirculation was recorded using Cytocam. Data on microcirculatory variables were obtained. Electron microscopy was implemented using lanthanum fixation to detect endothelial glycocalyx degradation.

Results

The microcirculatory flow index was significantly lower (control, 2.8±0.3; sepsis, 2.1±0.8; P=0.033) and heterogeneity index was considerably higher (control, 0.10±0.15; sepsis, 0.53±0.48; P=0.044) in the sepsis group than in the control group. Electron microscopy revealed glycocalyx demolishment in the sepsis group.

Conclusions

Cytocam showed reliable ability for observing changes in the microcirculation under septic conditions in the DSC model. The convenience and good imaging quality and the automatic analysis software available for Cytocam-IDF imaging, along with the ability to perform real-time in vivo experiments in the DSC model, are expected to be helpful in future microcirculation investigations.

Microvascular Reactivity Measured by Dynamic Near-infrared Spectroscopy Following Induction of General Anesthesia in Healthy Patients: Observation of Age-related Change

Background: The purpose of this study was to investigate the effect of general anesthesia on microvascular reactivity and tissue oxygen saturation (StO₂) using near-infrared spectroscopy in conjunction with vascular occlusion tests (VOT). Age-related changes of microvascular reactivity, that is, the capacity of capillary recruitment, were examined. Methods: This prospective observational study was performed on 60 patients without comorbidities who underwent elective surgery under general anesthesia. Baseline StO₂ on thenar eminence, hemodynamics, and laboratory profile were monitored before (T0) and 30 min after general anesthesia (T1). During VOT, occlusion slope representing oxygen consumption of muscle and recovery slope representing microvascular reactivity were also collected at T0 and T1. Results: Baseline StO₂ and minimum / maximum StO₂ during VOT increased under general anesthesia. Occlusion slope decreased while the recovery slope increased under general anesthesia. To observe aging effect, Receiver operating characteristic analysis was performed and age less than 65 years old showed a fair performance in predicting the increase of microvascular reactivity after the induction of anesthesia (AUC 0.733, 95% CI 0.594-0.845, P= 0.003). For age-related analyses, 27 patients of younger group (< 65 years) and 26 patients of older group (≥ 65 years) were divided. Recovery slope significantly increased under general anesthesia in younger group (2.44 [1.91-2.81] % ∙ sec^-1 at T0 and 3.59 [2.58-3.51] % ∙ sec^-1 at T1, P <0.001), but not in older group (2.61 [2.21-3.20] % ∙ sec^-1 at T0, 2.63 [1.90-3.60] % ∙ sec^-1 at T1, P = 0.949). Conclusions: General anesthesia could improve StO₂ through increase of microvascular reactivity and decrease of tissue metabolism. However, microvascular reactivity to capillary recruitment under general anesthesia significantly improves in younger patients, not in older patients.

Veno-arterial CO2 difference and respiratory quotient after cardiac arrest: An observational cohort study

PURPOSE

To characterize venous-arterial CO₂ difference (ΔpCO₂) and the respiratory quotient (RQ) in post cardiac arrest patients and evaluate the association between these parameters and patient outcome.

MATERIALS AND METHODS

Data were obtained retrospectively from post cardiac arrest patients admitted between 2007 and 2016 to a medical intensive care unit. Comatose, adult patients in whom arterial and venous blood gas analyses were concomitantly performed in the first 24 h were included. Patients were grouped according to the time-point of sampling; 0-6, 6-12 and 12-24 h after admission.

RESULTS

308 patients were included; 174 (56%) died before ICU discharge and 212 (69%) had an unfavorable neurologic outcome. RQ was associated with ICU mortality (OR:1.09 (95%CI: 1.04-1.14; p < 0.01)), although not with neurological outcome. ΔpCO₂ was negatively associated with both ICU mortality (OR: 0.92 (95%CI: 0.86-0.99; p = 0.02)) and poor neurologic outcome (adjusted OR: 0.93 (95%CI: 0.87-0.99; p = 0.02)). ΔpCO₂ predicted an elevated RQ; a ΔpCO₂ above 8.5 mmHg identified a high RQ with reasonable sensitivity and specificity.

CONCLUSIONS

RQ was associated with ICU mortality and ΔpCO₂ identified elevated RQ in the early phase after cardiac arrest. However, ΔpCO₂ were negatively associated with both ICU mortality and neurologic outcome.

Microvascular dysfunction in septic and dengue shock: Pathophysiology and implications for clinical management

The microcirculation comprising of arterioles, capillaries and post-capillary venules is the terminal vascular network of the systemic circulation. Microvascular homeostasis, comprising of a balance between vasoconstriction, vasodilation and endothelial permeability in healthy states, regulates tissue perfusion. In severe infections, systemic inflammation occurs irrespective of the infecting microorganism(s), resulting in microcirculatory dysregulation and dysfunction, which impairs tissue perfusion and often precedes end-organ failure. The common hallmarks of microvascular dysfunction in both septic shock and dengue shock, are endothelial cell activation, glycocalyx degradation and plasma leak through a disrupted endothelial barrier. Microvascular tone is also impaired by a reduced bioavailability of nitric oxide. In vitro and in vivo studies have however demonstrated that the nature and extent of microvascular dysfunction as well as responses to volume expansion resuscitation differ in these two clinical syndromes. This review compares and contrasts the pathophysiology of microcirculatory dysfunction in septic versus dengue shock and the attendant effects of fluid administration during resuscitation.

Divergent Effects of the N-Methyl-D-Aspartate Receptor Antagonist Kynurenic Acid and the Synthetic Analog SZR-72 on Microcirculatory and Mitochondrial Dysfunction in Experimental Sepsis

Introduction: Sepsis is a dysregulated host response to infection with macro- and microhemodynamic deterioration. Kynurenic acid (KYNA) is a metabolite of the kynurenine pathway of tryptophan catabolism with pleiotropic cell-protective effects under pro-inflammatory conditions. Our aim was to investigate whether exogenously administered KYNA or the synthetic analog SZR-72 affects the microcirculation and mitochondrial function in a clinically relevant rodent model of intraabdominal sepsis.

Methods: Male Sprague–Dawley rats (n = 8/group) were subjected to fecal peritonitis (0.6 g kg⁻¹ feces ip) or a sham operation. Septic animals were treated with sterile saline or received ip KYNA or SZR-72 (160 μmol kg⁻¹ each) 16 and 22 h after induction. Invasive monitoring was performed on anesthetized animals to evaluate respiratory, cardiovascular, renal, hepatic and metabolic dysfunctions (PaO₂/FiO₂ ratio, mean arterial pressure, urea, AST/ALT ratio and lactate levels, respectively) based on the Rat Organ Failure Assessment (ROFA) score. The ratio of perfused vessels (PPV) of the ileal serosa was quantified with the intravital imaging technique. Complex I- and II-linked (CI; CII) oxidative phosphorylation capacities (OXPHOS) and mitochondrial membrane potential (ΔΨmt) were evaluated by High-Resolution FluoRespirometry (O2k, Oroboros, Austria) in liver biopsies. Plasma endothelin-1 (ET-1), IL-6, intestinal nitrotyrosine (NT) and xanthine oxidoreductase (XOR) activities were measured as inflammatory markers.

Results: Sepsis was characterized by an increased ROFA score (5.3 ± 1.3 vs. 1.3 ± 0.7), increased ET-1, IL-6, NT and XOR levels, and decreased serosal PPV (65 ± 12% vs. 87 ± 7%), ΔΨmt and CI–CII-linked OXPHOS (73 ± 16 vs. 158 ± 14, and 189 ± 67 vs. 328 ± 81, respectively) as compared to controls. Both KYNA and SZR-72 reduced systemic inflammatory activation; KYNA treatment decreased serosal perfusion heterogeneity, restored PPV (85 ± 11%) and complex II-linked OXPHOS (307 ± 38), whereas SZR-72 improved both CI- and CII-linked OXPHOS (CI: 117 ± 18; CII: 445 ± 107) without effects on PPV 24 h after sepsis induction.

Conclusion: Treatment with SZR-72 directly modulates mitochondrial respiration, leading to improved conversion of ADP to ATP, while administration of KYNA restores microcirculatory dysfunction. The results suggest that microcirculatory and mitochondrial resuscitation with KYNA or the synthetic analog SZR-72 might be an appropriate supportive tool in sepsis therapy.

Evaluation of jejunal microvasculature of healthy anesthetized dogs with sidestream dark field video microscopy

OBJECTIVE

To determine the feasibility of sidestream dark field (SDF) video microscopy for the evaluation of the jejunal microvasculature of healthy dogs.

ANIMALS

30 healthy sexually intact female shelter dogs anesthetized for ovariohysterectomy.

PROCEDURES

Preoperative physical and clinicopathologic assessments were performed to confirm health status. Then healthy dogs were anesthetized, and the abdomen was incised at the ventral midline for ovariohysterectomy and jejunal microvasculature evaluation. An SDF video microscope imaged the microvasculature of 2 sites of a portion of the jejunum, and recorded videos were analyzed with software capable of quantitating parameters of microvascular health. Macrovascular parameters (heart rate, respiratory rate, and hemoglobin oxygen saturation) were also recorded during anesthesia.

RESULTS

Quantified jejunal microvascular parameters included valid microvascular density (mean ± SD, 251.72 ± 97.10 μm/mm), RBC-filling percentage (66.96 ± 8.00%), RBC column width (7.11 ± 0.72 μm), and perfused boundary region (2.17 ± 0.42 μm). The perfused boundary region and RBC-filling percentage had a significant negative correlation. Strong to weak positive correlations were noted among the perfused boundary regions of small-, medium-, and large-sized microvessels. No significant correlations were identified between microvascular parameters and age, body weight, preoperative clinicopathologic results, or macrovascular parameters.

CONCLUSIONS AND CLINICAL RELEVANCE

Interrogation of the jejunal microvasculature of healthy dogs with SDF video microscopy was feasible. Results of this study indicated that SDF video microscopy is worth additional investigation, including interrogation of diseased small intestine in dogs.

Post-operative renal failure management in mechanical circulatory support patients

Acute kidney injury (AKI) occurs commonly in patients requiring mechanical circulatory support (MCS) after cardiothoracic surgery. The prognostic implications of AKI in this patient group relate closely to the pathophysiology and risk factors associated with the underlying disease; pre-operative, intra-operative, and post-operative variables; hemodynamic factors; and type of support device used. General approaches to AKI management, including prevention strategies, medical management, and hemodynamic support, are also applicable in patients requiring MCS. Approaches to renal replacement therapy vary depend on patient factors, device-specific factors, and local preferences and experience. In this invited narrative review, we discuss the pathophysiology, risk factors, and prognostic implications of AKI in post-operative adult patients following institution of MCS. Management strategies for AKI are presented with a focus on those supported with either extracorporeal membrane oxygenation or a ventricular assist device.

Variations of Cutaneous Capnometry and Perfusion Index During a Heating Challenge is Early Impaired in Septic Shock and Related to Prognostic in Non-Septic Shock

INTRODUCTION

In shock, the increase in cutaneous-to-arterial carbon dioxide partial pressure (Pc-aCO2) and the decrease in the perfusion index (PI) are related to macrovascular or microvascular alterations. We hypothesized that inducing cutaneous vasodilation and local perfusion with heat could provide a noninvasive tool to monitor microvascular reactivity.

OBJECTIVES

This study aimed to develop a noninvasive approach, the heating challenge (HC), to monitor the microvascular reactivity of patients with shock and to evaluate the potential relationship with outcome.

METHODS

After ethics committee agreement was obtained, 59 shock patients, including 37 septic shock, 22 non-septic shock (14 cardiogenic and eight hemorrhagic), 10 intensive care unit (ICU)-controls and 12 healthy volunteers, were included in this study. The HC consisted of heating the ear lobe PcCO2 sensor from 37° to 45° over 5 min and recording PcCO2 and PI variations (ΔPcCO2 and PImax/min). HC was performed on admission and during the first 48 h of hospitalization.

RESULTS

Pc-aCO2 was significantly higher in shock patients than ICU-controls at baseline (P < 0.05). HC led to a decrease in PcCO2 and an increase in PI in the healthy volunteers (ΔPcCO2 = -9.0 ± 4.6% and PImax/min = 5.5 ± 1.9). On admission, non-septic shock patients (cardiogenic and hemorrhagic shocks) had an HC response profile identical to that of healthy volunteers and ICU-controls. In contrast, septic shock patients had a lower ΔPcCO 2 and PImax/min compared to healthy volunteers and all other groups (P < 0.05). After the first day, the combination of a Pc-aCO2 >17 mm Hg with a positive ΔPcCO2 could predict mortality with a specificity of 82% and a sensitivity of 93%.

CONCLUSIONS

HC appears to be a dynamic test to classify vascular reactivity alterations in shock. At baseline, HC results were impaired in septic patients and conserved in non-septic patients. After the first day, the association between Pc-aCO2 and ΔPcCO2 was strongly related to prognosis in shock patients.

[Association between peripheral perfusion, microcirculation and mortality in sepsis: a systematic review]

Although increasing evidence supports the monitoring of peripheral perfusion in septic patients, no systematic review has been undertaken to explore the strength of association between poor perfusion assessed in microcirculation of peripheral tissues and mortality. A search of the most important databases was carried out to find articles published until February 2018 that met the criteria of this study using different keywords: sepsis, mortality, prognosis, microcirculation and peripheral perfusion. The inclusion criteria were studies that assessed association between peripheral perfusion/microcirculation and mortality in sepsis. The exclusion criteria adopted were: review articles, animal/pre-clinical studies, meta-analyzes, abstracts, annals of congress, editorials, letters, case-reports, duplicate and articles that did not present abstracts and/or had no text. In the 26 articles were chosen in which 2465 patients with sepsis were evaluated using at least one recognized method for monitoring peripheral perfusion. The review demonstrated a heterogeneous critically ill group with a mortality-rate between 3% and 71% (median=37% [28%-43%]). The most commonly used methods for measurement were Near-Infrared Spectroscopy (NIRS) (7 articles) and Sidestream Dark-Field (SDF) imaging (5 articles). The vascular bed most studied was the sublingual/buccal microcirculation (8 articles), followed by fingertip (4 articles). The majority of the studies (23 articles) demonstrated a clear relationship between poor peripheral perfusion and mortality. In conclusion, the diagnosis of hypoperfusion/microcirculatory abnormalities in peripheral non-vital organs was associated with increased mortality. However, additional studies must be undertaken to verify if this association can be considered a marker of the gravity or a trigger factor for organ failure in sepsis.

Clinical use of plasma lactate concentration. Part 2: Prognostic and diagnostic utility and the clinical management of hyperlactatemia

OBJECTIVE

To review the current literature pertaining to the use of lactate as a prognostic indicator and therapeutic guide, the utility of measuring lactate concentrations in body fluids other than blood or plasma, and the clinical management of hyperlactatemia in dogs, cats, and horses.

DATA SOURCES

Articles were retrieved without date restrictions primarily via PubMed, Scopus, and CAB Abstracts as well as by manual selection.

HUMAN AND VETERINARY DATA SYNTHESIS

Increased plasma lactate concentrations are associated with increased morbidity and mortality. In populations with high mortality, hyperlactatemia is moderately predictive in identifying nonsurvivors. Importantly, eulactatemia predicts survival better than hyperlactatemia predicts death. Consecutive lactate measurements and calculated relative measures appear to outperform single measurements. The use of lactate as a therapeutic guide has shown promising results in people but is relatively uninvestigated in veterinary species. Increased lactate concentrations in body fluids other than blood should raise the index of suspicion for septic or malignant processes. Management of hyperlactatemia should target the underlying cause.

CONCLUSION

Lactate is a valuable triage and risk stratification tool that can be used to separate patients into higher and lower risk categories. The utility of lactate concentration as a therapeutic target and the measurement of lactate in body fluids shows promise but requires further research.

Septic shock resuscitation in the first hour

PURPOSE OF REVIEW

We reviewed the recent advances in the initial approach to resuscitation of sepsis and septic shock patients.

RECENT FINDINGS

Sepsis and septic shock are life-threatening emergencies. Two key interventions in the first hour include timely antibiotic therapy and resuscitation. Before any laboratory results, the need for resuscitation is considered if a patient with suspected infection has low blood pressure (BP) or impaired peripheral circulation found at clinical examination. Until now, this early resuscitation in sepsis and septic shock was supported by improvements in outcome seen with goal-directed therapy. However, three recent, goal-directed therapy trials failed to replicate the originally reported mortality reductions, prompting a debate on how this early resuscitation should be performed. As resuscitation is often focussed on macrociculatory goals such as optimizing central venous pressure, the discordance between microcirculatory and macrocirculatory optimization during resuscitation is a potential argument for the lack of outcome benefit in the newer trials. Vasoactive drug dose and large volume resuscitation-associated-positive fluid balance, are independently associated with worse clinical outcomes in critically ill sepsis and septic shock patients. As lower BP targets and restricted volume resuscitation are feasible and well tolerated, should we consider a lower BP target to reduce the adverse effects of catecholamine' and excess resuscitation fluids. Evidence guiding fluids, vasopressor, and inotrope selection remains limited.

SUMMARY

Though the early resuscitation of sepsis and septic shock is key to improving outcomes, ideal resuscitation targets are elusive. Distinction should be drawn between microcirculatory and macrocirculatory changes, and corresponding targets. Common components of resuscitation bundles such as large volume resuscitation and high-dose vasopressors may not be universally beneficial. Microcirculatory targets, individualized resuscitation goals, and reassessment of completed trials using the updated septic shock criteria should be focus areas for future research.

Microcirculation-mediated preconditioning and intracellular hypothermia

Microcirculation is a network of perfused capillaries that connects macrocirculation with the cells. Although research has provided insight into microcirculatory blood flow, our knowledge remains limited. In this article, we propose a new role of microcirculation in physiological and shock states. In healthy individuals, microcirculation maintains cellular homeostasis via preconditioning. When blood volume decreases, the ensuing microcirculatory changes result in heterogeneity of perfusion and tissue oxygenation. Initially, this is partly compensated by the preserved autoregulation and the increase in the metabolism rate of cells, but at later stages, the loss of autoregulation activates the cascade of intracellular hypothermia.

Enhanced Recovery after Vascular Surgery

The beginnings of the enhanced recovery after surgery (ERAS) program were first developed for patients in colorectal surgery, and after it was established as the standard of care in this surgical field, it began to be applied in many others surgical areas. This is multimodal, evidence-based approach program and includes simultaneous optimization of preoperative status of patients, adequate selection of surgical procedure and postoperative management. The aim of this program is to reduce complications, the length of hospital stay and to improve the patients outcome. Over the past decades, special attention was directed to the postoperative management in vascular surgery, especially after major vascular surgery because of the great risk of multiorgan failure, such as: respiratory failure, myocardial infarction, hemodynamic instability, coagulopathy, renal failure, neurological disorders, and intra-abdominal complications. Although a lot of effort was put into it, there is no unique acceptable program for ERAS in this surgical field, and there is still a need to point out the factors responsible for postoperative outcomes of these patients. So far, it is known that special attention should be paid to already existing diseases, type and the duration of the surgical intervention, hemodynamic and fluid management, nutrition, pain management, and early mobilization of patients.

Hyperglycemia induced testicular damage in type 2 diabetes mellitus rats exhibiting microcirculation impairments associated with vascular endothelial growth factor decreased via PI3K/Akt pathway

As an endocrine disease, type 2 diabetes mellitus (T2DM) can cause testicular damage which induces male infertility. However, the underlying mechanism is still not clear. We prove that T2DM induced testicular microcirculation impairment involves the decrease of VEGF and these actions are regulated by PI3K/Akt pathway. In our study, rats were divided into three groups (n=8): control group, diabetes group and diabetes + VEGF group. Intraperitoneal injection of streptozotocin (STZ, 65mg/Kg, at 9^th week) and daily high-fat diet were used to establish T2DM rat model. Serum glucose in diabetes group and diabetes + VEGF group obviously exceeded 13mmol/L after STZ injection. Immunohistochemical studies indicated that VEGF level in diabetes group significantly decreased. In diabetes group, testicular blood velocity and vascular area reduced evaluated by Doppler and FITC. Furthermore, atrophic testicular morphology and increasing apoptosis cells were evaluated by haematoxylin and eosin staining and TUNEL assay. In diabetes + VEGF group, the administration of VEGF (intraperitoneally, 10mg/kg) can significantly alleviated hyperglycemia-induced impairment of testes in above aspects. Finally, we used Western blot to analyze the mechanism of hyperglycemia-induced testicular VEGF decrease. The results indicated that hyperglycemia-induced VEGF decreased is regulated by PI3K/Akt pathway in Rats testicular sertoli cells (RTSCs). Together, we demonstrate that T2DM can reduce testicular VEGF expression, which results in testicular microcirculation impairment, and then induces testicular morphological disarrangement and functional disorder. These actions are triggered by PI3K/Akt pathway. Our findings provide solid evidence for VEGF becoming a therapeutic target in T2DM related male infertility.

Septic Shock

For more than 20 years, sepsis has been defined as symptoms associated with the response to microorganism infection, which was more specifically called systemic inflammatory response syndrome (SIRS). With the evidence of organ failure, it was called severe sepsis, and this could lead to hypotension (septic shock). However, with the deep understanding of the pathophysiology of sepsis, sepsis has been known as both inflammatory and anti-inflammatory. Additionally, the classic use of SIRS could lead to overestimation of sepsis. For example, usual common cold could be identified as sepsis in classic definition. With this background, new sepsis definition, Sepsis 3, was introduced and sepsis was defined as a “life-threatening organ dysfunction caused by a dysregulated host response to infection.” The management of sepsis has been changed dramatically, with the development of Surviving Sepsis Campaign, which substantially increased the survival of sepsis. However, this is not with the help of a new drug, but the implementation of a treatment system. Unfortunately, no specific drug for sepsis has survived in clinical use even though many candidate drugs have been successfully investigated in preclinical setting, and this leads to the new approach to the sepsis.

Intestinal microcirculation and mucosal oxygenation during hemorrhagic shock and resuscitation at different inspired oxygen concentrations

BACKGROUND

Hypotensive resuscitation is the standard of care of hemorrhagic shock resuscitation. The optimal level of arterial pressure is debated and there is a lack of data on relationships between arterial pressure, microcirculation and tissue oxygenation. We investigated the relationship between mean arterial pressure, intestinal microcirculation and mucosal oxygen tension during hemorrhagic shock and resuscitation at different inspired oxygen fraction concentration.

METHODS

The study was divided into two phases: 32 mice were progressively exsanguinated and then transfused in mean arterial pressure (MAP)-titrated steps of 10 mm Hg. Mice were randomized to four experimental groups: a control group in which sham mice underwent a laparotomy and three interventional groups with a common phase of exsanguination followed by progressive resuscitation at three different inspired oxygen concentrations (FIO2) (15%, 30%, and 100%). Intestinal mucosal oxygenation (intestinal PO2) and microcirculatory parameters were recorded at each 10 mm Hg MAP step.

RESULTS

During exsanguination, intestinal PO2 decreased linearly with MAP levels. Microcirculatory parameters decreased nonlinearly with MAP levels while they had a linear relationship with intestinal PO2. Intestinal mucosal hypoxia (PO2 ≤ 20 mm Hg) began at a MAP of 60 mm Hg and MAP < 60 mm Hg was associated with a high percentage of animal with intestinal hypoxia (≥32%). Combination of MAP and microcirculatory parameters was superior to MAP alone at predicting mucosal oxygenation. Inversely, during resuscitation with FIO2 = 30%, the microcirculatory parameters increased linearly with MAP levels while they had a nonlinear relationship with intestinal PO2. Hypoxia (FIO2 = 15%) was poorly tolerated. In hyperoxic group (FIO2 = 100%) intestinal PO2 became significantly higher than baseline values as soon as 50 mm Hg MAP.

CONCLUSION

During hemorrhagic shock, intestinal PO2 decreased linearly with MAP levels and microcirculatory parameters. Associating MAP and microcirculatory parameters allowed a better prediction of intestinal PO2 than MAP alone. A MAP < 60 mm Hg was associated with a high percentage of animal with intestinal hypoxia. Normoxic resuscitation (FIO2 = 30%) was sufficient to restore intestinal PO2.

Effects of volume resuscitation on the microcirculation in animal models of lipopolysaccharide sepsis: a systematic review

Background

Recent research has identified an increased rate of mortality associated with fluid bolus therapy for severe sepsis and septic shock, but the mechanisms are still not well understood. Fluid resuscitation therapy administered for sepsis and septic shock targets restoration of the macro-circulation, but the pathogenesis of sepsis is complex and includes microcirculatory dysfunction.

Objective

The objective of the study is to systematically review data comparing the effects of different types of fluid resuscitation on the microcirculation in clinically relevant animal models of lipopolysaccharide-induced sepsis.

Methods

A structured search of PubMed/MEDLINE and EMBASE for relevant publications from 1 January 1990 to 31 December 2015 was performed, in accordance with PRISMA guidelines.

Results

The number of published papers on sepsis and the microcirculation has increased steadily over the last 25 years. We identified 11 experimental animal studies comparing the effects of different fluid resuscitation regimens on the microcirculation. Heterogeneity precluded any meta-analysis.

Conclusions

Few animal model studies have been published comparing the microcirculatory effects of different types of fluid resuscitation for sepsis and septic shock. Biologically relevant animal model studies remain necessary to enhance understanding regarding the mechanisms by which fluid resuscitation affects the microcirculation and to facilitate the transfer of basic science discoveries to clinical applications.

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.

Impact of microcirculatory video quality on the evaluation of sublingual microcirculation in critically ill patients

We aimed to assess the impact of image quality on microcirculatory evaluation with sidestream dark-field (SDF) videomicroscopy in critically ill patients and explore factors associated with low video quality. This was a retrospective analysis of a single-centre prospective observational study. Videos of the sublingual microcirculation were recorded using SDF videomicroscopy in 100 adult patients within 12 h from admittance to the intensive care unit and every 24 h until discharge/death. Parameters of vessel density and perfusion were calculated offline for small vessels. For all videos, a quality score (-12 = unacceptable, 1 = suboptimal, 2 = optimal) was assigned for brightness, focus, content, stability, pressure and duration. Videos with a total score ≤8 were deemed as unacceptable. A total of 2455 videos (853 triplets) was analysed. Quality was acceptable in 56 % of videos. Lower quality was associated with worse microvascular density and perfusion. Unreliable triplets (≥1 unacceptable or missing video, 65 % of total) showed lower vessel density, worse perfusion and higher flow heterogeneity as compared to reliable triplets (p < 0.001). Quality was higher among triplets collected by an extensively-experienced investigator or in patients receiving sedation or mechanical ventilation. Perfused vessel density was higher in patients with Glasgow Coma Scale (GCS) ≤8 (18.9 ± 4.5 vs. 17.0 ± 3.9 mm/mm² in those with GCS >8, p < 0.001) or requiring mechanical ventilation (18.0 ± 4.5 vs. 17.2 ± 3.8 mm/mm² in not mechanically ventilated patients, p = 0.059). We concluded that SDF video quality depends on both the operator's experience and patient's cooperation. Low-quality videos may produce spurious data, leading to an overestimation of microvascular alterations.

Postoperative management

Most patients undergoing major aortic surgery have multiple comorbidities and are at high risk of postoperative complications that affect multiple organ systems. Different aortic pathologies and surgical repair techniques have specific impact on the postoperative course. Ischemia-reperfusion injury is the common denominator in aortic surgery and influences the integrity of end-organ function. Common postoperative problems include hemodynamic instability due to the immediate inflammatory response, renal impairment, spinal cord ischemia, respiratory failure with prolonged mechanical ventilation, and gastrointestinal symptoms such as ileus or mesenteric ischemia. Focused care bundles to establish homeostasis and a team working toward an early functional recovery determine the success of effective rehabilitation and outcomes after aortic surgery.

Context-sensitive fluid therapy in critical illness

Microcirculatory alterations are frequently observed in critically ill patients undergoing major surgery and those who suffer from trauma or sepsis. Despite the need for adequate fluid administration to restore microcirculation, there is no consensus regarding optimal fluid therapy for these patients. The recent recognition of the importance of the endothelial glycocalyx layer in capillary fluid and solute exchange has largely changed our views on fluid therapy in critical illness. Given that disease status largely differs among critically ill patients, fluid therapy must not be considered generally, but rather tailored to the clinical condition of each patient. This review outlines the current understanding of context-sensitive volume expansion by fluid solutions and considers its clinical implications for critically ill patients. The modulation of capillary hydrostatic pressure through the appropriate use of vasopressors may increase the effectiveness of fluid infusion and thereby reduce detrimental effects resulting from excessive fluid administration.