Assessment of microcirculation in cardiogenic shock

Resuscitating the macro- vs. microcirculation in septic shock

PURPOSE OF REVIEW

This review summarizes current literature about the relationships between macro and microcirculation and their practical clinical implications in children with septic shock.

RECENT FINDINGS

Current evidence from experimental and clinical observational studies in children and adults with septic shock reveals that the response to treatment and resuscitation is widely variable. Furthermore, there is a loss of hemodynamic coherence, as resuscitation-induced improvement in macrocirculation (systemic hemodynamic parameters) does not necessarily result in a parallel improvement in the microcirculation. Therefore, patient-tailored monitoring is essential in order to adjust treatment requirements during resuscitation in septic shock. Optimal monitoring must integrate macrocirculation (heart rate, blood pressure, cardiac output, and ultrasound images), microcirculation (videomicroscopy parameters and capillary refill time) and cellular metabolism (lactic acid, central venous blood oxygen saturation, and difference of central venous to arterial carbon dioxide partial pressure).

SUMMARY

There is a dire need for high-quality studies to assess the relationships between macrocirculation, microcirculation and tissue metabolism in children with septic shock. The development of reliable and readily available microcirculation and tissue perfusion biomarkers (other than lactic acid) is also necessary to improve monitoring and treatment adjustment in such patients.

Cardiogenic shock as a health issue. Physiology, classification, and detection

Cardiogenic shock (CS) is a heterogeneous syndrome with high mortality and a growing incidence. It is characterized by an imbalance between the tissue oxygen demands and the capacity of the cardiovascular system to meet these demands, due to acute cardiac dysfunction. Historically, acute coronary syndromes have been the primary cause of CS. However, non-ischemic cases have seen a rise in incidence. The pathophysiology involves ischemic damage of the myocardium and a sympathetic, renin-angiotensin-aldosterone system and inflammatory response, perpetuating the situation of tissue hypoperfusion and ultimately leading to multiorgan dysfunction. The characterization of CS patients through a triaxial assessment and the widespread use of the Society for Cardiovascular Angiography and Interventions (SCAI) scale has allowed standardization of the severity stratification of CS; this, coupled with early detection and the "hub and spoke" approach, could contribute to improving the prognosis of these patients.

Sublingual Microcirculation in Temporary Mechanical Circulatory Support: A Current State of Knowledge

Cardiogenic shock causes hypoperfusion within the microcirculation, leading to impaired oxygen delivery, cell death, and progression of multiple organ failure. Mechanical circulatory support (MCS) is the last line of treatment for cardiac failure. The goal of MCS is to ensure end-organ perfusion by maintaining perfusion pressure and total blood flow. However, machine-blood interactions and the nonobvious translation of global macrohemodynamics into the microcirculation suggest that the use of MCS may not necessarily be associated with improved capillary flow. With the use of hand-held vital microscopes, it is possible to assess the microcirculation at the bedside. The paucity of literature on the use of microcirculatory assessment suggests the need for an in-depth look into microcirculatory assessment within the context of MCS. The purpose of this review is to discuss the possible interactions between MCS and microcirculation, as well as to describe the research conducted in this area. Regarding sublingual microcirculation, 3 types of MCS will be discussed: venoarterial extracorporeal membrane oxygenation, intra-aortic balloon counterpulsation, and microaxial flow pumps (Impella).

Mottling as a prognosis marker in cardiogenic shock

AIMS

Impact of skin mottling has been poorly studied in patients admitted for cardiogenic shock. This study aimed to address this issue and identify determinants of 30-day and 1-year mortality in a large cardiogenic shock cohort of all etiologies.

METHODS AND RESULTS

FRENSHOCK is a prospective multicenter observational registry conducted in French critical care units between April and October, 2016. Among the 772 enrolled patients (mean age 65.7 ± 14.9 years; 71.5% male), 660 had skin mottling assessed at admission (85.5%) with almost 39% of patients in cardiogenic shock presenting mottling. The need for invasive respiratory support was significantly higher in patients with mottling (50.2% vs. 30.1%, p < 0.001) and likewise for the need for renal replacement therapy (19.9% vs. 12.4%, p = 0.09). However, the need for mechanical circulatory support was similar in both groups. Patients with mottling at admission presented a higher length of stay (19 vs. 16 days, p = 0.033), a higher 30-day mortality rate (31% vs. 23.3%, p = 0.031), and also showed significantly higher mortality at 1-year (54% vs. 42%, p = 0.003). The subgroup of patients in whom mottling appeared during the first 24 h after admission had the worst prognosis at 30 days.

CONCLUSION

Skin mottling at admission in patients with cardiogenic shock was statistically associated with prolonged length of stay and poor outcomes. As a perfusion-targeted resuscitation parameter, mottling is a simple, clinical-based approach and may thus help to improve and guide immediate goal-directed therapy to improve cardiogenic shock patients' outcomes.

Microcirculatory dysfunction in cardiogenic shock

Cardiogenic shock is usually defined as primary cardiac dysfunction with low cardiac output leading to critical organ hypoperfusion, and tissue hypoxia, resulting in high mortality rate between 40% and 50% despite recent advances. Many studies have now evidenced that cardiogenic shock not only involves systemic macrocirculation, such as blood pressure, left ventricular ejection fraction, or cardiac output, but also involves significant systemic microcirculatory abnormalities which seem strongly associated with the outcome. Although microcirculation has been widely studied in the context of septic shock showing heterogeneous alterations with clear evidence of macro and microcirculation uncoupling, there is now a growing body of literature focusing on cardiogenic shock states. Even if there is currently no consensus regarding the treatment of microcirculatory disturbances in cardiogenic shock, some treatments seem to show a benefit. Furthermore, a better understanding of the underlying pathophysiology may provide hypotheses for future studies aiming to improve cardiogenic shock prognosis.

Pharmacological treatment of cardiogenic shock - A state of the art review

Cardiogenic shock is a clinical syndrome of impaired tissue perfusion caused by primary cardiac dysfunction and inadequate cardiac output. It represents one of the most lethal clinical conditions in intensive care medicine with mortality >40%. Management of different clinical presentations of cardiogenic shock includes guidance of cardiac preload, afterload, heart rate and contractility by differential pharmacological modulation of volume, systemic and pulmonary vascular resistance and cardiac output besides reversing the triggering cause. Data from large registries and randomized controlled trials on optimal diagnostic guidance as well as choice of pharmacological agents has accrued significantly in recent years. This state-of-the-art review summarizes the basic concepts of cardiogenic shock, the diagnostic work-up and currently available evidence and guideline recommendations on pharmacological treatment of cardiogenic shock.

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.

Early evaluation of organ failure using MELD-XI in critically ill elderly COVID-19 patients

PURPOSECritically ill elderly patients who suffer from Sars-CoV-2 disease are at high risk for organ failure. The modified MELD-XI score has not been evaluated for outcome prediction in these most vulnerable patients.METHODSThe Corona Virus disease (COVID19) in Very Elderly Intensive Care Patients study (COVIP, NCT04321265) prospectively recruited patients on intensive care units (ICU), who were = 70 years. Data were collected from March 2020 to February 2021. The MELD-XI score was calculated using the highest serum bilirubin and creatinine on ICU admission. Univariate and multivariable logistic regression analyses were performed to assess associations between the MELD-XI score and mortality. The primary outcome was 30-day-mortality, the secondary outcomes were ICU- and 3-month-mortality.RESULTSIn total, data from 2,993 patients were analyzed. Most patients had a MELD-XI <12 on admission (76%). The patients with MELD-XI = 12 had a significantly higher 30-day-, ICU- and 3-month-mortality (44%vs 64%, and 42%vs. 59%, and 57%vs. 76%, p < 0.001). After adjustment for multiple confounders, MELD-XI = 12 remained significantly associated with 30-day- (aOR 1.572, CI 1.268-1.949, p < 0.001), ICU-, and 3-month-mortality.CONCLUSIONIn critically ill elderly intensive care patients with COVID-19, the MELD-XI score constitutes a valuable tool for an early outcome prediction.

Präklinische Bluttransfusion bei lebensbedrohlicher Blutung – erweiterte lebensrettende Therapieoptionen durch das Konzept Medical Intervention Car

Das Medical Intervention Car (MIC) der Klinik für Anästhesiologie des Universitätsklinikums Heidelberg (UKHD) stellt ein neuartiges experimentelles Versorgungskonzept dar, welches zusätzliche Expertise und bisher nur innerklinisch etablierte Interventionen in der Präklinik verfügbar macht. Hierzu zählen die Transfusion von Blutprodukten, die Notfallthorakotomie, die „resuscitative endovascular balloon occlusion of the aorta“ (REBOA) sowie die Möglichkeit zur extrakorporalen kardiopulmonalen Reanimation (eCPR). Anhand der Fallvorstellung eines jungen Patienten, der sich mit einer Kettensäge in der Leiste verletzte und einen hämorrhagisch bedingten Kreislaufstillstand erlitt, wird insbesondere die Möglichkeit der lebensrettenden Transfusion diskutiert. In diesem Einsatz führte ein integratives präklinisches Versorgungskonzept, bestehend aus Rettungswagen, Notarzteinsatzfahrzeug und MIC, zur Wiederherstellung des Spontankreislaufs und einer vollständigen zerebralen Erholung des Patienten.

Experimental Myocardial Infarction Elicits Time-Dependent Patterns of Vascular Hypoxia in Peripheral Organs and in the Brain

Aims: Microvascular alterations occurring after myocardial infarction (MI) may represent a risk factor for multi-organ failure. Here we used in vivo photoacoustic (PA) imaging to track and define the changes in vascular oxygen saturation (sO₂) occurring over time after experimental MI in multiple peripheral organs and in the brain.

Methods and Results: Experimental MI was obtained in BALB/c mice by permanent ligation of the left anterior descending artery. PA imaging (Vevo LAZR-X) allowed tracking mouse-specific sO₂ kinetics in the cardiac left ventricular (LV) anterior wall, brain, kidney, and liver at 4 h, 1 day, and 7 days post-MI. Here we reported a correlation between LV sO₂ and longitudinal anterior myocardial strain after MI (r = −0.44, p < 0.0001, n = 96). Acute LV dysfunction was associated with global hypoxia, specifically a decrease in sO₂ level in the brain (−5.9%), kidney (−6.4%), and liver (−7.3%) at 4 and 24 h post-MI. Concomitantly, a preliminary examination of capillary NG2DsRed pericytes indicated cell rarefication in the heart and kidney. While the cardiac tissue was persistently impacted, sO₂ levels returned to pre-MI levels in the brain and in peripheral organs 7 days after MI.

Conclusions: Collectively, our data indicate that experimental MI elicits precise trajectories of vascular hypoxia in peripheral organs and in the brain. PA imaging enabled the synchronous tracking of oxygenation in multiple organs and occurring post-MI, potentially enabling a translational diagnostic modality for the identification of vascular modifications in this disease setting.

Evaluation of a shorter algorithm in an automated analysis of sublingual microcirculation

OBJECTIVE

Diagnostic and risk stratification in intensive and emergency medicine must be fast, accurate, and reliable. The assessment of sublingual microcirculation is a promising tool for this purpose. However, its value is limited because the measurement is time-consuming in unstable patients. This proof-of-concept validation study examines the non-inferiority of a reduced frame rate in image acquisition regarding quality, measurement results, and time.

METHODS

This prospective observational study included healthy volunteers. Sublingual measurement of microcirculation was performed using a sidestream dark field camera (SDF, MicroVision Medical®). Video-quality was evaluated with a modified MIQS (microcirculation image quality score). AVA 4.3C software calculated microcirculatory parameters.

RESULTS

Thirty-one volunteers were included. There was no impact of the frame rate on the time needed by the software algorithm to measure one video (4.5 ± 0.5 minutes) for AVA 4.3C. 86 frames per video provided non inferior video quality (MIQS 1.8 ± 0.7 for 86 frames versus MIQS 2.2 ± 0.6 for 215 frames, p < 0.05), equal results for all microcirculatory parameters, but did not result in an advantage in terms of speed. No complications occurred.

CONCLUSION

Video captures with 86 frames offer equal video quality and results for consensus parameters compared to 215 frames. However, there was no advantage regarding the time needed for the overall measurement procedure.

Sex-specific outcome disparities in very old patients admitted to intensive care medicine: a propensity matched analysis

Female and male very elderly intensive patients (VIPs) might differ in characteristics and outcomes. We aimed to compare female versus male VIPs in a large, multinational collective of VIPs with regards to outcome and predictors of mortality. In total, 7555 patients were included in this analysis, 3973 (53%) male and 3582 (47%) female patients. The primary endpoint was 30-day-mortality. Baseline characteristics, data on management and geriatric scores including frailty assessed by Clinical Frailty Scale (CFS) were documented. Two propensity scores (for being male) were obtained for consecutive matching, score 1 for baseline characteristics and score 2 for baseline characteristics and ICU management. Male VIPs were younger (83 ± 5 vs. 84 ± 5; p < 0.001), less often frail (CFS > 4; 38% versus 49%; p < 0.001) but evidenced higher SOFA (7 ± 6 versus 6 ± 6 points; p < 0.001) scores. After propensity score matching, no differences in baseline characteristics could be observed. In the paired analysis, the mortality in male VIPs was higher (mean difference 3.34% 95%CI 0.92–5.76%; p = 0.007) compared to females. In both multivariable logistic regression models correcting for propensity score 1 (aOR 1.15 95%CI 1.03–1.27; p = 0.007) and propensity score 2 (aOR 1.15 95%CI 1.04–1.27; p = 0.007) male sex was independently associated with higher odds for 30-day-mortality. Of note, male gender was not associated with ICU mortality (OR 1.08 95%CI 0.98–1.19; p = 0.14). Outcomes of elderly intensive care patients evidenced independent sex differences. Male sex was associated with adverse 30-day-mortality but not ICU-mortality. Further research to identify potential sex-specific risk factors after ICU discharge is warranted.

Trial registration: NCT03134807 and NCT03370692; Registered on May 1, 2017 https://clinicaltrials.gov/ct2/show/NCT03370692.

Sublingual microcirculation detects impaired perfusion in dehydrated older patients

BACKGROUND: Dehydration occurs frequently in older patients and constitutes a significant clinical problem. OBJECTIVE: This proof-of-concept study examines whether 1) sublingual measurement in dehydrated old patients is feasible, 2) frailty and incompliance in old, awake patients affects video-quality, 3) dehydration impacts microcirculation METHODS: This prospective observational study included clinically dehydrated patients aged ≥65 years immediately after admission. Dehydration was assessed clinically. A sidestream dark field camera (SDF) was used for measurement. Video-quality was evaluated with MIQS (microcirculation image quality score). Both AVA 4.3C- and AVA POEM-software analyzed the videos. Seventeen patients ≥65 years not showing dehydration served as control. RESULTS: Thirteen patients (8 female) were included. The average age was 83±8 years. The mini-mental test was 17±15 points, the Clinical Frailty Scale 4±3, the Barthel-Index 59±39. None of these parameters correlated with MIQS (3.4±4.2 SD (“acceptable”)). Dehydrated patients had a slightly impaired microcirculation, with a significantly lower percentage of perfused small vessels compared to control (83.1±7.7% versus 88.0±6.0%, P < 0.05). After rehydration, there was acute improvement in the microcirculation. CONCLUSIONS: Sublingual microcirculatory SDF-measurement is both, safe and valid for dehydrated old patients - regardless of frailty, age or cognitive performance. Dehydration leads to an impaired microcirculation.

Comprehensive Analysis of Macrocirculation and Microcirculation in Microgravity During Parabolic Flights

Background

Profound knowledge about cardiovascular physiology in the setting of microgravity can help in the course of preparations for human space missions. So far, influences of microgravity on the cardiovascular system have been demonstrated, particularly pertaining to venous fluid shifts. Yet, little is known about the mechanisms of these adaptations on continuous macrocirculatory level and regarding the microcirculation.

Methods

Twelve healthy volunteers were subjected to alternating microgravity and hypergravity in the course of parabolic flight maneuvers. Under these conditions, as well as in normal gravity, the sublingual microcirculation was assessed by intravital sidestream dark field microscopy. Furthermore, hemodynamic parameters such as heart rate, blood pressure, and cardiac output were recorded by beat-to-beat analysis. In these settings, data acquisition was performed in seated and in supine postures.

Results

Systolic [median 116 mmHg (102; 129) interquartile range (IQR) vs. 125 mmHg (109; 136) IQR, p = 0.01] as well as diastolic [median 72 mmHg (61; 79) IQR vs. 80 mmHg (69; 89) IQR, p = 0.003] blood pressure was reduced, and cardiac output [median 6.9 l/min (6.5; 8.8) IQR vs. 6.8 l/min (6.2; 8.5) IQR, p = 0.0002] increased in weightlessness compared to normal gravitation phases in the seated but not in the supine posture. However, microcirculation represented by perfused proportion of vessels and by total vessel density was unaffected in acute weightlessness.

Conclusion

Profound changes of the macrocirculation were found in seated postures, but not in supine postures. However, microcirculation remained stable in all postures.

[Evaluation of the microcirculation in critically ill patients : Relevance, practical possibilities and scientific evidence]

Für die Aufrechterhaltung der Organdurchblutung ist eine intakte Makro- und Mikrozirkulation essentiell. Sowohl das wachsende Verständnis um die Bedeutung der Mikrozirkulation im Organversagen als auch die Möglichkeit, diese zu visualisieren, lenken die Aufmerksamkeit der Intensivmedizin auf die mikrovaskuläre Endstrombahn. Als Surrogat-Parameter sind die Rekapillarisierungszeit, der „mottling score“ und die Messung des Serum-Laktats bereits lange in der klinischen Praxis etabliert. Neuere Studien messen der Echtzeit-Darstellung der sublingualen Mikrozirkulation mittels Intravital-Videomikroskopie eine immer größere Bedeutung bei. Verschiedene Studien unterstreichen hierbei die Mikrozirkulation als prognostischen Parameter. Darüber hinaus ermöglicht die Erhebung von objektivierbaren Messwerten, diese in der Zukunft zur individuellen Therapiesteuerung weitergehend zu untersuchen.

Sublingual microcirculation in prehospital critical care medicine: A proof-of-concept study

OBJECTIVE

Diagnostic and risk stratification are limited in emergencies. The measurement of microcirculation might identify patients with poor perfusion but compensated macrocirculation such as in beginning shock. This proof-of-concept study examines whether sublingual prehospital sidestream dark-field microscopy is feasible.

METHODS

This prospective observational study included patients receiving medical aid by an emergency ambulance who had a spontaneous circulation and offered access to the sublingual mucosa. Sublingual measurement of microcirculation was performed using a sidestream dark field camera. Video quality was evaluated with microcirculation image quality score (microcirculation image quality score). AVA 4.3C software calculated microcirculatory parameters.

RESULTS

Thirty patients (47% male) were included. The average age was 63 years (±20 years SD), the severity of the disease (quantified by National Advisory Committee on Aeronautics) was 3.4 (±0.7 SD). Macrocirculation presented within the normal range. The most frequent cause preventing the measurement was a time-critical disease (64%). In 17 patients (57%), the videos could be analyzed immediately. The average quality of the video was 2.2 ± 0.45 points ('acceptable'). There were minor restrictions of microcirculation. Microcirculation correlated with National Advisory Committee on Aeronautics, but not with the macrocirculation. No complications occurred.

CONCLUSION

The prehospital sublingual measurement is safe and valid. Despite normal macrocirculation, microcirculation was impaired and correlated with National Advisory Committee on Aeronautics.

Cardiogenic Shock: Reflections at the Crossroad Between Perfusion, Tissue Hypoxia, and Mitochondrial Function

Cardiogenic shock is classically defined by systemic hypotension with evidence of hypoperfusion and end organ dysfunction. In modern practice, however, these metrics often incompletely describe cardiogenic shock because patients present with more advanced cardiovascular disease and greater degrees of multiorgan dysfunction. Understanding how perfusion, congestion, and end organ dysfunction contribute to hypoxia at the cellular level are central to the diagnosis and management of cardiogenic shock. Although, in clinical practice, increased lactate level is often equated with hypoxia, several other factors might contribute to an elevated lactate level including mitochondrial dysfunction, impaired hepatic and renal clearance, as well as epinephrine use. To this end, we present the evidence underlying the value of lactate to pyruvate ratio as a potential discriminator of cellular hypoxia. We will then discuss the physiological implications of hypoxia and congestion on hepatic, intestinal, and renal physiology. Organ-specific susceptibility to hypoxia is presented in the context of their functional architecture. We discuss how the concepts of contractile reserve, fluid responsiveness, tissue oxygenation, and cardiopulmonary interactions can help personalize the management of cardiogenic shock. Finally, we highlight the limitations of using lactate for tailoring therapy in cardiogenic shock.