Sepsis and septic shock

Hand-held vital microscopes (HVMs) were introduced to observe sublingual microcirculatory alterations at the bedside in different shock states in critically ill patients This consensus aims to provide clinicians with guidelines for practical use and interpretation of the sublingual microcirculation Furthermore, it aims to promote the integration of routine application of HVM microcirculatory monitoring in conventional hemodynamic monitoring of systemic hemodynamic variables In accordance with the Delphi method we organized three international expert meetings to discuss the various aspects of the technology, physiology, measurements, and clinical utility of HVM sublingual microcirculatory monitoring to formulate this consensus document A task force from the Cardiovascular Dynamics Section of the European Society of Intensive Care Medicine (with endorsement of its Executive Committee) created this consensus as an update of a previous consensus in 2007 We classified consensus statements as definitions, requirements, and/or recommendations, with a minimum requirement of 80% agreement of all participants In this consensus the nature of microcirculatory alterations is described The nature of variables, which can be extracted from analysis of microcirculatory images, is presented and the needed dataset of variables to identify microcirculatory alterations is defined Practical aspects of sublingual HVM measurements and the nature of artifacts are described Eleven statements were formulated that pertained to image acquisitions and quality statements Fourteen statements addressed the analysis of the images, and 13 statements are related to future developments This consensus describes 25 statements regarding the acquisition and interpretation of microcirculatory images needed to guide the assessment of the microcirculation in critically ill patients

/pdf/second-consensus-on-the-assessment-of-sublingual-1frhv9kbro.pdf

Second consensus on the assessment of sublingual microcirculation in critically ill patients: results from a task force of the European Society of Intensive Care Medicine

Sufficient organ perfusion essentially depends on preserved macro- and micro-circulation. The last two decades brought substantial progress in the development of less and non-invasive monitoring of macro-hemodynamics. However, several recent studies suggest a frequent incoherence of macro- and micro-circulation. Therefore, this review reports on interactions of macro- and micro-circulation as well as on specific regional and micro-circulation. Regarding global micro-circulation the last two decades brought advances in a more systematic approach of clinical examination including capillary refill time, a graded assessment of mottling of the skin and accurate measurement of body surface temperatures. As a kind of link between macro- and microcirculation, a number of biochemical markers can easily be obtained. Among those are central-venous oxygen saturation (ScvO2), plasma lactate and the difference between central-venous and arterial CO2 (cv-a-pCO2-gap). These inexpensive markers have become part of clinical routine and guideline recommendations. While their potential to replace parameters of macro-circulation such as cardiac output (CO) is limited, they facilitate the interpretation of the adequacy of CO and other macro-circulatory markers. Furthermore, they give additional hints on micro-circulatory impairment. In addition, a number of more sophisticated technical approaches to quantify and visualize micro-circulation including video-microscopy, laser flowmetry, near-infrared spectroscopy (NIRS), and partial oxygen pressure measurement have been introduced within the last 20 years. These technologies have been extensively used for scientific purposes. Moreover, they have been successfully used for educational purposes and to visualize micro-circulatory disturbances during sepsis and other causes of shock. Despite several studies demonstrating the association of these techniques and parameters with outcome, their practical application still is limited. However, future improvements in automated and "online" diagnosis will help to make these technologies more applicable in clinical routine. This approach is promising with regard to several studies which demonstrated the potential to guide therapy in different types of shock. Finally several organs have specific patterns of circulation related to their special anatomy (liver) or their auto-regulatory capacities (brain, kidney). Therefore, this review also discusses specific issues of monitoring liver, brain, and kidney circulation and function.

/pdf/assessment-of-regional-perfusion-and-organ-function-less-and-b0wfuthl0b.pdf

Assessment of Regional Perfusion and Organ Function: Less and Non-invasive Techniques.

The availability of handheld, noninvasive sublingual video-microscopes allows for visualization of the microcirculation in critically ill patients. Recent studies demonstrate that reduced numbers of blood-perfused microvessels and increased penetration of erythrocytes into the endothelial glycocalyx are essential components of microvascular dysfunction. The aim of this study was to identify novel microvascular variables to determine the level of microvascular dysfunction in sepsis and its relationship with clinical variables. This observational, prospective, cross-sectional study included 51 participants, of which 34 critically ill sepsis patients were recruited from intensive care units of a university hospital. Seventeen healthy volunteers served as controls. All participants underwent sublingual videomicroscopy by sidestream darkfield imaging. A new developed version of the Glycocheck™ software was used to quantify vascular density, perfused boundary region (PBR-an inverse variable of endothelial glycocalyx dimensions), red blood cell (RBC) velocity, RBC content, and blood flow in sublingual microvessels with diameters between 4 and 25 µm. A detailed analysis of adjacent diameter classes (1 µm each) of vessels between 4 and 25 µm revealed a severe reduction of vascular density in very small capillaries (5–7 µm), which correlated with markers of sepsis severity. Analysis of RBC velocity (VRBC) revealed a strong dependency between capillary and feed vessel VRBC in sepsis patients (R2 = 0.63, p < 0.0001) but not in healthy controls (R2 = 0.04, p = 0.43), indicating impaired capillary (de-)recruitment in sepsis. This finding enabled the calculation of capillary recruitment and dynamic capillary blood volume (CBVdynamic). Moreover, adjustment of PBR to feed vessel VRBC further improved discrimination between sepsis patients and controls by about 50%. By combining these dynamic microvascular and glycocalyx variables, we developed the microvascular health score (MVHSdynamic™), which decreased from 7.4 [4.6–8.7] in controls to 1.8 [1.4–2.7] in sepsis patients (p < 0.0001) and correlated with sepsis severity. We introduce new important diameter-specific quantification and differentiated analysis of RBC kinetics, a key to understand microvascular dysfunction in sepsis. MVHSdynamic, which has a broad bandwidth to detect microvascular (dys-) function, might serve as a valuable tool to detect microvascular impairment in critically ill patients.

/pdf/identification-of-novel-sublingual-parameters-to-analyze-and-19h0qheh8q.pdf

Identification of novel sublingual parameters to analyze and diagnose microvascular dysfunction in sepsis: the NOSTRADAMUS study

Canadian Journal of Physiology and Pharmacology. Introduction.

Analysis of the microcirculation is currently performed offline, is time consuming and operator dependent. The aim of this study was to assess the ability and efficiency of the automatic analysis software CytoCamTools 1.7.12 (CC) to measure microvascular parameters in comparison with Automated Vascular Analysis (AVA) software 3.2. 22 patients admitted to the cardiothoracic intensive care unit following cardiac surgery were prospectively enrolled. Sublingual microcirculatory videos were analysed using AVA and CC software. The total vessel density (TVD) for small vessels, perfused vessel density (PVD) and proportion of perfused vessels (PPV) were calculated. Blood flow was assessed using the microvascular flow index (MFI) for AVA software and the averaged perfused speed indicator (APSI) for the CC software. The duration of the analysis was also recorded. Eighty-four videos from 22 patients were analysed. The bias between TVD-CC and TVD-AVA was 2.20 mm/mm2 (95 % CI 1.37–3.03) with limits of agreement (LOA) of −4.39 (95 % CI −5.66 to −3.16) and 8.79 (95 % CI 7.50–10.01) mm/mm2. The percentage error (PE) for TVD was ±32.2 %. TVD was positively correlated between CC and AVA (r = 0.74, p < 0.001). The bias between PVD-CC and PVD-AVA was 6.54 mm/mm2 (95 % CI 5.60–7.48) with LOA of −4.25 (95 % CI −8.48 to −0.02) and 17.34 (95 % CI 13.11–21.57) mm/mm2. The PE for PVD was ±61.2 %. PVD was positively correlated between CC and AVA (r = 0.66, p < 0.001). The median PPV-AVA was significantly higher than the median PPV-CC [97.39 % (95.25, 100 %) vs. 81.65 % (61.97, 88.99), p < 0.0001]. MFI categories cannot estimate or predict APSI values (p = 0.45). The time required for the analysis was shorter with CC than with AVA system [2′42″ (2′12″, 3′31″) vs. 16′12″ (13′38″, 17′57″), p < 0.001]. TVD is comparable between the two softwares, although faster with CC software. The values for PVD and PPV are not interchangeable given the different approach to assess microcirculatory flow.

Ability and efficiency of an automatic analysis software to measure microvascular parameters

Shock is defined as a state in which the circulation is unable to deliver sufficient oxygen to meet the demands of the tissues, resulting in cellular dysoxia and organ failure. In this process, the factors that govern the circulation at a haemodynamic level and oxygen delivery at a microcirculatory level play a major role. This manuscript aims to review the blood flow regulation from macro- and micro-haemodynamic point of view and to discuss new potential therapeutic approaches for cardiovascular instability in patients in cardiovascular shock. Despite the recent advances in haemodynamics, the mechanisms that control the vascular resistance and the venous return are not fully understood in critically ill patients. The physical properties of the vascular wall, as well as the role of the mean systemic filling pressure are topics that require further research. However, the haemodynamics do not totally explain the physiopathology of cellular dysoxia, and several factors such as inflammatory changes at the microcirculatory level can modify vascular resistance and tissue perfusion. Cellular vasoactive mediators and endothelial and glucocalix damage are also involved in microcirculatory impairment. All the levels of the circulatory system must be taken into account. Evaluation of microcirculation may help one to detect under-diagnosed shock, and together with classic haemodynamics, guide one towards the appropriate therapy. Restoration of classic haemodynamic parameters is essential but not sufficient to detect and treat patients in cardiovascular shock.

/pdf/from-cardiac-output-to-blood-flow-auto-regulation-in-shock-2im4fw0lda.pdf

From cardiac output to blood flow auto-regulation in shock

Analysis of microvascular density parameters is time consuming and operator-dependent.1 This is the main limitation to use microvascular monitoring in clinical practice as a “point-of-care” tool. Recently, an automatic analysis software has been developed and could allow us to obtain results quickly.

/pdf/accuracy-of-an-automatic-analysis-software-to-detect-452vadbqzl.pdf

Accuracy of an automatic analysis software to detect microvascular density parameters

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Ability and efficiency of an automatic analysis software to measure microvascular parameters

From cardiac output to blood flow auto-regulation in shock

Accuracy of an automatic analysis software to detect microvascular density parameters