Modified Gott shunt to avoid left ventricular overload and cerebral hypoperfusion during distal aortic arch surgery

We present a simple solution to address—at the same time—the issue of spinal perfusion, overload on the left ventricle, and brain perfusion during complex distal arch and descending aortic surgery. It is a modification of a passive Gott shunt that includes an extra 10-mm tube interposed between the side port of the ascending aorta cannula and the left subclavian artery. This technique may represent an extra option for surgeons during complex aortic surgery to maintain satisfactory distal perfusion, to reduce the cardiac load, and to provide adequate perfusion to the brain

Spectral-profile-based algorithm for hemoglobin oxygen saturation determination from diffuse reflectance spectra

Variations of hemoglobin (Hb) oxygenation in tissue provide important indications concerning the physiological conditions of tissue, and the data related to these variations are of intense interest in medical research as well as in clinical care. In this study, we derived a new algorithm to estimate Hb oxygenation from diffuse reflectance spectra. The algorithm was developed based on the unique spectral profile differences between the extinction coefficient spectra of oxy-Hb and deoxy-Hb within the visible wavelength region. Using differential wavelet transformation, these differences were quantified using the locations of certain spectral features, and, then, they were related to the oxygenation saturation level of Hb. The applicability of the algorithm was evaluated using a set of diffuse reflectance spectra produced by a Monte Carlo simulation model of photon migration and by tissue phantoms experimentally. The algorithm was further applied to the diffuse reflectance spectra acquired from in vivo experiments to demonstrate its clinical utility. The validation and evaluation results concluded that the algorithm is applicable to various tissue types (i.e., scattering properties) and can be easily used in conjunction with a diverse range of probe geometries for real-time monitoring of Hb oxygenation

Monitoring of the Sublingual Microcirculation During Cardiac Surgery:Current Knowledge and Future Directions

Handheld vital microscopes allow for direct observation of the sublingual microcirculatory perfusion during cardiac surgery. Through the use of handheld vital microscopes, it has been shown that cardiac surgery with cardiopulmonary bypass is associated with reduced and heterogenous microcirculatory perfusion. Microcirculatory impairment can result in inadequate tissue perfusion, leading to perioperative complications and poor outcome. Because microcirculatory impairment can occur despite stable or improved global hemodynamics, there is a yet unmet need for specific monitoring of the microcirculation. Technological advancements may facilitate point-of-care monitoring of microcirculatory perfusion using automated real-time analysis of microcirculatory measurements. Thus, microcirculatory monitoring may create new opportunities for specific microcirculatory treatment as part of hemodynamic management. The implementation of microcirculatory variables into personalized treatment concepts has the potential to improve hemodynamic management during cardiac surgery and thereby improve patient outcomes. Therefore, specific treatment strategies need to be developed to prevent or treat alterations of the microcirculatory perfusion. In the future, the use of handheld vital microscopes for microcirculatory monitoring may help to improve hemodynamic management and outcomes for patients undergoing cardiac surgical procedures

A Floating Thrombus Anchored at the Proximal Anastomosis of a Woven Thoracic Graft Mimicking a Genuine Aortic Dissection

An aortoesophageal fistula following surgery for a ruptured 6.6-cm thoracic aneurysm in a 69-yearold female was repaired using a 34-mm woven prosthetic graft. A follow-up computed tomography (CT) scan at 10 days postoperatively revealed a dissection-like picture in the region of the graft, which was treated conservatively. The patient eventually died from sepsis and multiorgan failure. At autopsy, the graft was retrieved in situ and studied by detailed gross, microscopy, and scanning electron microscopy (SEM) examination. Gross observation confirmed that the dissection resulted from the rolling of the internal capsule downstream. A massive thrombus anchored at the proximal anastomosis and held by a narrow head was also noted. The thrombus demonstrated reorganization in the area of the anastomosis, with a false lumen in its distal half. The reminder of the thrombus consisted of layered fibrin. After gross examination, the fabric graft was found to be flawless. Additional detailed studies were also done using microscopy, SEM, and gross examination

Bedside Sublingual Video Imaging of Microcirculation in Assessing Bacterial Infection in Cirrhosis

Bacterial infections are common in cirrhosis and can lead to life-threatening complications. Sidestream dark-field (SDF) imaging has recently emerged as a noninvasive tool for capturing real-time video images of sublingual microcirculation in critically ill patients with sepsis. The objective of this study was to assess the utility of SDF in determining underlying infection in patients with cirrhosis. Sublingual microcirculation was compared among patients with compensated cirrhosis (Group A, n = 13), cirrhosis without sepsis (Group B, n = 18), cirrhosis with sepsis (Group C, n = 14), and sepsis only (Group D, n = 10). The blood flow was semi-quantitatively evaluated in four equal quadrants in small (10–25 mm); medium (26–50 mm); and large (51–100 mm) sublingual capillaries. The blood flow was described as no flow (0), intermittent flow (1), sluggish flow (2), and continuous flow (3). The overall flow score or microvascular flow index (MFI) was measured for quantitative assessment of microcirculation and predicting power for concurrent infection in cirrhosis. Marked impairment was observed at all levels of microvasculature in Groups B and C when compared with Group A. This effect was restricted to small vessels only when Group B was compared with Group C. MFI < 1.5 was found to have highest sensitivity (100%) and specificity (100%) for infection in decompensated cirrhosis. SDF imaging of sublingual microcirculation can be a useful bedside diagnostic tool to assess bacterial infection in cirrhosis

Microcirculatory alterations: potential mechanisms and implications for therapy

Multiple experimental and human trials have shown that microcirculatory alterations are frequent in sepsis. In this review, we discuss the characteristics of these alterations, the various mechanisms potentially involved, and the implications for therapy. Sepsis-induced microvascular alterations are characterized by a decrease in capillary density with an increased number of stopped-flow and intermittent-flow capillaries, in close vicinity to well-perfused capillaries. Accordingly, the surface available for exchange is decreased but also is highly heterogeneous. Multiple mechanisms may contribute to these alterations, including endothelial dysfunction, impaired inter-cell communication, altered glycocalyx, adhesion and rolling of white blood cells and platelets, and altered red blood cell deformability. Given the heterogeneous nature of these alterations and the mechanisms potentially involved, classical hemodynamic interventions, such as fluids, red blood cell transfusions, vasopressors, and inotropic agents, have only a limited impact, and the microcirculatory changes often persist after resuscitation. Nevertheless, fluids seem to improve the microcirculation in the early phase of sepsis and dobutamine also can improve the microcirculation, although the magnitude of this effect varies considerably among patients. Finally, maintaining a sufficient perfusion pressure seems to positively influence the microcirculation; however, which mean arterial pressure levels should be targeted remains controversial. Some trials using vasodilating agents, especially nitroglycerin, showed promising initial results but they were challenged in other trials, so it is difficult to recommend the use of these agents in current practice. Other agents can markedly improve the microcirculation, including activated protein C and antithrombin, vitamin C, or steroids. In conclusion, microcirculatory alterations may play an important role in the development of sepsis-related organ dysfunction. At this stage, therapies to target microcirculation specifically are still being investigated