No abstract

Parameters related to macrocirculation, such as the mean arterial pressure, central venous pressure, cardiac output, mixed venous saturation and central oxygen saturation, are commonly used in the hemodynamic assessment of critically ill patients. However, several studies have shown that there is a dissociation between these parameters and the state of microcirculation in this group of patients. Techniques that allow direct viewing of the microcirculation are not completely disseminated, nor are they incorporated into the clinical management of patients in shock. The numerous techniques developed for microcirculation assessment include clinical assessment (e.g., peripheral perfusion index and temperature gradient), laser Doppler flowmetry, tissue oxygen assessment electrodes, videomicroscopy (orthogonal polarization spectral imaging, sidestream dark field imaging or incident dark field illumination) and near infrared spectroscopy. In the near future, the monitoring and optimization of tissue perfusion by direct viewing and microcirculation assessment may become a goal to be achieved in the hemodynamic resuscitation of critically ill patients.

Background Transfusion of blood components prior to invasive procedures in cirrhosis patients is high and associated with adverse events. Objectives We compared three transfusion strategies prior to central venous catheterization in cirrhosis patients. Patients/Methods Single center randomized trial that included critically ill cirrhosis patients with indication for central venous line in a tertiary private hospital in Brazil. Interventions: Restrictive protocol, thromboelastometry‐guided protocol, or usual care (based on coagulogram). The primary endpoint was the proportion of patients transfused with any blood component (ie, fresh frozen plasma, platelets, or cryoprecipitate). The secondary endpoints included incidence of bleeding and transfusion‐related adverse events. Results A total of 57 patients (19 per group; 64.9% male; mean age, 53.4 ± 11.3 years) were enrolled. Prior to catheterization, 3/19 (15.8%) in the restrictive arm, 13/19 (68.4%) in the thromboelastometry‐guided arm, and 14/19 (73.7%) in the coagulogram‐guided arm received blood transfusion (odds ratio [OR], 0.07; 95% confidence interval [CI], 0.01‐0.45; P = .002 for restrictive versus coagulogram‐guided arm; OR, 0.09; 95% CI, 0.01‐0.56; P = .006 for restrictive versus thromboelastometry‐guided arm; and OR, 0.77; 95% CI, 0.14‐4.15; P = .931 for thromboelastometry‐guided versus coagulogram‐guided arm). The restrictive protocol was cost saving. No difference in bleeding, length of stay, mortality, and transfusion‐related adverse events was found. Conclusions The use of a restrictive strategy is associated with a reduction in transfusion prior to central venous catheterization and costs in critically ill cirrhosis patients. No effect on bleeding was found among the groups.

Patients who increase stoke volume or cardiac index more than 10 or 15% after a fluid challenge are usually considered fluid responders. Assessment of fluid responsiveness prior to volume expansion is critical to avoid fluid overload, which has been associated with poor outcomes. Maneuvers to assess fluid responsiveness are well established in mechanically ventilated patients; however, few studies evaluated maneuvers to predict fluid responsiveness in spontaneously breathing patients. Our objective was to perform a systematic review of literature addressing the available methods to assess fluid responsiveness in spontaneously breathing patients. Studies were identified through electronic literature search of PubMed from 01/08/2009 to 01/08/2016 by two independent authors. No restrictions on language were adopted. Quality of included studies was evaluated with Quality Assessment of Diagnostic Accuracy Studies tool. Our search strategy identified 537 studies, and 9 studies were added through manual search. Of those, 15 studies (12 intensive care unit patients; 1 emergency department patients; 1 intensive care unit and emergency department patients; 1 operating room) were included in this analysis. In total, 649 spontaneously breathing patients were assessed for fluid responsiveness. Of those, 340 (52%) were deemed fluid responsive. Pulse pressure variation during the Valsalva maneuver (∆PPV) of 52% (AUC ± SD: 0.98 ± 0.03) and passive leg raising-induced change in stroke volume (∆SV-PLR) > 13% (AUC ± SD: 0.96 ± 0.03) showed the highest accuracy to predict fluid responsiveness in spontaneously breathing patients. Our systematic review indicates that regardless of the limitations of each maneuver, fluid responsiveness can be assessed in spontaneously breathing patients. Further well-designed studies, with adequate simple size and power, are necessary to confirm the real accuracy of the different methods used to assess fluid responsiveness in this population of patients.

Microvascular dysfunction has been associated with adverse outcomes in critically ill patients, and the current concept of hemodynamic incoherence has gained attention. Our objective was to perform a comprehensive analysis of microcirculatory perfusion parameters and to investigate the best variables that could discriminate patients with and without circulatory shock during early intensive care unit (ICU) admission. This prospective observational study comprised a sample of 40 adult patients with and without circulatory shock (n = 20, each) admitted to the ICU within 24 h. Peripheral clinical [capillary refill time (CRT), peripheral perfusion index (PPI), skin-temperature gradient (Tskin-diff)] and laboratory [arterial lactate and base excess (BE)] perfusion parameters, in addition to near-infrared spectroscopy (NIRS)-derived variables were simultaneously assessed. While lactate, BE, CRT, PPI and Tskin-diff did not differ significantly between the groups, shock patients had lower baseline tissue oxygen saturation (StO 2 ) [81 (76-83) % vs. 86 (76-90) %, p = 0.044], lower StO 2 min [50 (47-57) % vs. 55 (53-65) %, p = 0.038] and lower StO 2 max [87 (80-92) % vs. 93 (90-95) %, p = 0.017] than patients without shock. Additionally, dynamic NIRS variables [recovery time (r = 0.56, p = 0.010), descending slope (r = − 0.44, p = 0.05) and ascending slope (r = − 0.54, p = 0.014)] and not static variable [baseline StO 2 (r = − 0.24, p = 0.28)] exhibited a significant correlation with the administered dose of norepinephrine. In our study with critically ill patients assessed within the first twenty-four hours of ICU admission, among the perfusion parameters, only NIRS-derived parameters could discriminate patients with and without shock.