Impact of increased mean arterial pressure on skin microcirculatory oxygenation in vasopressor-requiring septic patients : an interventional study

Background: Heterogeneity of microvascular blood flow leading to tissue hypoxia is a common finding in patients with septic shock. It may be related to suboptimal systemic perfusion pressure and lead to organ failure. Mapping of skin microcirculatory oxygen saturation and relative hemoglobin concentration using hyperspectral imaging allows to identify heterogeneity of perfusion and perform targeted measurement of oxygenation. We hypothesized that increasing mean arterial pressure would result in improved oxygenation in areas of the skin with most microvascular blood pooling. Methods: We included adult patients admitted to the intensive care unit within the previous 24 h with sepsis and receiving a noradrenaline infusion. Skin oxygen saturation was measured using hyperspectral imaging-based method at baseline and after the increase in mean arterial pressure by 20 mm Hg by titration of noradrenaline doses. The primary outcome was an increase in skin oxygen saturation depending upon disease severity. Results: We studied 30 patients with septic shock. Median skin oxygen saturation changed from 26.0 (24.5–27.0) % at baseline to 30.0 (29.0–31.0) % after increase in mean arterial pressure (p=0.04). After adjustment for baseline saturation, patients with higher SOFA scores achieved higher oxygen saturation after the intervention (r2=0.21; p=0.02). Skin oxygen saturation measured at higher pressure was found to be marginally predictive of mortality (OR: 1.10; 95% CI 1.00–1.23; p=0.053). Conclusions: Improvement of microcirculatory oxygenation can be achieved with an increase in mean arterial pressure in most patients. Response to study intervention is proportional to disease severity.publishersversionPeer reviewe

Quantitative assessment of the microcirculation in healthy volunteers and in patients with septic shock

Objective: The microcirculation of septic patients has been characterized only semiquantitatively. Our goal was to characterize the sublingual microcirculation in healthy volunteers and patients with septic shock quantitatively. Our hypotheses were that 1) hyperdynamic blood flow is absent in septic shock; 2) nonsurvivors show more severe alterations than survivors; and 3) quantitative and semiquantitative microcirculatory parameters have a similar performance. Design: Prospective, observational study. Setting: Teaching intensive care unit in a university-affiliated hospital. Subjects: Twenty-five normal volunteers and 25 patients with septic shock. Interventions: None. Measurements and Main Results: The sublingual microcirculation was evaluated by means of sidestream dark field imaging. Semiquantitative and quantitative microcirculatory parameters were determined through the use of applied software. Septic patients showed decreased perfused capillary density (13.2 +/- 4.4 mm/mm(2) vs. 16.6 +/- 1.6 mm/mm(2)), proportion of perfused capillaries (0.78 +/- 0.23 vs. 1.00 +/- 0.01), microvascular flow index (2.15 +/- 0.61 vs. 2.97 +/- 0.03), and red blood cell veloc Conclusions: The main characteristics of sublingual microcirculation in patients with septic shock are hypoperfusion and increased flow heterogeneity. Hyperdynamic microvascular blood flow was not found. Nonsurvivors showed more severe alterations than survivors. Quantitative and semiquantitative microcirculatory variables displayed similar behaviors. (Crit Care Med 2012; 40: 1443-1448

Monitoring tissue perfusion: a pilot clinical feasibility and safety study of a urethral photoplethysmography-derived perfusion device in high-risk patients

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