Microcirculatory blood flow derangements during severe preeclampsia and HELLP syndrome

Objective To evaluate the microcirculatory blood flow in severe preeclampsia and compare it with healthy pregnant and non-pregnant women controls, using a portable intravital-microscopy technique. Methods Using a side-stream dark field (SDF) device, we prospectively evaluated the sublingual microcirculatory blood flow before placental delivery in 40 women with severe preeclampsia (PE-group) complicated (n = 8) or not (n = 32) with HELLP syndrome, 40 healthy pregnant women (HP-group) matched by gestational and chronological age, and 20 healthy non-pregnant women (NP-group). Microvessels were classified as large or small using a cutoff value of 20 μm and those with continuous flow were considered as normal while sluggish, intermittent and stopped flows were considered as abnormal. We computed the proportion of well-perfused small vessels (PPV), and total and functional capillary densities (TCD and FCD) were calculated according to the total number and quantity of well-perfused small vessels per area unit, respectively. Results Total capillary densities were significantly higher in all pregnant women when compared to non-pregnant controls. The PE-group exhibited, however, significantly lower TCD compared with the HP-group. Meanwhile, significant decreases in PPV and FCD were observed in the PE-group, with deeper alterations in those with coexisting HELLP syndrome. These altered PPVs were significant although incompletely reversed after placental delivery in pregnancies complicated by HELLP syndrome, while capillary densities remained unaltered at least during very early post-delivery period. Conclusions Substantial distributive microcirculatory blood flow alterations and restricted capillary densities are observed in preeclampsia, suggesting a key role for microvascular dysfunction in the pathophysiology of this condition.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Microcirculatory dysfunction and dead-space ventilation in early ARDS: a hypothesis-generating observational study

Background: Ventilation/perfusion inequalities impair gas exchange in acute respiratory distress syndrome (ARDS). Although increased dead-space ventilation (VD/VT) has been described in ARDS, its mechanism is not clearly understood. We sought to evaluate the relationships between dynamic variations in VD/VT and extra-pulmonary microcirculatory blood flow detected at sublingual mucosa hypothesizing that an altered microcirculation, which is a generalized phenomenon during severe inflammatory conditions, could influence ventilation/perfusion mismatching manifested by increases in VD/VT fraction during early stages of ARDS. Methods: Forty-two consecutive patients with early moderate and severe ARDS were included. PEEP was set targeting the best respiratory-system compliance after a PEEP-decremental recruitment maneuver. After 60 min of stabilization, hemodynamics and respiratory mechanics were recorded and blood gases collected. VD/VT was calculated from the CO2 production (VCO2) and CO2 exhaled fraction (FECO2) measurements by volumetric capnography. Sublingual microcirculatory images were simultaneously acquired using a sidestream dark-field device for an ulterior blinded semi-quantitative analysis. All measurements were repeated 24 h after. Results: Percentage of small vessels perfused (PPV) and microcirculatory flow index (MFI) were inverse and significantly related to VD/VT at baseline (Spearman’s rho = − 0.76 and − 0.63, p < 0.001; R2 = 0.63, and 0.48, p < 0.001, respectively) and 24 h after (Spearman’s rho = − 0.71, and − 0.65; p < 0.001; R2 = 0.66 and 0.60, p < 0.001, respectively). Other respiratory, macro-hemodynamic and oxygenation parameters did not correlate with VD/VT. Variations in PPV between baseline and 24 h were inverse and significantly related to simultaneous changes in VD/VT (Spearman’s rho = − 0.66, p < 0.001; R2 = 0.67, p < 0.001). Conclusion: Increased heterogeneity of microcirculatory blood flow evaluated at sublingual mucosa seems to be related to increases in VD/VT, while respiratory mechanics and oxygenation parameters do not. Whether there is a cause–effect relationship between microcirculatory dysfunction and dead-space ventilation in ARDS should be addressed in future research.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

0032. Relationship between microcirculatory alterations and venous-to-arterial carbon dioxide differences in patients with septic shock

SCOPUS: no.jinfo:eu-repo/semantics/publishe

Can venous-to-arterial carbon dioxide differences reflect microcirculatory alterations in patients with septic shock?

Purpose: Septic shock has been associated with microvascular alterations and these in turn with the development of organ dysfunction. Despite advances in video microscopic techniques, evaluation of microcirculation at the bedside is still limited. Venous-to-arterial carbon dioxide difference (Pv-aCO2) may be increased even when venous O2 saturation (SvO2) and cardiac output look normal, which could suggests microvascular derangements. We sought to evaluate whether Pv-aCO2 can reflect the adequacy of microvascular perfusion during the early stages of resuscitation of septic shock. Methods: Prospective observational study including 75 patients with septic shock in a 60-bed mixed ICU. Arterial and mixed-venous blood gases and hemodynamic variables were obtained at catheter insertion (T0) and 6 h after (T6). Using a sidestream dark-field device, we simultaneously acquired sublingual microcirculatory images for blinded semiquantitative analysis. Pv-aCO2 was defined as the difference between mixed-venous and arterial CO2 partial pressures. Results: Progressively lower percentages of small perfused vessels (PPV), lower functional capillary density, and higher heterogeneity of microvascular blood flow were observed at higher Pv-aCO2 values at both T0 and T6. Pv-aCO2 was significantly correlated to PPV (T0: coefficient −5.35, 95 % CI −6.41 to −4.29, p < 0.001; T6: coefficient, −3.49, 95 % CI −4.43 to −2.55, p < 0.001) and changes in Pv-aCO2 between T0 and T6 were significantly related to changes in PPV (R2 = 0.42, p < 0.001). Absolute values and changes in Pv-aCO2 were not related to global hemodynamic variables. Good agreement between venous-to-arterial CO2 and PPV was maintained even after corrections for the Haldane effect. Conclusions: During early phases of resuscitation of septic shock, Pv-aCO2 could reflect the adequacy of microvascular blood flow.SCOPUS: ar.jinfo:eu-repo/semantics/publishe