Microcirculatory dysfunction and dead-space ventilation in early ARDS: a hypothesis-generating observational study - 08/01/26
, Diego F. Bautista 1, Humberto J. Madriñán 1, Juan D. Valencia 1, William F. Bermúdez 1, Edgardo Quiñones 1, Luis Eduardo Calderón-Tapia 1, Glenn Hernandez 3, Alejandro Bruhn 3, Daniel De Backer 4
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Abstract |
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 CO 2 production ( 
) and CO 2 exhaled fraction ( 
) 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.
Le texte complet de cet article est disponible en PDF.Keywords : Acute respiratory distress syndrome, Dead-space ventilation, V D /V T, Ventilation/perfusion mismatch, Microcirculation, Microcirculatory blood flow
Plan
Vol 10 - N° 1
Article 35- 2020 Retour au numéro
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