Abstract 176: Assessment of Sublingual Microcirculation by Sidestream Darkfield Imaging: A Word of Caution

Introduction: Intravital videomicroscopy of the sublingual microcirculation is used to monitor critically ill patients. Existing guidelines suggest handheld video recordings of ≥ 20 seconds from 5 areas. We tested if a fixated camera that allowed extension of the observation time could improve sensitivity in microcirculatory assessment. Methods: Anesthetized pigs (n=8), which were equally divided to a handheld group where microcirculation was assessed continuously in 1 min in 5 areas, and a group with a fixated camera where observation time was extended to 10 min in one area. The microcirculation was challenged by infusion of arginine vasopressin (AVP). Post ischemic acute heart failure (AHF) was induced by left coronary microembolization and the AVP infusion was repeated. Recordings were divided in 20 seconds sequences and Mean Flow Index (MFI) of small vessels were then scored and averaged for each measurement point. Results: When giving 0.003, 0,006 and 0,012 IU/kg/min of AVP, MFI in the fixated 10 min group was significantly more reduced (2,03±0,38, 0,98±0,18, 0,48±0,11) compared to both the first 20 seconds (2,77±0,04, 2,06±0,04, 1,74±0,06) and the total 1 min (2,63±0,09, 1,70±0,07, 1,33±0,16) in the handheld group. Following induction of acute heart failure, cardiac output dropped to half of the pre ischemic values. Interestingly, MFI was further decreased when giving 0,001 and 0,003 IU/kg/min of AVP in AHF (1,62±0,60 and 1,16±0,38) compared to pre-ischemia (2,86±0,09 and 2,03±0,38). Conclusion: A fixated camera with extended recording times reveals important microcirculatory changes in shock-states not detected by the guideline approach.