Abstract
BackgroundIn the present study we developed, evaluated in volunteers, and clinically validated an image acquisition stabilizer (IAS) for Sidestream Dark Field (SDF) imaging.MethodsThe IAS is a stainless steel sterilizable ring which fits around the SDF probe tip. The IAS creates adhesion to the imaged tissue by application of negative pressure. The effects of the IAS on the sublingual microcirculatory flow velocities, the force required to induce pressure artifacts (PA), the time to acquire a stable image, and the duration of stable imaging were assessed in healthy volunteers. To demonstrate the clinical applicability of the SDF setup in combination with the IAS, simultaneous bilateral sublingual imaging of the microcirculation were performed during a lung recruitment maneuver (LRM) in mechanically ventilated critically ill patients. One SDF device was operated handheld; the second was fitted with the IAS and held in position by a mechanic arm. Lateral drift, number of losses of image stability and duration of stable imaging of the two methods were compared.ResultsFive healthy volunteers were studied. The IAS did not affect microcirculatory flow velocities. A significantly greater force had to applied onto the tissue to induced PA with compared to without IAS (0.25 ± 0.15 N without vs. 0.62 ± 0.05 N with the IAS, p < 0.001). The IAS ensured an increased duration of a stable image sequence (8 ± 2 s without vs. 42 ± 8 s with the IAS, p < 0.001). The time required to obtain a stable image sequence was similar with and without the IAS. In eight mechanically ventilated patients undergoing a LRM the use of the IAS resulted in a significantly reduced image drifting and enabled the acquisition of significantly longer stable image sequences (24 ± 5 s without vs. 67 ± 14 s with the IAS, p = 0.006).ConclusionsThe present study has validated the use of an IAS for improvement of SDF imaging by demonstrating that the IAS did not affect microcirculatory perfusion in the microscopic field of view. The IAS improved both axial and lateral SDF image stability and thereby increased the critical force required to induce pressure artifacts. The IAS ensured a significantly increased duration of maintaining a stable image sequence.
Highlights
In the present study we developed, evaluated in volunteers, and clinically validated an image acquisition stabilizer (IAS) for Sidestream Dark Field (SDF) imaging
In the present study we developed, evaluated, and validated an IAS for the SDF device
The force applied by the SDF imaging probe onto the mucosal tissue required to induce pressure artifacts was significantly (p < 0.001) higher with the IAS (0.62 ± 0.05 N) compared to without the IAS (0.25 ± 0.15 N)
Summary
In the present study we developed, evaluated in volunteers, and clinically validated an image acquisition stabilizer (IAS) for Sidestream Dark Field (SDF) imaging. Orthogonal Polarization Spectral (OPS) imaging and its successor Sidestream Dark Field (SDF) imaging are optical techniques allowing microscopic assessment of microcirculatory density and perfusion in clinical settings [1,2]. These non-invasive intravital imaging modalities have been used in studies for monitoring the severity of shock and efficacy of resuscitation in various patient groups [3,4,5,6]. Pressure artifacts caused by the physical contact and pressure of the microscope probe to the mucosal tissue can alter mucosal capillary blood flow thereby limit the use of the captured images for determination of microcirculatory perfusion
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