June 16, 2022
Handheld vital microscopy allows direct observation of red blood cells within the sublingual microcir- culation. Automated analysis allows quantifying microcircu- latory tissue perfusion variables – including tissue red blood cell perfusion (tRBCp), a functional variable integrating microcirculatory convection and diffusion capacities.
We aimed to describe baseline microcirculatory tissue perfusion in patients presenting for elective noncar- diac surgery and test that microcirculatory tissue perfusion is preserved during elective general anaesthesia for noncardiac surgery.
DESIGN Prospective observational study.
SETTING University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
120 elective noncardiac surgery patients (major abdominal, orthopaedic or trauma and minor urologic sur- gery) and 40 young healthy volunteers.
MAIN OUTCOME MEASURES
We measured sublingual microcirculation using incident dark field imaging with auto- mated analysis at baseline before induction of general anaes- thesia, under general anaesthesia before surgical incision and every 30 min during surgery. We used incident the dark field imaging technology with a validated automated analysis software.
A total of 3687 microcirculation video sequences were analysed. Microcirculatory tissue perfusion variables varied substantially between individuals – but ranges were similar between patients and volunteers. Under general anaesthesia before surgical incision, there were no important changes in tRBCp, functional capillary density and capillary haematocrit compared with preinduction baseline. However, total vessel density was higher and red blood cell velocity and the proportion of perfused vessels were lower under general anaesthesia. There were no important changes in any microcirculatory tissue perfusion variables during surgery.
In patients presenting for elective noncar- diac surgery, baseline microcirculatory tissue perfusion vari- ables vary substantially between individuals – but ranges are similar to those in young healthy volunteers. Microcirculatory tissue perfusion is preserved during general anaesthesia and noncardiac surgery – when macrocirculatory haemody- namics are maintained.