Regional muscle tissue saturation is an indicator of global inadequate circulation during cardiopulmonary bypass: a randomized porcine study using muscle, intestinal and brain tissue metabolomics.
BACKGROUND
Muscle tissue saturation (StO2) measured with near-infrared spectroscopy has generally been considered a measurement of the tissue microcirculatory condition. However, we hypothesized that StO2could be more regarded as a fast and reliable measure of global than of regional circulatory adequacy and tested this with muscle, intestinal and brain metabolomics at normal and two levels of low cardiopulmonary bypass blood flow rates in a porcine model.


METHODS
Twelve 80 kg pigs were connected to normothermic cardiopulmonary bypass with a blood flow of 60 mL/kg/min for one hour, reduced randomly to 47.5 mL/kg/min (Group I) or 35 mL/kg/min (Group II) for one hour followed by one hour of 60 mL/kg/min in both groups. Regional StO2was measured continuously above the musculus gracilis (non-cannulated leg). Metabolomics were obtained by brain tissue oxygen monitoring system (Licox) measurements of the brain and microdialysis perfusate from the muscle, intestinal mucosa and brain. A non-parametric statistical method was used.


RESULTS
The systemic parameters showed profound systemic ischaemia during low CPB blood flow. StO2did not change markedly in Group I, but in Group II, StO2decreased immediately when blood flow was reduced and, furthermore, was not restored despite blood flow being normalized. Changes in the metabolomics from the muscle, colon and brain followed the changes in StO2.


CONCLUSIONS
We found, in this experimental cardiopulmonary bypass model, that StO2reacted rapidly when the systemic circulation became inadequate and, furthermore, reliably indicate insufficient global tissue perfusion even when the systemic circulation was restored after a period of systemic hypoperfusion.
1 Department of Anaesthesiology and Intensive Care Medicine, Aalborg University Hospital, Aalborg, Denmark.|2 Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
Sisse Anette
SA
Thomassen
2 Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.|3 Department of Cardiothoracic Surgery, Aalborg University Hospital, Aalborg, Denmark.
Benedict
B
Kjærgaard
2 Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.|4 Department of Neurosurgery, Aalborg University Hospital, Aalborg, Denmark.
Preben
P
Sørensen
2 Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.|3 Department of Cardiothoracic Surgery, Aalborg University Hospital, Aalborg, Denmark.
Jan Jesper
JJ
Andreasen
5 Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
Anders
A
Larsson
1 Department of Anaesthesiology and Intensive Care Medicine, Aalborg University Hospital, Aalborg, Denmark.|2 Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
Bodil Steen
BS
Rasmussen
D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000378:metabolism; D002315:Cardiopulmonary Bypass; D002560:Cerebrovascular Circulation; D005260:Female; D006439:Hemodynamics; D007413:Intestinal Mucosa / Q000098:blood supply* / Q000378:metabolism; D055432:Metabolomics / Q000379:methods; D008833:Microcirculation; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism; D010100:Oxygen / Q000097:blood* / Q000378:metabolism; D010101:Oxygen Consumption; D011897:Random Allocation; D012039:Regional Blood Flow; D019265:Spectroscopy, Near-Infrared; D013552:Swine
D010100:Oxygen
Licox; animal study; blood flow; cardiopulmonary bypass; experimental pig model; metabolomics; microdialysis; near-infrared spectroscopy; oxygen demand; regional metabolism