Distinct alterations in sublingual microcirculatory blood flow and hemoglobin oxygenation in on-pump and off-pump coronary artery bypass graft surgery.
OBJECTIVE
The authors hypothesized that cardiopulmonary bypass (CPB) (on-pump) is associated with more severe changes in the microcirculatory blood flow and tissue oxygenation as compared with off-pump coronary artery bypass surgery.


METHODS
An observational study.


METHODS
A university hospital and teaching hospital.


METHODS
Patients undergoing on-pump (n = 24) or off-pump (n = 24) cardiac surgery.


METHODS
Microcirculatory measurements were performed before CPB and 10 minutes after the switch to CPB or before and during cardiac luxation in off-pump patients.


RESULTS
Sublingual microcirculatory perfusion was investigated using side-stream dark field imaging, and sublingual microcirculatory oxygenation was measured using reflectance spectrophotometry. Conversion to CPB resulted in an increase in cardiac output from 4.0 ± 0.2 to 4.8 ± 0.3 L/min (p < 0.01) and a 40% reduction in arterial hemoglobin concentration. Cardiopulmonary bypass was associated with an increase in venular blood velocity from 349 ± 201 μm/s to 563 ± 227 μm/s (p < 0.05), a reduction in functional capillary density of 43%, and an increase in hemoglobin oxygenation of the red blood cells in the remaining filled capillaries from 47.2% ± 6.1% to 59.7% ± 5.2% (p < 0.001). The decrease in cardiac output during cardiac luxation from 4.5 ± 1.7 to 1.8 ± 0.8 L/min (p < 0.01) without hemoglobin changes was associated with a complete halt of capillary blood flow and a reduction in maximum capillary blood velocity from 895 ± 209 to 396 ± 178 μm/s (p < 0.01). The functional capillary density remained unchanged, whereas the hemoglobin oxygenation declined from 64.2% ± 9.1% to 48.6% ± 8.7% (p < 0.01).


CONCLUSIONS
On-pump and off-pump cardiac surgery are associated with distinct alterations in sublingual microcirculatory perfusion and hemoglobin oxygenation. Although on-pump surgery results in a fall out of capillaries resulting in decreased oxygen extraction, off-pump surgery results in a cessation of flow during luxation resulting in decreased convection of oxygen transport.
Department of Translational Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. b.atasever@vumc.nl
Bektaş
B
Atasever
Christa
C
Boer
Peter
P
Goedhart
Jules
J
Biervliet
Jan
J
Seyffert
Ron
R
Speekenbrink
Lothar
L
Schwarte
Bas
B
de Mol
Can
C
Ince
D000368:Aged; D002196:Capillaries / Q000502:physiology; D006348:Cardiac Surgical Procedures; D001026:Coronary Artery Bypass; D047549:Coronary Artery Bypass, Off-Pump; D048909:Diabetes Complications / Q000628:therapy; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D006973:Hypertension / Q000150:complications; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D009060:Mouth Floor / Q000098:blood supply*; D005996:Nitroglycerin; D010101:Oxygen Consumption / Q000502:physiology*; D012984:Software; D014665:Vasodilator Agents; D014699:Venules / Q000502:physiology
D006454:Hemoglobins; D014665:Vasodilator Agents; D005996:Nitroglycerin