Distinct Alterations in Sublingual Microcirculatory Blood Flow and Hemoglobin Oxygenation in On-Pump and Off-Pump Coronary Artery Bypass Graft Surgery

• Published in: Journal of cardiothoracic and vascular anesthesia Vol. 25; no. 5; pp. 784 - 790
• Main Authors: Atasever, Bektaş, MD, Boer, Christa, PhD, Goedhart, Peter, BSc, Biervliet, Jules, MD, PhD, Seyffert, Jan, MD, PhD, Speekenbrink, Ron, MD, PhD, Schwarte, Lothar, MD, de Mol, Bas, MD, PhD, Ince, Can, PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2011
• Subjects: Aged; Anesthesia & Perioperative Care; Capillaries - physiology; Cardiac Surgical Procedures; cardiopulmonary bypass; Coronary Artery Bypass; Coronary Artery Bypass, Off-Pump; Critical Care; Diabetes Complications - therapy; Female; Hemodynamics - physiology; Hemoglobins - metabolism; Humans; Hypertension - complications; intravital microscopy; Male; Microcirculation - physiology; Middle Aged; Mouth Floor - blood supply; Nitroglycerin; off-pump surgery; Oxygen Consumption - physiology; reflectance spectrophotometry; Software; sublingual microcirculation; Vasodilator Agents; Venules - physiology; cardiopulmonary bypass; intravital microscopy; reflectance spectrophotometry; sublingual microcirculation; off-pump surgery
• ISSN: 1053-0770; 1532-8422
• DOI: 10.1053/j.jvca.2010.09.002

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. Design An observational study. Setting A university hospital and teaching hospital. Participants Patients undergoing on-pump (n = 24) or off-pump (n = 24) cardiac surgery. Interventions Microcirculatory measurements were performed before CPB and 10 minutes after the switch to CPB or before and during cardiac luxation in off-pump patients. Measurements and Main 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.