Effect of increased pump flow on hepatic blood flow and systemic inflammatory response following on-pump coronary artery bypass grafting.
Reduced organ perfusion during cardiopulmonary bypass (CPB) is responsible for morbidity associated with cardiac surgery. Non-pulsatile flow and hypothermia during CPB have been shown to cause reduced perfusion. During CPB, cardiac output is directly proportional to the pump flow rate. Therefore, we hypothesised that increasing pump flow during hypothermic CPB would improve organ perfusion and reduce the inflammatory response in the post-operative period.


METHODS
Ethics committee approval was obtained. Twelve consecutive patients with good or moderate left ventricular function undergoing elective or inpatient coronary artery bypass grafting were included in the study after obtaining informed consent. Patients were randomised to receive either normal flow or higher pump flow (20% more than the usual flow during hypothermia). Hepatic blood flow, cytokines such as interleukins 1β, 6, 8, 10 and 12, tumour necrosis factor-α and complements C3a, C4a and C5a were measured during the peri-operative period. Data were analysed using SPSS (ver.15). Categorical data were compared using the chi-square test and trends in cytokines were compared using a repeated measures ANOVA test.


RESULTS
Both the groups were similar in pre- and peri-operative variables. Hepatic blood flow almost doubled in the high-pump-flow group following an increase in the flow rate during hypothermia(p=0.026). The release of serum complement IL-6 and 8 appeared to be reduced in the high-flow group; however, the difference did not reach statistical significance.


CONCLUSIONS
Higher pump flows during hypothermic CPB increase hepatic blood flow. There was a trend towards attenuation of post-operative inflammatory response; however, larger studies will be needed to confirm these findings.
Adluri
Rajeshwara Krishna Prasad
RK
Department of Cardiac Surgery, Trent Cardiac Centre, Nottingham City Hospital, Nottingham, UK. arkrishnap@yahoo.com
Singh
Arvind V
AV
Skoyles
Julian
J
Hitch
Tony
T
Robins
Adrian
A
Baker
Mya
M
Mitchell
Ian M
IM
D003165:Complement System Proteins / Q000032:analysis; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000379:methods; D016207:Cytokines / Q000097:blood; D006353:Heart-Assist Devices / Q000009:adverse effects*; D007249:Inflammation / Q000209:etiology*; D008099:Liver / Q000098:blood supply*; D059035:Perioperative Period; D012039:Regional Blood Flow; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D016207:Cytokines; D014409:Tumor Necrosis Factor-alpha; D003165:Complement System Proteins