Objective: Cardiac surgery is associated with systemic inflammation and respiratory dysfunction. Cardiopulmonary bypass (CPB) has been implicated as a possible explanation. This study investigates the effects on systemic inflammatory response and lung function in patients undergoing CABG on- and off-CPB.
Methods: Eighty patients undergoing CABG were randomized into two groups: A) On-CPB and B) Off-CPB. Blood samples were taken pre-, intra- and post-operatively. Neutrophil expression of CD11b and plasma levels of interleukin-6 (IL-6), interleukin-10 (IL-10), myeloperoxidase (MPO) and lactoferrin (LTF) were measured. Pulmonary function tests including spirometry and diffusion studies were performed pre-operatively and on the fifth post-operative day. Arterial blood gases on 100% oxygen were taken pre-sternotomy (TP1), fifteen minutes post sternal closure (TP2) and three hours post surgery (TP3).
Results: The two groups were well matched demographically. The mean number of grafts were 3.8±0.9 and 4.1±0.8 in A and B respectively.
The table reveals all inflammatory markers were increased significantly in group A, *=p<0.05.
The transfer factor of carbon monoxide (TLCO) was significantly reduced postoperatively in group A but not B (7.9±2.5 falling to 5.1±1.6 mmol/min/kPa, p<0.05 and 6.9±1.5 falling to 5.7±2.6mmol/min/kPa, p>0.05, in A and B respectively). There was a significant difference between the groups. Spirometry revealed a significant reduction in FEV1 and FVC post-operatively in both groups with no difference between groups. The partial pressure of oxygen decreased significantly in both groups from TP1 to TP2 with no difference between groups (59.5±11.5 and 55.5±12.2 kPa falling to 39.5±16.3 and 39.7±13.1 kPa in A and B respectively, p<0.001).
Conclusions: On-pump CABG is associated with a significantly increased acute phase response and neutrophil activation compared to off-pump.
Gas exchange at the alveolar-capillary membrane, as measured by the TLCO is reduced significantly less in the off-pump group postoperatively and maybe representative of the significantly reduced inflammatory response in this group.
In our study off-pump patients had a significantly reduced systemic inflammatory response and significantly better lung function following surgery compared to their on-pump counterparts.