Effect of sternotomy and extracorporeal circulation on pulmonary neutrophil kinetics in pigs

Pulmonary margination of neutrophils may contribute to lung damage after extracorporeal circulation for cardiac surgery. We evaluated single-pass pulmonary neutrophil kinetics using the multiple indicator-dilution technique in control pigs (n = 10), after sternotomy alone (sterno, n = 10) or after 30 min of observation following a period of 90 min extracorporeal circulation (n = 7). Blood neutrophils increased in the control and sterno groups (p < 0.05) but remained unchanged in the extracorporeal circulation group. The transfer coefficient for neutrophil margination from the circulating to the lung-marginated pool (k(c-m)) and pulmonary neutrophil clearance (Cl(c-m)) were similar between the three groups. There was an inverse correlation between k(c-m) and the degree of lung tissue perfusion evaluated from the tracer-accessible extravascular lung water (r = -0.54, p < 0.01). There was no arterio-venous gradient of neutrophils in any of the groups, suggesting a dynamic equilibrium of the margination/demargination processes. We conclude that extracorporeal circulation does not significantly modify single pass pulmonary neutrophil kinetics 30 min after reperfusion. The rate of neutrophil margination to the tracer-accessible lung tissue suggests that lung tissue de-recruitment is associated with increased neutrophil margination.