Mechanisms of pulmonary dysfunction after on-pump and off-pump cardiac surgery: a prospective cohort study.
BACKGROUND
Pulmonary dysfunction following cardiac surgery is believed to be caused, at least in part, by a lung vascular injury and/or atelectasis following cardiopulmonary bypass (CPB) perfusion and collapse of non-ventilated lungs.


METHODS
To test this hypothesis, we studied the postoperative pulmonary leak index (PLI) for 67Ga-transferrin and (transpulmonary) extravascular lung water (EVLW) in consecutive patients undergoing on-pump (n = 31) and off-pump (n = 8) cardiac surgery. We also studied transfusion history, radiographs, ventilatory and gas exchange variables.


RESULTS
The postoperative PLI and EVLW were elevated above normal in 42 and 29% after on-pump surgery and 63 and 37% after off-pump surgery, respectively (ns). Transfusion of red blood cell (RBC) concentrates, PLI, EVLW, occurrence of atelectasis, ventilatory variables and duration of mechanical ventilation did not differ between groups, whereas patients with atelectasis had higher venous admixture and airway pressures than patients without atelectasis (P = 0.037 and 0.049). The PLI related to number of RBC concentrates infused (P = 0.025).


CONCLUSIONS
The lung vascular injury in about half of patients after cardiac surgery is not caused by CPB perfusion but by trauma necessitating RBC transfusion, so that off-pump surgery may not afford a benefit in this respect. However, atelectasis rather than lung vascular injury is a major determinant of postoperative pulmonary dysfunction, irrespective of CPB perfusion.
Groeneveld
A B Johan
AB
Department of Intensive Care, VU University Medical Center, Amsterdam, The Netherlands. johan.groeneveld@vumc.nl
Jansen
Evert K
EK
Verheij
Joanne
J
D055371:Acute Lung Injury / Q000209:etiology*; D000328:Adult; D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000379:methods; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D015633:Extravascular Lung Water; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D001261:Pulmonary Atelectasis / Q000209:etiology*; D012123:Pulmonary Ventilation; D012307:Risk Factors