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Pulmonary abnormalities after cardiac surgery are better explained by atelectasis than by increased permeability oedema
Author(s) -
Verheij J.,
Van Lingen A.,
Raijmakers P. G. H. M.,
Spijkstra J.J.,
Girbes A. R. J.,
Jansen E. K.,
Van Den Berg F. G.,
Groeneveld A. B. J.
Publication year - 2005
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.2005.00831.x
Subject(s) - medicine , atelectasis , mechanical ventilation , cardiac surgery , anesthesia , pulmonary edema , cardiopulmonary bypass , pulmonary shunt , oncotic pressure , cardiac index , lung , cardiology , surgery , hemodynamics , cardiac output , albumin
Background: Cardiac surgery can be complicated by pulmonary abnormalities, but it is unclear how various manifestations interrelate. Methods: A prospective study in the intensive care unit was performed on 26 mechanically ventilated patients without cardiac failure within 3 h after elective cardiac surgery involving cardiopulmonary bypass. Oedema (extravascular lung water, EVLW) was measured by the thermal‐dye technique and permeability by a dual radionuclide technique, yielding a pulmonary leak index (PLI). Radiographic, mechanical and gas exchange features were used to calculate the lung injury score (LIS), ranging between 0 and 4. Evidence for left lower lobe atelectasis was obtained from plain radiographs. The plasma colloid osmotic pressure (COP) was measured by an oncometer. Results: The EVLW (normal, <7 ml/kg) was elevated in 36% of patients and the PLI (normal, <14.1 × 10 −3 /min) in 44%, but the variables did not interrelate directly. Patients with a supranormal EVLW had a lower COP than patients with normal EVLW. The duration of mechanical ventilation was prolonged in patients (20%) with EVLW > 10 ml/kg. There was no difference in EVLW and PLI in patients with LIS < 1 and LIS > 1 (31% of patients). In patients with radiographic evidence for atelectasis (46%), the positive end‐expiratory pressure and inspiratory O 2 fraction to maintain oxygenation were higher than in those without. Conclusions: After cardiac surgery, mild pulmonary oedema is relatively common, even in the absence of high filling pressures, and is mainly attributable to a low COP, irrespective of increased permeability in about one‐half of patients. It may prolong mechanical ventilation at EVLW > 10 ml/kg. However, pulmonary radiographic and ventilatory abnormalities may result, at least in part, from atelectasis rather than increased permeability oedema.