The Annals of Thoracic Surgery, Vol 42, 406-411, Copyright © 1986 by The Society of Thoracic Surgeons
Changes in intrathoracic pressures induced by positive end-expiratory pressure ventilation after cardiac surgical procedures
F Bonnet, M Fischler, CL Dubois, D Brodaty, F Pluskwa, D Guilmet and G Vourc'h
The consequences of controlled ventilation with positive end-expiratory
pressure (PEEP) were studied, after cardiac surgical procedures, in two
groups of patients supposed to have different lung and chest wall
mechanical properties. The first group included 6 patients who had
undergone coronary artery graft surgical procedures (CGS). The second group
included 5 patients who had undergone a mitral valve replacement (MVR).
Postoperatively, static lung and chest wall compliance was measured by
stepwise inflation and deflation of the thorax. Esophageal, pericardial,
and pleural pressures were then measured, and cardiac output was determined
while PEEP was increased from 0 to 20 cm H2O. Lung and chest wall
compliance values sharply decreased in MVR patients. This accounts for the
lower values for pleural and pericardial pressures in this group than in
the CGS patient group, but the transmission of airway pressure was
identical in the two groups when PEEP was increased. The decrease in
cardiac output induced by PEEP was similar in the two groups. The results
suggest that the opposing influences of lung and chest wall compliance on
airway pressure transmission could at least partly explain the hemodynamic
effects of PEEP in patients in whom the mechanical properties of the lung
and thorax are impaired. PEEP ventilation should be used cautiously in
patients suspected of having thoracic rigidity.
