EFFECT OF LUNG-INFLATION AND STERNOTOMY DIRECTION ON PLEURAL SPACE VIOLATION

Patients often are disconnected temporarily from the ventilator before sternotomy to avoid entering the pleural space with the sternal saw. Although this practice is widespread, it is based on questionable phys iologic principles. To evaluate the efficacy of this maneuver in reduc ing the incidence of pleural space violation with first-time sternotom y, 126 cardiac patients were randomized prospectively to either lungs inflated or deflated during sternotomy with the surgeon blinded to the particular assignment. The incidence of pleural space violation overa ll was 12%, occurring in 15% of patients with deflated lungs and in 9% of those with inflated lungs (p = 0.455 by chi(2) test). Examining th e effect of the direction of sternotomy on pleural space entry reveale d a 4% incidence with sternotomy starting at the xiphoid versus a 21% incidence with sternotomy starting at the sternal notch (p = 0.009 by chi(2) test). Preexisting hyperinflation of the lungs as evaluated by chest radiograms did not influence the incidence of pleural space viol ation. To reduce pleural space violation, sternotomy should be perform ed from the xiphoid to the sternal notch. More importantly, disconnect ing the patient from the ventilator does not reduce pleural space viol ation with sternotomy and its further use is not indicated. These find ings are discussed in the context of relevant heart-lung pathophysiolo gy.