Haemodynamic effects of -75 mmHg negative pressure therapy in a porcine sternotomy wound model

Previous research has shown -125 mmHg to be the optimal negative pressure for creating an environment that promotes wound healing, and this has therefore been adopted as a standard pressure for patients with deep sternal wound infection. However, it has not yet been clearly shown that -125 mmHg is the optimal pressure from a haemodynamic point of view. Furthermore, there have been reports of cardiac rupture during -125 mmHg negative pressure therapy. We therefore studied the effects of a lower pressure: -75 mmHg. Twelve pigs were used. After median sternotomy, sealed negative pressure therapy of -75 mmHg was applied. Baseline measurements were made and continuous recording of the cardiac output, end-tidal CO(2) production, mean arterial pressure, mean pulmonary pressure (pulmonary artery pressure), systemic vascular resistance, pulmonary vascular resistance, left atrial pressure and central venous pressure was started. Six pigs served as controls. No statistically significant difference was observed in any of the haemodynamic parameters studied, compared with the controls. The present study shows that, with a suitable foam application technique, -75 mmHg can be applied without compromising the central haemodynamics.