Chest wall strapping in a porcine model: A model for the physiology of the oversized lung allograft

Restrictive lung disease (RLD) is the leading indication for lung transplantation. Donor-to-recipient size matching is challenging in RLD, especially oversizing. Chest-Wall-Strapping (CWS) is a technique forcing the lung to operate at lower volumes. We developed a porcine model of CWS to investigate limits of oversizing. Farm-raised pigs were intubated and mechanically ventilated. Computer tomography (CT) volumetry demonstrated that Total Lung Volume (TLV) at 25 cm H₂O end-expiratory pressure was 1,204 ml at baseline. Application of increasing doses of CWS reduced TLV to 879 ml (CWS-cuff inflated to 35 mm Hg) and reduced TLV to 620 ml (CWS-cuff inflated to 50 mm Hg). At 50 mm Hg of CWS (50% TLV reduction) atelectasis of the lung bases was evident. Lung elastance was increased with CWS. CT lung-density at 35 mm Hg CWS (30% reduction in TLV) was normal for the inflation state of the lung. Physiological limits of oversizing should be considered for optimal lung function.