The FEA model demonstrates a 20-fold increase in pleural stress in the apex of chests with low thoracic index typical of spontaneous pneumothorax patients. Mild changes in thoracic index, as occurring in females or with aging, reduce pleural stress. Spontaneous pneumothorax occurring in young male adults may have a biomechanical cause.

The normal rib cage closely fits the ellipsoid FEA model. Lateral chest wall forces were significantly higher in the barrel-shaped chest. Rotational moments generated by forces acting on a six-sternal-wire closure at the suprasternal notch were sufficient to cause lateral distraction pivoting at the top of the manubrium. The six-sternal-wire closure may be successfully enhanced by the addition of one or two extra wires at the lower end of the sternotomy, depending on chest wall shape.

Acute kidney injury following cardiac surgery (AKICS) remains a frequent cause of major morbidity and mortality. The aim of this study was to examine the influence of timing of dialysis. A retrospective analysis of 3528 patients undergoing cardiac surgery between April 1995 and July 2006 was performed. In group 1 (April 1995-January 2000) intermittent haemodialysis was resorted to when other supportive measures failed. In group 2 (January 2000-July 2006) intermittent haemodialysis was commenced immediately when oliguria did not respond to fluid replacement or single-dose diuretics. In group 1, 49/1511 (3.2%) patients developed AKICS. Thirty-four patients did not receive dialysis and six patients died (18%). Of the remaining 15 patients who underwent dialysis, 13 died (87%). The overall mortality for group 1 AKICS patients was 19/49 (39%). In group 2, 87/2017 (4.3%) patients developed AKICS. Thirty-one patients did not require dialysis and none died. Of the 56 patients who were dialysed, 14 died (25%). During January 2005-July 2006, mortality following dialysis fell further to 17% (4/24). The overall mortality for group 2 patients developing AKICS was 14/87 (16%). Although the incidence of AKICS increased from 3.2% to 4.2%, earlier dialysis resulted in significantly improved survival (P=0.00001).

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