An evaluation of the pericardial sac as a safety factor during tamponade

Studies were conducted in vitro to determine the permeability characteristics of the rabbit and dog pericardium. The hydraulic conductance (Lp), which was significantly higher than other tissue, was 1.6 +/- 0.19 X 10(-4) and 1.78 +/- 0.18 X 10(-4) g-cm-2-min-1-cm H2O-1 (mean +/- SEM), respectively, for the rabbit and dog pericardium. For various solutes, the permeability coefficient (P) of the pericardium for the rabbit was: 1.40 +/- 0.10 X 10(-4) cm-s-1 for water, 0.50 +/- 0.03 X 10(-4) cm-s-1 for glucose, and 0.73 +/- 0.005 X 10(-4) cm-s-1 for albumin. The reflection coefficient, sigma, for various solutes was: glucose 8.89 +/- 0.86 X 10(-4), sucrose 15.7 +/- 1.5 X 10(-4), dextran (molecular weight 40 000) 0.39 +/- 0.03, albumin 0.42 +/- 0.05, and for haemoglobin 0.58 +/- 0.06. These results, which indicate that the pericardium offers little resistance to the bulk transfer of liquids and to the passage of large molecules, are discussed as possible safety factors during pericardial effusion.