OBJECTIVES: The purpose of this study was to investigate the effects of acute peritonitis on lymphatic drainage of the peritoneal cavity in conscious sheep. DESIGN: Peritonitis was induced with the addition of 1% casein or 1% albumin to the dialysis solution. Thirty sheep (5 groups of 6) were used in this study. One group received 50 mL/kg intraperitoneal infusions of Dianeal 4.25% (486 mOsm/L); a second group received 1% casein-Dianeal 4.25% (493 mOsm/L); a third group received 1% albumin-Dianeal 4.25% (487 mOsm/L). In the fourth and fifth groups (controls and casein-injected) lymph was collected from the caudal mediastinal lymph node and the thoracic duct, both of which are involved in the lymphatic drainage of the peritoneal cavity (peritonitis induced with casein). (125)I-human serum albumin (25 mu CI) was added to the dialysate as the lymph flow marker. Lymph drainage was estimated from (1) the appearance of the intraperitoneally administered tracer in the blood; (2) the disappearance of the tracer from the peritoneal cavity; and (3) the recovery of tracer in lymph. RESULTS: In noncannulated animals the cumulative volume removed by lymphatics over 6 hours (based on tracer recovery in blood) was 10.5 +/- 1.0 mL/kg in control animals versus 5.0 +/- 0.6 mL/kg and 8.6 +/- 1.2 mL/kg in casein and albumin-infused sheep, respectively. The suggestion of decreased lymph drainage in peritonitis was supported by the cannulation experiments. While the cumulative fluid removed from the peritoneal cavity over 6 hours in caudal lymph was unaffected by peritonitis (3.8 +/- 0.4 mL/kg in controls vs 3.6 +/- 0.5 mL/kg in casein-injected animals), peritonitis reduced flow into the thoracic duct from 3.0 +/- 0.3 to 1.1 +/- 0.3 mL/kg. The sum of the volume removed in lymph in the cannulated preparations was 6.8 +/- 0.4 mL/kg in controls versus 4.7 +/- 0.5 mL/kg in the peritonitis group. The total volume removed from the cavity (including an estimate of flow based on the residual recovery of tracer in blood) was reduced from 12.6 +/- 1.4 in controls to 7.8 +/- 0.6 mL/kg in the peritonitis sheep. In contrast, estimates of lymph drainage based on the disappearance of tracer from the peritoneal cavity suggested that lymph drainage increased (from 16.6 +/- 1.6 mL/kg in controls to 17.8 +/- 1.5 mL/kg and 25.5 +/- 1.7 mL/kg in the casein and albumin groups, respectively, in noncannulated animals and from 15.3 +/- 1.4 mL/kg in controls to 25.0 +/-1.7 mL/kg in the cannulated group). In both noncannulated and cannulated sheep the total recovery of tracer was less in the peritonitis groups. CONCLUSIONS: These studies demonstrated that lymph drainage of the peritoneal space was decreased in a casein peritonitis model. The decrease in lymph drainage is most obvious in the visceral pathway leading to the thoracic duct; however, diaphragmatic drainage into the right lymph duct may also be inhibited. The disappearance of tracer from the peritoneal cavity was elevated during peritonitis. Tracer disappearance has been used to estimate lymph drainage, but this approach suggested, incorrectly, that lymph flow had increased.

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