Importance of Liver Interstitial Pressure on Sodium Retention

Abstract

Experiments were performed on 23 dogs to assess the effect of splanchnic pooling on renal hemodynamics and Na retention. When the thoracic duct pressure was raised to 40 cm H₂O (HTDP), liver interstitial pressure rose from 9.0 ± 0.4 to 19.8 ± 1.1 cm H₂O. Simultaneously, glomerular filtration rate (GFR) and renal plasma flow fell in the left kidney from 16.3 ± 1.7 to 9.6 ± 1.3 and from 73.7 ± 12.2 to 44.3 ± 9.8 ml · min^-1, respectively (p < 0.01). U_Na · V fell to 59 ± 9% of control value (p < 0.01). Plasma antidiuretic hormone (ADH) rose from 29.5 ± 7.7 to 46.9 ± 9.2 pg·ml^-1 (p < 0.05). When a portocaval shunt (PCS) was opened in 10 dogs during HTDP after the first set of experimental measurements, splanchnic pressure fell from 17.2 ± 1.1 to 11.5 ± 1.2 cm H₂O, attended by a return towards control of GFR. ADH fell significantly to 16.5 ± 8.1 during PCS, and to 9.7 ± 1.5 pg · ml^-1 during a last, postexperimental control period. Instead, U_Na V remained unchanged at the low levels measured during HTDP alone. When the HTDP was released in the 17 dogs without, and the 10 dogs with PCS, all variables became indistinguishable from control, except for U_Na V, which remained reduced, even in 4 aldosterone-escaped animals. No significant change in any of these variables occurred in 6 sham-operated control animals. These data demonstrate that it is possible to increase interstitial liver pressure through the lymph duct. Renal hemodynamics is impaired and causes Na retention because of the activation of mechanisms sensitive to the fall in ‘effective’ central volume. Na retention outlives the hemodynamic effects, which are quickly reversible, suggesting that it may be either independent of the fall in GFR or maintained by mechanisms independent of hemodynamics.

Positive pressure ventilation: what is the real cost?

“…81 High thoracic duct pressure increases interstitial fluid in both liver and kidneys and has measurable effects on renal function. 110 This may provide linkage to the increasing evidence that excess fluid itself may delay recovery in areas as diverse as lower gastrointestinal surgery, free flap surgery, and ventilation of acute lung injury, although this is contentious. 22 56 62 63 109 145 The evidence for the effects of venous and lymphatic congestion impairing organ function is as yet rudimentary, but the physics is hard to dismiss.…”