Pulmonary exchange of solutes during experimental lung lavage in pigs

Unilateral continuous lung lavage in a nonregenerating system (3,000 ml isotonic cristalloid) was done in 12 pigs for 270 min. The concentration of substances in serum and fluid was measured. Half-time (t1/2) of exchange and permeability constants (P) were determined. In the fluid Na+ decreased significantly (t1/2 = 107 min, P = 7.8 x 10(-7]. Urea increased significantly, reaching serum level after 270 min (t1/2 = 109.1 min, P = 6.18 x 10(-6]. Ca2+ (t1/2 = 36.7 min, P = 4.1 x 10(-7] PO4 = (t1/2 = 173.3 min, P = 1.1 x 10(-7], and creatinine (t1/2 = 55.2 min, P = 6.2 x 10(-7] also increased markedly but did not reach serum level. The adjustment to serum concentration may be prevented by interaction between diffusion, active transport or Donnan's equilibria. K+ increased almost linearly, documented by the long half-time (t1/2 = 7,835.2 min, P = 7.7 x 10(-7] and did not reach serum level. The calculated limit value was higher than the serum level. Active transport systems or influx of K+ from cellular compartments rather than from the serum might be involved in its linear kinetics. Total protein (t1/2 = 61.5 min, P = 2.06 x 10(-9] and albumin (t1/2 = 58.8 min, P = 1.7 x 10(-9] increased initially but levelled far below the serum value. The low P indicates a lack of significant permeation. Initial increase may be due to washout of the epithelial lining fluid compartment. There was minimal transfer of lavage fluid into the organism (10-20 ml/30 min). Serum concentrations were not affected by the lavage.