Water and protein movement in the sheep lung after septic shock: Effect of colloid versus crystalloid resuscitation

The pulmonary effects of colloid vs crystalloid solutions in resuscitation from septic shock remain controversial. Previous work by us showed increased albumin extravasation in the lung and increased mortality in baboons resuscitated with plasmanate (PL) compared to Ringer's lactate (RL). The present experiments were done using the Staub sheep model to provide correlation of pulmonary lymph flow and lymph protein concentration with hemodynamic and lung water changes. Seventeen sheep were studied; 5 were controls and 12 received 5 × 10⁸ organisms per kilogram live E. coli intravenously and were observed for a 2-hr shock period followed by a 2-hr resuscitation period. PL or RL was administered in sufficient volume to maintain left atrial pressure at 12 cm H₂O. Pulmonary, left atrial, systemic arterial, and venous pressures, extravascular lung water (EVLW), pulmonary lymph flow ( Q ̇_L), and lymph (L Alb) and plasma albumin (P Alb) concentrations were measured every 30 min during shock and resuscitation. Microvascular pressure (P_mv) was calculated. Q ̇_L and P_mv did not differ in the PL and RL groups. Q ̇_L was directly proportional to P_mv in all animals, indicating that resistance to lymph flow is constant and independent of P_mv or treatment regimen. P Alb, L Alb, L Alb flux, and EVLW were significantly different (P < 0.05) during the resuscitation period in the two groups and showed parallel changes. We conclude that EVLW following resuscitation from sepsis is increased with PL vs RL and that this results from increased plasma and lymph albumin concentrations and increased pulmonary interstitial albumin flux. No evidence of increased permeability to albumin was found during this acute experiment. Q ̇_L did not differ in the PL and RL groups and did not contribute to the increased edema in the PL group.