Changes in lung water and capillary permeability following sepsis and fluid overload

Abstract

The presence or absence of permeability changes in the pulmonary parenchyma during sepsis is a controversial point in the literature. Clinical experience indicates an increase in pulmonary as well as systemic capillary permeability in septic patients. Eighteen dogs were studied. Ten received 4.8 × 10 9 organisms/kg of live Escherichia coli intravenously and were fluid overloaded in 5-cm H 2O increments during a 6-hr period to a left atrial pressure (LAP) of 35 cm H 2O; eight dogs were similarly volume overloaded without a septic insult. Cardiac output, extravascular lung water (EVLW), blood pressure, pulmonary artery pressure, LAP, and central venous pressure were measured in both groups at each LAP elevation. Results are: Group EVLW (ml/kg) Nonseptic + fluid ( N = 8) 6.3 6.8 8.6 11.7 - 11.2 Septic + fluid ( N = 10) 7.4 7.9 9.6 15.0 19.1 - LAP (cm H 2O) 2–4 15 20 25 30 35 As seen above the septic animals had a greater increase in EVLW than the volume-overloaded dogs, reaching statistical significance at a LAP of 35 cm H 2O ( P < 0.001). EVLW showed a strong positive correlation, as it has in the past, with increasing LAP. We conclude that there is a permeability change which occurs in the lung following sepsis but this does not occur immediately and requires increased pulmonary capillary pressure and/or time to become manifest; this finding implies that the permeability lesion is not a direct result of bacteremia or endotoxemia but results from an intermediary mechanism.