EFFECT OF LOW-DOSE ENDOTOXIN ON PULMONARY VASCULAR-PERMEABILITY FOLLOWING ACUTE HEMORRHAGIC-SHOCK

The purpose of the current study was to determine the effect of low-do se Escherichia coli lipopolysaccharide (LPS) on pulmonary vascular per meability when administered after hemorrhagic shock (40% of baseline c ardiac out-put) followed by resuscitation. Animals were monitored for 3-4 h after LPS infusion. Thirty minutes prior to termination of the e xperiment, 3 mCi of I-125-human serum albumin was injected intravenous ly to calculate a permeability index from the left lung lavage and pla sma I-125 ratios. The two control groups were (1) shock only (no LPS, n = 4), and (2) LPS only (no shock, n = 8). The permeability index for the shock-only group was 0.0015 +/- 0.0007 (mean +/- SE) and that for the LPS-only group was 0.0035 +/- 0.0014. The permeability index for the experimental group (shock followed by LPS, n = 10) was 0.0071 +/- 0.0030 (p > 0.05). Similarly, there was no difference in the wet-to-dr y ratios between the three groups. The shock + LPS group required more intravenous fluids to maintain mean arterial blood pressure at contro l values than the LPS-only group (p < 0.003). We conclude that hemorrh agic shock and resuscitation do not lead to an acute increased permeab ility of the lung when it is subsequently challenged by a low dose of bacterial LPS.