Sepsis disturbs alveolar perfusion distribution in rat lungs

Intra-abdominal sepsis causes pulmonary neutrophil accumulation and ARDS, but its effects on inter-alveolar perfusion distribution are unknown. To investigate this, we induced sepsis by instilling live bacteria (E.coli, B. fragilis) into the abdomens of rats. Twentyfour hours later we infused 4 μm diameter fluorescent latex particles (2x108) into the pulmonary circulation via a peripheral vein. We then removed and air-dried the lungs. We used dispersion index analysis (DI) to quantify latex particle distributions in confocal microscopic images of each lung (2x105 alveoli & 3x103 particles per image). The greater the value of logDI, the more the perfusion distribution is disordered. LogDI in septic lungs averaged 1.33±0.04 (n = 2). LogDI in control lungs averaged 0.53±0.04 (n=4) (P = 0.005). We conclude that intra-abdominal sepsis causes significant mal-distribution of inter-alveolar perfusion. Supported by VA Merit Review.