THE EFFECT OF CARDIOPULMONARY BYPASS ON INTESTINAL AND PULMONARY ENDOTHELIAL PERMEABILITY

Study objective: To quantify simultaneously the pulmonary and gastroin testinal (GI) damage that occurs during uncomplicated surgery requirin g cardiopulmonary bypass (CPB), and to examine the relationships betwe en markers of such damage. Design: Prospective, open. Setting: Adult I CU of a national referral hospital. Patients: Twenty patients undergoi ng elective CPB surgery. Measurements and results: Pulmonary vascular injury was assessed using the protein accumulation index (PAI), a doub le isotope technique specific for high permeability pulmonary edema. T he relationships of the PAI with percent neutrophils in bronchoalveola r lavage (BAL), serum, and BAL myeloperoxidase (MPO), and bypass time were examined. Splanchnic vascular injury was assessed using tonometry to measure intramucosal pH (pHi) and the ratio of absorbed lactulose to L-rhamnose (L/R ratio) to determine gut mucosal permeability. Posit ive correlations were observed between bypass time and PAI (r=0.64, p< 0.01), percent neutrophils in the postoperative BAL and PAI (r=0.51, p <0.05), and postoperative serum MPO and PAI (r=0.77, p<0.001). The L/R ratio rose significantly following CPB from 0.04 +/- 0.01 in controls to 0.48 +/- 0.05 (p<0.0001). The L/R ratio in patients who developed a low pHi was 0.59 +/- 0.06 compared with 0.32 +/- 0.07 in those whose pHi remained normal (p<0.05). No significant correlation between bypa ss time and pHi (r=-0.3, p=0.33), bypass time and L/R ratio (r=0.27, p =0.26), PAI and L/R ratio (r=0.2, p=0.42), PAI and pHi (r=-0.34, p=0.1 6), postoperative serum MPO and UR ratio (r=0.03, p=0.90), or postoper ative serum MPO and pHi (r=-0.10, p=0.67) could be demonstrated. Concl usions: Pulmonary and GI injury are detectable following uncomplicated CPB. The absence of any relationship between the respective markers o f dysfunction suggests that differing pathologic processes are respons ible.