The pathogenesis of low pleural fluid glucose in acidotic malignant pleural effusions.
To clarify the pathogenesis of low glucose concentrations in acidotic pleural fluid of malignant effusion, simultaneous studies of 1) serial plasma-pleural fluid glucose, pH, PCO2, gentamicin, tobramycin and netilmicin in vivo, and 2) serial in vitro incubation of pleural fluid pH and PCO2 were conducted in 19 cases. In all effusion samples, the pleural fluid pH and PO2 levels were lower and the CO2 levels were higher than those of arterial blood, respectively. The pleural fluid aminoglycoside levels increased gradually, reaching the maximum values after about four to seven hours, thereafter, it gradually decreased. There were three types of serial pleural fluid-plasma glucose concentrations, of which types 2 and 3 showed either a delayed rise or no rise in pleural fluid glucose concentrations, respectively. Serial pleural fluid pH and PCO2 levels remained stable during the in vitro incubation study, especially during the first three hours. The pleural fluid kinetics of the three aminoglycosides followed a large reservoir model without any relationships to pleural fluid pH, PCO2, fluid-volume and no significant differences of the kinetics among the three aminoglycosides. This indicated that the diffusion block of the antibiotics did not depend on molecular weight nor pH, PCO2 dependent. Since the molecular weight of three aminoglycosides is greater than that of glucose, lactic acid, CO2 and O2, it may be concluded, therefore, that an over utilization of glucose and O2 with an over production of lactic acid and CO2 by the pleura, rather than glucose transport defect, results in a low glucose concentration in malignant effusions.
Limthongkul
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D000328:Adult; D000368:Aged; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000032:analysis; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010994:Pleura / Q000378:metabolism*; D010996:Pleural Effusion / Q000188:drug therapy / Q000378:metabolism*; D010997:Pleural Neoplasms / Q000378:metabolism*
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D005947:Glucose