Plasma lidocaine levels and PaO2 with endobronchial administration: Dilution with normal saline or distilled water?

To determine whether water or 0.9% saline should be used as diluent for endobronchial drug administration.Twelve adult patients.Patients were endobronchially administered 2 mg/kg lidocaine as marker substance in either 10 mL 0.9% saline or 10 mL distilled water during general anesthesia.The differences in mean lidocaine plasma levels at five minutes (water vs saline, 2.35 vs 1.59 micrograms/mL) and ten minutes (water vs saline: 2.67 vs 1.88 micrograms/mL) were significant (P less than .05). With the initial mean PaO2 being almost (157 mm Hg; F1O2, 0.3) in the two groups, there was a mean drop of about 60 mm Hg in the saline-diluent group, but only about 40 mm Hg in the water-diluent group one minute after administration (P less than .05).The use of water resulted in better absorption of lidocaine and less impairment of the PaO2.