Patients with premature ventricular contractions are also frequently hypoxemic (HO) and/or hypercapnic (HC). The aims of the present study were to document the effect of HO and/or HC on the kinetics of lidocaine, a first choice drug for the i.v. treatment of premature ventricular contractions, and on indocyanine green (ICG), another flow-dependent drug. For this purpose, five groups of rabbits were used: a control group received 2.5 mg/kg i.v. of ICG followed, 30 min later, by 7.5 mg/kg of lidocaine as a bolus. Four other groups received lidocaine as an infusion (261 micrograms/min/kg) for 255 min and ICG (249 micrograms/min/kg) for 8 min, the latter beginning 180 min after the start of the lidocaine infusion. The controls and one test group receiving the lidocaine infusion were breathing air (PaO2 = 89 +/- 2 (S.E.M.) and PaCO2 = 20 +/- 1 mm Hg); the second test group had HO (PaO2 = 51 +/- 1 mm Hg), a third group HC (PaO2 = 68 +/- 1 mm Hg) and the fourth HO combined with HC (HOHC) (PaO2 = 53 +/- 1 and PaCO2 = 61 +/- 2 mm Hg). Multiple blood samples were drawn. Lidocaine and its metabolites and ICG were assayed by high-performance liquid chromatography. Lidocaine volume of distribution was not affected by HO and/or HC. Compared to control values, the clearance of infused lidocaine (CIL) tended to decrease from 65 +/- 2 to 53 +/- 3 ml/min/kg. In animals with HO, HC and HOHC, CIL was 49 +/- 6, 45 +/- 5 and 46 +/- 3 ml/min/kg, respectively, these values not being significantly different from CIL.(ABSTRACT TRUNCATED AT 250 WORDS)