Document resource
Background and Importance Nebulised antibiotics in respiratory infections increase lung exposure while minimising systemic effects.Aim and Objectives Evaluate systemic exposure after nebulised vancomycin and tobramycin in critically ill patients.Material and Methods Observational study in adults treated with nebulised vancomycin and tobramycin (March 2022–March 2025). Biodemographic, clinical, and laboratory data were collected, including trough plasma concentrations of vancomycin (Cp_vanco) and tobramycin (Cp_tobra). Continuous variables were expressed as mean±SD or median (interquartile range) and categorical as counts (%). Concentrations were compared with t-test or Mann–Whitney U, and proportions with Chi-square or Fisher’s exact test.Results We obtained 24 Cp_vanco in 15 patients, (60% male, mean age 54,2±17,1 years). Vancomycin (125 mg/12 hours) showed minimal systemic absorption (Cp_vanco > 0.1µg/mL) in 20 patients (80%), measured after 7 (4–10) days, with mean 0,9±0,7 µg/mL. Nineteen patients (79%) required mechanical ventilation (MV) and five (21%) MV+extracorporeal membrane oxygenation (ECMO), with no significant difference (mean 1,1 vs 0,9 µg/mL; p=0,57). Patients with glomerular filtration rate (GFR) < 60 mL/min (25%) had higher exposure (1,7 vs 0,9 µg/mL; p=0,008).For tobramycin, 36 Cp_tobra were obtained from 29 patients (72% male, mean age 56,2±20,1 years). Tobramycin (300 mg/12 h) showed systemic absorption (Cp_tobra > 0,1µg/mL) in 31 (86%), 17 (55%) were therapeutic (Ctrough > 0,5 µg/mL). Mean Cp_tobra, measured 6 (3-15) days after initiation, was 0,5 (0,2-1,5) µg/mL. Respiratory support was MV in 24 (77%) and high-flow oxygen therapy (HFOT) in 7 (23%). Mean Cp_tobra was higher in MV (0,7 vs 0,2 µg/mL; p=0,03), with a greater proportion of seric concentrations > 0,5 µg/mL in VM (67% vs 14%; p=0,03). No differences were found by renal function, with median Cp_tobra of 0,4 µg/mL in patients with GFR > 60 mL/min and 0,6 µg/mL in those with GFR < 60 mL/min (p = 0,23).Conclusion and Relevance Systemic exposure after nebulised vancomycin is minimal, not reaching therapeutic plasma levels (Cp_vanco>5 µg/mL), although renal impairment may contribute to higher exposure.Nebulised tobramycin achieves trough concentrations comparable to those expected with intravenous multiple-dose regimens, particularly in mechanically ventilated patients (greater proportion of Cp_tobra>0.5 µg/mL).Further studies are needed to assess the impact of this exposure on resistance development.Conflict of Interest No conflict of interest